Monodisperse microspheres （mean diameter 200-300 nm） with polystyrene cores and poly（acrylamide-co-butyl methacrylate） shells were prepared by using a free radical polymerization method. Moreover, the effect of mixed solvent on the preparation, morphology and monodispersity was investigated. The experimental results showed that solubility parameter of butyl methacrylate and solvent affected mainly the molding of monodisperse core-shell microspheres. When the microspheres were fabricated in a sequential synthesis process, addition of hydrophilic and organic solvent including butyl methacrylate led to spherical degree of the particles becoming worse, and the mean diameter of the microspheres decreased and the monodispersity became better with increasing the crosslinker methylenebisacrylamide dosage.
A novel thermo-responsive hydrogel column, featured with both ends of linear poly（N- isopropylacrylarnide） （PNIPAM） chains being grafted onto cross-linked PNIPAM chains, was reported. The laterally sandwich-typed hydrogel columns were fabricated by radical polymerization in a three-step process using a method of ice-melting synthesis. The initiating path, morphology and thermoresponsive characteristics of the prepared hydrogel columns were experimentally studied. The results show that the hydrogel column obtained by the initiator inside part has more quick swelling and deswelling rates responsing to temperature cycling than other hydrogels owing to linear PNIPAM chains to form supermacroporous structure. The proposed hydrogel structure provide a new mode of the phase transition behavior for thermo-sensitive ＂smart＂ or ＂intelligent＂ monodisperse micro-actuators, which is highly attractive for targeting drug delivery systems, chemical separations, and sensors and so on.
A novel poly（N-isopropylacrylamide）-based sandwich-typed hydrogel, which was featured with both ends of linear poly（N-isopropylaerylamide） （PNIPAM） chains being grafted onto cross-linked PNIPAM chains, was successfully prepared in a three-step process by a method of sequential synthesis. The proposed hydrogel displays faster and hydration/dehydration dynamic response to temperature cycling owing to linear PNIPAM chains to form big-pore structure. This work may lead to high attraction for targeting drug delivery systems, polymeric pump, sensors and so on.
