Towards smart polymeric drug carriers: self-assembling γ-substituted polycaprolactones with highly tunable thermoresponsive behavior

Synthesis and ring opening polymerization of a new g-substituted epsilon-caprolactone monomer, gamma-(2-methoxyethoxy)-epsilon-caprolactone is reported. Amphiphilic diblock copolymers comprised of poly[gamma-(2-methoxyethoxy)-epsilon-caprolactone] and thermosensitive poly{gamma-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-epsilon-caprolactone} as the hydrophobic and hydrophilic blocks, respectively, were prepared. The copolymers exhibited fully biodegradable backbones and highly tunable thermoresponsive behavior in the range of 31-43 degrees C. Additionally, the copolymers were shown to self-assemble in aqueous media above their respective critical micelle concentrations, on the order of 10(-2) g L-1. Due to their thermosensitive, self-assembling, and biodegradable properties, these copolymers demonstrate potential for the use in polymeric micellar drug delivery systems.