Fluorine-Free and Waterborne: A Sustainable Polyurethane Coating Strategy for Superhydrophobic and Anti-Graffiti Fabrics

Liquid-like surfaces are constructed by anchoring flexible polymer chains with low glass-transition temperature onto solid substrates, imparting low liquid adhesion and easy sliding. Despite their considerable promise in anti-fouling and anti-adhesion applications, such surfaces have thus far been mainly demonstrated on smooth planar substrates. In this work, we report a waterborne polyurethane superhydrophobic fabric coating that features a liquid-like surface behavior and anti-graffiti functionality. The coating was prepared by incorporating dihydroxy single-end-terminated polydimethylsiloxane (PDMS) into polyurethane backbone, which not only reduces the surface energy of the resulting coating but also allows the formation of PDMS brushes at the coating interface, owing to the orientation and enrichment of PDMS moieties at the surface upon coating formation. The as-prepared coating on cotton and polyester fabrics exhibited static WCAs of 158.4° and 157.3°, with WSAs of 9.1° and 7.9°, respectively. Moreover, the coated fabrics demonstrate excellent anti-graffiti performance and self-cleaning ability. Mechanical durability tests revealed that the coating retained a static WCA of approximately 150° even after 20 laundering cycles or 50 abrasion cycles. Given its waterborne and fluorine-free nature, this strategy offers a feasible pathway to extend liquid-like surfaces from smooth substrates to textile substrates for practical anti-graffiti and self-cleaning applications.