Recent advances in slippery liquid-infused surfaces with unique properties inspired by nature

Abstract

The slippery liquid-infused porous surface(s) (SLIPS) that imitates the Nepenthes pitcher plant has proven to be highly versatile and can be combined with various surface characteristics such as dynamic response, antifouling, selective adhesion, and optical/mechanical tunability. In addition, the introduction of a lubricating fluid layer also gives it extremely low contact angle hysteresis and self-repairing properties, which further expands its application range. Currently, SLIPS has been proven to be suitable for many frontier fields such as aerospace, communications, biomedicine, and microfluidic manipulation. In this review, we explain the theoretical background of SLIPS and the preparation methods currently available, including the choice of substrate materials and lubricants, and we discuss the design parameters of the liquid injection surface and how to deal with the consumption of lubricants in practical applications. In addition, the paper focuses on current and potential applications, such as preventing pathogen contamination of and blood adhesion of medical equipment, manipulation of tiny droplets, and directional transportation of liquids. Finally, some weaknesses that appear when SLIPS is used in these applications are pointed out, which provides a new perspective for the development of SLIPS in the future.

Study of the Droplet Pinning Force in the Transition from Dry to Liquid-Infused Thin Polymer Films

“…The presence of a thin liquid lubricant layer on the surface results in self-healing coatings with pressure-stable repellency to water, oils, blood, and other test liquidsextremely low values of contact angle hysteresis (CAH) and sliding angles (SA) are observed. SLIPS possess antimicrobial and anti-icing properties, selective adhesion, and optical/mechanical tunability, and can find applications in aerospace, biomedicine, microfluidic manipulation, and directional transportation of liquids. − …”

“…Both rough and smooth porous matrices are used; the surface can be additionally functionalized to enhance the lubricant molecules’ interaction with the matrix. Metals, inorganic nonmetallic materials, and porous polymers are usually used to create matrices . Commonly used lubricants include fluorinated polyethers, silicone, or mineral oils and ionic liquids.…”

“…Kreder et al showed that growing the wrapping layer is the dominant source of depletion . The methods for improving durability include using high-viscosity lubricants, designing systems capable of replenishing the lubricant layer (e.g., by creating interconnected porous structures, which can store the liquid inside the matrix), and enhancing the interaction between the lubricant and the substrate. , …”

“…Metals, inorganic nonmetallic materials, and porous polymers are usually used to create matrices. 4 Commonly used lubricants include fluorinated polyethers, silicone, or mineral oils and ionic liquids. An important condition for the finished coating stability is a strong intermolecular interaction between the lubricant and the matrix.…”

“…13 The methods for improving durability include using high-viscosity lubricants, designing systems capable of replenishing the lubricant layer (e.g., by creating interconnected porous structures, which can store the liquid inside the matrix), and enhancing the interaction between the lubricant and the substrate. 4,14 Thus, the study of the pinning force and slippery property dependence on the parameters of the SLIPS system seems to be important both for the development of a theoretical description of such coatings and for the design of durable coatings. From this point of view, SLIPS based on polymer gels are of particular interest because it is possible to effectively control their properties by varying the gel parameters (degree of crosslinking, type of cross-links in the matrix, and viscosity and composition of the solvent).…”