Grafting photosensitive polyurethane onto colloidal silica for use in UV-curing polyurethane nanocomposites

The colloidal silica was modified with 3-aminopropyltrimethoxysilane (APTES), and then further treated with NCO-terminated poly (ethylene glycol) methacrylate based oligomer to yield a photosensitive polyurethane modified silica (PU-silica). IR and TGA results confirmed the existence of grafted PU chains at the surface of silica. In compared to silica modified with the silane coupling agents (APTES, MEMO), the grafted PU chains enhanced interfacial interaction and compatibility between silica and polyurethane acrylate (PUA) matrix, which was further proved by rheological behavior and DMA analysis. The SEM showed that small PU-silica clusters were homogeneously dispersed in PUA matrix. The PU-silica nanoparticles functioned effectively as a multifunctional cross-linker as well as a reinforcing filler and significantly enhanced the Youngʹs modulus, tensile strength, and thermal stability of PUA nanocomposites.