Editing Biomimetics (section)

=== Liquid repellency ===
Superliquiphobicity refers to a remarkable surface property where a solid surface exhibits an extreme aversion to liquids, causing droplets to bead up and roll off almost instantaneously upon contact. This behavior arises from intricate surface textures and interactions at the nanoscale, effectively preventing liquids from wetting or adhering to the surface. The term "superliquiphobic" is derived from "[[Ultrahydrophobicity|superhydrophobic]]," which describes surfaces highly resistant to water. Superliquiphobic surfaces go beyond water repellency and display repellent characteristics towards a wide range of liquids, including those with very low surface tension or containing surfactants.<ref name=":6">{{Cite journal |title=Biomimetics |url=http://www.springer.com/us/book/9783319716756 |journal=SpringerLink |language=en}}</ref><ref>{{Cite journal |last1=Tuteja |first1=Anish |last2=Choi |first2=Wonjae |last3=Ma |first3=Minglin |last4=Mabry |first4=Joseph M. |last5=Mazzella |first5=Sarah A. |last6=Rutledge |first6=Gregory C. |last7=McKinley |first7=Gareth H. |last8=Cohen |first8=Robert E. |date=2007-12-07 |title=Designing Superoleophobic Surfaces |url=https://www.science.org/doi/10.1126/science.1148326 |journal=Science |language=en |volume=318 |issue=5856 |pages=1618–1622 |doi=10.1126/science.1148326 |pmid=18063796 |bibcode=2007Sci...318.1618T |s2cid=36967067 |issn=0036-8075}}</ref>

Superliquiphobicity emerges when a solid surface possesses minute roughness, forming interfaces with droplets through wetting while altering contact angles. This behavior hinges on the roughness factor (R<sub>f</sub>), defining the ratio of solid-liquid area to its projection, influencing contact angles. On rough surfaces, non-wetting liquids give rise to composite solid-liquid-air interfaces, their contact angles determined by the distribution of wet and air-pocket areas. The achievement of superliquiphobicity involves increasing the fractional flat geometrical area (f<sub>LA</sub>) and R<sub>f</sub>, leading to surfaces that actively repel liquids.<ref>{{Cite journal |last=Wenzel |first=Robert N. |title=Resistance of Solid Surfaces to Wetting by Water |date=August 1936 |url=https://pubs.acs.org/doi/abs/10.1021/ie50320a024 |journal=Industrial & Engineering Chemistry |language=en |volume=28 |issue=8 |pages=988–994 |doi=10.1021/ie50320a024 |issn=0019-7866}}</ref><ref>{{Cite journal |last1=Cassie |first1=A. B. D. |last2=Baxter |first2=S. |date=1944 |title=Wettability of porous surfaces |url=http://xlink.rsc.org/?DOI=tf9444000546 |journal=Transactions of the Faraday Society |language=en |volume=40 |pages=546 |doi=10.1039/tf9444000546 |issn=0014-7672}}</ref>

The inspiration for crafting such surfaces draws from nature's ingenuity, illustrated by the "[[lotus effect]]". Leaves of water-repellent plants, like the lotus, exhibit inherent hierarchical structures featuring nanoscale wax-coated formations.<ref>{{Cite journal |last=Neinhuis |first=C |date=June 1997 |title=Characterization and Distribution of Water-repellent, Self-cleaning Plant Surfaces |journal=Annals of Botany |volume=79 |issue=6 |pages=667–677 |doi=10.1006/anbo.1997.0400|doi-access=free |bibcode=1997AnBot..79..667N }}</ref><ref>{{Cite journal |last1=Barthlott |first1=W. |last2=Neinhuis |first2=C. |date=1997-04-30 |title=Purity of the sacred lotus, or escape from contamination in biological surfaces |url=http://link.springer.com/10.1007/s004250050096 |journal=Planta |volume=202 |issue=1 |pages=1–8 |doi=10.1007/s004250050096 |bibcode=1997Plant.202....1B |s2cid=37872229 |issn=0032-0935}}</ref> Other natural surfaces with these capabilities can include Beetle carapaces,<ref name="m004">{{cite journal | last=Zhu | first=Hai | last2=Guo | first2=Zhiguang | title=Hybrid engineered materials with high water-collecting efficiency inspired by Namib Desert beetles | journal=Chemical Communications | volume=52 | issue=41 | date=2016 | issn=1359-7345 | doi=10.1039/C6CC01894G | pages=6809–6812}}</ref> and cacti spines,<ref name="bumpyAWH">{{cite journal | last=Zarei | first=Mojtaba | last2=Dabir | first2=Bahram | last3=Esmaeilian | first3=Nima | last4=Warsinger | first4=David M. | title=Biomimetic bumpy and eco-friendly slippery surfaces for enhanced dew and fog water harvesting | journal=Journal of Water Process Engineering | volume=70 | date=2025 | doi=10.1016/j.jwpe.2025.106950 | page=106950}}</ref> which may exhibit rough features at multiple size scales. These structures lead to superhydrophobicity, where water droplets perch on trapped air bubbles, resulting in high contact angles and minimal contact angle hysteresis. This natural example guides the development of superliquiphobic surfaces, capitalizing on re-entrant geometries that can repel low surface tension liquids and achieve near-zero contact angles.<ref>{{Cite journal |last1=Tuteja |first1=Anish |last2=Choi |first2=Wonjae |last3=McKinley |first3=Gareth H. |last4=Cohen |first4=Robert E. |last5=Rubner |first5=Michael F. |date=August 2008 |title=Design Parameters for Superhydrophobicity and Superoleophobicity |url=http://link.springer.com/10.1557/mrs2008.161 |journal=MRS Bulletin |language=en |volume=33 |issue=8 |pages=752–758 |doi=10.1557/mrs2008.161 |s2cid=138093919 |issn=0883-7694}}</ref>

Creating superliquiphobic surfaces involves pairing re-entrant geometries with low surface energy materials, such as fluorinated substances or liquid-like silocones.<ref name="bumpyAWH"/> These geometries include overhangs that widen beneath the surface, enabling repellency even for minimal contact angles. These surfaces find utility in self-cleaning, anti-icing, anti-fogging, antifouling, enhanced condensation,<ref name="bumpyAWH"/> and more, presenting innovative solutions to challenges in biomedicine, desalination, atmospheric water harvesting, and energy conversion.

In essence, superliquiphobicity, inspired by natural models like the lotus leaf, capitalizes on re-entrant geometries and surface properties to create interfaces that actively repel liquids. These surfaces hold immense promise across a range of applications, promising enhanced functionality and performance in various technological and industrial contexts.