Preparation and characterization of modified nanosilica/PNIPAm hybrid cryogels

A series of macroporous hybrid cryogels based on poly(N-isopropylacrylamide) (PNIPAm) were synthesized by free radical polymerization in the presence of organically modified nanosilica. To improve the interaction of silica nanoparticles with polymer structure, the silica surface was first treated with 3-methacryloxypropyltrimethoxysilane (MPTMS). Then a series of hybrid cryogels each containing 1 wt.% nanosilica and various amounts of MPTMS (1-4 wt.% to monomer NIPAm) were prepared. The yield of methacrylate modification of the nanosilica surface determined by TGA analysis was 11.2 wt.%. The particle size distribution of modified nanosilica particles was investigated by dynamic light scattering technique (DLS) and the mean particle diameter with respect to number was found as 68 nm. The morphology of cryogels was evaluated by SEM. The improvement in the thermal and mechanical properties using the addition of modified silica nanoparticles was achieved.