CA1277989C

CA1277989C - Self-doped polymers

Info

Publication number: CA1277989C
Application number: CA000520452A
Authority: CA
Inventors: Fred Wudl; Alan Heeger
Original assignee: University of California San Diego UCSD
Current assignee: University of California San Diego UCSD
Priority date: 1986-03-24
Filing date: 1986-10-14
Publication date: 1990-12-18
Anticipated expiration: 2007-12-18
Also published as: JPH09120709A; CN86107279A; JPS6339916A; KR960009685B1; KR100206730B1; DE3688615T2; JP2858648B2; WO1987005914A1; KR960012361B1; CN1019809B; EP0262147A4; EP0262147A1; DE3688615D1; EP0262147B1; JP2668060B2; CN1059914A; ATE90948T1; KR880701254A

Abstract

SELF-DOPED POLYMERS
Abstract Self-doped conducting polymers are provided which have along their backbone a pi-electron conjugated system comprising a plurality of monomer units, between about 0.01 and 100 mole % of the units having covalently linked thereto at least one Bronsted acid group. Examples of such polymers are represented by the following structural Formulas:

Formula I

Formula II

wherein Ht is a heterogroup, Y1, Y2, Y3 and Y4 are independently selected from the group consisting of hydrogen and -R-X-M, R is a linear or branched alkyl, ether, ester or amide moiety having between 1 and about 10 carbon atoms, x is a Bronsted acid anion, and M is an atom which when oxidized yields a positive monovalent counterion. The invention also encompassses the aforementioned monomers themselves as well as the conducting, zwitterionic form of the polymers, i.e., wherein the -R-X-M moieties have been ionized to yield -R-X
species and in which a positive charge is distributed along the polymer backbone. Also included within the scope of the invention are electrodes comprising one or more of the novel polymers.

Description

1'~779~39 SELF-DOPED POLYMERS

Field of the Invention This invention relates generally to the field of conducting polymers. More particularly the invention relates to self-doped conjugated polymers in which sronsted acid groups are covalently bound to the backbone of the polymer.

Background The requirements for conductive polymers used in the electronic and other industries are becoming more and more stringent. There is also an increasing need for materials which permit reduction in the size and weight of electronic parts and which themselves exhibit long-term stability and superior performance.
In order to satisfy these demands, active efforts have been made in recent years to develop new conductive macromolecular or polymeric materials. A number of proposals have also been made regarding the potential uses of such new compounds. For example, P.J. Nigrey et al. in Chem. Comm.
pp. 591 et seq. (1979) have disclosed the use of polyacetylenes as secondary battery electrodes. Similarly, A. Heeger in J. Electro Chem. Soc., Volume 128, No.2, p. 1651 et sea (1981) and others have also disclosed the use of polyacetylenes, Schiff base-containing quinazone polymers, polarylene quinones, poly-p-phenylenes, poly-2, 5-thienylenes and other polymeric materials as electrode materials for 1~:77989 secondary batteries.
The use of polymeric materials in electrochromic applications has also been suggested, in, e.g., A.F. Diaz et al., J. Electroanal. Chem. 111: 111 eq seq. (1980), Yoneyama et al., J. Electroanal. Chem. 161, p. 419 (1984) (polyaniline), A.F. Diaz et al., J. Electroanal. Chem. 149:
101 (1~83) (polypyrrole), M.A. Druy et al., Journal de Physiaue 44: C3-595 (June 1983), and Kaneto et al., Japan Journal of Applied Physics 22(7): L412 (1983) (polythiophene).
These highly conductive polymers known in the art are typically rendered conductive through the proceRs of doping with acceptors or donors. In acceptor doping, the backbone of the acceptor-doped polymer is oxidized, thereby introducing positive charges into the polymer chain.
Similarly, in donor doping, the polymer is reduced, so that negative charges are introduced into the polymer chain. It is these mobile positive or negative charges which are externally introduced into the polymer chains that are responsible for the electrical conductivity of the doped polymers. In addition, such "p-type" (oxidation) or "n-type"
~reduction) doping is responsible for substantially all the changes in electronic structure which occur after doping, including, for example, changes in the optical and infrared absorption spectra.
Thus, in all previous methods of doping the ;. . , . ~................... .

~.~77989 counterions are derived from an external acceptor or donor functionality. During electrochemical cycling between neutral and ionic state6, then, the counterions must migrate in and out of the bulk of the polymer.
This solid state diffu6ion of extecnally introduced counterions is often the rate-limiting step in the cycling process. It i6 thu6 desirable to overcome this limitation and theceby increase the response time in electrochemical or electrochromic doping and undoping operations. It has been found that the response time can be shortened if the period required for migration of counterions can be curtailed. The present invention is e~edicated upon this di6covery.

SUmmarY of the Tnvention The peesent invention provide6 conducting polymer~ that can be rapidly doped and undoped, and wh~ch are capable of maintaining a 6table, doped state eO~ long periods of time relative to conducting polymer6 of the prior art. The supeior propertie6 of the polymer~ of the pre~ent invention re6ult from the discovery that conductinq polmers can be made in a "~elf-doped" form; i.e., the counterion that povides conductivity can be covalently linked to the polymer itself. Tn contcast to the polymers of the erior art, therefore, the need for extecnally introduced counterions is obviated, and the rate-limiting diffusion step alluded to above i8 eliminated as well.
The polymecs of the invention can di6play conductivities of on the o~der of at least about 1 ~/cm. The self-doped polymers may be u6ed as electrodes in electcochemical cells, as conductive layers in electrochromic displays, field effective transistors, Schottky diodes and the like, or in any number of 7'7989 applications where a highly conductive eolymer which exhibits rapid doping kinetic6 is desirable.
In its broadest aspect, the pre6ent invention is directed to a conducting self-doped polymec having along its backbone a ~-electron con~ugated system which comprises a plurality of ~ono~er units, between about 0.01 and 100 mole % of said units having covalently linked theceto at least one Bron6ted acid group. The present invention al60 encompas~ses the zwitterionic form of 6uch polymer6. Polymer5s which may focm the backbone of the compounds of the pre6ent invention include, for example, polypyrrole6, polythiophenes, polyi~othianaphthene6, polyanilines, poly-p-phenylene6 and copolymer6 thereof.
In a preferced embodiment, self-doped polymer6 de~cribed above have a recurring 6tructure selected ~ro~
the following structures (I) or (II):

yl RX-M

( I ) ~H~

--~Y3 Yf~

~.r 5,~, ~'~77989 wherein, in Formula I: ~t i6 a heterogcoup: Yl i6 selected from the group con6i~ting of hyd~ogen and -R-X-M; M is an atom or groue which when oxidized yields a eo6itive ~onovalent counterion; X i6 a Bronsted acid anion: and R i6 a linear or branched alkyl, ether. e~ter or amide ~oiety having between 1 and about 10 carbon ato~. In Focmula II, Y2, Y3 and Y4 are independently selected fro~ the group consisting of hydrogen and -a-X-M, and R, X and M are a~ given for Focmula I.
In yet another preferred e~bodiment oe the invention, a conductive polymer is provided containing a tecurcing zwitterionic structure accocding to (Ia) oc (lIa):

R-X~

(Ia) RX~3 RX ~) (lIa) whecein Ht, a and X ace as defined above.

.
'.

. :. .

~77989 The invention is al60 directea to ~onomer6 u6eful in ~aking the above 6elf-doped polymer~, method6 of synt~esizing the poly~ers. and device6 employing the polymer6 .
s ~rief De~criDtion of the Drawina6 FIG. 1 i6 an infrared 6Pectrum of poly(methyl thiophene-3-(2-ethanesulfonate).
FlG. 2 i6 an infrared 6pectrum of poly(thiophene-3-(2-ethane~ulfonic acid sodium salt).
FIG. 3 is an infrared ~pectrum of poly (methylthiophene-3-(4-butane~ulfonate).
FIG. 4 is an infrared spectrum of poly (thiophene-3-(2-butanesulfonic acid ~odium ~alt).
FIG. S depicts a 6erie6 of vi6-near ir 6pectra of poly~thiophene-3-~2-ethane6ulfonic acid) 60dium salt):
FIG. 6 depicts a 6erie6 ov vi6-near ir 6pectra of poly(thiophene-3-(4-butane6ulfonic acid) 60dium 6alt);
FIG. 7 depict6 a 6erie6 ov vi6-near ir 6pectra of pOly(methyl thiophene-3-(4-butanesulfonate).
FIG. S illu6t~ate6 the reBult6 of cyclic voltamaetry caccied out on films of poly(thiophene-3-sulfonic acid): and FIG. 9 depict6 a series of vis-near ir ~pectra of poly(thiophene-3-sulfonic acid).

Detailed DoscciDtion The ter~6 ~conducting" or ~conauctive~ indicate the ability to transmit electric charge by the pa66age of ionized ato~s or electrons. ~Conaucting~ or ~conductive~ co~pouna6 include compound6 which embody or incorporate ~obile ions or electrons as well a6 co~pound6 which ~ay be oxidizea 60 as to e~body or incocpocate ~obile ions or electrons.
h~

~:77989 The term ~elf-doping~ mean~ that a material may be rendered conducting or conductive without external introduction of ion~ by conventional doeing technique~. In the ~elf-doping polymer~ di6clo~ed herein, potential counterionfi are covalently bound to the polymer backbone.
The term ~Bron~ted acid~ u~ed to refer to a chemical specie~ which can act as a source of one or more proton6, i.e. as a proton-donor. See, e.a., the McGcaw-Hill Dictionary of Scientific and Technical Terms (3td Ed. 19~4) at page 220. Examples of Bronsted acid~
thus include carboxylic, ~ulfonic and phosphoric acids.
The term "Bronsted acid group" as u6ed herein means Bconsted acids as defined above, anions of Beonsted acids (i.e. where the protons have been removed), and salt~ of ~ron~ted acids, in which a Bronsted acid anion i8 as~ociated with a monovalent cationic counterion.
"Monomer units~' a~ used herein refer to the cecurring ~tructural units of a polymer. The individual monomer units of a pacticular polymer may be identical, as in a homopolymer, or diffeeent, a6 in a eopolymer.
The polymers of the present invention, which may be copolyme~s oc homopolymer~, have a backbone steuctuce that p~ovides a ~-electron con3ugated ~y~tem. Example6 of such polymer backbones include, but ace not limited to, polypyrtoles, eolythiophenes, polyisothianaphthenes, polyanilines, poly-p-phenylene~
and copolymers thereof. The recurring structure desccibed above may con~titute anywhere from about 0.01 to about 100 mole % monomers substituted with one or more "-a-X-M" functionalities. In application6 requiring high conductivity, usually at least about 10 mole % of the monomer units are ~ubstituted, typically about 50 to loo mole %. In 6emiconductor ap~lication6, it i6 u6ually le66 than about 10 mole ~ of the monomeL
unit6 that are 6ubstituted, æometime6 as little a6 about 0.1 or about 0.01 mole %.
Polyheterocycle monomer unit~ repre6ented by Formulae I and Ia include monomer units which are eithec mono-~ubstituted oc di-substituted with the -R-X-M
fur.ctionality. Similacly, the polyaniline monomer units represented by Focmulae II and IIa include monomer units which are substituted with 1, 2, 3 oc 4 "-R-X-M"
substitutents. Coeolymers encompassing these different types of 6ubstituted monomer unit6 are envi6ioned by the eresent invention a6 well. In both the homopolymers and copolymers of the present invention, between about 0.01%
and 100 mole % of the polymer should be provided with Bronsted acid geoups.
In a preferced embodiment, the present invention encompasses electcically neutcal eolymers given by Formula I or II above. In ocder to cender the Z polymecs conductive, they must be oxidized 80 as to remove the M moiety and yield a polymer containing a recuccing zwittecionic structure according to Ia or IIa. In the pceferred embodiment, for example, Ht may be selected from the 910Up consisting of NH, S, O, Se and Te: M may be H, Na, Li or ~: X may be COz, S03 oc HP03: and R is a straight chain alkyl or ether group (i.e., -(CHz)x- or -(CHz)yO(CHz)z~, where x and ~y~z) are from L to about 10). In a particulacly prefecced embodiment, Ht is NH or S: M is H, Li or Na: X i8 C02 or S03: R is a linear alkyl having fcom Z to about 4 carbon atoms: and the substituted monomec~ of the eolymers are either mono- or di-substituted with -R-X-M groues.

1'~77~8~

g In order to "undoee" the zwitterionic for~ of the polyme~s, an electric charge may be sueplied in the direction contrary to that used in doping (alte~natively, a ntild eeducing agent may be used a~
di6cu6sed below). The M moiety is caused to migrate into the eolymer and neutralize the X counterion.
The undoping proce6s is thus as rapid as the doping proce66 .
Scheme I and Scheme II represent the oxidation and ceduction of the above polymers (the mono-substituted embodiment is illustrated). i.e. the transition between the electrically neutral and conductive zwitterionic form6:

Y~RX-M Yl X~
/r\l~ -M+(Oxidation) /~_~
Scheme I_ ~ ~ ~ ~ ~ _ Hl +M~ (Reduclion) Ht Y2 ~X-M Y2 ~
\ -M~ (Oxidation) ~ \
~ ~ q r ,~NH' ... ,~ '' .. ~. ~(~)~--NH' , 25 Scheme II ~ +Mt(Reduclion) \~J

Where X is C02, the above electrochemical conver6ion i8 strongly pH-dependent in the pH range of 1-6 (the PKa for X.C02 and M.H in Formula I is about 5).
Where X is S03, on the other hand, the above electrochemical reaction is pH-independent over the much ~ ~77989 la~ge~ pH ~ange of about 1-14 ~the PKa fo~ X=S03 and M=H in Formula II i~ about 1). The ~ulfonic acid de~ivative i6 thu~ cha~ged at virtually any pH, while the cacboxylic acid derivative is charged at only lowe~
pH. By va~ying the pH of the polymer solution, then, it is easier to cont~ol the conductivity of the ca~boxylic acid derivative~ than that of the cor~esponding ~ulfonic acid derivative6. The pa~ticular Bron~ted acid moiety ~elected will thus depend on the particula~ application.
The6e self-doped polymers have conductivitie~
of at least about 1 S/cm (see Example 14) and typically have chain length~ of about seve~al hund~ed monomer units. Tyeically, chain lengths ~ange from about 100 to about 500 monomer units: higher molecula~ weights are L5 pceferred.
In the practice of the present invention, a Bronsted acid groue is introduced into a polymer to make it ~elf-doping. The Bronsted acid may be introduced into a monomec, followed by eolymerization or copolyme~ization. One may also prepare a polymer~oc copolymer of the unsubstituted monome~6 of Fo~mulae I or II and then intcoduce the B~onsted acid into the polymec backbone.
Covalently linking a Bronsted acid to a monomer oc eolymer is within the skill of the act. See, e.a., J.Am.Chem. Soc. 70:1556 (1948). By way of illust~ation, an alkyl gcoup on a monomec or polymer backbone can be concatenated to an alkyl halide using N-bromo ~uccinamide (NBS) as shown in Scheme III:

_ t ,~

~"~77989 CH3 CH2Br Scheme III

The halide can then be treated with sodium cyanide/sodium hydroxide or sodium sulfite followed by hydrolysis to give a carboxylic or sulfonic Bronsted acid, ~espectively, as ~hown in Scheme IV:
/CH.COOH
CH2Br ~ NaOH

Scheme IV

~SOJ

Another example 8howing the addition of a B~on6ted acid with an ether lin~ing g~oup is shown in Scheme V:

,~

1.'~7~989 CH2Br ~3 + !~laOCH2CH2C--OCH,CH3 Scheme v CH20CH2CH2C= OCH2CH3 l H20 Ht Syntheses of variou~ monomers useful in the practice of the present invention are set forth in Examples 1 through 12, below.
The polymers of the present invention may be ~ynthesized by the electrochemical methods set forth in, e.g., S. Hotta et al., SYnth. Metals 9:381 (1984), or by chemical couplinq methods such as those described in Wudl et al., J. ora. Chem. 49:3382 (1984), Wudl et al., Mol. Crvst. Liq. CeY~t. L18:199 (1985) and M. ~obayashi et al., SYnth. Metals. 9:77 (1984).
When synthesized by electrochemical methods (i.e., anodically), the polymeric zwitterions are produced directly. With the chemical coupling methods, the neutral polymers result. The preferred synthetic method is electrochemical, and is exemplified below by the production of a substituted polyheterocyclic species.

~ ~7798~3 -~3-A solution containi~g the monomer III

Y RX-M
(III) with Ht, Yi, R, X and M as given above, is provided in a ~uitable solvent such as acetonitrile (parcicularly suitable for the sulfonic acid derivative, i.e. where X~S03) along with an electrolyte such as tetrabutylammonium perchlorate or tetrabutylammonium fluoroborate. A working electrode of platinum, nickel, indium tin oxide (IT0)-coated glass or other suitable material is provided, as is a counterelectrode (cathode) oS platinum or aluminum, preferably platinum. ~ current of between about 0.5 and 5 mA/cm is applied across the electrodes, and deeending on the extent of polymerization desired (or the thickness o~ the polymeric film on a substrate), the electropolymerization reaction is carried out for between a Sew minutes and a Sew hours. The temperature Z5 of the polymerization reaction can range Srom about -30C to about 25C, but is preSerably between about 5C
and about 25C.
Reduction of the zwitterionic polymer so pcoduced to the n~utral, undoped form may be effected by electrochemical reduction or by treatment with any mild reducing agent, such as methanol or sodium iodide in acetone. This erocess should be allowed to proceed for at least several hours in order to ensure completion of the reaction.

~, The sulfonic acid monomer (X-SO3) is polymerized a~ the methyl ester (see Examples 14 and 15), while the carboxylic acid derivative (x8co2) may be ~re~ared in its acid form. ~fter polymeri2ation of the sulfonic acid derivative. the methyl group is removed in the treatment with sodium iodide or the like.
Tbe polyanilines cepre6ented by Formulae II and IIa may be synthesized electrochemically as above or they may be prepared by the reaction of a phenylenediamine with a suitably substituted cyclohexaneaione. Scheme VI, below. illustrates this latter synthesis: RCOOC2H5 Q)--~ polymenze H2N~NH2 + ~--RC00C2Hs Scheme VI

k~ ~

R, X and M are as defined above.
Copolymerization of different types of monome~s represented in Pormulae I or II may be effected according to the same procedure~ outlined above. In a prefecred embodiment. the majority of monomers are at least mono-substituted with an -R-%-M group as de6cribed.
Compo6ite6 of the polymecs Oe Formulae I and II
may be pcepared in conjunction with water-soluble poly~ers such as polyvinyl alcohol (6ee Example 171 and the polysaccharide6. 8ecause the eolymers of the present invention may be fairly b~ittle, preparation of compo~ite~ using additional polymeric material6 provides polymers which are more flexible and less brittle.

Film~ may be ca~t f~om aqueou~ ~olutions of ~olyme~
given by Formulae I o~ II al~o containing a predetermined amount of one o~ more additional water-601uble polymers. Since the key p~ocedu~al criterion in thi6 step i6 di6601ving two or more polymer6 in water, the only practical limitation on the additional polymer6 i6 that they be water-soluble.
The polymer6 of the pre6ent invention offer a specific advantage over conventional conducting polymer6 for use as electrode6 in electrochemical cell6. Becau6e the counterions are covalently bound to the polymer, the cell caeacity is not limited by electrolyte concentration and solubility. This means that in optimized cell~, the total amount of electrolyte and solvent can be reduced considecably, thu6 enhancing the energy density of the re6ulting battery. The facile kinetics of ion tcan6port provided by the novel ~elf-doping mechanism leads to rapid charge and di~cha~ge as well as to faster electrochromic switching. Electrode6 fabricated u6ing the polymer~ of the invention may be fabcicated entirely from these polymec6 or from conventional 6ub6trates coated with these polymers. Conventional substrates may include, for example, indium tin oxide coated glass, elatinum, nickel, palladium or any other suitable anode mateeial~. When used as an electrode, the internal self-doping of the polymer effects the transition repce~ented by Scheme I.
i The self-doeed conducting polymees of the invention also offer specific advantages over conventional conducting polymers for use in a variety of device applications where long term performance ~equi~es that the dopant ions not be continuously mobile.
Examples of ~uch uses include fabrication of Schottky . .
diodes, field effective tran6isto~s, etc. Because the doeant ion i6 covalently bound to the polymer chain in self-do~ed polyme~6, the problem of diffu6ion of the ion (e.g., in the vicinity of a junction or interface~ is solved.

ExamPle6 It i6 to be understood that while the invention has been desc~ibed in con3unction with the ereferred 6pecific embodiment thereof, that the foLegoing de6cription as well as the exameles whic~ follow are intended to illustrate and not limit the scoee of the claimed invention. Othe~ aspects, advantages and moaifications within the scope of the invention will be apparent to those skilled in the a~t to which the invention ee~tains.

Example 1

2-(3-ThienYl~-Ethvl Methane~ulfonate To a solution of 5.o g (7.8xlO 3 mol) of Z-(3-thienyl)-ethanol (Ald~ich Chemical) in 10 ml of d~y, f~eshly distilled py~idine was added 3.62 ml (1.2 equiv.) of methane~ulfonyl chloride in 20 ml of ey~idine at 5-10C. The addition was ca~ied out gradually, over a pe~iod of about 15-20 min. The ceaction mixtu~e was sti~ed overnight at ~oom tempe~ature and was quenched by pou~ing into a sepa~ato~y funnel containing water and ethe~. The layec~ we~e sepa~ated and the aqueous laye~
wa~ extractea th~ee times with ether. The combined organic extracts we~e extcacted once with 10%
hydrochloric acid, followed by wate~ and d~ying ove~
Na2S04. Evapo~ation of the 601vent affoLded 5.3g of a light bcovn oil l6$~ yield), and elc (CHCl3) 6nowed . ':

7~989 a single spot. Chromatographic purification on ~ilica gel af~orded a light yellow oil. Nm~ (CDC13. ~ rel TMS) 2.98, 3H; 3.1t, 2H: 4.4t, 2H: 7.0-7.4m. 3H. Ir (neat, v, cm l) 3100w, 2s30w, 29202, 141sw, 1355~, 13358, 1245w, 1173s, 1osow, lossw. 9708, 9556, 903m, 850m, 825w, 7956, 775~, 740w. MS, 206Ø

Example z 2-(3-Thienvl)-EthYl lodide 10The above methanesulfonate (5.36, 2.6x1o-2 mol) wa~ added to a ~olution of 7.7g (2 equiv) of ~aI in 30 ml of acetone and allowed to ceact at room tempecature for 24 hc. The CH3S03Na which had precipitated was separated by filtration. The filtrate was poured into wate~, e~tracted with chloroform, and the o~ganic laye~ was d~ied ove~ MgS04. Evaporation oS the solvent affocded a light brown oil which upon chromatogcaphic puciSication gave 5.05g of a light yellow oil (82.5~). Nm~ (CDC13, ~ rel to TMS):

3.2m, 4H; 7.0-7.4m, 3H. Ir (K~ , cm 1): 3100m, 2960~, 29208, 2850w, 1760w, 1565w, 1535w, 1450m, 14288, 1415~, 1390w, 1328w, 1305w, 12558, 1222m, 11708, 1152m, llOOw, 1080m, 1020w, 940m, 900w, 857s, 8408, 810w, 7706, 6958, 633m. MS 238.
ExamDle 3 Sodium-2-(3-Thien~l~-Ethanesulfonate To a 10 ml aqueou6 solution of 5.347g (4.2xlOmol) of Na2S03 was added 5.05g (0.5 equiv) of the above iodide and the reaction mixture wa~
heated to 70C for 45 hr. The resulting mixtu~e was evaporated to d~yness Sollowed by washing with chloroform to ~emove the un~eacted iodide (0.45 g) and acetone to ~emove the sodium iodide. The ~emaining 7~ ~9 ..
601id wa~ a mixtuce of the de6iced sodium ~alt contaminated with exces~ 60dium sulfite and wa6 used in 6ub6equent 6tep6 without further eurification. Nmr (D2O, ~ rel ~MS proeane6ulfonate): 3.1~, 4H:
7.0-7.4m, 3H . I ~ (KBr, ~, cm 1, Na2S03 peak6 ~ubt~acted) 1272m, 1242~, 12106, 1177s, 1120m, 10566, 760m, 678w.

Example 4 2-(3-ThienYl~-Ethane~ulfonYl Chloride To a stirred ~u~pen~ion of 2 g of the above mixture of salts prepared in Example 3 was added dcopwi~e 2 ml of distilled thionyl chloride. The mi%tuce wa~ allowed to stir foc 30 min. The white ~olid resulting ~rom ice-water quench wa~ separated by filtration and cecrystallized f~om chlocoform-hexane to afford 800 mg of white cry6tals, mp 57-58C. Nmr (CDC13, ~ cel TM8) 3.4m, 2H: 3.9m, 2H: 7.0-7.4m, 3H. Ir (KBr, v, cm 1) 3100w, 2980w, 2960w, 2930w, 1455w, 1412w, 135B8, 127Bw, 1260w, 1225w, 11658, 1075w, 935w, B65m, B30m, 7908, 770w, 750m, 67B6, 625m. El.
Anal. Calcd. for C6H7ClO2S2: C, 34.20; H, 3.35:
Cl, 16.83; S, 30.43. Found: C, 34.38: H, 3.32: Cl, 16.69; S, 30.24.
ExamPle 5 MethYl 2-(3-ThienYl)-Ethanesulfonate To a sticced ~olution of 105 mg (5xlO mol) of the above acid chloeide (pcepared in Example 4) in l.S ml of ereshly distilled (from molecular sieve6) methanol wa6 added, at coom tempecature, 1.74 ml (2 equiv) of N,N-dii60pcopylethylamine. The reaction mixture wa6 6tirred for 12 hr and then tran6ferced to a 6eparatory funnel containing dilute, aqueou6 HCl and wa6 :, ;

7~798~

extracted with chlorofocm thrice. After the combined organic layers were dried with Na2S04, the 601vent was evaporated to affoed a light brown oil which wa~
eueified by chromatography on 6ilica gel with chloroform S as eluent. The resulting coloeles6 601id, obtained in 90% yield had an me of 27-28.5OC. Ir (neat film, v, cm 1) 3100w, 2960w, 2930w, 1450m, 1415w, 1355s, L250w, 11656, 9858, 840w, 820w, 780m, 630w, 615w. Uv-vis t~aX. MeOH, nm(~)] 234 ~6X103). Nmr (CDC13, ~ eel TMS) 7.42-7.22q, lH: 7.18-6.80m, 2H; 3.85s, 3H:
3.6-2.9m, 4H. El. Anal. Calcd. for C7H10O3S2:
C, 40.76; H, 4.89; S, 31.08. Found: C, 40.90; H, 4.84;
S, 30.92.

Exam~le 6 EthYl-2-Carboxvethvl-4-(3-Thienvl~-Butanoate To a sticred solution of 11.2 g (69.94 mmol) of diethyl malonate in 60 ml of fre6hly distilled DMF, was added 2.85 g (69.94 mmol) of a 60% oil di6per6ion of NaH. Aftee 30 min 6tirring, 15.86 g (66.61 mmol) of 2-(3-thienyl)-ethyl iodide (prepared a6 de6~ribed above) in 20 ml o~ DM~ wa6 added dropwise over 10 min. The ceaction mixture was stiered at eoom temperatuee foe one hr and then heated to 140 for foue hr. Upon cooling, the reaction was poured into ice-dil. HCl and extracted ~ix time~ with ether. The combined organic layers weee wa~hed with watec, dried with Na2S04 and evapoeated to afford a brown oil. A~ter chromatography on silica gel (50% hexane in chloro~orm), a colorless oil wa~
obtained in 98% yield. El. Anal. Calcd. for C13H1804S: C, 57.76; H, 6.71: S, 11.86. Found:
C, 57.65; H, 6.76: S, 1~.77. Nmr (CDC13, ~ rel TMS) 7.40-7.20t, lH; 7.10-6.86d, 2H: 4.18q, 4H: 3.33t, lH:

7~798 2.97-1.97m, 4H: 1.23t, 6H. Ir (neat film, v, cm~L) 2980w, 17306, 1450w, 1370w, 775w.

Example 7 2-Ca~boxv-4-(3-ThienYl)-Butanoic Acid To a stirred ~olution of 1.4 g (24.96 mmol) of potas~ium hydroxide in 7.0 ml of 50% ethanol in water, wa~ added the above die~te~ (765 mg, 2.83 mmol) ~repared in Exam~le 6. The ~esulting reaction wa~ allowed to sti~ at room tempecature for two hr, followed by ove~night reflux. The resulting mixture wa6 poured into ice-10% HCl, followed by three ether extractions. The combined o~ganic layec was dired with Na2S04 and eva~orated to affocd a wh~te so}id in 90~ which wa~
~eccystallized feom chlorofocm-hexane to p~oduce colorle88 neeale8. Me, 118-119C: nm~ (DMS0/d6, ~ ~el TMS) 12.60bc 6, 2H: 7.53-6.80m, 3H: 3.20t, lH 2.60t, 2H; 1.99q, 2H. I~ (K8r, v, cm ) 2900w, 17108, 1410w, 1260w, 925w, 780s. El. Anal. Calcd. for C9H1004S: C, 56.45; H, S.92: S, 18.83. Found:
C, 56.39; H, 5.92; S, 18.67.

Exam~le 8

4-(3-Thienvl)-ButYl Methanesulfonate 4-(3-thienyl)-butanoic ac~d (CA 69:18565x, 72:121265k) was e~eea~ed by standa~d thecmal deca~boxylation of the carboxy acid e~epared in Example 7. This comeound was then ~educed to give 4-(3-thienyl)-butanol (CA 70:6B035~, 72: 121265k) also uB~ng 8tandard ~ethod6.
~o a 601ution of 1.05 9 (6.7xlO- mol) of 4-(3-thienyl)-butanol in 25 ml of dry, fre6hly di6tilled ; eycidine wa6 added 0.85 9 (1.1 equiv.) of methane-6ulfonyl chloLide at 25C. The addition wa6 .,~
,~

. ., .. :.

77 9~9 gradual and carcied out ovee a 6eveLal minute period.
The ceaction mixtuee wa6 ~ticred for 6 hr at room temperature and quenched by pou~ing into a se~artoey funnel containing water-HCl and ether. The layers were ~epaeated and the aqueou~ layer was extracted once with 10% hydeochlocic acid, followed by exteaction with water and d~ying with Na2SO4. Evapoeation of the 601vent afforded ~ sl g of a light beown oil (95% yield), tlc (CHC13) showed a single spot. El. Anal. Calcd. fo~
lo CgH1403S2: C, 46.13; H, 6.02; S, 27.36.
Found: C, 45.92; H, 5.94; S, 27.15. Nme (CDC13, rel TMS) 2.0-1.5 brs, 4H; 2.67 bet, 2H: 2.976, 3H:
4.22t, 2H; 7.07-6.80d, 2H; 7.37-7.13, lH.

Exam~le 9 4-(3-ThienYl ButYl Iodide) The above methane6ul~0nate (1.51 g, 6.4x~0 3 mol) pcepaeed in Example 8 wa~ added to a 601ution of 1.93 g (2 equiv.) of NaI in 14 ml of acetone and allowed to react at eoom tempeeatuce ovecnight. The eeaction mixtu~e wa~ then heated to reflux for 5 hc. The CH3S03Na which had precieitated wa~ ~epaeated by filteation. The filteate wa6 poueed into watee, extcacted with chloeofoem and the oeganic layee was dried with MgS04. Evapoeation of the solvent affoeded a light beown oil which upon cheomatogeaphic purification (silica gel, 60% hexane in chloeoform) gave 1.34 g of a colorles~ oil (78%). Nmr (CDC13, ~ eel to TMS) 1.53-2.20m, 4H; 2.64t, 2H; 3.17t, 2H;
6.83-7.10d, 2H; 7.13-7.37t, lH. Ir (KBe, v, cm 29606, 29056, 2840~, 1760w, 1565w, 1535w, 1450s, lq286, 14156, 11908, 7506, 695m, 633m. MS 266Ø El. Anal.
Calcd. for CBHl~IS: C, 36.10; H, 4.17; I, 47.68; S, 12.05. Found: C, 37.68; H, 4.35; I, 45.24; S. ~2.00 ~ 77989 ExamPle 10 Sodium-4-(3-ThienYl~-Butanesulfonate To a 2 ml aqueou~ 601ution of 1.271 g (~xlo-2 mol) of Na2S03 was added 1.34 g (0.5 equiv) of the above iodide eeepaced in Example 9. The eeaction mixture wa6 heated to reflux for 18 h~. The ~esulting mixtuce wa6 e~aeocated to dcyness, followed by wa6hi~g with cblo~oform to ~emove the unceacted iodide and with acetone to remove the sodium iodide. The remaining ~olid was a mixtu~e of the de6ieed sodium salt contaminated with excess sodium sulfite and wa6 used in subsequent stee6 without fucthec pucification. Nmr ~D20, ~ cel TMS peoeane-6ufonate) 1.53-1.97m, 4H:
2.47-3.13m, 4H: 6.97-7.20d, 2H; 7.30-7.50q, lH. Ic (KB~, v, cm , Na2S03 ~eak6 subtracted) 2905w, 1280m, 12108, 11808, 1242m, 12106, 11806, 1130~, 10606, 970~, 77008, 690w, 630s, 605s.

ExamPle 11 4-(3-ThienYl~-Butanesulfonvl Chlo~ide To a 6ticced 6u6pen6ion of 1.00 g of the above mixtuce of 6alts ~from Example 10) in 10 ml of fceshly di6tilled DMF was added dcopwi~e 1.43 g of distilled thionyl chlocide. The mixtuce wa6 allowed to 6tic foc 3 h~. The slighly yellow oil cesulting fcom ice-watec quench was isolated by twice ext~acting with ether, followed by dcying of the ocganic layec with Na2S04 to yield 566 mg of a slightly yellow oil which ccystallized slowly (m~ 26-27) aftec chcomatogcaehy (silica gel, chlocofocm). Nmc (CDC13, ~ cel TMS) 1.45-2.3Bm, 4H; 2.72t, 2H: 3.65t, 2H; 6.78-7.12d, 2H;
7.18-7.42, lH. Ic (neat film, v, cm ) 3120w, 29206, 2870m, 1465m, 13706, 1278w, 1260w, 11606, 1075w, 935w, 850w, 830m, 77658, 680m, 625w, 5856, 5356, 5108. El.

i~77989 . .
~nal- Calcd- fo~ C8HllClO2S2 C, 40-25 H~
4.64 Cl, 14.85; S, 26.86. Found: C, 40.23: H, 4.69 Cl, 14.94; s, 26.68.

Example 12 ~ethYl 4-(3-ThienYll-Butane6ulfonate To a 6ti~ed 601ution of 362 mg (1.5x10 3 mol) of the above acid chloeide peepared in Example in 6 ml of freshly di6tilled (from molecula~ ~ieve6) methanol wa6 added, at ~oom temperatu~e, 392 mg (2 equiv) of N,N-diisop~o~ylethylamine. The ceaction mi%tu~e was ~ti~ed fo~ 2 h~ and then t~an6fecred to a ~epa~atory funnel containing dilute, aqueou6 HCl and wa6 ext~acted with chlo~ofoem theice. After the combined S oeganic laye~ we~e deied with Na2S04, the 601vent wa~ evapoeated to affo~d a light brown oil which wa6 eu~ified by ch~omatogeaphy on 6ilica gel with 40% hexane . .in chlo~ofo~m a~ eluent. The ~e6ulting coloele66 oil, obtained in 84S yield had the following p~opeetie6: El.
Anal. Calcd. for C9H14S2O3: C, 46.13; H, 6.02;
S, 27.36. Found: C, 45.97; H, 5.98; S, 27.28. }e (neat film, v, cm~~) 3100w, 2970m, 2860w, 1460m, 1410w, 1350~, 12S0w, 11606, 9825, 830m, 800m, 770~, 710w, 690w, 630w, 613w, 570m. Uv-vis t~max, MeOH, nm (e)] 220 (6.6x10 ). Nmr (CDC13, ~ ~el to TMS) 7.33-7.13 (t, lH), 7.03-6.77 (d, 2H), 3.83 (6, 3H), 3.09 (t, 2H), 2.67 (t,2 H), 2.2-1.5 (m, 4H).

-` 1,'~77~89 ExamPle 13 PolYmeri2ation o~ ThioDhene-3-~cetiC Acid (CH~2COOH
IV

Thiophene-3-acetic acid (Formula IV) was polymerize~ at eoom temperatu~e by the electcochemical polymerization method of S. Hotta et al., SYnth. Metals, auDca, using acetonitrile as the solvent and LiC104 as the electrolyte. ~lue-black films were peoduced, indicating f ormation of the zwitterionic polymer of Pocmula Ia tY1ZH~ R=-CH2, X=C02).
The polymer f ilma were electrochemically cycled and obaerved to undergo a color change from blue-black to yellowish brown, indicating reduction of the zwitterionic form of the polymer to the neutral form repre~ented by Formula I. The infearea spectrum was in agreement with the peopo6ed ~tructure.

:y ~;~77989 ExamPle 14 Polv(Thiophene-3-(2-Ethane6ulfonic Acid Sodium Salt) /(CH2)2S~CH3 V ~ .
~0 (CH ~)2S03CH3 L~
VI \ S

(CH2)2SO3Q Na~
VI I L~:=
\ S

Methyl thiophene-3-~2-ethanesulfonate) (Formula V) was prepaced as above. Polymerization o~ the above monomer wa~ carried out a6 in Example 13, except that the polymerization temperature was maintained at -27C.
The re6ultant polymer (~methyl P3-ETS", Formula VI) was then treated with sodium iodide in acetone to remove the methyl group ~rom the 6ul~onic acid functionality and pcoduce, in quantitative yield (~98~), the corre6ponding 60dium 6alt of the polymer, i.e. of poly(thiophene-3-(2-ethane6ulfonic acid)) (l'P3-ETSNa") a6 ~hown in Formula VII. The polyme~ic methyl e6ter and the polymeric sodium salt were characterized by inf~a~ed and ultraviolet 6pectro6copy as well a6 by elemental '~

~77989 analy6i6 (6ee Fiqure6 1 ana 2). The soaium salt was found to be 601uble in all propoction6 in water, enabling the casting of films from aqueou6 solution.
Elsctrochemical cell6 were con6tructea in glass t

5 to de~on6trate electrochemical doping and charge storage via in situ optoelectcochemical spectroscopy. The cell6, included a ~ilm of the above polymer on IT0-coated glas6 (which servea as the anode), a platinum countecelectrode (cathode) and a silver/silvec chloride reference 10 electrode with tetrabutyla~monium perchlorate as electrolyte. Figure 5 depicts a se~ies of vis-near ir ~pectra of the P3-ETSNa taken with the cell charged to a ~ec~e~ of succe66ively higher open ciccuit voltages.
The ce~ult~ were typical of conducting poly~ers in that 15 the ~-~ tran6ition was depleted with a concomitant ~hift of oscillator 6trength into two chacacteri6tic infra~ed bands. The re6ult6 of Figure 5 de~on~trate both reversible charge ~torage ana electrochro~ism.
The electcical conductivity wa6 measured with the standard 4-probe technigues using a film of the polymer cast fro~ water onto a glass substrate onto which gola contacts had been previously aepo6ited. upon expo~uce to bromine vapor, t~e electrical conductivity of P3-ETSNa ro~e to ~l S/cm.

.~,j .

,: ~",,, . -- ;- - .. ,,;, , ..

~ ~q7989 -2?-ExamDle 15 PolY(ThioDhene-3-(4-Butanesulfonic Acid Sodium Salt~ ) V I I I (CH2)4SO3Me ¢~
S

(CH2)4SO3Mc L~-I X ~S~T

(CH2)4S03O Na6 X \ S

Methyl thiophene-3-(4-butanesulfonate) (Formula VIlIl was prepaced as above. Polymerization was caccied out unaee condition6 identical to those set foeth in Example~ 13 and 14 above. The eesultant polymee (degignated ~methyl P3-aTS", Focmula IX) was treated with sodium iodide in acetone to produce. in quantitative yield, the polyme~ic sodium salt of thiophene-3-(4-butane~ulfonic acid) ("P3-~TSNa", Formula X). The polymeeic methyl este~ (Foemula IX) and the corresponding sodium salt (Formula X) weee chaeactecized ~ ~779~9 spectro6copically (ir, uv-vi6) and by elemental analy6i6. The 60dium 6alt wa6 ai6covered to be 601uble in all propoction6 in water, enabling t~e caE;ting of film6 from aqueou6 solution. t~
Electrochemical cell6 were con6tructed as in Example 14 in o~de~ to demon6trate electrochemical doping and charge 6torage via in ~itu optoelect~ochemical spect~o6copy. Figure6 6 and 7 depict a serie6 of vi6-near i~ spectra of the P3-BTSNa 10 ana methyl P3-BTS re6pectively, taken with the cell6 charged to 6ucce~ively highe~ open ciccuit voltages.
A~ in Example 14, the re6ults were found to be typical of conducting polymers in that the ~-lr tran6ition wa6 depleted with a concomitant shift of oscillator 15 ~trength into two cha~acte~i6tic infra~ed bands. As in Example 14, the re~ult6 of Figure6 6 and 7 demon~tcate both revec~ible charge storage and elect~ochromism.

Exam~le 16 Pol~,rmecization ana Analv6i6 of Polv(ThioDhene-3-Sulfonic Acid)(n~Z~
The polymeric sodium alt of thiophene-3-~ulfonic acid (Formula I, Ht=S, Yl=H, R=-CH2-CH2-, X=S03, M=H)wa~ propa~ea a~ outlined 25 above, di~601ved in water and ~ub~ected to ion exchange chromatogcaphy on the acid for~ of a cation exchange ~e~in. The ~esults of atomic ab~o~ption analy6~6 of the dark red-blown effluent indicated co-~plete reelacement of ~oa~um by hydrogen. Figure 8 show6 the ~e~ult6 of 30 cyclic voltammetcy ca~ied out on film6 of the polymer ("P3-ETSHU/lTO glas~ wo~king electrode, platinum counterelectrode, and a ~ilver/6ilve~ chloriae ~eference elect~ode in acetonitrile with fluo~oboric acia-tri~luoroacetic acid a~ electrolyte). The figu~e ~,77989 indicate6 that P3-ETSH iS an electrochemically cobu6t poly~ec when cycled between ~0.1 and ~1.2~ vec6us 6ilve~/6ilver chlociae in a 6tcongly acidic ~edium.
There are two closely ~paced oxidation wave~. the f iC6t of which coccesponds to a change in color fcom orange to gceen. The polymer could be cycled and cocce~ponding color change6 ob6erved without noticeable change in stability at 100 ~V~6ec.
electcochemical cells wece con6tcucted in gla6s to demonstcate electrochemical doping and charge 6tocage via in situ optoelectrochemical spectcoscopy, substantially a6 in the previous two Example6. The cells con~isted of a film of the polymec on IT0 gla6s tanode)~ platinum countecelectcode (cathode) and a ~ilvec/silver chlociae cefecence electcode in acetonitcile with fluocobocic acid-trifluoroacetic acid a6 electcolyte.
Figuce 9 aepict6 a secie6 of vis-neac ic spectca of the P3-ETSH taken with the cell charged to a secie6 of succe66ively higher open ciccuit voltages. In thi~ case, the polymer wa6 ob6ecved to 6pontaneou61y dope in the ~tcongly acidic electrolyte solution. The ce~ults of Figuce 9 demon~trate both cevecsible chacge ~tocage and electrochro~ . Control of the ~elf-doping level foc bcief pecioas of time wa6 achievea by imposing a voltage lower than the equilibriu~ ciccuit voltage.

exa~Dle 17 PceParation of Polvmec ComPosite Poly(thiophene-3-~ulfonic acia) (Foc~ula I, Ht-S, Y~-H, R=-CH2CH2-, X=S03, M=H, "P3-ETSH") as prepared in Example 16 wa~ u6ed to pcepace a co~po~ite as follow6. The co~pound wa6 admixea with a solution of polyvinyl alcohol in watec, and fil~6 of the ~ 77989 . .
neutral polymee were ca~t. Free 6tanding deep orange ~ilm~ (indicatin~ charge neutrality, a~ oepo~ed to the blue-black zwitterionic polymers) ca~t from the eeepared 601ution had excellent mechanical eropertie~ (~oft, 6mooth and flexible) and could be chemically do~ed and undaped by compen6ation. This method of making conducting polymer comeo6ites i6 broadly applicable to the u6e of any wate~-601uble eolymer in conjunction with P3-ETSH oe P3-BTSH.

ExamPle 18 P eParation of PolYmer of 2~5-DicacboxvethY
1,4-CYclohexanedione and P-PhenYlenediamine To a ~uspension of 8.51g (33.21 mmole) of 2,5-dicarboxyethyl-1,4-cyclohexanedione in 380 ml of ~re~hly di~tilled butanol wa6 added 3.59 9 of ~-ehenylenediamine in 20 ml of butanol, followed by 40 ml of glacial acetic acid. The ce6ulting mixture wa6 heated to reflux for a eeriod of 36 hrs, then it wa6 exposed to oxygen by refluxing over a eeriod of twelve hours, was hot filtered, the 601id wa6 wa~hed with ether and extcacted in a Soxhlet extcactoc with the Sollowing ~olvents: chloroform (6 days), chlorobenzene (5 days), and ether (4 days). This treatment afforded a dark solid (8.42 g). Flemental analys~s calcd. for C18H18N204: C, 65.84; H, 6.14: N, 8.53. Found:
C, 65.55; H, 6.21; N, B.70. Ir (KBc, ~ cm-l): 3350w, 3240w, 2980m, 2900w, 1650s, 16008, 1510~, 1440m, 1400w, 12208, lO90w, 1065s, 820w, 770m, 600w, 495w.

ExamPle 19 PolYaniline DicacboxYlic Acid The above polymec die6ter i8 6u6pended in DMF
and tceated with a 601ution of 50~ (w/w) 60dium 7~989 . .
hydroxide. The reaction mixture is then heated to 100C
for 48 hr under 6trictly anaerobic conditions to exclude oxygen. Upon cooling the mixture, it is eoured into ice/HCl and filtered. The infrared seectrum of the product should show the following characteristic absorption eeaks: 3100-2900br, 1600s, 15008, 12108.

Claims

1. A conducting self-doped polymer having along its backbone a pi-electron conjugated system which comprises a plurality of monomer units, between about 0.01 and 100 mole %
of said units having covalently linked thereto at least one Bronsted acid group.

2. The polymer of claim 1, wherein said monomer units having said Bronsted acid group covalently linked thereto are selected from the following structures (I) or (II):

(I) (II) wherein Ht is a heterogroup selected from the group consisting of NH, S.O. Se and Te, Y1, Y2, Y3 and Y4 are independantly selected from the group consisting of hydrogen and -R-X-M, wherein R is a linear or branched alkyl, ether, ester or amide moiety having between 1 and about 10 carbon atoms and X is a Bronsted acid anion and M is an atom which when oxidized yields a positive monovalent counterion.

(3) The polymer of Claim 2, wherein Ht, Y1, Y2 and Y4 are hydrogen, R is a straight chain alkyl or ether group having between about 1 and 10 carbon atoms, X is CO2 or SO3, and M is selected from the group consisting of H, Li, Na and K.

(4) The polymer of Claim 3, wherein Ht is NH or S, R
is a linear alkyl having from 2 to about 4 carbon atoms, and M is selected from the group consisting of H, Li and Na.

(5) The polymer of Claim 3, wherein said monomer unit having a Bronsted acid group covalently linked thereto is given by the structure of Formula I.

(6) The polymer of Claim 4, wherein said monomer unit having a Bronsted acid group covalently linked thereto is given by the structure of Formula I.

(7) The polymer of Claim 3, wherein said monomer unit having a Bronsted acid group covalently linked thereto is given by the structure of Formula II.

(8) The polymer of Claim 4, wherein said monomer unit having a Bronsted acid group covalently linked thereto is given by the structure of Formula II.

(9) A homopolymer according to Claim 2.

(10) A copolymer according to Claim 2.

(11) A zwitterionic polymer according to Claim 2.

12. The switterionic polymer of claim 1, wherein said monomer units are selected from the following structures Ia IIa wherein Ht is a heterogroup selected from the group consisting of NH, S, O, Se and Te, R is a linear or branched alkyl, ether, ester or amide moiety having between 1 and about 10 carbon atoms and X is a Bronsted acid anion.

13. The switterionic polymer of claim 12, wherein R
is a straight chain alkyl or ether group having between about 1 and 10 carbon atoms and X is CO2 or SO3.

14. The switterionic polymer of claim 13, wherein Ht is HN or S and R is a linear alkyl having from 2 to about 4 carbon atoms.

15. An electrode for use an electrochemical cell, comprising a conductive substrate coated with a polymer according to claim 1.

16. An electrode for use an electrochemical cell, comprising a conductive substrate coated with a polymer according to claim 11.

17. A method of making a self-doped switterionic polymer, comprising the steps of:
providing an electrolyte solution comprising a monomer having the structure wherein Ht is a heterogroup selected from the group consisting of NH, S, O, Se and Te; M is an atom which when oxidized yields a positive monovalent counterion; X is a Bronsted acid group; R is a linear or branched alkyl, ether, ester or amide having between 1 and about 10 carbon atoms;
immersing in said electrolyte solution, a working electrode and a counterelectrode; and applying a voltage across said working electrode and said counterelectrode, whereby polymerization of said monomer at said working electrode is effected to produce a polymer having a recurring structure of the formula.
(18) The method of Claim 17, wherein said polymerization is carried out at a temperature of between about -30°C and about 25°C.
(19) The method of Claim 17, wherein said monomer is selected from the group consisting of thiophene-3-acetic acid, methyl thiphene-3-(2-ethanesulfonate), and methyl thiophene-3-(4-butanesulfonate).
(20) A compound useful in the preparation of conducting polymers comprising methyl thiophene-3-(2-ethanesulfonate).
(21) A compound useful in the preparation of conducting polymers comprising methyl thiophene-3-(4-butanesulfonate).
(22) A method of preparing a self-doping polyaniline, comprising the steps of:
providing a polyaniline diester having the structural formula wherein R is a linear or branched alkyl, ether, ester or amide moiety having between 1 and about 10 carbon atoms and R' is alkyl; and and treating said diester with hydroxide to convert said diester to the corresponding dicarboxylic acid.