Novel Thermoresponsive and pH-Responsive Aggregates from Self-Assembly of Triblock Copolymer PSMA-b-PNIPAAm-b-PSMA

A series of novel triblock copolymers of poly(stearyl methacrylate)- b -poly( N -isopropylacrylamide)- b -poly(stearyl methacrylate) (PSMA- b -PNIPAAm- b -PSMA) with different molecular weights was synthesized through carboxyl-terminated trithiocarbonates as a highly efficient RAFT agent via reversible addition−fragmentation chain transfer (RAFT) polymerization. The resultant polymers were characterized by 1 H NMR, FT-IR spectroscopy, and GPC. By varying the organic solvent used in the self-assembly procedure and adjusting the copolymer composition, multiple morphologies ranging from vesicles and core−shell spherical aggregates with different dimensions to pearl-necklace-like aggregates were obtained. The aggregates showed thermoresponsive and pH-responsive properties through the lower critical solution temperature (LCST) of PNIPAAm and the two carboxyl end groups of the copolymer.