Slippery Lubricant‐Infused Surfaces: Properties and Emerging Applications

Abstract

Bioinspired lubricant-infused surfaces exhibit various unique properties attributed to their liquid-like and molecularly smooth nature. Excellent liquid repellency and "slippery" properties, self-healing, antiicing, anticorrosion characteristics, enhanced heat transfer, antibiofouling, and cell-repellent properties have been already demonstrated. This progress report highlights some of the recent developments in this rapidly growing area, focusing on properties of lubricant-infused surfaces, and their emerging applications as well as some future challenges.coatings. [8] In order to solve the abovementioned limitations of traditional superhydrophobic and superoleophobic surfaces, Quéré, Aizenberg, and Varanasi proposed bioinspired slippery liquidinfused porous surface (SLIPS) or lubricant-impregnated surfaces combining the mechanical stability of a solid substrate with the liquid-like properties and molecularly smoothness of the lubricant interface. [9a-d] It should be noted that stabilization of a lubricant layer on solid surfaces by forming a thin polymer film that can be swollen in the lubricant was introduced in 1988 by Karakelle and Zdrahala from Bekton, Dickinson and Company.[9e] They also demonstrated excellent long-term stability, liquid repellency, and proposed various medical applications of lubricant-impregnated surfaces. SLIPSs mimic the Nepenthes pitcher plant surface, [10] which is textured and can be lubricated with an aqueous solution. [11] The unique slippery character of the [9a] Nepenthes pitcher plant's surface resulting from water lubrication helps it capture insects sliding into its interior. To mimic the Nepenthes pitcher plant surface, a lubricating hydrophobic liquid can be infused into different hydrophobic porous or rough substrates to form SLIPS. [9] By matching the surface energy of the underlying porous substrate and the hydrophobic lubricant, the liquid can be stabilized on the surface of the substrate to form SLIPS. [9a] Depending on the impregnated lubricant, SLIPSs possess excellent repellency and drop mobility to a broad range of liquids including low surface tension liquids, and complex fluids such as blood or cell medium. [9a] This liquid repellency as well as SLIPS′ self-healing properties are due to the mobility of the lubricant trapped inside the porous surface structures. [12] Lubricant-infused surfaces demonstrated icephobic, stainresistant, biofilm-or cell-repellent or marine antibiofouling properties as well as tolerance to high pressure and transparency. [9,13] All of these unique properties make SLIPS interesting for the development of novel functional materials and various practical applications.The goal of this progress report is not to comprehensively review this broad and dynamic research field but rather highlight selected important aspects that have been less reviewed so far despite their potential. Some important and related papers could not be cited due to the length limitations. We also refer readers to several excellent reviews covering applications of ...

A Biomimetic Approach to Increasing Soft Actuator Performance by Friction Reduction

“…Clearly, the effect of the hydrophobic PDMS coating is much larger in the mixed electrolyte solution. This superposition of the effects can be explained by the interaction of the amphiphilic electrolyte with the hydrophobic PDMS coating, emerging in a highly slippery interface [13], similarly to lubrication effects of the Nepenthes pitcher plants, which apply the infusion of a lubricating hydrophobic liquid into a hydrophobic rough substrate to achieve super-slippery surfaces [52]. Interestingly, in the present case, similar phenomena appear to take place in a solution.…”

“…Reduction of friction is a common approach in many fields of engineering and technology. Using hydrophobic polymeric surfaces such as those of PDMS [9,10] is one of the mayor approaches to increasing the motion of fluids in micro fluidics [11] for micro-electro-mechanical system applications [12], biomedical applications [13], electrowetting applications [14], and switchable adhesion surfaces in robotic devices leaning on the gecko-feet adaptation [15].…”

External Stimuli Responsive Liquid‐Infused Surfaces Switching between Slippery and Nonslippery States: Fabrications and Applications

“…Similar to Wong's work, a serial of liquid‐infused surfaces, or so called lubricant‐infused surfaces (LIS)14j have been fabricated by infusing or swelling lubricants into various substrates . The adopted substrates should be porous, rough, or swellable in the lubricant . LIS have realized repellency of various liquids, including ice, aerosol, ionic liquid, underwater bubbles, low surface tension liquid, complex fluids such as blood, liquids contained bacteria or cell,14j,30 seawater contained marine organism and so on 22,23b,32.…”

Fluorine‐Free Slippery Liquid‐Infused Porous Surfaces Prepared Using Hierarchically Porous Aluminum

“…It was demonstrated that SLIPS are also icephobic . Superhydrophobic surfaces with micro‐/nanotextured surface morphologies and low‐surface‐energy coatings possess several drawbacks including repellency only to liquids with high surface tensions (wetting to low‐surface‐tension oils), low mechanical stability, and irreversible Cassie‐to‐Wenzel transition . These drawbacks can be overcome when SLIPS materials are used instead of superhydrophobic surfaces, although it is often pointed out that lubricant oil retention is a weakness of SLIPS .…”