Polyurethane/silica composites, prepared via in-situ polymerization in the presence of chemically modified silicas

A hydrophilic fumed nanosilica surface was modified with γ-glycidoxypropyltrimethoxysilane, and subsequently with diethanolamine. The chemically modified silicas were used for the in-situ preparation of polyurethane/silica composites. The doubly modified silica gave rise to a greater enhancement of the tensile strength and elongation at break of the polymer composite films, as compared to the singly modified silica. The more improved tensile properties were attributed to the more increased number of covalent links between the modified silica surface and polyurethane chains, and the better dispersion of the silica particles in the polyurethane matrix.