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Publication numberUS20030155554 A1
Publication typeApplication
Application numberUS 09/208,528
Publication dateAug 21, 2003
Filing dateDec 9, 1998
Priority dateNov 29, 1995
Also published asUS5928566, US6616863
Publication number09208528, 208528, US 2003/0155554 A1, US 2003/155554 A1, US 20030155554 A1, US 20030155554A1, US 2003155554 A1, US 2003155554A1, US-A1-20030155554, US-A1-2003155554, US2003/0155554A1, US2003/155554A1, US20030155554 A1, US20030155554A1, US2003155554 A1, US2003155554A1
InventorsMarie Angelopoulos, Yun-Hsin Liao, Ravi F. Saraf
Original AssigneeMarie Angelopoulos, Yun-Hsin Liao, Ravi F. Saraf
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Isotropic, electroconductivity
US 20030155554 A1
Abstract
Materials containing precursors to electrically conductive polymers and electrically conductive polymers are described which have a high degree of crystallinity. The high degree of crystallinity is achieved by preparing the materials under conditions which provide a high degree of mobility to the polymer molecules permitting them to associate with one another to form a crystalline state. High levels of electrical conductivity are achieved in in the electrically conductive materials without stretch orienting the material. The enhanced electrical conductivity is isotropic as compared to a stretch oriented film which has isotropic electrical conductivity.
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Claims(26)
What is claimed is:
1. A structure comprising:
additive and a polymer selected from the group consisting of a precursor to an electrically conductive polymer and an electrically conductive polymer;
said additive provides mobility to said polymer to allow said polymer to associate with one another to achieve at least one crystalline region.
2. A structure according to claim 1, wherein said admixture is electrically conductive and has an isotropic electrical conductivity.
3. A structure according to claim 1, wherein said additive is selected from the group consisting of plasticizers and diluents.
4. A structure according to claim 1, wherein said additive is a plasticizer selected from the group consisting of:
Adipic acid derivatives Sebacic acid derivatives Azelaic acid derivatives Stearic acid derivatives Benzoic acid derivatives Succinic acid derivatives Citric acid derivatives Sulfonic acid derivative Dimer acid derivatives Terpentines Epoxy derivatives Terpentine derivatives Fumaric acid derivatives Siloxanes Glycerol derivatives Polysiloxanes Isobutyrate derivatives Ethylene glycols Isophthalic acid derivatives Polyethylene glycols Lauric acid derivatives Polyesters Linoleic acid derivative Sucrose derivatives Maleic acid derivative Tartaric acid derivative Mellitates Terephthalic acid derivative Myristic acid derivatives Trimellitic acid derivatives Oleic acid derivatives Glycol derivatives Palmitic acid derivatives Glycolates Paraffin derivatives Hydrocarbons Phosphoric acid derivatives Phosphonic acid derivatives Phthalic acid derivatives Polysilanes Ricinoleic acid derivatives
5. A structure according to claim 1, wherein said polymer is selected from the group consisting of substituted and unsubstituted polyparaphenylene vinylenes, polyparaphenylenes, polyanilines, polythiophenes, polyazines, polyfuranes, polypyrroles, polyselenophenes, polythianaphthenes, poly-p-phenylene sulfides, polyacetylenes formed from soluble precursors, combinations thereof and blends thereof with other polymers and copolymers of the monomers thereof.
6. A structure according to claim 1, wherein said structure is stretch oriented.
7. A structure comprising:
a plasticizer and a polymer selected from the group consisting of a precursors to an electrically conductive polymer and an electrically conductive polymer.
8. A structure according to claim 7, wherein said conductivity is isotropic.
9. A structure according to claim 7, wherein said polymer is selected from the group consisting of substituted and unsubstituted polyparaphenylene vinylenes, polythianophthenes polyparaphenylenes, polyanilines, polythiophenes, polyazines, polyfuranes, polypyrroles, polyselenophenes, poly-p-phenylene sulfides, polyacetylenes formed from soluble precursors, combinations thereof and blends thereof with other polymers and copolymers of the monomers thereof.
10. A structure according to claim 7, wherein said plasticizer is selected from the group consisting of:
Adipic acid derivatives Sebacic acid derivatives Azelaic acid derivatives Stearic acid derivatives Benzoic acid derivatives Succinic acid derivatives Citric acid derivatives Sulfonic acid derivative Dimer acid derivatives Terpentines Epoxy derivatives Terpentine derivatives Fumaric acid derivatives Siloxanes Glycerol derivatives Polysiloxanes Isobutyrate derivatives Ethylene glycols Isophthalic acid derivatives Polyethylene glycols Lauric acid derivatives Polyesters Linoleic acid derivative Sucrose derivatives Maleic acid derivative Tartaric acid derivative Mellitates Terephthalic acid derivative Myristic acid derivatives Trimellitic acid derivatives Oleic acid derivatives Glycol derivatives Palmitic acid derivatives Glycolates Paraffin derivatives Hydrocarbons Phosphoric acid derivatives Phosphonic acid derivatives Phthalic acid derivatives Polysilanes Ricinoleic acid derivatives
11. A structure comprising a polyaniline material having at least one crystal grain, said material having isotropic electrical conductivity.
12. A structure comprising a non-stretch oriented electrically conductive polyanaline material having at least one crystalline region.
13. A structure comprising a plasticized polymer material selected from the group consisting of a precursor to an electrically conductive polymer and an electrically conductive polymer.
14. A structure comprising an antiplasticized polymer material selected from the group consisting of a precursor to an electrically conductive polymer and an electrically conductive polymer.
15. A structure according to claim 1, wherein said at least one crystalline region is greater than about 80 Å.
16. A structure according to claim 11, wherein said crystalline region is greater than about 80 Å.
17. A structure according to claim 7, wherein said structure has at least one crystalline region of greater than about 80 Å.
18. A structure comprising a polyaniline material having at least one crystal grain and an amorphous material containing an additive in an amount from about 0.001% to about 90% be weight;
said additive is selected from the group consisting of poly-co-dimethylaminopropyl siloxane, poly(ethylene glycol) tetrahydron furfuryo ether, glycerol triacetate and epoxidized soy bean oil.
19. A structure comprising a polysiloxane and a polymer selected from the group consisting of a precursor to an electrically conductive polyaniline and an electrically conductive polyaniline.
20. A structure according to claim 18, wherein said polysiloxane is poly-co-dimethylaminopropryl siloxane.
21. A structure according to claim 7, wherein said plasticizer is selected from the group consisting of monomers, oligomeric and polymeric plasticizers.
22. A structure according to claim 7, wherein said plasticizer interacts with said polymer by interactions selected from the group consisting of hydrogen bonding, dipolar interactions, electrostatic interactions, Vander Waal interactions and palar groups on said plasticizer.
23. A structure according to claim 7, wherein said structure is thermally annealed.
24. A structure according to claim 7, wherein said additive is m-cresol.
25. A structure according to claim 7, wherein said structure has metallic island size greater than about 200 Å.
26. A polyaniline material having at least one crystal having an interchain registration greater than that of a stretch oriented film.
Description
CROSS REFERENCE TO RELATED APPLICATION

[0001] U.S. patent application Ser. No. ______ entitled, “METHODS OF FABRICATING PLASTICIZED, ANTIPLASTICIZED AND CRYSTALLINE CONDUCTING POLYMERS AND PRECURSORS THEREOF” and U.S. patent application Ser. No. ______ entitled, “POLYCRYSTALLINE CONDUCTING POLYMERS AND PRECURSORS THEREOF HAVING ADJUSTABLE MORPHOLOGY AND PHYSICAL PROPERTIES” the teachings of which are incorporated herein by reference.

[0002] This application claims priority from Provisional Application Serial No. 60/007,688 filed Nov. 29, 1995.

FIELD OF THE INVENTION

[0003] The present invention is directed to crystalline electrically conductive polymer precursors and crystalline conducting polymers and applications thereof.

BACKGROUND

[0004] Electrically conductive organic polymers emerged in the 1970's as a new class of electronic materials. These materials have the potential of combining the electronic and magnetic properties of metals with the light weight, processing advantages, and physical and mechanical properties characteristic of conventional organic polymers. Examples of electrically conducting polymers are polyparaphenylene vinylenes, polyparaphenylenes, polyanilines, polythiophenes, polyazines, polyfuranes, polythianaphthenes polypyrroles, polyselenophenes, poly-p-phenylene sulfides, polyacetylenes formed from soluble precursors, combinations thereof and blends thereof with other polymers and copolymers of the monomers thereof.

[0005] These polymers are conjugated systems which are made electrically conducting by doping. The doping reaction can involve an oxidation, a reduction, a protonation, an alkylation, etc. The non-doped or non-conducting form of the polymer is referred to herein as the precursor to the electrically conducting polymer. The doped or conducting form of the polymer is referred to herein as the conducting polymer.

[0006] conducting polymers have potential for a large number of applications in such areas such as electrostatic charge/discharge (ESC/ESD) protection, electromagnetic interference (EMI) shielding, resists, electroplating, corrosion protection of metals, and ultimately metal replacements, i.e. wiring, plastic microcircuits, Conducting pastes for various interconnection technologies (solder alternative), etc. Many of the above applications especially those requiring high current capacity have not yet been realized because the conductivity of the processible conducting polymers is not yet adequate for such applications.

[0007] To date, polyacetylene exhibits the highest conductivity of all the conducting polymers. The reason for this is that polyethylene can be synthesized in a highly crystalline form (crystallinity as high as 90% has been achieved) (as reported in Macromolecules, 25, 4106, 1992). This highly crystalline polyacetylene has a conductivity on the order of 10 5 S/cm. Although this conductivity is comparable to that of copper, polyacetylene is not technologically applicable because it is a non-soluble, non-processible, and environmentally unstable polymer.

[0008] The polyaniline class of conducting polymers has been shown to be probably the most suited of such materials for commercial applications. Great strides have been made in making the material quite processable. It is environmentally stable and allows chemical flexibility which in turn allows tailoring of its properties. Polyaniline coatings have been developed and commercialized for numerous applications. Devices and batteries have also been constructed with this material. However, the conductivity of this class of polymers is generally on the low end of the metallic regime. The conductivity is on the order of 100 S/cm. Some of the other soluble conducting polymers such as the polythiophenes, poly-para-phenyleneviniylenes exhibit conductivity on the order of 102 S/cm. It is therefore desirable to increase the conductivity of the soluble/processible conducting polymers, in particular the polyaniline materials.

[0009] The conductivity (σ) is dependent on the number of carriers (n) set by the doping level, the charge on the carriers (q) and on the interchain an intrachain mobility (μ) of the carriers.

σ=n q μ:

[0010] Generally, n (the number of carriers) in these systems is maximized and thus, the conductivity is dependent on the mobility of the carriers. To achieve higher conductivity, the mobility in these systems needs to be increased. The mobility, in turn, depends on the morphology of the polymer. The intrachain mobility depends on the degree of conjugation along the chain, presence of defects, and on the chain confirmation. The interchain mobility depends on the interchain interactions, the interchain distance, the degree of crystallinity, etc. Increasing the crystallinity results in increased conductivity as exemplified by polyacetylene. To date, it has proven quite difficult to attain polyaniline in a highly crystalline state. Some crystallinity has been achieved by stretch orientation or mechanical deformation (A. G. MacDiarmid et al in Synth. Met. 55-57, 753). In these stretch-oriented systems, conductivity enhancements have been observed. The conductivity enhancement was generally that measured parallel to the stretch direction. Therefore, the conductivity in these systems is an isotropic. It is desirable to achieve a method of controlling and tuning the morphology of polyaniline. It is desirable to achieve a method of controlling and tuning the degree of crystallinity and the degree of amorphous regions in polyaniline, which in turn provides a method of tuning the physical, mechanical, and electrical properties of polyaniline. It is further desirable to achieve highly crystalline and crystalline polyaniline and to achieve this in a simple and useful manner in order to increase the mobility of the carriers and, therefore, the conductivity of the polymer. It is also further desirable to achieve isotropic conductivity, that is conductivity not dependent on direction as with stretch-orientated polyanilines.

OBJECTS

[0011] It is an object of the present invention to provide an electrically conducting polymer precursor and electrically conducting polymer having an adjustable morphology.

[0012] It is an object of the present invention to provide an electrically conductive polymer precursor and electrically conducting polymer in which the degree of amorphous and crystalline regions is adjustable.

[0013] It is an object of the present invention to provide an electrically conducting polymer precursor and electrically conducting polymer having adjustable physical, mechanical, and electrical properties.

[0014] It is an object of the present invention to provide a crystalline electrically conducting polymer precursor and crystalline conducting polymers

[0015] It is an object of the present invention to provide a highly crystalline electrically conducting polymer precursor and highly crystalline conducting polymers

[0016] It is another object of the present invention to provide an electrically conducting polymer that exhibits enhanced carrier mobility.

[0017] It is another object of the present invention to provide an electrically conducting polymer which exhibits enhanced conductivity.

[0018] It is another object of the present invention to provide an electrically conducting polymer which exhibits enhanced isotropic conductivity.

[0019] It is another object of the present invention to provide a plasticization effect in electrically conducting polymer precursors and electrically conducting polymers.

[0020] It is another object of the present invention to provide an antiplasticization effect in electrically conducting polymer precursors and electrically conducting polymers.

[0021] It is another object of the present invention to provide a precursor or electrically conducting polymer containing an additive providing mobility.

[0022] It is another object of the present invention to provide a precursor or electrically conductive polymer containing an additive to induce an enhanced degree of crystallinity.

[0023] It is another object of the present invention to provide a non-strench oriented film of a precursor or of an electrically conductive polymer which has an enhanced degree of crystallinity.

[0024] It is an object of the present invention to provide an electrically conducting polymer precursor and electrically conducting polymer having an increased glass transition temperature.

[0025] It is an object of the present invention to provide an electrically conducting polymer precursor and electrically conducting polymer having an decreased glass transition temperature.

[0026] It is an object of the present invention to provide an electrically conducting polymer precursor and electrically conducting polymer having enhanced mechanical properties.

[0027] It is an object of the present invention to provide an electrically conducting polymer precursor and electrically conducting polymer having decreased mechanical properties.

SUMMARY OF THE INVENTION

[0028] 1. (SUMMARY) A broad aspect of the present invention is a structure having an admixture of an additive and a polymer selected from the group consisting of a precursor to an electrically conductive polymer and an electrically conductive polymer wherein the additive provides local mobility to the polymer to allow the polymer chains to closely associate with one another to achieve a highly crystalline state.

[0029] In a more particular aspect of the present invention is a structure having an admixture of an additive and a polymer selected film the group consisting of a precursor to an electrically conductive polymer and an electrically conductive polymer wherein the additive provides a plasticization effect.

[0030] In a more particular aspect of the present invention is a structure having an admixture of an additive and a polymer selected film the group consisting of a precursor to an electrically conductive polymer and an electrically conductive polymer wherein the additive provides an antiplasticization effect.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further objects, features, and advantages of the present invention will become apparent from a consideration of the following detailed description of the invention when read in conjunction with the drawings FIG's. in which:

[0032]FIG. 1 is a general formula for polyaniline in the non-doped or precursor form.

[0033]FIG. 2 is a general formula for a doped conducting polyaniline.

[0034]FIG. 3 is a general formula for the polysemiquinone radical cation form of doped conducting polyaniline.

[0035]FIG. 4 is a Gel Permeation Chromatography (GPC) of polyaniline base in NMP (0.1%). GPC shows a tripodal distribution—A very high molecular weight fraction (approx. 12%) and a major peak having lower molecular weight.

[0036] Curve 5(a) is a Wide Angle X-Ray Scattering (WAXS) spectrum for a polyaniline base film processed from NMP. The polymer film is essentially amorphous. Curve 5(b) is a Wide Angle X-Ray Scattering spectrum for a polyaniline base film that has been stretch-oriented (1/lo=3.7). This film was derived from a gel. Curve 5(c) is a Wide Angle X-Ray Scattering spectrum for a polyaniline base film containing 10% of poly-co-dimethyl propylene siloxane. This film is highly crystalline.

[0037]FIG. 6 is a Schematic diagram of a polycrystalline material as taught in present invention having crystalline regions (outlined in dotted rectangles) with intersticial amorphous regions

[0038]FIG. 7 is a Dynamic Mechanical Thermal Analysis (DMTA) plot for polyaniline base film cast from NMP. (First Thermal Scan; under Nitrogen).

[0039]FIG. 8 is a DMTA plot which represents the second thermal scan for a polyaniline base film cast from NMP; This same film was previously scanned as shown in FIG. 7. Film Contains no residual solvent.

[0040]FIG. 9 is a DMTA plot for polyaniline base film cast from NMP and containing 5% poly-co-dimethyl aminopropyl siloxane (5% N content). First Thermal Scan.

[0041]FIG. 10 is a DMTA plot for polyaniline base film cast from NMP and containing 5% poly-co-dimethyl aminopropyl siloxane (5% N content). Second Thermal Scan (this same film was previously scanned as shown in FIG. 9) Film Contains no residual solvent.

[0042]FIG. 11 is a GPC for a polyaniline base solution in NMP containing 5% poly-co-dimethyl aminopropyl siloxane by weight to polyaniline. The polyaniline was 0.1% in NMP.

DETAILED DESCRIPTION

[0043] The present invention is directed toward electrically conducting polymer precursors and conducting polymers having adjustable morphology and in turn adjustable physical, mechanical, and electrical properties. The present invention is also directed toward controlling and enhancing the 3-dimensional order or crystallinity of conducting polymer precursors and of conducting polymers. In addition, the present invention is directed towards enhancing the electrical conductivity of conducting polymers. This is done by forming an admixture of an electrically conducting polymer precursor or an electrically conducting polymer with an additive whereby the additive provides local mobility to the molecules so as to allow the conducting polymer precursor or conducting polymer chains to associate with one another and achieve a highly crystalline state. An example of such an additive is a plasticizer. A plasticizer is a substance which when added to a polymer, solvates the polymer and increases its flexibility, deformability, generally decreases the glass transition temperature Tg, and generally reduces the tensile modulus. In certain cases, the addition of a plasticizer may induce antiplasticization, that is an increase in the modulus or stiffness of the polymer, an increase in Tg. Herein the additives can provide a plasticization effect, an antiplasticization effect or both effects.

[0044] Examples of polymers which can be used to practice the present invention are of substituted and unsubstituted homopolymers and copolymers of aniline, thiophene, pyrrole, p-phenylene sulfide, azines, selenophenes, furans, thianaphthenes, phenylene vinylene, etc. and the substituted and unisubstituted polymers, polyparaphenylenes, polyparaphenylevevinylenes, polyaniliines, polyazines, polythiophenes, poly-p-phenylene sulfides, polyfuranes, polypyrroles, polythianaphthenes, polyselenoplhenes, polyacetylenes formed from soluble precursors and combinations thereof and copolymers of monomers thereof. The general formula for these polymers can be found in U.S. Pat. No. 5,198,153 to Angelopoulos et al. While the present invention will be described with reference to a preferred embodiment, it is not limited thereto. It will be readily apparent to a person of skill in the art how to extend the teaching herein to other embodiments. One type of polymer which is useful to practice the present invention is a substituted or unsubstituted polyaniline or copolymers of polyaniline having general formula shown in FIG. 1 wherein each R can be H or any organic or inorganic radical; each R can be the same or different; wherein each R1 can be H or any organic or inorganic radical, each R1 can be the same or different; x≧1; preferable x≧2 and y has a value from 0 to 1. Examples of organic radicals are alkyl or aryl radicals. Examples of inorganic radicals are Si and Ge. This list is exemplary only and not limiting. The most preferred embodiment is emeraldine base form of the polyaniline wherein y has a value of approximately 0.5. The base form is the non-doped form of the polymer. The non-doped form of polyaniline and the non-doped form of the other conducting polymers is herein referred to as the electrically conducting polymer precursor.

[0045] In FIG. 2, polyaniline is shown doped with a dopant. In this form, the polymer is in the conducting form. If the polyaniline base is exposed to cationic species QA, the nitrogen atoms of the imine (electron rich) part of the polymer becomes substituted with the Q+ cation to form an emeraldine salt as shown in FIG. 2. Q+ can be selected from H+ and organic or inorganic cations, for example, an alkyl group or a metal.

[0046] QA can be a protic acid where Q is hydrogen. When a protic acid, HA, is used to dope the polyaniline, the nitrogen atoms of the imine part of the polyaniline are protonated. The emeraldine base form is greatly stabilized by resonance effects. The charges distribute through the nitrogen atoms and aromatic rings making the imine and amine nitrogens indistinguishable. The actual structure of the doped form is a delocalized polysemiquinone radical cation as shown, in FIG. 3.

[0047] The emeraldine base form of polyaniline is soluble in various organic solvents and in various aqueous acid solutions. Examples or organic solvents are dimethylsulfoxide (DMSO), dimethylformamide (DMF) and N-methylpyrrolidinone (NMP), dimethylene propylene urea, tetramethyl urea, etc. This list is exemplary only and not limiting. Examples of aqueous acid solutions is 80% acetic acid and 60-88% formic acid. This list is exemplary only and not limiting.

[0048] Polyaniline base is generally processed by dissolving the polymer in NMP. These solutions exhibit a bimodal or tripodal distribution in Gel Permeation Chromatography (GPC) as a result of aggregation induced by internal hydrogen bonding between chains as previously described in U.S. patent application Ser. No. 08/370,128, filed on Jan. 9, 1995, the teaching of which is incorporated herein by reference. The GPC curve for typical polyaniline base in NMP is shown in FIG. 4.

[0049] Polymers in general can be amorphous, crystalline, or partly crystalline. In the latter case, the polymer consists of crystalline phases and amorphous phases. The morphology of a polymer is very important in determining the polymer's physical, mechanical, and electronic properties.

[0050] Polyaniline base films processed from NMP either by spin-coating or by solution casting techniques are amorphous as can be seen in FIG. 5a which depicts the Wide Angle X-Ray Scattering (WAXS) spectrum for this material. Amorphous diffuse scattering is observed. Some crystallinity is induced in these films by post processing mechanical deformation especially if these films are derived from gels as described by A. G. MacDiarmid et al in Synth. Met. 55-57, 753 (1993). WAXS of a stretch oriented film having been stretched (1/lo=3.7×) derived from a gel is shown in FIG. 5b. Some crystallinity has been induced as compared to the non-stretch oriented films as evidenced by the defined scattering peaks.

[0051] Doping the amorphous polyaniline base films (those having structure shown in FIG. 5a) with aqueous hydrochloric acid results in isotropic conductivity of 1 S/cm. Such films are not crystalline. Similar doping of stretch oriented films results in an isotropic conductivity where conductivity on the order of 102 S/cm is measured parallel to the stretch direction whereas conductivity on the order of 100 S/cm is measured perpendicular to the stretch direction. It should also be noted that some level of crystallinity is lost during the doping process in these films.

[0052] According to the present invention, the interchain (polymer chain) registration is increased as compared to a stretch oriented film.

[0053]FIGS. 7 and 8 show the dynamic mechanical thermal analysis (DMTA) spectrum for a polyaniline base film processed from NMP alone. FIG. 7 is the first scan where a Tg of approx. 118 is observed as a result of the residual NMP which is present in the film. FIG. 8 is the second thermal scan of the same film. This film has no residual solvent and a Tg of ≅251° C. is measured for the polyaniline base polymer.

[0054] When an additive such as a plasticizer, such as a poly-co-dimethyl propylamine siloxane, is added to the polyaniline base completely different properties and morphology is observed. The siloxane has a polar amine group which facilitates the miscibility of the polyaniline base and the plasticizer. The DMTA of a polyaniline base film cast from NMP and containing 5% by weight to polyaniline of the poly-co-dimethyl propyl amine siloxane exhibits a lower Tg on the first thermal scan as compared to polyaniline base processed from NMP alone (FIG. 9) as a result of plasticization induced by the siloxane. However, on the second thermal scan of this film (FIG. 10), the polymer exhibits an increase in Tg as compared to polyaniline processed from NMP. When the polysiloxane is added to a solution of polyaniline base, the siloxane due to the polar amine group can interact with the polymer chains and disrupt some of the polyaniline interactions with itself or some of the aggregation. Thus, the polysiloxane first induces some deaggregation. However, the polysiloxane has multiple amine sites and thus, it can itself hydrogen bond with multiple polyaniline base chains and thus, the polysiloxane facilitates the formation of a cross-linked network. This cross-linked network accounts for the increased Tg observed in the DMTA. Tg is characteristic of the amorphous regions of a polymer and in this case the amorphous regions consist of a cross-linked polyaniline/polysiloxane network. Thus, the polysiloxane is inducing an antiplasticization effect in polyaniline base as the Tg is increased. Generally, plasticizers reduce Tg. GPC data (FIG. 11) is consistent with this model. The addition of the poly-amino containing siloxane to a polyaniline base solution in NMP results in a significant increase in the high molecular weight fractions depicting the cross-linked network which forms between polyaniline and the plasticizer.

[0055] In addition to the cross-linked network the siloxane induces in the amorphous regions, concomittantly it also is found to induce significant levels of crystallinity in polyaniline base as a result of the local mobility that it provides. FIG. 5c shows the WAXS for a polyaniline base film processed from NMP containing 10% of the poly amino containing siloxane. As can be seen highly crystalline polyaniline has been attained. Much higher levels of crystallinity as compared to FIG. 5b for the stretch oriented films.

[0056] Thus polyaniline by the addition of the siloxane forms a structure depicted in FIG. 6 where crystalline regions of highly associated polyaniline chains (outlined by a rectangle) are formed with intersticial amorphous regions. In most cases, the additive resides in the amorphous intersticial sites. The degree of crystallinity (number of Crystalline sites) and the size of the crystalline domains as well as the degree of amorphous regions and the nature of the amorphous region (aggregated, i.e. cross-linked or not) can be tuned by the type and amount of additive. In turn, by controlling the above, the properties of the material can also be controlled.

[0057] With the poly-co-dimethyl aminopropyl siloxane (5% N content), loadings ranging from 0.001 to 20% by weight gives highly crystalline polyaniline. The highly crystalline polyaniline in turn exhibits increased modulus, stiffness, yield and tensile strengths, hardness, density and softening points. Thus, the siloxane at these loadings is having an antiplasticization effect. Above 20% loading, the crystallinity begins to decrease. As the crystallinity decreases, the modulus, stiffness, yield and tensile strengths, hardness, density and softening points begin to decrease. Thus, the siloxane at these loadings begins to have a plasticization effect. The siloxane content becomes high enough that it disrupts the polyaniline base interactions in the crystalline regions. With the poly co dimethyl aminopropyl siloxanes having 0.5 and 13% N ratios, similar trends are observed but the particular amount of siloxane needed to have a plasticization effect or an antiplasticization effect varies. Thus, the degree of crystallinity and the degree of amorphous regions and in turn the properties of polyaniline can be tuned by the nature of the additive as well as the amount of additive. Indeed, using the same additive but simply changing the loading dramatically changes the morphology and in turn the properties of polyaniline.

[0058] The electronic properties of the polymer are also impacted. The conductivity of a polyaniline base film cast from NMP and containing 1% by weight poly-co-dimethyl aminopropyl siloxane which is doped by aqueous hydrochloric acid is 50 S/cm as compared to 1 S/cm for a polyaniline film with no plasticizer. This is isotropic conductivity. The doped film containing the polysiloxane retains the highly crystalline structure.

[0059] The degree of crystallinity and the degree of amorphous regions and in turn the physical, mechanical, and electronic properties can be tuned by the particular additive used and by the amount of additive. For example, the Tg of polyaniline can be increased or decreased by the amount and type of additive. The mechanical properties such as tensile properties, modulus, impact resistance, etc. can be tuned as described above. The additive can range from 0.001 to 90% by weight, more preferably from 0.001 to 50% and most preferably from 0.001 to 25%. A list of plasticizers that can be used to practice the present invention is given in Table 1. The plasticizer can be small molecules, oligomeric or polymeric in nature as can be seen in Table 1. They can be monofuntional, bifunctional, and multifunctional. The additive can also be removed from the final film structure if so desired by appropriate extraction.

SPECIFIC EXAMPLES

[0060] Polyaniline Synthesis Polyaniline is synthesized by the oxidative polymerization of aniline using ammonium peroxydisulfate in aqueous hydrochloric acid. The polyaniline hydrochloride precipitates film solution. The polymer is then neutralized using aqueous ammonium hydroxide. The neutralized or non-dope polyaniline base is then filtered, washed and dried. Polyaniline can also be made by electrochemical oxidative polymerization as taught by W. Huang, B. Humphrey, and A. G. MacDiarmid, J. Chem. Soc., Faraday Trans. 1, 82, 2385, 1986.

[0061] Polyaniline Base in NMP: The polyanilines base powder is readily dissolved in NMP up to 5% solids. Thin films (on the order of a micron) can be formed by spin-coating. Thick films are made by solution casting and drying (70° C. in vacuum oven under a nitrogen purge for 15 hours). These solutions and films have the properties described above.

Polyaniline Base in NMP/Plasticizer

[0062] a. Polyaniline Base was first dissolved in NMP to 5% solids and allowed to mix well. A poly-co-dimethyl, aminopropyl siloxane (N content 5% relative to repeat unit) was dissolved to 5% in NMP. The siloxane solution was added to the polyaniline base solution. The resulting admixture was allowed to mix for 12 hours at room temperature. A number of solutions were made having from 0.001% to 50% siloxane content (by weight relative to polyaniline). Thin films were spin-coated onto quartz substrates; Thick films were prepared by solution casting and baking the solutions at 70° C. in a vacuum oven under a Nitrogen purge for 15 hours). The solutions and the films have the properties described above.

[0063] b. The same experiment described in (a) was carried out except that the plasticizer was a poly-co-dimethyl, aminopropyl siloxane in which the N content was 13%.

[0064] c. The same experiment described in (a) was carried out except that the plasticizer was a poly-co-dimethyl, aminopropyl siloxane in which the N content was 0.5%.

[0065] d. The same experiment described in (a) was carried out except that the plasticizer was polyglycol diacid.

[0066] e. The same experiment described in (a) was carried out except that the plasticizer was 3,6,9-trioxaundecanedioic acid.

[0067] f. The same experiment described in (a) was carried out except that the plasticizer was poly(ethylene glycol) tetrahydron furfuryl ether.

[0068] g. The same experiment described in (a) was carried out except that the plasticizer was glycerol triacetate.

[0069] h. The same experiment described on (a) was carried out except the plasticizer was epoxidized soy bean oil.

Polyaniline Base in NMP/m-Cresol/Plasticizer

[0070] The same experiment as described in (a) was carried out except that polyaniline base and the plasticizer was dissolved in NMP/m-Cresol mixtures in which m-Cresol ranged from 1 to 99%

Polyaniline Base in m-Cresol/Plasticizer

[0071] The same experiment as described in (a) was carried out except that the polyaniline base was dissolved in m-Cresol and the plasticizer was dissolved in m-Cresol.

Polyaniline Base in m-Cresol and in NMP/m-Cresol

[0072] Polyaniline Base was dissolved in m-Cresol and in NMP/m-Cresol combinations to 5% solids. The m-Cresol in the latter system being the additive ranged from 1 to 99%. Free-Standing films were made by solution-casting techniques. With increasing m-cresol content, the polyaniline exhibited a WAXS similar to that shown in FIG. 5a except that the amorphous scattering peak became somewhat sharper indicative of some crystallinity. However, this was significantly less than observed with the siloxane plasticizer.

Doped Polyanilines

[0073] 1. Hydrochloric Acid and/or Methanesulfonic Acid Doped Films

[0074] Polyaniline base films made as described above were doped by aqueous acid solutions of hydrochloric or methanesulfonic acid. The films were immersed in the acid solution for 12 hours for thin films and 36 hours for the thick films. The conductivity of a polyaniline base film processed from NMP and doped with these acid solutions is 1 S/cm. The conductivity of a base film processed from NMP and 1% poly-co-dimethyl, aminopropyl siloxane (5% N content) was 50 S/cm.

[0075] 2. Sulfonic Acid Doped Polyanilines

[0076] Polyaniline Base was dissolved in a solvent such as NMP or NMP/m-Cresol combinations, etc. from 1 to 5% solids. To this solution was added a dopant such as camphorsulfonic acid or acrylamidopropanesulfonic acid (previously reported in U.S. patent application Ser. No. 595,953 filed on Feb. 2, 1996). These solutions were used to spin-coat or solution cast films. In some experiments, the plasticizer such as the poly-co-dimethyl,aminopropyl siloxane in a solvent was added to the doped polyaniline solution. In certain other experiments, the plasticizer was first added to the pani base solution. The dopant was then added to the polyaniline solution containing the plasticizer.

[0077] The teaching of the following U.S. Patent Applications are incorporated herein by reference:

[0078] “CROSS-LINKED ELECTRICALLY CONDUCTIVE POLYMERS, PRECURSORS THEREOF AND APPLICATIONS THEREOF”, application Ser. No. 595,853, filed Feb. 2, 1996;

[0079] “METHODS OF FABRICATION OF CROSS-LINKED ELECTRICALLY CONDUCTIVE POLYMERS AND PRECURSORS THEREOF”, application Ser. No. 594,680, filed Feb. 2, 1996;

[0080] “DEAGGREGATED ELECTRICALLY CONDUCTIVE POLYMERS AND PRECURSORS THEREOF”, application Ser. No. 370,127, filed Jan. 9, 1995; and

[0081] “METHODS OF FABRICATION OF CROSS-LINKED ELECTRICALLY CONDUCTIVE POLYMERS AND PRECURSORS THEREOF”, application Ser. No. 370,128, filed Jan. 9, 1995.

[0082] While the present invention has been shown and described with respect to a preferred embodiment, it will be understood that numerous changes, modifications, and improvements will occur to those skilled in the art without departing from the spirit and scope of the invention.

Classifications
U.S. Classification252/500
International ClassificationC08L71/02, C08K5/09, H01B1/12, C08L79/00, C08L101/00, C08K5/10, C08K5/42, C08K5/28, C08L83/04, C08K5/5419, C08G61/12, C08K5/103
Cooperative ClassificationH01B1/128, C08G61/12
European ClassificationC08G61/12, H01B1/12H6
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