含二氮杂萘酮基的磺化聚芳砜氧膦质子交换膜的制备与表征

From the viewpoint of molecular design, two kinds of chemical units are incorporated to the backbone of the same polymer, which facilitate the polymer to have excellent resistance to swelling and oxidation, respectively. Thus the aromatic proton exchange membranes with low swelling, high oxidative stability and other excellent properties could be achieved. 4-(4-Mercaptophenyl) phthalazinone (MPPZ) and three kinds of sulfonated bis(4-fluorophenyl)phenyl phosphine oxide monomers are initially designed and then synthesized. MPPZ and bis(4-fluorophenyl)phenyl phosphine oxide could polycondensated with the above sulfonated monomers, the phthalazinone, thioether and phosphine oxide groups thus were introduced to the products, i.e., sulfonated poly(arylene thioether phthalazinone)s bearing phthalazinone units. Their sulfonation degree could be adjusted by the ratios of the feed in order to control the properties of products. Among them, the products with best overall properties were oxidized to sulfonated poly(arylene sulfone phthalazinone)s bearing phthalazinone units. The sulfone groups derived from thethioether groups could deactivate the benzene rings connected with themselves, greatly improving the oxidative stability of products. The phthalazinone units, which show excellent oxidative resistance, could form strong hydrogen-bonds with the protons of sulfonic acid groups, hence reducing the swelling of products to a large extent. The sulfonic acid groups locate in the pendant benzene rings. This is favorable to improve the oxidative stability of membranes. In addition, the hydropholic/hydrophobic block sulfonated poly(arylene sulfone phthalazinone)s membranes and the polybenzimidazole blend membranes are also prepared so as to further improve the overall properties.

从分子设计着手，将具有耐溶胀和耐氧化的两种结构单元裁剪到同一聚合物结构中，制备耐溶胀耐氧化性、综合性能优良的芳香族聚合物质子交换膜。首先设计并合成4-(4-巯基苯基)二氮杂萘酮（MPPZ）和三种磺化二（4-氟苯基）苯基氧膦单体。将其与二（4-氟苯基）苯基氧膦单体共聚，从而把二氮杂萘酮基、硫醚和氧膦基团引入到同一聚合物结构中，并通过反应物配比来调节产物磺化度，以调节聚合产物的性能。筛选出综合性能较好的产物，将其氧化得到含二氮杂萘酮基的磺化聚芳砜氧膦。其间，硫醚被氧化成砜基，钝化了与之相连的苯环，大幅提高耐氧化性能。二氮杂萘酮基团耐氧化性能好，并且还能与磺酸质子形成强烈的氢键缔合，大幅降低产物溶胀率。因磺酸基团位于侧基苯环上，可望改善膜的耐氧化性能。此外，还制备亲水/疏水嵌段的和用磺化聚苯并咪唑共混的磺化聚芳砜氧膦基质子交换膜，进一步改善膜的综合性能。

本组率先开发了磺化聚芳(硫)醚氧膦质子交换膜，具有潜在的应用前景，但部分膜也存在当电导率较高时溶胀率偏大的普遍问题。并且，至今也没有关于芳香族质子交换膜在实际应用条件下具有足够使用寿命的报道。而耐溶胀性和耐氧化性与电导率又是相互制约的。因此优化并提高这三个主要性能是芳香族质子交换膜的关键问题。. 针对这一目标，本项目采用分子设计的方法，合成了一系列单磺化、双磺化、三磺化的聚芳醚氧膦膜和聚芳硫醚氧膦膜。对比研究表明，磺酸基的分布方式对这些膜的离子通道尺寸与连通性有重大影响。当磺化度相同时，二磺化聚芳醚氧膦与单磺化聚芳醚氧膦相比，离子通道尺寸略增大，连通性变差；三磺化聚芳醚氧膦与二磺化聚芳醚氧膦相比，离子通道尺寸急剧增大，连通性显著变下降。而从单磺化到二磺化，再到三磺化聚芳醚氧膦膜，其疏水相的尺寸和连通性均增大。因此，当磺化度相等时，从单磺化到二磺化，再到三磺化聚芳醚氧膦膜，耐溶胀性显著增加，耐氧化性大幅提高，电导率下降。另一方面，对于磺酸基分布方式相同的膜，随着磺化度的增加，其离子通道尺寸增大，连通性增加，电导率增大。因此，综合调节磺酸基分布方式和磺化度，能形成特殊的微相分离结构，从而实现了同时提高磺化聚芳醚氧膦膜的耐溶胀性、耐氧化性和电导率，大幅提高了综合性能。该方法也适用于磺化聚芳硫醚氧膦质子交换膜，具有较为普遍的意义。三磺化聚芳醚氧膦质子交换膜综合性能优异，其耐氧化性能是目前芳香族质子交换膜中最好的，有巨大应用前景。本项目的成果可以认为是质子交换膜研究领域的重大突破。