Sustainable design of non-fluorinated yet oleophobic fibrous surfaces

Abstract

Surfaces repellent towards oils and other low surface tension fluids have a wide range of applications, particularly in the textile space, for example in outdoor apparel, protective clothing, and home furnishings. Per- and polyfluoroalkyl substances (PFAS) are commonly used to provide low surface energy to textile finishes. However, this class of chemicals is either banned or being phased-out worldwide, due to environmental and health concerns. Here, we develop a liquidlike polymer-brush-based polydimethylsiloxane (PDMS) finish that is simple to apply to fibrous surfaces like fabrics, enabling them to repel ultra-low surface tension liquids such as ethanol (γ_LV = 22.3 mN m⁻¹). In addition, we determine the accuracy of current wettability theory in predicting the resultant wettability of such PFAS-free oleophobic surfaces, to understand which design parameters remain applicable to textured surfaces treated with these sustainable, low surface energy chemistries. Our findings reveal that one-dimensional wettability theory offers a more accurate prediction of the wetting properties for balanced twill weave monofilament metal meshes and plain weave multifilament fabrics but lacks predictive power for more complex geometries, such as warp faced twill weave meshes and knit fabrics. Furthermore, we find that yarn spacing plays a more dominant role than yarn radius in achieving a robust non-wetted interface. Overall, the finish developed here represents a potential alternate surface chemistry for achieving low surface tension fluid repellency, and the design principles of such a finish enable the realization of sustainable oleophobic or even superoleophobic surfaces.