Fabricatiion Of Tunable Wetting Surfaces By Laser Texturing Technology

Wettability is one of the significant properties of solid surface,which is codetermined by surface roughness and surface energy.The wettability can be intelligently controlled by the surface micro-structure and chemical component.Inspired by the “lotus effect” and “petal effect”,biomimetic superhydrophobic and superhydrophilic surfaces have been fabricated on different substrates through various technologies.As a precise micro-machining tool,laser beam has been widely used to construct micro-nano rough structures on metal surface.In the thesis,micro-nano rough structures on different metal surfaces were obtained by laser etching,and chemical treatments were employed to reduce the surface energy,finally the surfaces with tunable wettability were achieved.The main results are as follows:1?Starting with the analysis of the difference between Wenzel and Cassie wetting state,a temporal-spatial design method based on laser etching was proposed to manufacture surfaces with tunable wettability.A kind of micro-nano self-assembly structure based on temporal-spatial regulated wettability was designed,and the preparation process was analyzed.By adjusting the temperature,the wettability of the laser textured surface with chemical modification can be exchanged between superhydrophilicity and superhydrophobicity.The surface with tunable wettability may have important applications in intelligent microfluidic switching,fuel cell and phase transition heat transfer.2?Superhydrophobic copper surface was fabricated with nanosecond laser etching and ethanol assisted fast low-temperature annealing,the max contact angle of 161° was achieved.The superhydrophobicity of the prepared surface will vanish after ultrasonic vibration and cleaning,but it can be reacquired through ethanol assisted fast lowtemperature annealing again,which means that the superhydrophobicity is renewable.The ability of tuning the high adhesion by adjusting the laser scanning spacing was characterized through a self-built equivalent inertial force system.And the application potential of this superhydrophobic surface with tunable high adhesion on droplets transport was demonstrated in an experiment.3?A low adhesion superhydrophobic(LASH)titanium surface with periodical structure and micro-nano hierarchical structure was fabricated by laser etching and low surface energy reagent modification,the max contact angle reached to 162.3°,and the slide angle was only 2°.The deposited area of the nanoparticles suspended in droplet on LASH surface is 265.56 times smaller than that of the original surface.For achieving a patterned superhydrophilic/superhydrophobic composite structure,the modification layer formed by low surface energy reagent was removed by the laser etching according to designed patterns.The shape and size of the deposited patterns can be controlled by adjusting the designed superhydrophilic patterns.Surfaces with extreme wettability(superhydrophilic,superhydrophobic,hybrid superhydrophilic-phobic structure)have great potential applications in bionic engineering,microfluid,self-assembly and biomedicine.The promising superiority of precise laser etching technology in fabricating tunable-wettability surface was demonstrated by this thesis,which provides a common technical foundation for future engineering applications.