Valorisation of phosphine tail gas into phosphorus-containing single-ion conducting polymers with high hydrolytic stability and potential recyclability

Value-added utilisation of industrial and agricultural residues is an attractive strategy to address resource shortages and promote greener chemical production. PH 3 , a hazardous by-product of hypophosphite preparation, requires careful handling due to its high toxicity and flammability. In this study, we developed a method to convert PH 3 tail gas into hydrolytically stable single-ion conducting polymers (SICPs) with potential recyclability after service. Oligoether-containing styrenic monomers (VBP-nEO) were synthesised from 4-vinylbenzyl(bis(hydromethyl))phosphine oxide (VBzHPO) via Williamson etherification in water, and the resulting functional monomers underwent conventional free-radical polymerisation to produce both homo- and co-polymers. The water-soluble homopolymers exhibited high hydrolysis resistance under both acidic and basic conditions because the phosphorus atom was covalently bonded to three substituents through P–C bonds. The co-polymers containing dissociable lithium salt segments exhibited promising ionic conductivity at moderate temperatures (4.48 × 10 −6 S/cm at 90 °C), which depended on the ethylene oxide (EO) content and EO/Li + ratio within the co-polymers. All co-polymers showed high thermal stability, with initial decomposition temperatures exceeding 300 °C and calculated LOI values above 21 %.