High performance nanocomposites

HIGH PERFORMANCE NANOCOMPOSITES

STATEMENT OF U.S. GOVERNMENT INTEREST

0003Funding for the present invention was provided in part by the Government of the United States by virtue of contract No. F33615-98-C-5029 and F33615-97-C-5098 from the U.S. Air Force. Thus, the Government of the United States has certain rights in and to the invention claimed herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

0005The present application claims the benefit of U.S.S.N. 60/152,515 entitled "High-Temperature Use Nanocomposites" filed on September 2, 1999, which application includes the disclosure of U.S.S.N. 09/090,864 entitled "High- Temperature Polymer/Inorganic Nanocomposites filed on June 5, 1998. The 09/090,864 application claims the benefit of U.S.S.N. 60/048,921 filed on June 6, 1997. The present application claims further benefit from U.S.S.N 60/139,481 entitled "Nanomaterials For Barrier Applications" filed on June 17, 1999 and U.S.S.N 60/126,048 entitled "Polymer Alloy Nanocomposites" filed on March 23, 1999. The disclosures of the 60/152,515, 09/090,864, 60/048,921, 60/139,481, and 60/126,048 applications are each hereby incoφorated by reference. The present application claims priority to the U.S.S.N. 60/048,921 application filed on June 6, 1997.

00061. Field of the Invention

0007The present invention features novel compositions that include at least one type of layered silicate. In one aspect, the invention features silicate compositions that include at least one type of layered silicate and at least one type of organophilic agent associated with the silicate. Also provided are nanocomposites that include the silicate composition and at least one suitable polymer material. The invention also features methods for making and using the silicate compositions. The present invention has a wide spectrum of useful applications including providing manufactured articles with exceptional performance characteristics. 2. Background A nanocomposite can be defined as an interacting mixture of two phases, one of which is in the nanometer size range in at least one dimension. The precise length scale of interest in any given case is one that creates unique material properties due to the nanoscale dimensions. Nanocomposite materials offer a wealth of unique properties and technological opportunities. Hence significant research effort has been devoted to exploring their potential for a wide variety of electrical, mechanical, optical, magnetic and other applications.

0008Polymer/inorganic nanocomposites have attracted much attention as the properties of polymers are further enhanced beyond what is achievable from more conventional particulate-filled or micro-composites. Specifically, layered mica-type- silicates have been widely used as inorganic reinforcements for polymer matrices to create polymer nanocomposites with nanoscale dispersion of the inorganic phase within the polymer matrix. Layered silicate-polymer nanocomposites having (i) polymer chains intercalated between the silicate layers or (ii) individual silicate layers delaminated and dispersed in a continuous polymer matrix, have been fabricated.

0009Surface modification in the existing nanocomposites is often achieved by using an organic surfactant such as alkyl ammonium. The organic cation exchange at the oxide surface provides favorable sites for interaction between the organic and inorganic funtionalities. That approach has been exploited and has been shown to offer significant performance advantages for a variety of commodity polymers. However, the thermal instability of the surfactants used has hindered that technology from realizing its full potential.

0010However, there has been recognition that prior silicate compositions and particularly nanocomposites have shortcomings. For example, it is increasingly apparent that many prior nanocomposites do not have the performance characteristics needed for optimal use. In particular, widespread nanocomposite use has been limited by unacceptable thermal stability, mechanical strength, interfacial design, heat distortion temperature, and polymer compatibility. An especially significant limitation of prior silicate compositions is unacceptable use-temperature. For example, there has been understanding that use of the prior nanocomposites has been limited to commodity polymers that have been reported to have long-term use temperatures below about 150°C. Similarly, optimal use of these silicate compositions has been restricted to below that temperature.

0011It would be desirable to have novel silicate compositions with improved performance characteristics and particularly better long-term use above about 150°C. It would also be especially desirable to use the silicate compositions to enhance use of a wide variety of manufactured articles including those relating to the automotive, aerospace, electronic, pharmaceutical, apparel, food and beverage packaging industries.

0012SUMMARY OF THE INVENTION The invention features compositions that include at least one type of inorganic layered silicate and at least one type of organophilic agent. In one aspect, the invention provides silicate compositions that include the inorganic layered silicate associated with the organophilic agent to achieve at least one desired characteristic. In another aspect, the invention provides nanocomposites that include at least one of the silicate compositions and at least one suitable polymer material. Also provided are methods for making and using the silicate compositions. The invention has many highly useful applications including providing manufactured articles with exceptional barrier properties.

0013We have discovered silicate compositions that feature a wide spectrum of important uses and advantages. In general, the silicate compositions represent a new generation of layered silicate compounds that provide highly desirable performance characteristics. Particular silicate compositions include at least one inorganic layered silicate associated with at least one organophilic agent to achieve the characteristics. More particular silicate compositions surprisingly provide for long-term use above about 150°C and are compatible with a wide range of polymer materials. Accordingly, the compositions and methods of this invention embody a significant advance in the design of stable silicate compositions for long-term or short-term use at high temperature.

0014By the term "polymer material" or related term is meant a polymer or polymer-like material that is useful at a high temperature e.g., above about 150°C. Suitable polymer materials for use in this invention include commodity polymers, graft polymers, resins, copolymers, block polymers; as well as blends or alloys thereof. Additionally, suitable polymer materials are those that can be adapted to provide high temperature use in excess of about 200°C, preferably between from about 200°C to 450°C, with between from about 250°C to about 400°C being preferred for many applications. In embodiments in which the term "polymer material" is used to describe particular components of a nanocomposite with favorable barrier characteristics, the polymer material may also be useful at temperatures below about 150°C.

0015Additionally preferred polymer materials for use in this invention are compatible with a wide variety of silicon-based layered materials and especially clay minerals such as those described below. Also preferred are polymer materials that provide good dispersion with most clay minerals while minimizing undesired plasticization.

0016It has also been found that many silicate compositions of this invention can be made by methods that generally enhance thermally stable surface chemistries. That is, we have learned that by associating the inorganic layered silicate with the organophilic agent, it is possible to make silicate compositions with suφrising and highly desirable performance characteristics. Without wishing to be bound to theory, it is believed that the association facilitates use at high temperature. Preferred association facilitates favorable interlayer spacing within the silicate and provides for good compatibility between the silicate layers and the polymer material. Additionally preferred association helps to optimize synthetic routes and improves overall performance characteristics of the resulting end product. As an illustration, it has been found that many silicate compositions of this invention exhibit excellent nanoscale dispersion of the inorganic layers in many commodity and high- performance polymer resins.

0017It has also been found that preferred nanocompositions of this invention exhibit performance characteristics that will positively impact many applications. For example, many of the nanocomposites disclosed herein offer very favorable melting and heat distortion temperatures. These and other important characteristics discussed below help make the nanocomposites and other exemplified silicate compositions well-suited for long-term or short-term use above about 150°C. As will be discussed below, many particularly preferred nanocomposites provide for even higher thermal stability in excess of about 200°C with about 250°C to about 400°C or more being useful for many applications.

0018It will be understood that the enhanced use temperature provided by many preferred nanocomposites of this invention can be determined by one or a combination of strategies including heat distortion tests referenced below.

0019Accordingly, in one aspect, the invention provides an inorganic layered silicate that includes at least one organophilic agent associated with the silicate. A preferred organophilic agent is a high temperature organic surfactant. In one embodiment, the surfactant comprises at least one onium salt, preferably at least one ammonium, phosphonium or sulfonium salt, which onium salt is non-covalently bond to the silicate. Preferred non-covalent bonding is through one or more ionic bonds between the onium salt and the inorganic layered silicate. Also contemplated are acceptable salts of the inorganic layered silicate.

0020In a particular embodiment, the onium salt is present in a molar amount that is preferably less than the molar amount of exchangeable silicate ions in the composition. That is, the milliequivalent amount of the onium salt in the silicate composition is preferably less then the milliequivalent amount of exchangeable ions in the silicate. In a more particular embodiment, the onium salt is at least one of a suitable ammonium salt, preferably an alkyl ammonium salt; or at least one of a phosphonium or sulfonium salt.

0021In embodiments of the invention in which the silicate composition includes at least one inorganic layered silicate and at least one of the foregoing onium salts non- covalently bond thereto, the association between the silicate and surfactant can be achieved by one or a combination of strategies including use of standard ion exchange methods. Particular use of the methods involves contacting the inorganic layered silicate and the surfactant under suitable ion exchange conditions that facilitate non- covalent binding between the onium salt and the silicate. Optionally, the ion exchange methods can be used to estimate or quantify the molar amount of ions exchanged.

0022If desired, particular silicate compositions in accord with this invention can be referred to the molar amount or milliequivalent of the ions exchanged.

0023For example, in one embodiment, the ratio of the molar amount of the onium salt to the molar amount of the exchangeable ions in the silicate is at least about 0.1 to at least about 10 , preferably between from about 0.1 to about 1, with about 0.25 to about 1 typically being preferred. Reference herein to a particular silicate composition having an "underexchanged" silicate, silicate matrix, or related phrase means that the molar amount of the onium salt is generally less than the molar amount of the exchangeable ionic sites in the silicate. In embodiments of the invention in which the silicate composition includes more than one onium salt and optionally more than one type of inorganic layered silicate, it will be understood that the exchange reference is made with respect to all the onium salts and all the layered silicates in the composition.

0024Preferred high temperature organic surfactants will include at least one onium salt suitable for high temperature use. Preferably, all the onium salts in the surfactant are suitable for use at the high temperature. As discussed, a particular onium salt is a phosphonium salt which salt can be alone or in combination with at least one other onium salt such as the sulfonium salt and the ammonium salt. A more particular ammonium salt is an alkyl ammonium salt such as those referenced below. In embodiments of the invention in which silicate composition includes the alkyl ammonium salt, that salt is preferably underexchanged although for some applications it may be useful to overexchange that salt for the exchangeable silicate.

0025Further provided by the invention are compositions that include at least two of the inorganic layered silicates disclosed herein, preferably between from one to about five of the silicates and more preferably about two of such inorganic layered silicates. Such compositions find use in a variety of settings including those requiring a combination of inorganic layered silicates to achieve a desired performance result.

0026Also provided by this invention are silicate compositions that include at least one of the inorganic layered silicates and at least one organically modified layered aluminosihcate (hereinafter "ORMLAS"). Particular silicate compositions include between from one to about 5 of the inorganic layered silicates, preferably one of same, and between from one to about 5 ORMLAS, preferably one of same. Thus it is an objective of this invention to provide silicate compositions that include a mixture of silicate types including those with one type of inorganic layered silicate type and one type of ORMLAS.

0027Unless stated otherwise, reference herein to "ORMLAS" is meant to encompass one type of organically modified layered aluminosilicates.

0028In another aspect, the present invention provides particular silicate compositions referred to as nanocomposites. In one embodiment, the nanocomposites include at least one of the inorganic layered silicates discussed herein or at least one of the ORMLAS. In this example of the invention, the nancomposite also includes at least one suitable polymer material. Alternatively, the nanocomposite can include at least one of the inorganic layered silicates and at least one of ORMLAS and at least one desired polymer material. As discussed below, preferred nanocomposites have a heat distortion temperature of at least about 150°C. Use of particular components in a nanocomposite or other silicate composition of this invention will be guided by several parameters including the specific performance characteristic(s) desired, and intended use.

0029As mentioned, a wide spectrum of polymer materials are compatible with the silicate compositions provided by this invention. More specific polymer materials include those appropriate for intercalation within layers of the inorganic silicate. Preferred are polymer materials capable of providing a d-spacing between silicate layers of at least about 18 Angstroms as determined by conventional X-ray diffraction (XRD). For disclosure relating to XRD, see X-ray Diffraction Methods in Polymer Science, L. E. Alexander, Wiley, N.Y., pp. 137-229 (1969), hereby incoφorated by reference.

0030Thus, in one embodiment, the invention provides silicate compositions and especially nanocomposites that exhibit a d-spacing between the silicate layers of at least about 18 Angstroms, preferably at least about 18 to about 19 Angstroms. Preferred inorganic layered silicates for use in this embodiment of the invention are well-suited for intercalating polymer material, including multiple polymer materials.

0031Additional nanocomposites of the invention include at least one of the inorganic layered silicates disclosed herein and at least one of the polymer materials. More particular polymer materials suited for use in this embodiment include those appropriate for exfoliation of layers of the silicate. In this example of the invention, the nanocomposition exhibits a preferred d-spacing between silicate layers of at least about 18 Angstroms as determined by the XRD with between about 18 to about 19 Angstroms often being preferred.

0032As discussed, many preferred silicate compositions in accord with this invention will be acceptable for long-term or short-term use in excess of about 150°C. Especially preferred nanocomposites will be suited for long-term or short-term use at a high temperature of at least about 200°C with at least about 250°C to about 400°C being preferred for many applications. Methods for detecting and quantifying a wide variety of parameters relating to thermal stability are known in the field and include conventional heat distortion tests.

0033Additionally preferred silicate compositions include those nanocomposites that having good or "high" barrier properties. In this embodiment of the invention, the nanocomposites typically provides for the good barrier properties at temperatures below about 150°C. High barrier properties are especially useful when the silicate composition is included in at least part of a manufactured article including up to essentially the entire article. As will be appreciated, the performance characteristics of many manufactured articles such as those relating to the automotive, aerospace, electronic, pharmaceutical, apparel, food and beverage packaging industries will be enhanced by having good barrier properties to a solute such as a liquid, gas; or mixture thereof.

0034More particular nanocomposites suitable for use in the manufactured articles help provide for a significant permeability barrier to diffusion of at least one of: oxygen, nitrogen, carbon dioxide, water vapor, a noble gas such as helium; or a mixture thereof. This feature of the invention has many advantages including providing manufactured articles with capacity to reduce or eliminate gas diffusion as determined by standard testing procedures described below.

0035More particular examples of the manufactured article include or consist of those having an enclosed space with a gaseous, solid or semi-solid material intended to be essentially confined in that space. In this embodiment, the manufactured artricle may include or consist of a structure that is particularly designed to exclude or retain a material such as a liquid, gas; or mixture thereof. Particular structures are referred herein as a "cushion", "bladder", "bag" "pillow" "base insert" or like term to denote intention to reduce or eliminate impact force to which the manufactured article may be exposed during construction or use. Preferred bladders are gas bladders that include at least one gas enclosed by at least one of the silicate compositions of this invention. Preferred gas bladders provide several uses and advantages including improved impact absoφtion, directional stabilization, and lightness, particularly when used in footwear applications.

0036Future nanocomposites in accord with this invention include those well-suited for use in pharmaceutical packaging materials such as "blister packs". In this embodiment, the blister pack is preferably adapted to hold a pharmaceutical composition (e.g., a pill) and can significantly exclude (or retain) the solute from the composition.

0037Additionally preferred silicate compositions and particularly nanocomposites will exhibit at least one of the following performance characteristics: good thermal stability, excellent heat distortion temperature, suitable mechanical strength, good interfacial design, and polymer compatibility. Additionally preferred are nanocomposites that have favorable interlayer d-spacing for those embodiments in which intercalation of the polymer material is useful.

0038Also preferred are nanocomposites featuring at least one of the following particular performance characteristics: good impact resistance, excellent tensile modulus, good flame resistance, and suitable glass transition temperature. Especially preferred are nancomposites featuring at least two of these characteristics and more preferably most or all of them. As mentioned, presence of one or more of the performance characteristics in a particular nanocomposite will be guided by several parameters including intended use.

0039As discussed, the silicate compositions of this invention provide many significant uses include use in more particular articles of manufacture. Illustrative of such articles include those mentioned above and including these suitable for use in the container (e.g., beverage) clothing and footwear industries. In another aspect, the present invention provides highly useful ORMLAS and ORMLAS related materials. Particular ORMLAS of interest include at least one inorganic layered silicate, preferably a synthetic inorganic layered silicate; and at least one organophilic agent, preferably an organic compatibilizing agent, covalently attached to the layered silicate. Preferably, the inorganic layered silicate has an aspect ratio of from between about 10 to about 1000 as determined by transmission electron microscopy (TEM).

0040Additionally preferred ORMLAS are made by the "sol-gel" synthetic process discussed below.

0041Additionally preferred ORMLAS feature a d-spacing between the silicate layers of at least about 20 Angstroms.

0042The invention further provides a composition that preferably includes between from about two to about five ORMLAS, more preferably about two ORMLAS. For many applications, a silicate composition that includes one ORMLAS will be useful.

0043Preferred inorganic layered silicates for use in accord with this invention are generally negatively charged clay minerals that can undergo isomoφhous ion exchange. The silicates generally differ from one another in characteristic properties such as particle size, density and distribution of negative charges. More specific silicates are naturally-occurring or synthetic clay or clay-related minerals. Many silicates can be readily obtained from commercial vendors.

0044More preferred clay minerals for use with this invention are fully compatible with a pre-determined polymer material and are particularly amenable to high temperature use or processing steps.

0045In some embodiments of this invention such as those involving ORMLAS, use of chemically modified silicates will be generally preferred. In a particular embodiment, that chemical modification is covalent bonding between the silicate and at least one suitable organophilic agent, preferably at least one compatiblizing agent.

0046Preferred organophilic agents are often referred to herein as "compatibilizing" agents to denote capacity to provide good contact between layered silicates and polymer material. A more preferred compatibilizing agent is generally appropriate for high temperature applications and facilitate combination of the silicate and the polymer material as a single compound. Additionally preferred compatibilizing agents optionally help to optimize d-spacing between intercalated silicate layers to a particular value or range of values as required.

0047More specifically preferred compatibilizing agents for use with the inorganic layered silicates of this invention include at least one of an onium salt as discussed previously or an organo-silane. Preferred onium salts include sulfonium, phosphonium and ammonium. Preferred organo-silane compounds include those materials which can render an ORMLAS thermally stable and significantly organophilic. Illustrative organo-silane compounds include organically functionilized silanes and particularly alkylsilanes and alkoxy silanes. As discussed below, it has been found that modification of the organo-silane, i.e., by introducing non-aliphatic groups can facilitate production of silicate compositions with very useful performance characteristics.

0048In a particular embodiment of this invention, the nanocomposite includes at least one ORMLAS disclosed herein, preferably one ORMLAS and at least one suitable polymer material including a polymer blend or alloy. In a more particular embodiment, the polymer material is well-suited to intercalate within layers of the ORMLAS. Alternatively, the polymer material can be selected for exfoliation of layers of the silicate. The nancomposite can optionally include at least one of the inorganic layered silicates disclosed herein, e.g, to enhance or to provide for one or more desired performance characteristics. Also envisioned is a nanocomposite that includes matrix regions in which the polymer material is intercalated and other regions in which the silicate layers are essentially completely exfoliated within the polymer matrix.

0049As will be understood to those of skill, choice of a particular component or group of components for use in a desired silicate composition will be guided by recognized parameters including intended use and the performance characteristic(s) desired. More specific component choices will be guided by at least one of the following considerations: thermal stability, barrier property, and mechanical strength.

0050In another aspect, the invention provides a range of manufactured articles that include or consist of at least one of the silicate compositions disclosed herein. In one embodiment, the article includes at least one of the nanocomposites, preferably between from 1 to about 5 nanocomposites, with one nanocomposite being preferred for many uses. In a more particular embodiment, the article is capable of posing a significant permeability barrier to diffusion of at least one of the following: oxygen, nitrogen, carbon dioxide, water vapor, a noble gas; or a mixture thereof. Preferably, the noble gas is helium. Highly preferred manufactured articles include or consist of those nanocomposites and other optimally silicate compositions that can confer the barrier properties as well as other desired performance characteristics.

0051More preferred is an article of manufacture that includes at least one of the silicate compositions and particularly at least one of the nanocomposites disclosed herein, which article has a preferred permeability to oxygen of at least about 1.5 to about 2-fold lower than the oxygen permeability of the neat polymer. Of course, in embodiments in which the polymer material is a mixture such as a polymer blend or polymer alloy, meaningful comparisons will often be made between the article made with the polymer mixture instead of the neat polymer.

0052Additionally preferred articles of manufacture include those silicate compositions that can provide relatively lightweight characteristics as that term is understood in this field when compared to the same or related article employing prior silicate compositions.

0053In another aspect, the invention provides a variety of useful methods for making an inorganic layered silicate as provided herein. Preferably, that silicate includes non-covalently bound thereto at least one of the organophilic agents mentioned and possibly at least one high temperature organic surfactant. In one embodiment, the method includes at least one and preferably all of the following steps: a) admixing the inorganic layered silicate in a suspension of aqueous or organic solvent, b) contacting the solution with the surfactant under conditions which enable formation of a precipitate in the solution; and c) collecting the precipitate from the solution in which the precipitate includes the inorganic layered silicate non-covalently bound to the high temperature organic surfactant.

0054In one embodiment of the method, the surfactant comprises at least one onium salt as discussed previously. Preferably, the method involves use of at least one phosphonium salt and preferably one phosphonium salt.

0055In another embodiment, the surfactant comprises at least one ammonium salt, preferably an alkyl ammonium salt. In a more preferred embodiment the molar amount of the onium salt is less than the molar amount of the exchangeable ions in the silicate. Methods for determining the exchangeable ions include the conventional ion exchange methods discussed above.

0056In a more particular embodiment of the method, the surfactant includes a combination of acceptable onium salts, preferably at least one of a suitable phosphonium salt, and an ammonium salt, preferably an alkyl ammonium salt. In another aspect, the present invention provides methods for making the nanocomposites disclosed herein. In one embodiment, the methods include combining at least one inorganic layered silicate with at least one suitable polymer material. Preferred combination involves polymer intercalation or exfoliation within layers of the inorganic layered silicates. Preferred nanocomposites for use in the method include those mentioned previously.

0057More particular methods for making the nanocomposites are discussed below. Such methods include polymer melt and solution based methods that in optimal practice help to manifest the performance characteristics desired.

0058In another aspect, the invention provides methods for making an organically modified layered aluminosilicate (ORMLAS). In one embodiment, the method includes at least one and preferably all of the following steps: a) combining in a basic and alcoholic aqueous solution at least one metallic halide (e.g., Al, Mg, Ni, or Fe halide) with at least one organo- siloxane represented by the following general formula I:

0059R₂ I R Si-R₃

R4

0061in which Rl is a substituted or unsubstituted alkyl, alkenyl, alkynyl, or alkoxy group, and each of R2, R3, and R4 is independently an alkoxy group the same or different, b) producing a precipitate in the solution; and c) collecting the precipitate from the solution in which the precipitate includes the ORMLAS. In one embodiment, the method preferably includes combining in the solution at least one organo-siloxane having at least one carbon chain shorter than the organo- siloxane of Formula I. By the term "shorter" is meant that the organo-siloxane has fewer carbon atoms than the organo-siloxane of Formula I, generally from between one to about 10 carbon atoms shorter.

0062In another embodiment of the method, the organo-siloxane of Formula I preferably includes at least one substituted or unsubstituted alkyl group. In this example of the invention, the method further includes combining in the solution at least one organo-siloxane as represented in Formula I except that the organo-silane will include at least one non-aliphatic group.

0063The foregoing method is generally flexible and can be readily modified to suit intended use. For example, the method can be used with one organo-silane or a combination thereof e.g., to achieve a desired performance characteristic.

0064The invention also provides more specific methods for making a nanocomposite in which an extruder or related implementation is preferably employed. In one embodiment, the methods include at least one and preferably all of the following steps: a) combining in a suitable extruder at least one inorganic layered silicate disclosed herein, e.g., one ORMLAS, with at least one polymer material, the combining being under conditions which enable melting of the polymer material in the extruder, b) adding the inorganic layered silicate to the melted polymer material in which the addition is under conditions which enable effective contact between the layered silicate and the polymer material, c) mixing the inorganic layered silicate and the melted polymer material; and d) producing the nanocomposite from the extruder. In one embodiment, the method includes use of between from one to about five of the inorganic layered silicates disclosed herein. However, for most applications, use of one of the silicates, ie., one of the inorganic layered silicates or one ORMLAS will be preferred. In this example, the inorganic layered silicate preferably includes at least one of the high temperature organic surfactants non- covalently attached to the silicate. Preferred surfactants are the phosphonium salt alone or in combination with at least one other onium salt, e.g, sulfonium salt, ammonium salt and preferably alkyl ammonium salt.

0065In another embodiment, the method includes use of between from one to about five ORMLAS with one of the ORMLAS being preferred for many applications. In this example of the invention, the ORMLAS preferably includes at least one of the organic compatibilizing agents discussed previously. In a further embodiment of this method, ORMLAS can be optionally combined in the extruder with between from one to about five of the inorganic layered silicates and preferably one of the silicates disclosed herein.

0066Components for use in the extruder method can be added to the extruder together or separately as needed. The order in which the extruder components are combined is not critical provided that the nanocomposite has the desired performance characteristics.

0067In another embodiment, the invention provides solution based methods for making the silicate compositions described herein and particularly certain nanocomposites. In general, such solution based methods will often be appropriate in settings where the desired polymer material produces noxious gas and/or where use of a specific polymer material at the high temperature may pose risk to personnel. Such methods are additionally preferred when very good dispersion of the clay minerals is required.

0068More particularly, the invention provides solution based methods for making the nanocomposite that include at least one and preferably all of the following steps: a) contacting at least one clay mineral with a solvent suitable for the polymer material selected, b) exposing the solution to ultrasound conditions sufficient to suspend the clay mineral in the solvent, c) contacting the solution with at least one polymer material in which the polymer material is preferably in liquid form, d) mixing the suspension and the polymer material for at least several hours up to a few days; and d) removing the solvent from the suspension to produce the nanocomposite, e.g., in a film or related form.

0069Additional methods for making the silicate compositions are provided below and include methods involving multiple processing techniques. In general, the techniques are formulated to enhance desired performance characteristics including long-term high temperature use. For example, practice of the foregoing methods is assisted by innovative chemical design of the organic-inorganic interface in the compositions to be made. In preferred embodiments, the methods employ more thermally stable surfactants/compatibility agents, and more thermally stable synthetic organically-modified layered-silicate reinforcements to make the silicate compositions. These approaches are compatible with several synthetic manufacturing methods including the solution-based methods and solvent-free melt or melt-related techniques discussed above.

0070The invention also provides more specific polymer melt process conditions for making (compounding) various nanocomposites in accord with this invention. For example, in a more specific embodiment, the methods include at least one and preferably all of the following steps: a) feeding components to be compounded into a suitable extruder implementation such as a single screw extruder and preferably a twin- screw extruder, in which the components are fed at a pre-determined rate, the feeding being under conditions that enable the neat polymer material to achieve essentially melt temperature therein, b) combining the components inside the extruder under conditions that enable efficient mixing therebetween and reduce or eliminate any trapped gas; and c) producing the nanocomposite from the extruder implementation.

0071More particular process conditions for compounding the nanocomposites of this invention are provided below. Choice of particular components to use in the method as well as more specific feeding and combining steps will be guided by intended use of the nanocomposite to be made including the performance characteristics desired.

0072As discussed, the invention provides a wide variety of specific articles of manufacture that preferably include at least one of the nanocomposites disclosed herein. More preferred articles include from one to about five of the nanocomposites with one of the nanocomposites being useful for most applications. In a preferred embodiment, the article is footwear adapted for athletic or related use.

0073In another aspect, the invention includes methods for making a manufactured article that includes at least one of the nanocomposites provided by this invention. In one embodiment, the methods include adding at least one nanocomposite to at least one component intended for the article and assembling the component to make the article. Preferred methods involve making footwear adapted for athletic use.

0074In addition to the foregoing, the invention provides additional uses and advantages which will be apparent to those with skill in this field.

0075For example, in particular embodiments, the invention is fully compatible with use of essentially environmentally- riendly and solvent- free polymer melt processing techniques. In addition, many of the present silicate compositions including particular nanocomposites feature thermally stable natural clay systems having, e.g., organic phosphonium surfactants

0076Still further, the invention helps to solve several problems that have plagued prior attempts to make and use silicate compositions effectively. In particular, many prior nanocomposites have been found to exhibit undesired plasticization. This problem can be substantially reduced or even totally avoided by significantly lowering the organic content of the clays employed in the composition. That is by lowering the organic content of the nanocomposite by between from about 10% to about 90% relative to the organic content of recognized alkyl ammonium nanocomposites, the plasticization can be avoided. The silicate compositions of this invention and particularly the preferred nanocomposites substantially avoid undesired plasticization.

0077In particular, the invention avoids undesired plasticization in several ways. For example, it provides methods that can reduce this phenomenon by using partial replacement of non-aliphatic groups for the long chain alkyls typically used to make the compositions. This approached can be adapted for use with the phosphonium exchanged clays for which a lower than 100% exchange capacity is often useful. It is believed that these and other methods disclosed herein can provide a silicate composition and particular a nancomposite that has a higher heat distortion without unduly compromising the T_g due to plasticization.

0078Also, it is believed that many nanocomposites of this invention including those that employ underexchanged clay will be significantly superior to compositions that include the overexchanged clays.

0079These and other advantages facilitate use of the invention in a variety of settings. For example, the ORMLAS generally include "built-in" surfactants that help to minimize or eliminate presence of harmful alkyl ammonium surfactants. These advantages facilitate use of nanocomposites and related silicate compositions in important applications such as in food or beverage packaging materials. In preferred embodiment, the invention thus provides recyclable and more cost-effective packaging materials that find use in the replacement of previously unrecyclable multilayer plastic packages.

0080The invention also provides nanocomposites featuring a good barrier to at least one of a gas or liquid solute. In one embodiment, the invention provides what is sometimes referred to herein as a "high barrier" nanocomposite or a related phrase. In this example of the invention, the nanocomposite decreases the transmission rate of the solute through the nanocomposite as determined by standard testing procedures. Such nanocomposites have a wide spectrum of useful applications including use in manufactured articles in which good retention or exclusion of the solute is desired. In one embodiment, the manufactured article includes or consists of at least one of the nanocomposites provided herein and possesses an effective permeability barrier to the solute.

0081As will be discussed below, such high barrier nanocomposites have a wide variety of useful applications including use in manufactured articles such as "blister" or "bubble" packs.

0082In another aspect, the invention relates to the preparation of polyolefin layered silicate polymer nanocomposite materials. In one embodiment, the materials include suitable amounts of at least one of and preferably all of the following: polyolefin; polyamide, what is referred to herein as "functionalized grafted polyolefin", organoclay, and synthetically formulated organoclay preferably formed by self-assembly techniques. In this example of the invention, the functionalized grafted polyolefin typically plays the role of a compatabilizer in embodiments in which polyolefin and polyamide phases are non-compatible particularly in certain compounding blends. These and other uses and advantages of the invention will become more apparent from the following disclosure including the drawings, examples and the claims.

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BRIEF DESCRIPTION OF THE DRAWINGS

0085Figure 1 A is a schematic drawing showing a prior inorganic layered silicate with alkyl ammonium surfactant.

0086Figure IB is a schematic drawing showing an inorganic layered silicate of the invention with tetraphenyl phosphonium surfactant.

0087Figure IC is a schematic drawing of an ORMLAS.

0088Figure 2 is a chemical representation of tetraphenyl phosphonium surfactant.

0089Figure 3 is a schematic drawing of types of polymer-layered silicate nanocomposite structures.

0090Figure 4 is a table of recognized properties of nylon-6 and layered silicate- nylon nanocomposites. See Giannelis, E.P. (1996), as discussed infra.

0091Figure 5 is a graph showing an X-ray Diffraction (XRD) pattern for aluminooctylsilsesquioxane (C₈ORMLAS).

0092Figure 6 is a graph showing an XRD pattern for aluminododecylsilsesquioxane (Cι₂ORMLAS).

0093Figure 7 is a graph showing an XRD pattern for alummooctadecylsilsesquioxe (CisORMLAS).

0094Figure 8 is a transmission electron microscopy (TEM) image of Al- dodecylsilsesquioxane (Cι₂ORMLAS).

0095Figure 9 is TEM image of Al-Octadecyl Silsesquioxane (C18

0096ORMLAS)/Ultem Nanocomposite. Figure 10 is a TEM image of tetraoctyl phosphonium Exchanged Clay/Ultem Nanocomposite

0097Figure 11 is a TEM image of Atapulgite/Ultem Nanocomposite.

0098Figure 12 is a table showing a list of alkyl and phenyl ORMLAS materials along with observed d-spacings.

0099Figure 13 is a graph showing thermo-gravametric analysis (TGA) of dodecyl silsesquioxane under nitrogen atmosphere.

0100Figures 14A-G are XRD results for selected Al-silsesquioxanes.

0101Figures 15A-C are powder XRD patterns of (15 A) 5 wt.% Al n-Dodecyl silsesquioxane with Nylon powder before extrusion, (15B) 7 wt. % Al n-Dodecyl silsesquioxane with Nylon powder before extrusion, and (15C) 7% Al n-Dodecyl silsesquIoxane-Nylon nanocomposite formed after extrusion.

0102Figures 16A-B are TEM images showing exfoliation of Al- dodecylsilsesquioxane nylon nanocomposite.

0103Figures 17 A-B are graphs showing Differential Scanning Results (DSC) of Nylon-6 and Nylon ORMLAS compositions.

0104Figures 18A-C are graphs showing XRD spectra for montmorillonite ion- exchanged with various phosphonium cations.

0105Figures 19 A-B are graphs showing XRD patterns of extrusion product of various phosphonium exchanged clay and Nylon nanocomposites.

0106Figure 20 is a graph showing DMA curves for a) neat Udel and b) Udel nanocomposite. Figure 21 is a graph showing results of a dynamic mechanical analysis for Nylon-6 and Nylon 6 -ORMLAS nanocomposite.

0107Figures 22A-C are graphs showing thermal stability of various materials. Fig.

010822 A Dihydrotallowdimethyl ammonioum exchanged montmorillonite; Fig. 22B. Tetraoctyl phosphonium exchanged montmorillonite; Fig. 22C) aluminum octadecyl silsesquioxane (Cι₂ ORMLAS).

0109Figure 23 is a schematic drawing showing a high barrier nanocomposite of this invention. In the drawing, layered silicate is shown as a plurality of horizontal lines embedded in polymer material. Retarded solute movement through the nanocomposite is exemplified by the arrow.

0110Figure 24A-B are graphs showing X-ray Diffraction (XRD) patterns. Figure

011124A is an XRD of exchanged Na⁺-montmorillonite. Figure 24B to XRD of exchanged Na⁺-montmorillonite.

0112Figure 25 A-B are graphs sharing X-ray Diffraction (XRD) patterns. Figure 25 A is an XRD of 5% Clay-PET nanocomposite. Figure 25B is an XRD of 10% Clay-PET nanocomposite.

DETAILED DESCRIPTION OF THE INVENTION

0114As discussed, the present invention features a wide spectrum of compositions that include at least one type of inorganic layered silicate and at least one type of organophilic agent associated with the silicate. That association is preferably through covalent or non-covalent bonding between the agent and the silicate layer. In one embodiment, the invention provides inorganic layered silicates that include at least one non-covalently bound high temperature organic surfactant which surfactant includes at least one onium salt. Additionally provided are organically modified layered aluminosilicates (ORMLAS) that include at least one covalently attached organic compatibilizing agent. In more particular embodiments, the invention provides a range of highly useful nanocomposites that include at least one of the inorganic layered silicates and optionally at least one of the ORMLAS which nanocomposite further includes at least one suitable polymer material. Alternatively, the nanocomposites include at least one ORMLAS and optionally at least one of the inorganic layered silicates with the polymer material.

0115In general, the silicate compositions feature exceptional performance characteristics such as better thermal stability, good mechanical strength and favorable gas barrier properties with respect to a solute such as a gas, liquid, or mixture thereof. Of particular interest are those nanocomposites that have at least one of these properties as well as more specifically desirable performance characteristics such as long-term high temperature use.

0116The present invention provides a variety of high temperature and lightweight silicate compositions that have highly useful applications. The invention provides many useful alternatives to the prior practice of making silicate compounds which has typically involved use of alkyl ammonium salts and related agents. As discussed, the alkyl ammonium salts may not always provide silicate compositions with optimal performance characteristics.

0117For example, in one embodiment, the invention provides new silicate compositions and particularly nanocomposites with exceptional long- or short-term high temperature use. The compositions typically include the polymer material with at least one compatibilzing agent covalently linked to the silicate structure (ie., an ORMLAS). By covalently linking the compatibilizing agent to the layered silicate structure in accord with this invention, better performance characteristics can usually be achieved. In contrast, many prior silicates employ non-covalently bound alkyl ammonium salts which do not always provide these characteristics.

0118In addition, the invention provides silicate compositions and particularly nanocomposites that include at least one onium salt and especially the phosphonium salt alone or in combination with at least one other onium salt. In a particular embodiment, it has been found that non-covalently linking the phosphonium salt to the silicate layer generally improves performance characteristics and provides for better synthesis of the silicate composition.

0119Unless otherwise indicated, the term "high temperature" or related phrase when used to reference a silicate composition of this invention will be understood to mean a preferred temperature of at least about 150°C, preferably between from about 200°C to 450°C, and more preferably between from about 250°C to about 400°C.

0120As also discussed, the invention provides highly useful synthetic methods for making the silicate compositions of this invention. As an illustration, the invention provides two essentially direct melt processible techniques for making the preferred nanocomposites. Practice of these methods can enhance performance characteristics including the thermal stability from prior limits of about 150°C, to about 250°C - 300°C up to about 400°C.

0121Further provided are several methods for making ORMLAS that generally involve combining specific layered silicates and the organic compatibilizing agent in a single chemical compound. This aspect of the invention renders the ORMLAS thermally stable, exceptionally organophilic and compatible with a range of suitable polymer materials. It is believed that the ORMLAS and ORMLAS-related compositions provided by this invention include some of the most thermally stable silicate-organic interfaces known in the field. Significantly, the ability of the present methods to form layered structures with the facilitates effective use of this invention in a wide variety of applications.

0122By the term "ORMLAS-related" composition is meant ORMLAS plus at least one inorganic layered silicate as provided herein.

0123See Examples 1-2 below describing how to make and use a variety of

0124ORMLAS. In particular, it will be readily apparent that the recognized stability of Si-C bonds provides an effective chemical framework for using the silicate compositions in settings were superior performance characteristics are needed.

0125As discussed, specific silicate compositions of this invention can be manufactured from one or a combination of clay minerals including what is referred to in the field as hard clay, soft clay, talc; or a mixture thereof. Preferred clay minerals include naturally-occurring or synthetic clay as well as clay mixtures. In embodiments in which the silicate composition includes at least one naturally- occurring clay, characteristics of the clay can be modified by non-covalently associating therewith at least organophilic agent and preferably at least one of the high temperature use surfactants discussed previously.

0126More preferred layered materials for use in this invention may vary widely but generally include phyllosilicates and related materials. Illustrative materials are smectite clay minerals such as montmorillonite, nontronite, sepiolite, atapulgite, beidellite, volkonskoite, hectorite, saponite, sauconite, magadiite, and kenyaite; vermiculite; and the like. Other useful layered materials include illite minerals such as ledikite and admixtures of illites with the clay minerals. Other useful layered materials, particularly useful with anionic polymers, are the layered double hydroxides. See e.g, W. T. Reichle, J. Catal, 94 (12985) 547). Many of these clays have positively charged layers and exchangeable anions in the interlayer spaces. Additional phyllosilicates include the 2:1 type having a negative charge on the layers ranging from about 0.25 to about 0.9 charges per formula unit and a commensurate number of exchangeable cations in the interlayer spaces. More preferred layered materials are smectite clay minerals such as montmorillonite, nontronite, beidellite, bolkonskoite, hectorite, saponite, sauconite, sepiolite, fluorohectorite, atapulgite, laponite magadiite, and kenyaite. Generally prefened smectites include aluminosilicates, magnesiosilicates as well as mixtures thereof. See also U.S. Pat. No. 5,385,776 for other clay minerals suitable for use with this invention. The amount of clay mineral used in a silicate composition of this invention will vary depending on intended use and particularly by the performance characteristics desired. For example, an amount of clay mineral (or combination of clay minerals) less than about 0.5% by weight of the matrix will be useful for many applications. For other applications however, the amount of clay mineral may approach several parts per million or less. Preferably the amount of a particular clay mineral in a silicate composition will be from between about 0.1% by weight to about 10% by weight with between from about 0.1% by weight to about 0.5% by weight of the matrix being preferred for many applications.

0127More particularly preferred is clay levels from about ppm level up to about 10% clay in the polymer matrix.

0128Preferred polymer materials for use in the present invention are substantially intercalated within the inorganic layered silicate or exfoliated as discussed previously. More particular layered silicates are often in the form of platelet particles. As used herein, "platelet particles" are particles that usually have two relatively flat opposite faces wherein the thickness of which is the distance between the faces, which is relatively small compared to the size of the faces.

0129Preferred platelet particles in accord with this invention typically have the thickness of the individual layers in the silicate, or small multiples less than about 10, preferably less than about 5 and more preferably less than about 3 of the layers, and still more preferably 1 or 2 layers. The other dimensions of the platelet particles may vary greatly depending on intended use and the specific performance characteristics desired. However in embodiments employing the clay minerals, preferred particle faces are roughly round or oblong having average diameters between about 10,000 Angstrom and about 50 Angstrom, such that the aspect ratio length/thickness ranges from about 1000 to about 1.

0130For the puφoses of the present invention, the average diameter is defined as the diameter of a circle having an area equal to the surface area of one broad surface face of the platelet shaped particle. The average diameter is determined from particle surface area by standard methods such as use of an appropriate analyzer system. In the preferred embodiments of the invention, the average thickness of the platelet particles is equal to or less than about 20 Angstrom with a maximum thickness of 50 Angstrom and the average diameter is between 5,000 Angstrom and 100 Angstrom with a maximum diameter of 10,000 Angstrom. More preferably, the average thickness is equal to or less about 15 Angstrom with a maximum thickness of 25 Angstrom and the average diameter is from about 2,000 Angstrom to about 200 Angstrom with a maximum diameter of 5,000 Angstrom. Even more preferably, the average thickness is from about 1 to about 15 Angstrom with a maximum thickness of 25 Angstrom and the average diameter is from about 2000 Angstrom to about 200 Angstrom with a maximum diameter of 5,000 Angstrom.

0131A still more preferred clay mineral for use with the present invention has an aspect ratio of between from about 50 to about 1000 and more preferably a thickness of about lnm As mentioned, naturally-occurring clay minerals exchanged with at least one onium salt, preferably a phosphonium salt alone or in combination with at least one of an alkyl ammonium or sulfonium salt are often preferred.

0132More particular examples of the foregoing include preferred phosphonium exchanged montmorillonite clays provided below in Example 3. These particular silicate compositions include phosphonium salts having organophilic moieties such as long chain alkyl and aryl groups. It has been found that use of phosphonium salts with the organophilic moieties positively impacts the invention in several respects including improving contact between the inorganic layers and a wide range of polymer materials. That is, the inorganic layered silicate "looks" more like the polymer material for which effective intercalation or exfoliation is desired.

0133Additionally prefened are layered silicates that have been chemically modified with at least one compatibilizing agent as provided herein. For example, use of long chain alkyls in the synthesis of ORMLAS usually improved dispersion within polymer materials such as Ultem. Particular phosphonium clays of this invention can be synthesized with alkyl groups that are longer than those used in the field. Preferred are longer alkyl groups that help to "prop" the silicate layers apart better (ie. give enhanced d-spacing), thereby allowing for better intercalation / exfoliation with the various polymers, polymer blends or polymer alloys.

0134By the term "compatibilizing agent" or related phrase is meant a prefened organophilic agent that is capable of being covalently linked to the inorganic layered silicate and which facilitates effective intercalation or exfoliation in that silicate. A particular agent is "compatible" to the extent that it facilitates favorable interactions between the platelet particles and the matrix polymer material. Without wishing to be bound to theory, especially preferred compatibilizing agents in accord with this invention are believed to provide for at least one of the following desirable matrix properties: similar cohesive energy densities for the polymer material and the derivatized platelets, similar or complimentary capacities for dispersive, polar, or hydrogen bonding interactions, or other specific interactions, such as acid/base or Lewis-acid Lewis-base interactions. Additionally, good compatibilization helps to improve contact and particularly dispersion of the platelet particles in the matrix and an improved percentage of delaminated platelets with a thickness of less than about 50 Angstrom.

0135It is one achievement of this invention to enhance incoφoration of layered silicates and clay minerals with desired polymer materials, thereby providing silicate composition with superior performance characteristics.

0136As discussed, particular inorganic layered silicates of this invention include at least one high temperature organic surfactant non-covalently attached to the silicate in which the surfactant includes at least one phosphonium group. By the term "high temperature organic surfactant" or related phrase is meant thermal stability to decomposition to at least about 200°C. The inorganic layered silicates having the surfactant have a prefened d-spacing of from between about 10 to about 50 Angstroms as determined by XRD or a related test.

0137Prefened silicate compositions of this invention and particularly the disclosed inorganic layered silicates and ORMLAS are compatible with a wide variety of polymer materials.

0138More particular polymer materials are polymers such as those suitable for polymerization with a wide variety of clay minerals. Prefened polymers can be adapted in accord with this invention for long-term high temperature use.

0139Additionally prefened are polymers that provide at least one of good thermal stability, excellent mechanical strength, and good barrier properties as disclosed herein. Additionally prefened polymers are generally compatible with a wide variety of melt and solution processing techniques.

0140More specific polymers include but are not limited to high temperature polymers such as thermoplastic polymers, e.g., thermoplastic polyesters. Illustrative of such polyesters include liquid crystalline polymers such as wholly aromatic polyesters and copolyesters such as Xydar™ and Vectra™, PET (polyethylene tetraphthalate), PBT, poly(butylene tetraphthalate), PPS (polypropylene sulfide), and PCT (polycyclohexylene dimethylene tetraphhalate). Additionally suitable thermoplastic polymers include polyethylene, polypropylene (PP), polystyrene, polyvinylchloride (PVC), PVDC, and polyamides such as Nylon and particularly specific Nylon types such as polyamide 11, 12, 4/6, 6/6 and 6/10. Additionally suitable are thermoplastic elastomers such as elastomers of polyurethane, and

0141Hytrel™. Also contemplated are blends and alloys of the foregoing specific polymers.

0142Additionally, prefened are polyamide, polyolefin, polyetherimide (PEI), thermoplastic polyimide, polysulfone, polyurethane, copolyester copolymer, polypropylene (PP), polycarbonate (PC), copolyane elastomer (butylene, poly (alkylene ether) phthalate plus stabilizer) or a blend or an alloy thereof. Also suitable polymers for use with this invention include Texin™, (polyurethane (PU)), Udel (polysulfone (PSU)), Vectra A™ or Vectra B™ (liquid crystal polymer (LCP)), Ultem™ (polyetherimide), ethylene vinyl alcohol (EVOH); polypthalamide (PPA) (polypheylene sulfide (PPS) ); or a blend or an alloy thereof.

0143Additionaly suitable polymer materials suitable for use with this invention include those disclosed in U.S. Pat. Nos. 5,514,734, 5,747,560, and 5,866,645, the disclosures of which are incoφorated herein by reference.

0144A prefened polymer for many applications including those involving use in a manufactured article requiring a cushioning or gas bladder structure is Hytrel or a blend or alloy thereof. A prefened Hytrel is Hytrel 5526, Hytrel 5612, Hytrel 4056, Hytrel 5526, and Hytrel 5612; or a mixture thereof.

0145See also Kaplan, W. ed in Modern Plastics Encyclopedia (1999) (McGraw-

0146Hill Companies, NY) for more detailed information relating to the foregoing and other acceptable polymer materials for use with this invention.

0147In particular embodiments of this invention, the high temperature organic surfactant includes an onium salt preferably having the following general formula II:

0148<img file="WO0078540A1_D0001.tif" />

0149II wherein M is one of N, S, O or P atom, each of Rl, R2, R3 and R4 is independently an optionally substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloakyl, cycloalkenyl, cycloalkynyl, aryl, alkylaryl, alkenylaryl, alkynylaryl, alkylthio, alkylsulfinyl, alkylsulfonyl, or carboxycyclic aryl group; in which each of Rl, R2, R3 and R4 can be the same or different; and

0150X^" is defined as an acceptable counter ion.

0151Illustrative counter ions include those associated with clay minerals and may also include but are not limited to fluoride, chloride, bromide, iodide, acetate, carboxylate, ect.

0152As used herein, the term alkyl unless otherwise modified refers to both cyclic and noncyclic groups, although cyclic groups will comprise at least three carbon ring atoms. Alicyclic alkyl groups are generally prefened. Alkenyl and alkynyl groups of compounds of the invention have one or more unsaturated linkages, typically 1 to about 3 or 4 unsaturated linkages. Also, the terms alkenyl and alkynyl as used herein refer to both cyclic and noncyclic groups, although straight or branched noncyclic groups are generally more prefened. Alkoxy groups of compounds of the invention have one or more oxygen linkages, typically 1 to about 5 or 6 oxygen linkages. Alkylthio groups of compounds of the invention have one or more thioether linkages, typically 1 to about 5 or 6 thioether linkages. Alkylsulfinyl groups of compound of the invention have one or more sulfinyl (SO) linkages, typically 1 to about 5 or 6 sulfmyl linkages. Alkylsulfonyl groups of compounds of the invention have one or more sulfonyl (SO₂) linkages, typically 1 to about 5 or 6 sulfonyl linkages. Prefened alkylamino groups of compounds of the invention include those groups having one or more primary, secondary and/or tertiary amine groups, preferably 1 to about 3 or 4 amine groups. Suitable alkanoyl groups have one or more carbonyl groups, typically 1 to about 4 or 5 carbonyl groups. Alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkanoyl and other groups may be suitably either linear or branched. Carbocyclic aryl as used herein refers to non-hetero aromatic groups that have 1 to 3 separate or fused rings and 6 to about 18 carbon ring members and may include e.g. phenyl, naphthyl, biphenyl, acenaphthyl, phenanthracyl, and the like. Phenyl is often prefened. Suitable heteroaromatic or heteroaryl groups will have 1 to 3 rings, 3 to 8 ring members in each ring and from 1 to about 3 hetero atoms (N, O or S). Specifically suitable heteroaromatic or heteroaryl groups include e.g. courmarinyl, quinolinyl, pyridyl, pyrazinyl, pyrimdinyl, furyl, pynolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl, benzofuranyl, and benzothiazol.

0153As discussed above, many groups including alkyl groups are optionally substituted. Suitable groups that may be present on a "substituted" substituent include e.g. halogen such as fluoro, chloro, bromo and iodo; cyano; hydroxyl; nitro; azido; sulfhydryl; alkanoyl e.g. Cι-₆ alkanoyl group such as acetyl and the like; carboxamido; alkyl groups including those groups having 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms; alkenyl and alkynyl groups including groups having one or more unsaturated linkages and from 2 to about 12 carbon atoms, preferably from 2 to about 6 carbon atoms; alkoxy groups having one or more oxygen linkages and from 1 to about 12 carbon atoms, preferably 1 to about 6 carbon atoms; aryloxy such as phenoxy; alkylthio groups including those moieties having one or more thioether linkages and from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms; alkylsulfinyl groups including those moieties having one or more sulfinyl linkages and from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms; alkylsulfonyl groups including those moieties having one or more sulfonyl linkages and from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms; aminoalkyl groups such as groups having one or more N atoms and from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms; carbocyclic aryl having 6 or more carbons, particularly phenyl; aryloxy such as phenoxy; aralkyl having 1 to 3 separate or fused rings and from 6 to about 18 carbon ring atoms, with benzyl being a prefened group; aralkoxy having 1 to 3 separate or fused rings and from 6 to about 18 carbon ring atoms, with O-benzyl being a prefened group; or a heteroaromatic or heteroalicyclic group having 1 to 3 separate or fused rings with 3 to about 8 members per ring and one or more N, O or S atoms, e.g. coumarinyl, quinolinyl, pyridyl, pyrazinyl, pyrimidyl, furyl, pynolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl, benzofuranyl, benzothiazolyl, tetrahydrofuranyl, tetrahydropyranyl, piperidinyl, moφholino and pynolidinyl. A "substituted" substituent of a phosphonium compound of the invention may be substituted at one or more available positions, typically 1, 2 or 3 positions, by one or more suitable groups such as those listed immediately above.

0154By the term "salt" is meant that the subject molecule includes one or more ionic bonds. Exemplary salts are onium salts and such as sulfonium, phosphonium and ammonium salts disclosed herein.

0155In one embodiment of the invention, the inorganic layered silicate has the phosphonium salt represented above in Formula II preferably non-covalently bound thereto. In another embodiment, the invention provides a nanocomposite that includes at least one of the inorganic silicate compounds that have that phosphonium salt. A prefened phosphonium salt is the compound represented by Formula II in which M is P and each of Rl, R2, R3 and R4 is independently an octyl or phenyl group the same or different. In another embodiment of the silicate, each of Rl, R2 and R3 is a substituted or unsubstituted phenyl group and R4 is a substituted or unsubstituted alkyl group having between from about 16 to about 20 carbon atoms. In a particular embodiment, each of Rl, R2 and R3 is a butyl and R4 is a substituted or unsubstituted alkyl group having about 16 carbon atoms. In an additionally prefened embodiment, M is P and the P atom is fully substituted by substituted or unsubstituted phenyl groups, preferably unsubstituted.

0156In a prefened example of the invention, the inorganic silicate is montmorillanite which includes an underexchanged or overexchanged tetraphenyl phosphonium salt.

0157In addition to the foregoing ORMLAS, additionally prefened ORMLAS have a prefened d-spacing between layers of from between about 10 to about 60 Angstroms as determined by XRD, preferably from between about 10 to about 50 Angstroms. Typically, the XRD test is performed prior to contact with a desired polymer material. More prefened ORMLAS have a d-spacing of from between about 15 to about 30 Angstoms with about 18 to about 24 Angstroms being prefened for many applications. Additionally prefened ORMLAS are made from what is sometimes refened to as a "sol-gel" process. The ORMLAS themselves are preferably made from at least one metal alkyl silsesquioxane and especially an alumino-alkylsilsesquioxane. As discussed, the silsesquioxane can be readily modified to make product with desired performance characteristics including substituting the alkyl group with a non-aliphotic group, e.g., alkoxy and/or hydroxy. More prefened ORMLAS exhibit good high temperature stability.

0158See Example 1-2 below for more detailed disclosure relating to making and using ORMLAS.

0159Also prefened are ORMLAS of this invention that can be combined with one or a combination of suitable polymer materials including the particular polymers, polymer blends and polymer alloys referenced above. Of particular interest for many applications is a nanocomposite that includes at least one ORMLAS and optionally at least one of the inorganic layered silicates disclosed herein in which the silicate includes a Hytrel polymer intercalated therein. Alternatively, the Hytrel polymer is exfoliated in layers of the ORMLAS. As discussed, prefened Hytrel polymers include Hytrel 5526, Hytrel 5612, Hytrel 4056, Hytrel 5526, and Hytrel 5612.

0160Prefened use of the foregoing Hytrel nanocomposite includes use in the manufactured articles discussed herein including the claims below.

0161In embodiments in which the nanocomposite includes at least one ORMLAS, the amount of any particular ORMLAS in the matrix will generally follow the amounts already mentioned for the inorganic layered silicate unless otherwise stated. A prefened compatibilizing agent for use in the ORMLAS is an organo-silane including including molecular and polymeric agents suited for the intended use.

0162Additionally prefened nanocomposites exhibit good barrier properties as determined by recognized testing procedures and particularly standard solute transmission rate tests. See generally the American Society For Testing and Materials (ASTM) 1916 Race St. Philadelphia, PA 19103. See also U.S. Pat. No. 5,042,176 to Rudy; the disclosure of which is hereby incoφorated by reference. In one embodiment, the nanocomposite includes one ORMLAS or one inorganic layered silicate combined with a polymer material Hytrel, PET or polypropylene.

0163Additional transmission rate tests include those used in the field to measure gas transmission rates such as oxygen, nitrogen, carbon dioxide, water vapor, a noble gas; or a mixture thereof. Reference herein to a "standard water vapor transmission rate test" is meant that test described in ASTM publication D-3985-81 (Reapproved 1988) and entitled "Standard Test Method For Oxygen Gas Transmission Rate Through Plastic Film And Sheeting Using A Coulometric Sensor". Reference herein to a "standard oxygen gas transmission rate test" is meant that test described in ASTM publication F- 1249-90 and entitled "Standard Test Method For Water Vapor Transmission Rate Through Plastic Film And Sheeting Using A Modulated Infrared Sensor". See also the oxygen rate transmission system (modulator OX-TRAN^® 2/20) described by MOCOM^® (7500 Boone Avenue North, Minneapolis, MN 55428). Particular nanocomposites of this invention feature a gas or liquid transmission rate through the nanocomposite that is preferably at least about 1.5 fold lower than the neat polymer, preferably between from about 10 to about 200 fold less than the neat polymer as determined by the tests.

0164More particular "high gas barrier" nanocomposites are described in the discussions and examples which follow.

0165Additional nanocomposites in accord with this invention have been prepared by extrusion of synthetic ORMLAS clays and phosphonium exchanged clays with polyetherimide (PEI), nylon, and polycarbonate (PC). In general, there has been excellent dispersion of the ORMLAS within each of these polymers as shown by XRD and TEM. The phosphonium clays appear to intercalate. However, good exfoliation has not always been achieved. Both of these clays show excellent thermal stability for the temperatures required for the processing of these materials. Many of these nanocomposites have been subjected to DMA testing. These results display a higher modulus before and after the T_g of the materials. Those samples prepared for Nylon, despite no apparent improvement in T_g, show an improved use temperature due to an excellent enhancement in modulus.

0166As discussed, it is an object of this invention to provide novel ORMLAS which optionally include non-aliphatic chemical groups as part of the compatibilizing agent. Use of such agents in accord with the invention has been found to enhance several performance characteristics of resulting nanocomposites including improving synthesis and optimizing contact with polymer materials. More particular advantages of these compatibilzing agents include rendering the layered silicate somewhat more hydrophilic and enhancing intercalation and exfoliation. Prefened non-aliphatic groups include hydroxyl and alkoxy groups although other significantly hydrophilic groups can be used to suit an intended application.

0167Additionally prefened nanocomposites according to the invention are thermoplastic materials having good performance characteristics. Prefened nanocomposites are moldable into a variety of articles of manufacture, e.g., by conventional shaping processes, such as melt spinning, blow molding, casting, vacuum molding, sheet molding, injection molding and extruding. Examples of such molded articles are components for technical equipment, apparatus castings, household equipment, sports equipment including athletic footware and particularly sneakers, tennis shoes and the like, bottles, containers, components for the electrical and electronics industries, car components, circuits, fibers, semi-finished products which can be shaped by machining and the like. The use of the materials for coating articles by means of powder coating processes is also possible, as is their use as hot- melt adhesives. The molding compositions according to the invention are outstandingly suitable for specific applications of all types since their spectrum of properties can be modified in the desired direction in a plurality of ways.

0168Additionally prefened articles of manufacture will include or consist of these or other equally suitable nanocomposites of this invention. In one embodiment, the articles will have at least one of the following performance characteristics: 1) an impact resistance of at least about 10% better than the neat polymer; 2) a tensile modulus of at least about 10% better than the neat polymer; 3) a flame resistance of at least about 10% better than the neat polymer; 4) a glass transition temperature (T_g) of at least about 10% better than the neat polymer; 5) a melting temperature (T_m) of at least about 10% better than the neat polymer; and 6) a heat distortion of at least about 10% better than the neat polymer. Methods for determining these particular performance characteristics are known in the field and are referenced below. Of course, in embodiment in which the article includes a combination of polymer materials such as a blend or alloy, enhanced performanced will typically be referenced against the combined polymer material and not the neat polymer.

0169Prefened nanocomposites will have at least one of the foregoing performance characteristics when compared to neat polymer material.

0170The compositions of this invention including dispersed platelet particles are especially useful for fabrication of extruded films and film laminates, as for example, films for use in food and/or beverage packaging. Such films can be fabricated using conventional film extrusion techniques. The films are preferably formed to nearly any desired thickness, e.g., from about 10 to about 100 microns, more preferably from about 20 to about 100 microns and most preferably from about 25 to about 75 microns in thickness.

0171The nanocomposites of this inveniton can be formed by any suitable process for forming the composite. For example, nearly any nanocomposite of this invention can be conveniently prepared by blending processes of the type described in U.S. Pat. Nos. 4,739,007, 4,810,734, and 5,385,776; the disclosures of which are hereby incoφorated by reference.

0172In one embodiment of the blending processes described, a suitable monomer precursor of a desired polymer is polymerized following or contemporaneous with intercalation or exfolation. Suitable polymerization techniques include condensation polymerization, anionic polymerization, hydrolytic polymerization and the like. For example, in one such procedure montmorillonite intercalated with diaminobenzene is combined with phthalic anhydride in about a 1 : 1 molar ratio. The mixture is stired at about 160°C in NMP for about 16 hours to yield a polyimide. In this illustration of the invention, Platelet particles comprising one or a few layers of montmorillonite are dispersed through the polymer. A related technique can be practiced with the ORMLAS of this invention. Prefened composites, made with the ORMLAS, inorganic layered silicates, or mixtures thereof can be prepared by melt blending process in which the polymer precursor and the silcate are typically sheared in the melt at a temperature equal to or greater than the melting point of at least one of the polymer materials in the mixture until the particulate materials exfoliate and disperse to the desired extent.

0173Alternatively, solution polymerization techniques such as those disclosed in above and in Example 7 below may be more appropriate for making particular nanocomposites as discussed previously.

0174As a more specific illustration of an acceptable melt blend process, a suitable polymer material such as Nylon or Ultem is combined with a desired ORMLAS or inorganic layered silicate as provided herein. That mixture is heated to a temperature sufficient to form a polytherimide melt which is then sheared by a suitable means such as by standard shearing methods are employed by conventional extruder and injection molding implementations. Particularly good shearing action can be acheived by the polymer melt at one end of an extruder (single or double screw) and receiving the sheared polymer at the other end of the extruder. The temperature of the polymer melt, residence time of the melt in the extruder and the design of the extruder (single screw, twin screw, number of flights per unit length, channel depth, flight clearance, mixing zone etc.) are several variables which are known to impact the amount of shear to be applied.

0175In embodiments in which exfoliation is desired, the melt including the silicate composition and intercalated material may be subjected to shear mixing until the desired amount of material exfoliates to an acceptable extent. In general, at least about 80% by weight, preferably at least about 85% by weight, more preferably at least about 90% by weight and most preferably at least about 95% by weight of the material delaminate to form fibrils or platelet particles substantially homogeneously dispersed in the polymer matrix.

0176As will be appreciated by those in this field, any one or all of the aforementioned synthetic variables can be modified to suit an intended use of the silicate composition and particularly to enhance desired performance characteristics.

0177A silicate composition of this invention including the prefened nanocomposites already discussed may optionally include various components such as additives usually employed with particular polymer materials. These include optional components, e.g., nucleating agents, fillers, impact modifiers, chain extenders, plasticizers, colorants, uv stabilizers, thermal stabilizers, mold release lubricants, antistatic agents, pigments, fire retardants, and the like. Also included for some applications are conventional clay mineral swelling agents.

0178In a particular example of an acceptable melt blend process, the extruder used is a twin screw extruder preferably including standard conveying elements, kneading elements and mixing/dispersing elements. Preferably, the extruder is pre-heated to a temperature set of between about 99% to about 110% of the melting point of the neat polymer (or the blend or alloy thereof). In prefened production methods of the invention, there is output of blend (admixture) at a temperature of from between about 102% to about 110% of the melting point of the neat polymer (or the blend or alloy thereof). Starve feeding of the extruder is often prefened. Prefened operation of the twin screw extruder involves a maximum or near maximum pressure during kneading and conveyance stages. A prefened conveyance stage in the extruder is about 3 times longer in duration than the kneading time in the extruder. In this embodiment of the method for making the nanocomposites prefened output from the extruder is in the form of at least one of a rod, film, sheet, blow-molded, or extrusion blow-molded forms. Specifically prefened is a direct melt process discussed below in Examples 4 and 9 below.

0179The following discussion relates to several prefened aspects of the present invention including specific ORMLAS, inorganic layered silicates, nanocomposites and methods for making and using same. The discussion is meant to more particularly point out the invention. It is not intended nor should it be construed as being illustrative of the scope of this invention.

0180Referring to Figure IA, state-of-the-art compositions are schematically shown. Nanocomposites 1 have silicate layers 3 with alkyl ammonium surfactants 5 on the surface. The first part of the invention, schematically shown in Figure IB, provides new organic/inorganic nanocomposites structures 11 by substituting high temperature organic phosphonium cations 15 for the standard compatibilizing agent, viz., alkyl ammonium cations. In the new invention, ion exchange occurs with the more thermally stable organic phosphonium cations, e.g. tetraphenyl phosphonium 15 (Figure 2). That modification enhances the thermal stability of the nanocomposites from the cunent level of about 100-150°C to approximately 175-200°C or more without affecting other physical or mechanical properties of the resulting nanocomposites.

0181The inventors have synthesized a new class of phenyl phosphine-based arylene ether structural polymers that offer excellent mechanical and thermo-oxidative properties. Those polymers are somewhat similar in nature to phenyl phosphonium, are qualified for space missions by NASA and are being commercially produced.

0182As schematically shown in Figure IC, the invention also provides the innovative use of organically modified layered aluminosilicates 23 (ORMLAS) that combine the layered silicates and the organic compatibilizing agent 25 in a single chemical compound 21, rendering the material thermally stable, and highly organophilic. This dual function compound is then miscible with a host of structural matrix resins such as polyamides (nylon T_m 120°C), polyether imide (Ultem^® T_g 215°C), polyimides (T_g >275°C) and poly arylene ethers (T_g >225-350°C). These approaches offer processibility through both, solution techniques, as well as solvent- free direct melt intercalation technique. Moreover, since the bonding of the organic group to the inorganic Si atom is through the Si-C bonds, the ORMLAS exhibits excellent thermal stability. Fabricating ORMLAS layered silicates with high temperature structural polymers offers an attractive combination of properties such as high heat distortion temperature, excellent impact resistance and excellent mechanical properties.

0183The invention provides high use-temperature light-weight polymer/inorganic nanocomposites which have outstanding properties, compared to the state of the art layered silicate nanocomposites that use alkyl ammonium as the surfactant. A database of properties of control specimens is established for nanocomposites made from mixtures of a number of commodity polymers (e.g., Polystyrene Nylon, modified Polyetherimide, Polyethylene oxide) with montmorillonite containing alkyl ammonium-surfactants (through cation-exchange).

0184Superior polymer/layered silicate nanocomposites are fabricated by using mixtures of polyetherimide (PEI) resins with montmorillonite containing organic phosphonium surfactants, e.g., tetraphenyl phosphonium (TPP) (through cation- exchange), via direct polymer melt intercalation process.

0185Superior nanocomposites are fabricated by direct polymer melt intercalating organically-modified layered aluminosilicates (ORMLAS) with polyetherimide and thermoplastic polyimide (PI) or polyarylene ether (PAE) resins. The direct bonding of the organic surfactant group to the structural Si atom through an Si-C bond provides a "built in" surfactant with enhanced thermal stability, and also allows for easy tailoring of the organic-inorganic interface through the organic groups.

0186Interfacial, thermal, mechanical and physical properties of the fabricated nanocomposites are evaluated to optimize the most promising nanocomposites. The nanocomposites are designed by creating favorable interactions at the polymer-layered silicate interfaces. That is achieved by making the chemistry of the inorganic reinforcement phase more compatible with the organic polymer matrix, i.e., by making the layered silicate surfaces organophilic. The normally hydrophilic silicate surfaces are rendered organophilic after ion-exchange reactions of the loosely- held cations in the interlayer spaces of the silicate structure with organic cations.

0187Polymer-layered silicate nanocomposites have been synthesized for a variety of commodity polymer systems. Nanocomposites with properties much superior to that of the conesponding unfilled and conventionally-filled polymers are hence obtained. This unique combination of improved properties, easy fabricability, and low-cost, offers tremendous potential for commercial applications of these materials.

0188The synthetic creation of polymer/inorganic nanocomposites 31, schematically shown in Figure 3, exploits the ability of the layered inorganic silicates 23 to accommodate polymer 33 chains 35 between the layers 23 creating intercalated hybrids 37. Delaminated hybrids 39 are created by dispersing individual layers 23 in a continuous polymer matrix 41. Figure 3 shows a schematic representation 31 of the polymer/inorganic nanocomposite structures 37, 39 obtained using the layered silicates 23. Nanocomposites 37 have single polymer chains intercalated between the silicate layers 23. In nanocomposites 39 the host silicate layers 23 are delaminated and dispersed in a continuous polymer matrix 41.

0189That synthetic design also exploits the ion-exchange capacity of these layered- silicates 23 which allows for a fine-tuning of their surface chemistry to create a favorable organic-inorganic interface.

0190The advantages of the layered silicates in the synthesis of those nanocomposites arise from their unique crystal structure. Those layered silicate materials are fine-grained and have crystal structures with a "platy" habit. Their structure is common to the family of 2:1 layered- or phyllosilicates, well-known examples of which are mica and talc. The structure is composed of SiO4 tetrahedra fused to edge-shared octahedra of aluminum or magnesium hydroxides. Layer stacking leads to regular Van der Waals gaps between the layers, viz., interlayer or gallery. Isomoφhic substitution of cations is common (for example, A13+ or Fa3+ substituting for Si4+ in the tetrahedral network). That leads to a net negative charge on the structure, which is generally counter-balanced by cations residing in the interlayer spacing. Those cations are more or less readily exchanged and result in the cation-exchange capacity of the materials.

0191Those interlayer cations are, for example, Na+ or K+ in pristine layered silicates. For the synthesis of the polymer/inorganic nanocomposites, an organophilic surface chemistry is desired to create favorable interactions with the organic polymer matrix. Therefore, those inorganic cations are exchanged with various organic cations, e.g., alkyl ammonium cations. The hydrophilic silicate surface is thus rendered organophilic. Those surfactants typically are alkyl ammonium compounds e.g., dimethyl ditallow ammonium bromide. One example is the use of dimethyl ditallow ammonium bromide to cation-exchange with the Na+-montmorillonite - a layered silicate. Such ion-exchanged 'organo' silicate clays are commercially available. Herein lies the opportunity to tailor the interfacial chemistry of those polymer/inorganic nanocomposites through creation of the organic functional groups. The properties of the nanocomposites can be optimized through interfacial surface chemical design.

0192The synthesis of layered silicate nanocomposites has involved intercalation of a suitable monomer followed by in situ polymerization including the melt processes discussed generally above. Alternatively, polymer intercalation is carried out from solution. These techniques limit use in the case of most technologically important polymers, since suitable monomers and compatible polymer-silicate solvent systems are not always available. The spectrum of nanocomposite systems that can be synthesized is considerably broadened by the advent of a more versatile and environmentally-friendly synthetic approach, called direct polymer melt intercalation. In that approach, the polymer and the silicate are mixed, and the mixture is heated above the softening point of the polymer. That technique allows the synthesis of a much wider range of polymer/inorganic nanocomposites. Polymers with varying degrees of polarity and crystallinity are directly intercalated into organically-modified layered silicates. Example of polymers use direct polymer melt intercalation include polystyrene, poly(dimethylsiloxane), poly(vinylidene fluoride), poly (e-caprolactone), and (polyethylene oxide).

0193Delamination of the silicate layers can also be achieved during nanocomposite synthesis through 'polymer melt intercalation'. An example is the delamination of the individual silicate layers achieved by suspending ditallow ammonium-exchanged montmorillonite in PDMS (Polydimethylsiloxane) at room temperature and sonicating for 2 minutes.

0194The nanocomposites provided by this invention can be compared to those nanocomposites shown in Figure 4. This figure was obtained from Giannelis, E.P. (1996) Adv. Materials 8:29-35. See also Kurauchi, T. et al., (1991) SAE Technical Paper Series, 910584. As shown in Figure 4, several Nylon-6 properties are enhanced when the polymer is in nanocomposite form. Similar enhancements were observed for many polymer materials when used to make the nanocomposites provided herein.

0195In particular, Figure 4 shows that for Nylon-6 the tensile strength and modulus are enhanced without significant loss in impact strength. Loss of impact strength is usually witnessed with such enhancements in the case of conventional filled polymers. The significant increase in the heat distortion temperature (i.e., 145°C up from 65°C) extends the use-temperature of Nylon to under-the-hood structural components in automobiles. A reduction in water adsoφtion accompanies the improvements in mechanical properties. These and other features were seen with the nancomposites of this invention.

0196Considerable increases in heat resistance and thermal stability are obtained with these nanocomposites. Polydimethylsiloxane-layered silicate nanocomposites have a delayed thermal decomposition compared to that of the pure polymer - which decomposes into volatile cyclic oligomers. The improved barrier properties of these nanocomposite materials are demonstrated through measurements of relative permeability of liquids and gases through the nanocomposites. Dramatic reductions in permeability are obtained at low inorganic contents compared to conventionally- filled polymers with much higher filler contents. The large aspect ratio of the silicate layers forces the solutes to follow more tortuous paths in the polymer matrix around the silicate layers. That results in much larger effective diffusion distances, and hence lower permeabilities. The enhanced thermal stability of the nanocomposites is also attributed to the hindered out-diffusion of the volatile decomposition products. Self- extinguishing characteristics in those materials are related to the barrier properties rendered by the silicate layers.

0197A key to obtaining superior properties at low inorganic loadings is the homogeneous nanoscale dispersion of the inorganic phase in the polymer, and the creation of favorable interactions at the organic-inorganic interface. Favorable interfacial chemistry leads to organic and inorganic phases being dispersed at a nanometer level. The superior properties of the new composites are obtained at low inorganic loadings. The use of low inorganic contents leads to significant advantages. High degrees of stiffness, strength and barrier properties are obtained with far less inorganic content than comparable glass- or mineral reinforced polymers. Considerable weight savings are, therefore, obtained.

0198Some commercial applications of these materials are, for example, Nylon- layered nanocomposite automatic timing belt cover. Other applications include aiφlane interiors, fuel tanks, components in electrical and electronic parts, under-the- hood automotive structural parts, brakes and tires. Applications of nanocomposite barrier films may be used in food packaging and in other applications are also possibilities.

0199The fact that the nanocomposites yield significant enhancements in properties at low inorganic loadings also provides ease-of-manufacturing and several cost- benefits. It allows for the use of simple manufacturing techniques (viz., extrusion, injection-molding and casting) which are normally used for pure polymers. Therefore, the nanocomposites can be manufactured at a much lower cost than the more conventional fiber- or mineral-reinforced composites which require more expensive fabrication procedures. That provides further reasons for their commercial appeal.

0200Commodity polymers provide use-temperatures below 125°C. Substructure applications for rockets and aircrafts require higher long term use-temperatures of about 175°C and 250°C.

0201The thermal stability of the cunent state-of-the-art nanocomposite systems is often limited by the thermal instability of the surfactants used to create favorable interactions at the interface. Those surfactants typically are alkyl ammonium compounds. One example is the use of dimethyl ditallow ammonium bromide to ion- exchange with the Na+-montmorillonite - a layered clay. The thermal stability of the nanocomposite system is therefore, limited by the thermal stability of the alkyl ammonium compound. Degradation of those surfactant molecules, and hence that of the organic-inorganic interface, begins at temperatures around 100-110°C.

0202The invention provides more thermally stable surfactants, which optimize the dispersion of the inorganic phase, and also enhance the compatibility at the organic- inorganic interface through the creation of favorable interactions. The invention therefore provides enhanced use-temperatures of the nanocomposites. One part elevates the use-temperature of the nanocomposite system by using more thermally stable surfactants than the cunently used alkyl ammonium compounds.

0203The first part provides tetra-phenyl phosphonium compounds (with thermal stability in the range of 190-200°C) to carry out a cation-exchange with the layered silicate reinforcement. Tetraphenyl phosphonium is a reactive salt with a net positive charge, as shown in Fig. 2. The salt readily ion exchanges with the cation on the surface of the inorganic phase attaching itself from the oxide surface and thus rendering the surface organophilic. That surface modified system lends itself to direct melt intercalation. Because tetraphenyl phosphonium is a high temperature organic moiety with thermal stability in excess of 200°C, the first part of the invention provides nanocomposites which will satisfy the need for long-term use-temperatures of l75°C-200°C.

0204The second part of the invention extends the use-temperature of the nanocomposites to over 250°C. It is based on the innovative use of organically- modified layered alumino-silicates (ORMLAS) that combine the layered silicate and the organic surfactant/compatibility agent in a single chemical compound. The organic surfactant groups are bonded to the structural Si atom through thermally stable Si-C bonds. The thermal stability of the overall system is therefore greatly enhanced. Therefore, those materials provide unique inorganic layered silicate reinforcements having markedly more thermally-stable surfactants "built-in" to the chemical structure. Those materials are miscible in a host of structural matrix resins, such as polyamides (nylon Tm 120°C) and polyether imide (Ultem T_g 215°C), polyimides (T_g > 275°C) and poly arylene ether (PAE T_m > 325-350°C).

0205Those ORMLAS materials are synthesized using the sol-gel process where the organic groups are incoφorated into the molecular structure through the use of organically modified silicon alkoxides, i.e., precursors containing Si-CxHx bonds. The organic functionality is therefore directly bonded to the structural Si atom by the Si-C bond. The organically modified aluminosihcate will be synthesized using mixtures of organically-modified silicon alkoxides and solutions of aluminum chloride. The standard approach combines an alcohol solution of aluminum chloride with an alcohol solution of organically functionalized alkoxysilane. The organically functionalized trialkoxysilane, e.g., alkyltriethoxysilane, provides alkyl organic groups connected directly through Si-C bonds. The mixture is then condensed (crosslinked) to form a gel at appropriate pH conditions by the addition of NaOH. The gel is aged, filtered, washed with distilled water, and then dried in vacuum. That procedure yields a stable layered organophilic compound. The resulting material is either precipitated as a powder, dried and ground to appropriate particle size, or case into various shapes and forms. In that cast, the ORMLAS is precipitated as a powder or ground and classified it into appropriate size particles for incoφoration with the polymer matrix for direct melt intercalation. A unique feature of those ORMLAS compounds is that they are especially engineered to delaminate in the presence of a variety of polymer resins - thus promoting the dispersion of the inorganic layers in the polymer matrix. That versatile and innovative new feature yield nanocomposites which will satisfy needs for a range of use-temperatures extending to long-term use- temperatures over 250°C.

0206In addition to the enhanced thermal stability, the use of synthetic organically- modified layered silicates (ORMLAS) having built-in surfactants eliminates the poisonous alkyl ammonium surfactants which limit the applications of nanocomposites as food packaging materials. The elimination of the ion-exchange also lowers the processing costs. Therefore, that technique yields recyclable and more cost-effective food packaging materials with superior gas-barrier properties to replace unrecyclable multilayer plastic food packaging materials.

0207The following examples and discussion address particularly prefened embodiments of the chemical optimization of ORMLAS materials, the optimization of phosphonium exchanged natural clays, the extrusion fabrication of Ultem- nanocomposites using the layered silicates with higher thermal stability, and the analysis of the nanocomposite properties. In particular, the following describe the synthesis of long chain phosphonium exchanged natural clays. A discussion of the fabrication of a variety of nanocomposites using polymers such as Ultem, and Nylon is additionally provided. As also disclosed below in the examples, the silicate compositions of this invention including the nanocomposites can be characterized by one or a combination of different stategies such as Differential Scanning Calorimetry (DSC), Transmission Electron Microscopy (TEM), Dynamic Mechanical Analysis (DMA), Heat Distortion Temperature (HDT). These and other material characteristics can be detected and quantified if desired using conventional tests well known in the field. See, e.g., the ASTM. Unless specifically mentioned otherwise, the phrase "heat distortion temperature" or related term or phrase is meant thermo-mechanical analysis used to determine how the presence of a particular nanophase inorganic affects the heat distortion temperature of the suject. new material. Prefened is the standard test performed by SGS US Testing Company Inc. (F airfield, NJ).

0208By the phrase "dynamic mechanical analysis" or related term or phrase is meant a dynamic measurement of the modulus with respect to temperature. As will be understood, this property is an important gauge of the actual use temperature of the material and it provides a measure of the enhancements in use-temperatures of the polymers, e.g., a result of the nanoscale distribution of the inorganic phase.

0209By the phrase "thermal stability" or related term or phrase is meant stability detectable by differential scanning calorimetry (DSC) and particularly the change in the glass transition temperature of the matrix polymer as well as thermal performance of the resulting nanocomposites.

0210By the phrase "interfacial characterization" or related term or phrase is meant interface characterization as determed by Transmission Electron Microscopy (TEM). The present disclosure provides many examples of the layered structure of the

0211ORMLAS materials as well as the nanoscale dispersion of the inorganic layers within selected polymer materials. Interfacial properties are often critical for long term rise of the nanocomposites.

0212By the phrase "tensile properties" or related term or phrase is meant tensile strength, tensile modulus and elongation to break for each polymer system as assessed in accordance with ASTM standards. Prefened is Instron testing.

0213By the phrase "impact resistance" or related term or phrase is meant ASTM standard for impact resistance and particularly to assess the nanocomposite mpact strength. Nanocomposite pellets will be used to mold appropriate articles to accommodate this testing. By the term "dispersion of inorganic phase" is meant wide angle x-ray diffraction (WAXD) pattern of the nanocomposite to generate data to evaluate evaluate the orientation of the inorganic phase within the polymer matrix. This disclosure provides powder XRD patterns to obtain information about the extent of dispersion of the silicate layers in the polymer.

0214"Layered material" shall mean an inorganic material, such as a smectite clay mineral, that is in the form of a plurality of adjacent, bound layers and has a thickness, for each layer, as specified herein.

0215"Platelets" shall mean individual layers of the layered material.

0216"Intercalate" or "Intercalated" shall mean a layered material that includes polymer material disposed between adjacent platelets of the layered material. In most instances, the word "intercalate" or "intercalated" shall also mean an increase in interlayer spacing between the adjacent platelets by at least about 2 A.

0217"Intercalation" shall mean a process for forming an intercalate.

0218"Intercalant polymer" or "intercalant" shall mean an oligomer or polymer that is sorbed between platelets of the layered material and complexes with the platelet surfaces to form an intercalate.

0219"Intercalating carrier" shall mean a canier comprising water with or without an organic solvent used together with an intercalant polymer to form an Intercalating Composition capable of achieving Intercalation of the layered material.

0220"Intercalating pomposition" shall mean a composition comprising an intercalant polymer, an intercalating carrier for the intercalant polymer, and a layered material. "Exfoliate" or "exfoliated" shall mean individual platelets of an intercalated layered material so that adjacent platelets of the intercalated layered material can be dispersed individually throughout a matrix polymer; or throughout a carrier material, such as water, an alcohol or glycol, or any other organic solvent.

0221"Exfoliation" shall mean a process for forming an exfoliate from an intercalate.

0222"Nanocomposite" shall mean an oligomer, polymer or copolymer having dispersed therein a plurality of individual platelets obtained from an exfoliated, intercalated layered material.

0223"Matrix polymer" shall mean a thermoplastic or thermosetting polymer in which the Intercalate and/or exfoliate is dispersed to form a nanocomposite.

0224As discussed, the invention features nanocomposites that have good barrier properties particularly to at least one solute such as a gas or liquid. Preferably, the nanocomposites exhibit a significant barrier to gas such as water vapor.

0225U.S. Provisional Application U.S.S.N 60/139,481 entitled "Nanomaterials for

0226Banier Applications" and filed on June 17, 1999 provides a variety of nanocomposites and methods for making same; the disclosure of which is hereby incoφorated by reference.

0227In particular, the U.S.S.N 60/139,481 application discloses layered organo alumino silicate fillers and methodology for producing a varietey of layered alumino-silicate nanomaterial filled polymers. Prefened methods include thermoplastic processing techniques to produce high performance nanocomposite layer silicate-filled thermoplastic polymers. The approach is based on the use of layered silicates with organo functional groups examples of which are described herein. Also provided are alkyl ammonium montmorillonite layered aluminosilicates as additives to a host of polymer materials and particularly thermoplastic polymers. Examples of polymers include polyolefins, polyesters, copolyesters, polyurethane and polyurethane copolyester copolymers. Prefened organofunctionalized silicates contain organic contents varying from 20 percent up to 65 percent by weight. The organosilicates can be added in quantities less than 1 percent up to 22 percent by weight.

0228A prefened method of processing the nanocomposites disclosed in the U.S.S.N 60/139,481 provisional application is by thermoplastic compounding. Single or twin screw extruders are used as the prefened processing equipment. The nanocomposite organosilicate additive can be incoφorated simultaneously with the polymer matrix by premixing the filler powder with polymer pellets, granules or powder.

0229The polymer/nanocomposite material preferably is produced by first introducing the polymer resin into an extruder. Applying heat melts the polymer. The layered silicate additive is introduced to the molten polymer, by the same or a separate port. The two-step process enhances the mixing action associated with nanocomposite and leads to better performing nanocomposites. In this invention nanocomposites and nanomaterials refers to the resultant polymer combined with the layered organoaluminosilicates (nanocomposite fillers) which provide enhanced barrier qualities.

0230As discussed in the U.S.S.N 60/139,481 provisional application, nanocomposites produced using alkyl ammonium montmorillonite layered aluminosilicates with Hytrel 5526 or Hytrel 5612 at contents varying from 5% up to 12.5%, and preferably about 7.5%, by weight of the layered aluminosilicates. The extruded products resulted in excellent resistance to gas permeation as well as unexpected enhancement in mechanical and physical properties. Hytrel is a du Pont trademark that refers to particular thermoplastic extrudable and blow moldable low modulus of elasticity polyester elastomer resin. Hytrel is a butylene/poly (alkylene ether) phthalate plus stabilizer. The first two numbers refer to hardness on the Rockwell hardness R scale. The third number refers to inherent viscosity and flowability. The last number refers to the type of antioxidant contained.

0231Blow molding experiments have demonstrated the blow moldability of Hytrel 4056, 5526 and 5612 nanocomposites. However, the work has also pointed out difficulty in cutting the extrudate using a "hot-knife." The problem appears to relate to the extrudate sticking to the knife. This problem has not been noticed with neat Hytrel 5612 resin. The selection of 5526 grade was based on its excellent impact resistance and low melt flow viscosity, compared to 5612. The addition of layered silicates to 5612 makes it easier to process that thick grade of Hytrel. Hytrel 5612 is a blow molding grade that has been successfully blow molded. Hytrel 5556 is a high impact strength grade with flow viscosity between the 5612 and 5526 grades.

0232As disclosed in the U.S.S.N. 60/139,481 provisional application, all three grades of Hytrel are compounded with layered silicates to carry out blow molding experiments. A prefened compounding method is provided as follows.

0233The components are combined by adding the powder into the molten material and mixing and shearing in a screw extruder, using a high screw φm (above about 130 and preferably about 150 to 167 or up to about 1000 φm) to decrease residence time, increase yield, and conserve energy. All of these parameters are of interest.

0234The new layered silicate nanocomposite elastomeric compounds are effective barrier materials.

0235The invention disclosed in the U.S.S.N 60/139,481 provisional application provides new nanotechnology and is well-suited for a wide spectrum of uses including use as a gas encapsulation medium. In particular, the invention is focused on identifying suitable elastomeric resins that are reinforced with nanolayered aluminosihcate inorganic materials at loading levels from below about 5 percent by volume to above about 22% by volume. Emphasis is placed on defining the optimum inorganic reinforcement that maximizes the barrier properties of the base resin with minimum adverse effect on the processability, toughness and fatigue properties of the resin.

0236Having identified the most suitable organic/inorganic nanostructures, the invention further involves fabrication and demonstration of uses of the most successful nanostructure systems and prototype pouches.

0237In particular embodiments of the invention disclosed in the U.S.S.N. 60/139,481 provisional application, three matrix resins are reinforced at 5% by volume with two specialty nanolayered aluminosilicates each. The matrix resins are three.

0238(1) Polyurethane, the cunent material used in pouches, is used as a baseline material.

0239(2) Hytrel 4056 is a du Pont low modulus, extrusion grade thermoplastic polyester elastomer resin with wide industrial usage.

0240Hytrel is a butylene/poly (alkylene ether) phthalate plus stabilizer.

0241(3) Hytrel/PET Blend is partially crystalline thermoplastic elastomeric compound that combines processability with enhanced barrier properties used as a component in blends. PET is polyethylene terephthalate to which may be added fillers, and which may be modified with other additives such as plasticizers, lubricants, antioxidants and pigments.

0242The Hytrel 5526 is in granular or powder form. The other Hytrel materials are pellets. All are dried before melting. The nanocomposite fillers are fine granular powders that do not require drying. After drying the base components Hytrel or Hytrel/PET blend are melted at above 235°C and above 255°C, respectively, and are sheared in a screw conveyor. The melt temperature is maintained, and the nanocomposite additive powder is added. Shearing and mixing continue. Applied heat may be dropped as the shearing continues the input of heat to maintain the melt temperature. The materials are thoroughly mixed before being forced through a film extrusion die. Layered aluminosihcate reinforcements offer maximum compatibility with the resins of choice and minimize departure from standard processing conditions of the neat resins. The table shown immediately below presents a test matrix.

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0244Proposed Experimental Matrix

0245Polyurethane Hytrel 4056 Hytrel PET

0246Blend

0247Neat Resin Systems O Vol% O Vol% O Vol%

0248Layered 5 Vol% 5 Vol% 5 Vol%

0249Aluminosihcate A

0250Layered 5 Vol% 5 Vol% 5 Vol%

0251Aluminosihcate B

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0253Other runs were performed using Hytrel 5526 and 5612 with loadings of about 5%, 10% and 7.5% by weight nanocomposite aluminosilicates A and then B.

0254Neat and nano-reinforced resin systems are used in a thermoplastic extrusion process to produce ASTM compliant flat 2.0 in x 2.0 in specimens at from about 0.030 to about 0.060 (0.75 to 1.5 mm) in thickness. Duplicate gas transmission rate information for helium and nitrogen are generated. The performance of the resulting nanocomposite structures are compared with that of polyurethane pressurized pouch cunently used in footwear applications. Nanocomposite specimens and the gas transmission test results show improved performance over the basic resins.

0255The nanocomposite system(s) identified above are scaled up and blow molded into pouches. These pouches are inflated with gaseous form of helium with a secondary nitrogen gas.

0256The resulting pouches undergo evaluation including barrier, life cycle fatigue, puncture resistance and crazing.

0257Hytrel is a blow moldable composition. The first two numbers in the designations designate hardness, and the third number designates flowability, the lower numbers having higher viscosity and lower flowability. Most of the Hytrel compositions are supplied in pellets. Preferably before molding the Hytrel is dried overnight (about 8 hours) at about 71°C. Before molding the Hytrel is dried at about 99°C for about 3 hours. The layered aluminosilicates need no drying. They may be added to the Hytrel during the drying, when they are mixed with the Hytrel before melting. However, it is preferable to melt and shear the Hytrel and then add the layered nanocomposite fillers. The Hytrel has a melting point of about 170°C to about 220°C (about 338°F to about 428°F). There are no volatiles and no gases to be removed upon melting. The PET in the Hytrel/PET blend enhances the entire blend with the increased strength of PET and has a melting point of about 250°C to 255°C (about 482°F to 491°F). The PET has a slightly higher specific gravity, about 1.55 to about 1.81, than the Hytrel, about 1.14 to about 1.27.

0258Anti-sticking additives in the form of antioxidants or antiblocking agents, such as Kemamide B (Humko Sheffield Chemical Division, P.O. Box 398, Memphis, TN, USA) and Crodamide SR (Croda Universal Limited, North Humberside, DN14 9 A A, England), may be added if desired.

0259The U.S.S.N 60/139,481 provisional application discloses particular methods of making nanocomposites having Hytrel or Hytrel/PET blends.

0260For example, granular or pelletized thermo polymer is melted in a first stage of a twin screw extruder, where the temperature is kept above the melting point of the Hytrel or Hytrel/PET blend. When the Hytrel is molten and is sheared by the screw flights, the nanocomposite powders are added. That may be up to about halfway through the screw extruder. Pitches and diameters are increased and varied following the addition of the nanocomposite additives to thoroughly mix and shear the components, while the temperatures within the components are held above the melting temperatures.

0261Preferably 1000 φm speeds are maintained on drive motors. The extruder screw gear ratio may be about 6:1 or 3:1. Therefore actual screw speed at 1000 φm may be about 167 φm or 333 φm. Temperatures are maintained throughout the screw conveyor to about 235°C in the case of Hytrel, and about 265 °C in the case of the Hytrel/PET blend, to sustain a high throughput. Applied temperatures in latter zones are adjusted slightly downwardly, as screw pitches and shear changes keep melt temperatures above the desired levels.

0262In examples, Hytrel is fed to screw extruders at rates of from about 65 to about 113 kilograms per hour. Nanocomposite fillers are fed from about 7 to about 13 kilograms per hour. Total feed rates are about 75 to about 125 kilograms per hour. Dwell time in the screw extruder is about 6 to 10 minutes. Extruders used in the examples had a one inch size with a length diameter ratio of 24:1, and were used without event. A three horsepower motor drove the extruders. The extruders had a breaker plate and screens of 40 mesh and were operated at a pressure of about 450 psi. The melt was cooled to about the melt temperature at extrusion. Automatic air cooling followed by water cooling of the extruded sheets was used. Screws had thread depths of from about 0.180 inches to about 0.060 inches. In one example, extruders had eight feed flights, eight transition flights and eight metering flights. The material was extruded through an eight inch sheet die at a 30 mil thickness. The material was collected on a three-roll sheet stack and winder and was auxiliary water cooled. The thickness of the sheet may be varied from about 30 mils to about 60 mils, and the width of the sheet may be about 6 to 8 or 7.75 inches.

0263The prefened organoaluminosilicate powder additives are polymer/inorganic nanocomposite materials with enhanced thermal stability and performance characteristics developed by Triton Systems. Two techniques enhance the thermal stability of the nanocomposite systems to over 250 °C. The two unique approaches are based on innovative chemical design of the organic-inorganic interface using (i) more thermally stable surfactants/compatibility agents, and (ii) more thermally stable synthetic organically-modified layered-silicate reinforcements to create unique nanocomposites. These approaches offer processibility through both solution techniques, as well as solvent-free direct melt intercalation technique.

0264Synthetic organically-modified layered silicates having built-in surfactants are used, as well as alkyl ammonium surfactants.

0265The properties of these nanocomposites are optimized in order to manufacture these materials in commercially applicable forms, e.g. films, fibers and molded components. The new technology provides hitherto unobtainable thermal stability and performance characteristics, and has numerous applications in automotive, aerospace, electronic and food and beverage industries. Reference herein to "high gas-barrier" nanocomposite or a related term is meant that the nanocomposite is capable of retarding the transmission rate of a gas solute through a nanocomposite (or blend thereof) by at least about 1.5 fold lower than the neat polymer, preferably between from about 10 to about 200 fold lower than the neat polymer as determined by standard tests described previously including the oxygen and water vapor transmission rate tests.

0266In some embodiments, it will be helpful to express reduced diffusion of solute through a particular nanocomposite in terms of transmission rate of a gas such as air, oxygen, water vapor or a noble gas, e.g., helium. Examples of such high gas-barrier nanocomposites include those in which Hytrel, PET or polypropylene or a blend or alloy thereof; is the prefened polymer material. More prefened are nanocomposites formulated into a manufactured article such as a cushioning or gas bladder structure and exhibiting a helium transmission rate of less than about 20 x 10^" cm.cm³/sec.cm².atm.

0267Additionally prefened high-gas barrier nanocomposites in accord with this invention are made from at least one suitable layered silicate material and at least one suitable polymer material as printed herein. In many instances, a desired high gas- barrier nanocomposite will include one layered silicate and one suitable polymer although other combinations may be more suited for specific applications. In a particular embodiment, the nanocomposite will include between from about 0.5% to about 10% by weight of the layered silicate, preferably about 1% to about 8% of the layered silicate, with about 5% by weight being prefened for many applications.

0268Illustrative layered silicates and polymer materials for making the high gas- barrier nanocomposites include those which can be readily compounded at about 250°C. Prefened conesponding strategies include using recognized "in line" thermoforming steps. Prefened layered silicates include naturally occurring Na⁺- Montmorillonite ion-exchanged with (i) Dimethyl hydrogenated-tallow (2-ethyl hexyl) ammonium compounds, and (ii) Methyl tallow bis2-hydroxyethyl ammonium compounds. Methods for conducting the ion-exchange are provided below. Prefened polymer materials include PET, polyolefin, EVOH, as well as other suitable materials.

0269As discussed in the following Examples, one method of making the high gas- barrier nanocomposites involves positioning at least one and usually a plurality of high aspect ratio silicate layers within a selected polymer material including blends or alloys thereof. A particular high gas-barrier nancomposite is shown schematically in Figure 23.

0270The high gas-barrier nanocomposite shown in Figure 23 can be made by one or a combination synthetic routes. Particular routes generally achieve good nano- dispersion of silicate layers within the polymer material. A more particular synthetic route involves optimizing silicate platelet dispersal within the polymer matrix on or about a nanometer scale.

0271The high-gas barier nanocomposites of this invention preferably include silicate layers with high aspect ratios. This feature of the invention provides several advantages. For example, the large aspect ratio typically forces gaseous solutes such as air, oxygen or water vapor, to follow more tortuous paths within the polymer matrix and around the silicate layers when compared to a neat polymer control. The resulting high gas-barrier nanocomposite possesses a larger effective diffusion distance and lower solute permeability when compared to conventional nanocomposites. The anow in Figure 23 exemplifies the lowered solute permeability. Also, the nanocomposites usually require small amounts of the layered silicate phase (e.g, about 5% by wt) to achieve good high gas-barrier properties. This characteristic of the invention provides several particular benefits including reducing the amount of precursor needed to make the nanocomposites and facilitating processing steps, e.g., by improving contact between the silicate layers and excess polymer material.

0272In contrast to the high gas-barrier nanocomposites of this invention, conventional filled-polymers generally require much more of the silicate phase. Accordingly, those polymers cannot easily provide the advantages offered by these nanocomposites.

0273As discussed, the invention encompasses a wide spectrum of manufactured articles. One such article is adapted to hold one or more compositions such as a pharmaceutical or drug composition. Prefened are those compositions having a solid dosage form, e.g., pill, tablet, capsule and the like. An illustrative use of the article is in combination with at least one sheet or strip assembly such as those routinely used to retain pharmaceuticals for storage, shipping and the like. More particular assemblies include foil and/or paper based assemblies that can be adapted in sealing disposition with the article. In this embodiment of the invention, the combination of the article and the sheet or strip assembly will often refened to as a "blister" or "bubble" pack or related phrase.

0274In another embodiment, the article can be adapted to essentially completely hold the composition without combination with the sheet or strip assembly. This example of the invention has many applications including use in situations where long-term or highly protected storage of the composition is desirable.

0275The invention contemplates a wide variety of more specific articles including the blister pack. In one embodiment, the article is formulated to include at least one of the disclosed nanocomposites which nanocomposite will preferably includes at least one of the polymer materials disclosed herein. In this embodiment, the nanocomposite will include at least one of the inorganic layered silicates provided herein (e.g., ORMLAS) and at least one of the disclosed polymer materials. Choice of a particular nanocomposite (or blend thereof) for use with the article will be guided by understood parameters such the performance characteristics needed for a particular application including strength and impact resistance. In many instances, the high barrier properties of the articles will be of specific interest.

0276In particular, in embodiments in which the article is intended for use as the blister pack, articles exhibiting high barrier properties will often be prefened. Choice of a particular nanocomposite (or blend of nanocomposites) for making the article will be guided by pre-determined capacity of the nanocomposite to exclude at least one solute such as gas (e.g., air, oxygen or water vapor). Prefened capacity will positively impact the usefulness of the article e.g., by enhancing the shelflife and or storage characteristics of the composition to be held and protected by the article.

0277In a more specific embodiment, the article will include and usually consist of a nanocomposite that features a gas transmission rate that is preferably at least about 1.5 fold less than the neat polymer, preferably at between from about 10 to about 200 fold less than the neat polymer and as determined by standard transmission rate tests. Specifically prefened tests include those formatted to measure oxygen and water vapor transmission rates through the nanocomposite (or article) as discussed previously.

0278As discussed, the invention also features polyolefin-layered silicate polymer nanocomposite materials. In one embodiment, the materials include polyolefin, comprising between from about 40 to about 99% by weight of nanocomposite; polyamide, comprising between from about 1 to 55% by weight of polyolefin; what is refened to herein as "functionalized grafted polyolefin" comprising between from about 0.5 to about 25% by weight of polyamide polymer; organoclay, comprising between from about 1 to about 40% by weight of the polyolefin; and, optionally, synthetically formulated organoclay formed by self-assembly techniques, comprising between from about 0 to about 25% by weight of the polyolefin.

0279The foregoing polyolefin-layered silicate polymer nanocomposite materials can be made from a variety of specific components.

0280For example, in one embodiment, the polyolefin is polypropylene or polyethylene. A particular polyamide is Nylon 6, Nylon 66 or Nylon 12 and a particular functionalized grafted polyolefms is a homo- or copolymer of polyolefin with maleic anhydride and/or methacrylic acid grafting functionality, or maleic anhydrite and or epoxy grafting functionality. In addition, the polyolefin-layered silicate polymer nanocomposite materials can be made from one or a combination of clay minerals. As an illustration, a prefened organoclay is 2:1 layer phyllosilicate (smectite), or mixed layer silicates (smectite-illite, smectitechlorite, smectite-kaolinite) where exchangeable interlayer cations (K, Ca, Mg, Na, Li, Cu. Al) are completely or partially substituted by organocations, including but not limited to functionalized or non-functionalized alkyl (C₈ to C₂₄) - ammonium ions [from C₈Hι₇H₃N⁺ to C₂₄H₄₉N⁺ ] or alkyl (C₈- C₂₄) -trimethylammonium ions [from C₈Hι₇N⁺(CH )₃ to C ₄H₄₉N⁺(CH₃)₃] or aliphatic amino acids [from C₈H]₇COOH to C₂₄H ₉COOH]. If desired, interlayer organocations may contain alkylene (alkyl-phenyl) groups. Preferably, the periodicity of organoclay is from 1.8 to 10 nm in order to provide intercalation of polymers in interlayer spaces of the organo-layered silicates and/or delamination of individual layers of the silicate particles with further exfoliation of those layers within polymer or polymer blend matrix during processing.

0281Prefened synthetically-designed organo-clays are organically-modified layered alumino-silicates that combine the layered silicate and the organic surfactant and the organic surfactant in a single chemical compound. The organic surfactant groups are bonded to the structural Si atoms through Si-C bonds. These materials provide unique inorganic layered silicate reinforcements with stable organic surfactants "built-in" to the chemical structure. A unique feature of these compounds is that they are especially engineered to delaminate in the presence of a variety of polymer resins including polyolefms and polyamides, and therefore display excellent dispersion of the individual layers in the polymer matrix.

0282The polyolefin-layered silicate polymer nanocomposite materials of this invention (sometimes refened to as "polymer alloy nancomposites") provide important advantages.

0283For example, in embodiments in which the organoclay is intercalated, delaminated or exfoliated, there is provided a signicfant improvement in gas/moisture barrier properties of material. Also, when a compatibilizing grafting polymer is employed it desirably provides for grafting of polyolefin to the surface of polyamides. This feauture of the invention has advantages including making homogeneous polymer blend with strong bonds in between phases.

0284The polyolefin-layered silicate polymer nanocomposite material can be made by one or a combination of different strategies including the methods disclosed herein or related methods. As an example, the material can be prepared by non-solvent-based melt-processing method in an extruder at the range of temperatures from at least about 190°C, preferably from between about 190°C to about 260°C. The compounding provides sufficient homogenization, shearing, and mixing of ingredients without noticeable molecular weight degradation of polymer-blend components.

0285As mentioned, the polyolefin-layered silicate polymer nancomposite materials provide advantages including displaying superior mechanical as well as gas-barrier properties. Without wishing to be bound to theory, it is believed that presence of the high aspect ratio barrier layers in the path of the diffusing gas leads to much larger effective diffusion distances for the gas species (e. g., oxygen, water vapor), and creates nanocomposites with excellent gas-barrier properties. Improvements in tensile strength, mechanical durability, impact resistance, abrasion resistance are also obtained as a result of forming nanocomposites from the neat polyolefin. Additional advantages of prefened materials include unprecedented impact resistance; exceptional gas and moisture barrier; maintenance of reasonable optical transparency; thermoformability via techniques such as injection molding and sheet extrusion; recyclability.

0286See Example 12 below regarding more prefened polyolefin-layered silicate polymer nancomposite materials

0287The following examples are provided to point out prefened aspects of the invention and are not intended to be indicative of the scope of the invention. Example 1- ORMLAS Syntheses

0288The ORMLAS synthetic layered silicates were prepared by our standard self- assembly route by the titration of A1C1₃ and the organotrialkoxysilane in EtOH with NaOH.

0289Three ORMLAS were prepared by the following standard route by the titration of A1C1₃ and the organotrialkoxysilane in ethanol with NaOH. The XRD patterns for the alumino- octyl, dodecyl, and octadecyl silsesquioxanes are shown in Figures 5, 6, and 7, respectively. The patterns clearly show an increase in d-spacing (25.1, 37.5, 53.5 A respectively), as well as improved crystallinity, as the organic chain length is increased. Thermal analyses as described below showed the effect of chain length on the thermal stability of these materials. Previous TGA experiments on the dodecyl analogue have shown that the layered structure is intact up to temperatures of 350 °C in either air or inert atmosphere. An increase in organic chain length is likely to lead to a better dispersion of the silicate layers, and to a more delaminated nanocomposite. The increase in hydrophobicity will also yield better interactions with hydrophobic polymers.

0290A particular goal of these studies was to increase the aspect ratio of the layered silicates by increasing the length of the individual silicate layers of the ORMLAS materials. Impact on the effect of plate size (aspect ratio) on gas barrier and thermo- mechanical properties of the nanocomposites can also be addressed.

0291A prefened method of making the ORMLAS was as follows: An aqeous solution of of NaOH (0. IM) was added dropwise with vigorous stirring to A1C13

0292(6.04g, 25mmol) and dodecyltriethoxy silane (16.63g, 50mmol) in ethanol (250ml) to a pH of 5.5 at room temperature. A white precipitate that formed was allowed to age in solution for 16 hours. Then the solid was filtered, washed with water, and dried at 90°C for 6 hours. More particular details about the mixed ORMLAS synthesis is as follows:

0293The synthesis for the mixed ORMLAS materials was the same as that for the standard ORMLAS except that a mixture of the organosilanes were added. For example, for a ORMLAS material with a 1 :1 ratio of methyl: dodecyl, a 1 :1 molar ratio of methyltriethoxysilane and dodecyltriethoxy silane were used in the synthesis.

0294For additional disclosure relating to making the ORMLAS see Ukrainczyk, L. et al. Materials Research Society Symposium on 'Nanocomposites of Layered and Mesoporous Materials, Boston, MA, December, 1996; Fukushima, Y. and M. Tani, J. Chem. Soc. Chem. Commun. pg. 241 (1995); and Ukrainczyk, et al. J. Phys. Chem. B. 101 : 531 (1997).

0295As discussed, Alumino n-Dodecylsilsesquioxane, Alumino n-Octadecylsilsesquioxane, and Alumino n-Phenylsilsesquloxane were synthesized using the described template sol-gel approach. These ORMLAS materials are layered alumino-silicate structures having dodecyl, octadecyl and phenyl organic modifying groups, respectively in the interlayers, connected to the Si atom through Si-C bonds. X-ray diffraction patterns of the three ORMLAS materials are shown in Figures 5-7. Alumino-Dodecylsilsesquioxane displays the most ordered structure followed by

0296Alumino-Octadecylsilsesquioxane and Alumino- Phenylsilsesquioxane respectively. Very shaφ peaks reflecting a high degree of order in the layered structure are obtained for Alumino-Dodecylsilsesquioxane. A layer spacing of up to 3.9 nm is obtained from the XRD pattern. Four orders of the basal reflections are observed. The lack of non-integer orders of basal spacing also implies an ordered lamellar structure. The Alumino-Phenylsilsesquioxane does not show an ordered structure. This observation is consistent with our experience with the nature of ordering in ORMLAS materials.

0297A Transmission Electron Micrograph clearly showing the layers in

0298Alumino-Dodecylsilsesquioxane powder is displayed in Figure 9. The powders were dried in air at -75 °C, were dispersed in ethanol and placed on Cu grid for placing inside the microscope. The TEM picture was obtained at 120 kV, and at a magnification of 200K. The bar in the bottom right hand side represents 20 rim on the picture. Hence, an estimate of the layer spacings has easily been obtained. The layer spacing of (~ 4 nm) revealed in the micrograph matches that obtained from the XRD patterns (Fig. 5A).

0299The above-referenced ORMLAS synthetic methods have been improved. For example, it has been found that alumino - dodecylsilsesquioxane has consistently yielded the most well-ordered layered structure. Thus much standardization and streamlining effort has been applied to this organic modification. AICI₃ and Dodecyl triethoxy silane were used as sources for Al and Si respectively. Their electrostatic interactions were controlled by adjusting the pH using NaOH. Ethanol was used as the solvent. The synthesis process is simple and consistent, and yields layered structures reproducibly.

0300Accordingly, the present invention also features methods for modifying spacing between the inorganic silicate layers of ORMLAS which method includes adjusting the pH of a solution comprising the ORMLAS under conditions that enable acheivment of the desired spacing. As discussed, prefened d-spacing can be determined by TEM or other suitable technique.

0301Example 2 -Synthesis of ORMLAS with Lower Organic Content

0302A. ORMLAS It has been found that the ORMLAS materials that give the best dispersion in a polymer matrix are those prepared with long chain alkyls. It was found, however, that the glass transition temperature (T_g) increased dramatically with increased clay loading. This will often be detrimental to heat distortion and may negate benefits obtained by good clay dispersion. Although not wishing to be bound by theory, one reason for this is likely due to plasticization caused, e.g., by the large amount of organic within these synthetic clays. In order to lower the organic content within these clays, two synthetic methods were developed. Since large d-spacings were prefered, silane precursors with relatively long chain alkyl groups were used But, some of these silanes were replaced with shorter chain alkyls as well as non-alkyl groups such as methyl.

THE REST OF THIS PAGE IS LEFT BLANK INTENTIONALLY

0304Table 1. ORMLAS Materials with Lower Organic Content

0305<img file="WO0078540A1_D0002.tif" />

0306Assuming the standard XRD test suggests a significantly layered structure, the resulting nanocomposites will have a much lower extraneous organic content. This will alleviate the problem with the lowering of T_g observed for ORMLAS nanocomposites.

0307B. ORMLAS Materials with Lower Organic Content

0308Low organic content ORMLAS clays were synthesized by adding various amounts of a long chain silane along with a short chain silane. In each case, the long chain was dodecyl (Cι₂) and the short chain was methyl (Ci). The results of these syntheses are shown in Table 2, below, for methyl. The table includes the yields (measured and theoretical), the XRD peaks (001, 002, 003, along with the full width half maximum (FWHM), the mass loss from the TGA, and the elemental analyses. This data take to first determine if the layered phase was formed, how crystalline it is, and whether or not the short chain silane is incoφorated within the structure.

0309It appears as if the layered phase is formed up to the inclusion of at least 50% of the methyl silane. The d-spacing decreases regularly with the increase of methyl content. This is consistent with a relaxation of the ₂ chains with less organics holding the layers open. The amount of mass loss from the TGA, the consistent yield obtained, and the elemental analyses are consistent with the incoφoration of methyl into the structure. Table 2. Lower organic Cι₂ ORMLAS Synthesis as a function of the Addition of

0310Methyltriethoxysilane

0311<img file="WO0078540A1_D0003.tif" />

0312Meas. = Measured Theo = Theoretical

0313Figure 12 is a table showing a list of alkyl and phenyl ORMLAS materials and d-spacings.

0314Example 3 -Synthesis of Phosphonium Exchanged Clays

0315Phosphonium Clays

03161. The phosphonium exchanged clays using tetraoctyl, dodecyltriphenyl, and tetra phenylphosphonium showed great promise due to their thermal stability. However in some instances there was minimal intercalation or exfoliation with Ultem during extrusion. Thermogravimetric analysis showed that they had very high thermal stability. The onset of exothermic mass loss for these materials occuned above 300°C and the peak of the exotherms appeared above the extrusion temperature for Ultem. This thermal stability is highly desirable making them usable for compounding with polyetherimide and other high temperature thermoplastics. Also, when these three phosphonium clays were extruded with Ultem, there were no signs indicative of burning or charring either by visual inspection, or by TEM.

03172. Positive results for intercalating various polymers within the Cι₆ phosphonium clays were observed. It was thought to be helpful to use longer chain phosphoniums. Prefened phosphoniums for use in this example were available commercially or were made de novo.

0318Cι₈ tributyl phosphonium bromide was prepared via direct reaction of equimolar amounts of octadecyl bromide (2.676g, 8.02 mmol) and tributylphosphine

0319(1.624g, 8.02 mmol) in toluene (10 ml). The reaction was refluxed for 16 hours, after which the solvent was removed in vacuo leaving a crystalline solid. This was recrystallized in toluene / ether to a fine white powder.

0320CH₃(CH₂)₁₇Br + (CH₃(CH₂)₃)₃P *~ <img file="WO0078540A1_D0004.tif" /> Br^"

0321To prepare the phosphonium exchanged montmorillonite, the phosphonium was exchanged with Na⁺ within natural clay. Na⁺ montmorillonite (20g) was sonicated with 1000 ml of deionized water in an ultrasound bath at 80°C for 1 hour. One and half equivalents of the as-synthesized Cι₈ tributylphosphonium bromide (16.07g, 1.5 eq) dissolved in 20 ml ethanol was added resulting in a white precipitate. This was stined for 16 hours, then filtered and washed with 2000 ml H₂O and 1000 ml EtOH.

0322The resulting XRD pattern showed peaks conesponding to a d-spacing of 21.4

0323A.

0324The XRD results from the nanocomposite of the three previously prepared phosphonium clays indicate that there was incomplete or no exfoliation of the silicate layers. Therefore, new clays were prepared with phosphoniums having longer alkyl groups. These new clays were prepared by ion exchange of Na Montmorillonite (lOOcec/lOOg) with hexadecyl (C16) triphenylphosphomum bromide and C16 tributylphosphonium bromide. This was accomplished via first an aqueous suspension of the clay in an ultrasound bath to break up the particles, then adding 2x excess of the phosphonium bromide, resulting in a white precipitate. After stirring for one day, this solid was filtered, washed with water, and air-dried. The XRD results for these materials are shown in Table 3 below.

0325Table 3. XRD Results for Phosphonium Exchanged Clays

0326<img file="WO0078540A1_D0005.tif" />

03273. Lower Exchanged Phosphoniums

0328To help reduce or eliminate an undesired lowering of the glass transition temperature (T_g), organic content of particular nanocomposites was reduced by lowering the amount initially used for the ion exchange of the natural clays. The method outlined above for ion exchange was followed, except lower amounts of the phosphonium bromide were used as shown in Table 4, below.

0329Table 4. XRD Results for Low Exchange Ci₆ TributylPhosphonium Clays

0330<img file="WO0078540A1_D0006.tif" />

0331As can be seen from Table 4, above, the d-spacing for the lower-exchanged phosphonium clays clearly decreases with lower phosphonium content. This is consistent for a clay with less organic pillaring the layers apart. Each of these materials was extruded with Ultem 1010, as shown elsewhere in this disclosure. All of them result in intercalated or exfoliated nanocomposites. That is, increased d- spacing was observed. The lower (underexchanged) phosphoniums were made as follows: Sodium montmorillonite (lOOg, O.lmol Na+) with an exchange capacity of 100 meq/lOOg was added to water (1 liter). This was treated in an ultrasound bath at 80C for 1 hour. Upon addition of hexadecyltributylphosphonium bromide (101.53g, mmol, 0.2 mol) dissolved in ethanol (500ml) a white precipitate formed. After stirring for 8 hours, the solid was filtered, washed with water (1 liter) and ethanol (1 liter), and dried at 90C for 6 hours. The lower exchange phosphonium clays were prepared in the same manner except with lower amounts of the phosphonium salt.

0332See also the TEM image of Figure 10 showing tetraoctyl phosphonium exchanged Clay/Ultem nanocomposite.

0333Example 4-Extruded Polymer / Layered Silicate Nanocomposites

03341. Polyetherimide (PEI) Nanocomposites

0335Several sets of extrusions were performed using Ultem 1010 polyetherimide as the polymer matrix. The use of ORMLAS synthetic clays showed no peaks in the XRD patterns, implying a complete dispersion within the polymer up to a level of at least 10%. The phosphonium-exchanged natural clays have not been completely dispersed. The use of a Cι₆triphenyl phosphonium-exchanged clays result in a decrease in d-spacing upon nanocomposition. This has been observed previously for phenyl phosphonium clays and may be a combination of intercalation and collapse of the clay layers. Conversely, the Cι₆ and Cι₈ tributyl phosphonium clays result in a increase in d-spacing showing classic intercalation behavior. The fully exchanged Cι₈ clays do not increase the separation of the layers significantly over that of the ₆ analogues, however they have very shaφ peaks, indicating a very well ordered material. PEI nanocomposites prepared with lower organic content phosphonium clays prepared displayed an increase in d-spacing as the organic content was lowered, despite the opposite trend in the patterns for the neat clay. The phosphonium clays prepared with a lower organic content for showed comparable patterns upon extrusion with the polymer despite their original dissimilar patterns. Table 5. Polyetherimide Nanocomposites

0336<img file="WO0078540A1_D0007.tif" />

0337The glass transition temperatures (Tg) obtained from DSC experiments for the various nanocomposites are also shown in Table 5, above. The DSC curves for the Ci₆ triphenyl phosphonium nanocomposites show a decrease in T_g with increasing clay content. Without wishing to be bound to theory, this may be due to a large amount of organic present (in the form of phosphonium) causing plasticization. Incomplete washing of the clay during the original synthesis may be one of the reasons for this extra organic present. Conversely, the Cι₈ tributyl and the lower exchanged ₆ tributyl do not show a shaφ decrease in T_g resulting in lower plasticization. The Cι₈ ORMLAS synthetic clay shows a distinct decrease in T_g similar to the other ORMLAS nanocomposites reported earlier. The lowering of T_g is also likely due to plasticization since the ORMLAS materials are intrinsically high in organic content. 2. Polysulfone / Polyarylsulfone Nanocomposites

0338XRD and DSC results for the polysulfone and polyarylsulfone nanocomposites were obtained. The use of Cι₆ butyl phosphonium clay with Udel polysulfone does not show the intercalation behavior observed with the Ultem nanocomposites. The DSC shows minimal loss in T_g as with the Ultem nanocomposites. The use of ₆ phenyl phosphonium clay with Radel polyarylsulfone shows no peaks in the XRD patterns, however, the T_g does decrease dramatically as observed before. Both the Udel and Radel nanocomposites with phosphonium clays were very brittle possibly due to decomposition of the polymer or incomplete intercalation/exfoliation. The ORMLAS clays dispersed well in Udel, however, showed low T_g values.

03393. Nylon-6 Nanocomposites

0340Several new nanocomposites were made using ORMLAS materials as shown below for Nylon-6. See Table 6, below.

0341Table 6. Nylon-6 Nanocomposites

0342<img file="WO0078540A1_D0008.tif" />

03434. Other Polymer Nanocomposites

0344Due to the excellent results in dispersing the C18 ORMLAS within Ultem, this clay was also used with various other polymers. The XRD results for nanocomposites prepared with 5% C18 ORMLAS within these polymers are shown in Table 7, below. In every case, the XRD patterns have no peaks, implying that in every polymer the individual layers of the ORMLAS are separated and disordered within the matrix. This shows the diversity of the ORMLAS materials compared to the natural clays. A typical XRD pattern of one of these nanocomposites is shown in Figure 9. The reason for the ease of dispersion of the individual layers comes from the small size of the platelets. This can be seen in the TEM pictures where the particles on the order of 50- lOOnm in diameter. This is lOx smaller than the size of the platelets in natural clays that are on the order of 1 micron. This smaller size decreases the effective Van der Waal's forces between adjacent layers, allowing their separation. The use of the long chain alkyl groups in ORMLAS also yields a much higher density of the waxy organic moieties than can exist within a natural clay.

0345Table 7. XRD Results for Extruded Polymer / C18 ORMLAS Nanocomposites

0346<img file="WO0078540A1_D0009.tif" />

0347Additionally, use of polyphenylene sulfide (PPS), polyphthalamide (PPA), and polycarbonate (PC) did not show peaks as determined by this analysis.

0348Example 5 - DMA Results for Selected Nanocomposites The DMA curves for neat Nylon-6 and a 5% Cι₈ ORMLAS / Nylon-6 nanocomposite are shown in the following graph. These results show a significantly higher storage modulus before the T_g of the nanocomposite as compared to the neat polymer. Moreover, the rubber modulus after the T_g is double to triple that of the neat polymer. Interestingly, the DSC curve for the nanocomposite earlier did not show a distinct T_g. This enlightens our understanding of how a polymer will have a HDT significantly higher than its T_g. Based on the graph, a bar with a load of 1000 MPa put on a bar of Nylon would theoretically distort at about 60°C, whereas the same load put on a bar of the nanocomposite would distort at about 130°C. Thus the Nylon nanocomposite will have an enhanced use temperature over the neat resin. Example 6- Additional Analysis

03491. Transmission Electron Microscopy (TEM)

0350Several nanocomposites were studied for the dispersion or exfoliation of the clay within the polymer matrix. Figure 8 shows the TEM picture of a typical ORMLAS material. It is easy to see the individual stacked up layers within each clay particle. Upon extruding within Ultem, the individual silicate layers are separated throughout the polymer matrix. These individual layers are shown in the TEM of the Ultem nanocomposite with C18 ORMLAS. See Figure 9. The enlarged inset picture shows several of the layers that are still loosely aggregated, however, the large portion of layers are completely separated from each other. The TEM of tetraoctyl phosphonium exchanged clay nanocomposite is shown in Figure 10. Although the XRD of this material does not show intercalation or exfoliation, the clay is very nicely dispersed throughout the polymer. Note the difference in the size and moφhology of the ORMLAS layers compared to those of the natural clay. A sepiolite / Ultem extruded nanocomposite is shown in Figure 11. This material is not a layered clay, but a rodlike silicate. Despite not having layers that can exfoliate, the material disperses evenly throughout the matrix, and has excellent orientation.

0351Dynamic Mechanical Analysis was performed on neat Udel (polysulfone) and a Udel / 10%Cι₆ butyl phosphonium nanocomposite. The DMA curves for these two samples are shown in the graph provided in Example 5. The HDT calculated for the nanocomposite is about 179.5 compared with the literature value of 174°C for the neat polysulfone. It suggests that the modulus as well as the HDT of Udel polysulfone can be increased somewhat over the values for the neat polymer.

0352See also Figure 20 showing DMA curves for a) neat Udel and b) Udel nanocomposite. Example 7- Solution Nanocomposition

0353A new solution route was used to prepare nanocomposites. This was done to see the high temperature extrusion could be avoided. Also, it is possible that this route may obtain a better dispersion of the various clays. This approach has potential to work very well, since the internal surface of the clays is very organophilic, especially in the case of ORMLAS. The individual silicate layers should exfoliate in solution, as the solvent acts as a surfactant, separating the layers apart.

0354The solution nanocomposition took place by the following procedure. The clay was initially treated in an ultrasound bath for 10-30 minutes with the appropriate solvent for the polymer (CHC1 or CH₂C1₂ was used for Ultem, Udel, PC). This suspension was then added to a predissolved solution of the polymer. The amount of clay was varied between 5-10 mass percent of the total solids. This suspension was then stined for one day, then cast into a beaker or petri dish. The solvent was then evaporated in air, resulting in a free standing nanocomposite film. XRD results for the solution-prepared nanocomposites are shown in Table 8, below.

0355The Southern Clay natural and ammonium exchanged clays (organoclays) were used initially to determine their interaction with Ultem. The Na⁺ clay showed intercalation of polymer by the increase in its d-spacing in the XRD patterns. This is quite suφrising considering that that clay is very hydrophilic. The clay did not disperse well in the solvent, showing a good reason why intercalation occuned, and not exfoliation. The organoclays, Cloisite 25A and 30A (from Southern clay Products) dispersed very well in the solvents and became almost completely clear. Notably, these showed no peaks in the XRD patterns and the resultant films were quite translucent. Heat treatment of these materials (to press samples for DMA) resulted degradation by the burning of the organic portion of the clay, turning the material black and brittle. Although not useful for high temperature engineering plastics, this method using natural and exchanged clays could be very promising for other polymer matrices. When the ORMLAS materials were dispersed into the solvents, the solvents became completely clear, indicating that either the individual layers were completely exfoliated within the solvent or there was a perfect index match for the indices of refraction between the solvent and the clay. The fact that the resulting ORMLAS / Ultem nanocomposites all lost their XRD, provided further evidence for good dispersion. This may be a way to make the nanocomposites as opposed to the melt extrusion process.

0356The final set of clays used with Ultem is the phosphonium exchanged clays. Like the extrusion nanocomposites (vide infra), exfoliation does not occur with the short chain phosphoniums, but do with the long chain analogues. Also, the long chain phosphonium clays disperse very well in the organic solvents whereas those with short chains do not. The interesting observation about the phosphonium clay nanocomposites is that the resultant films were quite transparent, and were substantially less brittle than those prepared with ORMLAS. This may help by giving an impact modifying effect for the material that is lacking with the ORMLAS as described later in the DMA testing section. The C16/phenyl phosphonium Ultem nanocomposite was scaled up and extruded as shown later in the extruded nanocomposite section.

0357Udel /ORMLAS nanocomposites behaved similarly to those with Ultem. Good dispersion or exfoliation occuned in these samples. The phosphonium-exchanged clays, however, did not disperse at all within the Udel.

0358The polycarbonate (PC) had some promising effect with the clay including ORMLAS. The clay could be intercalated or exfoliated within PC, however, the resultant material was very crystalline. DSC experiments run on these nanocomposites showed that PC lost its glass transition temperature (T_g) indicating that it was not amoφhous anymore. Attempts to thermally compression mold these nanocomposites failed as the polymer was not easily processed. The samples were very brittle and did not hold together well. Table 8. XRD Results from Solution Nanocomposition

0359<img file="WO0078540A1_D0010.tif" />

0360Example 8A Thermogravimetric / Infrared Spectroscopy / Mass Spectroscopy Analyses

0361The thermal stability study of various clay samples was analyzed as follows. TGA with concunent IR and MS analyses has been able to determme the relative thermal stability of various organically modified clays and the identity of the combusted organics from these materials. Many new ammonium exchanged montmorillonite samples have been analyzed. The ammonium exchanged clays show similar thermal stability (onset of decomposition between 200-275°C) to those reported previously. These ammonium clays decompose far below the processing temperature (340-360 °C) of the engineering resins (polyimide, polysulfone). TGA with concunent IR and MS analyses was carried out to determine the relative thermal stability of various organically modified clays and the identity of the combusted organics from these materials. The thermal stability in this experiment mimiced the conditions that these materials will face during extrusion. The parameters evaluated regarding the thermal stability of various clays are:

0362A. Effect of the type of clay (provided by Southern Clay Products)

03631. Montmorillonite (CEC 95 meq)

03642. Hectorite (CEC 75 meq)

03653. Sepiolite (CEC 20 meq) This experiment show the relative stability of the organics within the various types of clay. Sepiolite, for example, is a rod-like silicate with channels as opposed to the plate-like layers of montmorillonite and hectorite. Also, we will be able to see the effect of exchange capacity.

0366B. Effect of Chain length i.e., C₆, C₈, C₁₂, Cι₈ alkyl ammoniums

0367The effect of the chain length on thermal stability was examined. If N-C bond is the weakest, we may see no effect of chain length. The longer chains, however, may prevent (or postpone) oxidation.

0368C. Effect of Substitution i.e., Mono vs Disubstituted ammoniums

0369D. Effect of Saturation i.e., Saturated and Unsaturated tallow ammoniums

0370E. Electronic Differences i.e., alkyls vs benzyl

0371With the alkyl group attached directly onto the aluminosihcate layer (Si-C covalent bond) the thermal stability is expected to be substantially higher than the ion exchanged clays. Example 8B- Thermal Stability of ORMLAS Materials

0372The thermal stability of ORMLAS materials is key to the creation of superior high usetemperature and high performance nanocomposite systems. Their thermal stability has been characterized using Thermo-Gravimetric Analysis. Also, the maintenance of layered structures has been ascertained up to temperatures of 350°C using XRD analyses after a series of heat treatment runs under nitrogen and air atmospheres. Our objective was to ensure that the layered structures are maintained at temperatures used for melt-processing of high use-temperature polymers.

0373A. Thermo-Gravimetric Analysis

0374Thermogravimetric Analysis (TGA) of Alumino - Dodecylsilsesquioxane under nitrogen atmosphere is shown in Figure 13. The x-axis in Figure 13 displays the time of heating, the right hand side of the y-axis displays the temperature, and the weight is displayed on the left-hand side of the y-axis. The heating schedule comprised a ramp up to 250°C at 20°C/minute, a hold at 250°C for 10 minutes, then a ramp up to 350°C at 20°C/minute, and a hold at 350°C for 10 minutes. The heating schedule was generated to effectively simulate the heat conditions during the nanocomposite fabrication.

0375The Alumino-Dodecylsilsesquioxane powder was dried only to about 75°C before the TGA. At this stage it contains a lot of ethanol (solvent) and water which are evolved as during the initial stages of the heating. There is a weight loss of only about 2% during the 10-minute hold at 250°C, and only about 4% additional weight loss during the 10-minute hold at 350°C. Alumino-Dodecylsilsesquioxane ORMLAS material displayed good thermal stability in the temperature range of up to 350°C under inert atmospheres, with a total weight loss of only about 11%. Most of the weight loss can be accounted for by the loss of water and solvent, with very little degradation of the organic (dodecyl) groups attached to the silicon atoms. These ORMLAS materials were therefore expected to retain their layered structure under these conditions. B. Effect of Heat on the Layered Structure of ORMLAS Materials

0376The effect of heat on the ordered layered structure of the ORMLAS materials has been investigated by obtaining the X-ray Diffraction patterns of

0377Alumino-Dodecylsilsesquioxane powder after a series of controlled heat treatments. The TGA provided clear evidence that these materials sustain heat treatment up to 350°C under inert atmosphere without damage to the organic chains. Also, the retention of the Si-C bonds at these temperatures is well-documented in the literature. An objective in these experiments was to find out whether the layered structure of the ORMLAS material is maintained at the thermal conditions used for direct melt processing of the nanocomposites with high performance polymer matrices. As in the design of the heating schedule for the TGA, this series of heat treatments was designed to simulate the thermal conditions in the extruder during nanocomposite fabrication.

0378The powders were placed in alumina crucibles, and were heated to various temperatures under nitrogen or under air. XRD patterns of the powders were then obtained, and are shown in Figure 14A-G). The layered structure of the ORMLAS material, viz., Altunino - Dodecylsilsesquioxane, shows excellent thermal stability up to 350°C under inert as well as air atmospheres. The XRD pattern of Alumino - Dodecylsilsesquioxane powder obtained after drying in air at 75 °C is shown in Figure 14 A. A shaφ peak indicating a d-spacing of 3.75 nm is evident in the figure, along with three more rational orders of the basal reflection. This peak gets more intense after heat treatment at 150°C for 10 minutes limier nitrogen, with the d-spacing slightly reduced down to 3.55 run (Figure 14B). A shaφ intense peak with a d-spacing of 3.29 nm is obtained after heat treatment at 200°C for 10 minutes under nitrogen (Fig. 14C). Shaφ XRD peaks showing the retention of the layered structure with heat treatment at 250°C and 350°C under nitrogen and air atmospheres are shown in Figure 14D-G. One trend evident from these patterns is a reduction in the d-spacings of layers with increasing degree of heat treatment.

0379This is shown in the following Table 9:

0380<img file="WO0078540A1_D0011.tif" /> Nevertheless, the layered structure is retained. A computer simulation of the minimum breaking. Hence a good coverage of the silicate layers by the organic groups is obtained, energy configuration of the dodecyl chains within the layers has also been performed. It predicts that full surface coverage of the silicate layers by the organic (dodecyl) groups is obtained with only 56% of the Si-C bonds in place. Sol-gel processing of the ORMLAS materials protects the Si-C bonds.

0381C. Thermal stability of clays

0382TGA with concunent IR and MS analyses will be able to determine the relative thermal stability of various organically modified clays and the identity of the combusted organics from these materials. The thermal stability in this experiment will hopefully mimic the conditions under which these materials will undergo during extrusion conditions. These experiments were all performed in flowing high purity nitrogen or oxygen. The TGA DTA curves for several representative samples, an ammonium exchanged montmorillonite, a phosphonium exchanged montmorillonite, and an synthetic ORMLAS, are shown in Figure 2. The first exothermic peak in the DTA pattern and concunent mass loss in the TGA curve listed in Table 10, below conespond to the combustion of the organic moiety within the layers. The onset of mass loss is also noted, although the IR spectra run in parallel indicate that minimal organic material is lost from the samples until the endothermic peak noted. The first experiment was to compare the relative thermal stability of various natural clays. This was done with three clays, (a) montmorillonite, (b) hectorite, and (c) sepiolite exchanged with dihydrogenated, dimethyl tallow ammonium chloride. The sepiolite appears to have a substantially higher thermal stability than montmorillonite and hectorite, however, the onset of decomposition occurs much earlier. It should be noted that sepiolite is not a layered silicate or clay, but a rod-like silicate, and its exchange sites are likely in pores rather than between layers. Thus, intercalation / exfoliation of a polymer or other organic between the layers is not possible with this structure.

0383A comparison of the thermal stability of a monoalkyl and dialkyl substituted ammonium shows that the doubly substituted is more stable. This is exhibited between the decomposition of (d) monohydrotallow and (a) dihydrotallow exchanged montmorillonite. Although the onset of decomposition is similar between the two, the peak of decomposition is more that 50°C higher in the disubstituted analogue. The electron donating ability of the alkyl chains stabilizes the positive charge on the N core. Thus even more alkyl groups should deter decomposition of the organic moiety.

THE REST OF THIS PAGE IS LEFT BLANK INTENTIONALLY

0385Table 10. Thermal Stability of Various Clays by TGA/DTA Analyses

0386<img file="WO0078540A1_D0012.tif" />

0387A further interesting note is the comparison of (d) hydrotallow (mixture of C14, C16, and C18) compared with (e) octadecyl (pure C18). The stability of the pure C18 is notably higher, and also has a significantly shaφer decomposition point. This is also observed, although to a lesser extent, with coco (C12, and others) and dodecyl (pure C12). The longer chain alkyl (e vs g) does have a small effect in increasing thermal stability. Comparison of the thermal decomposition of the phosphonium vs ammonium exchanged clays shows that the phosphonium analogues (h,i,j) have significantly higher stability. See Table 10, above. This can be explained by the better ability of P than N to delocalize the positive charge. Also, the core (P⁺, where the decomposition likely originates) is protected by multi-substitution. The material with the highest thermal stability is the tetraoctyl, which has four long alkyl chains protecting the core. The alkyl chains are all electron donating, a property that has been shown earlier to stabilize the positive charge, and thus prevent thermal decomposition.

0388The ORMLAS materials (k,l,m) have substantially higher thermal stability than do any of the natural clays. The TGA curves for these materials are very broad with a early onset point and slowly increasing mass loss. The DTA curves, however, are fairly shaφ and similar for the samples tested indicating that the organics within these clays are very stable and decompose at a very precise temperature. The fact that the thermal stability of each ORMLAS is the same indicates that the material starts to decompose when the Si-C bond is broken. Thus the stability is independent of chain length. The high stability of these materials is due to the strong Si-C bonds in the structure as compared with N^-C as in the natural clays. All of the natural clays have cationic organic moieties that are very susceptible to decomposition. The neutral surfactant that is actually covalently bonded to the silicate surface gives a critical stabilizing effect.

0389Each of the ORMLAS samples has an exothermic peak and a small mass loss between 180-206 °C. The IR spectra at this temperature show that the material coming off is likely not organic or at least not alkyl derived organics. Further, mass spectroscopy confirms that very little organic material is combusted below 500 °C in any ORMLAS.

0390Several of the ORMLAS materials were also tested for their thermal stability in an O₂ atmosphere. The decomposition for each occurs at a significantly lower temperature than they do in N₂. It is interesting that the alkyl ORMLAS (l,m,n) all begin to decompose at about the same temperature in O₂ (about 190°C). The similar thermal stability of these materials parallels the result of the experiment obtained under N₂. The highest stability material in the series is the one prepared with (p) Phenethyl silane. Even the addition of Phenethyl silane to the reaction mixture of Dodecyl ORMLAS increases its thermal stability substantially (q,r,s).

0391See also Figures 18A-C showing XRD spectra for Montmorillonite ion- exchanged with various phosphonium cations.

0392Example 9- Nanocomposite Compounding Methods As discussed above, silicate compositions of this invention and particularly nanocomposites can be made using conventional extuder implemtations. Such an extruder is preferably a single or twin screw extruder such as those generally known in the field. In situations in which a a twin screw extruder is used, the prefened embodiment shall make use of a co-rotating twin screw extruder as follows.

0393The twin co-rotating extruder shall consist of screws with 3 distinct sets of element types including: a) conveying elements, b) kneading elements, c) mixing/dispersion elements. In particular, 5-30% of the length of each screw shall consist of kneading elements; 5-15% of the length of the screw shall consist of mixing/dispersion elements; and 55-90% of the length of the screw shall consist of conveying elements.

0394It is often important to maintain a carefully defined pressure profile inside the extruder. This pressure profile includes high pressure in the kneading section for a short duration, layered silicate shall be added at a low pressure area after the neat resin has been melted, the mixing section shall be at lower pressure than in the kneading section, the conveyance section shall be approximately three times longer than the kneading section. More specifically, to make the nanocomposite, the screws shall exhibit a length over diameter ratio (L/D) of between 30-35 to 1. The screw speed shall operate between 50-166 RPM.

0395There are generally two prefened methods of feeding the materials to be compounded into the extruder, namely by premixing the plastic resin with the nanoloyered silicate and by feeding the two separately.

0396In the cases in which the desired nanocomposite includes polymer blends or alloys, the polymers (two or more) may also be premixed or introduced along the length of the extruder.

0397For example, the polymer and the layered silicate shall be gravimetrically fed using a starve feeding methodology. Starve feeding introduces the material to be mixed using a controlled rate system. Use of starve feeding is essential to controlled mixing of the two components. The layered silicate shall be fed approximately 50% along the length of the extruder in order to allow the neat resin to reach its melting point.

0398One good way of feeding involves first feeding the thermoplastic resin in powder or pellet form. The extruder shall be preheated to a temperature set at 99%- 110% of the melting point of the neat resin. The neat resin shall be at 99%- 110% of its melting point at the point of intercalation or exfoliation. Such temperature profile shall be maintained during the mixing (compounding).

0399The exiting compounded (resin plus layered silicate) resin shall have a temperature of 102-110% of the melting point of the neat resin. In order to obtain compounded material with optimum properties, it is essential to extract entrapped volatiles in gaseous form within the last 10% of the length of the extruder.

0400The exiting compounded shall go through a mole which shall be able to impart certain geometric configuration on the thermoplastic compound. Such geometry may be in the form of a rod, film, sheet, or other complex shapes such as blow molded or extrusion blow molded article of manufacture.

0401For applications in which an article of manufacture is to be made, that article exiting the extruder shall be quenched to a temperature of 10-100°C using liquid (such as water) or gaseous material (such as nitrogen or air).

0402A. Al n-Dodecylsilsesquioxane and Nylon 6 Nylon-6 has been used as the benchmark polymer matrix due to the vast amount of data avails le on Nylon-nanocomposites. The nanocomposites were fabricated via solvent free Direct melt processing using a twin-screw extruder. The extruder was maintained at a temperature high enough to ensure the presence of a polymer melt (235'C for Nylon-6). A residence time of 5-10 minutes at the melt temperature was used. A purge of nitrogen was maintained during the heating. The extruder was cleaned between the runs by passing pure polymer through.

0403a) ORMLAS

0404X-ray diffraction pattern of the nanocomposites made using 5 wt % of Al n-Dodecyl stlsesquioxane with Nylon-6 does not show any crystalline features which is indicative of a good dispersion of the ORMLAS layers in the polymer matrix.

0405Further evaluation of the effect of extrusion on the layered structures of the ORMLAS materials was done by obtaining XRD patterns of the powder mixtures of Nylon-6 with the ORMLAS materials before and after extrusion. Figures 15A-C show the patterns of mixtures of Nylon-6 powder with 5 wt.% (Figure 15 A) and 7 wt.% (Figure 15B) Al n-Dodecyl silsesquioxane powder before extrusions A shaφ peak conesponding to a ~ 3.9 nm is evident in both patterns, and its position matches well with that of the peak in the pattern of neat Al n-Dodecyl stlsesquioxane (Figure 15 A). This peak disappears after extrusion (Figure 15C). Similar trends were obtained with much higher contents (15 and 20 wt.%) of Al n Octadecyl stlsesquioxane.

0406The structure of the Nylon-Dodecyl ORMLAS nanocomposites was directly examined using Transmission Electron Microscopy in order to observe the state of the ORMLAS layers within the polymer. The particular nanocomposites examined had 15 weight % Dodecyl Silsesquioxane in a Nylon matrix, and were fabricated under a nitrogen purge at 235°C with a residence time of 10 minutes in the extruder. Figure 16 A-B show the TEM pictures displaying an exfoliation of the Alumino- Dodecylsilsesquioxane layers within the Nylon matrix. The bar on the bottom of the picture represents a length of 50 nm. Individual ORMLAS layers well-dispersed within the Nylon matrix are evident in the micrograph. Thus, the surface chemistry of the ORMLAS materials provides favorable interactions with the Nylon matrix. These favorable molecular interactions result in the exfoliation of the individual layers within the polymer matrix. Such control of the surface chemistry is a very desirable achievement.

0407The intimate molecular interactions of the ORMLAS layers levity the Nylon matrix are also indicated by the DSC (Differential Scanning Calorimetry) measurements (Figure 17A-B). Figure 17 (A) shows the DSC plots of Nylon-6 and Nylon-ORMLAS nanocomposite obtained at a heating rate of 20°C/minute. A difference of- 15°C in the melting temperature is evident, and was repeatedly observed. This was inteφreted to be a kinetic effect of the molecularly dispersed ORMLAS layers on the flow of the polymer chains. Indeed, a slower heating rate (100°C/minute) lowers the observed peak by ~15°C (Figure 17B). This observation suggest that an extremely intimate mixture of the ORMLAS layers with the Nylon matrix is formed in the nanocomposite.

0408Having made synthetic layered silicate phase which provides a favorable intenacial chemistry as well as a more thermally stable interface, ORMLAS and higher use-temperature resins have been combined. We have fabricated nanocomposites using Polyetherimide (Ultem 1000 and Ultem 1010) as the matrix. These polymer resins have a Heat Distortion Temperature (HDT) of about 200°C, and can be extruded at about 335-340°C. This is ideal to examine any enhancements in thermal and mechanical properties of nanocomposites in the range of 200-250°C.

0409B) Phosphonium Clays The ion-exchanged clays were mixed with Nylon and with Ultem 1010 (Polyetherimide) resin, and nanocomposites were fabricated in a twin-screw micro-extruder under a purge of nitrogen. Clays containing phenyl functionalities show poor dispersion in both Nylon and in Ultem matrices - as evidenced by the XRD patterns of the extruded product (Figure 19A). Shaφ remnant peaks related to the layered anangement of the clays within the polymer clearly show that the phenyl-clays are not dispersing in the polymer matrix. This is consistent with our observations of poor dispersion of phenyl-ORMLAS materials in polymer matrices. The XRD pattern indicates a much better dispersion of the tetraoctyl-exchanged clays in the polymers (Figure 19B). By creating a favorable chemistry at the interface, Tetra-Octyl phosphonium therefore provided a success for this approach.

0410It will be understood that the information provided in this example can be readily modified to suit an intended result. For example it will be helpful in some situations to optimize pressure, heating and mixing profiles within a selected extruder implementation to facilitate a particular performance characteristic. Such optimization is within the skill of those and this field and will not require undue experimentation to achieve.

0411Example 10- High Barrier Nanocomposites

0412As discussed, the invention provides a variety of high gas-barrier nanocomposites. Such nanocomposites are made by one or a combination of approaches including compounding at least one suitable layered silicate phase with at least one base polymer resin such as PET, polyolefms, EVOH, ect. By adjusting the chemistry and the processing conditions, e.g., to suit an intended use, these nanofillers naturally self-assemble (i.e. stack up) through the thickness of the plastic sheet. The typical feature size of each filler platelet is approximately 1 nm (one billionth of a meter) in thickness, and 100-500 nm in length. The separation distance between each layer is preferably between 3 to 10 nm.

0413The nancomposites provided have several important characteristics including ultrafine feature sizes, low loading of the layered silicate phase, light weight, and processibility via the conventional polymer processing techniques. Examples of such techniques are disclosed below and in Example 9 above. In most instances, the silicate layers of the nanocomposites do not adversely affect the impact strength or the puncture resistance of the base resin. Instead, they generate a tortuous path for the diffusing gas species, thus significantly increasing the diffusion distance through the thickness of the plastic. Accordingly, the high gas-barrier nanocomposites are highly useful and particularly enhance the barrier properties of commodity polymers.

0414More specific information relating to making and using the high gas-barrier nanocomposites is provided below.

0415A. Silicates

0416Several types of organically modified natural layered silicates were used. Following is a standard procedure for the ion exchange procedure of two standard organically modified clays. About 100 g of sodium montmorillonite (with 100 meq / lOOg exchange capacity) was ion exchanged with (i) 49.07 g (100 mmol) of dimethyl hydrogenated tallow-2-ethylhexyl ammonium bromide, and (ii) 42.25 g (100 mmol) of methyltallow bis-2-hydroxyethyl ammonium bromide. The Na⁺ montmorillonite was dispersed in 4 liters of water at 80°C with the aid of ultrasonic treatment. Upon the addition of a solution of the alkyl ammonium salt, a precipitation of a white solid was observed. After stirring for 24 hours, the solid was filtered and washed with copious water until the filtrate had a pH of 7. The solid was dried at 80°C for several hours, ground into a fine powder, and the smallest particulate was obtained through a 100 mesh sieve. The finely ground clays with an average particle size of about 1 micron were used.

0417As discussed earlier, this ion exchange with the organic groups gives the silicate layers an organic character, and creates favorable interactions with organic polymers. The creation of suitable interactions is one important factor in obtaining a nanoscale dispersion of the silicate layers, and in the creation of superior barrier and other mechanical and thermal properties. B. Polymer Materials

0418The PET used was Tenite 12822 - obtained from Eastman Chemicals. This particular grade was selected in order to minimize crystallization and orientation in the matrix, which also affect the barrier properties. This grade of PET does not contain any nucleating agents which could promote the crystallization of PET matrix during extrusion. This allows for an isolation of the effects of the layered silicates on the barrier properties.

0419C. Nanocomposite Fabrication Non-solvent based melt extrusion process was employed using a twin-screw extruder to fabricate the nanocomposites. A twin-screw extruder usually provides the necessary shear to ensure homogeneous distribution of the inorganic phase within the polymer matrix. The extruder was heated to a temperature that ensures the presence of a polymer melt.

0420A particular fabrication approach involves melt blending a suitable polymer resin and layered silicate, e.g., about 5 to 10% (w/w) NA⁺-montmorillonite, with the remaining part as PET or a blend or an alloy thereof. The material is added to one extruder and feeding is achieved with a standard sheet die to produce the sheet stock for thermoforming the final parts. The twin-screw extruder is often prefened. The entire process, in production mode, will preferably occur in one continuous step, from melt blending / extrusion to "in-line thermoforming". That is, as the sheet is extruded, it passes over thermoforming molds where the sheet is formed before it gets a chance to cool.

0421In a more specific fabrication approach, the extrusion was carried out at 250°C. A series of PET-nanocomposites and pure PET samples was fabricated under precisely the same conditions. The extruder yielded nanocomposites in the shape of rods, which were then thermoformed into 5 cm x 5 cm films having a thickness of about 12 mils. The thermoforming was carried out at 250°C under high pressure in a press. Three films of each composition were prepared so as to obtain several sets of permeability measurements. See Example 9, above for more specific information relating to compounding the nanocomposites using a conventional extruder implementations.

0422D. PET High Gas-barrier Nanocomposite

0423The results shown below in Tables 11 and 12 demonstrate up to 2 orders of magnitude improvement in oxygen barrier of PET at 0% relative humidity. Significantly, the permeability of the Nanocomposite#2 was below the detection limit of the equipment. Nanocomposite #2 shows a stronger effect (much lower oxygen permeability) because of its higher clay content - 10% compared to 5% clay in the case of Nanocomposite #1.

0424Table 11: Oxygen Permeability of PET and PET-nanocomposites at 0% RH x n Transmiss in2

0425<img file="WO0078540A1_D0013.tif" />

0426RH= relative humidity

0427Due to the increased diffusion distance with the numerous nano-silicate layers in their path, the PET-nanocomposites also show a dramatic improvement in water barrier performance compared to the neat PET resin. The results of the water vapor permeability measurements are shown below in Table 12. Nanocomposites# 1 and #2 in Table 2 are the same films as the ones in Table 11. The results show up to about 20-fold reduction in water vapor permeability. These results are very promising and clearly show the tremendous effect of the nanolayers in reducing the gas permeability of the polymer.

0428Table 12: Water Vapor Permeability of PET and PET-nanocomposites at 90%

RH

0430Water Vapor Transmission (gm 100 in2.day)

0431<img file="WO0078540A1_D0014.tif" />PET= polyethylene tetraphthalate RH- relative humidity

0432E. Gas Permeability Measurements

0433The oxygen and water vapor permeability measurements for the above- mentioned films were carried out at Delmonte Laboratories (Walnut Creek, CA). A 5 cm² circular cross-section of the films described above was masked and used for these permeability measurements. The permeability of the nanocomposite samples was compared directly with that of the pure PET samples.

0434The oxygen permeability data shown above in Table 11 is especially impressive. The results indicate up to a 100-fold reduction in the oxygen permeability of PET at 0% relative humidity. In fact, the permeability of the Nanocomposite#2 was below the detection limit of the equipment. Nanocomposite #2 shows a stronger effect (much lower oxygen permeability) because of its higher clay content - 10% compared to 5% clay in the case of Nanocomposite #1.

0435F. X-ray Diffraction Analysis

0436The following is an analysis of the permeability data shown in Tables 11 and 12 in light of X-Ray Diffraction (XRD) analysis. As discussed throughout this application, XRD can provide useful information about the silicate layers within a nanocomposite.

0437X-ray diffraction analyses was performed on the layered silicate materials as well as on the PET nanocomposites to investigate the state of the layered silicates upon extrusion with the PET. Information about the state of the individual layers within the polymer matrix is thus obtained.

0438The patterns of the two organically modified layered silicate materials (clays) are shown in Figures 24A-B. The clays show a layered structure with an interlayer spacing of ~ 1.8-1.9 nm (Figure 24(a) and 24(b)). The XRD patterns of PET- nanocomposites containing 5% and 10% clay respectively are shown in Figure 24(a) and 25(b). These patterns clearly indicate that the layer spacing has increased from 1.8 nm in the pure clay to 3.2 nm in the nanocomposite. This indicates the intercalation of polymer into the interlayer spacing of the clays, and hence the formation of ordered intercalated hybrids. A shaφ peak indicating ordered intercalates with a layer spacing of about 3.2 nm is evident, and is seen to get stronger for the 10%-clay nanocomposite sample (Nanocomposite sample #2 in Tables 3 and 4). Clearly, the original interlayer spacing of the neat clays (i. e., 1.8-1.9 nm) is enhanced to 3.2 nm by the intercalation of PET within the layers, therefore leading to intercalated nanocomposite structure.

0439G. Discussion

0440The model illustrated in Figure 23 and the observed increased diffusion distance of the gaseous species of the nanocomposites provided in Tables 11 and 12 is consistent with numerous nano-silicate layers in the path of the gas. For example, the permeability of water vapor undergoes a dramatic reduction in the nanocomposites compared to the neat PET resin. The results of the water vapor permeability measurements are shown below in Table 12. Nanocomposites# 1 and #2 in Table 12 are the same films as in Table 11. The results show up to about 20-fold reduction in water vapor permeability. These results are extremely promising and clearly show the tremendous effect of the nano layers in reducing the gas permeability of the polymer.

0441The high gas-barrier nanocomposites of this invention can be used alone or in combination with other components in a wide spectrum of manufactured articles. Prefened articles are those in which good barrier properties are desired such as substantial exclusion of at least one solute, preferably a gas such as water vapor. As an example, an Army food tray can be made using at least one suitable high gas- barrier nanocomposite and preferably one of same to satisfy gas barrier requirements and create a superior product with a 3 -year food shelf- life. Other suitable manufactured articles have already been discussed and include those adopted to enclose a gaseous, liquid, solid or semi-solid material. More specific examples include beverage containers and blister packs.

0442Example 11- High-Strength Hytrel Nanocomposite As discussed in the U.S.S.N 60/139,481 provisional application, it is possible to make a wide variety of high-strength Hytrel nancompo sites. One such nanocomposite composition uses 10% by weight of ORMLAS organosilicate described in the Examples above mixed with molten black Hytrel 5612 in an extrusion screw. The resulting material was about 30 mil thick and about 7.5 inches wide. Upon testing the material showed a shore durometer of about 51-52, a tensile strength of about 142 kg/cm and an elongation of about 500%, providing a higher tensile strength without appreciable loss of elongation as compared to black Hytrel 5612.

0443The material thus provides high strength and barrier properties without decreasing elasticity.

0444Example 12- Polymer Alloy Nancomposites

0445Polyolefin-layered silicate polymer nanocomposite materials were made along lines discussed above. The following Table 13 provides ranges and examples of total weight percentage of various components used to make the materials.

0446TABLE 13 - Preparation of Six Polymer Alloy Nanocomposites

0447'Total Wt % Ex Ex Ex Ex Ex Ex Ex range 1 2 3 4 5 6 7

0448pp 40 - 99 70 75 40 40 50 66 97 pa .4 - 54 20 20 .8 .9 37 7 .9 fgpp .2 - 16 3 3 .2 .1 9 1 .1 oc 1 - 40 4 1 34 40 2 12 1 s.foc O - 25 3 1 25 19 2 14 1

04491. pp= polyolefin; pa= polyamide; fgpp= functionalized grafted polyolefin; oc= organoclay; s.foc= synthetically formulated organoclay All references disclosed in this application are incoφorated herein by reference.

0450While the invention has been described with reference to specific embodiments, modifications and variations of the invention may be constructed without departing from the scope of the invention, which is defined in the following claims.