【作者】 薛艳红；

【导师】 徐铜文； Lee JimYang；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2009， 博士

【摘要】 伴随着科技和经济的发展,环境污染、全球变暖、化石燃料日益枯竭等资源与环境问题开始阻碍了人类社会的可持续发展。在这些问题的诸多解决方案中,膜技术由于其简单高效、无污染、节能等优点引起了人们的日益关注。本论文立足于可使用于清洁生产的双极膜电渗析技术和替代化石能源的燃料电池技术,重点研究这两个过程中的的双极膜和质子交换膜的制备。在双极膜制备方面,由于双极膜的中间界面层对双极膜性能至关重要,所以本论文分别选取AgCl-明胶、超支化聚合物等作为催化层,制备新型多层结构双极膜,并对双极膜中间界面层物质对双极膜水解离能力的影响作了深入研究:在质子交换膜制备方面,引入酸碱离子对和有机无机杂化思想,制备出可使用于直接甲醇燃料电池的高性能质子交换膜,并对其燃料电池方面的特性进行了考察。主要研究结果表明:(1)采用氯化银/明胶修饰双极膜中间层可以有效催化水解离,提高双极膜的应用性能。单独的银离子可以通过形成氯化银有效地催化双极膜的水解离,吸附的氯化银的量对所制备的双极膜的水解离性能有较大的影响。采用单独的明胶溶液修饰双极膜中间界面层时,其催化水解离效果取决于其亲水性和空间位阻效应之间的竞争。而硝酸银和明胶的复合溶液修饰双极膜中间界面层时,具有协同催化作用,其催化效果优于同浓度下单纯硝酸银溶液或者明胶溶液处理后的情况,并且该类双极膜在应用过程中由于明胶对银离子的固定作用而表现得更加稳定。(2)具有大量的羟基官能团的Boltorn(?)系列超支化聚酯作为双极膜中间界面层也可以有效催化水解离。超支化聚酯浓度,代数对双极膜性能均具有很大影响,亲水性和空间位阻效应共同决定了水解离催化效果。除此以外,超支化聚合物的端基官能团也是影响双极膜水解离性能的重要因素,端基官能团的亲水性越高,越促进水解离,其中分子间氢键起到关键作用。(3)壳聚糖和磺化聚醚醚酮(SPEEK)之间可以形成酸碱离子对交联,由这两者酸碱共混制备出的复合型质子交换膜的吸水率和溶胀性相对于单纯的磺化聚醚醚酮膜来说得到了很大改善,热稳定性也很好;磺化度为71.4%的SPEEK与壳聚糖以5:1摩尔比共混制备的质子交换膜,其与燃料电池有关的一些性质甚至可以与商品化的Nafion 117相媲美。(4)利用3-氨丙基三乙氧基硅烷和磺化聚醚醚酮可以在质子交换膜制备过程中同时引入酸碱离子对交联以及有机无机杂化,改性后得到的杂化复合膜具有较高的质子传导率,较好的阻醇性,很好的热稳定性、尺寸稳定性以及机械稳定性。随着高效稳定的双极膜和质子交换膜的研制成功,双极膜电渗析和燃料电池技术将获得更大规模的应用,为工业的可持续发展做出更大的贡献。更多还原

【Abstract】 Along with the deveolpmemt in technology and economy,energy and environmental problems,such as environmental pollution,global warming,and depletion of fossil fuels,have been holding back the sustainble development in human society.To cope with this situation,many solutions have been proposed.Membrane technology,due to its simplicity,high efficiency,low energy consumption,and environmental benignity,attracts increasing attention from the academia and industry.For cleaning production and alternative energy supply,bipolar membrane electrodialysis and fuel cells are two promising membrane techniques.Accordingly, the focus of this dissertaion falls on the preparation of multi-layer bipolar membranes and proton exchange membranes for application in the two processes mentioned above.With regard to bipolar membrane fabrication,since the intermediate layer plays a crucial role in bipolar membrane performance,AgCl-glutin,hyperbranched polyester and its derivatives were chosen as catalysts,and their catalytic effect on water splitting was investigated extensively.As for proton exchange membranes,two concepts - acid-base polymer blending and organic-inorganic hybridizaton - were incorporated into membrane preparation,and a series of high-performance proton exchange membranes for direct methanol fuel cells(DMFCs) were obtained.The main experimental results are listed below.(1) The introduction of AgCl/Glutin into bipolar membrane intermediate layer can catalyze water splitting effectively and thus makes the bipolar membrane suitable for industiral applications.When silver ions are introduced alone into the intermediate layer,they exist in the form of AgCl and act as a catalyst for water splitting.The amount of absorbed AgCl affects water splitting significantly.If glutin is introduced alone into the intermediate layer,the catalytic effect on water splitting depends on the competition between hydrophilicity and steric effect.However,when silver ions and glutin are introduced into the intermediate layer together,they can have a synergic effect and catalyze water splitting better than silver ions alone or glutin alone; moreover,the bipolar membrane’s performance is more stable due the immobilizaton of silver ions by glutin.(2) Hyperbranched Boltorn(?) polyesters possess plentiful hydroxyl end groups and also can catalyze water splitting.Both the amount of absorbed hyperbranched polyester and the generation of the polyester play an important role in bipolar memnbrane performance,which is a result of the competition between hydrophilicity and steric effect.Furthermore,the end group of hyperbranched polymer is another important factor affecting water splitting,and the hyperbranched polymer with highlier hydrophilic end groups is the better catalyst,which is due to the formation of hydrogen bonding between hyperbranchend polyester and water moleculars.(3) A series of SPEEK/chitosan composite membrane were prepared by acid-base blending.Compared to pure SPEEK membrane,the composite membrane exhibited reduced water uptake and membrane swelling,and excellent thermal stability.The performance of the composite membrane prepared at the molar ratio of SPEEK(71.4%of sulphonation degree) to chitosan 5:1 is even comparable to commercial Nafion 117.(4) Novel proton-conducting membranes were prepared from sulfonated poly(ether ether ketone)(SPEEK) and 3-aminopropyltriethoxysilane(APTES) by acid-base blending and organic-inorganic hybridization.These acid-base hybrid membranes exhibited high proton condunctivity,low methanol permeability,and excellent thermal,dimensional,and mechanical stabilities.Upon successful preparation of bipolar membranes and proton exchange membranes with good and stable performance,there will be more large-scale applications for bipolar membrane electrodialysis and fuel cells,which will make more contribution to industrial sustainable development.更多还原