Microwave-assisted one-step synthesis of poly(2-isopropyl-2-oxazoline) block copolymers using a dual initiator for CROP and RAFT polymerization

This paper reports the microwave-assisted, rapid, one-step synthesis of poly(2-isopropyl-2-oxazoline) (PiPrOx) block copolymers using 4-cyano-4-(dodecylthiocarbonothioylthio) pentyl-4-methylbenzenesulfonate (CDPS) and 4-cyano-4-(dodecylthiocarbonothioylthio)pentyl-4-nitrobenzenesulfonate (CDPN) dual initiators for reversible addition-fragmentation chain-transfer (RAFT) polymerization and cationic ring opening polymerization (CROP). Kinetic investigations of the CROP of 2-isopropyl-2-oxazoline (iPrOx) initiated with CDPS and CDPN were conducted. The CROP of iPrOx initiated with CDPS did not follow first-order kinetics due to the slow initiation reaction, whereas the CROP of iPrOx initiated with CDPN followed first-order kinetics due to the fast and efficient initiation reaction. PiPrOx-b-poly(N,N-dimethylacrylamide) (PiPrOx-b-PDMA) block copolymers were synthesized using CDPN at 140 °C in a one-step procedure under microwave irradiation. The resulting PiPrOx-b-PDMA block copolymers showed narrow molecular weight distributions. Overall, CDPN is a useful dual initiator for the microwave-assisted one-step synthesis of PiPrOx block copolymers.