An Omniphobic Spray Coating Created from Hierarchical Structures Prevents the Contamination of High-Touch Surfaces with Pathogens.

Engineered surfaces that repel pathogens are of great interest due to their role in mitigating the spread of infectious diseases. A robust, universal, and scalable omniphobic spray coating with excellent repellency against water, oil, and pathogens is presented. The coating is substrate-independent and relies on hierarchically structured polydimethylsiloxane (PDMS) microparticles, decorated with gold nanoparticles (AuNPs). Wettability studies reveal the relationship between surface texturing of micro- and/or nano-hierarchical structures and the omniphobicity of the coating. Studies of pathogen transfer with bacteria and viruses reveal that an uncoated contaminated glove transfers pathogens to >50 subsequent surfaces, while a coated glove picks up 104 (over 99.99%) less pathogens upon first contact and transfers zero pathogens after the second touch. The developed coating also provides excellent stability under harsh conditions. The remarkable anti-pathogen properties of this surface combined with its ease of implementation, substantiate its use for the prevention of surface-mediated transmission of pathogens.

Rapid and Robust Surface Treatment for Simultaneous Solid and Liquid Repellency.

A wide range of liquid and solid contaminants can adhere to everyday functional surfaces and dramatically alter their performance. Numerous surface modification strategies have been developed that can reduce the fouling of some solids or repel certain liquids but are generally limited to specific contaminants or class of foulants. This is due to the typically distinct mechanisms that are employed to repel liquids vs solids. Here, we demonstrate a rapid and facile surface modification technique that yields a thin film of linear chain siloxane molecules covalently tethered to a surface. We investigate and characterize the liquid-like morphology of these surfaces in detail as the key contributing factor to their anti-fouling performance. This surface treatment is extremely durable and readily repels a broad range of liquids with varying surface tensions and polarities, including water, oils, organic solvents, and even fluorinated solvents. Additionally, the flexible, liquid-like nature of these surfaces enables interfacial slippage, which dramatically reduces adhesion to various types of solids, including ice, wax, calcined gypsum, and cyanoacrylate adhesives, and also minimizes the nucleation of inorganic scale. The developed surfaces are durable and simple to fabricate, and they minimize fouling by both liquids and solids simultaneously.

Silicone Brushes: Omniphobic Surfaces with Low Sliding Angles.

Losing contact: Omniphobic surfaces can be readily produced by acid-catalyzed graft polycondensation of dimethyldimethoxysilane (PDMS). Droplets show a very small contact angle hysteresis as well as a low sliding angle of only a few degrees. The nm-thick PDMS layer is neither easily washed away nor depleted. This method offers a novel approach towards the preparation of super-liquid-repelling surfaces.

Covalently Attached Liquids: Instant Omniphobic Surfaces with Unprecedented Repellency.

Recent strategies to prepare "omniphobic" surfaces have demonstrated that minimizing contact angle hysteresis (CAH) is the key criterion for effectiveness. CAH is affected by chemistry and topography defects at the molecular and higher levels, thus most surfaces exhibit significant CAH. Preparative methods for stable coatings on smooth substrates with negligible CAH (<2°) for a broad range of liquids have not been reported. In this work, we describe a simple and rapid procedure to prepare omniphobic surfaces that are stable under pressure and durable at elevated temperatures. Consistent with theory, they exhibit sliding angles that decrease with liquid surface tension. Slippery omniphobic covalently attached liquid (SOCAL) surfaces are obtained through acid-catalyzed graft polycondensation of dimethyldimethoxysilane. The smooth, stable, and temperature-resistant coatings show extremely low CAH (≤1°) and low sliding angles for liquids that span surface tensions from 78.2 to 18.4 mN m(-1).

"Insensitive" to touch: fabric-supported lubricant-swollen polymeric films for omniphobic personal protective gear.

The use of personal protective gear made from omniphobic materials that easily shed drops of all sizes could provide enhanced protection from direct exposure to most liquid-phase biological and chemical hazards and facilitate the postexposure decontamination of the gear. In recent literature, lubricated nanostructured fabrics are seen as attractive candidates for personal protective gear due to their omniphobic and self-healing characteristics. However, the ability of these lubricated fabrics to shed low surface tension liquids after physical contact with other objects in the surrounding, which is critical in demanding healthcare and military field operations, has not been investigated. In this work, we investigate the depletion of oil from lubricated fabrics in contact with highly absorbing porous media and the resulting changes in the wetting characteristics of the fabrics by representative low and high surface tension liquids. In particular, we quantify the loss of the lubricant and the dynamic contact angles of water and ethanol on lubricated fabrics upon repeated pressurized contact with highly absorbent cellulose-fiber wipes at different time intervals. We demonstrate that, in contrast to hydrophobic nanoparticle coated microfibers, fabrics encapsulated within a polymer that swells with the lubricant retain the majority of the oil and are capable of repelling high as well as low surface tension liquids even upon multiple contacts with the highly absorbing wipes. The fabric supported lubricant-swollen polymeric films introduced here, therefore, could provide durable and easy to decontaminate protection against hazardous biological and chemical liquids.