Competitive Wetting: A New Approach to Prevent Liquid Penetration through Porous Materials with Superior Synergistic Effect

Abstract

Protective clothing is designed to isolate people from hazardous toxic chemicals and chemical warfare agents Impermeable and semipermeable materials provide superior barriers against penetration of chemical agents in the forms of liquid, vapor, and aerosol, but are apt to cause severe heat stress consequences for the users. Permeable protective clothing is highly preferred because of its high breathability characteristic. [1] It generally has a multilayer fabric structure consisting of an outer liquid-repellent layer with superhydrophobicity and/ or superoleophobicity properties, [2][3][4][5][6][7][8][9][10] a middle absorptive layer functioning to adsorb toxic chemical vapor, aerosols, and a small amount of liquid, [11][12][13] and an inner layer that helps absorb perspiration and improves wearer comfort. [14] The current permeable protective clothing, however, usually meet difficulties in repelling toxic industrial chemical (TIC) and chemical warfare agent (CWA) liquids of low surface tension, failing protection. [15] Considerable efforts have been devoted to improving the liquid repellency of protective clothing. [16] The conventional approach is to increase the superoleophobicity of the surface layer using coating materials comprised of fluorine-containing chemicals and nanomaterials. [17,18] Despite the significant progress in preventing liquids penetration by surface coating, [18][19][20][21][22][23] some have claimed that the coating is, in fact, super-repellent to ultralow surface tension liquids, [4,7,18] however, no surface was able to Blocking liquid penetration in porous materials is a key function for several applications including chemical protective clothing (CPC), wound healing, and hygiene products. Enormous efforts are made to prevent liquid penetration through porous media by the modification of materials. CPC is used as an example to demonstrate the effect of the synergistic effect on liquid penetration. A common strategy to achieve liquid protection is the use of liquidrepellent surfaces with the aid of a liquid absorption liner layer. However, this strategy demonstrates limited success for low surface energy liquids. Herein, a novel approach is reported to prevent the permeation of liquid across porous materials by a synergistic effect. Both fabrics are individually susceptible to be wetted by low surface tension liquids. However, when they are assembled, they can prevent low surface tension liquids from penetrating because of the wettability gap between the two fabrics. The fabric assembly demonstrates an increase in the liquid prevention capacity by 70-1000 times compared with a commercial CPC material. This novel synergistic effect may offer a breakthrough in the development of various applications including protective clothing baby nappies, hygiene products, food preparation, soil water retention, and sporting/camping/ski equipment and clothing.

Recent Advances in Superhydrophobic Materials Development for Maritime Applications

“…This shift from mono micro/nano patterns to intricate hierarchical nano‐micron scale structures and multifunctionalities reflects the field's ongoing pursuit of remarkable advancements in SH surfaces. There have been several notable reviews in the area of SH materials that have focused on important topics of interest, including the development of coating technologies that are environmentally friendly and sustainable, [ 42 ] and that use sustainable colloidal materials in their production, [ 43 ] long term coating robustness and performance, [ 44 ] mechanical durability, [ 45 , 46 ] and progress on submersible SH materials, including the maintenance of the surface plastron. [ 22 , 38 ] These reviews collectively highlight the significance of bioinspired concepts, micro/nano structure modifications, and chemical compositions in engineered SH surfaces and their applications.…”