化学稳定的磺化聚酰亚胺质子交换膜的合成及其表征

质子交换膜存在的最大问题是膜的水稳定性问题(包括水解稳定性、尺寸稳定性和溶解稳定性),对于磺化聚酰亚胺膜来说,由于存在酰亚胺环,因此他最大的问题是水解稳定性问题.基于这些问题,本文合成了一系列的化学稳定的(水、氧化和热稳定)磺化聚酰亚胺用做质子交换膜材料,所有的聚合物都表现出良好的成膜性、机械性能和热稳定性.首先,联萘二酐(BTDA)的引入,大大的提高膜的水解稳定性,例如Ia-90在90℃的水中1000 h还能保持原有的机械性能,而以NTDA为基础的膜24 h就失去了原有的机械性能.同时,在分子链中引入碱性的二胺基团,例如,苯并咪唑等;碱性的基团和磺酸基团形成聚合物盐,增强了链间的相互作用,降低了膜的吸水率,提高了尺寸稳定性.例如Ia-90和Ic-90具有相近的IEC值,但是由于聚合物中碱性基团和磺酸形成的分子间作用力,Ia-90的吸水率(65%)低于Ic-90(79%);吸水率的降低,同时也降低了膜的甲醇透过率.在保持这些优良性能的同时,为了提高膜的氧化稳定性和质子导电率,以新型的全芳香结构的磺化二胺(2,2'-BSBB)合成了一系列的不同磺化度的磺化聚酰亚胺(Ⅱ),所得聚合物具有良好的成膜性,在保持良好的机械性能、高热稳定性等的前提下,由于全芳香磺化二胺的引入,大大的提高了膜的氧化稳定性;尤其是Ⅱa-6110膜,开始溶解的时间大于40 h,远大于其它类型的SPI膜(＜30 h);由于2,2'-BSBB的刚性结构和大的侧链基团,Ⅱ膜具有较高的质子导电率;Ⅱa-80的质子导电率在20℃条件下为0.112 S/cm,在相同测试条件下,大于Nafion 117的0.09 S/cm,也远远大于相似IEC值的Ic-70的0.044 S/cm.因此,该膜有望作为一种新型的性能优良的质子传输膜材料应用于燃料电池.     

化学稳定的磺化聚酰亚胺质子交换膜的合成及其表征

质子交换膜存在的最大问题是膜的水稳定性问题（包括水解稳定性、尺寸稳定性和溶解稳定性），对于磺化聚酰亚胺膜来说，由于存在酰亚胺环，因此他最大的问题是水解稳定性问题。基于这些问题，本文合成了一系列的化学稳定的（水、氧化和热稳定）磺化聚酰亚胺用做质子交换膜材料，所有的聚合物都表现出良好的成膜性、机械性能和热稳定性。首先，联萘二酐（BTDA）的引入，大大的提高膜的水解稳定性，例如Ⅰa-90在90℃的水中1000h还能保持原有的机械性能，而以NTDA为基础的膜24h就失去了原有的机械性能。同时，在分子链中引入碱性的二胺基团，例如，苯并咪唑等；碱性的基团和磺酸基团形成聚合物盐，增强了分子链间的相互作用，降低了膜的吸水率，提高了尺寸稳定性。例如Ⅰa-90和Ⅰc-90具有相近的IEC值，但是由于聚合物中碱性基团和磺酸形成的分子间作用力，Ⅰa-90的吸水率（65％）低于Ⅰc-90（79％）；吸水率的降低，同时也降低了膜的甲醇透过率。在保持这些优良性能的同时，为了提高膜的氧化稳定性和质子导电率，以新型的全芳香结构的磺化二胺（2，2′-BSBB）合成了一系列的不同磺化度的磺化聚酰亚胺（Ⅱ），所得聚合物具有良好的成膜性，在保持良好的机械性能、高热稳定性等的前提下，由于全芳香磺化二胺的引入，大大的提高了膜的氧化稳定性；尤其是Ⅱa-6^11 0膜，开始溶解的时间大于40h，远大于其它类型的SPI膜（〈30h）；由于2，2′-BSBB的刚性结构和大的侧链基团，Ⅱ膜具有较高的质子导电率；Ⅱa-80的质子导电率在20℃条件下为0．112S／cm，在相同测试条件下，大于Nafion 117的0．09 S／cm，也远远大于相似IEC值的Ⅰc-70的0．044S／cm。因此，该膜有望作为一种新型的性能优良的质子传输膜材料应用于燃料电池。     

磺化聚芳醚砜/磺化聚酰亚胺复合质子交换膜的制备与性能研究

利用溶液浇铸法制备了一系列双磺化型磺化聚芳醚砜/磺化聚酰亚胺(SPAES/SPI)复合质子交换膜.扫描电子显微镜(SEM)结果显示复合膜不存在明显的相分离,表明二者具有很好的相容性.由于SPI的引入,复合膜在甲醇中稳定性较纯SPAES具有大幅的提高,比Nafion112低得多的甲醇吸收率表明了这些复合膜具有比后者更低的甲醇透过率.复合膜显示了与单组分膜相类似的高温分解稳定性,磺酸基团的分解温度达到了290℃以上.复合膜显示出远高于纯SPAES膜的尺寸稳定性能,在130℃高温中200h处理后,所有的复合膜均保持了高的机械性能,而此时纯SPAES膜已经溶解于水中.而且由于两种磺化聚合物间的复合,复合膜维持了较高的IEC水平,显示了较高的质子导电率,在80%相对湿度时的质子导电率与Nafion112相近,而在水中的质子导电率均高于Nafion112.     

新型磺化聚酰亚胺膜的合成与表征

合成了4,4’-二(间氨基苯氧基)联苯-3,3’-二磺酸(mBAPBDS)单体, 采用红外光谱和核磁共振等方法对其结构进行了表征. 使用mBAPBDS, 2-(对胺基苯基)苯并噁唑-5-胺(APBA)和1,4,5,8-萘四甲酸二酐(NTDA)共聚合成了含有噁唑结构的新型磺化聚酰亚胺(NTDA-mBAPBDS/APBA), 通过控制磺化二胺与非磺化二胺的比例来控制磺化程度. NTDA-mBAPBDS/APBA共聚物表现出较好的溶解性、成膜性能和良好的热稳定性, 其磺酸基团分解温度高于300 ℃. 采用溶液浇铸法制备了磺化聚酰亚胺(SPIs)膜, 对膜的吸水率、溶胀度和质子电导率等性能进行了初步的研究. 结果表明, SPIs膜具有适当的吸水率和良好的尺寸稳定性, 其室温电导率在4.72×10－3和9.60×10－3 S/cm之间, 接近于相同条件下Nafion®117的电导率(9.80×10－3 S/cm).     

PTFE辐射接枝对苯乙烯基三甲氧基硅烷制备质子交换膜

采用聚四氟乙烯(PTFE)膜室温下共辐射接枝单体p-苯乙烯基三甲氧基硅烷(StSi),之后经磺化和水解缩聚制备了含有亲水性的—Si—O—Si—交联结构和Si—OH基团的质子交换膜.研究了溶剂、吸收剂量、吸收剂量率以及单体浓度等参数对接枝率的影响,并对质子交换膜的离子交换容量(IEC)、吸水性、尺寸稳定性及电导率等性能进行了分析.结果表明,实验条件下接枝率随吸收剂量和单体浓度增加而增加,采用3mol·L-1的单体浓度减少均聚物;吸收剂量率为10～43Gy·min-1时,接枝率随剂量率变化不明显;以甲苯做溶剂可获得较高接枝率并保持膜的机械强度;IEC值、吸水性和电导率随接枝率增加而增大,是—SO3H、—Si—O—Si—交联结构和Si—OH基团共同作用的结果.接枝率72.5%时膜的IEC值为1.53mmol·g-1,高于Nafion117(0.89mmol·g-1),90℃吸水率为63%,尺寸稳定(优于Nafion117),质子电导率达1.5×10-2S·cm-1,获得了低于Nafion117的甲醇透过性,接枝率50.1%时甲醇透过系数0.82×10-6cm2·s-1.     

非含氟型磺化聚合物质子交换膜材料的研究进展(上)

概述了近十年来非含氟型磺化聚合物质子交换膜材料的研究进展,包括各种材料的制备和性质,详细地讨论了材料的化学结构、形态与其性能(质子导电率、耐水性、尺寸稳定性、吸水率、抗自由基氧化性、甲醇透过率等)之间的关系,其中结合作者在磺化聚酰亚胺方面的研究工作,重点对这类材料进行了系统、深入的介绍和讨论.最后,本文还对今后燃料电池用质子交换膜材料的研究提出了一些设想和展望.本文分为上下两篇,其中上篇主要综述了各种非含氟型磺化聚合物的制备方法.     

非含氟型磺化聚合物质子交换膜材料的研究进展(下)

概述了近十年来非含氟型磺化聚合物质子交换膜材料的研究进展,包括各种材料的制备和性质,详细地讨论了材料的化学结构、形态与其性能(质子导电率、耐水性、尺寸稳定性、吸水率、抗自由基氧化性、甲醇透过率等)之间的关系,其中结合作者在磺化聚酰亚胺方面的研究工作,重点对这类材料进行了系统、深入的介绍和讨论.最后,本文还对今后燃料电池用质子交换膜材料的研究提出了一些设想和展望.本文分为上下两篇,其中下篇主要综述了非含氟型磺化聚合物的性能与结构形态之间的关系.     

侧链磺化型聚砜质子交换膜的设计与制备及其性能研究

在制备氯甲基化聚砜(CMPSF)的基础上,以对羟基苯磺酸钠(HBSS)和羟基苯二磺酸钠(HBDSS)为亲核试剂,通过亲核取代反应,在聚砜(PSF)主链上分别键联了以苯磺酸根(BSS)和苯二磺酸根(BDSS)基团为末端基的侧链,制得了亲水磺酸根基团与疏水主链"微相分离"结构的2种侧链型磺化聚砜PSF-BSS和PSF-BDSS,并优化了制备条件.在对磺化聚砜产物进行充分表征(FTIR和1H-NMR谱)的基础上,采用流延成膜法制备了质子交换膜,测定了质子交换膜的基本性能,重点考察了质子交换膜"芳香性"主链和亲疏水微区"相分离"这2种结构因素对交换膜性能的影响.实验结果表明,在极性较强的溶剂中,CMPSF与羟基苯磺酸钠可顺利地发生亲核取代反应,于100℃经40 h反应可制得磺酸根键合量分别为2.07 mmol/g和2.11 mmol/g的磺化聚砜PSF-BSS和PSF-BDSS.所制备的质子交换薄膜具有较高的质子传导率(PSF-BDSS交换膜室温为4.7×10-2S/cm,80℃为8.1×10-2S/cm),优良的尺寸稳定性(室温溶胀率为8.6%,80℃溶胀率为30%),且具有良好的热稳定性与抗氧化稳定性.     

杂萘联苯聚芳醚质子交换膜材料的研究

质子交换膜是质子交换膜燃料电池的核心部件之一，其性能的优劣直接关系燃料电池的工作性能。目前质子交换膜燃料电池多采用全氟磺酸离子膜，全氟磺酸膜虽然具有较高的质子传导性和良好的化学稳定性，但是也具有价格昂贵、甲醇渗透高和高温下质子传导性能下降等缺点。为了克服全氟磺酸膜的不足，国内外相继开展了非氟质子交换膜的研究，如磺化聚醚醚酮（SPEEK）、磺化聚醚醚酮酮（SPEEKK）、磺化聚砜（SPSU）和磺化聚酰亚胺（SPI）等。     

酸碱型磺化聚芳醚腈酮质子交换膜材料的性能研究

以合成的一系列不同磺化度的碘化聚芳醚腈酮(SPPENKs)为acidic聚合物,以聚芳醚酰亚胺(PEI)为basic聚合物,并将其溶解在N-甲基-2-吡咯烷酮(NMP)中配成质量分数为10%的成膜液,60℃下刮制成膜,制得acid-base型磺化聚芳醚腈酮质子导电了聚合物膜.用红外(FT-IR)谱图表征了acid-base型质子导电聚合物的结构,并测试了acid-base型质子导电聚合物膜的溶胀率、含水率、水解、氧化和热稳定性以及膜材料的离子交换容量IEC(IEC=meqSO3H/gdrymembrane)值等.测试结果初步表明新型质子导电聚合物膜具有良好的物化性能和较高的质子导电性,在80℃下acid-base型质子导电聚合物膜的水解断裂时间除SPPENK-40/PEI外,都超过2000h;SPPENK-60/PEI和SPPENK-80/PEI膜(IEC分别为1·08mmol/g、1·32mmol/g)与Nafion117相比,在具有较高质子交换能力的同时具有较低的溶胀率。     

Characterizations and stability of polyimide-phosphotungstic acid composite electrolyte membranes for fuel cell

Organic-inorganic composite membranes from partially aliphatic sulfonated polyimides and heteropolyacids (HPAs) were synthesized. A series of composite membranes with varying amounts of heteropolyacid were prepared by altering the weight ratio of polyimide and HPA. The partially aliphatic sulfonated polyimides are synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminobiphenyl 2,2′-disulfonic acid as the sulfonated diamine, and decamethylenediamine as the aliphatic diamine. The incorporation of HPA is confirmed by FT-IR analyses. When appropriately embedded in a hydrophilic polymer matrix, the hydrated HPAs are expected to endow the composite membrane with their high proton conductivity, while retaining the desirable mechanical properties of the polymer film. These composite membranes were evaluated for thermal stability, ion exchange capacity, water uptake and proton conductivity. Also the extraction of HPA from the polyimide membranes and their stability in water were determined. Though water uptake and IEC decreased with increase in HPA content, the proton conductivity of the composite membranes increased with increase in HPA weight content. This study shows that partially aliphatic sulfonated polyimide composite membranes with HPA can be a viable substitute for Nafion^® for fuel cells which show good conductivity comparable to Nafion^®117 at temperatures nearing 100 °C, keeping in mind that polyimides have good thermal stability and low cost.     

Investigating the proton transferring route in a heteroaromatic compound part I: a trial to develop di- and trifunctional benzimidazole model compounds inducing the molecular packing structure with a hydrogen bond network

Di- and trifunctional benzimidazole molecules, 1 and 2, have been synthesized as the model compounds to identify their molecular packing structure and hydrogen bond network, which is possibly involved in the proton transfer system belonging to its heteroaromatic functional groups. By carrying out the simple reaction between acid chloride and diamine, the desired benzimidazole model compounds are obtained with high yield above 60%. The comparison studies between the model compounds and benzimidazole reveal that the model compounds show well-packing structure with intermolecular hydrogen bonds similar to those observed in benzimidazole. The presence of solvent with 2 leads to the unique intermolecular hydrogen bonds between one molecule of 2 and six molecules of solvent (i.e., 2-propanol) resulting in the solvent-assisted intramolecular hydrogen bond network among benzimidazole functional groups. The comparative studies of the effect of temperature on the packing structure and hydrogen bond in the model compounds indicate that the development of the benzimidazole unit from monofunctional to difunctional and finally trifunctional enhances the intermolecular interaction between the molecules and results in the stronger molecular packing structure of the compounds. A study on proton conductivity by preparing the sulfonated poly(ether ether ketone) (SPEEK) membranes with benzimidazole, 1, and 2 for 15 phr equivalent to benzimidazole group clarifies (i) incorporation of benzimidazole compounds improves the proton conductivity of SPEEK in dry condition and (ii) the increase in proton conductivity is relevant to the number of benzimidazole group on molecule.     

支化型聚苯并咪唑高温质子交换膜的制备与性能研究

通过引入1,3,5-苯三酸作为支化结构,制备了一种新型的支化型聚醚聚苯并咪唑(OPBI)高温燃料电池质子交换膜,并对支化OPBI质子交换膜的磷酸掺杂率、抗氧化稳定性、机械性能以及质子传导率等一系列性质进行了深入研究.与线型聚苯并咪唑(PBI)相比,支化OPBI具有独特的三维空间结构,极大地提高了磷酸掺杂量,随着支化度的提高,磷酸掺杂率和质子传导率随之提高.支化度为9%时,聚合物的磷酸掺杂率高达9.2 PRU?1,质子传导率达到0.0314 S/cm.此外,支化OPBI膜的溶解性较线型PBI也有较大的改善,进一步提高了聚合物的可加工性.同时,支化OPBI膜的热稳定性和抗氧化稳定性也得到了一定程度的提高,虽然机械性能略有下降,但仍能满足高温燃料电池的使用要求.     

Sulfonated polybenzimidazoles: Proton conduction and acid–base crosslinking

A series of soluble, benzimidazole‐based polymers containing sulfonic acid groups (SuPBI) has been synthesized. SuPBI membranes resist extensive swelling in water but are poor proton conductors. When blended with high ion exchange capacity (IEC) sulfonated poly(ether ether ketone) (SPEEK), a polymer that has high proton conductivity but poor mechanical integrity, ionic crosslinks form reducing the extent of swelling. The effect of sulfonation of PBI on crosslinking in these blends was gauged through comparison with nonsulfonated analogs. Sulfonic acid groups present in SuPBI compensate for acid groups involved in crosslinking, thereby increasing IEC and proton conductivity of the membrane. When water uptake and proton conductivity were compared to the IEC of blends containing either sulfonated or nonsulfonated PBI, no noticeable distinction between PBI types could be made. Comparisons were also made between these blends and pure SPEEK membranes of similar IEC. Blend membranes exhibit slightly lower maximum proton conductivity than pure SPEEK membranes (60 vs. 75 mS cm^?1) but had significantly enhanced dimensional stability upon immersion in water, especially at elevated temperature (80 °C). Elevated temperature measurements in humid environments show increased proton conductivity of the SuPBI membranes when compared with SPEEK‐only membranes of similar IEC (c.f. 55 for the blend vs. 42 mS cm^?1 for SPEEK at 80 °C, 90% relative humidity). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3640–3650, 2010     

Synthesis and properties of sulfonated polyimides derived from bis(sulfophenoxy) benzidines

A series of aromatic sulfonated polyimides (SPIs) bearing sulfophenoxy side groups have been successfully synthesized and evaluated as polymer electrolyte membranes for fuel cell applications. The SPIs had high viscosity and gave tough and flexible membranes. The SPI membranes showed anisotropic membrane swelling in water with much larger dimensional change in thickness direction than in plane one. They showed the better proton‐conducting performance even in the lower relative humidity (RH) range than the other SPI membranes, for example, a high proton conductivity of 0.05 S/cm at 50 % RH and 120 °C. They maintained high mechanical strength and conductivity after aging in water at 130 °C for 500 h, showing much better water stability compared with the main‐chain‐type SPI and side‐chain‐type SPI membranes reported so far. In polymer electrolyte fuel cells (PEFCs) operated at 90 °C and 84–30%RH, they showed fairly high cell performances and have high potential for PEFC applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1463–1477, 2009     

Nanostructured Proton-Conducting Membranes for Fuel Cell Applications

Summary: Composite polymer membranes based on sulfonated poly(arylene ether sulfone) (SPSU) containing benzimidazole derivatives (BIzD) and heteropolyacid for use in fuel cells were prepared. The effects of both the increment in BBIzD component and the procedure of mixing on the morphology and proton conductivity were investigated. The heteropolyacid (HPA) extracted in water decreased with the addition of BBIzD in the composite. The interactions developed among the sulfonate groups, the benzimidazole derivatives and the HPA were verified by Fourier transform infrared (FTIR). The network of interactions established in the composite membrane based on SPSU containing benzimidazole derivatives and phosphotungstic acid (HPW) in the ratio of SPSU/BBIzC₄(8:1) in equivalents and SPSU/HPW(7:3) in mass resulted in a very high proton conductivity at 110 °C.     

Synthesis and characterization of thermally stable,high‐modulus polyimides containing benzimidazole moieties

A series of novel benzimidazole‐containing aromatic polyimides were prepared from synthesized 5,4′‐diamino‐2‐phenyl benzimidazole (DAPBI), and commercial dianhydrides by the conventional two‐step polymerization. The obtained films were amorphous and could afford flexible, transparent, and tough films with excellent thermal and mechanical properties. They showed high levels of tension strength of up to 234 MPa, modulus of up to 5.6 GPa without any stretching. According to thermal stability measurements, the glass‐transition temperatures of the polymers were observed between 329 and 425 °C. The 5% weight‐loss temperatures of most polyimides were above 600 °C in nitrogen. Excellent properties of these polyimides were proved to be attributed to the rigid‐rod structure and hydrogen bond of intermacromolecular. SAXS and SEM results showed self‐molecular orientation caused the formation of rod‐like extended conformations. It was demonstrated that high degree of supramolecular order led to the increase of thermal stability and mechanical properties of the polyimide films. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2024–2031, 2009     

Synthesis of polyimides with lower H2O-absorption and higher thermal properties by incorporation of intramolecular H-bonding

To introduce intramolecular hydrogen bonds in the polyimides (PIs), 5(6)-amino-2-(5-aminopyridin-2-yl)-benzimidazole (PyPABZ) were designed and synthesized. The intramolecular interaction was indicated by Fourier transform infrared when different copolyimides were prepared with 4,4′-oxydianiline and PyPABZ. These modified poly(benzimidazole imide)s eliminate the problem of high water absorption for benzimidazole (BI)-containing PIs in the materials applications. Moreover, the high packing coefficient and rigidity of these copolyimides caused by the strong intramolecular interaction from the H-bonding and the resulting PIs exhibited outstanding thermal properties such as high glass-transition temperature (T_g) and low coefficient of thermal expansion.     

Structure and properties relationships for aromatic polyimides and their derived carbon membranes: experimental and simulation approaches

The main objective of this study is to investigate the factors of the chemical structure and physical properties of rigid polyimides in determining the performance of derived carbon membranes through both the experimental and simulation methods. Four polyimides made of different dianhydrides were pyrolyzed at 550 and 800 degrees C under vacuum conditions. The resultant carbon membranes exhibit excellent gas separation performances beyond the traditional upper limit line for polymer membranes. The thermal stability and the fractional free volume (FFV) of polyimides were examined by a thermogravimetric analyzer and a density meter. The chain properties of polyimide, such as flatness, chain linearity, and mobility, were simulated using the Cerius(2) software. All above characterizations of polyimides were related to the microstructure and gas transport properties of the resultant carbon membranes. It was observed that the high FFV values and low thermal stability of polyimide produce carbon membranes with bigger pore and higher gas permeability at low pyrolysis temperatures. Therefore, polyimides with big thermally labile side groups should be preferred to prepare carbon membranes at low pyrolysis temperatures for high permeability applications. On the other side, since the flatness and in-plane orientation of precursors may lead carbon membranes to ordered structure, thus obtaining high gas selectivity, linear polyimides with more coplanar aromatic rings should be first choice to prepare carbon membranes at high pyrolysis temperatures for high selectivity applications. The location of the indan group also affects chain flatness and in-plane orientation. As a result, carbon membranes derived from the BTDA-DAI precursor have superior separation performance to those derived from Matrimid.     

Synthesis and characterization of novel sulfonated polyimide containing phthalazinone moieties as PEM for PEMFC

A novel sulfonated diamine monomer,1,2-dihydro-2-(3-sulfonic-4-aminophenyl)-4-[4-(4-aminophenoxy)-phenyl]phthalazin- 1-one(S-DHPZDA),was successfully synthesized by direct sulfonation of diamine 1,2-dihydro-2-(4-aminophenyl)-4-[4-(4- aminophenoxy)-phenyl]-phthalazin-1-one(DHPZDA).A series of sulfonated polyimides(SPIs),which can be used as the material of the proton exchange membrane(PEM)for the proton exchange membrane fuel cell(PEMFC),were prepared from 1,4,5,8- naphthalenetetracarboxylic dianhydride(NTDA),S-DHPZDA,and nonsulfonated diamines DHPZDA.The structure of the monomer and polymers were characterized by FT-IR and~1H NMR.The solubility of the S-DHPZDA-based SPIs has been improved due to the induction of the phthalazione moiety.The SPIs membranes have high thermo-stability,predominant swelling resistance with high ion exchange capacity.