Near infrared laser precisely controlled ultrafast superhydrophilicity-to-hydrophobicity transition of copper sulfide nanosphere coating on cellulose fiber fabric.

Inspired by lotus leaf, biomimetic hydrophobic cellulose fiber-based textiles were usually fabricated by the lower surface energy materials. However, it is rare to witness a hydrophobic surface obtained by near infrared laser (NIR) irradiation a superhydrophilic nanomaterial, which remains a huge challenge. Herein, the CuS nanospheres was in-situ anchored on the surface of gallic acid self-polymer treated cotton fabric. Luckily, the excellent hydrophobicity of CuS nanospheres coating (contact angles of 142.7 ± 2.8°) was for the first time demonstrated after a NIR laser irradiation with 1.5 W/cm for 8-10 s. Notably, the novel hydrophobicity exhibits a significant advance compared with traditional hydrophobicity prepared by lower surface energy materials. Then, the laser-mediated hydrophobic mechanism was demonstrated by the cold-field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermal imager. Moreover, the dynamic contact angle revealed the uniform hydrophobicity. Furthermore, the hydrophobic nanospheres coating possessed good photothermal effect and UV resistance. Overall, this work renders a novel, feasible, and efficient strategy to rapidly obtain the hydrophobic surface by NIR laser-induced the superhydrophilic CuS nanospheres coating.