UV-curable hybrid coatings based on vinylfunctionlized siloxane oligorner and acrylated polyester

Organic-inorganic hybrid coatings were formulated using multifunctional vinyltrimethoxysilane (VTMS) oligomers and acrylated polyester (AP). A radical photoinitiator was added to the VTMS/AP formulation and the films were crosslinked via UV-radiation. The viscoelastic, thermomechanical, and surface properties of the VTMS/AP films were evaluated as a function of VTMS content, using dynamic mechanical thermal analysis (DMTA), thermal gravimetric analysis (TGA), contact angle, fracture toughness, and tensile properties. In addition, coating properties such as adhesion, scratch resistance, pencil hardness, and impact resistance were also investigated. The tensile and scratch data show that VTMS oligomer dramatically increased hardness and scratch resistance. The VTMS oligomer also increased the contact angle, led to a decrease in surface tension, and improved surface appearance. The VTMS oligomer also increases storage modulus, glass transition temperature, and crosslink density. The morphology of films and the particle size were observed using atomic force microscopy (AIM). The data indicated that the average silica particle size was -90 nm and the particles were well-dispersed in the organic phase. It was postulated that the VTMS oligomer functioned effectively as a hyperbranched crosslinker, surface modifier, and reactive diluent. (c) 2007 Wiley Periodicals, Inc.