Preparation And Properties Of A Novel Superhydrophobic Surface With High Stability And Low Adhesion

Superhydrophobic surface(SHPOS),that is,a surface having an apparent contact angle of water greater than 150° and a contact angle hysteresis(or rolling angle)of less than 10°,such as a lotus leaf surface,a beetle's back,a butterfly's wings,etc.In recent years,such surfaces have successfully attracted the attention of researchers,and have made important progress in the development and application,such as self-cleaning,antifouling,anti-freezing and drag reduction.However,there are still plenty of problems that need to be solved in the design,preparation and application of SHPOS.Firstly,the existing SHPOS preparation method is inferior in practicability.It requires not only fine manual operation but also the assistance of complicated and expensive instrument,and it is difficult to expand production.Secondly,the hydrophobic stability and durability of SHPOS are also hindered from being applied to practical applications.One of the serious problems is that,once the liquid layer collapses from the Cassie-Baxter state,its unique set of properties will no longer exist.Finally,only the rejection of water,still can not meet the daily clothing pollution-free,anti-fingerprint and anti-biohazard effects,so it is also necessary to achieve oil rejection.Therefore,it is necessary to select a simple method to prepare a surface having high stability of superhydrophobicity and superoleophobicity at the same time,that is,superamphiphobic surface(SAPOS).Here,we provide a simple dip-coating technique to easily obtain SHPOS and SAPOS with high stability and low adhesion.The specific research work is summarized as follows:(1)Preparation and properties of salvinia-like SHPOSAfter analysing the principle that the salvinia surface can long-term maintain the superhydrophobic effect underwater(ie,the hydrophilic top of the hydrophobic egg beater structure provides energy barriers to prevent liquid layer collapse)and the principle of the slippery nepenthes surface(ie lubrication infused in the porous structure provid slippery effect),by replacing the hydrophilic top of salvinia structure by a lubricating layer made from a PDMS layer impregnated with silicone oil,we successfully combined the above characteristics into one structure and get salvinia-like slippery SHPOS,which retains the energy barrier effect in the vertical direction of the salvinia surface and also lowers the adhesion of the surface on the horizontal direction under the impact of lubricant.Wherein,the stability of the surface is characterized by the measurement of the minimum external pressure required for the state transition of the droplet,the change of the droplet contact line during the evaporation process and droplet impact process.While the low adhesion is characterized by roll-off angle,microscopic receding angle,as well as the viscous force that a droplet needs to conquer to move on the surface.Finally,the water pressure resistance and drag reduction effect of the surface in the fluid pipeline were actually simulated by microfluidic experiments.Our work not only provides new ideas for the design of SHPOS surface,but also offer a quantitative basis for practical applications.(2)Preparation and properties of mushroom-like porous SAPOSAnalyzing the superamphiphobic principle of the soot-tempalted porous SAPOS and mushroom-like SAPOS,namely,graded rough structure and re-entrant rough structure created by low-surface tension materials,we successfully combine both of the structure into one stcuture by using a simple dip-coating technique,which not only work on the creation of the mushroom-like surface,but also on the transfer of the soottempalted porous structure to the top of the mushroom-like structure to obtain a mushroom-like porous SAPOS surface.The mushroom-like porous SAPOS has lower droplet adhesion than a single soot-tempalted porous SAPOS and a mushroom-like SAPOS surface,like glycerin droplet with high viscosity and tetradecane droplet with low surface tension.The successful development of this surface also provides new ideas for the design and preparation of SAPOS surfaces.