Multifunction of Biomimetic Liquid Infused Systems Derived from SLIPS Theory: A Review

Abstract

On this basis, two theoretical models appeared to the world. In 1936, Wenzel added a surface roughness factor "r" to Young's equations. [7] In 1944, Cassie and Baxter showed that the composite interface of solid and air can affect the superhydrophobicity. [8] Since then, the theory and analysis of surface has aroused enormous interest among scientists and researchers. In 1997, Barthlott and Neinhuis proposed the "lotus effect," [9] which is a hydrophobic and self-cleaning effect originated from the hierarchical structure of lotus leaves. A flurry of research on superhydrophobic surfaces came after that. Gradually, research on fabrication of surfaces with special wetting property became popular.The commonly used materials for daily applications contain textiles, glass, metal, and their alloys whose surfaces can be protected from being wetted, contaminated, or fouled by water and oil pollutants. Most metal materials will inevitably be oxidized when they encounter common liquid corrosion media, such as water, and the oxide film cannot effectively protect them. If the metal is covered with superhydrophobic surface, the air cushion contained in the micro-nano composite structure on the surface will protect the metal and separate the direct contact between the substrate and the liquid. It makes it difficult for corrosive ions to reach the metal surface, which significantly improves the corrosion resistance of the metal. However, the air cushion is unstable and easily replaced by liquid under external pressure and high temperature, losing its superhydrophobicity and corroded by liquid.At present, there are two main research directions of liquid repelling surfaces: Cassie-Baxter water contact state surfaces and lubricant-liquid contact state surfaces. The Cassie-Baxter contact surface designation was inspired by lotus leaves, butterfly wings and Inaba, mainly included superamphiphobic, superhydrophobic, and superoleophobic surfaces. These artificial surfaces can be combinate by low surface energy substance modification and micro-nano structures. Besides, with the inspiration of Nepenthes, lubricant-liquid contact state surfaces are designed. In 2011, Joanna Aizenberg of Harvard University and her colleagues first introduced "slippery liquid infused porous surface" (SLIPS)-that each consist of a film of lubricating liquid locked in place by a micro/nano porous substrate. [10] Compared with superhydrophobic surface, its air layer is replaced by immiscible liquid layer, which provides a more Slippery liquid infused porous surface (SLIPS) inspired by the microstructure of carnivorous Nepenthes has the potential to be used in a wide range of fields, including nautical, industrial, medical, etc. Due to their excellent optical transparency, self-healing after mechanical injury and controllable wetting properties, SLIPS has attracted extensive research interest. With appropriate lubricants, sufficient performance will be armed to the surface so as to adapt for further requirements. In this review, the first part focuses on the b...

Engineered Sustainable Omniphobic Coatings to Control Liquid Spreading on Food-Contact Materials

“…The rims of the pitcher plant are extremely slippery (when wet) due to the presence of a nonwettable microtextured surface that enables them to hold a thin aqueous layer, creating a highly slippery interface . Insects that step onto a wet peristome surface lose their footing and slip down to the digestive juice at the bottom, where a pool of digestive juices breaks them down, releasing nutrients to the plant . As with the properties of other highly nonwetting natural surfaces, the properties of the peristome are governed by the combination of surface chemistry and geometrical topographies. , Observation of the morphological structure of the peristome using SEM showed a thickness of ∼ 3 mm with a highly regular and smooth microstructure (Figure b).…”

“…Specifically, food scientists are embracing organic and food-grade wax-like materials for lowering surface energy. 26 Despite years of rapid and continuous research and development toward the formulation of biomimetic surfaces, the food-safety considerations pertaining to their engineering design, green production, and potential food-contact applications remain underrepresented in the literature.…”

“…With increasing concerns regarding fluorinated compounds entering the environment and the human body, researchers have begun to systematically investigate other safer and fluorine-free pathways to create surface micro/nanostructures with reduced surface energy. Specifically, food scientists are embracing organic and food-grade wax-like materials for lowering surface energy . Despite years of rapid and continuous research and development toward the formulation of biomimetic surfaces, the food-safety considerations pertaining to their engineering design, green production, and potential food-contact applications remain underrepresented in the literature.…”

Multi-component liquid-infused systems: a new approach to functional coatings

“…The addition of a liquid layer on the surface of a material to create a stable yet mobile coating is a relatively recent concept in materials science. These materials, referred to as liquid-infused surfaces (LIS), [1][2][3] slippery liquid-infused porous surfaces (SLIPS), [4][5][6][7] or infused polymers, [8][9][10][11] depending on their particular form, leverage the fluid characteristics of liquids to attain unique properties that are difficult to achieve with solid materials, such as ultra-low adhesion, 12,13 self-healing, 4,14,15 and even selfreplenishment. 9 Several excellent reviews are available that cover the fundamental physics of liquid-infused surfaces in depth.…”