聚苯醚基质子交换膜的制备与表征
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摘要
燃料电池将燃料中的化学能等转化为电能,具有高效、可持续发展和环境友好等特点。以氢为燃料的质子交换膜燃料电池(PEMFC)以其高效、操作简便和应用温度范围广而备受瞩目。质子交换膜是PEMFC的关键部分,它直接影响电池性能与寿命。质子交换膜在PEMFC中有两方面重要的基本功能:燃料与氧化剂的分隔和在阴极和阳极之间传递质子。因此,质子交换膜必须满足下述条件:在燃料电池操作条件下,(1)高质子传导率和低电子电导;(2)良好的热稳定性和化学稳定性;(3)良好的机械性能;(4)低渗透;(5)合适的含水率以保证干湿态的尺寸稳定性;(6)膜表面具有一定的粘弹性可以容易制备膜极堆(MEA);(7)合适的价格。Nafion~(?)等全氟磺酸膜是迄今研究最多且商业应用最多的质子交换膜。这种类似特富龙的结构赋予它具有许多优良的性能,例如高质子电导和良好的化学机械稳定性。但对于其在PEMFC的商业化应用中依然存在许多问题,如渗透较大,价格十分昂贵等。这些缺点限制了全氟磺酸膜的商业应用,促使研究者们寻找新的无氟或者部分氟化的聚合物替代。
热塑性工程材料聚苯醚(PPO)具有良好的热稳定性和化学稳定性,能够进行各种改性并且成膜性能优异。特别的,PPO成本低廉,结构简单,可达极高的离子交换容量。PPO虽然被认为是制备质子交换膜的良好材料,但是目前研究的PPO类质子交换膜仍然存在许多问题,限制了其在燃料电池中的应用。主要问题在于质子电导率较低,仅仅在掺杂无机酸时可达到较好的质子电导率,但其含水率太高且稳定性较差。总之,难以达到质子电导率和溶胀(含水率)两方面的要求。
本论文通过几种不同的方法引入亲水/憎水相平衡或交联结构到高磺化度PPO类聚合物中制备出廉价的质子交换膜,研究内容和主要的结果如下:
1.制备出高磺化度的磺化聚苯醚(SPPO)。通过成膜体系的考察(无添加剂,并且不依赖于溶剂)以及膜结构的探测,发现氢型SPPO在热处理时,会以磺酸基团的自缩合方式发生链内和链间的交联反应。通过对于热处理条件的探索,发现交联的程度可以通过热处理的温度或者时间来得到较好的控制和调节。在适宜的成膜条件下,可以达到较好亲水/疏水平衡结构,合适含量的磺酸基团构成的亲水域传递水合质子,而交联形成的疏水域提供膜的机械稳定性和化学稳定性。最佳成膜条件(以丁氧基乙醇为溶剂,80℃热处理5小时)下的制得的交联膜具有高质子电导率、合适的含水率、低渗透、高水解稳定性以及良好的机械性能。特别的,应用交联膜的电池最大功率密度可达0.893 W/cm~2,而应用Nafion~(?)112的电池仅为0.602 W/cm~2。
2.将SPPO和溴化聚苯醚(BPPO)共混制备质子交换膜。在这种组合中,亲水的SPPO增加膜的电导率和含水率,而疏水的BPPO则提供膜的尺寸稳定性和阻醇性能。通过实验结果发现,当SPPO含量较低或者较高时,共混膜的结构较为均一。当SPPO含量在20 wt%附近时,共混膜存在一个从质子的绝缘体变为导体的渗透临界点。综合考虑,SPPO含量为60～80 wt%的共混膜对于燃料电池的应用比较合适。SPPO含量为80 wt%的共混膜显示出比Nafion~(?)117更好的膜单池性能。并且,用氨水、甲胺、二甲胺和三甲胺处理共混膜,考察了不同胺处理的效果。不同的胺处理由于生成的结构不同以及各个胺的pKb值不同,对于SPPO&BPPO共混膜的性质的改进各不相同。从燃料电池的应用角度来看,二甲胺处理共混膜是一个较好的选择,因为可以引入叔胺基团形成较好的酸碱对结构,促进质子传递,增强热稳定性和控制膜的溶胀。
3.将SPPO与胺丙基三乙氧基硅烷(A1100)混合通过溶剂凝胶过程制备有机无机杂化的酸碱对质子交换膜。通过SEM对于膜的形貌结构的观察,膜中有机组分和无机组分之间的酸碱相互作用减少了硅的聚集问题,使膜的形貌结构更加均一。酸碱对作用和无机硅网络结构改善了膜的热稳定性,均一性和尺寸稳定性,并且使得膜非常柔韧。其中氢型SPPO与15 wt%的A1100制备的杂化膜具有较好的质子电导率0.072 S/cm和低甲醇渗透系数2.2×10~(-7) cm~2/s,其电池功率密度可达0.50 W/cm~2(同样条件下应用Nafion~(?)117的电池的最大功率密度为0.38W/cm~2)。
4.通过对甲基溴化PPO进行异相磺化的方法,成功实现PPO的同时苯环磺化和甲基溴化。这种同一主链上具有亲水基团和疏水基团的结构,以及甲基溴化PPO受热形成的苄基交联和磺化中的副反应砜交联的结构,使得膜具有极低的甲醇渗透系数和溶胀,以及较高的质子电导率。通过对于基膜溴化度和磺化条件的探索,溴化度为60%的BPPO基膜在在50 v%氯磺酸中室温进行1小时的磺化是一个较适宜的成膜条件,所得膜的影响因子Φ为Nafion~(?)117的30倍,其甲醇渗透系数仅为2.64×10~(-8) cm~2/s,有潜力在直接甲醇燃料电池中获得较好的应用。
5.将巯基硅氧烷和胺基硅氧烷引入到磺化BPPO膜中,通过原位溶胶凝胶法制备有机无机杂化膜。巯基硅氧烷可以氧化成磺酸基团,胺基硅氧烷可以与溴甲基反应是有机组分和无机组分之间产生共价键相连。通过对不同硅烷比例的影响的研究,巯基硅氧烷含量为75 wt%时的性能最优,氧化后其电导率为0.06S/cm,含水率为8.71%,甲醇渗透系数为1.55×10~(-7) cm~2/s。通过对于氧化过程的研究,发现膜的氧化主要是由于聚合物侧链的溴基团和磺酸基团的脱落降低了膜的性能。不论在强氧化条件下还是较温和的氧化环境下,无机组分硅氧烷的引入大大改善了杂化膜的氧化稳定性。在80℃Fenton试剂(3 wt%双氧水,4 ppm Fe~(2+))中1小时仍能保持其电导率。
本文的研究结果表明,引入亲水/憎水相平衡和交联结构到高磺化度PPO类聚合物中制备质子交换膜是一种有效的方法。所制得的廉价的质子交换膜在燃料电池的应用中具有较大的潜力。
Fuel cells are known as alternative energy conversion systems with high efficiency,renewable fuel(hydrogen,methanol,etc.),and environmental benignity. Hydrogen Proton exchange membrane fuel cells(PEMFCs) were studied the most extensively due to their high effiency,relatively easy operation,and broad range of operating temperature.As the key component in PEMFCs,proton exchange membranes serve as a barrier for fuel and oxidant with the function of transporting protons and blocking electrons.Accordingly,they should possess(1) high proton conductivity and low electronic conductivity,(2) good thermal and chemical stability, (3) good mechanical properties,(4) low permeability,(5) dimensional stability,(6) capability for facbrication into membrane electrode assemblies,and(7) low cost. Perfluorosulfonic acid polymers like Nation~(R) have some properties good for PEMFC applications and have been the standard membrane for industry and academia during the last decade,but they also have a number of drawbacks,such as high cost and large methanol permeability.These factors have limited its commercial applications;hence, there is a urgent need to explore new proton exchange membranes that can achieve high performance at a low cost.
Poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) is a versatile,thermally stable engineering plastic with high mechanical strength and excellent hydrolytic stability. The structure of PPO is simple as compared to other aromatic polymers and it allows many modifications in both aryl and benzyl positions.Especially,modified PPO could possess high ion exchange capacity and good membrane forming properties.Although PPO was considered a promising material for proton exchange membranes,current studies on PPO has not reported good fuel cell performances.The main problems are low proton conductivity and difficulty in controlling membrane swelling.
Therefore,preparation of proton exchange membranes by introducing hydrophilic/hydrophobic balance and crosslinking structure to highly sulfonated PPO-based polymers become the focus of this research.The preparation routes and results are as follows.
A series of low-cost proton exchange membranes with covalent crosslinking structure were prepared from sulfonated PPO(SPPO) only through a heat treatment. The crosslinking degree could be controlled by adjusting the time or temperature for heat treatment.With a proton conductivity of 0.128 S cm~(-1) and tensile strength of 52.8 MPa,as well as proper water uptake and low crossover,the optimum membrane showed a maxim power density of 0.893 W cm~(-2) while that of Nafion~(R) 112 is 0.602 W cm~(-2) in a single cell test at 60℃.In view of the competitive properties with Nafion~(R) series,the crosslinked membranes are qualified for a potential application in fuel cells.
New composite proton exchange membranes were prepared by mixing SPPO with bromomethylated PPO(BPPO) for hydrophilic-hydrophobic balance.By properly compromising the conductivity and methanol permeability,membranes with 60-80 wt%SPPO content exhibited comparable proton conductivity to that of Nafion~(R) 117,and only half the methanol permeability of Nafion~(R) 117,thereby demonstrating higher single cell performance.The composite was then treated with different amines,such as ammonia,methyl amine,dimethyl amine,and trimethyl amine.These amines have different pKb values and induce distinctive acid-base interactions between aminated BPPO and SPPO.The change in proton conductivity depends on amine type and the SPPO content.Dimethyl amine is recommendable because it can form tertiary ammonium groups to facilitate the proton transfer without appreciable increase in methanol permeability and can form effective acid-base polymer complex with SPPO to increase the thermal stability.
A series of hybrid acid-base polymer membranes were prepared by blending SPPO with(3-aminopropyl) triethoxysilane through a sol-gel process.As indicated by scanning electron microscopy,energy-dispersive X-ray analysis,and thermogravimetric analysis,the acid-base interaction improves not only the membrane homogeneity and thermal stability but also the mechanical strength and flexibility.Apart from the low cost,the developed membranes exhibit high proton conductivity and low methanol permeability as compared to Nafion~(R) 117.Further,the optimal membrane showed better performance than Nafion~(R) 117 in a single cell test. All these properties make the hybrid membranes suitable for application in fuel cells.
For direct methanol fuel cell applications,a series of proton exchange membranes were developed via sulfonation of BPPO base membranes.Besides the low manufacture cost,the membranes exhibited an excellent control on methanol crossover and swelling,and a sound balance with high proton conductivities.These can be attributed to the inherent properties of membrane structures:(ⅰ) benzyl-substitution with bromine,which imparts the membrane stronger hydrophobicity,(ⅱ) cross-linking between BPPO chains,which enhances the dimensional stability and renders the membrane a dense texture,(ⅲ) proper content of sulfonic acid groups,which guarantees high proton conductivities.The optimal membrane exhibited a methanol permeability of 2.64×10~(-8) cm~2 s~(-1) and characteristic factorΦof thirty times higher than that of Nafion~(R) 117.
A series of organic-inorganic hybrid membrane were prepared by introducing mercapto silanes and amino silanes to sulfonated BPPO membranes through in-situ sol-gel.Mercapto groups can be oxidated to sulfonic acid groups to accelerate proton conduction,while amino silanes react with benzyl bromine to connect organic and inorganic components by chemical bones.The hybrid membrane with mercapto silane content of 75 wt%showed the best performance;i.e.,it had a proton conductivity of 0.06 S cm~(-2),water uptake of 8.71%,and methanol permeability of 1.55×10~(-7) cm~2 s~(-1). During oxidation,the deterioration of performance is caused by the decomposition of the sulfonic goup and bromine at the pendant of PPO backbones.The introduction of silanes improves the oxidative stabilility of hybrid membranes in strong or mild oxidative conditions.Its proton conductivity was kept for 1 h even in Fenton agent at 80℃.
In summary,it seems attractive and effective to prepare proton exchange membranes by introducing hydrophilic/hydrophobic balance and crosslinking structure to highly sulfonated PPO-based polymers.The resulting low-cost membranes show a great potential in fuel cell applications.
热塑性工程材料聚苯醚(PPO)具有良好的热稳定性和化学稳定性,能够进行各种改性并且成膜性能优异。特别的,PPO成本低廉,结构简单,可达极高的离子交换容量。PPO虽然被认为是制备质子交换膜的良好材料,但是目前研究的PPO类质子交换膜仍然存在许多问题,限制了其在燃料电池中的应用。主要问题在于质子电导率较低,仅仅在掺杂无机酸时可达到较好的质子电导率,但其含水率太高且稳定性较差。总之,难以达到质子电导率和溶胀(含水率)两方面的要求。
本论文通过几种不同的方法引入亲水/憎水相平衡或交联结构到高磺化度PPO类聚合物中制备出廉价的质子交换膜,研究内容和主要的结果如下:
1.制备出高磺化度的磺化聚苯醚(SPPO)。通过成膜体系的考察(无添加剂,并且不依赖于溶剂)以及膜结构的探测,发现氢型SPPO在热处理时,会以磺酸基团的自缩合方式发生链内和链间的交联反应。通过对于热处理条件的探索,发现交联的程度可以通过热处理的温度或者时间来得到较好的控制和调节。在适宜的成膜条件下,可以达到较好亲水/疏水平衡结构,合适含量的磺酸基团构成的亲水域传递水合质子,而交联形成的疏水域提供膜的机械稳定性和化学稳定性。最佳成膜条件(以丁氧基乙醇为溶剂,80℃热处理5小时)下的制得的交联膜具有高质子电导率、合适的含水率、低渗透、高水解稳定性以及良好的机械性能。特别的,应用交联膜的电池最大功率密度可达0.893 W/cm~2,而应用Nafion~(?)112的电池仅为0.602 W/cm~2。
2.将SPPO和溴化聚苯醚(BPPO)共混制备质子交换膜。在这种组合中,亲水的SPPO增加膜的电导率和含水率,而疏水的BPPO则提供膜的尺寸稳定性和阻醇性能。通过实验结果发现,当SPPO含量较低或者较高时,共混膜的结构较为均一。当SPPO含量在20 wt%附近时,共混膜存在一个从质子的绝缘体变为导体的渗透临界点。综合考虑,SPPO含量为60～80 wt%的共混膜对于燃料电池的应用比较合适。SPPO含量为80 wt%的共混膜显示出比Nafion~(?)117更好的膜单池性能。并且,用氨水、甲胺、二甲胺和三甲胺处理共混膜,考察了不同胺处理的效果。不同的胺处理由于生成的结构不同以及各个胺的pKb值不同,对于SPPO&BPPO共混膜的性质的改进各不相同。从燃料电池的应用角度来看,二甲胺处理共混膜是一个较好的选择,因为可以引入叔胺基团形成较好的酸碱对结构,促进质子传递,增强热稳定性和控制膜的溶胀。
3.将SPPO与胺丙基三乙氧基硅烷(A1100)混合通过溶剂凝胶过程制备有机无机杂化的酸碱对质子交换膜。通过SEM对于膜的形貌结构的观察,膜中有机组分和无机组分之间的酸碱相互作用减少了硅的聚集问题,使膜的形貌结构更加均一。酸碱对作用和无机硅网络结构改善了膜的热稳定性,均一性和尺寸稳定性,并且使得膜非常柔韧。其中氢型SPPO与15 wt%的A1100制备的杂化膜具有较好的质子电导率0.072 S/cm和低甲醇渗透系数2.2×10~(-7) cm~2/s,其电池功率密度可达0.50 W/cm~2(同样条件下应用Nafion~(?)117的电池的最大功率密度为0.38W/cm~2)。
4.通过对甲基溴化PPO进行异相磺化的方法,成功实现PPO的同时苯环磺化和甲基溴化。这种同一主链上具有亲水基团和疏水基团的结构,以及甲基溴化PPO受热形成的苄基交联和磺化中的副反应砜交联的结构,使得膜具有极低的甲醇渗透系数和溶胀,以及较高的质子电导率。通过对于基膜溴化度和磺化条件的探索,溴化度为60%的BPPO基膜在在50 v%氯磺酸中室温进行1小时的磺化是一个较适宜的成膜条件,所得膜的影响因子Φ为Nafion~(?)117的30倍,其甲醇渗透系数仅为2.64×10~(-8) cm~2/s,有潜力在直接甲醇燃料电池中获得较好的应用。
5.将巯基硅氧烷和胺基硅氧烷引入到磺化BPPO膜中,通过原位溶胶凝胶法制备有机无机杂化膜。巯基硅氧烷可以氧化成磺酸基团,胺基硅氧烷可以与溴甲基反应是有机组分和无机组分之间产生共价键相连。通过对不同硅烷比例的影响的研究,巯基硅氧烷含量为75 wt%时的性能最优,氧化后其电导率为0.06S/cm,含水率为8.71%,甲醇渗透系数为1.55×10~(-7) cm~2/s。通过对于氧化过程的研究,发现膜的氧化主要是由于聚合物侧链的溴基团和磺酸基团的脱落降低了膜的性能。不论在强氧化条件下还是较温和的氧化环境下,无机组分硅氧烷的引入大大改善了杂化膜的氧化稳定性。在80℃Fenton试剂(3 wt%双氧水,4 ppm Fe~(2+))中1小时仍能保持其电导率。
本文的研究结果表明,引入亲水/憎水相平衡和交联结构到高磺化度PPO类聚合物中制备质子交换膜是一种有效的方法。所制得的廉价的质子交换膜在燃料电池的应用中具有较大的潜力。
Fuel cells are known as alternative energy conversion systems with high efficiency,renewable fuel(hydrogen,methanol,etc.),and environmental benignity. Hydrogen Proton exchange membrane fuel cells(PEMFCs) were studied the most extensively due to their high effiency,relatively easy operation,and broad range of operating temperature.As the key component in PEMFCs,proton exchange membranes serve as a barrier for fuel and oxidant with the function of transporting protons and blocking electrons.Accordingly,they should possess(1) high proton conductivity and low electronic conductivity,(2) good thermal and chemical stability, (3) good mechanical properties,(4) low permeability,(5) dimensional stability,(6) capability for facbrication into membrane electrode assemblies,and(7) low cost. Perfluorosulfonic acid polymers like Nation~(R) have some properties good for PEMFC applications and have been the standard membrane for industry and academia during the last decade,but they also have a number of drawbacks,such as high cost and large methanol permeability.These factors have limited its commercial applications;hence, there is a urgent need to explore new proton exchange membranes that can achieve high performance at a low cost.
Poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) is a versatile,thermally stable engineering plastic with high mechanical strength and excellent hydrolytic stability. The structure of PPO is simple as compared to other aromatic polymers and it allows many modifications in both aryl and benzyl positions.Especially,modified PPO could possess high ion exchange capacity and good membrane forming properties.Although PPO was considered a promising material for proton exchange membranes,current studies on PPO has not reported good fuel cell performances.The main problems are low proton conductivity and difficulty in controlling membrane swelling.
Therefore,preparation of proton exchange membranes by introducing hydrophilic/hydrophobic balance and crosslinking structure to highly sulfonated PPO-based polymers become the focus of this research.The preparation routes and results are as follows.
A series of low-cost proton exchange membranes with covalent crosslinking structure were prepared from sulfonated PPO(SPPO) only through a heat treatment. The crosslinking degree could be controlled by adjusting the time or temperature for heat treatment.With a proton conductivity of 0.128 S cm~(-1) and tensile strength of 52.8 MPa,as well as proper water uptake and low crossover,the optimum membrane showed a maxim power density of 0.893 W cm~(-2) while that of Nafion~(R) 112 is 0.602 W cm~(-2) in a single cell test at 60℃.In view of the competitive properties with Nafion~(R) series,the crosslinked membranes are qualified for a potential application in fuel cells.
New composite proton exchange membranes were prepared by mixing SPPO with bromomethylated PPO(BPPO) for hydrophilic-hydrophobic balance.By properly compromising the conductivity and methanol permeability,membranes with 60-80 wt%SPPO content exhibited comparable proton conductivity to that of Nafion~(R) 117,and only half the methanol permeability of Nafion~(R) 117,thereby demonstrating higher single cell performance.The composite was then treated with different amines,such as ammonia,methyl amine,dimethyl amine,and trimethyl amine.These amines have different pKb values and induce distinctive acid-base interactions between aminated BPPO and SPPO.The change in proton conductivity depends on amine type and the SPPO content.Dimethyl amine is recommendable because it can form tertiary ammonium groups to facilitate the proton transfer without appreciable increase in methanol permeability and can form effective acid-base polymer complex with SPPO to increase the thermal stability.
A series of hybrid acid-base polymer membranes were prepared by blending SPPO with(3-aminopropyl) triethoxysilane through a sol-gel process.As indicated by scanning electron microscopy,energy-dispersive X-ray analysis,and thermogravimetric analysis,the acid-base interaction improves not only the membrane homogeneity and thermal stability but also the mechanical strength and flexibility.Apart from the low cost,the developed membranes exhibit high proton conductivity and low methanol permeability as compared to Nafion~(R) 117.Further,the optimal membrane showed better performance than Nafion~(R) 117 in a single cell test. All these properties make the hybrid membranes suitable for application in fuel cells.
For direct methanol fuel cell applications,a series of proton exchange membranes were developed via sulfonation of BPPO base membranes.Besides the low manufacture cost,the membranes exhibited an excellent control on methanol crossover and swelling,and a sound balance with high proton conductivities.These can be attributed to the inherent properties of membrane structures:(ⅰ) benzyl-substitution with bromine,which imparts the membrane stronger hydrophobicity,(ⅱ) cross-linking between BPPO chains,which enhances the dimensional stability and renders the membrane a dense texture,(ⅲ) proper content of sulfonic acid groups,which guarantees high proton conductivities.The optimal membrane exhibited a methanol permeability of 2.64×10~(-8) cm~2 s~(-1) and characteristic factorΦof thirty times higher than that of Nafion~(R) 117.
A series of organic-inorganic hybrid membrane were prepared by introducing mercapto silanes and amino silanes to sulfonated BPPO membranes through in-situ sol-gel.Mercapto groups can be oxidated to sulfonic acid groups to accelerate proton conduction,while amino silanes react with benzyl bromine to connect organic and inorganic components by chemical bones.The hybrid membrane with mercapto silane content of 75 wt%showed the best performance;i.e.,it had a proton conductivity of 0.06 S cm~(-2),water uptake of 8.71%,and methanol permeability of 1.55×10~(-7) cm~2 s~(-1). During oxidation,the deterioration of performance is caused by the decomposition of the sulfonic goup and bromine at the pendant of PPO backbones.The introduction of silanes improves the oxidative stabilility of hybrid membranes in strong or mild oxidative conditions.Its proton conductivity was kept for 1 h even in Fenton agent at 80℃.
In summary,it seems attractive and effective to prepare proton exchange membranes by introducing hydrophilic/hydrophobic balance and crosslinking structure to highly sulfonated PPO-based polymers.The resulting low-cost membranes show a great potential in fuel cell applications.
引文
衣宝廉.2004.燃料电池——原理技术应用[M].北京:化学工业出版社
Acosta JL,Fierro JLG,Linares A,Casanova MJ.2000.Characterization of polymer systems based on sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)[J].Polymer International,49(11):1534-1538
Alberti G,Casciola M,Massinelli L,Bauer B.2001.Polymeric proton conducting membranes for medium temperature fuel cells(110-160 degrees C)[J].Journal of Membrane Science,185(1):73-81
Aycock DF,Ting SP.1985.Functionalized polyphenylene ethers and blends with polyamides:U.S.4824915[P].
Becker W,Schmidt-Naake G.2002.Proton exchange membranes by irradiation induced grafting of styrene onto FEP and ETFE:Influences of the crosslinker N,N,-methylene-bis-acrylamide[J].Chemical Engineering & Technology,25(4):373-377
Bhole YS,Kharul UK,Somani SP,Kumbharkar SC.2005.Benzoylation of polyphenylene oxide:Characterization and gas permeability investigations[J].European Polymer Journal,41(10):2461-2471
Bobeson LM,Matzner M.1983.Flame retardant polyarylate compositions U.S.4380598[P].
Bopp R,Gaur U,Kambour R,Wunderlich B.1982.Effect of bromination on the thermal-properties of poly(2,6-dimethyl-1,4-phenylene oxide)[J].Journal of Thermal Analysis,25(2):243-258
Borup R,Meyers J,Pivovar B,Kim YS,Mukundan R,et al.2007.Scientific aspects of polymer electrolyte fuel cell durability and degradation[J].Chemical Reviews,107(10):3904-3951
Bouzek K,Moravcova S,Samec Z,Schauer J.2003.H+ and Na+ ion transport properties of sulfonated poly(2,6-dimethyl-1,4-phenyleneoxide) membranes[J].Journal of the Electrochemical Society,150(6):E329-E336
Buchi FN,Gupta B,Haas O,Scherer GG.1995.Study of Radiation-Grafted Fep-G-Polystyrene Membranes as Polymer Electrolytes in Fuel-Cells[J].Electrochimica Acta,40(3):345-353
Canovas M J,Acosta JL,Linares A.2005.Polymer thermoplastic proton conductors based on PPO and PS ionomer blends[J].Macromolecular Chemistry and Physics,206(6):680-688
Carrette L,Friedrich KA,Stimming U.2000.Fuel cells:Principles,types,fuels,and applications[J].Chemphyschem,1(4):162-193
Chalk A,Hay A.1969.Direct metalation of poly(2,6-dimethyl-1,4-phenylene ether)[J].Journal of
Acosta JL,Fierro JLG,Linares A,Casanova MJ.2000.Characterization of polymer systems based on sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)[J].Polymer International,49(11):1534-1538
Alberti G,Casciola M,Massinelli L,Bauer B.2001.Polymeric proton conducting membranes for medium temperature fuel cells(110-160 degrees C)[J].Journal of Membrane Science,185(1):73-81
Aycock DF,Ting SP.1985.Functionalized polyphenylene ethers and blends with polyamides:U.S.4824915[P].
Becker W,Schmidt-Naake G.2002.Proton exchange membranes by irradiation induced grafting of styrene onto FEP and ETFE:Influences of the crosslinker N,N,-methylene-bis-acrylamide[J].Chemical Engineering & Technology,25(4):373-377
Bhole YS,Kharul UK,Somani SP,Kumbharkar SC.2005.Benzoylation of polyphenylene oxide:Characterization and gas permeability investigations[J].European Polymer Journal,41(10):2461-2471
Bobeson LM,Matzner M.1983.Flame retardant polyarylate compositions U.S.4380598[P].
Bopp R,Gaur U,Kambour R,Wunderlich B.1982.Effect of bromination on the thermal-properties of poly(2,6-dimethyl-1,4-phenylene oxide)[J].Journal of Thermal Analysis,25(2):243-258
Borup R,Meyers J,Pivovar B,Kim YS,Mukundan R,et al.2007.Scientific aspects of polymer electrolyte fuel cell durability and degradation[J].Chemical Reviews,107(10):3904-3951
Bouzek K,Moravcova S,Samec Z,Schauer J.2003.H+ and Na+ ion transport properties of sulfonated poly(2,6-dimethyl-1,4-phenyleneoxide) membranes[J].Journal of the Electrochemical Society,150(6):E329-E336
Buchi FN,Gupta B,Haas O,Scherer GG.1995.Study of Radiation-Grafted Fep-G-Polystyrene Membranes as Polymer Electrolytes in Fuel-Cells[J].Electrochimica Acta,40(3):345-353
Canovas M J,Acosta JL,Linares A.2005.Polymer thermoplastic proton conductors based on PPO and PS ionomer blends[J].Macromolecular Chemistry and Physics,206(6):680-688
Carrette L,Friedrich KA,Stimming U.2000.Fuel cells:Principles,types,fuels,and applications[J].Chemphyschem,1(4):162-193
Chalk A,Hay A.1969.Direct metalation of poly(2,6-dimethyl-1,4-phenylene ether)[J].Journal of