Repelling liquid drops from engineering surfaces has attracted great attention in a variety of applications.To achieve efficient liquid shedding,delicate surface textures are often introduced to sustain air pockets at...Repelling liquid drops from engineering surfaces has attracted great attention in a variety of applications.To achieve efficient liquid shedding,delicate surface textures are often introduced to sustain air pockets at the liquid-solid interface.However,those surfaces are prone to suffer from mechanical failure,which may bring reliability issues and thus limits their applications.Here,inspired by the aerodynamic Leidenfrost effect,we present that impacting drops are directionally repelled from smooth surfaces supplied with an exogenous air layer.Our theoretical analysis reveals that the synchronized nonwetting and oblique bouncing behavior is attributed to the aerodynamic force arising from the air layer.The versatility and practicability of our approach allow for drop repellency without the aid of any surface wettability treatment and also avoid the consideration of mechanical stability issues,which thereby provides a promising candidate for the applications that necessitate liquid shedding,e.g.,resolve the problem of tiny raindrop adhesion on the automobile side window during driving.展开更多
It is well-known that microscale gaps or defects are ubiquitous and can be penetrated by vapor,resulting in the failure of superhydrophobic effect and undesired condensate flooding under high subcooling.Here,we propos...It is well-known that microscale gaps or defects are ubiquitous and can be penetrated by vapor,resulting in the failure of superhydrophobic effect and undesired condensate flooding under high subcooling.Here,we propose and demonstrate that such problem can be solved by the oblique arrangement of nanowires.Such a structure has been demonstrated to own anti-vapor-penetration and microdrop self-transport functions under high subcooling,unaffected by the microscale gaps.This is because vapor molecules can be intercepted by oblique nanowires and preferentially nucleate at near-surface locations,avoiding the penetration of vapor into the microscale gaps.As-formed microdrops can suspend upon the nanowires and have low solid-liquid adhesion.Besides,oblique nanowires can generate asymmetric surface tension and microdrop coalescence can release driving energy,both of which facilitate the microdrop self-removal via sweeping and jumping ways.This new design idea helps develop more advanced condensation mass and heat transfer interfaces.展开更多
CONSPECTUS:A super-repellent surface is a type of liquid-repellency material that allows for various liquid drops to bead up,roll off,or even bounce back.Known for its ability to remain dry,perform self-cleaning,and h...CONSPECTUS:A super-repellent surface is a type of liquid-repellency material that allows for various liquid drops to bead up,roll off,or even bounce back.Known for its ability to remain dry,perform self-cleaning,and have a low adhesion,a super-repellent surface presents great advantages in a number of applications.These include antifogging,anti-icing,oil/water separation,and fluid drag reduction.To fend off the liquids or drops,super-repellent surfaces combine the merits of surface chemistry and physical structure.By taking advantage of a low surface energy to prevent liquid from spreading,the super-repellent surfaces utilize the micronano structure to provide a framework that confines the solid−liquid interactions.Compared to beading up the drop of water,the repellence of liquid with low surface tension requires the subtle design of surface structure to resist the wetting of liquids.However,the inherent instabilities of the fragile micronano structure of super-repellent surfaces and solid−liquid interactions further make the fabrication of super-repellent surfaces complex to withstand dynamic environments(friction or wear)during application.In addition,the transparency and thermal stability of super-repellent surfaces are also the restrictive factors in some special application scenarios.To solve these challenges,durable super-repellent surfaces that can repel various liquids,possess robust mechanical and thermal stability,and show high transparency have been explored extensively in recent years.展开更多
基金support by the National Natural Science Foundation of China(22202035,22072014,and 22102017)the Chengdu Science and Technology Bureau(2021-GH02-00105-HZ)+3 种基金the Shenzhen Science and Technology Program(JCYJ20210324142210027)the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province(2021ZYD0046)the Sichuan Outstanding Young Scholars Foundation(2021JDJQ0013)the Sichuan Science and Technology Program(2021JDRC0016).
文摘Repelling liquid drops from engineering surfaces has attracted great attention in a variety of applications.To achieve efficient liquid shedding,delicate surface textures are often introduced to sustain air pockets at the liquid-solid interface.However,those surfaces are prone to suffer from mechanical failure,which may bring reliability issues and thus limits their applications.Here,inspired by the aerodynamic Leidenfrost effect,we present that impacting drops are directionally repelled from smooth surfaces supplied with an exogenous air layer.Our theoretical analysis reveals that the synchronized nonwetting and oblique bouncing behavior is attributed to the aerodynamic force arising from the air layer.The versatility and practicability of our approach allow for drop repellency without the aid of any surface wettability treatment and also avoid the consideration of mechanical stability issues,which thereby provides a promising candidate for the applications that necessitate liquid shedding,e.g.,resolve the problem of tiny raindrop adhesion on the automobile side window during driving.
基金This work was supported by National Key R&D Program of China(No.2017YFB0406100)the National Natural Science Foundation of China(No.21573276)Natural Science Foundation of Jiangsu Province(Nos.BK20170007 and BK20170425).
文摘It is well-known that microscale gaps or defects are ubiquitous and can be penetrated by vapor,resulting in the failure of superhydrophobic effect and undesired condensate flooding under high subcooling.Here,we propose and demonstrate that such problem can be solved by the oblique arrangement of nanowires.Such a structure has been demonstrated to own anti-vapor-penetration and microdrop self-transport functions under high subcooling,unaffected by the microscale gaps.This is because vapor molecules can be intercepted by oblique nanowires and preferentially nucleate at near-surface locations,avoiding the penetration of vapor into the microscale gaps.As-formed microdrops can suspend upon the nanowires and have low solid-liquid adhesion.Besides,oblique nanowires can generate asymmetric surface tension and microdrop coalescence can release driving energy,both of which facilitate the microdrop self-removal via sweeping and jumping ways.This new design idea helps develop more advanced condensation mass and heat transfer interfaces.
基金We acknowledge funding support by the National Natural Science Foundation of China(22072014)the Fundamental Research Funds for the Central Universities(ZYGX2019J119)+2 种基金Max-Planck-Gesellschaft(Max Plank Partner Group UESTCMPIP)the Sichuan Science and Technology Program(2021JDRC0016)the Sichuan Outstanding Young Scholars Foundation(21JCQN0235).
文摘CONSPECTUS:A super-repellent surface is a type of liquid-repellency material that allows for various liquid drops to bead up,roll off,or even bounce back.Known for its ability to remain dry,perform self-cleaning,and have a low adhesion,a super-repellent surface presents great advantages in a number of applications.These include antifogging,anti-icing,oil/water separation,and fluid drag reduction.To fend off the liquids or drops,super-repellent surfaces combine the merits of surface chemistry and physical structure.By taking advantage of a low surface energy to prevent liquid from spreading,the super-repellent surfaces utilize the micronano structure to provide a framework that confines the solid−liquid interactions.Compared to beading up the drop of water,the repellence of liquid with low surface tension requires the subtle design of surface structure to resist the wetting of liquids.However,the inherent instabilities of the fragile micronano structure of super-repellent surfaces and solid−liquid interactions further make the fabrication of super-repellent surfaces complex to withstand dynamic environments(friction or wear)during application.In addition,the transparency and thermal stability of super-repellent surfaces are also the restrictive factors in some special application scenarios.To solve these challenges,durable super-repellent surfaces that can repel various liquids,possess robust mechanical and thermal stability,and show high transparency have been explored extensively in recent years.
