Thermo-Responsive and Biocompatible Diblock Copolymers Prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) Radical Polymerization

Abstract: Poly(2-(methacryloyloxy)ethyl phosphorylcholine)-b-poly(N,N-diethyl acrylamide) (PMPC_m-PDEA_n) was synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization. Below, the critical aggregation temperature (CAT) the diblock copolymer dissolved in water as a unimer with a hydrodynamic radius (R_h) of ca. 5 nm. Above the CAT the diblock copolymers formed polymer micelles composed of a PDEA core and biocompatible PMPC shells, due to hydrophobic self-aggregation of the thermo-responsive PDEA block. A fluorescence probe study showed that small hydrophobic small guest molecules could be incorporated into the core of the polymer micelle above the CAT. The incorporated guest molecules were released from the core into the bulk aqueous phase when the temperature decreased to values below the CAT because of micelle dissociation.