| There are many superhydrophobic phenomena in nature,and the surface of a lotus leaf is the most typical superhydrophobic surface with the self-cleaning property of being "immaculate".Other superhydrophobic surfaces such as lotus leaves have many micro-nanostructures,which are one of the important factors for the superhydrophobic properties of material surfaces.The use of different material processing techniques(e.g.sol-gel,electrostatic spinning,electrodeposition,embossing,laser processing,etc.)to build micro-nanostructures on material substrates and combine them with chemical modifications to prepare superhydrophobic surfaces is a hot research topic at home and abroad nowadays.The special wettability of superhydrophobic surfaces to water droplets makes them promising in the fields of self-cleaning,anti-corrosion,fog collection in arid regions and anti-freezing rain and anti-frost;meanwhile,researchers have found that superhydrophobic surfaces also have excellent resistance to bacterial adhesion,so exploratory research on the application of superhydrophobic surfaces in medical devices,materials science,biology and other fields is also underway.In recent years,researchers have found that the air layer formed by superhydrophobic surfaces with micro-nanostructures can repel many kinds of liquid droplets well,but the air layer formed by micro-nanostructures is easily damaged when subjected to external disturbances such as pressure.However,the researchers found that although the air layer on the material surface is easily damaged by external forces,the presence of the air layer facilitates the storage of lubricants such as silicone oil.Therefore,by coating the superhydrophobic surface with lubricants,the researchers obtained a slippery surface imitating pigweed that shows a sliding angle of less than10 ° to water droplets.When the superhydrophobic surface is coated with lubricant such as silicone oil,the lubricant-like substances can extrude air from the micronanostructures into the grooves of the air layer and form a stable oil film on the superhydrophobic surface,at which point the surface is transformed from a superhydrophobic surface to a slippery surface.Compared with superhydrophobic surfaces,slippery surfaces have better mechanical stability due to the presence of oil film,and have promising applications in liquid transportation,control of chemical reactions,and self-healing materials.Both superhydrophobic and slippery surfaces require pre-construction of suitable micro-nanostructures on the material surface.Among many micro-nanostructure processing methods,femtosecond laser processing has attracted a lot of attention because of its good applicability to different substrates(metals,ceramics,polymers,glass,etc.),high processing efficiency and simple process flow.The paper focuses on the preparation of superhydrophobic and slippery surfaces with different functions through femtosecond laser processing combined with different modifications to explore their applications in corrosion resistance,low adhesion,antibacterial and so on,and some remarkable results have been achieved.The main contents are as follows.1.The superhydrophobic metallic aluminum(Al)surfaces were prepared by femtosecond laser processing combined with chemical modification,allowing them to effectively resist corrosion by ethylene glycol solutions.The corrosion rate of the superhydrophobic surface was reduced by 3 orders of magnitude compared to the untreated planar sample,and the retardation rate was up to 98 %,allowing the material to be used in a wider range of engineering applications.2.The slippery surface that can repel fecal simulants is obtained by femtosecond laser processing combined with a silicone oil coating and a hybrid coating of polydimethylsiloxane(PDMS)and silicone oil.At the same time,the mechanism of the surface repelling the fecal simulant was explained,and the surface was applied to the flush door of the optimized toilet to reduce or eliminate the need for flushing in order to advance the sanitation action project.Based on the slippery surface that repels the fecal simulant,this work optimizes an ordinary squatting toilet by changing the original squatting toilet into a urine-fecal separation toilet,adding a flap door to the fecal dropoff section to prevent odor diffusion and mosquitoes from contacting the feces,and creating a model of a simple solid-liquid separation toilet.3.The superhydrophobic 316 L stainless steel surface with antibacterial properties and anti-cell adhesion properties was prepared by femtosecond laser processing only combined with heating without any chemical coating.This material surface can effectively reduce the adhesion of bacteria and cells on the 316 L stainless steel surface,which provides an important reference for the design and use of medical devices.Through the above work,the effective preparation of superhydrophobic/slippery surfaces and their specific application studies were achieved.The combination of femtosecond laser processing and chemical coating modification makes it possible to achieve excellent results in anti-corrosion,anti-adhesive solid adhesion and antibacterial,which have great prospects for application in daily life. |
