Transparent non-fluorinated superhydrophobic coating with enhanced anti-icing performance

A major challenge of non-fluorinated superhydrophobic coatings is the low robustness of the infused nanoparticles in coating films compromising their non-wetting properties. In this paper we developed a robust transparent superhydrophobic coating using an alkoxysilane binder, fumed silica nanoparticles, and methyltriethoxysilane (MTES), in which MTES can act as a coupling agent between the nanoparticles and the binder to increase the stability of the hierarchical structures. The surface wettability was assessed in terms of contact angle (CA) and contact angle hysteresis (CAH) of water at different subfreezing temperatures. The spray-coated superhydrophobic coating with water CA of 163° showed appropriate adhesion to different substrates, optical transmittance of 80% in the visible-light region, and great non-wetting properties even after various extreme treatments, i.e., waterjet impacting, immersing in pollutants and acid/base solutions for 24 h, tape peeling test, and sandpaper abrasion. Self-cleaning tests demonstrated that the superhydrophobic surface could shed various contaminants in both wet and dry conditions leaving a clear surface behind. Ice-adhesion strength and delay of freezing were studied, and it was found that this superhydrophobic coating displayed excellent durability in icephobic properties. The push-off ice adhesion strength of 13.3 kPa on the superhydrophobic coating after 15 icing/de-icing cycles increased only 15% reaching to 15.4 kPa, confirming the superior icephobic behavior of the coating.