pH-responsive corrosion protection coating with chitosan encapsulated halloysite nanotubes for active protection of copper

Alkaline-etched halloysite nanotubes (HNTs) loaded the corrosion inhibitor 5-ethyl-1,3,4-thiadiazol-2-amine (ETDA), and encapsulated with chitosan (CS), was prepared as a novel nanofiller. Nanofillers were incorporated into the coating to prepare an anticorrosion coating with good dispersion and pH responsiveness. The mass of HNTs loaded ETDA and encapsulated CS were approximately 11 wt% and 41 wt%. CS-HNTs-ETDA nanoparticles exhibited good dispersion in Epoxide resin (EP). A better active protection was obtained after the scratched coating immersion in 3.5 wt% NaCl solution for 30 d. The active protection rate of coating with CS-HNTs-ETDA is better than that of coating with HNTs-ETDA at pH = 3, 7 and 9, and the best at pH = 3. ETDA was released from the uniformly dispersed CS-HNTs-ETDA in the coating and adsorbed on the copper surface at the scratch, formed a tight and thin film that isolated corrosive substances. This enables the coating to actively protect damaged areas and extending the equipment's lifespan. [Display omitted] •An active protection coating with pH-responsive function was designed.•CS improved the dispersion of CS-HNTs-ETDA in epoxy resins.•CS and ETDA have positive effects on anticorrosion of copper coating in pH