Synthesis of poly(dimethylaminoethyl methacrylate) with high cloud point by RAFT polymerization under γ-irradiation

gamma-radiation initiated reversible addition-fragmentation chain transfer (RAFT) polymerization of dimethylaminoethyl methacrylate (DMAEMA) was carried out in acetone/water cosolvent system at room temperature with different chain transfer agents (CTAs). The influence of several parameters, such as the structure of CTAs, the molar ratio of DMAEMA to CTA, DMAEMA concentration, and irradiation conditions, was evaluated with regards to conversion and reaction time, as well as poly(dimethylaminoethyl methacrylate) (PDMAEMA) molecular weight and its distributions. When the dose rate was 20 Gy min(-1) the reaction time could be limited in 100 min with a high conversion. The average molecular weight of PDMAEMA could be controlled from 2733 to 15835 g mol(-1) with polydispersity indices lower than 1.3. The cloud point of the PDMAEMA aqueous solution was also detected to investigate the thermal sensitivity of the resultant PDMAEMA. Compared with the PDMAEMA synthesized through 2,2'-azobis(isobutyronitrile) initiated method, the gamma-ray initiated RAFT mediated PDMAEMA solution has a much higher cloud point (ca. 67 degrees C) than that of former polymer (ca. 37 degrees C) under the same experimental conditions. (C) 2014 Elsevier Ltd. All rights reserved.