Recent Advances in Fluorinated Polymeric Membranes for Helium Separation from Natural Gas: Innovations and Challenges

Fluorinated polymers have garnered prominence in membrane-based helium extraction. This review comprehensively examines recent advances in fluorine-containing polymeric helium separation membranes, covering fluorinated polyimide, perfluorinated polymers, and postfluorinated membranes. This review explores fluorination as a promising strategy in membrane design, demonstrating its unique role in concurrently optimizing the diffusivity and solubility selectivity to unlock new frontiers in helium separation. Fluorine introduction induces well-defined hierarchical free volume distributions while creating ultramicroporosity that preferentially facilitate helium transport. Fluorination also dramatically improves He solubility selectivity by suppressing the solubility of larger gases while preserving helium solubility. The review further critically evaluates key technical challenges, including industrial stability, plasticization resistance, and scalability while identifying emerging opportunities in fluoropolymer design, modification routes, and hybrid membranes. Ultimately, it aims to establish a crucial roadmap offering fundamental insights and practical guidance for next-generation fluorinated membranes, which is essential to mitigating the global He shortage.