Extreme Wetting-Resistant Multiscale Nano-/Microstructured Surfaces for Viscoelastic Liquid Repellence

Abstract

We demonstrate exceptional wetting-resistant surfaces capable of repelling low surface tension, non-Newtonian, and highly viscoelastic liquids. Theoretical analysis and experimental result confirm that a higher level of multiscale roughness topography composed of at least three structural length scales, ranging from nanometer to supermicron sizes, is crucial for the reduction of liquid-solid adhesion hysteresis. With Cassie-Baxter nonwetting state satisfied at all roughness length scales, the surface has been proven to effectively repel even highly adhesive liquid. Practically, this high-level hierarchical structure can be achieved through fractal-like structures of silica aggregates induced by siloxane oligomer interparticle bridges. The induced aggregation and surface functionalization of the silica particles can be performed simultaneously within a single reaction step, by utilizing trifunctional fluoroalkylsilane precursors that largely form a disordered fluoroalkylsiloxane grafting layer under the presence of sufficient native moisture preadsorbed at the silica surface. Spray-coating deposition of a particle surface layer on a precoated primer layer ensures facile processability and scalability of the fabrication method. The resulting low-surface-energy multiscale roughness exhibits outstanding liquid repellent properties, generating equivalent lotus effect for highly viscous and adhesive natural latex concentrate, with apparent contact angles greater than 160°, and very small roll-off angles of less than 3°.

Self-Stratifying Particulate Coating for Robust Superhydrophobic and Latex-Repellent Surface

“…Furthermore, surface roughness in multiple length scale has been proven as the key to achieve more stable Cassie-Baxter non-wetting state (2). In our previous research, we also demonstrated that tipple-scale surface roughness, obtained from silica aggregates functionalized with fluoroalkylsilane molecules, were superior to from stable extreme anti-wetting surface that can repel water or even highly adhesive liquid like concentrated natural latex (3). As the film was mainly composed of functionalized nanoparticles, however, its poor mechanical durability remains a major drawback for real uses.…”

Biomedical Science to Tackle the COVID-19 Pandemic: Current Status and Future Perspectives

“…The reduction of the coronavirus persistence on PPE surfaces can be accomplished by preventing the adhesion of the respiratory droplets onto the material surfaces [ 100 , 101 ]. To this end, metal oxides have been employed on different types of surfaces to induce biocidal effects over pathogens, as it is discussed below [ 65 , 66 , 67 , 69 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 ].…”

“…Another proposed strategy to improve the protective equipment and increase safety among wearers is the use of tailored nanomaterials to minimize the wettability of hydrophilic droplets by using an NP-based coating [ 101 , 120 , 121 ]. In this regard, nanofibers from different nanocomposites, such as eggshell membrane and silk fibroin nanofibers, have been evaluated, by taking advantage of their hydrophobicity and biocompatibility, to reduce the wettability in biomedical applications, such as face masks [ 111 ].…”

A Study on Insulation Characteristics of Glass Wool and Mineral Wool Coated with a Polysiloxane Agent

“…The moistureresistant liquid in this study used nanosilicate which is manufactured in-house and fluoroalkylsiloxane compound and its preparation process is as follows [16].…”