Proton-conducting membranes from phosphotungstic acid-doped sulfonated polyimide for direct methanol fuel cell applications

A series of novel hybrid proton conducting membranes based on sulfonated naphthalimides and phosphotungstic acid (PTA) were prepared from N-Methyl Pyrrolidone (NMP) solutions. These hybrid organic-inorganic materials, composed of two proton-conducting components, have high ionic conductivities (9.3 × 10^?2 S cm^?1 at 60 °C, 15% PTA), and show good performance in H₂|O₂ polymer electrolyte membrane fuel cells (PEMFC), previously reported by us. Moreover, they have low methanol permeability compared to Nafion^®112. In this paper we describe, for the first time, the behaviour of these hybrid membranes as electrolyte in a direct methanol fuel cell (DMFC). The maximum power densities achieved with PTA doped sulfonated naphthalimide membrane, operating with oxygen and air, were 34.0 and 12.2 mW cm^?2, respectively; about the double and triple higher than those showed by the non-doped membrane at 60 °C.     

Synthesis,characterization, and properties of new siloxane grafted copolyimides

Three new siloxane containing grafted copolyimides have been prepared by one‐pot solution imidization technique. The polymers are made by the reaction of 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) with commercially available diamine 4,4′‐oxydianiline (ODA) with variation of silicon containing diamine, namely 3,5‐diaminobenzoate terminated polydimethylsiloxane (DBPDMS), as a comonomer to 10, 20, and 30 wt %. The films of the polymers were prepared by casting the polymer solution in dichloromethane. The polymers have been well‐characterized by GPC, IR, and NMR techniques. Thermal stabilities and decomposition behavior of the copolyimides were studied by DSC and TGA. The water contact angle values of the films indicate hydrophobic nature of the polymers. Thermal, flame retardant, mechanical, and surface properties of these polymers have been compared with the homopolyimide and with polyimides where polysiloxane is incorporated in the main chain. DSC revealed melting of the grafted siloxane chain at sub‐ambient temperature and a glass transition corresponding to the main polymer chain above 200°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

离子液体的合成与应用

离子液体即在常温及附近温度下为液体的离子物质,已合成的主子液体已达上百种,离子液体的合成方法有复分解法和中和法,其应用研究领域有分离过程,化学反应特别是催化反应以及电化学等方面。     

酸性离子液体[SO_3H-Bmim]HSO_4作电解质的甲醇燃料电池性能研究

采用两步法合成了1-磺酸丁基-3甲基咪唑硫酸氢盐([SO_3H-Bmim]HSO_4)酸性离子液体,对其红外光谱结构和电导率进行表征;同时采用不锈钢材料制作了燃料电池的壳体,并制备了阳极和阴极材料,与[SO_3H-Bmim]HSO_4电解质一起组装成燃料单电池。以甲醇为燃料、空气为氧源在80℃采用伏安法测定了燃料电池的性能,其功率密度达到0.19 m W·cm~(-2),有望为甲醇燃料电池实际利用开辟新途径。     

Imidazolium ionic liquid incorporation on sulfonated poly(styrene‐isobutylene‐styrene) proton exchange membranes

Ionic liquids (ILs) with different anions and cations were incorporated in sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) to modify its chemical, morphological, and transport properties for direct methanol fuel cell (DMFC) applications. Different loadings of IL and different solvents were studied to have a better understanding of the incorporation process and the ability of the solvent to affect the interaction of the IL with the sulfonated polymer. Morphological characterization with SAXS and AFM suggested changes caused by the incorporation of the IL and by the solvent used. FT‐IR spectra showed small variations in energy related to interactions of the IL with the sulfonic groups which caused thermogravimetric stabilization of the ionic domains. Other results suggest that water has a very significant effect on the morphology, interaction with the IL, and transport properties of the membranes. Optimal concentration of IL (～10 mol %) provides enough water to produce efficient proton conductivity (0.15 S/cm) and minimal methanol permeability (0.8 × 10^?6 cm²/s). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44900.     

Synthesis and properties of novel sulfonated polyimides bearing sulfophenyl pendant groups for fuel cell application

A novel sulfonated diamine bearing sulfophenyl pendant groups, namely, 4,4′-bis (4-aminophenoxy)-3,3′-bis(4-sulfophenyl) biphenyl and a series of sulfonated polyimides (SPIs) based on it were successfully synthesized. The SPIs had high viscosity and gave tough, flexible and transparent membranes. The SPI membranes showed anisotropic membrane swelling in water with 2.5-4 times larger swelling in thickness direction than in plane one. They displayed reasonably high proton conductivity. For example, the conductivities for the SPI with an ion exchange capacity of 1.80 mequiv/g were 104 and 7.3 mS/cm in water and 50% RH, respectively, at 60 °C. They maintained high mechanical strength and proton conductivity even after aging in water at 130 °C for 500 h, showing the high water stability comparable to the best SPI reported so far. In polymer electrolyte fuel cells (PEFCs) operated at 90 °C and 50% RH, they showed fairly high cell performances and have high potential for PEFC applications.     

离子液体表面活性剂的合成与应用(Ⅱ)——离子液体表面活性剂的合成

按照离子液体表面活性剂的种类,分别介绍了不同类型离子液体表面活性剂的合成方法。阳离子型离子液体表面活性剂可以采用直接季铵化法、复分解法和离子交换法合成;阴离子型离子液体表面活性剂是采用传统阴离子表面活性剂与离子液体在有机溶剂或水/有机溶剂中复分解反应完成的;两性离子液体表面活性剂通常采用直接季铵化法合成;双子和Bola型离子液体表面活性剂与传统双子和Bola型表面活性剂的合成方法相似;微波和超声等新的辅助合成方法将明显促进离子液体表面活性剂的合成。     

双核碱性离子液体的合成及其在阴离子交换膜中的应用

以溴代十二烷、吗啉和1,4-二溴丁烷为原料,通过两步法合成新型氢氧型N-十二烷基双核吗啉离子液体([Nbmd]OH),分别用红外光谱(FTIR)、氢核磁分析(¹H NMR)对合成的离子液体进行结构分析;采用热重(TGA)测试离子液体的热稳定性,同时测定了离子液体的溶解性和碱性.此外,以季铵化壳聚糖(QCS)为制膜原料,碱性离子液体[Nbmd]OH为掺杂物,通过溶液浇铸法制备了一系列掺杂碱性离子液体([Nbmd]OH)的交联复合膜(QCS/[Nbmd]OH).并采用FTIR、TGA、SEM对复合膜的结构、热稳定性和微观形貌进行分析,同时考察离子液体加入量对QCS/[Nbmd]OH复合膜的含水率、机械强度及导电性能等指标的影响.结果表明:随着离子液体含量的增加,QCS/[Nbmd]OH复合膜的含水率、溶胀度、电导率增加,力学性能下降.当离子液体掺杂质量分数为30%时,复合膜在70℃下的电导率为1.17×10^-2S/cm,拉伸强度为11.8 MPa,含水率和溶胀度分别为320%和236%.     

Preparation and characterization of new anhydrous, conducting membranes based on composites of ionic liquid trifluoroacetic propylamine and polymers of sulfonated poly (ether ether) ketone or polyvinylidenefluoride

A novel ionic liquid of trifluoroacetic propylamine, i.e., [CH₃CH₂CH₂NH₃⁺] [CF₃COO⁻] (TFAPA), was synthesized from trifluoroacetic acid and propylamine. The ionic liquid of TFAPA was used to prepare anhydrous, conducting membranes based on polymers of sulfonated poly (ether ether) ketone (SPEEK) or polyvinylidenefluoride (PVDF). The ionic conductivity and mechanical strength of the composite membranes were investigated at elevated temperatures and under anhydrous conditions. Conductivity of 0.030 S/cm was achieved with TFAPA at 180 °C, and of 0.019 S/cm with a membrane containing 70% (wt) TFAPA in SPEEK with a sulfonation degree of 86% at 160 °C. Increasing either ionic liquid content or temperature reduced the mechanical strength of the composite membrane. Efforts were made to improve the strength of TFAPA/SPEEK composite membranes by cross-linking the SPEEK, which led to some strength enhancement at 110 °C and 130 °C.     

燃料电池用密封胶

有机硅橡胶一直以来都用来做燃料电池的密封材料,但有机硅透气性高,不适合氢气、氧气等高透过性气体的密封。三键公司经过多年的潜心研究,成功开发出以聚异丁烯为基材的低透气性密封胶。本文主要介绍燃料电池概念、构造、对密封的要求、泄漏机理以及开发的新型密封胶性能。     

Ex situ hydrolytic degradation of sulfonated polyimide membranes for fuel cells

Ex situ hydrolytic stability of sulfonated polyimide (s-PI) membranes for fuel cells was studied depending on structural and external parameters including the ion exchange capacity, the block character, the temperature and the hydrogen peroxide concentration. Infrared spectroscopy was used to identify and quantify the chemical modifications such as the loss of imide functions and of ionic monomers. The decrease in ion exchange capacity due to the elution of sulfonated oligomers was confirmed by sulfur content analysis. A complete hydrolysis of some of the imide functions is observed leading to polymer chain scissions and to the loss of the mechanical properties. It is shown to be a thermo activated process and the activation energy (60 kJ/mol) is found in good agreement with the value determined from fuel cell lifetimes. The degradation in fuel cell conditions is similar but faster than in pure water. The same kinetic can be reproduced ex situ by addition 0.05% of hydrogen peroxide.     

Investigation on the Preparation of New Sulfonated Polyimide Fuel Cell Membranes in Organic and Ionic Liquid Media

A new sulfonated and an unsulfonated diamine were prepared. These diamines together with 4,4′-oxydianiline and 1,8-diamino-3,6-dioxaoctane were used for preparation of new sulfonated copolyimides (SPIs). Different ratios of sulfonated and unsulfonated diamines were reacted with 1,4,5,8-naphthalene tetracarboxylic dianhydride to prepare SPIs with controlled degrees of sulfonation. These copolyimides were prepared via two different routes: high-temperature polycondensation reaction in m-cresol in the presence of catalyst, and in ionic liquid medium without any catalyst. Copolyimides prepared in ionic liquid medium showed superior properties in comparison to preparation in common solvent method. Polymers revealed promising properties for application in fuel cell.     

用离子液体脱除燃料油中有机硫化物的研究

以咪唑类离子液体作为萃取脱硫剂,在正辛烷和甲苯的混合溶液中加入少量的噻吩构成油品模拟体系。采用正交实验,系统考察了单级萃取中温度、时间、剂油比以及离子液体碳数对脱硫效率的影响,得到了较优的脱硫条件:温度约60℃、萃取时间约40 min、剂油比为1∶1、侧链碳数为10。考察了多级脱硫效率以及离子液体的回收利用。结果表明,经过5级脱硫后,燃料油含硫可以达到欧Ⅲ标准,离子液体重复使用5次后,脱硫效率约降低了2%。回归得到了模拟油品中脱除噻吩的萃取动力学方程。该研究为基于离子液体的燃料油脱硫工艺提供了重要的基础。     

高温质子交换膜燃料电池用离子液体聚合物电解质的研究进展

综述了近十几年来高温质子交换膜燃料电池用离子液体聚合物电解质的研究进展及其在高温质子交换膜燃料电池中的应用进展,指出了此类电解质目前存在的亟待解决的两个问题：咪唑类离子液体毒化Pt基催化剂和复合膜中离子液体的长期稳定性。最后对高温质子交换膜燃料电池用离子液体聚合物电解质的发展前景作了展望,即开发与Pt基催化剂相容的离子液体聚合物电解质以及预防复合膜内离子液体的流失,即提高高温质子交换膜燃料电池的性能及长期稳定性,最终提高高温燃料电池的寿命。     

Biocatalytic ester synthesis in ionic liquid media

Ionic liquids have shown potential as green reaction media compared with organic solvents, mainly due to their lack of vapour pressure. In non‐aqueous enzymology, ionic liquids are opening up new fields. The advantages of using ionic liquids over the use of organic solvents as reaction medium for biocatalysis include enhancement of enzyme activity, stability and selectivity. In this work, the enzymatic synthesis of esters in ionic liquids has been extensively reviewed. Numerous examples of the application of ionic liquids as reaction medium for the enzymatic production of esters have been included. The effect of the nature of the ionic liquid on activity, selectivity and stability of enzymes which catalyze esters synthesis has been carefully analysed. Innovative reaction methodologies for the biosynthesis of esters, including ionic liquid/supercritical carbon dioxide biphasic systems and the integrated reaction/separation processes using supported liquid membranes based on ionic liquids have been revised. Copyright © 2010 Society of Chemical Industry     

新型碱性离子液体催化蓖麻油制备生物柴油

合成了新型碱性离子液体[Bmim]OH,将其应用于催化蓖麻油制备生物柴油,并与催化剂KOH、四丁基氢氧化铵进行比较,结果好于后两者。正交实验优化的碱性离子液体[Bmim]OH催化工艺条件为:催化剂用量为1%,醇油摩尔比为6∶1,反应温度为40℃,反应时间为60 min。在该优化条件下,甲酯混合物收率高于97%,蓖麻油基本上完全转化,其中高于95%转化为产物甲酯,催化剂[Bmim]OH重复使用6次没有明显消耗,催化性能稳定。     

离子液体二氧化碳分离膜研究进展

离子液体支撑液膜在较大跨膜压差（0.25～0.3MPa）下的稳定性较差,具有较好稳定性的聚离子液体膜和离子液体-聚合物共混膜等逐渐被关注。本文综述了离子液体支撑液膜、聚离子液体膜、离子液体?聚合物共混膜等离子液体膜CO2分离性能、分离机理及稳定性的最新研究进展,介绍了无机颗粒-离子液体-聚合物共混膜的研究现状。指出离子液体膜的高CO2渗透通量与高稳定性之间的矛盾、共混膜结构调控难等问题是其工业化应用的主要障碍,提出开发新的膜材料、改进制膜工艺以减小膜厚、优化膜结构是提高膜的CO2渗透和分离性能,并保持膜稳定性的有效途径。无机颗粒-离子液体-聚合物共混膜兼有较高的CO2分离性能和较好稳定性,具有良好的应用前景,对其制备方法、结构、性能及CO2分离机理的研究将成为这一领域的热点。     

离子液体表面活性剂的合成与应用(I)——离子液体表面活性剂的结构和分类

在介绍了离子液体的结构特点和特性的基础上,重点综述了离子液体表面活性剂的结构特征,并且按阳离子型、阴离子型、两性型、双子型和Bola型五类分别介绍了离子液体表面活性剂的典型结构和文献发表的主要品种,显示了离子液体表面活性剂具有较强的结构可设计性和未来品种的多样性。     

离子液体表面活性剂的合成与应用(XII)——微乳液

离子液体表面活性剂替代传统表面活性剂构建微乳液具有明显的优势,且结构可设计;所制备的微乳液分为单相微乳液和多相微乳液,其相图主要包括拟三元相图和“鱼状”相图;微乳液的微观结构,如液滴尺寸、相互作用或极性等,可通过电化学技术、动态激光散射、小角X射线散射等技术来确定。此类微乳液可广泛应用于纳米粒子制备、聚合反应、金属离子萃取等领域。