Sonochemical Coating of Textiles with Zinc Oxide: Robust, Silver-Seeded Growth on Cotton for Effective UV Shielding

We report on the in situ silver-seeded generation and growth of pure wurtzite zinc oxide (ZnO) onto woven cotton fabric substrates via sonochemical deposition. Coating leaching issues and limitations related to processing temperature often restrict the direct application of crystalline metal oxides onto soft matter substrates under ambient conditions. Herein, we describe a mechanochemical synthesis route that allows for the direct generation and durable incorporation of crystalline metal and metal oxide materials onto polymeric substrates, at high loading, without the use of binders, annealing steps, low-vacuum processing, or any other conventionally encountered processing procedures. The model system of Ag-seeded, ZnO on woven cotton textile fabrics presented here demonstrates this efficacy while further doping of the system with Fe allows for the ZnO coating optical properties to be readily tuned. Samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis transmittance-reflectance spectroscopy, inductively coupled plasma optical emission spectroscopy, as well as air permeability and tensile testing. While the results for this model system show excellent crystallinity, attachment durability/washfastness, and tunable optical parameters, this synthesis method also offers broader routes to the ready incorporation of textured crystalline metal, metal oxide, and other systems into low-temperature stable, soft matter substrates. For the illustrative application of UV-blocking capability, the coated substrates output consistently high UV-protection factor values (>UPF50), even after 51 wash laundering cycles, and with near-complete suppression of UV-A and UV-B radiation.