Living Anionic Polymerization of 5-Substituted 2-Vinylthiophenes

The anionic polymerization of 2-vinylthiophene (1) and four 2-vinylthiophene derivatives (2VTs) possessing various functional groups at the 5-position, 2-methyl-5-vinylthiophene (2), 2-(1-adamantyl)-5-vinylthiophene (3), 2-phenyl-5-vinylthiophene (4), and 2-cyano-5-vinylthiophene (5), was investigated in THF using various initiators. In each case, the resulting polymers had well-defined structures with a controlled molecular weight based on the molar ratio between the monomer and initiator and a narrow molecular weight distribution (MWD, Mw/Mn < 1.2). The stability of the propagating carbanions derived from 3–5 was demonstrated by postpolymerization, whereas partial deactivation of the active species of poly(1) and poly(2) was observed after or during polymerization. The reactivity of 2VTs was significantly affected by the substituents at the 5-position, and the observed substituent effect was similar to that of the corresponding styrene derivatives.