Anti-corrosion non-isocyanate polyurethane polysiloxane organic/inorganic hybrid coatings

Abstract

As people become more aware of the necessity and importance of environment protection and product safety, the environmentally friendly non-isocyanate polyurethane (NIPU) has received great attention. In this work, a series of NIPU anti-corrosion coatings were prepared by amine-terminated NIPU, tetraethyl orthosilicate (TEOS), and bisphenol A (BPA) epoxy. First, the BPA cyclic carbonate was synthesized from carbon dioxide and BPA epoxy resin. Then, the amine-terminated NIPU was synthesized from BPA cyclic carbonate and fatty acid amine. Next, the NIPU TEOS hybrid coatings were formulated by different amounts of TEOS. The anti-corrosion performance of NIPU TEOS hybrid coatings was evaluated by electrochemical impedance spectroscopy and salt spray. NIPU coating with 5 wt. % of TEOS showed the best anti-corrosion behavior while NIPU coating with 20 wt. % of TEOS exhibited the worst corrosion resistance. The resulting anti-corrosion difference was attributed to the organic/inorganic micro-phase separation, which was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. This study reveals the effect of TEOS on the anti-corrosion performance of environmentally friendly NIPU coatings.