Low-Temperature Synthesis of Thermoresponsive Diblock Copolymer Nano-Objects via Aqueous Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA) using Thermoresponsive Macro-RAFT Agents

摘要

Photoinitiated reversible addition-fragmentation chain transfer ( RAFT) dispersion polymerization of 2-hydroxypropyl methacrylate is conducted in water at low temperature using thermoresponsive copolymers of 2-(2-methoxyethoxy) ethyl methacrylate and oligo( ethylene glycol) methacrylate ( M-n = 475 g mol(-1)) as the macro-RAFT agent. Kinetic studies confirm that quantitative monomer conversion is achieved within 15 min of visiblelight irradiation (405 nm, 0.5 mW cm(-2)), and good control is maintained during the polymerization. The polymerization can be temporally controlled by a simple "ON/OFF" switch of the light source. Finally, thermoresponsive diblock copolymer nano-objects with a diverse set of complex morphologies (spheres, worms, and vesicles) are prepared using this particular formulation.