Superhydrophobic imidazole encapsulated hollow zinc phosphate nanoparticles were synthesized and used in an epoxy coating as a corrosion inhibitor for protecting the mild steel. The surfactant assisted facile sonochemical route has been used for the synthesis of hollow zinc phosphate nanoparticles. The nanoparticles were characterized by X-ray diffraction, Brunnauer–Emmett–Teller nitrogen adsorption/desorption isotherms, field emission scanning electron microscopy and transmission electron microscopy analysis to confirm the successive formation of a hollow assembly of the zinc phosphate. The encapsulation and the release (under acidic and basic pH conditions) of imidazole from the hollow lumen of the zinc phosphate were determined by UV–vis spectrophotometric analysis. The surface of the imidazole encapsulated hollow zinc phosphate nanoparticle was successfully grafted with octanol to achieve superhydrophobicity. The contact angle of the octanol-grafted nanoparticles was found to be 154° as their surface was modified by −(CH2)6CH3 groups. The anticorrosive performance of the prepared epoxy material has been checked by incorporating it into the epoxy resin and were coated over the mild steel panels. The results have been compared with the neat epoxy and normal zinc phosphate incorporated epoxy coatings for their corrosion inhibition performance. The electrochemical impedance spectroscopy and salt spray analysis have been used to evaluate the anticorrosion performance of all the three coatings. The anticorrosive performance of the epoxy coating incorporated with superhydrophobic imidazole loaded hollow zinc phosphate was found to be far superior compared to the neat epoxy and normal zinc phosphate incorporated epoxy coating.
Volume 114, January 2018, Pages 33–39