Photochemical polymerization of oligothiophene and dithienothiophene

Photochemical polymerization of oligothiophenes and dithienothiophenes were investigated. Photo-irradiation to solutions containing a series of the thiophene derivatives and appropriate electron acceptor gave α-linked polymers having molecular weight of about 104 (vs. PSt). In the case of oligothiophenes, cation radicals of the monomers were efficiently generated through the photoinduced electron transfer from the triplet excited state to the electron acceptor. Then the successive coupling reaction resulted in a formation of polymeric products. On the other hand, photoinduced electron transfer from singlet excited state of dithienothiophenes to electron acceptor was suggested as a generation mechanism of their cation radicals.