Fast preparation of mechanically stable superhydrophobic surface by UV cross-linking of coating onto oxygen-inhibited layer of substrate

To fabricate mechanically stable superhydrophobic surfaces, conventional methods often involve complicated and time-consuming processing to improve the interface adhesion between coating and substrate, such as multi-step pre-treatments of the substrate and long time post-curing for both substrate and coating. Here, we report a facile and fast method to prepare the robust and stretchable superhydrophobic surface by rapid UV cross-linking of the superhydrophobic coating (based on polydimethylsiloxane/silica composite) onto a stretchable substrate. Polyurethane acrylate (PUA) with double bonds was UV cured to form the stretchable elastomeric substrate, the surface of which remains uncured PUA due to the presence of oxygen inhibition. The oxygen-inhibited layer of the substrate can provide a lot of reactive sites for covalently bonding to the superhydrophobic coating under UV exposure and thus eliminates the requirement for complicated surface treatments of the substrate. The formed covalent cross-linking between the superhydrophobic coating and the PUA substrate facilitates their interface adhesion. As expected, the superhydrophobic coating covalently-bonded to the PUA substrate shows good superhydrophobicity and self-cleaning ability against mechanical abrasion and stretching damages. Besides, the resulting superhydrophobic surface can withstand 1000-cycle stretching-releasing (strain of 0% → 200% → 0%) without losing its original superhydrophobicity. Thus, this robust superhydrophobic surface could find a wide range of water-proof applications for flexible substrates such as stretchable electronics, functional textiles, and outdoor sport goods.