Current military and industrial textiles and uniforms fields use per- and polyfluoroalkyl substances (PFAS) treatment technologies to achieve omniphobic property. The overarching objective of this project is to develop lignin-based and fluorocarbon-free coatings that can impart omniphobicity to various textile materials (e.g., natural and synthetic fibers), paralleling the liquid-repellency of PFAS-based coatings. The project team hypothesizes that combining fluorocarbon-free lignin derivatives with the low solid surface energy and inherent re-entrant texture (i.e., overhang or convex texture) of commercial fabrics can lead to sustainable and robust omniphobic coatings for military textiles and uniforms, as well as broad textile applications.

This project will use lignin (a plant-derived biomaterial) to fabricate fluorocarbon-free omniphobic textile coatings employing integrated experimental and theoretical approaches. The project team will first synthesize lignin derivatives with low surface energy by introducing a linear long chain hydrocarbon segment onto lignin. The omniphobic coatings will be fabricated by spraying such materials onto military-relevant fabrics (e.g., natural cotton and synthetic nylon fabrics). Secondly, innovative spherical lignin-based nanoparticles (LNP) will be synthesized, stabilized, and modified to further enhance the omniphobicity of the coatings through the formation of hierarchical surface texture. Further, the durability of omniphobic coatings will be improved using an LNP-epoxy mixture resulting in the formation of ether bonds and a mechanical interlocking network with the fabric fibers. Various characterization techniques (e.g., contact angle measurements, oil-repellency tests, etc.) will be used to evaluate coating performance (e.g., omniphobicity, durability, thermal resistance, etc.). Lastly, a preliminary sustainability model will be established based on laboratory findings to guide the design of sustainable omniphobic textile coatings.

The sustainable materials and coating technology – aqueous-based, scalable, and durable, will have no detrimental effect on the fabrics or the environment. Successful completion of this project will provide innovative and omniphobic military-relevant fabric prototypes. The technology will also be ground-breaking to transform the current PFAS-dominated omniphobic coatings into sustainable coatings, which could mitigate the potential impacts of PFAS on the ecosystem and human health.