Superhydrophobic cotton fabrics based on ZnO nanoparticles functionalization

In the present work, 100% cotton knitted fabrics were functionalized with ZnO nanoparticles, in order to enhance the hydrophobic properties of the fibers surface. The incorporation methods of ZnO NPs and different types of cotton samples (including polymer coated, and uncoated with and without a nonionic pretreatment) were evaluated, in order to understand the influence in the hydrophobicity values. Cotton fabrics with and without NPs were characterized by ground-state diffuse reflectance, field emission scanning electron microscopy and energy-dispersive spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy and water contact angle (WCA). The best results were obtained when the polymer-coated fabric was functionalized using a precursor concentration of 0.2 M, exhibiting superhydrophobic behavior with static WACs of more than 150 degrees. Although pretreated and untreated ZnO-functionalized cotton fabrics had a slightly lower wettability, they showed interesting results, with improvements in WCA from 116 degrees to 143 degrees. In summary, this work demonstrates that the ZnO NPs have a huge potential to be used as surface finishings for the development of easy cleaning fibrous structures.