Fluorine-Free Biobased Polyurethane Coatings for Durable Superhydrophobic Textiles

The development of fluorine-free, sustainable, and durable water-repellent coatings is significant for the textile industry but remains a challenge. In this work, we report a biobased polyurethane with a well-balanced rigid-flexible architecture. The rigid segments were synthesized using sorbitan tristearate and isophorone diisocyanate, while Priplast 3238, an amorphous biopolyester diol, was introduced to enhance the molecular flexibility. Subsequently, the polyurethane emulsion was applied to cotton, polyester, and nylon fabrics using a dip–pad–cure process, resulting in superhydrophobic coatings. The treated cotton and polyester fabrics exhibited water contact angles exceeding 150°, while the nylon reached 140°. In addition, the coated cotton fabric maintained excellent hydrophobicity after 3000 mechanical cycles, 600 sandpaper abrasions, 10 laundering cycles, and 70 h of immersion in various pH solutions and chemical solvents. Importantly, all treated fabrics retained desirable air permeability, softness, and tensile strength. In summary, this study provides insights into biobased water-repellent systems for broad industrial applications.