Wettability of the Cotton and Polyester Fabrics Coated by Nanostructured Indium-doped Zinc Oxide Layers.

Indium-doped zinc oxide (ZnO:In) thin films were deposited onto cotton (Ct) and polyester (PET) fabrics via Successive Ionic Layer Adsorption and Reaction (SILAR) method for the purpose of developing comfortable to wear, nontoxic, lightweight, and air-permeable textile. Thus, we obtained materials with hierarchical micro- and nanoscale roughness ZnO:In/Ct and ZnO:In/PET, respectively. The obtained ZnO:In films have a single-phase nanograined polycrystalline wurtzite hexagonal structure. It has been shown that the inherent cotton hydrophilicity provides wettability of ZnO:In/Ct fabric both before and after vacuum annealing. On the contrary, the ZnO:In/PET fabric is hydrophobic, its water contact angle CA equals 140°. It turned out that it is possible to impart superhydrophobic properties to the ZnO:In/PET fabric without any additional impregnation layer by means of post-growth vacuum annealing at 200 °C for 1 or 2 h. The superhydrophobiсity of this fabric was confirmed via both static and dynamic measurements of CA = 160° and contact angle hysteresis CAH = 10°, respectively. The Cassie-Baxter wetting state for the annealed ZnO:In/PET fabric is identified through a water-drop evaporation technique. Upon exposure to ultraviolet (UV) radiation (26 W, wavelengths in the 315-400 nm range) for 60 min, the vacuum annealed ZnO:In/PET fabrics are transformed from superhydrophobic to hydrophobic, their СAs reduced from 160° to ~ 130° and returned after 9 days of storage in the dark. Thus, we obtained a superhydrophobic fabric that remains non-wettable under operating conditions in sunlight. [ABSTRACT FROM AUTHOR]