Synthesis and Characterization of Poly(N-isopropylacrylamide)/Silica Composite Microspheres via Inverse Pickering Suspension Polymerization

In this paper, stable poly (N-isopropylacrylamide)/silica composite microspheres are successfully synthesized via inverse Pickering suspension polymerization using various sizes of silica particles as stabilizers. The droplets of N-isopropylacrylamide aqueous solution were first dispersed in toluene and stabilized by silica particles, and then polymerized to obtain poly (N-isopropylacrylamide)/silica composite microspheres. Preliminary studies show that these PNIPAm/silica composite microspheres have similar thermal-responsive behavior as pure microgels with the LCST of 32 degrees C. The releasing property of the composite microspheres can be either controlled by the particle size of the silica or the temperature.