Synthesis of three- and six-arms polystyrene via living/controlled free radical polymerisation

Three new polyfunctional TEMPO-based initiators have been synthesised by re action of some mesitylene cores and 2,2,6,6-tetramethyl-1-(2-hydroxy-1-phen ylethoxy)-piperidine. They have been employed in the living/controlled radi cal polymerisation of styrene to provide three- and six-arm star macromolec ules. These polymers have molecular weight ranging from 6000 to 11000 g/mol and narrow molecular weight distributions (PD < 1.3). Cleavage of the link between the core and the arms was achieved, using a two-step sequence impl ying the preliminary removal of the TEMPO chain ends followed by catalytic hydrogenolysis. The dimensions of the individual arms so obtained closely m atch the values expected from the styrene/initiator molar ratio in the poly merisation feed. (C) 2001 Elsevier Science Ltd. All rights reserved.