全氟离子交换膜的研究和应用

概述全氟离子交换膜的制备及该膜的微观结构,讨论其在氯碱工业、燃料电池工业上的应用,并探讨全氟离子膜的研究和开发的方向.     

质子交换膜中质子输送过程的模拟

模拟了质子在质子交换膜(PEMs)中的输送过程。根据Nafion等磺化类PEMs的可能结构。借助无规行走模型研究了PEMs中不同组分间质子跃迁距离等参数对质子输送扩散系数的影响。并把从两维体系得到的结果和三维体系的结果进行比较。通过改变不同组分间的跃迁距离分析PEMs体系的变化。结果表明两者模拟结果无大的差别。已有文献表明质子在PEMs中输送是链段运动输送和质子跃迁输送双重作用的结果。二者的贡献大小取决于具体质子导电体系的种类。利用格子重排和无规行走模型研究了这两种机理对质子导电性能的贡献。     

Evaluation of cross-linked gelatin membranes as delivery carriers for retinal sheets

The delivery of intact sheet transplants to the subretinal space can prevent cell loss that is generally associated with the injection of cell suspensions or cell aggregates. The aim of this study was to develop chemically modified gelatin matrices that enhance the delivery efficiency and analyze whether the gelatin membranes cross-linked with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) can be considered as potential carriers for retinal sheets. The characteristics of EDC cross-linked gelatin membranes were determined by mechanical and in vitro degradation tests, melting point measurements, cell proliferation assays, cytokine expression analyses, and tissue delivery studies. Gelatin membranes without cross-linking and glutaraldehyde cross-linked gelatin samples were used for comparison. Results of this study indicated that introduction of cross-links is capable of rendering the gelatin network more stable against mechanical stresses and deformations as well as rapid hydrolysis during intraocular delivery of delicate tissue sheets. In comparison with the glutaraldehyde treated samples, the EDC cross-linked gelatin membranes showed a better degradation profile and a relatively higher cytocompatibility. In addition, after EDC cross-linking, the gelatin matrices having an acceptable melting point could be used for the fabrication of a sandwich-like carrier with a high transfer and encapsulation efficiency. These findings suggest that the cross-linking agent type gives an influence on delivery functionality of gelatin membranes. In summary, the EDC cross-linked gelatin is an ideal candidate for use as a carrier material in retinal sheet delivery applications.     

质子交换膜中质子输送过程的无规行走模拟

模拟了质子在聚合物电解质膜中的输送过程．借助无规行走模型研究了质子交换膜中含水量、酸掺杂量等因素对质子输送扩散系数的影响,本研究所建立的模型利用改变格子上组分的分布来考虑质子交换膜体系的实际变化．已有资料表明质子在膜中输送是链段运动输送和质子跃迁双重作用的结果,二者的贡献大小取决于具体质子导电体系的种类,本模型用格子重组和无规行走描述了这两种贡献．通过定性和半定量的分析比较,模拟结果较好地符合实验得出的结论．     

High temperature proton exchange membranes prepared from epoxycyclohexylethyltrimethoxysilane and amino trimethylene phosphonic acid as anhydrous proton conductors

High temperature anhydrous proton exchange membranes based on phosphonic acid were prepared from epoxycyclohexylethyltrimethoxysilane (EHTMS) and amino trimethylene phosphonic acid (ATMP) by sol–gel process. The structures and properties of membranes with different phosphonic acid content were extensively characterized by FTIR, TG-DSC and XRD. Their proton conductivity under dry condition was also investigated under different temperature. The results show that the proton conductivity of the prepared membranes strongly depends on temperature, and the proton conductivity ranges from 8.81 × 10⁻⁵ S cm⁻¹ at 20 °C to 4.65 × 10⁻² S cm⁻¹ at 140 °C under anhydrous condition. It indicates that the increasing temperature is favorable for congregating of the grafted–PO₃H₂ and increasing of the proton mobility. In addition, from the results of AFM images, it was confirmed that the continuous distribution of phosphonic acid groups is favorable for the formation of the proton transport channel, which can significantly enhance the proton conductivity of the membranes.     

燃料电池用质子交换膜的研究进展

对燃料电池用质子交换膜的研究进展进行了简要的概述,特别是从膜材料角度分类．较详细的介绍了全氟化质子交换膜,部分氟化质子交换膜,接枝、交联、共混型质子交换膜等的特性及最新的研究状况,并对其发展前景进行了探讨．     

Biocompatibility and anti-cracking performance of perfluorocarboxylic acid ionomer membranes for implantable biosensors

Perfluorosulfonate ionomer (PFSI) membranes can be used to protect biosensors in biological environment. Perfluorocarboxylate ionomer (PFCI) has similar structure to PFSI, and is thus expected to be applicable in vivo. In this study, biocompatibility and anti-cracking performance of PFCI membranes were first investigated. Among various kinds of PFCI membranes, the Na⁺-type exhibited best blood compatibility, as evidenced by the human platelet adhesion and hemolysis rate experiments. When cultured on Na⁺-type PFCI membranes, endothelial cells spread and proliferated to colonize the entire surface, indicating good cell adhesion activity of the membranes. The Na⁺-type membranes were also subcutaneously implanted into guinea pigs, whose incisions were healed after operation without significant rejection phenomenon. After incubation in cell culture medium for 12 weeks, PFCI membranes kept intact only with trace amount of calcium phosphate deposition. XRD and SAXS results demonstrated that PFCI membranes possessed higher crystallinity and smaller ion cluster size than PFSI membranes, thereby endowing the membranes with much better anti-cracking performance. The excellent biocompatibility and anti-cracking performance of Na⁺-type PFCI membranes make them promising implantable biomaterials and protective layers in biosensors.     

Optimal environment for glucose oxidase in perfluorosulfonated ionomer membranes: improvement of first-generation biosensors

An optimal environment for glucose oxidase (GOx) in Nafion membranes is achieved using an advanced immobilization protocol based on a nonaqueous immobilization route. Exposure of glucose oxidase to water-organic mixtures with a high (85-95%) content of the organic solvent resulted in stabilization of the enzyme by a membrane-forming polyelectrolyte. Such an optimal environment leads to the highest enzyme specific activity in the resulting membrane, as desired for optimal use of the expensive oxidases. Casting solution containing glucose oxidase and Nafion is completely stable over 5 days in a refrigerator, providing almost absolute reproducibility of GOx-Nafion membranes. A glucose biosensor was prepared by casting the GOx-Nafion membranes over Prussian Blue-modified glassy carbon disk electrodes. The biosensor operated in the FIA mode allows the detection of glucose down to the 0.1 microM level, along with high sensitivity (0.05 A M(-1) cm(-2)), which is only 10 times lower than the sensitivity of the hydrogen peroxide transducer used. A comparison with the recently reported enzyme electrodes based on similar H2O2 transducers (transition metal hexacyanoferrates) shows that the proposed approach displays a dramatic (100-fold) improvement in sensitivity of the resulting biosensor. Combined with the attractive performance of a Prussian Blue-based hydrogen peroxide transducer, the proposed immobilization protocol provides a superior performance for first-generation glucose biosensors in term of sensitivity and detection limits.     

质子交换膜掺杂固体无机质子导体材料的研究进展

主要介绍了目前掺杂质子交换膜用的几种无机质子导体磷酸锆、杂多酸、硫酸氢盐等,并进一步介绍了将这些无机质子导体引入到聚合物中的3种掺杂方法:混合浇铸法、离子-沉淀法和溶胶-凝胶法.重点介绍了国内外掺杂无机固体质子导体的燃料电池用质子交换膜的研究进展.     

Sulfonated polystyrene fiber network-induced hybrid proton exchange membranes

A novel type of hybrid membrane was fabricated by incorporating sulfonated polystyrene (S-PS) electrospun fibers into Nafion for the application in proton exchange membrane fuel cells. With the introduction of S-PS fiber mats, a large amount of sulfonic acid groups in Nafion aggregated onto the interfaces between S-PS fibers and the ionomer matrix, forming continuous pathways for facile proton transport. The resultant hybrid membranes had higher proton conductivities than that of recast Nafion, and the conductivities were controlled by selectively adjusting the fiber diameters. Consequently, hybrid membranes fabricated by ionomers, such as Nafion, incorporated with ionic-conducting nanofibers established a promising strategy for the rational design of high-performance proton exchange membranes.     

磺化聚苯醚-磷酸锆质子交换复合膜的制备与性能研究

采用溶胶-凝胶法将磺化聚苯醚(SPPO)与磷酸锆(ZrP)复合得到质子交换膜,重点考察了ZrP含量对复合膜含水率、溶胀度和质子电导率的影响,采用红外光谱和交流阻抗法表征SPPO-ZrP复合膜的微观结构和质子电导率。结果表明,SPPO-ZrP复合膜含水率和溶胀度都随着ZrP质量分数增加而逐渐减小,当ZrP质量分数为20%时,膜的含水率和溶胀度分别达到18%和2.1%。通过交流阻抗法对质子传导性能的表征结果显示,随ZrP质量分数增加复合膜质子电导率逐渐增大,ZrP质量分数20%的SPPO-ZrP复合膜质子电导率在室温下达到1.6×10-2S/cm。     

磺化聚苯醚-磷酸锆质子交换复合膜的制备与性能研究

开发价格低廉且性能优异的质子交换膜是目前燃料电池研究的热点.采用溶胶-凝胶法将磺化聚苯醚(SPPO)与磷酸锆(ZrP)复合得到质子交换膜,重点考察了ZrP含量对复合膜含水率、溶胀度和质子电导率的影响,采用红外光谱和交流阻抗法表征SPPO-ZrP复合膜的微观结构和质子电导率.结果表明SPPO与ZrP产生相互作用使SPPO结构发生变化.SPPO-ZrP复合膜含水率和溶胀度都随着ZrP质量分数增加而逐渐减小,当ZrP质量分数为20％时,膜的含水率和溶胀度分别达到18％和2.1％.通过交流阻抗法对质子传导性能的表征结果显示,随ZrP质量分数增加复合膜质子电导率逐渐增大,ZrP质量分数20％的SPPO-ZrP复合膜质子电导率在室温下达到1.6×10-2S/cm.     

燃料电池质子交换膜的研究现状

目前燃料电池质子交换膜的研究正引起人们越来越多的关注,质子交换膜是质子交换膜燃料电池的核心组件.较详细地介绍了全氟化质子交换膜,部分氟化质子交换膜,有机/无机纳米复合质子交换膜,新型无氟化质子交换膜的性能及最新研究状况,最后对其发展前景进行了探讨.     

Sugar-branched-cyclodextrins as injectable drug carriers in mice

The purpose of this study was to investigate stable complexation of drug in blood by sugar-branched-beta-cyclodextrins (beta-CDs) such as glucose (glu)- or galactose (gal)-branched-beta-CDs and the pharmacokinetic disposition of drug in sugar-branched-beta-CD complex. Complexation of steroidal drugs in sugar-branched-beta-CDs and their replacement by cholesterol were measured. The complexes of dexamethasone/glucosyl-beta-CDs (dexamethasone/glu-beta-CD or dexamethasone/glu-glu-beta-CD) were not replaced by cholesterol, which is a representative endogenous compound, whereas the complex of dexamethasone/beta-CD was replaced by cholesterol. The same results were obtained in steroidal drugs such as hydrocortisone, triamcinolone, and prednisolone. Thus, the use of glu-beta-CD and glu-glu-beta-CD permitted the stable complexation of the drug in water. Stability constants of dexamethasone/glu-glu-beta-CD and dexamethasone/gal-glu-beta-CD complexes are the same, which means that the sugar moiety of the side chain in beta-CD has little effect on stability constants. After the dexamethasone/gal-glu-beta-CD complex or the dexamethasone/glu-glu-beta-CD complex (dexamethasone: 1 mg/body) was administered intravenously to mice, dexamethasone concentrations in liver tissue and blood were measured. The dexamethasone/gal-glu-beta-CD complex (66.1 +/- 1.7 micrograms as dexamethasone/gram of liver tissue) was distributed to liver tissue significantly more than the dexamethasone/glu-glu-beta-CD (beta-CD) complex (59.9 +/- 1.0 micrograms as dexamethasone/gram of liver) at 30 min after administration (p < .05). Sugar-branched-beta-CD gave a water-soluble and stable complex for dexamethasone and changed the disposition of dexamethasone. Sugar-branched-beta-CDs are potentially excellent carriers for a steroidal injectable formulation.     

燃料电池用质子交换膜的发展方向

从Nafion膜的结构与性能的关系出发，主要分析了含水量、分子结构以及膜的微观结构和酸度对质子电导率的影响，指出了Nafion膜待克服的问题如高温电导率低，甲醇渗透性大，提出了质子交换膜以后的发展方向，包括Nafion膜的修饰与改性，含氟高分子作为主链接枝带有磺酸的支链，有机聚硅氧烷主链接枝烷基磺酸质子交换膜．     

燃料电池用高温质子交换膜的研究进展

燃料电池是一种高效的清洁能源技术,可缓解当今社会面临的能源和环境问题。质子交换膜燃料电池是一种重要的燃料电池类型,质子交换膜是其关键组件,起到传导质子、隔绝电子和阴阳两极的反应物的作用。质子交换膜燃料电池在低温下存在许多难以解决的问题,升高工作温度可以解决这些问题。因此需要开发高温低湿度下工作的膜材料。本文综述了高温质子交换膜的主要类型、制备与改性方法和质子传导机制,指出质子导体掺杂的聚苯并咪唑(PBI)类膜材料在高温低湿度下作为质子交换膜适用的巨大潜力,并探讨了复合PBI高温质子交换膜的制备、掺杂的质子导体类型和性能提升方法。最后本文归纳了高温质子交换膜面临的挑战,并指出了该类材料未来的研究方向,如设计合成新型质子导体、改善PBI抗氧化稳定性、调控膜微观结构来提升性能和开发新型聚合物电解质。     

新型非氟芳环聚合物质子交换膜研究进展

综述了燃料电池用新型非氟芳环聚合物质子交换膜的研究进展,包括磺化芳环主链聚合物质子膜、非氟离子复合膜和酸碱聚合物复合膜的制备、结构和性能.并分析了它们各自的优点和存在的问题,对未来质子交换膜的发展作出了展望.