Enhancement of adhesion, mechanical strength and anti-corrosion by multilayer superhydrophobic coating embedded electroactive PANI/CNF nanocomposite

Traditional insulative coatings usually suffer from pitting corrosion in harsh corrosive environment. Herein, in this work, electroactive polyaniline/carboxylated carbon nanofiber (PANI/CNF) nanocomposite was prepared via in situ chemical polymerization and first incorporated into superhydrophobic coating with better barrier effect. Multilayer coatings were constructed by facial spraying using polyphenylene sulfide (PPS) and ethylene tetrafluoroethylene (ETFE) with gradient weight ratios as film-forming materials. The composite coating with 40 wt% ETFE in top layer (denoted as ETFE-40) possesses best superhydrophobicity and highest oleophobicity with water contact angle (CA) and glycerol CA of 160 degrees and 155 degrees as well as low water sliding angle (SA) and glycerol SA of 2.2 degrees and 8.8 degrees, respectively. The lotus-like nano/micro structures, low surface energy material ETFE and modification of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS) should contribute to the superior liquid repellency. Especially, robust mechanical strength and durable anti-wettability are obtained with high WCA of 151 degrees and glycerol CA of 147 degrees after 8000 cycles abrasion. The composite coating also exhibits strong adhesion and superior self-cleaning. The enhanced electrochemical corrosion resistance of the coating in 3.5 wt% NaCl solution can be attributed to the outstanding barrier function of superhydrophobic surface and the passivation effect of electroactive PANI/CNF. This novel and effective coating system would definitely benefit the development of robust protective coating and promise wider engineering application.