【作者】 李雪峰；

【导师】 姜振华；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2011， 博士

【摘要】 针对传统磺化聚芳醚类质子交换膜材料存在传导率和机械性能难以平衡的不足之处,本文从分子结构设计角度出发,研制了两类具有优势结构的磺化聚芳醚材料。首先,考虑到传统磺化聚芳醚材料的磺酸基团酸性较弱的特点,将具有强酸性的全氟磺酸链段引入聚芳醚材料的侧链,制备类Nafion膜结构的磺化聚芳醚材料。力图通过提高磺酸酸性,在合理的磺化度范围内来提高聚合物聚芳醚聚合物的质子传导率。实验结果显示该类膜材料在低磺化度时表现出高的质子传导率。证实了依靠提高磺化聚芳醚膜材料酸性的方式来提高膜传导率的途径可行。其次,在不改变磺化聚芳醚芳香型碳氢结构的基础上,通过设计聚合物结构的方法,调整聚合物微结构的手段来提高聚合物质子传导率和力学性能。通过对聚合物疏水链段的设计,将大分子量的疏水结构通过直接共聚的方法引入聚合物主链结构,在高磺化度情况下促使聚合物疏水链段紧密堆砌形成稳固的疏水相。由此来提高材料的传导率和机械强度。实验结构显示所设计的聚合物在高温显示出非常优越的性能:传导率高于商品化的膜材料Nafion膜,且在低湿度下仍然具有较高的质子传导率。为了进一步调整材料的磺化度我们制备了含大分子量疏水链段的共聚型聚芳醚材料,并且将极性的腈基基团引入聚合物进一步提高聚合物的链段间作用,提高材料力学强度。实验结果显示我们制备含有大分子量疏水链段的聚芳醚材料在高的质子传导率情况下保持了良好的机械性能。同时材料的高温、低湿条件下表现出优越全氟磺酸膜材料和传统磺化聚芳醚材料的特性。综上,本文从聚合物结构设计出发设计、合成了两类新型聚芳醚质子交换膜材料。并对材料进行的详尽的性能评价,结果显示磺化聚芳醚材料的酸性和微相结构是影响材料性能的关键因素。本文的研究对优化聚芳醚质子交换膜材料提供了有利的借鉴。对磺化聚芳醚质子交换膜材料的广泛应用提供了研究基础。更多还原

【Abstract】 Title: Design and structure - property relationship studies of novel poly(arylene ether) as proton exchange membranesMajor: Polymer Chemistry and PhysicsAdviser: Pro. Jiang ZhenhuaHydrocarbon sulfonated aromatic membranes, particularly sulfonated poly(aryl ether)s, have attracted attention as potential candidates as membrane applied to the production of energy and of clean water. They represent an attractive alternative to perfluorinated sulfonic acid membranes for high temperature proton-exchange membrane fuel cells because of their excellent stability and high glass transition. An increase of the operating temperature to above 100oC promises crucial benefits conceming the complexity, cost and performance of automotive PEMFC systems. Water managenment would be reduced. The properties and durability of fuel cell core components must be further improved to meet market expectations.Early examples of sulfonated poly(aryl ether)s, sulfonic acid were obtained by post-polymerization sulfonation. For high acid content the excessive water swelling and even water solubility of these ionomers limit their applicability. Partial sulfonation results in acid groups that are distributed statistically along the polymer backbone. Unlike perfluorosulfonic acid these hydrocarbon membranes do not usually exhibit the formation of connected water-filled channels that promotes efficient transport of proton across the membrane. A similar issue arose in the case of sulfonated poly(aryl ether)s prepared by polymerization of pre-sulfonated monomers. In this case, high water swelling is avoided by the use of non-sulfonated co-monomers. Therefore, the resulting polymers also had an irregular distribution of sulfonic acid along the polymer backbone. It has been demonstrated that controlling the distribution and location of sulfonic acid can result in well-defined hydrocarbon membrane morphology. As a result of the formation of connected water-filled channels, such membranes have superior proton-conducting properties than statistically sulfonated membranes, particularly at low relative humidity.There are three parts of our research work. First one , Brominated poly(ether sulfones) were prepared and investigated for use as proton-conducting fuel-cell membranes. In the first step, 4-bromophenylquin -one (Br-PQ) and 4-bromophenylhydroquinone(Br-PH) were synthesized according to a previously reported synthetic procedure. Next, poly (ether sulfones) with a 4-bromophenyl pendant group was synthesized based on a bromo-bisphenol. Finally, Brominated poly(ether sulfones) was coupled by dehalogenation with potassium 1,1,2,2-tetrafluoro-2- (1,1,2,2-tetrafluoro-2- iodoethoxy)ethanesulfonate (PSA-K) using copper metal, followed by treatment with aqueous HCl.Second, A series of six sulfonated poly(aryl ether sulfone)s with a strictly alternating repeat unit have been prepared and evaluated as proton conducting membranes. Two efficient and simple synthetic strategies are described to obtain bisphenol monomers composed of four or six phenylene units linked by ether bridges that cannot be subjected to transetherification. Polycondensation of these bisphenol monomers with sulfonated dihalide monomers gave high molecular weight homopolymers. The sulfonated moieties of these homopolymers are separated by monodisperse non-sulfonated spacers corresponding to the bisphenol oligo(ether) monomers. Membranes was obtained by solvent casting method and were characterized by titration, impedance spectroscopy, DSC and TGA. The properties of the membranes were closely related to the connectivity of the non-sulfonated spacers. At identical acid content, the membranes containing meta ether linkages had a lower glass transition than all-para materials. Greater chain mobility resulted in superior proton conductivity. Under 100% relative humidity at 80°C, these materials had proton conductivity up to 216 mS/cm-1. The membrane with an acid content of 2.05 meq g-1 containing exclusively Para linkages had a proton conductivity similar to Nafion together with an excellent stability in boiling water.Finally, cyanide and sulfone groups were introduced in the polymer main chain, and obtained micro block copolymers with the two functional groups were investigated in detailly. The Excellent thermal stability was observed by DSC and TGA. Swelling test results showed that the copolymers have good dimensional stability in specific humidity, specific temperature. The obtained bifunction polymer film exhibited high proton conductivity means our new materials have wide range of applications.更多还原