Diving beetle-inspired durable omniphobic slippery coatings with pit-type non-smooth topography

The development of bio-inspired anti-wetting surfaces by mimicking the surface morphology and chemistry of naturally occurring species has attracted widespread researcher attention. However, the unstable topography and chemistry of these surfaces seriously affect their durability, and the unilateral improvement strategy to render robust topography or chemistry limits the liquid repellent properties. In this study, a diving beetle-inspired omniphobic slippery coating with a low-surface-energy chemistry and pit-type non-smooth topography was fabricated by a facile spraying approach. As the pivotal building units, eco-friendly monoglycidyl ether-terminated polydimethylsiloxane was selected for grafting onto a crosslinked network, affording a dense brush layer and micron-sized pits with a low depth-to-diameter ratio via self-stratification and phase separation, respectively. The pit-type non-smooth structure of the prepared coating surface enabled the sliding resistance reduction for droplets via triggering secondary vortices, resulting in the facile sliding of the test liquids including ultra-small droplets (1 μL) at low tilted angles. Furthermore, the resultant coating exhibited outstanding self-cleaning, anti-fouling, and anti-marking properties. These properties were still retained after the coatings were immersed in harsh liquid environments for a long time or suffered high-intensity abrasion. This bio-inspired strategy provides a pioneering method for developing robust and durable omniphobic slippery coatings with a low sliding resistance.