Stable free-radical copolymerization of styrene with acrylates using OH-TEMPO

Stable free-radical copolymerizations (SFRP) or styrene with N-acryloyl morpholine (AMo), 2-ethoxyethyl acrylate (EOEA) and isobornyl acrylate (iBoA), respectively, were carried out under control of the stable nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (OH-TEMPO). The polymerizations were initiated by a polystyrene macroinitiator (PS-MI). No accelerating agents were used. In contrast to the experiences made with methacrylates there was no decrease in the polymerization rates up to 50 mol-% of AMo or EOEA in the monomer mixture. This behavior was ascribed to a compensation of the lack of thermal initiation by the high propagation rate constants of the acrylates. The produced AB diblock polymers were successfully employed in block extension reactions in styrene yielding ABA triblock polymers. Copolymerization reactivity ratios (r-values) and glass transition temperatures have been estimated.