Porous microspheres of methoxy poly(ethylene glycol)-b-poly(ɛ-caprolactone-co-d,l-lactide) prepared by a melt dispersion method

Surfactant-free biodegradable porous microspheres of methoxy poly(ethylene glycol)-b-poly(ɛ-caprolactone-co-d,l-lactide) (MPEG-b-PCLDLL) diblock copolymers were prepared by a simple melt dispersion method in water at 80 °C with magnetic stirring. Any organic solvents and surfactants can be neglected for this method. Different CL/DLL ratios in the MPEG-b-PCLDLL were investigated for preparation of the porous microspheres. It was found that microsphere sizes decreased and surface pore sizes increased as the increasing DLL ratio. The pores were well interconnected throughout the microsphere matrices for all MPEG-b-PCLDLLs. The larger pore sizes can be obtained when the PEG was blended with diblock copolymer before preparation of porous blended microspheres. Possible mechanisms for formation of the porous microspheres with and without PEG blending were also proposed.