Tetrathiafulvalene (TTF)-Functionalized Thiophene Copolymerized with 3,3′-Didodecylquaterthiophene: Synthesis, TTF Trapping Activity, and Response to Trinitrotoluene

We report a synthesis route to a thiophene polymer where the repeat unit consists of 3,3'''-didodecylquaterthiophene (as in PQT12) plus an additional thiophene ring from which other functional groups may be projected. The hydroxymethyl form of this polymer, while only a poor semiconductor in its own right, serves as a vehicle for compatibilizing PQT12 itself with arbitrary functional groups. In this article, we focus on tetrathiafulvalene (TTF) as the functionality. As expected, the TTF group acts as a hole trap, as shown by loss of hole mobility and a surprising negative Seebeck coefficient, but this enables a current-increase response to trinitrotoluene as an analyte and confirms a similar observation we recently reported for a dissolved TTF. Added dopants also fill the trap states, restoring hole mobility and the typical positive Seebeck coefficient.