Superhydrophobic Surfaces Fabricated By Femtosecond Laser Pulses And Study On Their Wettability

In recent years,superhydrophobic surfaces have received much attention due to their significant non-wetting property and self-cleaning.They have broad potential applications in scientific and engineering fields.Over the past few years,femtosecond laser pulse ablation has become a novel and versatile approach to fabricate superhydrophobic surface due to its flexibility,simplicity,and capability of producing a large variety of surface structures.Surface morphology plays an important role in the wettability of the surface.We attempt to obtain superhydrophobic surfaces by mimicking the dual hierarchical structure on the lotus leaf.In this work,micro/nano structures on various materials including aluminum alloy,stainless steel and polytetra-fluoroethylene(PTFE)have been fabricated by femtosecond laser pulses.The process parameters including laser pulse energy,scan speed,groove distance have been varied to investigate their effects on the wettability of surfaces.The SEM picture shows that the diameter and depth of ablation crater,the height of the pillar and spacing between pillars can affect the morphologies on sample surface.By increasing laser pulse energy,decreasing scanning speed and groove distance,a fine structure can be achieve.Fluorinated alkylsilane agent was used to further decrease the surface energy.Apparent contact study revealed that when the surface poses micro/nano structure,it could nearly approach to superhydrophobic.The durability of the sample surface is investigated in air at room temperature.Few months later,the surface still repels to the water droplet.To expand on applications,a certain pattern was designed on the PTFE surface which could exhibit different wettability when the water droplet falls down on it.