Near infrared laser-mediated hydrophilicity-to-hydrophobicity switch of copper sulfide nanoflowers coating on cotton fabric

To our knowledge, surface hydrophobicity is normally fabricated by hydrophobic or fluorinated materials; however, it can be predicted. So, it is exciting and high value that using a single hydrophilic material directly obtains a hydrophobic surface , which may be a promising and significant aspect and a great challenge in surface and interface science . Herein, the copper sulfide (CuS) nanoflowers were in-situ deposited on the cotton fabric after cotton fabric was incubated with copper(II) chloride dihydrate and thioacetamide stirring for 3 h at 80 °C, labelled as Cot@PTA@CuS. Then, Cot@PTA@CuS was treated by near infrared (NIR) laser irradiation at 808 nm, recorded as Cot@PTA@CuS-NIR. Interestingly, Cot@PTA@CuS-NIR exhibits good hydrophobicity with WCAs of 136.5 ± 3.5° and hydrophobic stability within 30 min. Notably, the hydrophobicity of Cot@PTA@CuS-NIR is created without using the lower surface free energy materials, possessing significant progressiveness compared with conventional surface hydrophobicity fabricated by hydrophobic or fluorinated materials. The X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) demonstrate the formation of cuprous oxide (Cu 2 O) after NIR laser irradiation. Subsequently, the polydimethylsiloxane (PDMS) was selected to encapsulate CuS nanoflowers with improving the stability of CuS nanoflowers and obtaining superhydrophobicity, recorded as Cot@PTA@CuS-NIR@PDMS, achieving the results of killing two birds with one stone. Cot@PTA@CuS-NIR@PDMS also has an excellent photothermal effect and UV resistance. Finally, Cot@PTA@CuS-NIR@PDMS was used for efficient oil/water separation. Overall, this work renders a novel, feasible, and facile idea for gaining surface hydrophobicity by hydrophilic CuS nanoflowers with NIR laser irradiation, inspiring more scholars to create surface hydrophobicity by hydrophilic materials.