Preparation of monodisperse poly(N-isopropylacrylamide) microspheres and microcapsules via Shirasu-porous-glass membrane emulsification

We have successfully prepared monodisperse poly(N-isopropylacrylamide) (PNIPAM) microspheres and hollow microcapsules by employing monomer-contained water-in-oil (W/O) emulsions as the polymerizing templates and introducing proper initiators into the disperse water phase or continuous oil phase, respectively. First, monodisperse monomer-contained W/O emulsions were prepared by SPG membrane emulsification method; then, UV irradiation was used to polymerize the monomer-contained W/O emulsions at a temperature below the lower critical solution temperature of PNIPAM. The prepared PNIPAM microspheres and hollow microcapsules were featured with good monodispersity and excellent thermo-responsive properties. The preparation methodology demonstrated in this study provided a unique approach for preparing monodisperse microspheres and hollow microcapsules with single W/O emulsions.