Greener Solutions to Achieve Durable Water Repellency Without Using PFASs

This chapter explores achieving durable water repellent (DWR) coatings on textiles without the use of perfluoroalkyl and polyfluoroalkyl substances (PFASs). This was a challenge posed by W. L. Gore and Associates to the Greener Solutions Course project team at the University of California (UC) Berkeley. Ideally, a non-PFAS DWR coating would be highly hydrophobic to achieve dynamic water repellency; exhibit oil-repelling (oleophobic) properties for self-cleaning and insulation; and be durable, washable, and aesthetically pleasing to consumers. Inspiration for non-fluorinated, bio-inspired solutions was drawn from the natural hydrophobic mechanism of micro- and nano-hierarchical structuring of the lotus leaf as well as other organisms. The project team performed a literature review specific for hierarchical structuring using low hazard fibers and solvents, resulting in numerous potential alternatives. The two most promising solutions were silica nanosols and blow spinning, which showed the best hydrophobicity, potential for oleophobicity, and applicability to textiles. This chapter also highlights the mechanics of water- and oil-repellency of the possible DWR alternatives, potential hazards, and recommendations made by the project team based on these findings.