Poly(caprolactone)/silica organic-inorganic hybrids as protective coatings for poly(methyl methacrylate) substrates

Organic-inorganic hybrid materials (also known as ceramers or phase-interconnected nanocomposites) were prepared starting with tetraethoxysilane and alpha,omega-triethoxysilane-terminated poly(epsilon-caprolactone) (PCL-Si) using the sol-gel process, In all cases the formation of nanocomposites with a high level of interpenetration between PCL and SiO2 phases was noted. Poly(methyl methacrylate) (PMMA) slabs were dip-coated with PCL-Si/silica hybrids and a preferential segregation of silica on to the outer surface was found, together with a PCL-rich coating PMMA interface, In all cases, a marked reduction in both the average roughness and the apparent friction coefficient was noted with respect to the uncoated PMMA. All the PCL-Si/SiO2-coated samples showed a significant increase in flame resistance before and after UV irradiation, while improvements in the anti-scratch properties were noted only in the case of the PMMA coated with silica-rich ceramers.