Poly alkylsulfonic acids

Figure 6 Aggregation numte Z as function of Na and for various block copolymer/solvent systons poly(styrene-l>-4-vinylpyridine)/toluene (o), poly(st3Tene-fc-methacrylic acid)/ dioxane-water ( ), poly(methacrylic acid-i>-styrene-i>-metha-crylic acid)/dioxane-water (A), poly(styrene-cn-maleic anhydride- -ethylene oxide)/watCT (V), alkyl ethylene glycol/ water ( ), alkylammonium bromide/water ( ), alkylsulfonate/ water (s), alkylsulfate/water (a). The solid line corresponds to the relation Z = (Reproduced from Ref. 2. Wiley-...

Heteroaromatic systems, such as the widely used poly(thiophene)s can be obtained by simple oxidative polymerization of the soluble monomers or oligomers either by electrochemical means or oxidizing agent such as FeCla [50,51]. This common route is also used to synthesize a variety of mono- and dialkyl-, -alkoxy-, and -alkylsulfonic acid substituted and therefore soluble poly(thiophene)s [52-57] (Scheme 19) and can also be utilized to obtain poly(pyrrole)s. The disadvantage of this polymerization methods however is the regiorandom structure of the polymeric product with non-reproducible properties. 

Finally, we mention some other attempts that have been directed toward the preparation of copolymers poly(aniline-co-o//w-toluidine) [732, 733], poly(aniline-cothiophene) [734], poly(aniline-co-aniline with sulfonate, alkylsulfonate, carboxy-late, chloro and fluoro groups) [735], poly(aniline-co-/7-phenylene diamine) [737], poly(aniline-co-w-phenylenediamine) [736, 738], poly(aniline-co-diphenyl-amine) [164,360,739], poly(aniline-co-dithioaniline [740], as well as copolymers of diphenylamine and anthranilic acid [361] or benzidine [349], iV-vinylcarbazole and thienylpyrrole and terthiophenes [618], and aniline with aminonaphthalenesul-fonates [243]. Several other works that describe copolymers can be found among... 

Electrochemical homopolymerization of poly(aniline-N-alkylsulfonates) (alkyl = propyl, butyl and pentyl) in acetonitrile containing 0.1 M NaC104 and 5 % (v/v) 0.3 M HCIO4 was carried out by Rhee et al. [144]. The polymers were prepared on a platinum electrode by cyclic voltammetry (0.0 to 1.0 V vs Ag/AgCl) or potentiostatic techniques (1.0 V). These polymers were found to form liquid crystalline solutions in water. The conductivity of poly(aniline-N-propanesulfonic acid) and poly(aniline-N-butanesulfonic acid) was reportly 9 x 10 and 6 x 10 S/cm, respectively. Electrochemical polymerization of orthanilic acid, metanilic acid and sulfonic acid and their copolymerization with aniline in dimethyl sulfoxide containing tetrabutyl ammonium perchlorate were carried out by Sahin et al. [145]. These polymers and copolymers were found to be soluble in water, dimethyl sulfoxide and N-methylpyrrolidinone. The conductivity of orthanilic acid, metanilic acid and sulfonic acid was reportly 0.052,0.087 and 0.009 S/cm, respectively. The conductivity of copolymers for these three isomers of aminobenzene-sulfonic acid was reported as 0.094, 0.26 and 0.033 S/cm, respectively. Sahin et al. [146] have also prepared the copolymers of these three isomers with aniline in acetonitrile containing fluorosulfonic acid (FSO3H). The copolymers were found to be soluble in water, dimethyl sulfoxide and N-methylpyrrolidinone. 

Other 3-substituted thiophenes that have been polymerized include 3-methoxy [309-311], other 3-alkoxy [312], 3-phenyl [313,314], 3-(4-methoxyphenyl) [314], 3-(4-trifluoromethylphenyl) [314], 3-bromo [315], 3-alkylsulfonatethiophene [316-318], and others [319-323]. Poly-3-alkylsulfonate thiophenes are particularly interesting due to a striking property. Sodium poly-3-thiophene-j8-ethanesulfonate and sodium poly-3-thiophene-6-butanesulfonate and their conjugate acids are water soluble in both the doped and undoped states [317,318]. Ikenoue et al. [318] examined the conduction mechanism for this self-doped conducting polymer. 

Self-doping has also been studied with poly(3-alkylsulfonate-thiophenes) [7-9]. The self-doped polythiophenes have a SO3H group at the end of the alkyl side chain. However, in order to obtain good conductivities, the charge transfer reaction has to be driven electrochemically to remove the cation (H+ or Na+) of the sulfonic acid out of the polymer. Otherwise this kind of self-doped polythiophenes have a very low conductivity in the dried state due to the protonation of the thiophene rings [75]. 

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