Surface mechanical properties of poly(urethane acrylate)/silica hybrid interpenetrating polymer network (IPN) coatings

Surface mechanical properties of poly(urethane acrylate) (PUA)/silica hybrid interpenetrating polymer network (IPN) coating materials were investigated using several test methods including nano-indentation, nano-scratch, pencil hardness, and stretching. To prepare coated films, an organic part (urethane acrylate) was mixed with an inorganic part (silica) at various ratios. Independent crosslinking reactions were applied to form the hybrid IPN structure: UV curing and sol-gel reactions were used for the organic and inorganic parts, respectively. The prepared hybrid IPN coatings exhibited no macroscopic phase separation. As the silica content was increased, the values for indentation hardness and pencil hardness increased, while failure strain during stretching test decreased. It was found that the hybrid IPN coating with its balanced dissipative and elastic properties had better scratch resistance than that of other coatings.