【作者】 毕慧平；

【导师】 王连军； 陈守文；

【作者基本信息】 南京理工大学 ， 环境工程， 2010， 博士

【摘要】 质子交换膜燃料电池（PEMFC）由于高效、环境友好等优点,在移动设备、汽车及固定装置的能源供应方面显示了很大的潜力。质子交换膜（PEM）是PEMFC的核心部件之在燃料电池中既作为电解质起到从阳极向阴极传输质子的作用,同时也充当燃料与氧化剂的隔膜。目前实际应用的是诸如DuPont公司生产的全氟磺酸型质子交换膜该类膜具有优良的化学稳定性及较高的电导率,但其昂贵的价格、较低的使用温度以及较高的甲醇透过性等缺点限制了其进一步推广。近年来,低成本高性能的PEM替代材料的开发成为研究者关注的焦点。其中,磺化聚芳醚砜（SPAES）类质子交换膜具有质子导电率高、热稳定性、化学稳定性好等优点；SPI类质子交换膜具有优异的成膜性,高的耐热性、机械性能及尺寸稳定性。这些优良的性能使得SPAES和SPI膜作为PEM替代材料,具有很高的应用潜力。但是当离子交换容量（IEC）较高时,SPAES在水中尤其是高温水中的尺寸稳定性较差,需要对其进行进一步改进才能满足PEMFC的需要。本论文将致力于高性能的基于SPAES类质子交换膜的开发及研究,通过交联,引入IPN结构,与SPI复合等方法,制备新型SPAES,质子交换膜,考察它们的尺寸稳定性、导电性及耐久性。在上述研究的基础上,合成了基于聚酰亚胺和磺化聚苯的多嵌段共聚物,并对其电导性、微观形态及耐久性等性能进行了研究。采用发烟硫酸直接磺化法,成功制备了3,3’-二磺化-4,4’-二氟二苯砜（SDFDPS）。考察了发烟硫酸用量、磺化时间、磺化温度等对磺化结果的影响,结果显示,最佳反应条件为SO₃/DFDPS摩尔比为3∶1,反应温度为110℃,反应时间为20 h。通过芳香族亲核取代反应,与4,4’-二氟二苯砜（DFDPS）及4,4’-联苯二酚（BP）经过高温缩聚,得到了高分子量的直链型SPAES聚合物。制备并表征了两种交联型SPAES膜—直接交联型及后交联型SPAES膜：一种是以DFDPS, SDFDPS, BP和1,3,5-三羟基苯（THB）为原料,而合成的一系列不同磺化度、不同交联度的新型直接交联型磺化聚芳醚砜（cSPAES）。采用¹HNMR和FTIR对聚合物结构进行了表征确认。与直链型SPAES相比,cSPAES膜在水中尤其是高温水中的尺寸稳定性得到了较大提高,并得到很高的质子导电率（IEC=2.43 meq/g时,60℃水中的沿膜面方向的质子电导率（σ//）达到261ms/cm,是相同条件下Nafion112σ//（139 ms/cm）的1.9倍）。另一类交联膜是通过向直链型SPAES聚合物中加入脱水剂,通过磺酸基团与高分子主链结构中的活性氢发生脱水交联而形成的通过交联前后聚合物在诸如DMSO、DMAc及NMP等溶剂中溶解性能的改变,证明交联结构被成功引入SPAES内。pSPAES膜在尺寸稳定性方面得到了非常大的提升：pSPAES60-9在130℃水中熟化24h后的径向和膜厚方向的尺寸变化仅有0.41和0.65,远小于cSPAES膜在相同条件下的尺寸变化值。以不同磺化度的直链型SPAES为基础,以P₂O₅为脱水剂,制备了两个系列具有IPN结构的磺化聚芳醚砜（SPAES-IPN）质子交换膜。扫描电子显微镜（SEM）结果表明,两种高分子具有良好的互溶性,复合膜中没有明显的相分离区域。对SPAES-IPN膜进行了系列性能测试,结果显示,SPAES-IPN膜Ⅰ₁₁70保持了较高的质子导电率（IEC=1.95meq/g,在60℃水中σ//=173 mS/cm）,尺寸稳定性和水解稳定性得到了大幅度提高.Ⅰ₁₁70膜在130℃水中浸泡24 h后径向和膜厚方向的尺寸变化仅有0.45和0.51,在130℃浸泡200h后仍然保持了高强度等级。以SPAES（.或cSPAES）和SPI为原料,采用不同配比,合成了两种新型复合质子交换膜（SPAES/SPI和cSPAES/SPI）。SEM的观察没有发现明显相分离区域。复合处理后膜仍然保持了较高的热稳定性,两种复合膜的磺酸基团分解温度均在300℃左右,可以满足高温燃料电池使用的要求。复合膜在水中（尤其是热水中）和甲醇溶液中的稳定性比相应的纯SPAES（或cSPAES）得到了较大提高。与纯SPI相比,复合膜在整个相对湿度范围内均显示了较高的质子导电率以2.5-二氯-3’-磺化苯甲酮（DCSBP）和聚酰亚胺多聚体(PIO_-n)为链段,通过耦合反应,设计合成了一系列新型的聚（2-（3-磺化）苯甲酰基-1,4-亚苯基）-嵌段-聚萘酰胺（PSP-b-PI）嵌段型共聚物膜。TEM结果表明,PSP-b-PI膜存在疏水区域与亲水区域形成的微相分离结构。PSP-b-PI共聚物膜在130℃下具有很好的水稳定性。尽管PSP-b-PI共聚物膜在尺寸变化方面呈现了很强的各向异性特点,而在电导率方面基本上为各向同性。这类膜在水中,甚至在较低的相对湿度下都具有非常高的垂直膜面方向的质子导电率。IEC为1.5 meq/g的PSP-b-PI膜在PEMFC中显示出很高的性能。更多还原

【Abstract】 Proton exchange membrane fuel cells （PEMFC）, due to their high efficiency and environmental friendship, have shown promise as alternative portable, automotive, and stationary power sources. One of the important components in a PEMFC is the proton exchange membrane （PEM）, which serves as the electrolyte that transfers protons from the anode to the cathode and separates the fuel and oxidizer. The state-of-the art PEMs are perfluorosulfonic acid membranes such as Nafion manufactured by DuPont. These membranes showed excellent chemical stability as well as high proton conductivity. However, Nafion suffers from disadvantages, including high cost, high methanol permeability, and limited operating temperature （80℃）, due to its depressed hydrated a relaxation temperature. In recent years, the increasing demands of PEMs with high performance and low cost have stimulated the intensive researches on the development of alternatives. Among them, sulfonated poly（arylene ether sulfon）s （SPAESs）were drawn the attraction because of their high proton conductivity, high chemical and thermal stabilities. While sulfonated polyimides （SPIs）were widely studied due to their good film-forming ability, excellent thermal and mechanical stability, and excellent dimensional stability in hydrated state. So. SPAES and SPI were considered as the promising alternatives for PEMFC applications. However, the SPAES with ion exchange capacity （IEC） excesses 1.80 meq/g tend to extremely swellingand lost its mechanical stability. Only the further improvement in PEMFC performance, SPAES-based membranes should be met the need for PEMFC.This dissertation focuses on the development of SPAES-based membranes by the methods including cross-linking, interpenetrating and blending.Their performances such as dimensional stability, proton conductivity and durability investigated. Based on the former study, novel sulfonated polyphenylene-b-polyimide （PSP-b-PI） block copolymers were developed and their proton conductivity, microphase and durability were also investigated.A well optimized synthetic method was developed for 3,3’-disulfonate-4,4’-difluorodiphenyl sulfone （SDFDPS） by direct sulfonated from industrial grade 4,4’-difluorodiphenyl sulfone （DFDPS） with fumic sulfuric acid. The optimized reaction condition was found as that the molar ratio of SO₃ to DFDPS is 3:1 with a reaction temperature of 110℃for 20 h. Poly （arylene ether sulfone） copolymer prepared from the synthesized SDFDPS showed a high relative viscosity.Two types of cross-linked SPAES-based membranes were successfully developed. One is named cSPAES, which were obtained from the directly compolymerization of DFDPS, 4,4-biphenol （BP）, SDFDPS.and 1.3,5-trihydroxy benzene （THB）, and the structure was confirmed by ¹HNMR and FTIR. Tough and flexible cSPAES membranes were obtained through solution casting method. Compare to line structure type of SPAES. cSPAES membranes showed higher dimensional stability in water especially in hot water. These membrane showed much high proton conductivity at some high IEC level（IEC=2.43 meq/g.σ//=261 mS/cm, which was 1.9 times to that of Nafion）.. The other one is named pSPAESs, which were obtained via the dehydration reaction between the sulfonic acid groups and the activated hydrogen atoms of SPAES in the presence of phosphorus pentoxide. The crosslinked structure was confirmed by the insolubility in organic solvents such as DMSO, DMAc and NMP. pSPAES membranes showed greatly improved water stability. Forexample, after aging in water for 24 h at 130℃, the dimensional change in plane and thickness of pSPAES60-9 were just 0.41 and 0.65, respectively, which were much lower than those of cSPAES.A series of SPAES-based blend membranes （SPAES-IPN） with interpenetrating polymer network （IPN） structure were prepared successfully from SPAESs with various IEC level. The scanning electron microscopy （SEM） proved the miscibility of the system and membrane uniformity. The SPAES-IPN membranes exhibited significantly improvement in dimensional and hydrolytic stability, and reasonably high proton conductivity was maintained. （）. For example, for In70（IEC=1.95 meq/g）, which showed 173mS/cm in water at 60℃, after aging in water for 24 h at 130℃, the dimensional changes in plane and thickness direction were 0.45, and 0.51, respectively.And this membrane also displayed much high toughness after aging in 130℃water for 200 h.Two series of SPAES/SPI and cSPAES/SPI blend membranes were prepared from SPAES （or cSPAES） and SPI. The miscible structure of the blend membranes was confirmed by SEM. Thermogravimetry analysis demonstrated that the blend membranes were stable up to 300℃. By the introduction of SPI, the blend membranes showed much higher hydrolytic stability and methanol tolerance than the corresponding SPAES （or cSPAES） membranes. The blend membranes showed higher proton conductivity than the corresponding SPI membranes in the whole range of relative humidity.Novel poly （2-（3-sulfo） benzoyl-1,4-phenylene）-block-polynaphthalimide （PSP-b-PI） copolymers were successfully synthesized by Ni（0） catalytic copolymerization of 2,5-dichloro-3’-sulfo-benzophenone and dichloro-terminated naphthalimide oligomer. TEM results suggested that microphase-separated structure for the hydrophilic domain and hydrophobic domain were presented in these membranes. PSP-b-PI membranes showed good hydrolytic stability at 130℃Although with high isotropic performance for the dimensional change, PSP-b-PI membranes showed anisotropic performance for proton conductivity. These membranes showed high through-plane conductivity in water as well as under low relative humidity. The PSP-b-PI membrane with IEC of 1.5 meq/g showed high PEFC performance.更多还原