LAUSR

Polymers functionalized with quaternary ammonium centers hold great promise for the development of universal ion-conducting membranes, enabling their application in energy conversion and storage technologies such as fuel cells, flow batteries, electrolyzers, etc. In this context, poly(arylene ether) polymer backbones with covalently attached quaternary ammonium moieties (e.g., imidazolium, piperidinium, guanidinium, pyrrolidinium, etc.) are utilized for the fabrication of such membranes. In this work, the strategy to the synthesis of the quaternary ammonium functionalized fluorinated poly(arylene ether) copolymers is proposed. The copolymers are synthesized by aromatic nucleophilic substitution reaction from decafluorobiphenyl and piperidinе- or morpholine-based dihydroxyl-substituted monomers using resorcinol as comonomer in both cases. Quaternized polymers with piperidinium (QFPAE-PP) and morpholinium (QFPAE-MP) side groups were synthesized via Menshutkin reactions with iodomethane in dimethylacetamide (DMAc) at room temperature. Free-standing films with a tensile strength of approximately 30 MPa were obtained from DMAc solutions of the quaternized polymers. The thermal properties of the quaternized polymers in the I⁻ form were studied using differential scanning calorimetry and thermogravimetric analysis. It was found that QFPAE-PP copolymer (and possibly QFPAE-MP) exhibits dual glass transition temperatures, which is attributed to their copolymeric nature, leading to the formation of phases enriched and depleted in cationic centers. The polymer with piperidinium groups (QFPAE-PP) demonstrated higher thermal stability, with a 5% weight loss occurring at 220 °C, compared to 200 °C for QFPAE-MP. Treatment of the quaternized polymers (QFPAE-PP and QFPAE-MP) with an aqueous alkaline solution resulted in the formation of polymeric ammonium bases (polymers in the OH⁻ form). The obtained IEC values indicate the potential of these systems for use as anion-exchange membranes in various applications.