Investigation of the effect of substituent on the growth of polymer for 3-substituted polythiophenes via pyrolysis mass spectrometry

In this study, direct pyrolysis mass spectrometry analyses of electrochemically polymerized poly(decanedioic acid bis-(2-thiophen-3-yl-ethyl)ester) and poly(terepthalic acid bis-(2-thiophen-3-yl-ethyl)ester) were performed to investigate structural and thermal characteristics. It was found that when the ester linkages contain hydrocarbon chains, the growth of polymer occurred through both 2- and 5-positions. On the other hand, when the ester linkages contain more rigid groups such as phenyl, steric hindrance inhibited the growth of the polymer through 2-position and polymerization proceeded via coupling of thiophene moieties mainly at 5-position yielding a polymer with a lower conductivity.