Thermal stability and kinetic study of conductive polymers containing phenylene and bithiophene units

A series of conductive polymers containing alternating phenylene and substituted bithiophene repeat units was synthesized and studied using thermogravimetry (TG). Polymers with longer substituted alkyl chains exhibit lower thermal stability compared to those with shorter alkyl chains. Activation energies obtained by the Kissingerʹs method gave support to this observation. Poly[1,4-bis(3-octyl-2-thienyl)phenylene] (PBTBC8), one of the polymers in the series, was also studied under isothermal conditions and the activation energies obtained agreed quite well with those from dynamic TG. The thermal stability of polymers in the doped state was also studied and the adverse effect caused by dopant was less pronounced compared to the polyalkylthiophenes reported in the literature.