Synthesis and Self-Assembly of Biodegradable Poly(ethylene oxide)-b- Polycaprolactone (PEO-b-PCL) Diblock Copolymers

A series of amphiphilic poly(ethylene oxide)-bpolycaprolactone (PEO-b-PCL) diblock copolymers had been synthesized by ring-opening or sequential anionic living polymerization. Nuclear Magnetic Resonance (NMR) and gel permeation chromatography (GPC) were used to characterize these copolymers. All copolymers have polydispersity index (PDI) from 1.14 to 1.37 by GPC. Two self-assembly techniques, film rehydration and organic solvent extraction, had been employed to process polymersomes. The perfect nanostructured polymersomes were processed by freeze-thaw- sonication film rehydration technique. The polymersomes with sizes from a hundred nanometer to several microns were obtained from these copolymers. Polymersomes could only be made from the copolymers with PEO blocks (Mn: 2k-3.8k) and fPEO (11.818.8%). Film rehydration is a highly favorable selfassembly method for preparing biodegradable nanostructured polymersomes.