Amphiphilic Triblock Copolycarbonates with Poly(glycerol carbonate) as Hydrophilic Blocks

Amphiphilic triblock copolycarbonates poly(glycerol carbonate-b-DTC-b-glycerol carbonate) with poly(glycerol carbonate) chains as the hydrophilic blocks were designed and synthesized. In the first step, the PDTC diol macroinitiators were synthesized via bulk polymerization of DTC with 1,6-hexanediol as an initiator and Sn(Oct)(2) as a catalyst. Then the amphiphilic triblock copolycarbonates were synthesized via cationic ring-opening polymerization of 2-benzyloxytrimethylene carbonate (BTMC) with PDTC diol as a macroinitiator and fumaric acid as a catalyst, followed by a hydrogenolytic deprotection reaction with Pd-C as a catalyst in an autoclave. The amphiphilic triblock copolymers were characterized by H-1 NMR, C-13 NMR, GPC, DSC, and water contact angle. The self-assemble behavior of the amphiphilic triblock copolycarbonate in deuterated solvents monitored by H-1 NMR showed a strong incompatibility of the two segments. Stable micelle solution of the amphiphilic triblock copolycarbonate in water was prepared by adding water to a THF solution of the polymer followed by removal of the organic solvent by rota-evaporation. Dynamic light scattering measurement showed that the micelle had a narrow unimodal size distribution. Drug-loading properties of the copolycarbonate micelles were tested with prednisone acetate as a model drug.