COMPOSITES OF THERMO-RESPONSIVE PNIPAM AND MESOPOROUS SILICA MICROPARTICLES USING MOP-MODIFIED SILICA PARTICLES PREPARED BY EMULSION-GEL METHOD

Abstract

The composites of Poly(N-isopropylacrylamide) (PNIPAm) and mesoporous silica micro-spheres were synthesized using 3-(trimethoxysilyl) propyl methacrylate (MOP) as a silane coupling agent. First, MOP-modified silica particles with 1-3 mm were prepared by the sequential addition of tetraethyl orthosilicate (TEOS) and MOP into W/O emulsion consisting of aqueous solution of SDS or Tween 20 and n-octanol of hydroxypropyl cellulose (HPC) and Span 80. The effect of MOP on the formation of the silica particles was investigated by the variation of the reaction time of TEOS before the addition of MOP. Second, PNIPAm-grafted mesoporous silica micro-spheres were synthesized by radical copolymerization of MOP-modified silica particles, NIPAm monomers and N,N’-methylene bisacrylamide (MBAA) in water at 70℃ for 24 h. The effect of cross-linker was studied by controlling the [NIPAm] : [MBAA] molar ratio. The formations of MOP-silica and PNIPAm-silica composites were investigated by FT-IR, BET, FE-SEM and TGA. The phase transition of prepared thermo-responsive polymers was characterized by DSC.