Reducing the water absorption in epoxy coatings by silane monomer incorporation

In this communication, 3-glycidoxypropyltrimethoxy silane (GPTMS) was used as an additive to inhibit the water absorption of epoxy coatings. Coating capacitance, which was measured by electrochemical impedance spectroscopy (EIS), was employed to calculate the amount of water uptake in epoxy coatings in aqueous solution. The water absorption in epoxy coatings was found to decrease drastically after incorporated with silane component. It was interestingly found that the glass-transition temperature (Tg) of silane-mixed epoxy coatings continuously increased during the immersion, extremely contrast with that of silane-free polymeric substrates, which was observed to decrease significantly after water permeation as reported in previous literatures.