Novel preparation of PNIPAm-grafted hollow silica particles

Abstract

In this study, the composites of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) and mesoporous hollow silica particles were synthesized. 3-(trimethoxysilyl) propyl methacrylate (MOP) was introduced onto the surface and inner surface of hollow silica particles by the sequential addition of tetraethyl orthosilicate (TEOS) and MOP in a W/O emulsion. The experiments were conducted with various concentration of cross-linking agent (MBA : N,N’-methylenebisacrylamide) and the ratio of N-isopropylacrylamide (NIPAm) monomer at 70°C to prepare PNIPAm-grafted hollow silica particles. Interestingly inner and outer surface of particles including PNIPAm was synthesized by radical copolymerization of NIPAm monomers with MOP-modified hollow silica particles. Also loading and release experiments of Safranin-O were conducted using a PNIPAm-grafted hollow silica particles. Safranin-O released from the PNIPAm-grafted hollow silica particles responded by changing of the external temperature. The PNIPAm-grafted hollow silica composites were confirmed by FT-IR, FE-SEM, TEM and TGA. The lower critical solution temperature (LCST) of the PNIPAm-grafted hollow silica particles was investigated by DSC. Release of Safranin-O at PNIPAm-grafted hollow silica particles were confirmed by UV.