WO2011137457A1

WO2011137457A1 - Conducting polymer nanostructured composites and preparation methods thereof

Info

Publication number: WO2011137457A1
Application number: PCT/US2011/034857
Authority: WO
Inventors: Christina Baker
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-04-30
Filing date: 2011-05-02
Publication date: 2011-11-03
Anticipated expiration: 2012-10-30

Abstract

In one embodiment, a solvent exchange method for the preparation of a dispersion of a conducting material in a desired solvent is provided comprising, providing a first dispersion of the conductive material in a first solvent, wherein the conductive material has not been in a dry state prior to its dispersion in the first solvent, and providing a second dispersion of the conductive material in the desired solvent by exchanging the first solvent with the desired solvent while keeping the conducting material wet, wherein the conducting material is more efficiently dispersed in the desired solvent when compared with dispersing the conductive material in a dry state in the desired solvent.

Description

CONDUCTING POLYMER NANOSTRUCTURED COMPOSITES AND PREPARATION METHODS THEREOF

Priority claim

[0001] The present application claims priority to U.S. Provisional

Application 61 /330,31 1 , filed April 30, 201 0, which is incorporated herein by reference in its entirety.

Background

[0002] Inherently conducting polymers such as polyaniline have been polymerized for decades in forms that are difficult to process. The

conventional solution based polymerization methods result in micron-scale particulates of conducting polymers which are typically ground, dissolved in a strong organic solvent, and then filtered to remove undissolved particulates. This process is cumbersome, and limits the number of polymers which can be used for blends, because of the limited solvent range. Polyaniline is one of the most processable of the conducting polymers and even it has limited solubility in N-methyl pyrrolidinone, dimethylformamide and m-cresol. The poor solution processibility and strong inter-chain affinity results in difficulty when making polymeric blends. The polymer is either never fully solubilized, or has poor dispersibility in the polymer matrix. Conducting polymers are also not melt processable on their own. This has traditionally limited the range of commercial application for conducting polymers because most plastic consumer products are made by melt-processing.

[0003] Therefore, there is a need to provide a dispersion of inherently conducting polymers in a desired solvent without surfactants and/or fillers, and there is a need for conducting polymer composites having better solvent processibilities.

Summary

[0004] One aspect of the present disclosure relates to a solvent exchange method for the preparation of a dispersion of a conducting material in a solvent or a solvent mixture without the addition or use of surfactants and/or fillers and the solvent or solvent mixture does not disperse the dry conducting material without surfactants and/or fillers, or the solvent or solvent mixture disperses the conducting material more efficiently using this solvent exchange method than without using the solvent exchange method.

[0005] Another aspect of the present disclosure relates to a conducting polymer composite comprising a first material and a second material different from the first material, the first material comprises at least a first conducting material selected from the group consisting of conducting monomers, conducting oligomers, conducting polymers, and blends thereof; the first material and the second material are blended covalently and/or non- covalently; and the composite has an enhanced processability compared to the first material or the conducting polymer or oligomer.

[0006] Another aspect of the present disclosure relates to a method of preparing the conducting polymer composite.

Brief Description of the Drawings

[0007] Figure 1 : Conducting polymer composite formed by blending polystyrene and polyaniline nanofiber. [0008] Figure 2: Conducting polymer composite formed by blending polymethylmethacrylate (PMMA) and polyaniline nanofiber.

[0009] Figure 3: Conducting polymer composite formed by blending

Nylon 6,6 and polyaniline nanofiber shows the nylon threads as they were wound around a glass rod following polymerization.

[0010] Figure 4: Preparation scheme of conducting polymer composite formed by blending polyamide and polyaniline nanofiber covalently using polyaniline (A), diamine terminated polyaniline (B), or a derivative of either A or B (C), for partial substitution of some of the diamine in the synthesis of a polyamide.

Detailed Description

[0011] I) Solvent exchange methods

[0012] One aspect of the present disclosure relates to a solvent exchange method for preparing a dispersion of a conducting material in a solvent or a solvent mixture without the use of surfactants and/or fillers, where the solvent or solvent mixture generally does not disperse a dry conducting material without the use of surfactants and/or fillers. In another embodiment, the solvent or solvent mixture provides for dispersing the conducting material more efficiently using this solvent exchange method. As used herein the phrase more efficient dispersions means providing a more uniform dispersion (by, for example, having less agglomerate or small particulates in the dispersion), or providing substantially the same dispersion but in a shorter time period or under more mild conditions (e.g., lower temperature, without sonication methods) when compared to dispersing the same conducting material in the same solvent, solvent mixture or the second material without using the solvent exchange method. In both embodiments the conducting material is dispersed while wet, such that the conducting material is never allowed to dry until dispersion is complete. This is particularly useful where the conducting material is formed or produced in a solvent system.

[0013] The dispersion facilitates making conducting polymer composites formed by blending the conducting material and other materials through covalent and/or non-covalent interaction, and coating formulations (mixtures of inherently conducting polymers (ICPs) with other polymers or additives for robust coatings). The dispersions allow a desired mixture of the conducting material into a matrix polymer. If the ICP is well dispersed (i.e., doesn't form bundles or aggregates when mixed with another polymer), then it requires less material to achieve a desired level of conductivity and/or reach the percolation threshold of conductivity in the solid form of the composite.

[0014] Thus, when a dispersion is dried for use as a coating or as a solid polymer and the conductivity is reached through a percolating network of conductive material, less ICP incorporation is needed to reach conductivity. This can drastically reduce the cost of the conductive polymer composite.

[0015] According to one embodiment, a dispersion of a material in a desired solvent is prepared by a solvent exchange method comprising:

providing a first dispersion of the material in a first solvent where the first solvent is not the desired final solvent; and

providing a second dispersion of the material in a second solvent, where the second solvent is the desired final solvent, by exchanging the solvent of the first dispersion with the second solvent while keeping the material wet. [0016] As used herein, "material" can be conductive materials (e.g. conducting monomers, conducting oligomers, conducting polymers, and blends thereof) and non-conductive materials (e.g. non-conducting

monomers, non-conducting oligomers, non-conducting polymers and blends thereof) and blends thereof.

[0017] As used herein, "blend" means a mixture formed or to form a mixture of two materials through covalent interactions and/or non-covalent interactions.

[0018] As used herein, "dispersion" means a liquid-solid system, e.g., suspension, solution and swelled mixture; "disperse" means suspend, dissolve or swell a solid into a liquid to form dispersion. And, as set forth above, some methods disclosed herein will provide a more efficient dispersion when compared to prior art methods without the need for surfactants and/or fillers.

[0019] As used herein, a solvent can be a solvent, a mixture of more than one solvent, or a solution (e.g. aqueous solution).

[0020] Examples of conducting monomers include, without limitation, aniline, thiophene, pyrrole, and phenylene. Examples of conducting oligomer and conducting polymers include, without limitation, oligomers and polymers comprising the same or different conducting monomers, and derivatives thereof.

[0021] Derivatives of oligomers and polymers can be chemically modified derivatives and/or physically modified derivatives. Chemical modification may occur within the backbone, at an end of the backbone or on the sidechain of the oligomers and polymers. Physical modifications include, for example, doped polymers and oligomers, and nanostructured polymers and oligomers (e.g. nanofibers). Examples of physically and/or chemically modified derivatives of conducting oligomers and polymers include, without limitation, doped and undoped polyaniline, doped and undoped

polythiophene, doped and undoped polypyrrole, doped and undoped polyparaphenylene, doped and undoped oligoaniline, doped and undoped oligothiophene, doped and undoped oligopyrrole, doped and undoped oligoparaphenylene, doped and undoped polyaniline nanofibers, doped and undoped polythiophene nanofibers, doped and undoped polypyrrole nanofibers, doped and undoped polyparaphenylene nanofibers, alkyl functionalized derivatives thereof, sulfonate functionalized derivatives thereof, amine functionalized derivatives thereof, carbonyl functionalized derivatives thereof, hydroxyl functionalized derivatives thereof, carboxylic acid

functionalized derivatives thereof, and blends thereof.

[0022] Examples of non-conducting polymers include, without limitation, polyacrylamide, polyester, polyacrylate polymers, polyacrylate esters, polyacrylic acid, polyacrylonitrile, polyamic acids, polyaryl sulfonates, polybutadiene, polyamide, Nylon 6, Nylon 6,6, Nylon 6,8, polyphthalamide, aromatic polyamide, cellulose, cellulose triacetate, polyethylene oxide, polyisobutene, polyisoprene, polymethacrylate esters, polymethacrylic acids, polyphenylene sulfone, polypropylene oxide, polysiloxanes,

polymethylmethacrylate (PMMA), polystyrene, polyurethanes, polyvinyl acetates, polyvinyl alcohol (PVA), polystyrene sulfonic acid (PSSA), poly acrylic acid, polyvinyl butyryl, polyvinyl chloride, polyvinyl carbazole, polyvinylidine chloride, polyvinylidine fluoride, poly(N-vinyl pyrrolidone), polymers of substituted ethylene, derivatives thereof, and blends thereof.

[0023] Examples of the desired solvents include, without limitation, water, aqueous solutions, sulfuric acid, alcohols (e.g. ethanol, methanol, isopropanol), toluene, ketones (e.g. methyl ethyl ketone, acetone), halogenated solvents (e.g. chlorinated hydrocarbons such as carbon tetrachloride, chloroform; trichloroethanol, trifluoroacetic acid,

hexafluoroacetic acid), THF (tetrahydrofuran), DMF (dimethylformamide), DMSO (dimethyl sulfoxide), glycols, m-cresol, N-methyl-2-pyrrolidone (NMP), polar solvents, and combinations thereof.

[0024] In one embodiment, conductive materials that are dispersed in a solvent (e.g., water) or other reacting liquid can be dispersed in a solvent or other reacting liquid of choice if not substantially dried prior to further processing. Conventional methods such as rotary-evaporation (rotavap), using a fully dried filter cake, freeze drying, etc. cause too much particle aggregation and cannot fully disperse the material following complete drying. After the conducting polymers or oligomers are dispersed in the chosen solvent, they can be blended with another polymer that is dispersed in the same or a miscible solvent. In certain embodiments, the original solvent is fully removed to provide a stable dispersion for the formation of the conducting polymer nanostructures in the new dispersion. In certain embodiments, solvent exchange of a dispersion of is accomplished by filtration, centrifugation or dialysis based solvent exchange methods.

[0025] For a dispersion of a material in a first solvent, a filtration based solvent exchange method comprises filtering the dispersion to form a cake and then dispersing the cake into a desired solvent. The cake should be kept wet throughout the processing, and the cake is preferably not allowed to get to the point of cracking during filtration. In certain embodiments, the desired solvent is miscible with the first solvent. The low concentration of the first solvent allows a semi-stable dispersion. In certain embodiments, the method further comprises rinsing the filter cake with the desired solvent (at least once and preferably three times or more) prior to dispersing the filter cake into the desired solvent. The latter method is preferred when the desired solvent and the first solvent are not adequately miscible, when the first solvent is incompatible with the end application, or the dispersion in the desired solvent is not adequately stable.

[0026] For a dispersion of a material in a first solvent, a dialysis based solvent exchange method comprises adding the polymer dispersion to a dialysis bag with either end of the bag closed off; immersing the bag into a large (typically >10 times) volume of the desired solvent. In certain

embodiments, the mixture can be mixed, or left to sit unmixed for a period of time (e.g., 24 hours) until a sufficient amount of the first solvent is removed. At this point the solvent is poured off and more of the desired final solvent is added. This process can be repeated twice, thrice or more until a sufficient amount of the first solvent is removed.

[0027] For a dispersion of a material in a first solvent, a centrifugation based solvent exchange method comprises spinning the dispersion until a pellet is formed; decanting the supernatant; and adding the desired solvent. In certain embodiments, the spinning-decanting-adding process can be repeated twice, thrice or more until a satisfying amount of the first solvent is removed. This process results in dispersions with good stability, particularly when transferring conducting polymers/oligomers dispersed in water to other polar solvents such as alcohols (e.g., ethanol, methanol, isopropanol), and ketones (e.g. methyl ethyl ketone, acetone).

[0028] II) Conducting polymer composite

[0029] Another aspect of the present disclosure relates to a conducting polymer composite comprising a first material and a second material different from the first material. The first material comprises at least a first conducting material selected from the group consisting of conducting monomers, conducting oligomers, conducting polymers, and blends thereof. The second material comprises at least a first non-conducting material. The first material and the second material are blended together through covalent interactions and/or non-covalent interactions. The composite has an enhanced processability compared to the first material or the conducting polymer or oligomer. For example, the conducting polymer composite can be sufficiently dispersed in a solvent or a solvent mixture at a higher level of dispersion (e.g., a more efficient dispersion) than would otherwise be possible without using the disclosed methods and that cannot now be achieved without the use of surfactants and/or fillers.

[0030] The first material and the second material are independently selected from the group consisting of conducting materials, non-conducting materials and any blends thereof.

[0031] The mass ratio of the first material and the second material can be from about 5:1 to about 1 :500, from about 1 :1 to about 1 :50, from about 1 :1 to about 1 :1 0, from about 1 :1 to about 1 :5, from about 1 :2 to about 1 :1 00, from about 1 :2 to about 1 :50, from about 1 :2 to about 1 :10, and from about 1 :2 to about 1 :5.

[0032] The mass ratio of the first conducting material and the first non-conducting material can be from about 5:1 to about 1 :500, from about 1 :1 to about 1 :50, from about 1 :1 to about 1 :1 0, from about 1 :1 to about 1 :5, from about 1 :2 to about 1 :1 00, from about 1 :2 to about 1 :50, from about 1 :2 to about 1 :1 0, and from about 1 :2 to about 1 :5.

[0033] i) Covalent blending

[0034] In one embodiment, a conducting polymer composite is formed by blending a first material and a second material through covalent interaction. The first material or a part thereof may be incorporated into the backbones and/or the side chains of the second material, or a part thereof. In certain embodiments, non-covalent interactions may also exist during the formation of the covalently-blended conducting polymer composite.

[0035] Examples of the first conducting material include, without limitation, doped and undoped polyaniline, doped and undoped

polythiophene, doped and undoped polypyrrole, doped and undoped polyparaphenylene, doped and undoped oligoaniline, doped and undoped oligothiophene, doped and undoped oligopyrrole, doped and undoped oligoparaphenylene, doped and undoped polyaniline nanofibers, doped and undoped polythiophene nanofibers, doped and undoped polypyrrole nanofibers, doped and undoped polyparaphenylene nanofibers, alkyl functionalized derivatives thereof, sulfonate functionalized derivatives thereof, amine functionalized derivatives thereof, hydroxyl functionalized derivatives thereof, carbonyl functionalized derivatives thereof, carboxylic acid functionalized derivatives thereof, and blends thereof. The oligomers' degrees of polymerizations are 4 or larger.

[0036] The second material comprises monomers, and/or oligomers and/or polymers having functional groups that can form covalent bond with the first material, e.g. carbonyl groups, amine groups, alcohol groups, and carboxylic acid groups. Examples of the first non-conducting material of the second material include, without limitation, polyamide, aromatic polyamides, Nylon 6,6, Nylon 6,8, Nylon 6, polymers comprising polyamide monomers (e.g. caprolactam, hexamethylene diamine, adipic acid, terephthalic acid, and other polyamide monomers), paraphenylenediamine, polyphthalamide, polyurethane, polyester, monomers thereof, and blends thereof.

[0037] In certain embodiments, a functional group of the first material may be protected to avoid formation of undesired covalent bonds among the first material and/or between the first material and the second material. For example, an amine group of polyaniline may be protected via conventional organic chemistry.

[0038] In another embodiment, a conducting polymer composite comprising a first material and a second material is prepared by a method comprising:

1 ) dispersing the first material in a first desired solvent to provide a first pre-polymer dispersion;

2) dispersing the second material in a second desired solvent to provide a second pre-polymer dispersion; and 3) covalently blending the first pre-polymer dispersion and the second pre-polymer dispersion at a condition sufficient to form the conducting polymer composite.

[0039] In another embodiment, a conducting polymer nanostructured composite comprising a first material and a second material is prepared by a method comprising:

1 ) providing a pre-polymer mixture comprising the first material and the second material;

2) dispersing the pre-polymer mixture in a first desired solvent to provide a pre-polymer dispersion; and

3) covalently blending the first material and the second material in the pre-polymer dispersion at a condition sufficient to form the conducting polymer composite.

[0040] In another embodiment, a conducting polymer nanostructured composite comprising a first material and a second material is prepared by a method comprising:

2) dispersing the second material in the first pre-polymer dispersion to provide a second pre-polymer dispersion; and

3) covalently blending the first material and the second material in the second pre-polymer dispersion at a condition sufficient to form the conducting polymer composite. [0041] In another embodiment, a conducting polymer nanostructured composite comprising a first material and a second material is prepared by a method comprising:

1 ) dispersing the second material in a first desired solvent to provide a first pre-polymer dispersion;

2) dispersing the first material in the first pre-polymer dispersion to provide a second pre-polymer dispersion; and

3) covalently blending the first material and the second material in the second pre-polymer dispersion at a condition sufficient to form the conducting polymer composite.

[0042] In another embodiment, a pre-polymer dispersion comprising the first material and the second material in a first desired solvent may be further converted to a dispersion in a second desired solvent before covalently blending the first material and the second material at a condition sufficient to form the conducting polymer composite.

[0043] A desired solvent (e.g. the first desired solvent and the second desired solvent) can be the same as or compatible/miscible to a solvent that is suitable to the condition sufficient to form the conducting polymer composite. Examples of the desired solvents include, without limitation, water, aqueous solutions, sulfuric acid, alcohols (e.g. ethanol, methanol, isopropanol), toluene, ketones (e.g. methyl ethyl ketone, acetone), halogenated solvents (e.g. chlorinated hydrocarbons such as carbon tetrachloride, chloroform;

trichloroethanol; trifluoroacetic acid, hexafluoroacetic acid (HFIP)),

tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), glycols, m-cresol, N-methyl-2-pyrrolidone (NMP), polar solvents, and a combination thereof. The first desired solvent and the second desired solvent can be the same or different.

[0044] In certain embodiments, if the first desired solvent does not disperse, dissolve, or swell the first and/or the second material sufficiently after the material is dried, then the first pre-polymer dispersion can be prepared from a first dispersion comprising the first material and a first solvent according to the solvent exchange method described supra. In one embodiment, the first solvent can be a solvent that disperse, dissolve and/or swell the first and/or the second material sufficiently, e.g. without limitation, alcohols (including ethanol, methanol or isopropanol), DMSO, HFIP, m-cresol, NMP, acetone or a combination thereof. In another embodiment, the first solvent may be another solvent that does not disperse, dissolve and/or swell the first material sufficiently after the material is in a dry state. The first dispersion may be prepared by changing the solvent of a dispersion comprising the first material more than once using the solvent exchange method described supra. In both embodiments, the first desired solvent and the first solvent can be miscible or non-miscible.

[0045] In certain embodiments, the conducting polymer composite is a polyamide conducting polymer composite. The first material comprises a first conducting material. The second material comprises a polyamide (e.g. Nylon 6,6, Nylon 6,8, Nylon 6, polyphthalamide, aromatic polyamide), oligoamide, monomer to form a polyamide (e.g. hexamethylene diaminem adipic acid, caprolactam, polyphthalamide, terephthalic acid,

paraphenylenediamine), or a combination thereof. [0046] In certain embodiments, the first material is combined with one of the monomers of polyamide in solution prior to polyamide formation (Figure 4, the first material is an inherently conducting polymer, conducting oligomer or conducting polymer nanofibers, e.g. polyaniline, polythiophene, polypyrrole, oligoaniline, oligothiophene, oligopyrrole, polyaniline nanofibers,

polythiophene nanofibers, and polypyrrole nanofibers). The formed polyamide is incorporated with the first material during polymerization.

[0047] Additionally the first material can be chemically modified with functional groups (e.g. alkyl, amine, alcohol, sulfonate, carbonyl or carboxylic acid groups) through the use of functionalized oligomer initiators or

functionalized monomers (Figure 4). Functional groups can be incorporated either through the use of a functionalized initiator or functionalized monomers used in conjunction with an initiator molecule to induce nanostructure formation.

[0048] Referring to Figure 4, a preparation scheme of conducting polymer composite formed by blending polyamide and polyaniline nanofiber covalently using polyaniline (A), diamine terminated polyaniline (B), or a derivative of either A or B (C), for partial substitution of some of the diamine in the synthesis of a polyamide is ahown.

[0049] In certain embodiments, the first material comprises a

conducting polymer or oligomer in a nanostructured form (e.g. nanofibers).

[0050] Polyaniline and other conducting polymers typically require much effort to disperse them in solvents other than the limited solvents used to fully dissolve the polymers. For polyaniline, the typical solvents include N- methyl pyrrolidinone, m-cresol, DMF and a few others. These solvents fully dissolve the polymer and the polymer is often needed at higher percentage rates to achieve the percolation threshold to achieve conductivity in a blend. Utilizing the nanofibullar forms of polyaniline or other conducting polymers allows dispersion in a broad range of solvents, and incorporation at low loading levels to achieve conductivity.

[0051] An alternative method involves dispersion of a first material comprising polyaniline nanofibers into a solvent (e.g. water) with a second material comprising one (or more) of the monomers used to synthesize a matrix or structural polymer (e.g. polyamides). In one embodiment, a polyamide is synthesized using an interfacial polymerization with a diol in the acid phase and a diamine in an organic phase. Polyaniline can be

incorporated with additional amine groups by using p-phenylene diamine or other amine functionalized aniline or aniline oligomers. The polyaniline with additional amine groups will be taken up in place of the polyamide's diamine monomer for covalent incorporation of the polyaniline nanofibers into the polyamide during formation.

[0052] In one embodiment, a conducting polymer composite comprising Nylon 6,6 and polyaniline nanofiber has been synthesized, with polyaniline incorporated while drawing the nylon. This combination can result in covalent and non-covalent incorporation of the polyaniline into the polyamide matrix. The conducting polymer composite is prepared by mixing polyaniline nanofiber dispersions. [0053] ii) non-covalent blending

[0054] In certain embodiments, a conducting polymer composite is prepared by blending a first material and a second material through non- covalent interactions.

[0055] In certain embodiments, a conducting polymer composite comprising a first material and a second material is prepared by a method comprising:

1 ) mixing the first material and the second material to form a first mixture; and

2) dispersing the first mixture in a first desired solvent.

[0056] In certain embodiments, a conducting polymer composite comprising a first material and a second material is prepared by a method comprising:

2) dispersing the second material in a second desired solvent to provide a second pre-polymer dispersion; and

3) mixing the first pre-polymer dispersion and the second pre-polymer dispersion.

[0057] In certain embodiments, a conducting polymer composite comprising a first material and a second material is prepared by a method comprising:

1 ) dispersing the first material in a first desired solvent to provide a first pre-polymer dispersion; and

2) dispersing the second material in the first pre-polymer dispersion. [0058] In certain embodiments, a conducting polymer composite comprising a first material and a second material is prepared by a method comprising:

1 ) dispersing the second material in a first desired solvent to provide a first pre-polymer dispersion; and

2) dispersing the first material in the first pre-polymer dispersion.

[0059] In certain embodiment, the preparation of a conducting polymer composite further comprises a high energy mixing (e.g. sonication) to facilitate blending of the first and the second material.

[0060] In certain embodiments, if the first desired solvent cannot disperse, dissolve or swell the first and/or second material sufficiently, then the first pre-dispersion can be prepared from a first dispersion comprising the first material and a first solvent according to the solvent exchange method below. In one embodiment, the first solvent can disperse, dissolve and/or swell the first material sufficiently, e.g. without limitation, alcohols (e.g.

ethanol, methanol and isopropanol), DMSO, HFIP, m-cresol, NMP, acetone or mixture thereof. In another embodiment, the first solvent may be another solvent that does not disperse, dissolve and/or swell the first material sufficiently after the material is in a dry state. The first dispersion may be prepared by changing a solvent of a dispersion comprising the first material more than once using the solvent exchange method described supra. In both embodiments, the first and/or second desired solvent and the first solvent can be miscible or non-miscible.

[0061] In certain embodiments, the first material and the second material can disperse in the same or miscible solvents such as water, aqueous solutions, sulfuric acid, alcohols (e.g. ethanol, methanol,

isopropanol), toluene, ketones (e.g. methyl ethyl ketone, acetone), chlorinated solvents (e.g. chlorinated hydrocarbons such as carbon tetrachloride, chloroform; trichloroethanol; trifluoroacetic acid, hexafluoroacetic acid), THF, DMF, DMSO, glycols, m-cresol, NMP, polar solvents, and a combination thereof.

[0062] For example, aqueous dispersions can be used to form blends of conducting polymer (e.g. polyaniline) with PVA, PSSA, poly acrylic acid and other water soluble polymers.

[0063] These water soluble polymers may be useful additives for improved coatings, dispersion stability, end-product stability, shelf-life or matrix compatibility as necessary.

[0064] In another embodiment, the first material is polyaniline nanofibers, the second material comprises a polyamide (e.g. Nylon 6, Nylon 6,6, Nylon 6,8, polyphthalamide, aromatic polyamide), and the first desired solvent is sulfuric acid.

[0065] In another embodiment, the first material is polyaniline nanofiber, and the second material is PMMA and/or polystyrene, the first desired solvent is acetone. The conducting polymer composite is prepared using doped or undoped polyaniline nanofibers, or derivatives of polyaniline nanofibers.

[0066] In certain embodiments, the first material comprises a conducting polymer, and the second material comprises a filler polymer, examples include, without limitation, polyacrylamide, polyester, polyacrylate polymers, polyacrylate esters, polyacrylic acid, polyacrylonitrile, polyamic acids, polyaryl sulfonates, polybutadiene, polyamide, Nylon 6, Nylon 6,6, Nylon 6,8, polyphthalamide, aromatic polyamide, cellulose, cellulose tracetate, polyethylene oxide, polyisobutene, polyisoprene, polymethacrylate esters, polymethacrylic acids, polyphenylene sulfone, polypropylene oxide, polysiloxanes, PMMA, polystyrene, polyurethanes, polyvinyl acetates, PVA, PSSA, poly acrylic acid, polyvinyl butyryl, polyvinyl chloride, polyvinyl carbazole, polyvinylidine chloride, polyvinylidine fluoride, poly(N-vinyl pyrrolidone), polymers of substituted ethylene, derivatives thereof, and blends thereof. The filler polymer is dispersed in a second desired solvent, and is blended with the conducting polymer dispersed in a first desired solvent. The first desired solvent can be the same solvent as the second desired solvent, a miscible solvent(s) of the second desired solvent, a combination of miscible solvents of the second desired solvent, or a combination thereof. Examples of the miscible solvent include, without limitation, water, aqueous solutions, sulfuric acid, alcohols (e.g. ethanol, methanol, isopropanol), toluene, ketones (e.g. methyl ethyl ketone, acetone), chlorinated solvents (e.g. chlorinated hydrocarbons such as carbon tetrachloride, chloroform; trichloroethanol; trifluoroacetic acid, hexafluoroacetic acid), THF, DMF, DMSO, glycols, tricresol, NMP, polar solvents, and a combination thereof.

[0067] Once a conducting polymer composite is dispersed in a desired solvent, the dispersion can be used for further processed such as for coating and/or blends with other polymers. These methods are used to blend or coat conducting polymers with or onto other polymers, nanoparticles and substrates through the use of an appropriate solvent system. A dispersion of a conducting polymer composite in one solvent can be converted to a dispersion in another solvent using the solvent exchange method as described supra.

[0068] Low polarity polymers/oligomers may be more difficult to blend with conducting polymers/oligomers as the low polarity polymers/oligomers tend to be soluble in non-polar solvents, which do not typically disperse conducting polymers/oligomers (e.g. polyaniline nanofibers and conducting polymer nanofibers).

Examples

[0069] The following examples are provided to better illustrate the claimed invention and are not to be interpreted as limiting the scope of the invention. All specific compositions, materials, and methods described below, in whole or in part, fall within the scope of the present invention. These specific compositions, materials, and methods are not intended to limit the invention, but merely to illustrate specific embodiments falling within the scope of the invention. One skilled in the art may develop equivalent compositions, materials, and methods without the exercise of inventive capacity and without departing from the scope of the invention. It will be understood that many variations can be made in the procedures herein described while still remaining within the bounds of the present invention. It is the intention of the inventors that such variations are included within the scope of the invention. Example 1

[0070] Ten drops of 20% (w/w) aqueous NaOH solution was added to

10 mL of 5% (w/w) (aqueous) 1 ,6 hexyldiamine and stirred for 5 minutes.

Then, 300 mg of purified undoped polyaniline nanofiber dispersion at 2.5%

(w/w) was added and stirred for another 5 minutes. Stirring was stopped while 1 0 ml_ of 5% w/w of sebacoyl chloride in cyclohexanone was added to the aqueous solution. The conducting polymer composite was drawn from the interface using a hook and wound on a rod yielding a blue polymer strand. The composite was then washed by soaking in water and changing the water at least twice per day for at least one day. The polyaniline nanofibers of the composite were doped by soaking the composite in 1 M HCI until the composite is green (after approximately one hour) (Figure 1 ).

Example 2

[0071] A 10% w/w solution of Nylon 6,6 was made by dissolving the nylon in 50% concentrated sulfuric acid and 50% deionized water, and mixing for 12 hours. Polyaniline nanofiber dispersion (1 g, at a concentration of >20% w/w in water) was added to 10 g of the 10% w/w solution of nylon and mixed well. The mixture was cast to form a film and dried, or washed by centrifugation, dialysis or filtration prior to further use. Centrifugation was used to transfer the mixture to another solvent and/or remove excess acid. Removal of excess water under vacuum and/or elevated temperatures was used to increase the polymer chain length and strength of the nylon.

Example 3

[0072] A polymethylmethacrylate and polyaniline nanofiber blend was prepared by dissolving 20 g PMMA and 1 g of a polyaniline nanofiber filter cake (> 5% w/w) into 50 ml_ acetone and 2.5 ml_ 1 M HCI. The polyaniline blended into the polymer well and was allowed to dry in a 20 ml_ vial (Figure 2).

Example 4 [0073] A polystyrene and polyaniline nanofiber blend was made by adding 20 g polystyrene and 1 g polyaniline nanofiber filter cake (> 5% w/w) into 50 ml_ acetone and 2.5 ml_ 1 M HCI. The swollen polyaniline and polystyrene blend was separated from acetone, dried partially as a film and then transferred to a 20 ml_ vial to fully dry (Figure 3).

Example 5

[0074] Nylon 6,6 was dissolved in sulfuric acid and combined with polyaniline nanofibers with high energy mixing (e.g. sonication) at a 10:1 mass ratio.

Example 6

[0075] Nylon 6 was dissolved in sulfuric acid and combined with polyaniline nanofibers with high energy mixing (e.g. sonication) at a 10:1 mass ratio.

Example 7

[0076] PVA was blended with polyaniline nanofibers in water to provide a dispersion of polyaniline nanofibers and polyvinyl alcohol.

Claims

1 . A solvent exchange method for the preparation of a dispersion of a conducting material in a desired solvent comprising: providing a first dispersion of the conductive material in a first solvent, wherein the conductive material has not been in a dry state prior to its dispersion in the first solvent; and providing a second dispersion of the conductive material in the desired solvent by exchanging the first solvent with the desired solvent while keeping the conducting material wet; wherein the conducting material is more efficiently dispersed in the desired solvent when compared with dispersing the conductive material in a dry state in the desired solvent.

2. The method according to claim 1 , wherein the conducting material comprises monomers selected from the group consisting of aniline, thiophene, pyrrole, phenylene, and derivatives thereof.

3. The method according to claim 1 , wherein the conducting material is nanostructured.

4. The method according to claim 1 , wherein the desired solvent is selected from the group consisting of water, aqueous solutions, sulfuric acid, alcohols, ethanol, methanol, isopropanol, toluene, ketone, methyl ethyl ketone, acetone, halogenated solvents, chlorinated hydrocarbons, carbon tetrachloride, chloroform; trichloroethanol, trifluoroacetic acid, hexafluoroacetic acid (HFIP), tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), glycols, m-cresol, N-methyl-2-pyrrolidone (NMP), polar solvents, and combinations thereof.

5. The method according to claim 1 , wherein the first solvent is selected from the group consisting of DMSO, NMP, HFIP and m-cresol.

6. A conducting polymer composite prepared by a process comprising the steps of:

1 ) dispersing a first material in a first solvent to provide a first pre- polymer dispersion;

2) dispersing a second material in a second solvent to provide a second pre-polymer dispersion; and

3) blending the first pre-polymer dispersion and the second pre- polymer dispersion at a condition sufficient to form the conducting polymer composite; wherein:

the first material and the second material are different; the first material comprises at least a first conducting material selected from the group consisting of conducting monomers, conducting oligomers, conducting polymers, and blends thereof; the second material comprises a first non-conducting material, and the conducting polymer composite is substantially free of surfactants and fillers, and has a more efficient dispersion of the first conducting material compared with dispersing a dry first material.

7. The conducting polymer composite according to claim 6, wherein the first conducting material is selected from the group consisting of doped and undoped polyaniline, doped and undoped polythiophene, doped and undoped polypyrrole, doped and undoped polyaniline nanofibers, doped and undoped polythiophene nanofibers, doped and undoped polypyrrole nanofibers, alkyl functionalized derivatives thereof, sulfonate functionalized derivatives thereof, amine functionalized derivatives thereof, hydroxyl functionalized derivatives thereof, carboxylic acid functionalized derivatives thereof, carbonyl functionalized derivatives thereof, and blends thereof.

8. The conducting polymer composite according to claim 6, wherein the first non-conducting material selected from the group consisting of

polyacrylamide, polyester, polyacrylate polymers, polyacrylate esters, polyacrylic acid, polyacrylonitrile, polyamic acids, polyaryl sulfonates, polybutadiene, polyamide, Nylon 6, Nylon 6,6, Nylon 6,8, polyphthalamide, aromatic polyamide, cellulose, cellulose tracetate, polyethylene oxide, polyisobutene, polyisoprene, polymethacrylate esters, polymethacrylic acids, polyphenylene sulfone, polypropylene oxide, polysiloxanes, polystyrene, polymethylmethacrylate (PMMA), polyurethanes, polyvinyl acetates, polyvinyl alcohol (PVA), polystyrene sulfonic acid (PSSA), poly acrylic acid, polyvinyl butyryl, polyvinyl chloride, polyvinyl carbazole, polyvinylidine chloride, polyvinylidine fluoride, poly(N-vinyl pyrrolidone), polymers of substituted ethylene, derivatives thereof, and blends thereof.

9. The conducting polymer composite according to claim 6, wherein the first conducting material is incorporated in the backbone of the first nonconducting material.

10. The conducting polymer composite according to claim 9, wherein the first non-conducting material is selected from the group consisting of polyamide, aromatic polyamides, Nylon 6,6, Nylon 6,8, Nylon 6, polymers comprising polyamide monomers, polymers comprising caprolactam, polymers comprising hexamethylene diamine, polymers comprising adipic acid, polymers comprising terephthalic acid, paraphenylenediamine, polyphthalamide, polyurethane, polyester, monomers thereof, and blends thereof.

1 1 . The conducting polymer composite according to claim 6, wherein the first material and the second material are blended non-covalently.

12. The conducting polymer composite according to claim 1 1 , wherein the first material comprises polyaniline nanofiber, and the second material is selected from the group consisting of PVA, PSSA, PMMA, polystyrene, Nylon 6, Nylon 6,6, and blends thereof.

13. The conducting polymer composite according to claim 6, wherein the first solvent is the same as or miscible in the second solvent.

14. The conducting polymer composite according to claim 6, wherein the first solvent is the second pre-polymer dispersion.

15. The conducting polymer composite according to claim 6, wherein the second solvent is the first pre-polymer dispersion.

16. The conducting polymer composite according to claim 6, wherein the first solvent and the second solvent are the same, and the first material and the second material are mixed together before dispersing in the first solvent.

17. The conducting polymer composite according to claim 6, wherein the first solvent and the second solvent are independently selected from the group consisting of water, aqueous solutions, sulfuric acid, alcohols, ethanol, methanol, isopropanol, toluene, ketones, methyl ethyl ketone, acetone, halogenated solvents, chlorinated solvents, chlorinated hydrocarbons such as carbon tetrachloride, chloroform; trichloroethanol, trifluoroacetic acid, hexafluoroacetic acid, THF, DMF, DMSO, glycols, m-cresol, NMP, polar solvents, and combinations thereof.

18. The conducting polymer composite according to claim 6, wherein the first material more efficiently disperses in a third solvent than in the first solvent, the method further comprising: providing a third dispersion of the first material in the third solvent; and providing the first pre-polymer dispersion of the first material in the first solvent by exchanging the third solvent with the first solvent while keeping the first material wet.

19. The conducting polymer composite according to claim 18, wherein the first solvent is selected from the group consisting of DMSO, NMP, hexafluoroisopropanol and m-cresol.