Most Troger's base (TB)-based polymers reported for high-temperature proton exchange membranes (HT-PEMs) exhibit low phosphoric acid (PA) tolerance due to excessive swelling in PA solution. In this work, a novel dicarboxylic acid monomer containing both naphthalene and TB units (TB-N-COOH) was successfully synthesized, and the corresponding TB-based PBI homopolymer (TB-N-HPBI) was prepared for HT-PEM fuel cells (HT-PEMFCs). In addition, naphthalene units were incorporated into TB-based PBI copolymers (TB-N-CoPBIs). The resulting TB-N-HPBI and TB-N-CoPBIs exhibited high molecular weight and excellent solubility in organic solvents (e.g., DMSO and NMP) because of the twisted TB units. The incorporated naphthalene units significantly improved the oxidative stability. More importantly, the existed naphthalene units in polymer backbones endowed the membranes with excellent PA tolerance capability because of the rigid structure and poor affinity to PA, which limited excessive swelling in 85 wt% PA solution and hence promoted acid uptake capability. Among of them, the TB-N-HPBI membranes showed ultrahigh PA uptake of 508.6%, and resulting in the proton conductivity of 201 mS cm at 160 °C under non-humidity conditions, which are far superior to most reported TB-based polymer membranes. In addition, the maximum peak power density (H/air) of 437.2 mW cm was achieved. Our present work demonstrated that the incorporation of the naphthalene units into TB-based PBI significantly promoted the improvement of comprehensive performance for HT-PEMFCs.

中文翻译：

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可溶性 Troger 的碱基聚苯并咪唑含有萘单元，具有改进的磷酸耐受性，可用作高温质子交换膜

据报道，大多数用于高温质子交换膜 (HT-PEM) 的 Troger 碱 (TB) 聚合物由于在 PA 溶液中过度膨胀而表现出较低的磷酸 (PA) 耐受性。在这项工作中，成功合成了一种同时含有萘和TB单元的新型二羧酸单体（TB-N-COOH），并制备了相应的TB基PBI均聚物（TB-N-HPBI）用于HT-PEM燃料电池（ HT-PEMFC）。此外，萘单元被纳入TB基PBI共聚物（TB-N-CoPBI）中。由于扭曲的TB单元，所得TB-N-HPBI和TB-N-CoPBI表现出高分子量和在有机溶剂（例如DMSO和NMP）中优异的溶解度。掺入的萘单元显着提高了氧化稳定性。更重要的是，聚合物主链中存在的萘单元由于结构刚性和与PA的亲和力差而赋予膜优异的PA耐受能力，限制了在85wt%PA溶液中的过度溶胀，从而提高了酸吸收能力。其中，TB-N-HPBI膜表现出高达508.6%的PA吸收率，在160°C、非潮湿条件下质子电导率达到201 mS cm，远远优于大多数报道的TB基聚合物膜。此外，最大峰值功率密度（H/空气）达到437.2 mW cm。我们目前的工作表明，将萘单元纳入TB基PBI中可以显着促进HT-PEMFC综合性能的提高。