Significantly Suppressed Chain Transfer to Monomer Reactions in RAFT Emulsion Polymerization of Styrene

Abstract

The highest accessible molecular weight of the living product in controlled/living radical polymerizations (CLRPs) is determined by the constant of chain transfer to monomer reaction. Thus, the highest molecular weight of living polystyrene had been believed around 100 kg/mol in CLRPs. In our previous report (Yan, K.; Gao, X.; Luo, Y. Well-Defined High Molecular Weight Polystyrene with High Rates and High Livingness Synthesized via Two-Stage RAFT Emulsion Polymerization. Macromol. Rapid Commun. 2015, 36 (13), 1277–1282), we surprisingly found that the livingness of polystyrene of 550 kg/mol could be up to 90% in RAFT emulsion polymerization. Herein, we experimentally measure the constant of chain transfer to monomer reaction in RAFT emulsion polymerization of styrene at various temperatures from 60–80 °C. Very interestingly, it is found that the constant of chain transfer to monomer reaction should be only about one-third of that of the corresponding conventional radical polymerization. From the derived A...