Synthesis of Arborescent (Dendritic) Polystyrenes via Controlled Inimer-Type Reversible Addition-Fragmentation Chain Transfer Polymerization

The reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and 4-vinylbenzyl dithiobenzoate, a RAFT-based inimer (initiatormonomer), is described. Controlled polymerization was achieved in bulk conditions using thermal initiation at 110 degrees C to give arborescent polystyrene (arbPSt). The number-average molecular weights of the polymers increased linearly with conversion and were much higher than theoretically calculated for a linear polymerization, reaching M-n = 364,000 g/mol with M-w/M-n = 2.65. Branching analysis by NMR showed an average of 3.5 branches per chain. SEC data, which were similar to those measured in arborescent polyisobutylene, supported the architectural analysis. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7621-7627, 2008