Comparison of PEM properties of copoly(aryl ether ether nitrile)s containing sulfonic acid bonded to naphthalene in structurally different ways

The study represents a comparative investigation of three series of high molecular weight aromatic poly(aryl ether ether nitrile) copolymers (SPAEEN-n), containing different sulfonated naphthalene groups, where n (in the range 0-80 mol %) refers to molar percentage of repeat units containing the sulfonic acid function. The three series of SPAEEN-n copolymers were synthesized via potassium carbonate-mediated nucleophilic polycondensation reactions of commercially available monomers: 2,6-difluorobenzonitrile (2,6-BFBN), one of three dihydroxynaphthalenesulfonate (DHNS) monomers, and unsulfonated 4,4'-biphenol (BP), incorporated for the purpose of adjusting the sulfonic acid content. The incorporation of the sulfonated repeat unit into copolymers and their structures were confirmed by H-1 NMR and FT-IR spectroscopy. Products were solvent-cast into membranes of varying ionic content as proton exchange membrane (PEM) materials for fuel cells applications. Ion exchange capacity (IEC), thermal stabilities, swelling, and proton conducting properties of the membranes were investigated in relation to their structures and compared with those of perfluorinated ionomer (Nafion 117). Films of SPAEENH copolymers in acid form all showed high thermal stabilities with glass transition temperatures (T-g) > 224 degrees C and decomposition temperatures (T-d) > 264 degrees C. In general, the SPAEENH copolymers exhibited low moisture absorption and in some instances high proton conductivities (from 10(-2) to 10(-1) S/cm) comparable to that of Nafion 117 at similar water uptake, swelling, and H2O/SO3H ratio.

本研究对三个系列含有不同磺化萘基团的高分子量芳香族聚（芳醚醚腈）共聚物（SPAEEN - n）进行了比较研究，其中n（在0 - 80 mol%范围内）是指含磺酸官能团的重复单元的摩尔百分比。这三个系列的SPAEEN - n共聚物是通过碳酸钾介导的市售单体的亲核缩聚反应合成的：2,6 - 二氟苯腈（2,6 - BFBN）、三种二羟基萘磺酸盐（DHNS）单体中的一种以及未磺化的4,4'-联苯酚（BP），加入BP是为了调节磺酸含量。通过H - 1 NMR和FT - IR光谱证实了磺化重复单元被引入共聚物及其结构。产物通过溶剂浇铸制成具有不同离子含量的膜，作为用于燃料电池应用的质子交换膜（PEM）材料。研究了膜的离子交换容量（IEC）、热稳定性、溶胀和质子传导性能与其结构的关系，并与全氟离聚物（Nafion 117）进行了比较。酸形式的SPAEENH共聚物薄膜都显示出高的热稳定性，玻璃化转变温度（T - g）> 224℃，分解温度（T - d）> 264℃。一般来说，SPAEENH共聚物表现出低吸湿性，在某些情况下具有与Nafion 117在相似的吸水率、溶胀率和H₂O/SO₃H比时相当的高质子电导率（从10⁻²到10⁻¹ S/cm）。