A robust and versatile superhydrophobic coating: Wear-resistance study upon sandpaper abrasion

The mechanical durability, especially wear-resistance seriously restricts the practical application of superhydrophobic surfaces. Lots of efforts have been put to improve the mechanical durability of superhydrophobic surfaces. However, due to the lack of a standard evaluation criterion, it is inaccurate to evaluate the mechanical durability of superhydrophobic surfaces by merely comparing the abrasion cycles or distance it can stand before losing superhydrophobicity. In this paper, the wear-resistance of superhydrophobic surfaces against sandpaper abrasion was evaluated based on a typical resin-hydrophobic filler formula. The mechanical strength, coefficient of friction and evolution of superhydrophobicity with growing abrasion cycles of as-prepared superhydrophobic surfaces were carefully studied by considering the hydrophobic filler sizes. In spite that superhydrophobic surfaces can all be achieved with hydrophobic fillers from nano-meter scale particles to micro-meter scale clusters at a certain content, the larger the filler size, the better the wear-resistance. For superhydrophobic coatings with a given surface roughness, its superhydrophobicity can be preserved when abraded against items which were rougher than coating itself. Furthermore, drag reduction performance of the developed superhydrophobic surfaces was evaluated against the polymer solution. This work will provide useful clues for establishing the standard to evaluate the wear-resistance of superhydrophobic coatings.