Lubricant-Infused Surfaces for Low-Surface-Tension Fluids: Promise versus Reality

Abstract

The past few decades have seen substantial effort for the design and manufacturing of hydrophobic structured surfaces for enhanced steam condensation in water-based applications. Such surfaces promote dropwise condensation and easy droplet removal. However, less priority has been given to applications utilizing low-surface-tension fluids as the condensate. Lubricant-infused surfaces (LISs) or slippery liquid-infused porous surfaces (SLIPSs) have recently been developed, where the atomically smooth, defect-free slippery surface leads to reduced pinning of water droplets and omniphobic characteristics. The remarkable results of LISs and SLIPSs with a range of working fluid droplets give hope of their viability with low-surface-tension condensates. However, the presence of the additional liquid in the form of lubricant brings other issues to consider. Here, in an effort to study the dropwise condensation potential of LISs and SLIPSs, we investigate the miscibility of a range of low-surface-tension fluids with widely used lubricants in LIS and SLIPS design. We consider a wide range of condensate surface tensions (12-73 mN/m) and different categories of lubricants with varied viscosities (5-2700 cSt), namely, fluorinated Krytox oils, hydrocarbon silicone oils, mineral oil, and ionic liquids. In addition, we use both theory and pendant drop experiments to predict the cloaking behavior of the lubricants and immiscible condensate working fluid pairs. Our work not only shows that careful attention must be paid to lubricant-condensate selection to create long-lasting LISs or SLIPSs but also develops lubricant selection design guidelines for stable LISs and SLIPSs for enhanced condensation in applications utilizing low-surface-tension working fluids.

Designing Liquid‐Infused Surfaces for Medical Applications: A Review

“…Displacement of the liquid layer can also occur when a low‐surface‐energy infusing liquid spreads over a droplet of high‐surface‐energy contaminating liquid in what is known as a “cloaking” or “wrapping” layer ( Figure A) . The loss of the infusing liquid from the surface when the droplet is shed can lead to eventual failure of the functional liquid layer.…”

“…However, not all types of infusing liquids will cloak all types of contaminating materials. Miljkovic and co‐workers examined a range of both infusing and contaminating liquids for their abilities to create cloaking layers, identifying several infusing–contaminating liquid pairs that did not form cloaks (Figure C). Liquid loss caused by cloaking layers can also be minimized by keeping liquid‐infused surfaces continuously immersed or choosing pairs that have more slowly forming cloaking layers or form only smaller wetting ridges on the timescale of flow.…”

“…C) Conditions for effective selection of lubricant in designing stable liquid‐infused surfaces. Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…Although the bulk of recent research into liquid‐infused surfaces has been focused on the general physics and application of the concept as well as resistance to low‐surface‐tension liquids, ice, and industrial foulants, the use of these surfaces in biology and medicine has been gaining recognition and interest . An underlying component of this work is the additional degrees of complexity that biological systems introduce into surface interactions, and how they must be taken into account when considering design principles for the creation of materials for eventual technology translation.…”

Tuning the Density of Zwitterionic Polymer Brushes on PET Fabrics by Aminolysis: Effect on Antifouling Performances

“…In recent years, lubricant-infused surfaces have been found to reduce the lateral adhesion of all types of liquids and to limit bacteria and microorganisms surface interactions, although such surfaces often involve the use of non-environmentally friendly compounds [7][8][9][10][11].…”