LAUSR

Here, cloud temperature and aggregation behaviors of poly(N-vinyl caprolactam)-based polymer were investigated with the addition of hydrophilic units. Copolymers composed of N-vinyl caprolactam and polyethyleneglycol methylacrylate (POEGMA) were firstly synthesized through a reversible addition fragmentation chain transfer technology with benzylsulfanylthiocarbonylsulfanyl propionic acid (BPA) as chain transfer agent and 4,4′-azobis(4-cyanovaleric acid) as initiator. The cloud points measurements indicated that comparing with pure poly(N-vinyl caprolactam), little amount of POEGMA would dramatically decrease copolymers’ cloud temperature while further addition of POEGMA would inversely increase the cloud temperature. The contribution of POEGMA within polymeric chains was modulated by adding POEGMA after 30 min of initiating polymerization. Both the DLS and TEM measurements showed that micelles instead of random structures were formed through a self-assembling process above the cloud temperature. These results emphasized the importance of the contribution of hydrophilic units in predicting the thermal phase transition behavior of poly(N-vinyl caprolactam)-based materials. Graphical abstract