Biomedical articles formed from polyparaffinsiloxanes

(24) Race day (62) Stamansokan number (11) Publication86-06-02 ^number 445 113

80-06-23

79-1 1-07 The application arrived as:

79-11-07 Swedish patent application (86) International filing day (86) Filing date for European patent application (30)

Q completed international patent application with number □ converted European patent application with number

79-02-22 US 14180 (71) Applicant Bausch k Lomb Incorporated, Rochester NY US (72) Inventor W G. Deichert, K. C. Su, M F. Vanburen, Macedon NY,

Arlington Tex, Chelmsford Mass (74) Representative AWAPATENT AB (54) Name Formed article of polyparaffin siloxane for biomedical use (56) Publications cited: - (57) Summary:

Monomers polyparaffin siloxanes, which are terminated with activated unsaturated groups, and polymers and copolymers thereof are described herein for use as contact lenses and biomedical devices with improved properties such as ability to transport oxygen, hydrolytic stability and they are biologically inert, transparent and have no use of filler. The polymer composite comprises a poly (organoparaffin siloxane) monomer which is α, ω-terminally linked by divalent hydrocarbon groups to polymerized radical polymerizable activated unsaturated groups.

The poly (organoparaffin siloxane) monomers used are represented by the formula:

<img file="SE445113B_D0001.tif" />

R - A which Sr is selected from a hydrocarbon group of 1 to about 12 carbon atoms and a carboxylic acid amide represented by the formula

DB 603415 in which A is an activated unsaturated group; R is a divalent hydrocarbon radical of 1 to about 22 carbon atoms; Rp Rp R_ and R. may be the same or different and are selected from

4 a monovalent hydrocarbon radical of 1 to about 12 carbon atoms and a halogen-substituted monovalent hydrocarbon radical having

1- about 12 carbon atoms; Rg and Rg may be the same or different and are selected from hydrogen, a hydrocarbon radical with

1- about 12 carbon atoms, a carboxylic acid group, a carboxylic acid ester group represented by the formula?

- C - O - R_? 9 which can be the same or different and each is selected from hydrogen and a hydrocarbon group having 1 to about 12 carbon atoms) x Hr 2 or greater and m Hr 1 or greater.

Consequently, contact lenses and biomedical devices, ie a shaped article, for use in biomedical applications can be hard or soft *. This hardness or softness is a function of the molecular weight of the monomer or monomers. Preferably, the contact lenses and biomedical devices are "soft *.

The copolymer compositions of the invention comprise the polymerisation product of the polyparaffin siloxane monomers and a monomer or monomers containing an activated vinyl group, polymers used to make biomedical devices and optical products, e.g. contact lenses, intraocular implants, etc.

7909196-3 ι

FORMATED ARTICLE OF POLYPARAFFINSILOXAN FOR BIOMEDICAL USE

The present invention relates to new polymer compositions and in particular to biomedical devices made therefrom. These devices include filler-free, oxygen transporting, hydrolytically stable, biologically inert, transparent, biomedical devices prepared from the polymerization of monomers represented by the formula

<img file="SE445113B_D0002.tif" />

in which A is an activated unsaturated group; R is divalent hydrocarbon radical having from 1 to about 22 carbon atoms; R ^, R.₂And can be the same or different and are selected from a monovalent hydrocarbon radical of 1-12 carbon atoms and a halogen-substituted monovalent hydrocarbon radical of 1 to about 12 carbon atoms; R. and R._rmay be the same or different and are selected

6 hydrogen, a hydrocarbon radical having from 1 to about 12 carbon atoms, a carboxylic acid group, a carboxylic acid ester group represented by the formula

O

II

- c - o - r_? is selected from a hydrocarbon group having from 1 to about 12 carbon atoms and a carboxylic acid amide represented by the formula

II - C -

<img file="SE445113B_D0003.tif" />

7909196-3 wherein Rg and Rg may be the same or different and each is selected from hydrogen and a hydrocarbon group having about 12 carbon atoms; x is 2 or greater and m is 1 or greater.

The invention relates in particular to polymers and / or copolymers comprising poly (organoparaffin siloxanes) which are terminally linked by divalent hydrocarbon groups to activated unsaturated groups copolymerized with monomers containing activated vinyl groups. The copolymers are optically clear and colorless. Polymers and copolymers described herein can conveniently be used for the manufacture of hard or soft contact lenses, intraocular implants as well as other prostheses, especially soft contact lenses.

BACKGROUND OF THE INVENTION

The use of siloxane polymers for the production of optical contact lenses and biomedical devices is desirable. This desirability is due to the high ability of polysiloxanes to transport oxygen and their generally relative softness. However, the tear strength and impact strength of polysiloxane elastomers are generally poor, and as a result fillers are used to increase the strength of the elastomers. In US Patents Nos. 3,996,187, 3,991,199, 3,341,490 and 3,228,741, contact lenses made from poly ( organosiloxanes) containing filler. The tear strength and impact strength of contact lenses made from the present polymer are sufficient, so no fillers are required.

US patents 3,996,187 and 3,996,189, as mentioned above, disclose contact lenses made from reinforced polysiloxanes. The lenses contain various polysiloxanes with similar refractive index as the silica filler, so that an optically clear silica-filled silicone elastomer can be formed from aryl and alkyl siloxanes. The material contains from 5 to 20% silica. The silica it was used, as mentioned, for its strength. The present invention contains no fillers for strength,

7909196-3 because the present material has sufficient strength without filler.

US Patent 3,341,490 discloses contact lenses made from mixtures of siloxane copolymers containing reinforcing silica filler. As mentioned, the contact lenses or biomedical devices of the present invention contain no fillers.

U.S. Patent 3,228,741 discloses contact lenses made of silicone rubber, particularly hydrocarbon-substituted polysiloxane rubber. This silicone material contains fillers such as pure silica to regulate the lenses' flexibility, flexibility and elasticity. The present polymers do not require any fillers.

U.S. Patent 3,808,178 discloses a polymeric material containing a polymethacrylate backbone having relatively short poly (organosiloxane) ester side chains on the backbone polymer. In this patent there is no cross-linking, since the monomers described in the patent are monofunctional, ie have only one functional group on each monomer. In order to provide crosslinking, this patent, column 5, teaches that different monomers having more than one functionality must be added for crosslinking. However, in the present invention, crosslinking is obtained since each siloxane mononium is difunctional, i.e., each monomer contains two functional groups, most preferably two methacrylate groups, resulting in crosslinking. In addition, contact lenses made from the polymers disclosed in U.S. Patent 3,808,178 would not transport oxygen sufficiently, however, contact lenses made from the present polymers would transport acid sufficiently to meet the requirements of the human cornea.

U.S. Patent 3,518,324 teaches vulcanization to make silicone rubber, in contrast, the present invention has to do with contact lenses made from polymerization of specific monomers.

7909196-3

US Patent 3,878,263 teaches a configuration that can be

<img file="SE445113B_D0004.tif" />

R can be hydrogen or monovalent hydrocarbon radicals having 1-12 carbon atoms.

R 'may be a monovalent hydrocarbon radical or a cyanoalkyl radical of 1-18 carbon atoms, R may be a divalent hydrocarbon radical of 1-18 carbon atoms, R' may be a radical selected from RCL and R '_OSi0_ _c. R "" is selected from hydrogen and monovalent hydrocarbon radicals.

c may be zero, but when c is zero, at least one Z must be OR.

Z is an important component because it is used for cross-linking of the chains. Z is a group selected from OR, R and OSiR₃ . Therefore, the monomers of the present invention are not taught in this patent.

US Patent 2,770,633 discloses 1,3-bis (4-methacryloxybutyl) tetramethyl disiloxane, one of the preferred monomers used in the present invention. This compound is taught in column 1, line 63 of said patent when R is vinyl. However, the patent teaches the monomer only, on the other hand, the present invention also teaches the polymer. In fact, this patent would not want the monomer to polymerize as it would not perform its function as a lubricant if polymerized.

US Patent 2,906,735 discloses a reaction between an alkylsiloxane and acrylic acid or a methacrylic acid which results in a disiloxane terminating with acrylate groups. Said patent does not disclose the polymers of the present invention.

7909196-3

U.S. Patent 2,922,807 discloses disiloxanes having acryloxy or methacryloxy groups attached to the silicone by a divalent alkylene radical of 2-4 carbon atoms.

U.S. Patent 3,763,081, as applicable, discloses the polymerization of an unsaturated siloxane, which is somewhat difficult to polymerize, since a double bond in this type of monomer is generally not particularly active. Both high temperatures and a peroxide catalyst or a platinum catalyst must be used to complete this type of reaction. See, for example, said patent column 4, lines 35-46. In the present reaction, it is specifically stated that the monomeric materials have activated unsaturated groups bound by a divalent hydrocarbon group to the siloxane, whereas, however, said patent has no activated unsaturated groups attached to the siloxane.

U.S. Patent 2,865,885 discloses, as applicable, a non-activated vinyl group, as shown in column 1, lines 25-30. The reason why the double bond in this patent is not active within the meaning of the present application is that the double bond is bound to either sulfur or oxygen. In the present invention, this same position would have one

II (-C-) carbonyl group. This would make the double bond active as defined in the present application. Since the reactivity ratios of U.S. Patent 2,865,885 are so different, i.e., the double bond is not active in this patent as defined in the present invention, it would be very difficult to obtain an acceptable copolymerization reaction using the formulas of this patent as compared to the active double bond of the present invention. invention, which is readily copolymerized.

In the present invention, the vinyl group is activated to facilitate radical polymerization. The formula given in column 2 865 885 in column 1, lines 25-30 is not suitable for radical polymerization, due to lack of

7909196-3 on resonance, but rather suitable for ion polymerization due to the polar nature of the substituents. Therefore, it would be extremely difficult, if possible, for this patent to form the compounds of the present invention. In addition, the compounds formed in this patent are not hydrolytically stable, due to the presence of the silicon-nitrogen bond in the formula. The present invention cannot utilize a hydrolytically unstable compound. In addition, the products of this hydrolysis in said patent could be harmful to the human eye, especially the amines. Also in column 3 of this patent, the link is an amine link to the double bond and in the present invention this link is always an alkyl. Therefore, US Patent 2,865,885 does not teach the existing monomers.

U.S. Patent 2,793,223, as applicable, in Example 5, column 3, lines 30-41, states that a phenyl group is attached to the siloxane. That material would be very hard. In addition, contact lenses made from the polymers, which in turn are made from the monomers described in this patent - due to the presence of the phenyl group on the siloxane as shown in Example 5 of this patent - would not sufficiently transport oxygen, whereas contact lenses made from existing polymers would transport oxygen sufficiently to meet the requirements of the human cornea.

Katz and Zewi, Correlations Between Molecular Structure and Some Bulk Properties of Highly Cross-linked Polysiloxanes, J. Polymer Sci., Vol. 46, pp. 139-148 (1974), state, where appropriate, that divinyl monomers can be prepared by esterification of the carboxyl terminated the compounds with two molecules of a monoester of ethylene glycol and acrylic acid. The polymerization can be carried out by ultraviolet radiation at room temperature. In addition, in this article by Katz et al, the structure is stated on page 146. If this formula is broken in consideration of the material of the present invention.

7909196-3 the formula would be as follows:

<img file="SE445113B_D0005.tif" />

<img file="SE445113B_D0006.tif" />

C = 0 I

<img file="SE445113B_D0007.tif" />

In the above formula, the group R has an ester linkage, whereas R is a hydrocarbon group in the present material.

In the above formula, the centrally repeated unit is a dimethylsiloxane unit, whereas the centrally repeated unit of the present material is a repeated unit of a paraffin siloxane as illustrated.

7909196-3 below. The R-coupling in the Katz et al article is not as hydrolytically stable as the hydrocarbon coupling in the present polymer. The ester coupling in Katz et al can be hydrolyzed. This stability is important if this material is to be used in soft contact lenses or biomedical devices, as these types of devices are usually heated for disinfection. If the contact lens loses its shape, it loses its optics. It is to be understood that the present material does not have an ester coupling. However, this coupling is between groups A and R. It is, in fact, in group A as shown below with one formula of one of the most preferred embodiments of the invention.

7909196-3

<img file="SE445113B_D0008.tif" />

<img file="SE445113B_D0009.tif" />

CH_O-Si-CH

CH

<img file="SE445113B_D0010.tif" />

<img file="SE445113B_D0011.tif" />

<img file="SE445113B_D0012.tif" />

CH

First-.....- J. 1

This Katz et al reference teaches, in addition to the specific formula on page 146, only that phase differences are detectable as the siloxane chain length decreases. When

7909196-3 As the siloxane chain length increases, Katz et al state that the phase differences are lost and these differences amount to a continuous transition.

In addition to the above, it is important to note that Katz et al do not suggest any use for this material ·.

Katz and Zewi Some Rheological Properties of Highly Crosslinked Polysiloxanes J. Polymer Sci. vol. 13, pp. 645-658 (1975), as applicable, discloses the same material as in the above reference, (1974) the article by Katz et al. This article teaches in more detail the steps necessary to prepare the polymer starting materials according to the 1974 article. Katz et al, in this article, teach, where applicable, how to synthesize the carboxyl terminated siloxane. This is illustrated on pages 646-647. Katz et al then cross-link this using a different chemical reaction than in the present invention to prepare the polymer shown on page 649. This polymer is in no way related to the present materials. In addition to the above, it is important to note that this Katz et al reference does not mention any use of the material.

Katz and Zewi Microheterogeneity in Crosslinked Polysiloxane J. Polymer Sci. Polymer Chemistry Edison, vol. 16, pp. 597-614 (March 1978) teaches, as appropriate, the same material as set forth in the aforementioned (1974) and (1975) articles by Katz et al. The only new material mentioned is on page 598, line 8, ie cross-linked polyesters. These crosslinked polyesters are not relevant to the present invention. Katz et al, in this article, teach, where applicable, how to produce certain monomers. Katz et al only state the same cross-linked material as he suggested in his earlier (1974) and (1975) articles. Katz et al then discuss the physical properties and microheterogeneity of these crosslinked polymers.

He discusses the differences in the phase separation on a submicroscopic scale. Regarding the physical properties mentioned by Katz et al in his article on page 597,

7909196-3

II he discusses the physical properties of polysiloxanes in general. Katz et al describe specific properties of their polymers on page 609, where he presents module temperature data. He then describes cross-linking efficiency on page 607. He measures properties that give him an idea of ​​his cross-linking efficiency. It should again be mentioned that Katz et al in his (1978) article do not mention more materials than he stated in his previous articles, except for the description of the cross-linked polyesters on page 598.

However, these materials are not relevant to the present invention. In addition to the above, it is important to note that this Katz reference also does not mention any use of this material, except as possible sealants.

WA Piccoli, GG Haberland and RL Merker, J. Am. Chem. Soc. Highly Strained Cyclic Paraffin Siloxanes Vol 82, pages 1883-1885 (April 20, 1960) teach, as appropriate, the preparation of the cyclic paraffin siloxane monomers that can be used in the present invention to prepare the prepolymers of the present invention. These prepolymers, i.e. linear monomers, in the present invention are then cross-linked to form the polymers used to make contact lenses. On page 1884, column 2, lines 15-27 of said article, it is stated that these cyclic paraffin siloxane monomers can be polymerized using strong acids or bases to form linear polymers. The linear polymers, as mentioned, are used in the present invention as prepolymers and crosslinked to form contact lens preparation materials. At some point in this article, the cross-linked polymers of the present invention are described or proposed. Nor does this article suggest or describe that the polymers can be used to make contact lenses.

RL Merker and MJ Scott J. of Polymer Sci., The Copolymerization of Cyclic Siloxanes Vol. 43,

7909196-3 pages 297-310 (1960) teach, as appropriate, copolymerization studies using cyclic alkylsiloxanes. These materials are copolymerized with silylene siloxane and then polymerization rates are determined. The silylene siloxane is used because it has no equilibrium with the annular and linear form. Once the ring mold is opened, the ring remains open, ie the reaction proceeds in one direction. The crosslinked polymers of the present invention are neither proposed nor taught in this article, nor is the use of these polymers proposed or taught as contact lenses.

US patents 3,041,362 and 3,041,363 teach, as applicable, the same material as set forth in the aforementioned Articles J. Am. Chem. Soc. and J. of Polymer Sci. where 15 Marks is one of the authors. However, it is also stated that some polyfunctional siloxanes can be used with the monomers to yield crosslinked polymers and copolymers. The crosslinked polymers used in the present invention are neither taught nor proposed in these references, nor are^! the polymers listed in these references are ever relevant to the present polymers. In addition, these references do not suggest or teach that these polymers could be used as contact lenses.

Ε. E. Bostick, Kinetics and Mechanisms of Polymerization, Vol 2. (1969) Frisch and Regan, ed. Chapter 8 Cyclic Siloxanes and Silazanes pages 343-357, teaches, as appropriate, siloxane polymerization using cyclic siloxanes. This article teaches nothing beyond what is stated in the above article by J. of Polymer Sci. by RL Merker and MJ Scott.

Ε. Ξ. Bostick, Chemical Reactions of Polymers, High Polymers series vol-19 (1964) EM Fettes, ed. Chapter 7 Interchange Reactions section B Silicones page 525 teaches, as appropriate, siloxane copolymerization using cyclic siloxanes. In addition, it is stated that these reactions proceed in one direction. This article teaches nothing beyond what is described in the above

7909196-3 article by J. of Polymer Sci. by RL Merker and MJ Scott.

None of the above-mentioned patents or publications teach the present invention and even less the preferred reactions of the present invention. In addition, it is extremely important that no prior publication in the art teach new contact lenses or biomedical devices of the present invention made from the present polymers. SUMMARY OF THE INVENTION

The present invention provides materials which can advantageously be used for the manufacture of prostheses, such as heart valves, intraocular lenses and contact lenses.

In one embodiment of this invention, there is provided a filler-free, oxygen-transporting, hydrolytically stable, biologically inert, transparent shaped article for use in biomedical applications including contact lenses comprising a crosslinked polymer made from poly (organoparaffin siloxane) monomers represented by the following formula:

<img file="SE445113B_D0013.tif" />

in which A is an activated unsaturated group; R is a divalent hydrocarbon radical of 1 to about 22 carbon atoms; Rj, R₂R 1 and R 2 may be the same or different and are selected from a monovalent hydrocarbon radical of 1 to about 12 carbon atoms and a halogen-substituted monovalent hydrocarbon radical of 1 to 12 carbon atoms; Rg and Rg may be the same or different and are selected from hydrogen, a hydrocarbon radical having from 1 to about 12 carbon atoms, a carboxylic acid group, a carboxylic acid ester group represented by the formula

7909196-3

II

- C - 0 - R_? is selected from a hydrocarbon group having 1 to about carbon atoms and a carboxylic acid amide represented by the formula

<img file="SE445113B_D0014.tif" />

wherein R R and R R may be the same or different and each is selected from hydrogen and a hydrocarbon group having from about 1 to about

12th carbon atoms; x is 2 or greater and m is 1 or greater.

When the terms activated or radical polymerizably activated, the term unsaturated groups is used¹Here, it is meant that an unsaturated group which is activated is one which has a substituent which promotes radical polymerization. These activated unsaturated groups are polymerized to form the polymers of the present invention. Preferably, the activation groups used herein are suitable for polymerization under mild conditions, such as ambient temperatures.

When a poly (organoparaffin siloxane) monomer which is α, ω-terminally bonded by divalent hydrocarbon groups to polymerized radical polymerizably activated unsaturated groups is designated, methylene or propylene, etc., and then attached to each end of this compound is an activated unsaturated group, such as methacryloxy, etc., and this is then the most preferred monomer. When the monomers are polymerized, i.e. cross-linked, the activated unsaturated groups are polymerized. Thereafter, the monomers form three-dimensional polymers or copolymers, which are the materials of which the biomedical devices, including conical lenses, are made.

As a result of the presence of the activated unsaturated groups, the monomers used in accordance with this invention are readily polymerized to form three-dimensional polymeric networks which permit transport of oxygen and are optically clear, strong and can be made soft or hard as required.

Where the term monomer is used herein, it is intended to include polyparaffin siloxanes terminated with polymerizable unsaturated groups. The method of prolonging the monomer's paraffin silox fraction is indicated herein as siloxane ring insert. The chain length of the monomer's poly (paraffin oxide) center unit can be as high as 800 or more.

When the term polymerization is used herein is meant the polymerization of the double bonds in the polyparaffin siloxanes terminated with polymerizable unsaturated groups resulting in a cross-linked three-dimensional polymeric network.

The relative hardness (or softness) of the contact lenses, i.e. the polymers of the invention, can be varied by decreasing or increasing the molecular weight of the monomeric poly (organoparaffin siloxane) terminated with the activated unsaturated groups or by varying the percentage and type of comonomer. As the ratio of organoparaffin siloxane units to the terminating units increases, so does the softness of the material. Conversely, as this ratio decreases, the stiffness and hardness of the material decrease.

More preferably, a filler-free, oxygen-transporting, flexible, hydrolytically stable, biologically inert, transparent, elastic, soft, polymer-shaped article is provided for use in biomedical applications including contact lenses comprising a poly (organoparaffin siloxane) made of a poly (organoparafin finsiloxane) monomer represented by the following formula:

7909196-3

<img file="SE445113B_D0015.tif" />

in which A is an activated unsaturated group; R is a divalent hydrocarbon radical of 1 to about 22 carbon atoms; R ^, R.₂, Rg and R kan may be the same or different and are selected from a monovalent hydrocarbon radical of 1 to about 12 atoms and a halogenated substituted monovalent hydrocarbon radical of 1- to 12 carbon atoms; R₅ and R 9 may be the same or different and are selected from hydrogen, a hydrocarbon radical having from 1 to about 12 carbon atoms, a carboxylic acid group, a carboxylic acid ester group represented by the formula

II

- C - 0 - R_? in which R? is selected from a hydrocarbon group having from 1 to about 12 carbon atoms and a carboxylic acid moiety represented by the formula

<img file="SE445113B_D0016.tif" />

<img file="SE445113B_D0017.tif" />

<img file="SE445113B_D0018.tif" />

wherein Rg and Rg may be the same or different and each is selected from hydrogen and a hydrocarbon group having from 1 to about 12 carbon atoms; x is 2 or greater and m is 1 or greater. A contact lens can be formed from the above material by centrifugal casting, if desired, as taught in U.S. Patent 3,408,429.

In another embodiment of this invention, materials which are polymerizable and comprising a poly (organoparaffin siloxane) monomer represented

7909196-3 of the formula

<img file="SE445113B_D0019.tif" />

in which A is an activated unsaturated group; R is a divalent hydrocarbon radical of 1 to about 22 carbon atoms; R ^, R.₂, R 2 and R 2 may be the same or different and are selected from a monovalent hydrocarbon radical of 1 to about 12 carbon atoms and a halogen-substituted monovalent hydrocarbon radical of 1 to about 12 carbon atoms; R_r and R, may be the same or

6 different and are selected from hydrogen, a hydrocarbon radical with

1 to about 12 carbon atoms, a carboxylic acid group, a carboxylic acid ester group represented by the formula

IN)

- C - 0 - R_? in which R_y is selected from a hydrocarbon group of 1 to about 12 carbon atoms and a carboxylic acid amide represented by the formula

<img file="SE445113B_D0020.tif" />

in which R_O and R_n may be the same or different and each of them is selected from hydrogen and a hydrocarbon group having 1 to about carbon atoms; x is 2 or greater and m is 1 or greater, copolymerized with one or more monomers which may be one of lower esters of acrylic or methacrylic acid, styryls, allyls or vinyls forming a copolymer in a crosslinked network. The copolymers are in the form of clear, three-dimensional networks.

7909196-3 strong and suitably can be used to provide films and shaped bodies, such as contact lenses.

The novel copolymers of the invention may comprise 10-90 parts by weight of one or more of the monoparaffin siloxanes monomers described herein and 90-10 parts by weight of the polymerizable monomers. The preferred biomedical devices, including contact lenses formed from these copolymers, are filler-free, oxygen transporting, flexible, hydrolytically stable, biologically inert, transparent, elastic and soft.

The three-dimensional network polymer products of the invention are readily prepared by conventional radical polymerization techniques. The monomers of organosiloxane alone or in the presence of comonomers together with about 0.05 to about 4% by weight, preferably 0.05-2% by weight of a radical initiator can be heated to a temperature of about 30 ° C to about 100 ° C to initiate and complete the polymerization. The polymerizable monomers, i.e., the poly (organoparaffin siloxanes), with or without comonomers, can preferably be subjected to UV light irradiation in the presence of suitable activators, such as benzoin, acetophenone, benzophenone and the like, for a sufficiently long period of time to form a three-hour period. polymer network.

The polymerization can be carried out directly in contact lens molds or can be molded into sheets, rods or sheets, which can then be machined to a desired shape. Preferably, the polymerization is carried out while the material is centrifugal cast, as taught in U.S. Patent 3,408,429.

It is well known that the ability of polysiloxanes to transport oxygen is substantially greater than that of conventional contact lens polymers such as polymethylmethacrylate (PMMA) or polyhydroxyethylmethacrylate (PHEMA). The ability to transport oxygen to the materials of the invention can be varied by changing the percentage of siloxane units. For example, a higher percentage of siloxane units results in a product having greater ability to transport oxygen compared to a lower percentage of siloxane units which results in a material with less ability to carry oxygen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with one embodiment of this invention, shaped articles are provided for use in biomedical applications, including contact lenses, ♦.

which are prepared from three-dimensional polymeric network polymers (organoparaffin siloxands) which are α, ω-terminally linked by divalent hydrocarbon groups to polymerized radical polymerizably activated, unsaturated groups which form polymers in a crosslinked network. The poly (organoparaffin siloxanes), i.e. the monomers used, have the formula:

<img file="SE445113B_D0021.tif" />

in which A is an activated unsaturated group; R is a divalent hydrocarbon radical of 1 to about 22 carbon atoms; R ^, R ^, R ^ and R, may be the same or different and are selected from a monovalent hydrocarbon radical of 1 to about 12 carbon atoms and a halogen-substituted monovalent hydrocarbon radical of 1 to about 12 carbon atoms; Rg and Rg may be the same or different and are selected from hydrogen, a hydrocarbon radical having from 1 to about 12 carbon atoms, a carboxylic acid group, a carboxylic acid ester group represented by the formula

Jl

- C - 0 - R_?

7909196-3 in which R? is selected from a hydrocarbon group having 1 to about carbon atoms and a carboxylic acid amide represented by the formula

<img file="SE445113B_D0022.tif" />

<img file="SE445113B_D0023.tif" />

which Rg and Rg may be the same or different and each is selected from hydrogen and a hydrocarbon group having 1 to about 12 carbon atoms; x is 2 or greater and m is 1 or greater.

m may suitably be in the range of 50 to about 200. However, the range of m may be greater such as preferably 50 to 800. however, m may be greater than 800. If it is desired to obtain a hard contact lens, m should be less than 25.

x is preferably 2 to 10 and most preferably 3.

When the term soft is used herein to describe the biomedical devices of the invention including contact lenses, it is meant that in the above formula, after polymerization, it is greater than 25, preferably from about 50 to about 800.

When the term hard is used herein to describe the contact lenses or biomedical devices of the present invention, it is meant that the above formula, after polymerization, is less than 25.

Preferably, A is one of

- cyanoacryloxy

II ch₂ = C - C - 0 G s N acrylonitrile

<img file="SE445113B_D0024.tif" />

7909196-3

J * acrylamido

CH₂ = CH -

<img file="SE445113B_D0025.tif" />

- NH acryloxy

CH₂ = CH - C - 0 methacryloxy

OI

CH- = C - C - 0 ² I ch₃ styryl

<img file="SE445113B_D0026.tif" />

and

N - vinyl - 2 - pyrrolidinone - X - yl where x can be 3, 4 or 5 p

CH₂ /^CH2 CH- = CH - N ^XC - ao

More preferably, A is acryloxy or methacryloxy. However, thinner groups containing activated unsaturation can be used with ease and such groups are well known to those skilled in the art. Most preferred is A methacryloxy or acrylamido. Preferably, R may be an alkylene radical. Therefore, R is preferably methylene, propylene, butylene, pentamethylene, hexamethylene, octamethylene, dodecylmethylene, hexadecylmethylene or octadecylmethylene; arylene radicals such as phenylene, biphenylene or the corresponding alkylene and arylene radicals. More preferably, R is an alkylene radical of about 1, 3 or 4

7909196-3 carbon atoms. Most preferably, R is an alkylene radical having from about 3 to 4 carbon atoms, for example, butylene. Preferably, R ^, R R₂, R₃ and -R ^ alkyl radicals having 1-12 carbon atoms, for example methyl, ethyl, propyl, butyl, octyl, dodecyl and the like; cycloalkyl radicals, for example cyclopentyl, cyclohexyl, cycloheptyl and the like; mononuclear and binuclear aryl radicals, for example benzyl, phenylethyl, phenylpropyl, phenylbutyl and the like; alkaryl radicals, for example, tolyl, xylyl, ethylphenyl and the like; halogenary radicals such as chlorophenyl, tetrachlorophenyl, difluorophenyl and the like; halogen substituted lower alkyl radicals with up to about four alkyl carbon atoms such as floromethyl and floropropyl. More preferably, R₂R 2 and R 2 are methyl radicals and phenyl radicals, and most preferably R₂, R 3 and R 3 methyl radicals.

Preferably, Rg and Rg are selected from hydrogen, a hydrocarbon having from 1 to about 6 carbon atoms and a carboxylic acid group. More preferably, R 9 and R 9 are selected from hydrogen and methyl.

R? is preferably a hydrocarbon group having 1 to about 6 carbon atoms. Most preferred is R ·? methyl.

Preferably, Rg and Rg are selected from hydrogen and a hydrocarbon having 1 to about 4 carbon atoms. Most preferably, Rg and Rg are selected from hydrogen and methyl.

The polyparaffin siloxanes terminated with unsaturated groups, i.e., the monomers used in the present invention can be prepared by equilibrating the appropriately substituted disiloxane, e.g. et al., J. Am. Chem. Soc., Highly Strained Cyclic Paraffin-Siloxanes Vol 82, pages 1883-1885 (April 20, 1960). The degree of softness, physical properties, such as tensile strength, modulus and relative elongation, determine the amount of cyclic organoparaffin siloxane which is equilibrated with the disiloxane. By increasing the amount of cyclic paraffin siloxane, the value of m is increased.

7909196-3

Although the reaction between a cyclic paraffin siloxane and disiloxanes has not been specifically described for the disiloxanes used in the present invention to provide the activated unsaturated groups as terminating groups for the polyparaffin siloxanes, it is a conventional reaction and has been described, for example, in Merker US Patent 3,011,362 from 1962 , and this reference is incorporated herein by reference.

The following reactions represent the most preferred materials of the present invention. 1,3-bis (hydroxyalkyl) tetramethyl disiloxane dimethacrylates are prepared as follows: (1) esterification with acryloyl or methacryloyl chloride or anhydride. For example, the following is with methacryloyl chloride:

HO ά CH₂ hrs

<img file="SE445113B_D0027.tif" />

<img file="SE445113B_D0028.tif" />

CH

IN ^{2 3}

- Si CH₂ hrs_n OH ch₃

Preferably, n = 1, 3 or 4

Most preferred is n = 3 or 4

CH, 0

IN ³ II,

CH₂ = C - C - Cl

CH, 0 V CH, CH, 0 CH,

IN ³ II I ³ IN ³ III ³

C - C - 0 -fCH₂&gt;_n Si - 0 - Si &lt;CH₂t_nO - C - C

CH₂ CH₃ CH₃CH

Preferably, n = 1, 3 or 4

Most preferred is n = 3 or 4 (2) Another most preferred method of preparation

1,3-bis (hydroxyalkyl) tetramethyl disiloxane dimethacrylates are by transesterification with methyl methacrylate

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<img file="SE445113B_D0029.tif" />

Then, the paraffin siloxane groups between the two methacrylate ignition groups can be inserted by a ring opening insertion reaction with 1,1,3,3-tetramethyl-1,3-disila-2-oxacyclopentane as follows:

CH_ O CH- CH_ AND,

I 3 || i 3₍ 3 | l | 3

CH₂ = C - C - O -f CH₂ åi - O - Si f CH₂ &gt;_n 0 -C - C = CH₂^CH3^3

<img file="SE445113B_D0030.tif" />

Preferably, n = 1, 3 or 4

Most preferred is n = 3 or 4

Preferably, m = 50 to 800

Most preferred is x = 2 to 3 (crosslinking / polymerization)

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<img file="SE445113B_D0031.tif" />

<img file="SE445113B_D0032.tif" />

<img file="SE445113B_D0033.tif" />

<img file="SE445113B_D0034.tif" />

<img file="SE445113B_D0035.tif" />

(three-dimensional network)

<img file="SE445113B_D0036.tif" />

I.

im KO

0=0

I o

Preferably, n = 1, 3 or 4. Most preferably, n = 3 or 4.

Preferably, m = 50 to 800. Most preferably, x = 2 to 3.

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The poly (organoparaffin siloxanes) made from the monomers of the invention are usually clear, colorless liquids whose viscosity depends on the value of m. These monomers can be easily cured to molds by conventional methods such as UV polymerization, or by the use of radical initiators plus heat. Illustrative radical initiators which may be used are bis (isopropyl) peroxide bicarbonate, azobisisobutyronitrile, acetyl peroxide, lauroyl peroxide, decanoyl peroxide, benzoyl peroxide, tertiarybutyl peroxypivalate and the like.

To further control the properties of the polymers of the present invention, a mixture of the monomers comprising low value monomers and high value monomers can be polymerized. When m has a low value, ie below 25, the resulting contact lenses or biomedical devices, i.e., the polymers, are relatively hard, oxygen transporting, hydrolytically stable, biologically inert, transparent and do not require fillers to improve the mechanical properties. The monomers have a relatively low molecular weight and, as a result, the viscosity is low enough, for example, about 3 cSt, so that the lenses can be easily prepared by centrifugal casting. When m has a relatively high value, i.e., above 25, the resulting contact lenses or biomedical devices, i.e., the polymers, are relatively soft, oxygen transporting, flexible, hydrolytically stable, biologically inert, transparent, elastic and require no fillers for enhancement of the mechanical properties. properties. The monomers should preferably have a molecular weight sufficiently low such that the viscosity is low enough for centrifugal casting of the monomers, e.g., about 175 St or less, as measured in Gardner viscosity tubes. Preferably, m is about 50 to 800.

In accordance with another embodiment of this invention, polymers of monomers which are poly (organoparaffin siloxane) are terminally bonded through divalent hydrocarbon groups to activated unsaturated groups.

7909196-3 copolymerized with monomers containing an activated vinyl group.

The comonomer can be any polymerizable monomer that readily polymerizes by radical polymerization and is preferably a monomer containing an activated vinyl group. The addition of comonomers can enhance particularly desirable properties. For example, buttons made from copolymers of the present monomers of poly (the paraffin siloxanes) and tetrahydrofurfuryl methacrylate can be more easily turned into contact lenses than buttons, i.e., polymers made from monomeric poly (paraffin siloxanes only). The wettability of contact lenses, i.e. polymers, made from poly (the paraffin siloxanes) can be substantially increased by copolymerizing the present monomers with N-vinylpyrrolidone.

Illustrative comonomers which may be conveniently used in accordance with the present invention are:

Derivatives of methacrylic acid, acrylic acid, itaconic acid and crotonic acid such as:

• methyl, ethyl, propyl, isopropyl, n-butyl, isobornyl, mentyl, adamantanyl, isopinocamphyl, hexyl, heptyl, aryl, allyl, cyclohexyl, 2-hydroxyethyl, 2- or 3-hydroxypropyl and butoxyethyl methacrylates; and propyl, isopropyl, butyl, isobornyl, mentyl, adamantanyl, isopinocamphyl, hexyl, 2-ethylhexyl, heptyl and aryl acrylates; and propyl, isopropyl, butyl, hexyl, 2-ethylhexyl, heptyl and aryl itaconates; and propyl, isopropyl, butyl, hexyl, 2-ethylhexyl, heptyl and aryl crotonates.

Also mono- or diesters of the above-mentioned acids with polyethers of the following formula may be used:

HO^(Cn^hrs2n^{0) q H} wherein n is an integer of 1 to about 12, preferably 2 or 3, and q is an integer of 2 to about 6, preferably 2 to 3.

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Other comonomers may include: styryls such as tertiary butylstyrene, propylstyrene, styrene, divinylbenzene, vinylethylbenzene, vinyltoluene, etc.

Allyl monomers such as diallyl diglycol dicarbonate, allyl cyanide, allyl chloride, diallyl phthalate, allyl bromide, diallyl fumarate and diallyl carbonate can be used.

Nitrogen-containing monomers can also be used such as:

n-vinylpyrrolidone, 3-oxybutylacrylamide, etc.

The lower the value of m in the formula for the present monomers, the more compatible the monomers are with the above comonomers.

The advantages of using the biomedical devices, especially the contact lenses, i.e. the polymers, of the present invention, which are made from the monomers described herein, are numerous. As an example, (1) the advantages of using activated vinyl end groups to cure the paraffin siloxane material are (a) that the high reactivity systems allow rapid cure at room temperature if appropriate initiators are used. Room temperatures are preferred. This is desirable because the preferred way of molding the contact lenses is centrifugal casting. (b) No filler is required to provide suitable physical strength as is common with most silicone resins. This is desirable as the use of fillers requires that other potentially undesirable materials be added to the composition to correct the refractive index of the contact lenses. (2) In addition, the biomedical devices made from the polymers of the present invention are oxygen transporting. This is important if the material is to be used for contact lenses. The human cornea requires about 2 x 10 cm / (cm cm of oxygen) through the contact lenses, as reported by Hill and Fatt, American Journal of Optometry and Archives of the American Academy of Optometry, vol. 47, p. 50 ( 1970). When m is at least about 4, the paraffin siloxane chain is sufficient

7909196-3 long in the present composition to exceed the ability of the cornea and other living tissues to carry oxygen. However, in specific situations, ra may be as low as 1. Depending on the unique properties of the contact lenses or biomedical devices, i.e. the polymers, according to the invention, m may be large enough to allow adequate transport of oxygen and at the same time retain its desirable properties in terms of extensibility, tear strength, flexibility, elasticity and softness.

When the term ability to transport oxygen or oxygen transport is used in the present invention, it is intended that the material permits sufficient transfer of oxygen by itself to provide the required oxygen of the human cornea and other living tissues. The oxygen requirements of the human cornea are -6 3 2 as mentioned about 2 x 10 cm / (cm cm atm). The ability to transport oxygen was determined by a special test procedure described in conjunction with the following Example III. (3) These lenses and biomedical devices are hydrolytically stable, which means that when the contact lenses or devices are placed in an aqueous solution, ie in the eye, or during the disinfection stage, i.e. water plus heat, the lenses or devices will not change in chemical composition, i.e., hydrolyzing and causing the lenses or devices to change shape, which would result in an undesirable change of optics or shape.

(4) The more preferred contact lenses or biomedical devices according to the invention are also elastic. When the term elastic is used herein, it is intended that the lenses or biomedical devices quickly regain their original shapes after they have been deformed.

(5) The lenses are preferably manufactured by centrifugal casting, for example, by the method described in US Patent 3,408,429. Monomers having too high viscosity cannot be centrifugal casted. In general, however, the higher the molecular weight of the monomers, the longer it is

7909196-3 chain length, i.e., the greater the value of m, and as a result, the properties are the more desirable for the preferred contact lenses, i.e. the polymers, of the present invention made from these monomers. The lower the chain length and the higher the molecular weight, the higher the viscosity of the monomers. However, if centrifugal casting is to be used, the viscosity of the monomers must be such that these materials can be centrifugal casted. The monomers of the present invention may have sufficiently high molecular weights to give all the desirable properties when polymerized, but low enough to be centrifugal cast while still in the monomeric form. The preferred weight average value for the molecular weight is from about 4000 to 60,000 for the monomers of the invention. (6) The most preferred contact lenses or biomedical devices according to the invention should be soft. By using the term soft in the present invention, in the preferred embodiment, it is intended that the lenses or devices should have a Shore hardness of about 60 or below on the scale A. (7) The preferred contact lenses or biomedical devices of the invention should be flexible. When the term flexible is used herein, it is intended that the contact lenses or biomedical devices may be folded or bent backward relative to themselves without being broken.

The most preferred contact lens or biomedical device according to the invention is a filler free, oxygen transporting, flexible, hydrolytically stable, biologically inert, transparent, elastic, soft, polymeric contact lens or shaped article for use in biomedical applications and comprises a poly (organoparaffin siloxane) monomer which is α , ω-terminally bound by divalent hydrocarbon groups to polymerized radical polymerizable activated unsaturated groups. The poly (organoparaffin siloxane) monomer used to prepare the polymer from which the contact lenses

7909196-3 or biomedical devices, in turn, have the preferred formula

<img file="SE445113B_D0037.tif" />

wherein A is selected from methacryloxy and acryloxy; R is an alkylene radical of 3-4 carbon atoms; R ^, R.₂, R 1 and R 2 may be the same or different and are monovalent hydrocarbon radicals having 1 to about 12 carbon atoms; Rg and Rg are hydrogen atoms; x is 2 or 3 and m is 50 to 800.

The most preferred contact lenses or biomedical devices, i.e., the polymers of the invention are, as mentioned, filler-free, have an oxygen transport rate of at least about 2 x 10 cm / (s.cm atm), are hydrolytically stable, biologically inert, transparent, elastic. and has a softness preferably of about 60 or less on the Shore Hardness Scale A. Most preferably, the Shore Hardness should be 25 to 35 on the Scale A.

To further elucidate the physical properties of the most preferred contact lenses or biomedical devices according to the invention, the stretch modulus of elasticity should be about 400 g / mm or less.

When the material is to be used as contact lenses, the Shore hardness and module can be related to the wearer's comfort for the wearer when applied to the human eye.

Another advantage of the preferred embodiment, i.e. soft contact lenses, of the invention is that lenses made of the polymers of the present invention can be made large enough to cover the entire cornea of ​​the eye, resulting in greater comfort. Hard contact lenses, such as PMMA lenses, have to be made smaller due to their poor ability to transport

7909196-3 acid. In addition, the larger the lenses, the easier it is to locate the optical center of the lenses. The larger the lens, the easier it is to maintain the optical axis required when manufacturing special lenses for people with special vision problems, for example, for people with astigmatism. Another advantage of the preferred soft lenses of the invention is that the present preferred soft lenses have a softness similar to that of HEMA lenses, but are, more importantly, more oxygen permeable, i.e., have the ability to transport more acid. HEMA lenses are not oxygen permeable or do not have the ability to transport oxygen to the degree necessary to meet all the requirements of the human cornea.

When the word oxygen permeable is used herein, it is intended that the present biomedical polysiloxane material carries oxygen at a rate of at least about 2 x 10^-6 cm³/ (s. crn ^ atm).

Although the polyparaffin siloxanes of the present invention can be used to make contact lenses, these polymers and copolymers mentioned may also be used for other uses, such as shaped articles for use in biomedical applications. These polymers and copolymers can be used to produce biomedical devices, such as shaped articles, such as dialysis apparatus diaphragms, for the production of artificial kidneys and other biomedical implants as disclosed in Wichterle, US Patent 2,976,576 and Wichterle, US Patent 3,220,960. the polymers and copolymers can be used in the preparation of therapeutic dressings as described in Shephard, U.S. Patent No. 3,428,043. The present polymers and copolymers can also be used in the manufacture of medical surgical devices, such as heart valves, vasculature, intrauterine devices, membranes and other films, dialysis apparatus, catheters, dental scaffolds and other such devices as disclosed in Shephard U.S. Patent 3,520,949. 618 231.

7909196-3

The present polymers and copolymers can be used to modify collagen to make blood vessels, bladders and other such devices as described in Kliment US Patent 3,563,925. The present polymers and copolymers can be used to make catheters as described in Shephard US Patent 3,566,874. The present polymers and copolymers can be used as semipermeable sheets for dialysis, artificial tooth rows and all such things as described in Stoy US Patent 3,607,848. The present polymers and copolymers can be used to make leather breathable and other materials described in Shephard US Patent 3,660,218. The present polymers and copolymers can be used in ophthalmic dentures and all other uses described in Wichterle US Patent 3,679,504. The present copolymers and polymers can be used in the manufacture of printing plates and for other uses of the same type as described in Takaishi US Patent 3,733,200.

When the terms shaped article for use in biomedical applications or "biomedical devices are used herein, it is considered that the materials described herein have physicochemical properties which make them suitable for prolonged contact with living tissue, blood and mucosa, which should be required by biomedical shaped articles, such as surgical implants, blood dialysis devices, blood vessels, artificial ureters, artificial breast tissue and membranes designed to come into contact with body fluid outside the body, such as kidney dialysis and heart / lung machinery membranes, and the like. It is known, for example, that blood is quickly damaged in contact with artificial surfaces. The design of a synthetic surface that is antithrombotic and non-hemolytic to blood is necessary for prostheses and devices used with blood. The present polymers and copolymers are compatible with living tissue.

7909196-3

The present polymers and copolymers described herein can be boiled and / or autoclaved in water without being damaged, thereby providing sterilization. Thus, an article formed from the present polymers and copolymers can be used in surgery, where an article compatible with living tissue or with the mucosa can be used.

The following examples are illustrative only and should in no way be considered to limit the invention. All parts and percentages given herein are by weight and all viscosities are measured at 25 ° C unless otherwise specifically stated.

EXAMPLE I

557 1,3-bis (4-hydroxybutyl) tetramethyldisiloxane,

634 g of dry pyridine and 2 liters of hexane were charged to a liter of reaction flask, which was equipped with a mechanical stirrer and a drying tube. The mixture was cooled to 0 ° C and then 836 g of methacryloyl chloride was added dropwise. The mixture was stirred continuously overnight. The reaction solution was successively extracted with 10% aqueous HCl and NH och solutions to remove excess reagent and pyridine hydrochloride. The resulting solution of the product in hexane was dried over anhydrous MgSO 4, filtered and the solvent removed under reduced pressure. Approximately 459 g (55% yield) of 1,3-bis (4-methacryloxybutyl) tetramethyl disiloxane was collected. The structure was confirmed by infrared spectrum, proton magnetic resonance spectrum and elemental analysis. IR spectra showed no intense hydroxyl band between

3100 and cm 2 but showed strong methacrylate absorptions at 1640 and 1720 cm @ 2 PMR spectra consistent with the proposed structure:

7909196-3

<img file="SE445113B_D0038.tif" />

1,3-bis (4-methacryloxy butyl) tetramethyl disiloxane.

<td>Proton</td><td>ppm</td><td>Integrated top surface</td><td>multiplicity</td>

<td>hrs¹</td><td>7, O₅</td><td> 1</td><td>singlet</td>

<td>hrs²</td><td>⁶'⁵O</td><td> 1</td><td>singlet</td>

<td>hrs³</td><td> 3,0₀</td><td> 3</td><td>singlet</td>

<td>hrs⁴</td><td> 5,1₅</td><td> 2</td><td>triplet</td>

<td>hrs⁵</td><td> 2,7</td><td> 4</td><td>multiplet</td>

<td>hrs⁶</td><td> 1,6₅</td><td> 2</td><td>triplet</td>

<td>hrs⁷</td><td>in,²₀</td><td> 6</td><td>singlet</td>

The elemental analysis gave 13.6% Si (calculated 13.5%), 58.1% C (calculated 57.9%) and 9.4% (calculated 9.2%). The product was a clear, colorless, fragrant liquid. EXAMPLE II

96.9 gl, 1,3,3-tetramethyl-1,3-disila-2-oxacyclohexane from Silar Labs, Alplaus Road, Scotia, New York 12302, and 3.1 g of 1,3-bis (4) (methacryloxybutyl) tetramethyldisiloxane prepared in Example I was charged into a 200 ml round bottomed polymerization flask. 1.3 ml of Aldrich Chemical Co trifluoromethanesulfonic acid was added to the polymerization flask and the flask was sealed with a stopper. An increase in the viscosity of the piston contents and the development of heat was noted 2-3 minutes after the addition of the acid to the piston. The piston contents were stirred by means of a shaker overnight. Then the polymerization was stopped by adding 10 g of Na₂CO₃. For the viscous product

7909196-3 was added hexane and the solution was filtered to remove the carbonate. The hexane solution of the product is then washed 3 times with water and dried over MgSO₄. The hexane was removed from the product at reduced pressure. The viscosity of the product, measured with Gardner viscosity tubes, was 9.0 p. The number average and weight average molecular weight, as measured by gel permeation chromatography, were 12,300 and 31,700, respectively. The structure of the clear, colorless product was that of the following formula

<img file="SE445113B_D0039.tif" />

EXAMPLE III

Films of the viscous liquid prepared in Example II were cast between glass sheets using 1 wt.% Diethoxyacetophenone as a curing agent. The films were cured by irradiating the assembled cells in ultraviolet light for 2 hours. Colorless, optically clear, odorless, elastic and strong films were obtained. The cured polymer is represented by the three-dimensional network polymer shown below. The following physical properties were measured on an Instron Tester ASTM D 1708, no conditioning, using standard dog bone samples cut from 0.2 mm thick films. The speed was 0.64 cm / min.

In terms of module, it would be very advantageous if the module was below 300 to obtain a soft contact lens. Therefore, it is generally the case that the lower the module, the softer the contact lens.

In the case of elongation, it is generally preferred that the elongation is as high as possible.

In the case of oxygen transport, it is desirable that this ratio be maximized. This ratio should be greater than the ratio of oxygen required by the human cornea.

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Tensile strength

Tensile modulus

Elongation g / mm² g / mm²

118 %

<img file="SE445113B_D0040.tif" />

The oxygen transport ratio was determined by the following technique. Two chambers were filled with water at 32 ° C and these chambers communicated with each other through a common passage over which the material to be tested was placed. Nitrogen-gummed water was pumped into both chambers until the oxygen concentration was very low (md, 4 ppm). Thereafter, aerated water (oxygen concentration 8 8 ppm) was introduced into the lower chamber. An upper electrode sensitive to oxygen concentration had been placed in the upper chamber 35. This measured the apparent oxygen transport rate from the lower chamber through the material spm to be tested to the oxygen-emptied upper chamber.

790^196-3

The apparent oxygen transport rate for a membrane of 0.1 mm thickness seam prepared in Example II was

1.9 x 10 “οπΛ (O ^ J / s.cm ^ atm.

EXAMPLE IV ·

- The viscous 'liquid product prepared in Example · ΙΓ was mixed' with 1% by weight diethoxyacetophenone. and a suitable centrifugal molding contact lens shape was set. The mixture was centrifugal cast under suitable polymerization conditions as taught in U.S. Patent No. 3,408,429. The lens was optically clear, elastic and strong. EXAMPLE V

The viscous liquid product prepared in Example II was mixed with 30% by weight t-butyl styrene and 0.5% by weight di (sec-butyl) peroxide dicarbonate. Copolymer15 · films of this mixture were cast between glass sheets. The films were cured by heating the assembled cells for 0.5 h at 40 ° C and then 0.5 h at 60 ° C and then 0.25 h at 80 ° C. The glass panels are separated. The films were then kept at 80 ° C for 0.25 hour. The copolymer films were clear, colorless, odorless and extremely tough. 7909196-3