Non-Fluorinated Functional Polyolefin for Puncture-Resistant and Self-Healable Proton Exchange Membranes of Fuel...

The development of puncture-resistant and self-healing proton exchange membranes (PEMs) is vital for enhancing fuel cells' (FCs) durability and safety; however, it remains a formidable challenge. Herein, we report a non-fluorinated polyolefin-based PEM that integrates autonomous self-healing, puncture resistance, high gas barrier, and exceptional overall durability in FC applications. The polymers are prepared through rare-earth-catalyzed selective polymerization of isoprene, partial hydrogenation, thiol-ene click chemistry, and oxidation, yielding a sulfonic acid-functionalized polyolefin. The main chain structure of polymers features rigid poly(3-methyl-1-butene) segments-derived from 3,4-polyisoprene units-and soft ethylene-alt-propylene sequences-originating from cis-1,4-polyisoprene units. The nanoscale microphase separation between these hard and soft segments provides exceptional mechanical robustness and self-healing capability, while the aggregation of sulfonic acid groups creates efficient proton transport pathways. The resulting membrane achieves high through-plane proton conductivity of 1.0 × 10^{- 2} S cm^{- 1} and in-plane conductivity of 6.4 × 10^{- 1} S cm^{- 1} at 80°C and 100% RH. Under simulated FC operating conditions, the material autonomously heals mechanical damage, fully recovering its tensile strength, proton conductivity, gas barrier properties, and FC performance. This work establishes a versatile strategy for creating high-performance, non-fluorinated PEMs with enhanced safety and prolonged service life.