Biomimetic Coating-free Superomniphobicity (Scientific Reports)

by Das, R., Ahmad, Z., Nauruzbayeva, J., & Mishra, H.*.
Year: 2020

Bibliography

Das, R., Ahmad, Z., Nauruzbayeva, J., & Mishra, H. Biomimetic Coating-free Superomniphobicity. Sci Rep 10, 7934 (2020). https://doi.org/10.1038/s41598-020-64345-1

Extra Information

This article was featured in KAUST Discovery

Abstract

Superomniphobic surfaces, which repel droplets of water and organics, are used for water-proofing, drag reduction, and separation processes. These surfaces exploit perfluorocarbons, which are expensive and fragile. Thus, new approaches for achieving superomniphobicity from common materials are desirable. In this context, microtextures comprising “mushroom-shaped” doubly reentrant pillars (DRPs) have been shown to repel drops of polar and apolar liquids in air irrespective of the surface make-up. However, it was recently demonstrated that DRPs get instantaneously infiltrated by the same liquids on submersion because while they can robustly prevent liquid imbibition from the top, they are vulnerable to lateral imbibition. Here, we remedy this weakness through bio-inspiration derived from cuticles of Dicyrtomina ornata, soil-dwelling bugs, comprising cuboidal granules with mushroom-shaped features on each face. Towards a proof-of-concept demonstration, we created a perimeter of biomimicking pillars around arrays of DRPs using a two-photon polymerization technique; other variations of this design were also tested. The resulting gas-entrapping microtextured surfaces (GEMS) robustly entrap air on submersion in wetting liquids, while also exhibiting superomniphobicity in air. To our knowledge, this is the first-ever microtexture that confers upon intrinsically wetting materials the ability to simultaneously exhibit superomniphobicity in air and robust  entrapment of air on submersion. These findings should advance the rational design of coating-free liquid-repellent technologies.

Keywords

Biomimetics Mushroom-shaped pillars doubly reentrant pillars Gas-entrapping microtextured surfaces Superomniphobicity Superhydrophobicity Superoleophobicity Two-photon polymerization Additive manufacturing Contact angle hysteresis