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Fabricating a Hydrophobic Cu Surface with Multiscale Microtextures Using Laser Shock Imprinting (LSI)
L. Zhang, Z-B. Shen, P. Li, Y-Y. Lin, K. Liu, G-Y. Zhou, Y. Wang, H-X. Liu and X. Wang

Laser shock imprinting (LSI) is used to fabricate a hydrophobic Cu surface with multiscale microtextures in this work. To obtain multiscale microtextures in a micromould, a first pass of laser marking was used to increase the roughness of the original surface. Then a second pass of laser marking was used to manufacture periodic groove microstructures on the micromould. Thereafter, LSI was used to replicate the multiscale microtextures of the micromould on the sample surface. The surface morphology, wettability and surface roughness of samples fabricated at different laser shock energies were investigated. The experimental results indicate that the sample can successfully replicate the microtextures of the micromould surface after LSI and the greater the laser shock energy, the higher the degree of replication of the sample to the microtextures of the micromould. As the laser shock energy increases from 620 to 1290 mJ, the profile and roughness of microtextures of sample surface gradually close to those of micromould. In addition, the static contact angles measurement results show that the sample surface wettability changes from hydrophilic to hydrophobic after LSI, and the contact angles increase with the increase of laser shock energy. Due to the anisotropic wettability, the static contact angles perpendicular to groove microstructures are apparently larger than that in the parallel direction. The maximum static contact angles of the sample in perpendicular and parallel directions are 124 and 109°, respectively, when the laser shock energy was 1290 mJ. This work provides a new approach for fabricating hydrophobic surfaces, which can realize the wider practical production value of LSI in the direction of preparing superhydrophobic surfaces.

Keywords: Fibre laser, Nd:YAG laser, copper, Cu, aluminium foil, laser shock imprinting (LSI), surface roughness, surface morphology, wettability, groove

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