【作者】 肖继春；

【导师】 陈义旺； 周魏华；

【作者基本信息】 南昌大学 ， 材料物理与化学， 2010， 硕士

【摘要】 质子交换膜燃料电池(PEMFC)和直接甲醇燃料电池(DMFC),因其具有安全、高效、无污染等特点,已成为当今能源领域的研究热点。质子交换膜(PEM)是燃料电池的核心组件之一。当前广泛使用的Nafion膜,由于高的甲醇渗透率、在高温及低湿条件下质子传导率大幅降低及高昂的成本等制约了其大规模应用。开发质优价廉的新型质子交换膜已成为燃料电池研究中的一个新热点。磺化聚芳醚酮具有优异的机械性能、热氧化稳定性以及较高的质子传导率,被认为是制备质子交换膜的优良材料。碳纳米管具有独特的电学性能,优良的力学性能及良好的化学稳定性,是聚合物基体的良好增强材料。磺酸基功能化修饰的碳纳米管与聚合物有良好的相容性,将其分散于磺化聚芳醚酮制备复合质子膜,有望结合两者的优势,实现质子传导率和力学性能提高同时甲醇透过率降低。本文以4,4’-二苯氧基二苯砜(DPODPS)与间苯二甲酰氯(IPC),在1,2-二氯乙烷(DCE)/N-甲基吡咯烷酮(NMP)/无水三氯化铝(AICl3)复合催化剂溶剂体系中,通过低温溶液亲电缩聚法合成了聚醚砜醚酮酮(PESEKK)。以浓硫酸为溶剂、氯磺酸为磺化剂对PESEKK进行磺化改性,通过改变磺化反应时间,制备了一系列不同磺化度(DS)的磺化聚醚砜醚酮酮(SPESEKK)。采用核磁共振氢谱(1H NMR)对PESEKK、SPESEKK进行表征,结果表明产物具有预期的化学结构。通过热重分析仪(TGA)和差示扫描量热仪(DSC)对聚合物进行了热稳定性表征。以N,N-二甲基甲酰胺(DMF)为溶剂制备了一系列不同磺化度的SPESEKK膜,并对膜的吸水率、离子交换容量(IEC)、质子传导率及甲醇透过率进行了测试。结果表明,SPESEKK具有良好的热稳定性；随着磺化反应时间和磺化度的增加,所得SPESEKK膜的吸水率、离子交换容量及质子传导率均提高；SPESEKK膜具有优异的阻醇性能,其甲醇透过率为7.02×10-8至4.48×10-7cm2·s-1,比商业化的Nafion115低一至两个数量级。通过扫描电镜(SEM)对SPESEKK膜的断面形貌进行了表征。将多壁碳纳米管(MWCNTs)用浓硝酸和浓盐酸组成的混酸刻蚀后,在较高温度下用浓硫酸进行磺化处理,得到磺酸基功能化的碳纳米管(sCNTs)。超声作用下将sCNTs分散于SPESEKK (DS= 0.58)的N,N-二甲基乙酰胺(DMAc)溶液中,采用流延成膜法制备了一系列不同掺杂量的sCNTs-SPESEKK复合质子膜。采用傅里叶变换红外光谱仪(FT-IR)对sCNTs的结构进行了表征,并考察了其在几种常用溶剂中的分散稳定性。对复合膜的断面形貌、力学性能、质子传导率及甲醇透过率进行了表征和测试。结果表明,经浓硫酸处理后,磺酸基团被成功地引入到碳纳米管表面；sCNTs在水和DMAc中均匀分散,并能在DMAc中长期稳定分散；SEM结果表明,sCNTs在SPESEKK基体中均匀分散；sCNTs的掺入,提高了SPESEKK膜的拉伸强度和质子传导率的同时降低了其甲醇透过率,且随着掺入量的增大,其复合膜的拉伸强度和质子传导率随之提高,甲醇透过率随之降低。更多还原

【Abstract】 Proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), are receiving considerable attention as transport, stationary, and portable future power sources because of their low emissions and high energy conversion efficiency. The proton exchange membrane (PEM), is the key component of the PEMFCs. Nafion, one of the perfluorosulfonic acid membranes, is the current state-of-the-art PEM material. However, several drawbacks of Nafion, such as high cost, high methanol permeability, low humidity and a major reduction in conductivity at high temperatures, have led researchers to investigate promising alternatives.Sulfonated poly(aryl ether ketone)s (SPAEKs), are receiving considerable attention as a kind of promising PEM for their excellent high thermal stability, mechanical properties, oxidation resistance and high proton conductivity. Owing to their unique mechanical properties and excellent high chemical stability, carbon nanotubes (CNTs) are considered to be ideal candidates for polymer reinforcement. Sulfonic acid group functionalized CNTs (sCNTs) are believed to be homogeneously dispersed within the SPAEKs matrix. It is easy to afford sCNTs/SPAEKs composite membranes.by a solution casting method. The composite membranes are expected to exhibit enhanced mechanical properties, improvements in proton conductivity and reduced methanol permeability compared with the neat SPAEKs membrane.The poly(ether sulfone ether ketone ketone) (PESEKK) was synthesized by the low temperature solution polycondensation of 4,4-bis(Phenoxy)diphenyl sulfone (DPODPS) and isophthaloyl chloride (IPC) in 1,2-dichloroethane and in the presence of aluminum chloride (AICl3) and N-methylpyrrolidone (NMP). A series of sulfonated poly(ether sulfone ether ketone ketone) (SPESEKK) with different degree of sulfonation (DS) are prepared by the postsulfonation of PESEKK using chlorosulfonic acid as sulfonating agent and concentrated sulfuric acid as solvent. The chemical structures of the polymers are analyzed by the 1H NMR. The thermal properties of the SPESEKK are studied, showing that they are greatly influenced by the DS value and sulfonation time. The water uptake, proton conductivity and IEC values increase as the sulfonation time increasing. The methanol permeability of the SPESEKK in the range of 7.02×10-8 to 4.48×10-7 cm2·s-1, is one or two orders of magnitude lower than that of Nafion 115. The morphology of the SPESEKK membranes is investigated by scanning electron microscope.A series of composite membranes consisting of sulfonated carbon nanotubes (sCNTs) and SPESEKK (DS=0.58) were successfully fabricated via the solution casting method. The chemical structure, as well as the long-term stability of the sCNTs in different solvents was investigated by FTIR analysis and solubility experiment, respectively. The morphology, tensile strength, proton conductivity and methanol permeability of the composite membranes were also investigated. The SEM observation indicated the good dispersion of the carbon nanotubes in polymer matrix, as well as the strong interfacial bonding between the SPESEKK matrix and sCNTs. The addition of either pristine carbon nanotubes or modified carbon nanotubes significantly enhanced the tensile strength of the SPESEKK membrane. The proton conductivity of the SPESEKK membrane increased while the methanol permeability decreased as the sCNTs content increasing, showing a strong interaction between the modified nanotubes and SPESEKK.更多还原