仿生超滑涂层研究进展

Research progress in bioinspired slippery coatings

仿生超滑涂层因具有优异的拒液性、自愈性和高压稳定性,在防污、抗黏附和防结冰等应用领域受到广泛关注。将润滑油注入多孔基体获得的注液超滑涂层或在光滑平面接枝润滑分子获得的类液体超滑涂层均可获得上述优异性能。然而,超滑涂层面临润滑层易损耗、机械稳定性不足等问题,在实际应用中仍存在一定局限性。该文在总结注液超滑表面仿生设计原理的基础上,详细介绍了注液超滑涂层和类液体超滑涂层的特点与研究进展,并指出当前面临的问题。此外,从高可靠性、长寿命超滑涂层的优化设计制造角度,评述了超滑涂层的发展趋势。

[Significance]Bioinspired slippery coatings have attracted extensive attention in antifouling,anti-adhesion,and anti-icing applications because of their excellent liquid repellency,self-healing properties,and high-pressure stability.The slippery liquid-infused coating obtained by infusing lubricating oil into porous matrixes and the slippery liquid-like coating afforded by grafting lubricating molecules onto smooth surfaces exhibit the aforementioned properties.However,some limitations still hinder the practical applications of these coatings,such as easy loss of the lubrication layer and insufficient mechanical stability.Therefore,this study introduces the characteristics and research progress of slippery liquid-infused and slippery liquid-like coatings in detail by summarizing the bionic design principles of slippery liquid-infused surfaces.Furthermore,the existing problems related to coatings are highlighted.[Progress]According to the oil fixation mechanism and lubrication layer thickness,slippery coatings could be divided into three categories.Type 1D slippery coatings,known as slippery liquid-like coatings,mainly stabilize the lubrication layer by chemical grafting;thus,they showed good stability when subjected to gravity,shear force,and water scouring.However,they easily lost their slippery performance when subjected to mechanical wear due to their low thickness and poor wear resistance.The fabrication of type 1D-slippery coatings involved complex preparation processes,harsh preparation conditions,and high costs,limiting their large-scale applications.Type 2D-and 3D-slippery coatings stabilized the lubrication layer through their porous structures.Type 2D-slippery coatings exhibited good mechanical stability and could be easily prepared.However,due to their poor oil-fixing performance,the lubricating oil was easily lost,and they could not recover the oil themselves.Therefore,maintaining their slippery properties for a long time under harsh conditions was challenging.To solve this problem,researchers had conducted several studies on structural design and chemical modification.Despite their effective efforts,the porous structures of type 2D-slippery coatings could only store a small amount of lubricating oil,and the timely replenishment of oil after oil loss remained difficult.Type 3D-slippery coatings included gel and nongel coatings.Gel cross-linked networks and 3D porous physical structures could store/release lubricating oil,thereby improving the slippery stability of these coatings.With the introduction of smart materials,type 3D-slippery coatings could actively adjust the release of lubricating oil according to changes in the environment and coating states.However,the 3D-gel and-nongel slippery coatings exhibited insufficient mechanical stability and weaked oil control-release ability,respectively.[Conclusions and Prospects]To prepare highly reliable and long-life slippery coatings for large-scale industrial applications,further research is required.First,we need to understand the storage,fixation,and release mechanisms of the lubricating oil in slippery coatings,introduce intelligent materials,and systematically study the influence of structural characteristics,chemical compositions,and preparation methods on the stability of coatings.Second,the influence of lubricating oil on the adhesive strength of coatings must be further investigated because the lubricating oil may affect the bonding properties between the coatings and substrates.Additionally,the coating preparation methods should be simplified,and costs must be reduced to promote the applications of bioinspired slippery coatings.To achieve green production,more attention should be paid to the use of environmentally friendly materials in coating preparation processes.Finally,new slippery coatings need to be developed according to practical application environments by mimicking multiple biological templates.