基于聚苯并咪唑/超支化聚合物的交联共混体系的高温质子交换膜

High-temperature Proton Exchange Membranes Based on Cross-linked Polybenzimidazole/hyperbranched-polymer Blends

在可溶性高分子量芳醚型聚苯并咪唑(OPBI)基体中引入超支化聚对氯甲基苯乙烯(H-VBC),通过便捷的溶液共混-浇铸法,制备了基于聚苯并咪唑/超支化聚合物的新型交联体系(OPBI/H-VBC-1和OPBI/H-VBC-2),并对膜进行季铵盐化处理(OPBI/H-VBC-QA-1和OPBI/H-VBC-QA-2),实现了复合膜综合性能的提升.与原始OPBI膜相比,交联型复合膜表现出优异的尺寸稳定性和"抗塑化"能力.在85%磷酸中浸泡72 h后,OPBI/H-VBC-2和OPBI/H-VBC-QA-2的体积膨胀率只有184.2%和152.4%,而OPBI的体积膨胀率达到336.5%;OPBI/H-VBC-2和OPBI/H-VBC-QA-2的最大拉伸强度分别达到36.3和21.9 MPa,比单一OPBI膜的10.9 MPa提高了56%-233%.研究发现,季铵盐化的复合膜具有更高的质子传导率(在200℃下的质子传导率分别达到151.5和103.4 mS/cm)与磷酸吸收水平比值.对比研究发现,所制备的交联型复合膜比已报道大多数高温质子交换膜(HT-PEM)具有更优异的质子传导率与力学强度平衡能力.

In this study,we introduced a hyperbranched poly(p-chloromethylstyrene)(H-VBC)into a soluble high-molecular weight arylether-type polybenzimidazole(OPBI)matrix,and a new type of cross-linking system(OPBI/H-VBC-1 and OPBI/H-VBC-2)based on polybenzimidazole/hyperbranched polymer was obtained through the convenient solution blending-membrane casting preparation process. Finally,the comprehensive performance of the blend membranes was greatly improved. In comparison to the pristine OPBI membrane,the cross-linked blend membranes had more excellent dimensional stability and resistance to plasticization. After soaking in 85% phosphoric acid for 72 h,the volume swelling ratios of OPBI/H-VBC-2 and OPBI/HVBC-QA-2(the quaternized membrane)were only 184.2% and 152.4%,respectively;while the swelling ratio of OPBI reached 336.5%. The maximum tensile strengths of OPBI/H-VBC-2 and OPBI/H-VBC-QA-2 reached36.3 and 21.9 MPa,respectively,which were 56%—233% higher than the 10.9 MPa of OPBI membrane. We also found that the quaternized membranes had a higher ratio of proton conductivity to phosphoric acid absorption level than corresponding unquaternized ones. At 200 ℃,the proton conductivities of the quaternized composite membrane reached 151.5 and 103.4 mS/cm,respectively. Further,a comparative study showed that the quaternized cross-linked blend membranes had a better balance ability of proton conductivity and mechanical strength than most of the reported high-temperature proton exchange membranes(HT-PEMs).