Beyond PFAS: Fluorine-free materials for sustainable high-performance surface and barrier materials

Per- and polyfluoroalkyl substances (PFAS) have long enabled high-performance surface and barrier materials due to their exceptional chemical stability, durability, and ultra-low surface energy arising from the carbon–fluorine bond. However, their environmental persistence, global distribution, and associations with adverse health outcomes have accelerated regulatory action and intensified the search for safer alternatives. Replacing PFAS while maintaining critical functionalities, such as water and oil repellency, chemical resistance, and long-term durability, remains a central challenge in materials science. This review integrates regulatory drivers with structure -property relationships to critically evaluate emerging fluorine-free strategies for coatings and barrier applications. We examine key classes of non-fluorinated polymers, bio-based materials, and hybrid composite systems, highlighting how performance is achieved through complementary mechanisms including surface energy modulation, pore sealing, diffusion tortuosity introduced by high-aspect-ratio fillers, hierarchical surface structuring, and composite architectures. Rather than relying solely on ultralow surface energy, many PFAS-free systems achieve functional performance through geometry-enabled transport control and synergistic material design. Comparative analysis reveals that while no single fluorine-free material universally replicates PFAS performance, application-specific designs can deliver competitive water and oil resistance, barrier properties, and mechanical integrity. Remaining challenges include durability under real-world conditions, scalability within existing manufacturing infrastructure, and comprehensive life-cycle and toxicological assessment to avoid regrettable substitutions. By synthesizing advances across polymer chemistry, surface engineering, and sustainable materials design, this review outlines mechanistically informed pathways toward scalable, high-performance, and environmentally responsible alternatives to PFAS for next-generation surface and barrier technologies.