A green urethane coating for mechanically durable superhydrophobic fabric

Developing fluorine-free, bio-based, and mechanically robust water repellent coating is attractive for the textile industry, yet remains challenging. In this work, we reported a bio-based urethane prepared in one step by utilizing the nucleophilic addition reaction between sorbitan tristearate and isophorone diisocyanate. The obtained urethane was subsequently emulsified and applied onto three types of fabrics including cotton, polyester pongee, and nylon taffeta through a simple dip-pad-cure process, to produce durable superhydrophobic coatings. Both the resulting cotton fabrics and polyester fabrics exhibit static water contact angles above 150° and a grade of 5 in the water spray test, while the nylon fabrics own a water contact angle of 147° and a grade of 4 in the water spray test. All the fabrics maintained excellent air permeability. Besides, the treated fabrics maintain hydrophobicity after harsh durability tests, including 3000 cycles of friction, 400 cycles of sandpaper abrasion, and 70 h of chemical corrosion. Overall, the findings presented in this study offer valuable insights into the development of non-fluorine durable bio-based water repellents, highlighting their potential for diverse industrial applications. Graphical abstract