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

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.