Wettability of laser-textured copper surface after a water-bath process

Although the wettability of ultrafast laser-textured surfaces has been widely studied recently, most studies have only investigated the transition mechanism of surface wettability after laser irradiation with elapsed time. It is already known that the laser-textured copper surface experiences a wettability transition from hydrophilicity to hydrophobicity due to the occurrence of partial deoxidation from CuO to Cu₂O. This study investigates the surface wettability change of ultrafast (of the order of picoseconds) laser-textured copper surfaces treated with water baths of 50 °C and 100 °C. The pulse duration of the laser is 7 ps, the wavelength of the laser is 532 nm, and the fluence range is controlled at 1.27-2.97 J/cm². This simple treatment changes laser-textured surfaces from hydrophobic to hydrophilic ones. Detailed surface chemical analyses revealed that the formation of Cu(OH)₂ on top of the copper surfaces was attributed to the change in wettability.