利用液固界面摩擦力表征经典特殊润湿性生物表面  

Characterization of Classical Biological Surfaces with Special Wettabilities by Liquid-Solid Friction Force

作　　者：张晋红 石奎[1] 徐鹏 李倩 薛龙建[1] ZHANG Jin-hong;SHI Kui;XU Peng;LI Qian;XUE Long-jian(School of Power and Mechanical Engineering,Wuhan University,Wuhan 430072,China;Department of Mechanical Engineering,Shanxi Polytechnic College,Taiyuan 030006,China)

机构地区：[1]武汉大学动力与机械学院,武汉430072 [2]山西职业技术学院机械工程系,太原030006

出　　处：《表面技术》2021年第7期187-193,共7页Surface Technology

基　　金：科技部重点研发计划(2018YFB1105100);国家自然科学基金(51973165)。

摘　　要：目的用毛细管投影传感技术(MPCP)定量表征经典生物材料表面的液固界面摩擦力,揭示滚动角测试所无法揭示的液固界面作用规律。方法利用毛细管投影传感技术(MPCP)表征了水滴在荷叶、玫瑰花瓣和蝴蝶翅膀表面的摩擦力,并进一步探讨了样品干燥、水滴大小和移动速度对液固摩擦力的影响规律。结果当液滴体积由2μL增大到10μL时,水滴在新鲜荷叶表面的静摩擦力F_(S)从(10.01±0.75)μN增大到(15.99±1.99)μN,动摩擦力F_(K)由(9.10±1.30)μN增大到(11.31±0.75)μN;干燥过程使得FS由(22.11±3.44)μN上升到(34.72±1.99)μN,F_(K)由(10.40±0.75)μN增大到(20.42±3.00)μN。与荷叶不同的是,新鲜玫瑰花瓣的静摩擦力F_(S)和动摩擦力F_(K)均高于冻干玫瑰花瓣,且随着水滴尺寸的增大而明显增大。由于蝴蝶翅膀结构的各项异性,顺着蝴蝶翅膀D_(F)方向的F_(S)和F_(K)比反向D_(O)方向要明显小一些,有利于水滴从体表滚落。当液滴移动速度由0.05mm/s增大到2.05mm/s时,荷叶表面的F_(S)和F_(K)变化不明显;新鲜玫瑰花瓣的F_(S)由(70.22±1.99)μN减小到(60.21±1.99)μN,F_(K)由(44.21±2.25)μN显著减小到(18.21±1.30)μN。而冻干玫瑰花瓣表面的F_(S)和F_(K),随着液滴移动速度的增大而略微减小。蝴蝶翅膀的摩擦力对液滴移动速度表现出一定的方向依赖性,随着液滴移动速度的增大,D_(F)向的F_(S)和F_(K)保持恒定,而D_(O)向的F_(S)和F_(K)减小则显著一些。结论用毛细管投影传感技术MPCP可以揭示水滴在固体表面的摩擦特征,定量表征摩擦力,弥补了滚动角只能表征液滴滚落一瞬间固体对水滴滑动的阻力,无法表征液固动摩擦的不足;定量地揭示了样品干燥、水滴大小和移动速度对水滴在荷叶、玫瑰花瓣和蝴蝶翅膀表面摩擦力的影响规律。Contact angle and sliding angle are usually used to characterize the wettability of solid surfaces,though the technique has its own inherent limitations.In the current work,a newly established technique for the measurement of liquid-solid interfacial friction is employed to quantitatively characterize the classical biological surfaces with superwettabilities,including lotus leaves,rose petals and butterfly wings.The liquid-solid friction forces of these classical surfaces are characterized by the technique of MPCP(monitoring the projection of capillary position).The influences of sample drying,size and moving velocity of water droplet on the liquid-solid friction force are also discussed.When the droplet volume is increased from 2μL to 10μL,the static friction force,F_(S),of fresh lotus leaves increases from(10.01±0.75)μN to(15.99±1.99)μN,while the kinetic friction force,F_(K),slightly increases from(9.10±1.30)μN to(11.31±0.75)μN.The drying process increases both the F_(S) and F_(K) of lotus leaves that F_(S) increases from(22.11±3.44)μN to(34.72±1.99)μN,and F_(K) increases from(10.40±0.75)μN to(20.42±3.00)μN upon the increase of droplet volume.Different from lotus leaves,both F_(S) and F_(K) of rose petals increase significantly upon the droplet-volume increase,and are larger than that of the dried ones.Due to the anisotropic structures on butterfly wing,F_(S) and F_(K) along the D_(F) direction of butterfly wings are significantly smaller than that along D_(O) direction,facilitating the rolling off of water droplets.When the moving speed of the droplet increases from 0.05 mm/s to 2.05 mm/s,F_(S) and F_(K) do not change obviously;in contrast,F_(S) of fresh rose petals decreases from(70.22±1.99)μN to(60.21±1.99)μN,and F_(K) significantly decreases from(44.21±2.25)μN to(18.21±1.30)μN,while F_(S) and F_(K) of dried rose petals slightly decreases.The velocity dependence on butterfly wings shows directional dependence that F_(S) and F_(K) along D_(F) direction are almost constant and signifi

关 键 词：表面润湿性 接触角 滚动角 摩擦力 毛细管投影传感技术 

分 类 号：TH117[机械工程—机械设计及理论] TB34[一般工业技术—材料科学与工程]