Silica-core composite particles with poly(N-isopropylacrylamide) (PNIPAM) hydrogel-shell were prepared by using silica microparticle templates, which were modified with [3-(methacryloxy)propyl]trimethoxysilane (MPS). The thenno-responsive PNIPAM hydrogel microcapsules were prepared by soaking the core-shell composite particles in hydrofluoric acid solution. These hydrophilic PNIPAM hydrogel microcapsules were applied to poly(vinylidene fluoride) (PVDF) microfiltration membranes in order to control the hydrophobicity of membrane surface without sacrificing the permeability. PVDF/PNIPAM hydrogel composite membranes were made by phase inversion and diffusion in the mixed solvents of N-rnethyl-2-pyrrolidone (NMP) and ethylene glycol monomethyl ether (EGME) with polyethylene glycol 600 (PEG 600) as plasticizer. (C) Koninklijke Brill NV, Leiden, 2009