Poly self-doping mechanism

In further studies, the self-doping mechanism of these polymers was verified by cyclic voltammetry, pH measurements and atomic absorption spectroscopy [17,20]. The cyclic voltammograms of the sodium salt and acid forms of poly(3-thiophene butanesulfonate) cast films are shown in... 

Elemental analysis and X-ray fluorescence measurements of films electrochemically oxidized in aqueous KCIO4 solutions, at pH values below the pK of the carboxylic acid indicate the absence of perchlorate counterions in the films [25]. This shows that the oxidized polymer backbone is charge compensated by covalently bound carboxylate anions and confirms the self-doping mechanism of poly( -(3-thienyl)octanoic acid). In contrast to films oxidized in aqueous solutions,... 

Figure 5.32 Self-doping and ion exchange mechanism of poly(3,6-(carhaz-9-yl) propanesulfonate). (Y. J. Qiu, J. R. Reynolds, Journal of the Electrochemical Society, 1990,137, 900. Reproduced hy permission of The Electrochemical Society, Inc.)...

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. 

Figure 20.1. Oxidation of poly(oj-(3-thienyl)alkanesulfonates) illustrating the mechanism of self-doping.

Electrochemical homopolymerization of poly(3-thienyl) acetic acid) and copolymers with thiophene were reported to result in polymers consisting of 2000 monomer units. The films were electrochromic in acetonitrile and exhibited optical transitions between golden yellow (reduced) and blue (oxidized) [26]. Electrochemical polymerization was reported to proceed via a two-dimensional layer-by-layer growth mechanism. The rate of propagation of the film was reported to be 0.008-0.14 S cm [27]. No information pertaining to self-doping was reported. 

Figure 4.39 A proposed mechanism for the self-acid-doping of poly(3-(3 -thienyl-oxy)propanephosphonate). (Reprinted with permission from Langmuir, 19, 2768. Copyright (2003) American Chemical Society.)...

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