Iron-mediated (dual) concurrent ATRP–RAFT polymerization of water-soluble poly(ethylene glycol) monomethyl ether methacrylate

Abstract

In this work, the iron-mediated (dual) concurrent ATRP–RAFT polymerization of water-soluble poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) was investigated at different polymerization temperatures (from 90 °C to 30 °C), using 2-cyanoprop-2-yl-1-dithionaphthalate (CPDN) as an alkyl pseudohalide initiator, ethyl 2-bromoisobutyrate (EBiB) as a co-initiator, and FeCl₃·6H₂O/PPh₃ complex as the catalyst. The polymerization kinetics was studied in detail at polymerization temperatures of 90 °C and 30 °C. The results showed that the concurrent ATRP–RAFT polymerization (using only CPDN as the initiator) of PEGMA could be carried out successfully, even if the polymerization temperature was reduced to 30 °C. Furthermore, the polymerization rate was remarkably enhanced via dual concurrent ATRP–RAFT polymerization (using CPDN and EBiB as co-initiators). For example, the monomer conversion could be higher than 70% in the dual concurrent ATRP–RAFT polymerization system in 65.5 h, while a conversion of only 22% could be obtained after 167 h for the concurrent ATRP–RAFT polymerization system at 30 °C. The “living” features of dual concurrent ATRP–RAFT polymerization of PEGMA were verified by chain end analysis and chain-extension experiments.