Tunable, Concentration-Independent, Sharp, Hysteresis-Free UCST Phase Transition from Poly(N-Acryloyl Glycinamide-Acrylonitrile) System

Poly(N-acryloylglycinamide-co-acrylonitrile)(poly(NAGA-AN)) copolymers were synthesized using reversible-addition-fragmentation transfer polymerization. In contrast to poly(NAGA) the thermoresponsive behavior of poly(NAGA-AN) shows a narrow cooling/heating hysteresis in water with a tunable cloud point, depending on the acrylonitrile amount in polymer. Furthermore, we showed that there is no significant effect of the solution concentration on the cloud point and stable phase transition behavior in electrolyte solutions, which is presumable controlled by forming stable micellar like structures as a result of the block/graft-copolymer structure. This is in contrast to poly(NAGA) which shows a strong concentration dependent cloud point in aqueous solution with a broad cooling/heating hysteresis. (C) 2016 Wiley Periodicals, Inc.