Benzotriazole functionalized polydimethylsiloxane for reinforcement water-repellency and corrosion resistance of bio-based waterborne epoxy coatings in salt environment

This study reported a novel bio-based waterborne epoxy (WE) coating with superior water-repellency and anti-corrosion performance by embedding polydimethylsiloxane functionalized by benzotriazole (PDMS-BTA). Based on electrochemical measurement and salt immersion test, the WE coating containing 5 wt% PDMS-BTA exhibited optimum anticorrosive performance, whose impedance modulus at 0.01 Hz was 120 times higher than that of the plain WE coating after immersion in electrolytes for 45 days, and corrosion rate was as low as 3.76 × 10−4 mpy. The superior anticorrosion property was attributed to the water-repellent property of surface-enriched PDMS and the passivation protection of BTA. [Display omitted] •Cardanol-based WCA could improve the compatibility with waterborne epoxy resin.•BTA covalently bonded with PDMS could provide effective protection.•PDMS could transform the surface of plain WE coating to be liquid-repellent.•BTA could enhance the passivation protection to metal substrate.•Bio-based WE coating could be ecological, economic and safety.