Bioinspired nanoscale hierarchical pillars for extreme superhydrophobicity and wide angular transmittance

Abstract

Hierarchical structures in nature provide unique functions for living organisms that can inspire technology. Nanoscale hierarchical structured surfaces are essential to realize the dual functions of non-wetting and transparency for...

Micro‐/Nanohierarchical Structures Physically Engineered on Surfaces: Analysis and Perspective

“…In view of their propensity to air gap formation, nanohood arrays can be used to generate Cassie-Baxter states. [1][2][3][4] In the field of dry/wet adhesives, the hierarchical structures constructed by combining two different shapes (e.g., engineered surface profiles) are primarily required for adhesion under various dry and wet conditions. For instance, in a gecko-inspired adhesive, the microtip-on-micropillar arrays help to increase van der Waals interactions associated with large specific surface area, the number of hairs (i.e., contact splitting principle), [55] and achieve the effective compliance of the hierarchical structure.…”

“…A microscale structural parameter study was reported to improve hydrophobicity by controlling the height, width, and distance between the structures. [150] The studies in the previous decades developed only superhydrophobic (water-repellent) surfaces [2,51,59,66,145,146] with contact angles of >150°and sliding angles of <10°. For example, Kim et al [151] recently reported on a superhydrophobic surface with hierarchical structures fabricated by thermal imprinting and spraying.…”

“…The fabrication of functional surfaces based on hierarchical structures is made by the combination of the vari-ous (micro, [4,6,[136][137][138] nano, [1][2][3][4]6,137,138] wrinkle, [5,6,51,62,88] and fiber [3,139,140] ) structures introduced above. For functional surface fabrication, the structures used to design the Cassie-Baxter state mostly consist of rationally designed micropatterns and ordered nanopatterns (such as fibers, dots, and pillars).…”

“…Micro-/nanohierarchical structures physically engineered on surfaces have received significant attention and are in high demand owing to their utility in applications including contact angle manipulation, [1][2][3][4][5][6] bioinspired adhesives, energy conversion/storage/harvesting devices, [28][29][30] and physical/chemical/biological sensors. [31][32][33][34][35][36][37] In addition, hierarchical structures have unique physicochemical properties DOI: 10.1002/adma.202300871 originating from synergistic effects of constituent micro-/nanostructures.…”