Superomniphobic Surfaces with Improved Mechanical Durability: Synergy of Hierarchical Texture and Mechanical Interlocking

Abstract

Due to their unique functionality, superomniphobic surfaces that display extreme repellency toward virtually any liquid, have a wide range of potential applications. However, to date, the mechanical durability of superomniphobic surfaces remains a major obstacle that prevents their practical deployment. In this work, a two-layer design strategy was developed to fabricate superomniphobic surfaces with improved durability via synergistic effect of interconnected hierarchical porous texture and micro/nano-mechanical interlocking. The improved mechanical robustness of these surfaces was assessed through water shear test, ultrasonic washing test, blade scratching test, and Taber abrasion test.

Keywords: Taber abrasion; hierarchical structure; mechanical interlocking; mechanical robustness; superomniphobic.

Figure 1.

(a) Schematic illustrating the fabrication of robust superomniphobic surface and scanning electron microscope (SEM) image showing a representative fumed silica agglomerate consisting of interconnected nano-sized silica particles. (b) and (c) Apparent contact angles and roll off angles, respectively, of water and n-hexadecane droplets (~8 μl) on the surfaces fabricated with adhesive layer of different thickness. SEM images showing the morphology of surfaces fabricated with adhesive layer of (d) 0 μm, (e) 27 μm, and (f) 78 μm. Jets of (g) water and (h) n-hexadecane bouncing on the robust superomniphobic surfaces.

Figure 2.

(a) and (b) Apparent contact angles and roll off angles, respectively, of water and n-hexadecane droplets (~8 μl) on the superomniphobic surface subjected to water shear tests. (c) and (d) Apparent contact angles and roll off angles, respectively, of water and n-hexadecane droplets (~8 μl) on the superomniphobic surface subjected to ultrasonic washing tests. Droplets of (e) water and (f) n-hexadecane bouncing on the superomniphobic surface after ultrasonic washing test.

Figure 3.

(a) and (b) Apparent contact angles and roll off angles, respectively, of water and n-hexadecane droplets (~8 μl) on the superomniphobic surface after linear Taber abrasion tests. SEM images showing the morphology of (c) as-prepared superomniphobic surface, (d) after 200 abrasion cycles, and (e) after 500 abrasion cycles.