Synthesis of Six-Arm Star Polymer by Nitroxide-Mediated “Living” Radical Polymerization

Abstract

A dendritic multifunctional initiator with 6 TEMPO-based alkoxyamine moieties was prepared from 4-bromophenylethylbenzene in 7 steps and 6-arm star polymers were prepared by the radical polymerization of styrene (St) using the dendritic alkoxyamine as an initiator. The St polymerizations were carried out at 120°C using the dendritic alkoxyamine concentrations of 5.0, 12.8, and 18.8 mmol L -1 When the alkoxyamine concentration was 5.0 mmol L -1 , the polydispersity indexes of the resulting star polymers increased with conversion and that of the star polymer at 72% conversion was 1.59. On the other hand, when the alkoxyamine concentrations were 12.8 and 18.8 mmol L -1 , the polymerization was well controlled to give star polymers with a low polydispersity index even at high conversion. The side reactions disturbing the living fashion were discussed on the basis of the SEC elution curves of the star polymers obtained.