Transferrable Electrospinning Nanofiber Meshes as Strongly Adhered Scaffolds for Slippery Liquid-Infused Porous Surfaces

Slippery liquid-infused porous surfaces (SLIPS) are self-healing protective coatings that can be made by infiltration of a porous scaffold with a chemically resistant oil. A popular method to apply a SLIPS coating is using electrospinning to deposit a nanofiber mesh onto the intended substrate. However, electrospinning only lightly deposits the nanofibers onto the intended substrate, so the coating detaches easily even when unintended. We report a simple, yet effective, solution to the adhesion problem. Electrospun nanofiber meshes are typically well entangled and cohesive, so they can be detached from the electrospinning target and transferred onto the final target. Using a thin layer of adhesive on the intended surface, the electrospinning mesh can be securely attached and infiltrated with protective oil to yield a more stable SLIPS coating. An adhered coating can be submerged under corrosive solution and repeatedly self-heal from damage to the same spot. With the electrospun nanofiber meshes' flexibility and stretchability, the meshes can be fitted around a wide range of targets including ones that are otherwise difficult to apply a nanofiber mesh on. The use of an adhesive interlayer between the nanofiber mesh and substrate is a simple solution to improve coating stability, and the solution facilitates application of SLIPS onto a broader range of substrates.

Liquid-like polymer-based self-cleaning coating for effective prevention of liquid foods contaminations

Liquid food containers commonly suffer from inevitable contamination and even biofilm formation due to the adhesion of food residuals or saliva, which requires detergents to clean. Although previously reported superhydrophobic and omniphobic coatings can resist the adhesion of liquids, the requirements of specific nanostructures or infused lubricants limit their applications in food containers. Here, by grafting smooth glass containers with "liquid like" polydimethylsiloxane brushes, we developed a unique approach for preparing a slippery coating that could exhibit highly robust repellency to various liquid foods. The coating was highly transparent and did not induce a significant alteration of the smooth surface. The "liquid like" coating could effectively prevent the adhesion of various liquid foods and inhibit the formation of bacterial biofilms, without the use of detergents for cleaning. Moreover, this coating could resist mechanical damage from friction, and displayed high biocompatibility with biological cells. The slipperiness, smoothness, robustness and biocompatibility of the "liquid like" coating was highly beneficial to practical applications as self-cleaning glass container, which has been challenging to achieve by conventional superhydrophobic or omniphobic coatings. Our study introduced a versatile strategy to functionalize biocompatible surfaces for food containers which reduced the contamination of residues and the use of detergents, and may be beneficial to human and environmental health.

Designing Liquid-Infused Surfaces for Medical Applications: A Review

The development of new technologies is key to the continued improvement of medicine, relying on comprehensive materials design strategies that can integrate advanced therapeutic and diagnostic functions with a variety of surface properties such as selective adhesion, dynamic responsiveness, and optical/mechanical tunability. Liquid-infused surfaces have recently come to the forefront as a unique approach to surface coatings that can resist adhesion of a wide range of contaminants on medical devices. Furthermore, these surfaces are proving highly versatile in enabling the integration of established medical surface treatments alongside the antifouling capabilities, such as drug release or biomolecule organization. Here, the range of research being conducted on liquid-infused surfaces for medical applications is presented, from an understanding of the basics behind the interactions of physiological fluids, microbes, and mammalian cells with liquid layers to current applications of these materials in point-of-care diagnostics, medical tubing, instruments, implants, and tissue engineering. Throughout this exploration, the design parameters of liquid-infused surfaces and how they can be adapted and tuned to particular applications are discussed, while identifying how the range of controllable factors offered by liquid-infused surfaces can be used to enable completely new and dynamic approaches to materials and devices for human health.

Dropwise condensation on bioinspired hydrophilic-slippery surface

To promote the water vapor condensation efficiency in the presence of a non-condensable gas, both high nucleation rate and efficient droplet departure are desired on the condensing surface. Superhydrophobic surfaces with large water contact angles ensure the dropwise condensation mode and efficient droplet departure ability. Alternatively, efficient nucleation requires the surface to be hydrophilic. To combine these two seemingly contradictory factors on a single surface, we presented a copper-based hydrophilic-slippery surface in this study by depositing a lubricant (trimethoxysilane) on the microstructured copper substrate. The water droplet had both low contact angles and sliding angles on the surface, and stable dropwise condensation could be realized with and without non-condensable gas. The present hydrophilic-slippery surface demonstrated promising potential to enhance condensation heat transfer, particularly for cases with non-condensable gas. Improved droplet mobility was observed as compared to a superhydrophobic surface, hydrophobic surface, and hydrophobic-slippery surface. The most attractive feature lies in the enhanced nucleation process due to hydrophilicity, which is more favorable as it requires small subcooling degree and large non-condensable gas content. By revealing that a sliding angle could be accompanied by a small contact angle, this hydrophilic-slippery surface could improve our understanding in designing new functional surfaces for phase change, anti-icing, self-cleaning, and anti-fouling applications.

A hydrophilic-slippery copper surface is fabricated, reconciling two required factors, enhanced condensation and efficient water transport. Nucleation rate, droplet mobility and heat transfer are enhanced by the small contact angle and sliding angle.