WO1999017929A1

WO1999017929A1 - Polymeric electrostrictive systems

Info

Publication number: WO1999017929A1
Application number: PCT/US1998/021034
Authority: WO
Inventors: Qiming Zhang; Alan G. Macdiarmid; Ji Su; Pen-Cheng Wang; Kenneth J. Wynne
Original assignee: The Trustees Of The University Of Pennsylvania
Priority date: 1997-10-03
Filing date: 1998-10-02
Publication date: 1999-04-15

Abstract

The present invention generally describes all-polymer electrostrictive systems. In the systems, a conductive polymer is directly deposited onto opposing surfaces of a thermoplastic polymer elastomer film. Due to its flexibility, strong coherent interfaces and significantly improved acoustic transparency and reduced clamping effect, the all-polymer electrostrictive system may improve the performance of electromechanical polymer materials in acoustic applications.

Description

POLYMERIC ELECTROSTRICTIVE SYSTEMS

Government Support

Portions of the technology disclosed herein may have been supported by the Office of Naval Research through grant numbers NOOO 14-96- 1-0418 and N00014- 92-J-1369.

Field of the Invention

The present invention generally describes all-polymer electrostrictive systems. In the systems, a soft conductive polymer is directly deposited onto opposing surfaces of a thermoplastic polymer elastomer film by an adsorption polymerization method. Due to its flexibility, strong coherent interfaces and significantly improved acoustic transparency, the all-polymer electrostrictive system may improve the performance of electromechanical polymer materials in acoustic applications.

Background of the Invention. Recent studies on electromechanical properties of polymers have shown that some thermoplastic polymer elastomers, especially segmented polyurethane elastomers, can exhibit very high electric field induced strain responses. See Zhenyi et al, J Polym. Sci. Part B: Polym. Phys., 32:2721 (1994). As promising materials for application in transducer, sensor and actuator technologies (see Herbert, Ferroelectric Transducers and Sensors, Gordon and Breach Science Publishers, New York (1982)), these electromechanically-active polyurethane elastomers have drawn increasingly greater attention and many experimental investigations have been conducted since the large electric field induced strain found in this class of polyurethane elastomers was reported. See, Wang et al, Proc. Int. Symp. Appl. Ferro., 9:182 (1994); Wang, Ph.D. Thesis, The Pennsylvania State University, 1994; Su et al, J. Appl. Polym. Sci., 65:1363 (1997); Su et al, Proc. Int. Symp. Appl. Ferro. 10:927 (1996); Zhang et al, J. Appl. Phys., 81 :2770 (1997); Su et a.1, Appl. Phys. Lett. 71 :386 (1997).

Increased interest in using electroactive polymeric materials for electro- acoustic and electromechanical applications also raises the issue of new electrode materials to meet requirements such as high acoustic transparency, very small acoustic impedance mismatching reduced mechanical clamping and fatigue effects. The present invention is directed to these, as well as other, important ends.

Summary of the Invention

The present invention generally describes all-polymer electromechanical systems. In the systems, a soft conductive polymer, such as doped polypyrrole, is directly deposited onto opposing surfaces of thermoplastic polymer elastomer film, such as polyurethane, by an adsorption polymerization method. The conductive polymer electrodes replace conventionally-used metal electrodes, such as Al, Ag, Au and the like. Using the technique developed in the present invention, the conductive polymer electrode exhibits strong coherent interfaces. The match of the acoustic impedance of the conductive polymer electrode with that of electromechanical polymers, such as polyurethane, significantly improves the acoustic transparency, which may improve the performance of electromechanical polymer materials in acoustic and ultrasonic applications. For the effect of the interface boundary layer acoustic impedance mismatch on the transducer performance, see Kino, Acoustic Waves: Devices, Imaging and Analog Signal Processing, Chapter 1, Prentice-Hall, Inc., NJ (1987); Silk, Ultrasonic Transducers for Nondestructive Testing, Adam Hilger Ltd., Bristol (1984).

For soft polymers, such as polyurethane, metal electrodes such as Au and Al impose mechanical clamping on the polymer which can significantly reduce the electrical field induced strain level and hence, the efficiency of the electromechanical transduction. With conducting polymer electrodes, due to their low elastic modulus, the clamping effect is reduced markedly which again improves the performance of electromechanical polymers. See, Su et al, Appl. Phys. Lett., 71:386 (1997). In addition, metal electrodes suffer fatigue and fracture due to the large strain (>2%) induced from change in dimensions of the polymer substrate to which they are attached, leading to disfunction of the electrode. Conductive polymers can withstand such a strain level (2%-5%) without electrical disfunction. See Wynne and Street, Macromolecules, 18:2361 (1985); Yamaura et al., Synth. Met, 26:209 (1988); Su et al., Polym. Adv. Technol, 9:317 (1998). This feature is essential for any practical acoustic devise utilizing larger strain levels.

The present invention deals with the mechanical strain in polymeric materials induced by an external electric field for application in electromechanical transduction, such as in naval underwater sonar and medical ultrasonic transducers. In the present invention, the dielectric and electric field induced strain properties of the films are characterized. The temperature dependence of the dielectric properties shows the conductive polymer electrode is appropriately functional, and the thickness and frequency dependence of the electric field induced strain responses in the composite films show characteristics similar to those of films with gold electrodes under identical experimental conditions.

These, as well as other aspects of the present invention will become apparent from the following detailed description.

Brief Description of the Drawings Figures 1A-C are schematic diagrams of the procedure for direct deposition of conductive polymer onto the surfaces of the solution-cast electrostrictive polyurethane elastomer films. Figure 1A is a solution-cast film of polyurethane on a glass substrate. Figure IB is the apparatus for the direct deposition of a conductive polymer onto the opposing surfaces of a polyurethane film. Figure 1C is a polyurethane film with conductive polypyrrole on opposing surfaces.

Figure 2 is a comparison of the dielectric constant and dielectric loss of conductive polymer-electroded and gold-electroded solution-cast polyurethane films as a function of temperature at 100 Hz.

Figure 3 is a comparison of the electric field induced strain coefficient, R, of the conductive polymer-electroded and gold-electroded solution-cast polyurethane films with thicknesses of 0.1 mm and 0.2 mm, respectively, as a function of frequency. The solid lines are drawn to guide the eye.

Figures 4A-B show the thickness dependence of the electric field induced strain coefficient, R, of the conductive polymer-electroded polyurethane films (Figure 4A) and the gold-electroded polyurethane films (Figure 4B) at various frequencies. The solid lines are drawn to guide the eye.

Detailed Description of the Invention

The present invention generally describes all-polymer electrostrictive films which may be produced by directly depositing conductive polymers onto opposing sides of an electrostrictive thermoplastic polymer elastomer film such as polyurethane. The conductive polymer may be the same on either side of the elastomer film, or different. The final composite films are flexible with strong adhesion between the thermoplastic polymer elastomer film and the conductive polymer electrode. The conductivity (sheet resistivity is about 1,000 Ω/π) of the polymer electrode is appropriate for its intended use as, for example, acoustic and ultrasonic transducers.

Conductive polymers that may be used in the present invention include, but are not limited to, doped polypyrrole and its doped derivatives, doped polyaniline and its doped derivatives, and doped polythiophene and its doped derivatives. In general, all anionic chemical species can be incorporated into the conductive polymers as dopant anions as long as the whole doped conductive polymer system can remain electroactive as electrodes in a stable and compatible state. The doped conductive polymers are prepared following conventional methods that are well-known in the art. Preferably, the dopant anions for use in the present invention include, but are not limited to, Br, Cl\ P, ClO₄ ^", PF₆\ AsF₄\ AsF₆\ SO₃CF₃ ^", BF₄\ BC1₄ ^", VO₃ ^", PF₆\ POF₄-, CN^", SiF₆ ^", CH₃CO₂- (acetate), C₆H₅CO₂- (benzoate), CH₃C₆H₄SO₃ ^" (tosylate), SO₄ ^2" or the like. Also, suitable dopant anions include, for example, those derived from sulfonic acids and polymeric acids such as benezenesulfonic acid, naphthalenesulfonic acid, dodecyl sulfonic acid, dodecylbenzenesulfonic acid (DBSA),/>-toluenesulfonic acid (PTSA), camphorsulfonic acid (HCSA), 2- acrylamide-2-methyl-l-propanesulfonic acid, and methanesulfonic acid, anthraquinone-2-sulfonic acid, 4,5-dihydroxynaphthalene-2, 7-disulfonic acid, 5- amino-2-naphthalenesulfonic acid, anthraquione-1, 5-disulfonic acid, poly(styrenesulfonic acid) and poly(vinylsulfonic acid).

According to one aspect of the present invention, the conductive polymer is polyaniline, preferably in the emeraldine oxidation state, and its oligomers, such as octamer, wherein the aniline units may be optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C_rC₈ alkyl, C,-C₈ alkenyl, and C_rC₈ alkynyl, wherein the alkyl, alkenyl, and alkynyl substituents are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl and sulfonyl.

In another embodiment of the present invention, the conductive polymer is doped polypyrrole, preferably in or close to an oxidation state from about +0.28 to about +0.32. The pyrrole units are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C_rC₈ alkyl, C_rC₈ alkenyl, and C_rC₈ alkynyl, wherein the alkyl, alkenyl, and alkynyl substituents are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, and sulfonyl. According to another aspect of the present invention, the conductive polymer is doped polythiophene, preferably in or close to an oxidation state of from about +0.25 to about +0.5. The polythiophene units are optionally substituted with at least one of hydroxyl, halo, alkoxyl, amino, cyano, carbonyl, carboxyl, sulfonyl, C_rC₈ alkyl, C,-C₈ alkenyl, and C_rC₈ alkynyl, wherein the alkyl, alkenyl, and alkynyl substituents are optionally substituted with at least one of hydroxyl, halo, alkoxyl, amino, cyano, carbonyl, carboxyl, and sulfonyl. The thiophene units may also be substituted simultaneously in the 3 and 4 positions with a -O-(CH₂)_n-O- group wherein n is 2 or 3.

According to the present invention, electrostrictive thermoplastic polymer elastomer films that may be used include, but are not limited to, polyurethane, poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-trifluoroethylene) copolymers and other electromechanical polymers, such as odd-numbered Nylons.

In the present invention, the compatible interface between the doped polypyrrole electrode polymer and the electrostrictive polyurethane significantly improves the acoustic properties of these composite films as compared to the use of a metal electrode film. Metal electrodes such as Au and Al have an acoustic impedance much higher than that of an electromechanical polymer. For example, metal electrodes have an impedance which is about 30 MRayls while electromechanical polymers such as polyurethane and PVDF have an impedance of less than about 3 MRayls. See, Kino, Acoustic Waves: Devices, Imaging and Analog Signal Processing, Chapter 1, Prentice- Hall, Inc., NJ (1987), which is hereby incorporated by reference. Conductive polymers, unlike metal electrodes, have an acoustic impedance that is nearly the same as that of electromechanical polymers.

Under identical measurement conditions, the electrostrictive characteristics in the all-polymer system of the present invention show similarities to those of a gold electroded system. For example, the all-polymer electrostrictive system exhibits comparable dielectric properties to a gold-electroded system in the temperature range from -40°C to 80°C. This temperature range covers the soft segment glass transition temperature of the polyurethane elastomers, which is about -20 °C. Methods of making the electrostrictive systems of the present invention are described in the examples below.

The electrostrictive system of the present invention also shows large electric field induced strain responses which are dependent on film thickness and measurement frequency. The experimental results, discussed in detail below, indicate the existence of interfacial charge effects in the all-polymer electrostrictive system; however, the effects are not as large as those in the gold-electroded system.

Examples

The following examples are presented for purposes of elucidation and not limitation. The examples are not intended, nor are they to be construed, as limiting the scope of the disclosure or claims.

Example 1

Polyurethane films of various thicknesses (from about 50 micrometers to about 200 micrometers) were produced on a glass substrate by a solution casting method using tetrahydrofuran (THF) as a solvent, followed by annealing at 100° C in a vacuum for 30 minutes. The polyurethane films may also be produced by a hot pressing method, which is known to one skilled in the art.

Thereafter, conductive polymer (i.e., doped polypyrrole) electrodes were deposited on opposing surfaces of the thermoplastic polymer elastomer (i.e., polyurethane) film by an in-situ deposition technique. In-situ deposition techniques are generally described, for example, by Kuhn et al., Synth. Met., 71 :2139 (1995); Manohar et al, Bull. Am. Phys. Soc, 34:582 (1989); and MacDiarmid et al., Mat. Res. Soc. Sypm. Proc, 413:3 (1996), the disclosures of which are hereby incorporated by reference in their entirety. In the present invention, anthraquinone-2-sulfonic acid, sodium salt monohydrate (2.45 g), 5-sulfosalicylic acid dihydrate (13.35 g) and an oxidant such as ferric chloride hexahydrate (FeCl₃-6H₂O) (8.75 g) were dissolved in 250 ml of distilled water. An aqueous solution of pyrrole (1.5 ml dissolved in 250 ml of distilled water) was then added with mild magnetic stirring. Next, polyurethane films fixed on metal frames were immersed in the polymerizing pyrrole solution for a total of 40 minutes permitting in-situ deposition of conductive polypyrrole onto both surfaces of the polyurethane films under ambient laboratory conditions. Generally, the polyurethane films may be immersed in the polymerizing conductive polymer solution for about 3 minutes to about 60 minutes. In order to obtain polypyrrole electrodes with a desirable quality and thickness, the polyurethane films were removed from the polymerizing solution after about 5 to about 10 minutes and were rinsed with distilled water for about 10 seconds. This polymerization-deposition/rinsing procedure was repeated several times during the deposition process. The resultant polypyrrole electrodes were smooth, coherent, and adhered well to the polyurethane films. The final thickness of the polypyrrole electrodes was about 300 A, which was examined using an Alpha-Step^® 500 Surface Profiler (Tencor Instruments). Generally, the film thickness of the conductive polymer electrodes may be in the range of about 200 A to about 1000 A . The film thickness is determined by the desired sheet resistivity of the electrodes for specific transducer applications. The sheet resistivity using the AATCC test method 76-1987 was about 1 ,000 Ω/D. If possible, the sheet resistivity should be about 1 ,000 Ω/D, preferably less than 1,000 Ω/D. A longer dipping time will provide a smaller sheet resistivity.

A schematic diagram of the processing procedure of the polyurethane film with the conductive polymer electrode is shown in Figures 1A-C. Figure 1A is a solution-cast film of polyurethane on a glass substrate which can be removed. Figure IB is an apparatus for the direct deposition of a conductive polymer onto the opposing surfaces of a polyurethane film. Figure 1C is a polyurethane film with conductive polymer electrode (e.g., polypyrrole) on opposing surfaces.

Example 2 The dielectric properties of the polyurethane films with the conductive polymer electrodes were characterized and compared to those of polyurethane films with gold electrodes of the same thickness as the conductive polymer electrodes in the temperature range from -40 °C to 80 °C, as shown in Figure 2. The heating rate used was 2°C/min which was controlled by a LakeShore 321 Autotuning Temperature Controller.

The electric field induced strain coefficient (R)(the electric field induced strain, S, where S=RE², and E is the applied electric field) of the polyurethane films having conductive polymer electrodes was measured as a function of the polyurethane film thickness and frequency at room temperature using a piezoelectric biomorph-based cantilever dilatometer set-up, combined with a lock-in amplifier (Stanford Research System-SR830 DSP) and a high voltage source (KEPCO-BOP 1000M). The thickness and frequency dependence of the strain coefficient of the polymer electrode polyurethane films were compared with those of the films with gold electrodes. The results are presented in Figures 3, 4A and 4B.

Temperature dependence of the dielectric constant and dielectric loss of the polyurethane with conductive polymer electrodes are shown in Figure 2, and are compared with the those of the films with gold electrodes. As can be seen, the two films show very similar characteristics in the temperature range from -40 °C to 35 °C. The temperature range investigated covers the soft segment glass transition of the polyurethane elastomer, which is about -20 °C. In the transition process, the dielectric loss of the polyurethane films with conductive polymer electrodes does not show any significant difference to that of polyurethane films with gold electrodes. This indicates that the conductive polymer electrodes function appropriately and that the direct deposition process did not change the dielectric properties of the solution-cast polyurethane films. However, when the temperature is higher than 35 °C, the dielectric loss of the polyurethane films with conductive polymer electrodes starts to increase and becomes higher than that of the films with gold electrodes. The increase in the dielectric loss might be a consequence of dehydration phenomena in the conductive polypyrrole, which has been suggested by several researchers and should occur in the temperature range from 60 to 100°C. See, for example, Ennis et al, Synth. Met, 59:387 (1993); Biswas et al, J Appl. Polym. Sci, 51, 1575 (1994); Biswas et al, J Appl. Polym. Sci., 60:143 (1996); Truong et al, Polymer, 36:1993 (1995).

Figure 3 compares the electric field induced strain coefficient (R) of the polyurethane films with conductive polymer electrodes and with gold electrodes. It can be observed that (i) the strain coefficient (R) for both polymer-electroded and gold- electroded films, increases when the sample thickness is decreased from 0.2 mm to 0.1 mm, and (ii) the strain coefficient (R) for both polymer-electroded and gold-electroded films shows frequency dependence, increasing with decrease in the measurement frequency; and (iii) the polymer-electroded films show higher R values than the gold- electroded films at frequencies higher than 10 Hz while the gold-electroded films show a more rapid increase in R than the polymer-electroded films with decrease of frequency. The strain coefficient (R) of the gold-electroded films becomes higher than that of the polymer-electroded films when the frequency is lower than 10 Hz. As reported by Su et al, Appl. Phys. Lett. 71 :386 (1997), for gold- electroded films, the higher strain coefficient (R) in 0.1 mm films as compared to that in 0.2 mm films and the rapid increase in the coefficient with decrease of frequency, show the existence of interfacial charge and space charge distribution effects. For the polymer-electroded films (Figure 3), charge effects are still significant even though not as strong as those in the gold-electroded films, and the increase of the strain coefficient with decrease in frequency is not as rapid as that in the gold-electroded films.

Without intending to be bound by any particular theory of operation, the higher strain coefficient in the polymer-electroded films in the higher frequency region might be caused by the reduced clamping effect of the polymer electrode as compared to the metal electrode, as described above. The critical thickness is the thickness at which neutralization and/or homogenization of these space charges might occur. The neutralization and/or homogenization will result in a weakening of the non-uniformity of the modified internal field. As a consequence, the enhanced electric field induced strain responses, which depend on a non-uniform field profile, will start to decrease as observed in Figures 4A-B.

Although the invention has been set forth in considerable detail, one skilled in the art will appreciate that numerous changes and modifications can be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

CLAIMS:

1. An electrostrictive system comprising a first layer of conductive polymer film, a layer of thermoplastic polymer elastomer film, and a second layer of conductive polymer film, wherein said elastomer film is located between said first and second layers of conductive polymer film.

2. The system according to claim 1, wherein said elastomer film is selected from the group consisting of polyurethane, poly(vinylidene fluoride), poly(vinylidene fluoride-trifluoroethylene) copolymers, and odd-numbered Nylons.

3. The system according to claim 2, wherein said elastomer film is polyurethane.

4. The system according to claim 2, wherein the thickness of said elastomer film is from about 50 ╬╝m to about 200 ╬╝m.

5. The system according to claim 1 , wherein said first and second layers of conductive polymer film are independently selected from the group consisting of doped polypyrrole wherein the pyrrole units are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C,-C₈ alkyl, C_rC₈ alkenyl, and C,-C₈ alkynyl, wherein said alkyl, alkenyl, and alkynyl substituents are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl and sulfonyl, doped polyaniline wherein the aniline units are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C,-C₈ alkyl, C,-C₈ alkenyl, and C,-C₈ alkynyl, wherein said alkyl, alkenyl, and alkynyl groups are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, and sulfonyl, and doped polythiophene wherein the thiophene units are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C,-C₈ alkyl, C,-C₈ alkenyl, C_rC₈ alkynyl, wherein said alkyl, alkenyl, and alkynyl substituents are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, and sulfonyl, and - O -(CH₂)_n-O- wherein n is 2 or 3 and the thiophene ring is simultaneously substituted at the 3 and 4 positions.

6. The system according to claim 5, wherein the dopant is selected from at least one of Br, Cl^", F\ ClO₄\ PF₆\ AsF₄\ AsF₆ ^", SO₃CF₃ ^", BF₄ ^", BC1₄ ^", VO₃ ^", PF₆\ POF₄\ CN^", SiF₆\ CH₃CO₂ ^" (acetate), C₆H₅CO₂ ^" (benzoate), CH₃C₆H₄SO₃ ^" (tosylate), SO₄ ^", benezenesulfonate, naphthalenesulfonate, dodecyl sulfonate, dodecylbenzenesulfonate, jo-toluenesulfonate, 2-acrylamide-2-methyl- 1 - propanesulfonate, methanesulfonate, anthraquinone-2-sulfonate, anthraquinone-1- sulfonate, anthraquinone-2,6-disulfonate, />-hydroxybenzenesulfonate, p- dodecylbenzene sulfonate, 5-n-butylnaphtahlenesulfonate, 5-sulfo-isophthalate, 8- hydroxy-7-iodo-5-quinonesulfonate, camphorsulfonate, 4,5-dihydroxynaphthalene-2, 7- disulfonate, 5 -amino-2 -naphthalenesulfonate, anthraquione-1, 5-disulfonate, polystyrenesulfonate, or polyvinylsulfonate.

7. The system according to claim 5, wherein said first and second layers of conductive polymer are doped polypyrrole.

8. The system according to claim 7, wherein said dopant is anthraquinone-2-sulfonate.

9. The system according to claim 5, wherein each pyrrole repeat unit has an oxidation state from about +0.28 to +0.32.

10. The system according to claim 5, wherein each said first and second layer of conductive polymer is doped polyaniline.

11. The system according to claim 10, wherein each aniline repeat unit is in the emeraldine oxidation state.

12. The system according to claim 5, wherein each said first and second layer of conductive polymer is doped polythiophene.

13. The system according to claim 12, wherein each thiophene repeat unit has an oxidation state from about +0.25 to +0.5.

14. The system according to claim 5, wherein said first and second layer of conductive polymer film thickness is from about 200 A to about 1000 A.

15. The system according to claim 14, wherein said conductive polymer film thickness is about 300 A.

16. A method of producing an electrostrictive system comprising the steps of :

(a) providing a thermoplastic polymer elastomer film having opposing surfaces;

(b) depositing a first layer of a conductive polymer film onto one surface of said elastomer film; and (c) depositing a second layer of a conductive polymer film onto the opposing surface of said thermoplastic polymer film.

17. The method according to claim 16, wherein said first and second layers of conductive polymer films are deposited by immersing said elastomer film into a polymerizing solution comprising monomer units of said conductive polymer, at least one dopant, and an oxidant for a time and under conditions sufficient to form said conductive polymer film.

18. The method of claim 16, wherein said thermoplastic polymer elastomer film is selected from the group consisting of polyurethane, poly(vinylidene flouride), poly(vinylidene fluoride-trifluoroethylene) copolymers, and odd-numbered Nylons.

19. The method of claim 16, wherein said first and second layers of conductive polymer film are selected from at least one of doped polypyrrole wherein the pyrrole units are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C_rC₈ alkyl, C_rC_g alkenyl, and C,-C₈ alkynyl, wherein said alkyl, alkenyl, and alkynyl groups are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, and sulfonyl, doped polyaniline optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C,-C₈ alkyl, C_rC₈ alkenyl, and C,-C₈ alkynyl, wherein said alkyl, alkenyl, and alkynyl groups are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, and sulfonyl, and doped polythiophene optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, sulfonyl, C,-C₈ alkyl, C_rC₈ alkenyl, and C_rC₈ alkynyl, wherein said alkyl, alkenyl, and alkynyl groups are optionally substituted with at least one of hydroxyl, alkoxyl, halo, amino, cyano, carbonyl, carboxyl, and sulfonyl, and - O -(CH₂)_n-O- wherein n is 2 or 3 and the thiophene ring is simultaneously substituted at the 3 and 4 positions, wherein the dopant is selected from at least one of Br, Cl^", F-, ClO₄ ^", PF₆ ^", AsF₄ ^", AsF₆ ^", SO₃CF₃", BF₄ ^", BC1₄ ^", VO₃\ PF₆ ^", POF₄ ^", CN^", SiF₆\ CH₃CO₂ ^" (acetate), C₆H₅CO₂- (benzoate), CH₃C₆H₄SO₃ ^" (tosylate), SO₄ ^", benezenesulfonate, naphthalenesulfonate, dodecyl sulfonate, dodecylbenzenesulfonate, ,9-toluenesulfonate, 2-acrylamide-2-methyl- 1 -propanesulfonate, methanesulfonate, anthraquinone-2-sulfonate, anthraquinone- 1 -sulfonate, anthraquinone-2,6-disulfonate, >-hydroxybenzenesulfonate, j9-dodecylbenzene sulfonate, 5-n- butylnaphtahlenesulfonate, 5-sulfo-isophthalate, 8-hydroxy-7-iodo-5-quinonesulfonate, camphorsulfonate, 4,5-dihydroxynaphthalene-2, 7-disulfonate, 5-amino-2- naphthalenesulfonate, anthraquione-1, 5-disulfonate, polystyrenesulfonate, or poly vinylsulfonate .

20. The method of claim 16, wherein said first and second layers of conductive polymer film are doped polypyrrole.

21. The method of claim 16, wherein each said first and second layer of conductive polymer is doped polyaniline.

22. The method of claim 16, wherein each said first and second layer of conductive polymer is doped polythiophene.

23. The method of claim 16, wherein said first and second layers of conductive polymer film are deposited onto said thermoplastic elastomer polymer film to a thickness of from about 200 ╬¢ to about 1000 A, wherein steps (b) and (c) are repeated until the desired thickness is obtained.

24. The method of claim 23, wherein said first and second layers of conductive polymer film are formed to a thickness of about 300 A.