Robust PFAS-Free Superhydrophobicity Exhibited in Hierarchically Nanostructured Coatings on Textiles

Abstract

Long chain per- and polyfluorinated chemical compounds, commonly referred to as PFAS, historically offered superior breathable and flexible water-repellent textile finishes on clothing. Now notoriously deemed “forever chemicals” for their environmental persistence and ability to bioaccumulate, they can cause a range of human health impacts including cancer and reproductive harm, which has highlighted the need for less harmful but equally superhydrophobic coatings. Inspired by the microscopically bumpy water-repellent surfaces of lotus leaves, this work introduces a PFAS-free hierarchical nanocoating on and within textile substrates using a multistep synthetic approach, involving fabric pretreatment to facilitate a robust particle-to-substrate attachment of subsequently infiltrated silica nanoparticles (NPs), followed by surface functionalization of textile-infiltrated NPs with long-alkyl-chain silanes to impart PFAS-free water repellency. The system is subjected to rigorous wash testing and found consistent superhydrophobic performance after 65 wash cycles. Furthermore, the system can be adapted as a flexible platform technology for a variety of design opportunities by changing the substrate, NP composition, and surface chemistry to suit a variety of applications. Herein, a robust, flexible, and breathable interface between fabric and water that offers a next-generation PFAS-free water-repellent textile coating solution is developed.