The novel preparation of waterborne acrylic polyurethane-silica organic-inorganic interpenetrating network coatings

In this paper, a waterborne acrylic polyurethane-silica organic-inorganic interpenetrating network (IPN-WAPU-nSiO2) coating was prepared using filling hydroxyethylation modified nano-silica with 10 nm diameter (HEM-nSiO2) into waterborne acrylic polyurethane paint. Fourier transform infrared spectroscopy (FT-IR) confirms that HEM-nSiO2 can react with isocyanate to form amino ester bonds, which enhances the compatibility with acrylic polyurethane matrix and the microstructural morphology demonstrates that nano sized silicon are completely integrated into the IPN-WAPU-nSiO2 coating, which forms a significant difference from the composite waterborne acrylic polyurethane-silica (c-WAPU/nSiO2) coating prepared from filling 10 nm diameter of silica. The resulting IPN-WAPU-HEM-nSiO2 coating filling 0.1 wt% of HEM-nSiO2 has outstanding wear resistance, toughness and excellent resistance to salt spray for over 360 h with 15 μm thickness. Tafel curve and electrochemical impedance spectroscopy (EIS) reveal the outstanding corrosion protection: the |Z|0.01Hz of IPN-WAPU-HEM-nSiO2 (3wt‰) coating remains 4.61 × 109 Ω·cm2 after soaking in 3.5 wt% NaCl solution in 60 °C for 60 days, which is caused by the very dense coating with unique organic-inorganic IPN structure.