Macromolecules, Vol.32, No.16, 5313-5320, 1999
Electrochemical synthesis and characterization studies of poly[3,3 '-dialkylsulfanyl-2,2 '-bithiophene] films
Of the numerous thiophene derivatives, 3-alkylsulfanylthiophenes (3AST) is one of the few that cannot be readily polymerized electrochemically to afford the corresponding conductive polymer films. We demonstrate in this paper that 3,3'-dialkylsulfanyl-2,2'-bithiophenes are appropriate monomers into polythiophenes incorporating pendant alkylsulfanyl moieties. Facile electrochemical polymerization can be effected by both the potentiostatic and galvatiostatic approach. The resulting polymer films have molecular weighs (M-n) of ca. 3600 and were soluble in common solvents. Characterization by NMR, UV-vis spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy are described. The polymers depicted a low-energy pi-pi* transition despite the high steric effects present in such HH-TT polythiophenes. In direct contrast to poly[3,3'-dialkyl-2,2'-bithiophene]s and poly[3,3'-dialkoxy-2,2'-bithiophene]s, PDASBTs exhibited significant thermochromistic effects. More significantly, the polymer films exhibited facile electrochemical oxidative (p-) and reductive (n-) doping which are of importance in the practical applications of electrically conductive polymers in rechargeable batteries and other electronic devices.
Keywords:STRUCTURE-PROPERTY RELATIONSHIPS;ELECTROACTIVE POLYBITHIOPHENEDERIVATIVES;STABLE CONDUCTING POLYMERS;SUBSTITUTEDPOLYTHIOPHENES;ELECTRONIC-PROPERTIES;OPTICAL-PROPERTIES;DOPING PROPERTIES;DESIGN;COPOLYMERS;POLY(3-ALKYLTHIOPHENES)