Fabrication method of nanomaterials using block copolymer templates

Method for manufacturing nanomaterials using agglomerated copolymer template

The present invention relates to a method for manufacturing nanomaterials; in particular, it relates to a method for manufacturing nanocomposites and nanomaterials by using agglomerated copolymer template.

Because of the mutual influence of the immiscibility of the interlinked segments and the chemical bonding of the clustered copolymers, the temperature is below a certain temperature, which is called the order-disorder transition temperature (order-disorder transition temperature). Self-assembly forms microphase separation, self-assembly and self-ordering form an ordered microstructure with the lowest Gibbs free energy state in thermodynamics. After the microscopic phase separation, the domain-size is about tens of nanometers. Therefore, the cluster-linked copolymer will form a microstructure at a temperature lower than the order-disorder transition temperature, and the composition changes according to the volume fraction of the molecular cluster-linked segment, and there are spheres, hexagonal cylinders, laminates, and special The bicontinuous phase (bicontinuous or gyroid) or perforated layer (perforated layer) structure. From this, it can be seen that the biggest advantage of the two-cluster copolymer is that it has the characteristics of nanometer size, diversification, and periodic structure, and can form a wide range of arrays, which has high academic and application value.

Professor Wang Zhonglin of Georgia Institute of Technology published a series of synthesis and applications of inorganic nanowires and nanobelt, including the manufacture and property measurement of sensors or nano-generators. The attention of the world has attracted the investment and research boom of other related scholars. The popularity and importance of this field can be seen. Among them, inorganic spiral nanowires have attracted people's attention because of their special properties and applications in terms of mechanical strength and optical applications. There are many ways to prepare inorganic nanomaterials and their composites. They mainly include a vapor-liquid-solid growth process, or a template with nanopores, combined with chemical vapor deposition (chemical vapor deposition). ), electrochemical deposition (electrodeposition), sol-gel process (sol-gel process) and other methods. In addition, the self-assembly of surfactants and inorganic precursors can also be used to synthesize inorganic nanowires and their composites with different structures; however, how to prepare inorganic nanomaterials with ordered arrangements and different structures? It is still a very challenging research at this stage.

There are currently two main methods of filling other different materials with porous templates to prepare nano-inorganic materials with different structures: anodic aluminum oxide (AAO) template and cluster copolymer system. However, most of the holes in the AAO template have a cylinder structure, and they are hard materials, which will be inconvenient for subsequent processing. In addition, the size of the holes in the AAO template are mostly above the micron level. In addition, currently commonly used agglomerated copolymer systems can include polystyrene-polymethylmethacrylate (PS-PMMA) system and polystyrene-polyimine (PS-PI) system. The PS-PMMA system uses ultraviolet light (UV) to remove the PMMA end to obtain the PS porous template. However, because of the penetration of ultraviolet light, the thicker the thickness, the more difficult it is for ultraviolet light to penetrate and remove PMMA. Therefore, this system Most of them can only be made into thin films; in addition, the remaining small molecules after UV decomposition of PMMA must be carried out by solvents, which requires two steps, dry and wet. However, the PS-PI system uses ozone to remove the PI side, but the reason is the same as the above. The problem of gas permeability and the complicated steps of dry and wet, and PS-PI can only be used for film applications.

The purpose of the present invention is to provide a method for manufacturing nanomaterials by using agglomerated copolymer template, which can produce nanostructures with periodic and regular arrangements and made of ceramic/polymer, metal/polymer or polymer. / Composite materials composed of polymers, and organic/inorganic, inorganic/inorganic composite nanomaterials or inorganic nanomaterials with specific nanostructures.

According to another object of the present invention, a method for manufacturing nanomaterials using a co-polymer template is provided, which includes the following steps: First, a polymerized polymer of at least one decomposable monomer and at least one non-decomposable monomer is provided The group of linked copolymers. The agglomerated copolymer is used to prepare the agglomerated copolymer bulk, and the decomposable part of the agglomerated copolymer bulk is formed into a plurality of nanostructures arranged periodically. Then, by selectively hydrolyzing the agglomerated copolymer block material, the decomposable part of the chain segment is cleaved. After removing the decomposable part, an agglomerated copolymer template with multiple pores can be obtained. The pore diameter of these pores or the distance between the centers of two adjacent pores is 15-80 nanometers. Thereafter, a filling material is filled in the hole to obtain a composite material with the same structure as the agglomerated copolymer block material. Finally, ultraviolet light (UV), low-temperature calcination, organic solvents or supercritical fluids can be used to remove the agglomerated copolymer template of the composite material to obtain the same reverse phase as the above-mentioned plural nanostructures. A plurality of nanomaterials. Among them, the nano-microstructure system can include sphere, cylinder, lamella, special bicontinuous or gyroid, perforated layer or helix. And other structures.

Based on the above, the method of manufacturing nanomaterials by using agglomerated copolymer template according to the present invention can have the following advantages:

(1) The agglomerated copolymer template prepared by the present invention is composed of a polymer, which is a soft material, and has the advantages of simplicity and low cost in adding tools.

(2) The present invention can produce block-shaped or film-shaped agglomerated copolymers, which has a greater breadth in application.

(3) In the present invention, the decomposable part of the agglomerated copolymer block can be completely removed by a hydrolysis reaction, and a porous agglomerated copolymer template can be completed in one step.

(4) Taking advantage of the ability of polymer to be aligned, after removing the decomposable parts after alignment, a porous polymer template with a wide range of alignment, clear structure and good regularity can be obtained. Great application value.

(5) The present invention can not only produce nanomaterials with different nanostructures, but also the agglomerated copolymer block, agglomerated copolymer template and composite material obtained in the manufacturing process, and can also be applied to other materials based on its functionality. Component manufacturing or property measurement.

Please refer to Figure 1, which is a flow chart of the method for manufacturing nanomaterials using a cluster copolymer template of the present invention, which may include: step S11, providing a cluster copolymer, which may include at least one decomposability The monomer and at least one non-decomposable monomer are polymerized. In step S12, the agglomerated copolymer block is prepared by using the agglomerated copolymer, and its decomposable part is formed into a plurality of nanostructures arranged periodically. Then, step S13, selectively hydrolyzing the block of the agglomerated copolymer to cleavage the decomposable part of the chain, and after removing the decomposable part, a template of the agglomerated copolymer with a plurality of pores is obtained, the pore size of which is or The distance between the centers of two adjacent holes is 15-80 nanometers. Then, in step S14, a filling material is filled in these pores to obtain a composite material including a plurality of nanostructures as described above, and in step S15, ultraviolet light, low temperature sintering, organic solvent or supercritical fluid is used The agglomerated copolymer template of this composite material is removed to obtain a plurality of nanomaterials with a plurality of nanostructures. In addition, step S12 may further include dissolving the agglomerated copolymer in a solvent, and then volatilizing the solvent to produce the agglomerated copolymer block. The execution of step 14 is to fill the selected filling material into a plurality of holes by the solution-gel method, electrochemical synthesis method or chemical sedimentation method.

The plurality of monomers selected in this method can include palm-like molecules and non-palp-like molecules, and the palm-like molecules can be decomposable. Each nanostructure of the formed plural nanostructures can be a sphere, a cylinder, a laminate, a special dual continuous phase, a perforated laminate or a spiral structure, and the shape of the nanostructure can be a group The volume fraction of the copolymer block material is controlled. Among them, if each nanostructure is spherical, the entire nanostructure can be periodically arranged into a body cubic structure, and if it is a cylinder, the entire nanostructure can be periodically arranged. Arranged into a hexagonal most densely packed cylinder structure, which can also be called a hexagonal cylinder structure. In addition, the filling material can be ceramic material, polymer material, metal material or a combination thereof, so that the resulting composite material can be composed of ceramic/polymer, metal/polymer, or polymer/polymer. Nanomaterials can include organic/inorganic composite nanomaterials or inorganic nanomaterials.

Please refer to FIG. 2, which is a schematic flow diagram of a number of embodiments of the method for manufacturing nanomaterials using a cluster copolymer template according to the present invention. In the figure, Figures S21-A to S21-E are the use of biodegradable monomers poly-L-lactide (L-lactide, L-LA), poly-D-lactide (D-lactide, D-LA)) Or poly D, L-lactic acid (D, L-lactide) and the non-biodegradable monomer styrene (styrene) polymerized to form a co-polymer polystyrene-poly L-lactic acid (PS-PLLA), or poly Styrene-poly D-lactic acid (PS-PDLA) or polystyrene-poly D,L-lactic acid (PS-PLA), prepared PS-PLLA, PS-PDLA or PS-PLA agglomerated copolymer block material . Among them, the PLLA, PDLA, or PLA series that are compatible and biodegradable can form different nanostructures according to the different volume fractions of PLLA, PDLA, or PLA and styrene, as shown in the figure, which can include cylinders. Body (Figure S21-A), helix (Figure S21-B), gyroid (Figure S21-C), laminate (Figure S21-D), and perforated laminate (HPL) (Figure S21-E).

Figures S22-A to S22-E are respectively the use of alkaline solution to remove the PLLA, PDLA or PLA polymer components through hydrolysis, and the resulting agglomerated copolymer template with multiple pores, the shape of the pores is the same as the original PLLA, PDLA or PLA have the same shape, and the aperture or the distance between the centers of two adjacent holes is 15-80 nanometers. Figures S23-A to S23-E respectively show the concept of combining the nanoreactor, in which ceramics, metals or polymers are filled in by a solution-gel (sol-gel) process, electrochemical synthesis or chemical precipitation With different filling materials, composite materials with various compositions of ceramics/polymers, metals/polymers or polymers/polymers with various microstructures are prepared. And, Figures S24-A to S24-E respectively show that after removing the polymer template by ultraviolet light (UV), an amorphous nanomaterial can be obtained; it can also be removed by low-temperature sintering to remove the polymer agglomeration copolymerization. The material template is obtained, and a nanomaterial with a crystal phase (crystal) is obtained.

Among them, the preparation method of the above-mentioned agglomerated copolymer PS-PLLA can be as follows (the preparation method of the agglomerated copolymer PS-PDLA and PS-PLA is the same as the following principle): In order to achieve partial biodegradability The preparation of the group-linked copolymer can be based on its double headed initiator synthesis characteristics, and the various selectivity of its polymerizable monomers during the living polymerization reaction process. , Co-polymerizing biodegradable monomers (esters) and non-biodegradable monomers to provide a partially biodegradable cluster copolymer system. Therefore, firstly, the method of atom transfer radical polymerization was used to synthesize a series of polyester-based biodegradable double co-polymers. The method of synthesis was two-stage sequential living polymerization. First, living free radical polymerization was used ( Atom transfer radical polymerization is used to prepare styrene polymers with narrow molecular weight distribution; then, living ring opening polymerization is performed to achieve the purpose of copolymerization.

As shown in Figure 3, taking PS-PLLA as an example, the experimental flow diagram of the synthetic cluster-linked copolymer of the present invention is shown in DHI₄-Cl(HOCH₂CH(CH₃)₂CH₂OC(=O)CHCl(CH₃)) as the initiator to carry out the atom transfer radical polymerization reaction of styrene monomer, copper bromide (CuBr) is added as a catalyst in the reaction system, hexamethyltriethylenetetramine (HMTETA) or pentamethyl Pentamethyldiethylenetriamine (PMDETA) is used as a carrier (ligand). After adding styrene monomer, the polymer polymerization reaction is carried out at a temperature of 110°C. When the solution becomes a solid state and no longer flows, the reaction system is instantaneously cooled by an ice bath to terminate the reaction. Dissolve the polymer with toluene and pass through a silicon gel to remove excess copper ions. At this time, the solution turns from blue-green to colorless, clear and thick. Then add methanol to re-extract the PS polymer to remove excess monomers. After being with the carrier, the purification and extraction are completed, and the second-stage lactic acid monomer ring-opening polymerization reaction can be carried out after drying to remove the methanol. The second stage of living polymerization, mainly using the PS-OH synthesized in the first stage as the initiator, L-lactic acid (L-LA, a kind of ester) as the monomer, stannous octoate (Sn(Oct)₂) As a catalyst, in order to increase the uniformity of the reaction system, a small amount of toluene is added as a solvent. The reaction temperature is 110°C. The ring-opening polymerization reaction is completed in about 3-5 hours. The L-lactic acid monomer will be connected to the PS- After OH, a ring-opening polymerization reaction is carried out to form a PS-PLLA co-polymer. After the reaction is terminated by cooling in an ice bath, dichloromethane is added to dissolve PS-PLLA, and then purified and extracted with methanol, and PS-PLLA polymer powder can be obtained after drying.

Gel Permeation Chromatography (Gel Permission Chromatography, GPC) is used to carry out the molecular weight and molecular weight distribution of the synthesized PS. Because the molecular weight of polyesters measured by GPC is different from the actual molecular weight, it is The molecular weight of the polyester segment will be measured by means of Nuclear Magnetic Resonance (NMR), but the determination of the molecular weight distribution of copolymers still relies on the results measured by GPC.

In addition, the preparation method of the PS-PLLA duplex copolymer block described in Figure 2 and the identification of its nanostructure can be described as follows (Preparation of PS-PDLA and PS-PLA block copolymer The method and identification system are the same as the following principles): Dichloromethane (dichloromethane) is used as a solvent, and a 10% by weight solution of the agglomerated copolymer is prepared with dichloromethane as a solvent, and the solution is volatilized by the solvent at room temperature. The formation of microscopic phase-separated agglomerated copolymer block. As the agglomerated copolymer solution, the volatilization of the solvent will induce crystallization, resulting in a change in morphology. Therefore , it can be used with a micro-difference scanning thermal card (DSC) to coat the agglomerated copolymer block material made by solvent coating. , Heat to a constant temperature above the melting point for one minute, remove the thermal history of the test piece, and then rapidly drop to -50°C at a temperature drop rate of 150°C/min to prepare agglomerated copolymer block material with microscopic phase separation morphology. Then use a microtome to perform ultra-thin sectioning to make the sample with a thickness of tens of nanometers, and then use transmission electron microscopy (TEM) to observe the morphology of the nanostructure. Analysis and identification, and will be combined with a small angle X-ray scatterometer (small angle X-ray The structure diffraction results of scattering, SAXS) verify the results observed by the transmission electron microscope. The ordered microstructure of this agglomerated copolymer block can be identified by the relative position of the d-spacing measured by the small-angle X-ray scattering spectrum according to the diffraction Bragg's rule. If the ordered microstructure disappears, it will be diffracted. The map will show a disordered molten state map. The morphology observation of TEM is based on the mass-thickness contrast of dyeing. For example, as shown in Figure 4, the microscopic phase separation structure system of the bipolymer bulk material is subjected to ruthenium tetroxide (RuO₄) Dyeing TEM quality and thickness comparison images, you can find different microscopic phase separation structures. Figure 4A shows the helix microscopic phase separation structure, and Figure 4B shows the gyroid microscopic phase separation structure.

Next, the preparation method of the agglomerated copolymer template with only PS composition as described in Figure 2 can be described as follows: Use polyester-based biodegradable agglomerated copolymer system block material, because one group becomes biological The decomposable material is decomposed by the hydrolysis reaction of the ester group of the polyester polymer to decompose the decomposable area to produce a nano-sized agglomerated copolymer template. After high temperature denucleation PS-PLLA agglomerated copolymer bulk (bulk), put it into the lysis solution (Vol%, 0.5N sodium hydroxide: methanol=7:10), stir at 50°C for 7 days, and then wash Stir and immerse the liquid for 1 day (Vol%, methanol: water=1:1). After taking it out and drying it, it can be seen with naked eyes that the agglomerated copolymer block has changed from the initial transparent block to the white opaque block, which means PLLA Part of it has been lysed by the lye, and the rest is the agglomerated copolymer template composed of PS and porous. NMR measurement can be used to identify whether PLLA is completely lysed.

In addition, the composite materials with different compositions described in Figure 2 such as silicon dioxide (SiO₂)/PS, Titanium Dioxide (TiO₂)/PS or barium titanate (BaTiO₃The preparation of composite materials such as )/PS are as follows: (1) Put the PS co-polymer template into a solution of Tetraethyl orthosilicate (TEOS). After uniformly stirring, place it at room temperature and stir for 3 days, then put it in an oven containing saturated water vapor at 50°C, and let it stand for 5 days. When the solution forms a glassy substance, SiO can be obtained.₂/PS nanocomposites. (2) Similarly, put the PS cluster copolymer template into a solution of Titanium (IV) isopropoxide (TTIP). After uniformly stirring, place it at room temperature and stir for 3 days, then put it in an oven containing saturated water vapor at 50°C, and let it stand for 5 days until the solution forms a glassy substance, namely TiO₂/PS nanocomposites. (3) Similarly, the barium hydroxide (Ba(OH)₂) Is dissolved in acetic acid, and then mixed into the TTIP solution. After uniformly stirring, place it at room temperature and stir for 3 days, then put it in an oven containing saturated water vapor at 50°C and let it stand for 5 days. When the solution forms a glassy substance, BaTiO is obtained.₃/PS nanocomposites. A microtome is used to conduct ultra-thin sectioning to make the sample with a thickness of several tens of nanometers, and then use TEM to observe the morphology. For example, as shown in Figure 5, Figure 5A is a PS-PLLA section observed by TEM, with RuO₄The PS part is dyed, so the dark part is the main PS phase, and the white part is PLLA; and the 5B picture is the TEM observation of SiO₂/PS slice, without RuO₄Dyeing, so the main phase of PS is white area, SiO₂Because the electron cloud density is relatively high and the color is darker under TEM, the comparison between before and after filling the template shows that SiO₂Has been filled in the holes of the agglomerate copolymer template. In addition, Figures 6A and 6B respectively show the agglomerate copolymer template filled with TiO₂Later TEM section observation and X-ray energy spectrum dispersion analyzer (Energy Dispersive X-ray Spectrometer, EDS) elemental analysis chart, and the 7A and 7B pictures are the cluster copolymer template filled with BaTiO₃The following TEM section observation and EDS elemental analysis diagram show that TiO₂With BaTiO₃All are filled into the nano-holes.

Finally, the nanomaterials described in Figure 2 can be prepared by a solution-gel process. After removing the PS co-polymer template by ultraviolet light (UV), amorphous nanoinorganic materials can be obtained; The polymer template is removed by low-temperature sintering (550°C) to obtain a nano-inorganic material with a crystalline phase. Scanning electron microscopy (SEM) morphological observation is used to analyze and identify the microstructure. For example, as shown in Figure 8, it is a SiO prepared from a PS-PLLA cluster copolymer template with a gyroid nanostructure.₂/PS nanocomposite SEM image, among them, the figure 8A is the structure of the block copolymer, and the figure 8B is the double-polymer SiO₂/PS nanocomposite is cracked by UV, and the amorphous interpenetrating network structure is obtained, and the figure 8C is the double-polymer SiO₂The /PS nanocomposite is sintered and cracked at low temperature to obtain a crystalline network structure. In addition, for example, as shown in Figure 9, it is a SiO prepared from a PS-PDLA cluster copolymer template with a helix nanostructure.₂/PS nanocomposite SEM image, among them, the figure 9A is the structure of the block copolymer of the polymer, and the figure 9B is the structure of the double polymer of SiO₂/PS nanocomposite is cracked by UV, and the amorphous interpenetrating network structure is obtained, and the figure 9C is the two-polymer SiO₂The /PS nanocomposite is sintered and cracked at low temperature to obtain a crystalline network structure.

The present invention utilizes the bottom-up method described above to synthesize a clustered copolymer template with structural diversity, except that it can be filled with SiO₂, TiO₂BaTiO₃In addition, you can also fill in other different filler materials, such as polymer or metal with functional materials, so as to prepare a variety of functional nanocomposites. After removing the cluster copolymer template, you can also get Various types of nanomaterials in different shapes. Using such a technology platform, under the arrangement and combination of nano-microstructures and different filling materials, it is bound to be able to develop a series of diversified nano-materials, which is indeed a promising technology.

In addition, the present invention can not only prepare a block-shaped agglomerated copolymer block material from the agglomerated copolymer, but also a film-shaped agglomerated copolymer film, and then obtain a porous film-shaped agglomerated copolymer. template. Taking PS-PLLA as an example, its preparation method is as follows: 1wt% agglomerated copolymer PS-PLLA solution is spin-coated on the conductive substrate indium tin oxide (ITO), and With proper adjustment of the solvent and volatilization rate, it is possible to prepare an agglomerated copolymer film containing nano-columnar microstructures with a thickness of about 70 nm and a regular arrangement of vertical orientation. In order to increase the adsorption between the agglomerated copolymer film and the inorganic conductive substrate, to avoid the subsequent wet process of PLLA cracking, the agglomerated copolymer film will be desorbed, so organic molecules are used on the ITO base. Chemical modification on the surface of the material can effectively increase the adsorption capacity of organic and inorganic interfaces. Then, the prepared agglomerated copolymer film is immersed in a sodium hydroxide (NaOH)/methanol (methanol) aqueous solution to remove the PLLA segments, and a template of the agglomerated copolymer with a hole size of about 15-20 nm can be obtained. As shown in Figure 10, it is an image obtained by scanning probe microscopy (SPM) after the PLLA part of the agglomerated copolymer film is cleaved off.

Then, an electrochemical synthesis method can be used to fill the filler material into the holes of the above-mentioned agglomerated copolymer template to prepare a nanocomposite film. Its preparation method, taking the filler material of the conductive polymer aniline monomer as an example, can be described as follows: Dissolve the conductive polymer aniline monomer in a dilute sulfuric acid aqueous solution, and then use the three-pole method (work, contact, Reference electrode) method, using ITO coated with a hole template as the working electrode, platinum electrode as the contact electrode, and Ag/AgCl electrode as the reference electrode. A reaction potential is applied in the electrolytic cell to allow the polymer monomer to penetrate and diffuse, The way of electrochemical reaction is to conduct electropolymerization on the conductive substrate. In order to allow the electroplating solution to diffuse into the organic nanopores, a tertiary alcohol was added as a surfactant in the experimental process, and then through capillary force, the aniline electroplating solution can effectively diffuse into the pores for electropolymerization. From the experimental results, it is also found that if the electropolymerization reaction rate is too fast, it is more difficult to control the uniformity of the growth of aniline in different pores, which affects the final conductive polymer distribution, and through the pulse plating method and the combination of micro current Under the control of, the conductive polymer can be uniformly deposited in the organic nano-pores of the PS to prepare a conductive polymer/polymer nanocomposite film. For example, as shown in Fig. 11 and Fig. 12, the conductive polymer is filled in the holes of the agglomerated copolymer template, and the scanning probe microscope (scanning probe microscope) Images taken by microscopy, SPM) and SEM.

The above descriptions are merely illustrative and not restrictive. Any equivalent modifications or alterations that do not depart from the spirit and scope of the present invention should be included in the scope of the appended patent application.

<p>S11-S15. . . Step flow chart</p><p>as well as</p><p>S21-S24. . . Step flow chart</p>

Figure 1 is a flow chart of the method for manufacturing nanomaterials using agglomerated copolymer template according to the present invention;

Figure 2 is a schematic flow diagram of multiple embodiments of the method for manufacturing nanomaterials using agglomerated copolymer template according to the present invention;

Figure 3 is a schematic diagram of the experimental process of synthesizing a cluster-linked copolymer using PS-PLLA as an example of the present invention

Figure 4 is a comparison image of TEM mass thickness of the double-copolymer block of the present invention dyed with ruthenium tetroxide;

Fig. 5A is a TEM image of the PS-PLLA bipolymer block material of the present invention;

Figure 5B is the SiO of the present invention₂TEM image of /PS composite material;

Figure 6A is the TiO of the present invention₂TEM image of /PS composite material;

Figure 6B is the TiO of the present invention₂/PS composite material EDS element analysis diagram;

Figure 7A shows the BaTiO of the present invention₃TEM image of /PS composite material;

Figure 7B shows the BaTiO of the present invention₃/PS composite material EDS element analysis diagram;

Figure 8 is the SiO prepared by the PS-PLLA cluster copolymer template with double-helical nanostructures of the present invention₂/ SEM image of PS nanocomposite;

Figure 9 is the SiO prepared by the PS-PDLA cluster copolymer template with spiral nanostructure of the present invention₂/ SEM image of PS nanocomposite;

Figure 10 is the SPM diagram of the agglomerated copolymer template obtained by cleaving the PLLA part of the agglomerated copolymer film according to the present invention;

Figure 11 is the SPM diagram of the present invention after the conductive polymer is filled into the holes of the agglomerated copolymer template; and

Figure 12 is the SEM image of the present invention after the conductive polymer is filled in the holes of the agglomerated copolymer template.