Selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles (NPs) for facile controllable fabrication of super-hydrophobic surface

A method of selective laser melting of ink-printed (SLM-IP) Cu nanoparticles (NPs) for facile controllable fabrication of super-hydrophobic surface structure is reported in this paper. A hierarchical structure composed of micro/nano-scaling copper (Cu) meshing texture was obtained by SLM-IP NPs. The meshing sizes are varied from 0.05 mm to 0.23 mm. By applying the analysis of SEM, XRD, Confocal Laser Scanning Microscope (CLSM), apparent contact angle (CA) measurement and water droplet dynamic behavior analysis, the effects of both mesh size and nano-sized structures on the hydrophobicity were discussed. The results show that the mesh surface fabricated by SLM-IP Cu NPs expresses an excellent super-hydrophobicity with a CA as high as 160° and sliding angle as low as 3.9° with a mesh grid size of 0.05 mm. An apparent CA model for double roughness structure was used to predict the CAs. The calculated CAs show a good agreement with the measurements when the mesh grid size is far less than the radius of water drop. SLM-IP Cu NPs takes the advantages of additive manufacturing and provides a flexible way for the functional surface structure fabrication.