基于多季铵化咔唑衍生物侧链聚芳醚酮的制备及性能研究

发布时间：2018-03-26 19:09

本文选题：侧链　切入点：季铵化　出处：《吉林大学》2017年硕士论文

【摘要】：随着目前全球环境和能源问题越来越严重,人们在寻求新的能源选择上已经做出巨大努力。燃料电池作为一种新能源技术,由于其高效、稳定、较低甚至零排放的优势,已经显示出巨大的应用潜力。其中,质子交换膜燃料电池(PEMFC)拥有能量转化效率高、隔绝燃料能力强、可低温启动等优点,这些优点使其得到了长足的研究和发展。但同时PEMFC必须使用昂贵的铂电极催化剂,这极大地影响了其商品化。而阴离子交换膜燃料电池(AEMFC),使用和质子交换膜燃料电池类似的导电聚合物膜作为电解质,不仅兼具了PEMFC的部分优点,而且可以使用钴、镍等非贵金属催化剂作为电极材料,比起PEMFC更加经济实惠。这些都引起了科研工作者的广泛关注。阴离子交换膜(AEM)作为AEMFC的核心部件,目前为止并没有符合要求的商品化膜被开发出来,这主要是因为当前大部分的AEM普遍存在电导率不高、尺寸稳定性和化学稳定性差等原因。为了解决这些问题,科研工作者们一般通过合成新的阴离子导电基团或是特定聚合物结构的设计来改进AEM的性能。前者大多集中于对多种不同的阴离子导电基团的阴离子传导性和化学稳定性的研究;后者则更多关注于通过聚合物分子结构设计,得到性能优异的AEM。起初很多研究者尝试在PPO或聚芳醚的主链直接季铵化得到相应的AEM,但是当季铵化程度过高时,AEM在水中表现出不可控制的溶胀,过多的吸水又增加了氢氧根亲核进攻的风险。因此更多的研究者尝试在聚合物侧链引入季铵基团使亲疏水相分离;同时将季铵基团密集化,形成更加聚集的亲水相。这样便可以达到在保证离子传导率的同时降低膜的尺寸变化的目的。因此,我们在本论文中引入这样的思想,设计合成侧链密集季铵型的聚合物结构,以希望得到离子传导率、尺寸稳定性和化学稳定性等性能相对优异的AEM材料。在第一部分实验中,我们选取聚芳醚酮作为疏水链骨架,将制备得到的含碘的对苯二酚与4,4'-二氟二苯甲酮和双酚AF三元共聚制备一系列侧链含碘的聚芳醚酮I-PAEK-x;随后通过Suzuki偶联反应制得含四苄基咔唑接枝单体,并通过乌尔曼偶联反应接枝得到侧链含四苄基咔唑的聚芳醚酮MeCz-PAEK-x;对MeCz-PAEK-x用NBS和BPO进行自由基溴化得到BrCz-PAEK-x。由于咔唑上的苯环发生溴化消耗部分NBS,因此通过多次试验摸索满足要求的溴化条件。随后进行铺膜、胺化得到QACz-PAEK-x阴离子交换膜。对得到的一系列聚合物进行表征,发现I-PAEK-x的接枝率和MeCz-PAEK-x的溴化率均在80%以上,基本满足我们的需求。另测得QACz-PAEK-x兼具较为良好的尺寸稳定性、离子传导性能和化学稳定性。特别是与其他主链型季铵化阴离子交换膜相比,QACz-PAEK-x在相同IEC的条件下有更高的传导率和更低的溶胀。这些优异的性能归因于其侧链密集季铵化的结构导致的明显的亲疏水微相分离,从而更有利于形成离子传输通道。同时,QACz-PAEK-x在4 mol/L Na OH溶液中表现出较好的碱稳定性,这主要是由于连续共轭的咔唑基团对氢氧根的进攻有一定抑制作用。当然,由于连续的刚性侧链结构的引入使得聚合物在IEC升高时力学性能下降。在随后的第二部分实验中,为了保持侧链密集季铵化结构的优势,同时规避QACz-PAEK-x中过于刚性的分子结构、亲疏水链段间距不足等劣势,我们在疏水主链和亲水侧链之间构建长的烷基间隔。在具体的实验操作上,我们通过将1,6-二溴己烷和第一部分实验合成的含四苄基咔唑反应得到接枝单体,并接枝到含有酚羟基的聚芳醚酮PAEK-OH-x上得到侧链含长烷基四季铵化咔唑的聚芳醚酮PAEK-HMeCz-x。对其进行自由基溴化、铺膜和季铵化便得到含长烷基四季铵化咔唑侧链的聚芳醚酮阴离子交换膜PAEK-HQACz-x。对PAEK-HQACz-x膜进行性能测试,发现IEC最高的PAEK-HQACz-0.7在80 oC的条件下氢氧根传导率可以达到98.1 mS/cm。而PAEK-HQACz-x在保证一定拉伸强度的同时,断裂伸长率比起QACz-PAEK-x有了明显的提高。相应地,PAEK-HQACz-x的碱稳定性有了一定的改善。这些主要是由于烷基链的给电子作用在一定程度上抑制氢氧根离子对苄基季铵盐的亲核进攻。综上所述,本论文以聚芳醚酮作为疏水主链,在侧链分别引入了自由体积大的刚性四苄基季铵化咔唑和有长烷基链间隔的四苄基季铵化咔唑,并对二者进行结构表征和性能测试,同时对得到的结果进行讨论与分析,证实了侧链密集季铵化阴离子交换膜优良的性能和潜在的应用前景。
[Abstract]:With the current global environmental and energy issues are becoming more and more serious, people are looking for new alternative energy has made a great effort. The fuel cell as a new energy technology, because of its high efficiency, stable, low or zero emissions, has shown great potential. Among them, the proton exchange membrane fuel cell (PEMFC) has high energy conversion efficiency, fuel isolation capability, low temperature starting advantages, these advantages make its research and development greatly. But at the same time PEMFC must use platinum electrode catalyst is expensive, which greatly affect the commercialization. The anion exchange membrane fuel cell (AEMFC), and the use of proton exchange membrane fuel cell conductive polymer such as electrolyte, not only has some advantages of PEMFC, but also can use Cobalt, nickel and other non noble metal catalysts used as electrode material, by more than PEMFC Economic benefits. These have attracted much attention of research workers. The anion exchange membrane (AEM) as the core component of AEMFC, so far did not meet commercial requirements of the film to be developed, this is mainly because the most prevalent AEM conductivity is not high, size stability and low chemical stability to reason. To solve these problems, researchers generally through the synthesis of new anionic groups or specific properties of conductive polymer structure to improve the design of AEM. The former research mostly focused on anion conductive groups of different anion conductivity and chemical stability; the latter is more focused on the design of the polymer structure, get the backbone direct quaternary ammonium the excellent performance of AEM. at first, many researchers try to PPO or poly aryl ether of corresponding AEM, but when the degree of quaternization is high, AEM Exhibit swelling can not control too much water in the water, but also increases the risk of hydroxyl nucleophilic attack. Therefore, more and more researchers try to introduce polymer side chain quaternary ammonium groups to hydrophobic phase separation; and quaternary ammonium groups denser, more hydrophilic aggregation phase formation. This can be achieved in the at the same time to ensure the ionic conductivity decreases the size change of the film. Therefore, we introduce the idea in this paper, the polymer structure design and synthesis of side chain density of quaternary ammonium type, hope to get ionic conductivity, AEM material is relatively excellent performance of dimensional stability and chemical stability. In the first part of the experiment. We selected poly aryl ether ketone as the hydrophobic skeleton, the prepared iodine containing hydroquinone and two 4,4'- fluoride two benzophenone and bisphenol AF three were prepared by the copolymerization of a series of side chain containing poly aryl ether ketone with I-PAEK-x; Through the Suzuki coupling reaction system containing four benzyl carbazole monomer, and containing four benzyl carbazole side chain poly aryl ether ketone MeCz-PAEK-x by grafting Ullman coupling reaction; MeCz-PAEK-x NBS and BPO free radical bromination of benzene BrCz-PAEK-x. carbazole as raw bromide NBS consumption environment, so by repeatedly meet the test requirements of bromide. Then filming, imidization of QACz-PAEK-x anion exchange membrane. Characterization of a series of polymers are found, bromination rate of I-PAEK-x grafting rate and MeCz-PAEK-x were more than 80%, basically meet our needs. The other measured QACz-PAEK-x has good dimensional stability, ion conductivity and chemical stability. Especially with the other main chain type quaternary ammonium anion exchange membrane, QACz-PAEK-x has a higher transmission rate and more under the same conditions IEC Low swelling. These excellent properties are attributed to the structure of the side chain of dense quaternized leads to obvious hydrophobic microphase separation, which is more conducive to the formation of ion transfer channels. At the same time, QACz-PAEK-x showed better stability of alkali in the 4 mol/L Na OH solution, which is mainly composed of Carbazole in continuous conjugate the hydroxyl attack has certain inhibitory effect. Of course, the introduction of rigid side chain structure makes the continuous decline in mechanical properties of polymer in IEC increased. In the second part of subsequent experiments, in order to maintain the advantages of side chain intensive quaternary structure, while avoiding the molecular structure of QACz-PAEK-x is too rigid and hydrophobic chain some distance disadvantage, we construct the interval between hydrophobic long alkyl chains and hydrophilic side chains. In the specific experimental operation, we will 1,6- dibromo hexane and into the first part of the experiment Containing four benzyl carbazole reaction of grafting monomer, and grafting to containing phenolic hydroxyl poly aryl ether ketone PAEK-OH-x obtained by free radical bromination of four with long alkyl ammonium carbazole side chain poly aryl ether ketone PAEK-HMeCz-x. film and quaternized by poly aryl ether ketone anion exchange membrane containing PAEK-HQACz-x. long alkyl ammonium four carbazole side chain to test the performance of the PAEK-HQACz-x film, found that the highest IEC PAEK-HQACz-0.7 at 80 oC under the condition of hydroxide conductivity can reach 98.1 mS/cm. and PAEK-HQACz-x in a certain tensile strength and elongation rate compared to QACz-PAEK-x has been significantly improved. Accordingly, the stability of PAEK-HQACz-x with alkali a certain improvement. These are mainly due to the electronic effect of alkyl chain in a certain extent inhibit hydroxyl ion nucleophilic attack of benzyl quaternary ammonium salt. In summary, this thesis based on poly Aryl ether ketone as a hydrophobic backbone, a rigid four benzyl quaternary ammonium carbazole large free volume and four benzyl with long alkyl chains between quaternized carbazole were introduced in the side chain, and the structure characterization and performance test of the two at the same time, the results of discussion and analysis, confirmed the side chain intensive quaternary ammonium anion exchange membrane with excellent properties and potential applications.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.48;TQ317

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