Synthesis and Properties of Branched-Crosslinked Poly(aryl piperidinium) Anion Exchange Membranes

Abstract

As a promising sustainable energy conversion technology, anion exchange membrane fuel cells (AEMFCs) have attracted substantial research attention due to their eco-friendly characteristics, cost advantages, and potential for high efficiency. The advancement of these systems, however, remains fundamentally limited by the challenge of optimizing the critical trade-off between ionic conductivity and dimensional stability in anion exchange membranes (AEMs). This investigation proposes a novel membrane architecture combining ether-free polymer matrices with piperidinium cationic moieties to address chemical durability concerns. A series of cross-linked poly(p-triphenylpyridine) membranes were successfully fabricated through optimized Friedel-Crafts alkylation processes, incorporating pyridine-derived branching structures alongside conventional quaternary ammonium cross-linkers. The optimized QAPTTP-40% membrane exhibits outstanding electrochemical properties, achieving temperature-enhanced ionic conductivity of 116.2 mS cm⁻¹ at 80 °C through cooperative effects of branched morphology and cross-linked framework. Extended alkaline stability testing (15 days in 2 M NaOH at 80 °C) revealed exceptional chemical resilience with 85.1% conductivity retention. Structural characterization demonstrated advantageous material properties including an elevated ion exchange capacity of 2.94 mmol g⁻¹ coupled with robust mechanical strength (39.4 MPa tensile strength at ambient conditions). The synergistic combination of efficient ion transport pathways, superior alkaline durability, and mechanical robustness establishes this innovative AEM design as a competitive platform for next-generation fuel cell development. These findings provide critical insights into the rational design of high-performance anion exchange membranes through molecular engineering of polymer architectures and cationic group selection.