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 NIPAm monomers. The formations of MOP‐functionalized silica microspheres and PNIPAm‐grafted silica microparticles were characterized by FE‐SEM, TEM, FT‐IR, TGA, and BET. The lower critical solution temperature (LCST) of the PNIPAm‐grafted silica particles was investigated by DSC. magnified image