Rational design of multi-layered superhydrophobic coating on cotton fabrics for UV shielding, self-cleaning and oil-water separation

It remains a great challenge to prepare multi-functional fabrics using a low-cost and scalable method with fluorine-free materials. In this paper, we report a new procedure for producing fluorine-free super hydrophobic cotton fabrics, via a simple dip-coating process. Firstly, a polydimethylsiloxane (PDMS) adhesive layer is deposited onto the cotton substrate, followed by the subsequent deposition of ZnO nanoparticles to enhance the surface roughness through an oil bath process. Finally, a second PDMS dip-coating is applied to construct a multilayered PDMS-ZnO-PDMS composite coating on the cotton fabrics. The multi-layer coated samples display superhydrophobic properties, with a water contact angle (CA) exceeding 160 degrees. Additionally, the new PDMS-ZnO-PDMS@cotton fabric exhibits excellent multi-functions, including UV-blocking, self-cleaning and oil-water separation. The prepared superhydrophobic fabric can withstand a large number of abrasion cycles and 20 cycles of accelerated washing without obvious decline in the water contact angle. This facile preparation method is of low-cost, environmentally friendly, and suitable for large-scale production of a series of specialty fabrics including sports clothing. (C) 2017 Elsevier Ltd. All rights reserved.