Alkoxyamine-mediated "living" radical polymerization: MS investigation of the early stages of styrene polymerization initiated by cumyl-TEISO

A new series of 1,1,3,3-tetraethylisoindoline-2-oxyl (TEISO)-based alkoxyam ines was prepared. The half-lives for thermal dissociation indicated that t he most sterically congested cumyl-TEISO alkoxymine had the greatest potent ial as an initiator for the polymerization of monomers at lower temperature s. The polymerization of styrene at 110 degreesC gave a linear evolution of M-n with conversion in the early stages. Further evidence for the "living" nature was given by the polydispersities of the polymers that remained low (M-w/M-n = 1.13-1.27) throughout the polymerization (up to 80% conversion) . No polymer was formed for the styrene system in a reasonable time below 1 00 degreesC. High-performance liquid chromatographic/mass spectrometric inv estigations of the distribution of trapped oligomers containing one to nine monomer units formed at 60 degreesC revealed that the trapping of oligomer ic cumyl-styryl radicals by TEISO is irreversible at this temperature. Meth yl methacrylate polymerized with cumyl-TEISO at 60-70 degreesC, although th e initial high rates of polymerization soon decreased to zero at low conver sions (10-15%), and the high polydispersities (M-w/M-n = 1.42-1.73) indicat ed significant side reactions. (C) 2001 John Wiley & Sons, Inc.