Preparation of thermosensitive PNIPAm-Grafted mesoporous silica particles

In this study, the composites of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) and mesoporous silica particles were synthesized. 3-(Trimethoxysilyl)propyl methacrylate (MOP) was used to introduce double bonds on silica particles. First, MOP-modified spherical silica particles were prepared by the sequential addition of tetraethyl orthosilicate (TEOS) and MOP into W/O (water-in-oil) emulsion. Second, PNIPAm-grafted silica microparticles were synthesized by the radical copolymerization of MOP-modified silica particles and N-isopropylacrylamide (NIPAm) monomers in the ethanol/water mixture. Polymerization was carried out with the variation of reaction temperature, concentration of crosslinking agent, and weight ratio of MOP-modified silica particles to NIPArn monomers. The formations of MOP-functionalized silica microspheres and PNIPAm-grafted silica microparticles were characterized by FE-SEM, TEM, FTIR, TGA, and BET. The lower critical solution temperature (LCST) of the PNIPAm-grafted silica particles was investigated by DSC.