【作者】 姚丙建；

【导师】 鲁在君；

【作者基本信息】 山东大学 ， 高分子化学与物理， 2014， 博士

【摘要】 燃料电池是一种清洁、高效的绿色环保能源,质子交换膜则是其核心部件,它为质子的迁移和输送提供通道,使得质子能够透过膜而从阳极到达阴极,与外电路的电子转移构成回路,向外界提供电流。因此质子交换膜的性能对燃料电池的性能起着非常重要的作用,它的好坏直接影响燃料电池的使用寿命。目前商业采用的是以Nafion为代表的全氟磺酸型质子交换膜,全氟磺酸膜具有高的质子电导率、化学稳定性和热稳定性,但高甲醇渗透性、高成本及温度依赖性的缺点阻碍了其在直接甲醇燃料电池中的发展和应用。含磺酸基的聚酰亚胺、聚苯并咪唑、聚芳醚砜等材料具有较好的耐热性能,但在磺化度较低时,质子电导率偏低,当磺化度达到一定值时,其尺寸稳定性、机械强度和阻醇性能又出现严重下降,同样降低了磺化芳香族聚合物的应用潜力。交联磺化芳香族聚合物可以有效提高了质子交换膜的综合性能,特别在抑制质子交换膜的过度溶胀和减少甲醇渗透方面效果显著。因此,本文首次以耐热性高、耐酸性强、化学稳定性好、成本低廉的聚苯并噁嗪作为骨架网络结构,通过分子设计将磺酸基团引入到聚苯并嗯嗪交联骨架上,来制备磺化聚苯并噁嗪质子交换膜,并对其合成、性能开展了系统研究,主要研究内容和结果如下：第一部分基于4-羟基苯磺酸钠的主链磺化型聚苯并噁嗪质子交换膜以二苯甲烷二胺、4-羟基苯磺酸钠、多聚甲醛为原料,合成了磺化苯并噁嗪单体,通过单体溶液的热浇注、固化成膜制备了磺化聚苯并噁嗪膜材料,该膜具有高的电导率和突出的阻醇性能。结果显示,甲醇渗透系数为5.8×10-8cm2s-,尤其适用于直接甲醇燃料电池,以其为组件的直接甲醇燃料电池测试结果表明,电池可以使用高达7M的甲醇浓度,目前在纯膜中报道最高。第二部分基于腰果酚的主链磺化型聚苯并噁嗪质子交换膜在第一部分的研究基础上,针对干膜韧性较差的缺点,我们选用含脂肪族柔性链的腰果酚为酚源,以双磺酸基联苯胺为胺源,合成了磺化聚苯并噁嗪质子交换膜。侧链分子长链为聚苯并噁嗪交联体系提供内增塑作用,在增加磺化聚苯并噁嗪薄膜的成膜性和柔韧性的同时,保证了高的质子传导率和较低的甲醇渗透系数。第三部分基于大麦芽碱的侧链磺化型聚苯并噁嗪质子交换膜我们又通过分子设计,选用含叔胺基团的大麦芽碱为酚源,与二苯甲烷二胺、多聚甲醛反应,得到含叔胺基团的苯并噁嗪单体,进而利用单体中叔胺基团的反应活性,与丙基磺酸内酯反应,得到侧链磺化的磺化聚苯并噁嗪薄膜,该结构通过在均聚合物内构建新的具有选择性的离子通道,并在聚苯并噁嗪共价交联的基础上,通过铵盐和磺酸之间的相互作用形成物理交联结构,进一步增加了聚合物分子的相互作用,从而更好地调节质子交换膜的参数平衡,在提高低湿度下质子导电率的同时,也进一步提高膜的尺寸稳定性和阻醇性能。综上所述,作为新型的非氟磺化聚电解质,磺化聚苯并噁嗪在质子交换膜燃料电池中具有一定的应用前景。更多还原

【Abstract】 Fuel cell is a clean and efficient energy source for an environmentally responsible planet. Proton exchange membranes (PEMs) are key components of polymer fuel cells because they can provide an ionic pathway for proton transfer while prevent the mixing of reactant gases. Therefore, the property of a proton exchange membrane plays a very important role in the fuel cell performance. The most widely used PEM is Nafion membrane commercially available from DuPont. Nafion is the state-of-the-art material due to its high proton conductivity, good chemical and thermal stability. However, further application of Nafion is hinderedby high methanol crossover rate for direct methanol fuel cells (DMFCs), the strong temperature dependence of its proton conductivity, and the high cost. Alternative proton conducting materials, such as sufonic acid containning polyimides, polybenzimidazoles, and poly (arylene ether sulfone), exhibit excellent thermal stability, but the dimensional stability, mechanical strength, and methanol selectivity was poor with high degree of sulfonation, which also reduces the potential application of these sulfonated aromatic polymers. Crosslinked sulfonated aromatic polymers can effectively improve the overall performance of proton exchange membrane, particularly for the inhibition the excessive welling and reducing the methanol crossover behavior of PEMs. Thus, this paper firstly uses polybenzoxazine with high heat and acid resistance, and low cost propertis as the host network of the PEM. The sulfonic acid groups were intruduced to the benzine ring of polybenzoxazine by simple molecular design. The synthesis and property of sulfonatedPart one:Main chain-type sulfonic acid-containing polybenzoxazine based on sodium4-hydroxybenzenesulfonateThe sulfonic acid-containing benzoxazine monomer, abbreviated as SHS-ddm, was synthesized via Mannich reaction and acidizing reaction using sodium4-hydroxybenzenesulfonate,4,4’-diaminodiphenylmethane, and paraformaldehyde as raw materials. The crosslinked sulfonic acid-containing polybenzoxazine [poly (SHS-ddm)] membrane was prepared through high temperature solution casting of the monomer. Our results showed that poly(SHS-ddm) membrane exhibited a high proton conductivity and a very low methanol permeability of5.8×10-2cm2s-1, which is especially suited for direct methanol fuel cells. Employing this membrane in the membrane-electrode assembly (MEA), high methanol concentration up to7M was used, which is the highest one as reported for the pure PEM.Part two:Main chain-type sulfonic acid-containing polybenzoxazine based on cardanol.Based on the study of part one, we aim to improve the toughness of sulfonic acid-containing polybenzoxazine membrane by using a flexible aliphatic chain cardanol as the phenol source. The long aliphatic chain in each repeat unit of polybenzoxazine structure provide the plasticizing effect on the crosslinked macromolecules, which increased the flexibility of solfonic acid-containning polybenzoxazine membrane while ensuring its proton conductivity and low methanol permeability.Part three:Side chain-type sulfonic acid-containing polybenzoxazine based on hordenine.The hordenine-based benzoxazine monomer was synthesized via Mannich reaction and acidizing reaction using hordenine,4,4’-diaminodiphenylmethane, and paraformaldehyde as raw materials. Then, the sulfonic acid group was introduced via the reaction of1,3-propane sultone and hordenine-based benzoxazine monomer. A new selective ion channels was constructed in the homopolymer by the existence of zwitterionic groups. The physical interaction between the sulfonic acid and quaternary ammonium group can increase the macromolecule interaction so as to better adjust the balance of the membrane parameters. Properties of conductivity under low humidity, the dimensional stability and the methanol permeability will be improved simultaneously.In summary, as a novel non-fluorinated sulfonated polyelectrolyte, sulfonic acid-containning polybenzoxazine has the potential in the proton exchange membrane fuel cells.更多还原