Highly efficient reversible addition–fragmentation chain-transfer polymerization in ethanol/water via flow chemistry

Utilization of a flow reactor under high pressure allows highly efficient polymer synthesis via reversible addition–fragmentation chain-transfer (RAFT) polymerization in an aqueous system. Compared with the batch reaction, the flow reactor allows the RAFT polymerization to be performed in a high-efficiency manner at the same temperature. The adjustable pressure of the system allows further elevation of the reaction temperature and hence faster polymerization. Other reaction parameters, such as flow rate and initiator concentration, were also well studied to tune the monomer conversion and the molar mass dispersity (Đ) of the obtained polymers. Gel permeation chromatography, nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopies (FTIR) were utilized to monitor the polymerization process. With the initiator concentration of 0.15 mmol L⁻¹, polymerization of poly(ethylene glycol) methyl ether methacrylate with monomer conversion of 52% at 100 °C under 73 bar can be achieved within 40 min with narrow molar mass dispersity (D) Đ (<1.25). The strategy developed here provides a method to produce well-defined polymers via RAFT polymerization with high efficiency in a continuous manner.