Nitroxide-mediated homopolymerization and copolymerization of 2-vinylpyridine with styrene

Homopolymerization and copolymerization of 2-vinylpyridine (2VP) with styrene (S) at 125 degreesC in the presence of 2,2,6,6-tetramethyl piperidin-1-yloxyl (TEMPO) radicals have been studied. The homopolymerization was carried out with 2,2'-azobis-(isobutyronitrile) (AIBN) as a thermal initiator or without AIBN in the initial reaction mixture. In the copolymerization initiated with AIBN, the molar fraction of 2VP in the feed, F-2VP, varied in the range of 0.1-0.9; F-2VP = 0.65 was found to be the azeotropic composition. The linear semilogarithmic time- conversion plots demonstrated a pseudo-living nature of the polymerizations under study. The molecular weight-conversion dependences indicated the participation of side reactions, diminishing the number of TEMPO-terminated polymer chains. The synthesized homopolymers and copolymers were characterized using size-exclusion chromatography (SEC), nitrogen analysis, and NMR spectroscopy. (C) 2001 John Wiley & Sons, Inc.