Synthesis and Self-Assembly of Polyisobutylene Based Thermoresponsive Diblock Copolymers via Combination of Cationic and RAFT Polymerizations

By the combination of living carbocationic and reversible addition-fragmentation chain transfer (RAFT) polymerizations, a series of well-defined amphiphilic diblock copolymers composed of polyisobutylene (PIB) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) were successfully synthesized. First, cationic polymerization of isobutylene (IB) followed by chain end functionalization gave PIB-macro chain transfer agent, which was subsequently used for block copolymerization with oligo(ethylene glycol) methyl ether methacrylate (OEGMA). Gel permeation chromatography (GPC) confirmed successful and efficient block copolymerzation. The thermoresponsive behaviour of block copolymer aqueous solutions was determined by UV-vis spectroscopy. These block copolymers self-assembled into spherical core-shell nanostructures in an aqueous solution as evidenced by dynamic light scattering (DLS) and scanning electron microscope (SEM).