Acrylic-based polyurethane/silica hybrids prepared by acid-catalyzed sol-gel process: Structure and mechanical properties

Silica sols were first prepared based on different ratios of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) by an acid-catalyzed sol-gel process, and then incorporated into acrylic-based polyurethanes. The structures and morphologies of silicone-oxo clusters were studied by Si-29 NMR, SAXS, and scanning electron microscopy (SEM), whereas the mechanical properties of polyurethane/silica hybrids were characterized by DMA and tensile tests. The silicone-oxo clusters in both silica sol and polyurethane hybrids became denser and larger at a higher molar ratio of TEOS/MTES and higher silica content, and the silica-oxo clusters of polyurethane/silica hybrids even became more compact and larger than those of silica sols, increasing the elastic modulus and tensile strength of polyurethane/silica hybrids.