A fluorine-free method for fabricating multifunctional durable superhydrophobic fabrics

In this study, fly ash (FA), which is a waste product of common flue gas, was used to effectively fabricate multifunctional superhydrophobic surfaces. FA was first coated with a TiO 2 shell layer to form a core (FA)-shell (TiO 2 ) structure via charge adsorption. FA-TiO 2 was then grafted with polydimethylsiloxane (PDMS) molecules to form FA-TiO 2 -PDMS particles, which exhibited superhydrophobicity. The PDMS molecules were grafted firmly on the TiO 2 shell through covalent bonds, therefore endowing the particles a series of durable properties. The superhydrophobic FA-TiO 2 -PDMS particles mixed with PDMS could form homogenous coating solution, which was coated onto fabrics to obtain superhydrophobic surfaces. The resulting superhydrophobic fabric exhibited the “Lotus-effect” and excellent self-cleaning ability. It also showed excellent photocatalysis ability that could repeatedly photodegrade various oils and dyes. Moreover, the coated fabric showed durable and stable superhydrophobicity, which could withstand repeated abrasion treatments, recycled peeled tests using an adhesive tape, long-duration boiling-water immersion, and recycled solvent immersion. In addition, the surface exhibited strong self-healed superhydrophobicity after a simple heat treatment even after being repeatedly treated by plasma or immersed into a strong alkali/acid solution for 8 h. The superhydrophobic fabrics also achieved self-quenched fire-retardance and could efficiently separate various oil-water mixtures.