PAN/PMMA凝胶聚合物电解质膜导电动力学分析

采用静电纺丝法制备PAN/PMMA(聚丙烯腈/聚甲基丙烯酸甲酯)凝胶聚合物电解质膜,用交流阻抗法测试其在不同温度下的电导率,研究温度对凝胶聚合物电解质膜离子传输性能的影响规律;并与溶液浇铸法制得的平滑膜进行对比,分析两种不同形式凝胶聚合物电解质膜的导电动力学规律,探索其导电机理与微观形貌的关系.结果发现,两种薄膜的导电机理符合Arrhenius公式,其中纺丝薄膜的离子导电活化能较低.     

基于新型交联聚合物电解质的准固态染料敏化太阳能电池

采用柠檬酸(CA)交联聚乙二醇(oligo-PEG, 平均分子量M_w=200, 400, 1000, 2000), 合成具有可生物降解性能的聚柠檬酸-乙二醇(PCE)交联聚酯, 并以此为基体材料制备得到准固态的三维交联型PCE/LiI/I₂聚合物电解质. 采用红外吸收光谱(IR)、核磁共振氢谱(¹H-NMR)、扫描电镜(SEM)和Raman光谱分别对PCE基体的分子结构、聚合物电解质的微观形貌以及导电离子对的存在形式进行表征; 通过线性扫描伏安法(LSV)研究了聚合物电解质的离子扩散系数、电导率以及电池的输出电流-电压(I-V)性能. 结果表明, PEG的分子量影响PCE基体膜的微观形貌及其吸液性能, 从而影响聚合物电解质的离子导电性能及电池的光电性能: 随着PEG分子量M_w从200, 400, 1000增大到2000, PCE基体膜的结构变得疏松, 吸液率增加, 吸液溶胀后的基体中I-3的跃迁活化能降低, 导致电解质的电导率和电池的短路光电流密度随之增加; 在60 mW·cm^-2的入射光强下, 四种电解质对应电池的光电转化效率依次为3.26%、3.34%、4.26%和4.89%.     

离子液体基聚合物的结构对染料敏化太阳能电池性能的影响研究

设计合成了分别悬挂磺酸官能团、磺酸锂官能团和烷基链官能团的三种结构的离子液体基聚合物,用于聚合物凝胶电解质的制备,并应用于染料敏化太阳能电池中.结果发现这三种聚合物含量的变化对电池性能的影响有较大差别.悬挂普通烷基链官能团的离子液体基聚合物(P-CH₃I)的加入,由于增加了电解质的粘度,使得电池的性能随着P-CH₃I含量的增加而变差;悬挂磺酸锂官能团的离子液体基聚合物P-LiI加入使电池的性能略微下降,而悬挂磺酸官能团的离子液体基聚合物P-HI加入到离子液体电解质后,在一定浓度范围内能改善离子的扩散等性能,从而使基于这种离子液体基聚合物的电池的光电性能相对较好.并通过电解质AFM微观形貌的研究解释了这三类电解质中离子扩散的差异以及光电性能的差别.     

燃料电池用聚乙烯醇基碱性聚合物电解质膜的制备及其性能

通过在不同浓度KOH溶液中进行掺杂,制备出了聚乙烯醇(PVA)、聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)和聚乙烯醇/聚乙二醇二甲醚(PVA/PEGDE)碱性聚合物电解质膜详细考察了膜的外观形貌、微观结构、热稳定性、离子电导率和化学稳定性等.结果表明,PVA与PVP以及PEGDE具有很好的相容性,所制备的复合膜断面致密...     

聚合物防污材料表面水化层的分子动力学模拟

采用分子动力学方法研究了吸附在聚二甲基硅氧烷(PDMS)和接枝聚磺酸基甜菜碱甲基丙烯酸甲酯(pSBMA)改性后的防污材料膜水化层内的水分子的结构及其动力学性质, 从微观角度解释了聚合物膜具有防污性能的原因. 模拟发现: (1)紧靠聚合物膜形成的水化层是聚合物具有防污性能的关键因素, 该水化层是溶液中的粒子(包括蛋白质分子)与聚合物膜相接触时所要克服的最主要的物理能障; (2)相对PDMS聚合物膜而言, 双离子特性自组装膜(pSBMA)在氢键、静电力的共同作用下, 可以形成空间笼状水分子网结构对水分子具有更强的束缚作用并有效降低水分子的可运动性, 形成的稳定水化层使得pSBMA具有更强的阻碍蛋白质吸附的能力.     

锂离子电池PMMA-VAc聚合物电解质的制备与性质研究

以甲基丙烯酸甲酯(MMA)和醋酸乙烯酯(VAc)为单体, 用乳液聚合法合成聚甲基丙烯酸甲酯-醋酸乙烯酯聚合物(PMMA-VAc), 并以此聚合物制备了新型聚烯烃膜支撑的聚合物膜及聚合物电解质. 用红外光谱(FTIR)、凝胶色谱(GPC)、差热和热重分析(DSC/TG)、扫描电镜(SEM)及电池充放电实验等方法研究了聚合物、聚合物膜和聚合物电解质的性质. 红外光谱结果表明, MMA与VAc通过各自的C＝C双键打开聚合成PMMA-VAc. PMMA-VAc易于分散在混合碳酸酯溶剂中并形成凝胶, 凝胶粘度随PMMA-VAc浓度的增加而增加, 当浓度为4%时成膜效果最佳. PMMA-VAc膜具有大量的微孔结构, 具有极强的吸液性能. PMMA-VAc膜具有良好的热稳定性: 在380 ℃范围内保持稳定. 聚烯烃膜支撑的PMMA-VAc膜室温下的离子电导率为1.85×10^－3 S•cm^－1, 用作为锂离子电池的聚合物电解质时, 电池具有良好的循环稳定性和倍率性能.     

用于锂离子电池聚合物电解质的组成、结构和性能

聚合物电解质是全固态锂离子电池的重要组成部分, 其电导率对电池的性能有很重要的影响.本文综述了聚合物电解质的组成、结构和性能对锂 离子电池导电率影响的最新研究进展,特别是介绍了聚合物-碱金属盐复合电解质和聚离子体电解质两个体系的研究进展.     

一种新型凝胶态聚合物电解质的制备和性能

采用一种新型胶联剂新戊二醇二丙烯酸酯(noepentyl glycol diacrylate, NPGDA)和聚偏氟乙烯-六氟丙烯(poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP), 液态电解液组成电解质混合溶液, 然后加入引发剂并加热引发聚合反应制备了一种具有互穿聚合物网络结构的凝胶态聚合物电解质, 可以用于制备聚合物锂离子二次电池. 考察了不同PVDF-HFP/NPGDA质量比对凝胶态聚合物电解质性能的影响. 结果表明, PVDF-HFP/NPGDA质量比可以影响凝胶态聚合物电解质的结构形貌、电化学特性以及聚合物锂离子二次电池的性能. 研究发现, 当m(PVDF-HFP)/m(NPGDA)＝1:1时制备的凝胶态聚合物电解质具有较高的离子电导率和电化学稳定窗口, 室温下分别为6.99×10^-3 S•cm^-1和4.8 V(vs Li⁺/Li), 以其为电解质制备的聚合物锂离子二次电池具有较好的电化学性能.     

“Water-in-salt”聚合物电解质制备及其电化学性能研究

为提高柔性锂离子电池安全性和循环稳定性能,本实验以自由基聚合结合冷冻干燥得到的聚丙烯酰胺膜为电解质载体,引入21 mol·kg^-1 LiTFSI 高浓度电解液,得到“water-in-salt”聚合物电解质。通过聚合物膜的形貌和孔道结构表征,红外光谱分析,离子电导率及电化学稳定窗口测试等对其基本物化特性进行了研究。冷冻干燥得到的聚丙烯酰胺膜内部具有大量微孔结构,有利于电解液的载入。将该吸附了电解液的聚合物电解质膜与锰酸锂(LiMn₂O₄)正极和磷酸钛锂(LiTi₂(PO₄)₃)负极组装全电池进行充放电性能测试。结果表明,制得的柔性聚合物电解质具有良好的拉伸性能,高离子电导率(20°C,4.34 mS·cm^-1)和宽电化学稳定窗口(3.12 V)。以“water-in-salt”聚合物电解质为隔膜组装的LiMn₂O₄||LiTi₂(PO₄)₃ 全电池表现出优异的倍率性能和长循环稳定性。     

POSS星型聚合物对PMMA复合凝胶聚合物电解质性能的影响

为了提高凝胶聚合物电解质(GPE)的离子传输性,以低聚倍半硅氧烷(POSS)为核,臂结构为聚甲基丙烯酸甲酯(PMMA),臂聚合度不同的八臂星型聚合物(POSS-(PMMA3)8、POSS-(PMMA6)8、POSS-(PMMA9)8)为改性剂,分别与PMMA共混制备复合GPE,研究了POSS星型聚合物臂结构对复合GPE电性能影响的规律.结果表明,POSS星型聚合物的引入,使得复合GPE的电导率较纯PMMA基GPE均有显著提高,其中臂聚合度较小的POSS-(PMMA3)8复合GPE在室温的电导率最大,比纯PMMA基GPE提高了3.5倍.分析了该星型聚合物不同含量以及锂盐浓度等对复合凝胶聚合物电解质的影响,发现锂盐浓度在凝胶体系中为0.6 mol/L,该星型聚合物含量为聚合物基体15 wt%时,复合凝胶聚合物电解质电导率最大为2.73×10-4S/cm.研究了温度对复合凝胶聚合物电解质离子传输性能的影响规律,发现其离子传输规律符合Arrhenius方程.在此基础上,提出了该凝胶电解质体系的离子传输微观结构模型.     

Some Recent Advances in Pure and Applied Aspects of Graft Copolymers

In recent years more attention has been given to the preparation and characterization of graft copolymers and an examination of their properties than to developing novel methods of synthesis. In particular, these property studies can be used to develop applications of graft copolymers. The methods used to prepare and characterize better defined grafts are briefly reviewed. The structure of most graft copolymers is such that considerable amounts of one polymer can be grafted to another without affecting greatly the main properties of that polymer. In this way, the properties of one polymer such as higher water absorption can be imparted to another without changing the mechanical properties, for example, of the second polymer.

Some other inherent properties of graft copolymers are discussed, including their compatibility with the parent homopolymers, their possible con-formational changes, and other features. Finally, the use of the special nature of graft copolymers for the modification of the barrier properties of film and membranes is discussed as one possible general field of application.     

Thermosensitive Polymer Nanocontainers Prepared by Self-Assembly of Block Copolymers

In recent years, considerable effort has been devoted to the preparation of polymer nanocontainers because of their unique advantages. Compared to polymer microspheres or micelles,polymer nanocontainers are hollow-sphere structures and can encapsulate large quantities of guest molecules or large-sized guests within the "empty" core domain. Compared to polymer vesicles,polymer nanocontainers have enough mechanical stability to prevent them from structure changes due to covalent or ionic interactions responsible for their formation. Therefore, polymer nanocontainers have many potential applications such as confined reaction vesicles, drug carriers,protective shells for cells or enzymes, artificial cells and so on. However, most of polymer nanocontainers reported by now, load and release guest molecules from their interior only through diffuse mechanism. It is rather difficult to control intelligently the process based on demands. In order to solve this problem, one promising strategy is to design intelligent polymer nanocontainers.They can undergo reversible structural transitions from a closed to an open state with the help of external stimuli.In this paper, we report on our preliminary study of the thermosensitive polymer nanocontainers formed by self-assembly of the block copolymers PCEMA-b-PNIPAM and sequent photo-crosslinking of PCEMA shells.Block copolymers PCEMA-b-PNIPAM were prepared by reacting PHEMA-b-PNIPAM with excess cinnamoyl chloride in pyridine at room temperature, where PHEMA-b-PNIPAM was prepared by reacting succinimidyl ester of PHEMA-COOH with PNIPAAm-NH2, similar to the method of the literature. The block copolymers were characterized by FTIR and 1H-NMR and GPC.To obtain polymer vesicles, deionized water, as a precipitant, was added at a rate of 0.3wt%/10s with vigorous stirring to the PCEMA-b-PNIPAM solution in THE After the formation of polymer vesicles, more water was added until the water content reached ca.50wt%. The hollow structure of the polymer vesicles was clearly observed by TEM. Polymer nanocontainers with diameter range from tens of nanometers to thousands of nanometers can be obtained by changing formation condition. In order to obtain polymer nanocontainers with enough mechanical stability, the above polymer vesicles were crosslinked using UV light with a wavelength of 254 nm. The conversion of CEMA with irradiation time was monitored by measuring the decrease in absorbance at 274 nm,where converted PCEMA does not absorb. The CEMA conversion can be controlled from 0% to 50% by prolonging irradiation time. TEM images confirm that the morphology of the polymer nanocontainers is kept after irradiation.The thermosensitive property of the polymer nanocontainers in water was investigated using a Vis-UV spectrophotometer. The phase transition of the polymer nanocontainers takes place at about 40℃, and the structural reversibility in heating and cooling circle can keep well at least three times.     

燃料电池聚合物电解质膜

本文简要介绍了聚电解质膜燃料电池的定义、分类、工作原理及其特点,综述了国内外在燃料电池聚电解质领域的最新成果。对质子传导率与甲醇渗透系数的关系进行了初步探讨,详细评述了近年来AAPEM和ACPEM这两类聚电解质膜的研究进展,并对今后的研究趋势作了展望。     

Specifics of solvation of sulfonated polyelectrolytes in water, dimethylmethylphosphonate, and their mixture: a molecular simulation study

Sulfonated polyelectrolyte membranes (PEMs), such as Nafion and styrene-olefin block copolymers, are explored as permselective membranes for fuel cells as well as suitable barrier materials against chemical agents. The permselective properties of PEM are determined by their microphase segregation into hydrophilic and hydrophobic domains. We performed classical molecular dynamics simulations of solvation of the hydrophilic fragments of PEM exemplified on sulfonated polystyrene (sPS) with potassium, calcium, and aluminum as counterions, in water, phosphor-organic nerve agent simulant dimethylmethylphosphonate (DMMP), and their binary mixture. The force field for the sulfonate group has been developed by optimizing the potential parameters to fit the benzenesulfonate conformations obtained from the density functional theory. For a comparison, we considered perfluorosulfonate oligomers representing fragments of Nafion polymer. We found a noticeable difference between the geometries of the polymer backbone in different solvents. The polymer backbone is stiffer in DMMP for both sPS and Nafion. An anisotropic structuring of the solvent around the phenylsulfonate group is substantially stronger than around the Nafion sidechain due to the rigidity and the anisotropy of the phenylsulfonate group. The counterion significantly affects the conformations of solvated sPS: the rigidity of the backbone increases when potassium or calcium ions are replaced by trivalent aluminum ions.     

甲壳型液晶高分子研究进展与展望

简要介绍了甲壳型液晶高分子的模型理论, 概述了当前国内外对甲壳型液晶高分子设计、 液晶相态、 性质及基于甲壳型液晶高分子的嵌段共聚物体系的设计和自组装性质等研究进展, 展望了今后的研究方向.     

Nanometer‐Scale Water‐ and Proton‐Diffusion Heterogeneities across Water Channels in Polymer Electrolyte Membranes

Nafion, the most widely used polymer for electrolyte membranes (PEMs) in fuel cells, consists of a fluorocarbon backbone and acidic groups that, upon hydration, swell to form percolated channels through which water and ions diffuse. Although the effects of the channel structures and the acidic groups on water/ion transport have been studied before, the surface chemistry or the spatially heterogeneous diffusivity across water channels has never been shown to directly influence water/ion transport. By the use of molecular spin probes that are selectively partitioned into heterogeneous regions of the PEM and Overhauser dynamic nuclear polarization relaxometry, this study reveals that both water and proton diffusivity are significantly faster near the fluorocarbon and the acidic groups lining the water channels than within the water channels. The concept that surface chemistry at the (sub)nanometer scale dictates water and proton diffusivity invokes a new design principle for PEMs.     

Isomeric effect of sulfonated poly(arylene ether)s comprising dihydroxynaphthalene on properties for polymer electrolyte membranes

Polymer electrolyte membranes (PEMs) made of sulfonated poly(arylene ether)s consisted of 3,3′‐disulfo‐4,4′‐dichlorodiphenylsulfone disodium salt, 2,6‐dichlorobenzonitrile, and one of three dihydroxynaphthalene isomers (2,6‐, 2,7‐, and 1,5‐dihydroxynaphthalene, abbreviated as 2,6‐N, 2,7‐N, and 1,5‐N, respectively) were prepared with similar level of inherent viscosity and ion exchange capacity, and structural effect of the catenation in dihydroxynaphthalene isomers on membrane properties was compared. In the case of membranes for PEM fuel cell application with relatively high ion exchange capacity around 2.1 mequiv/g, three copolymers showed almost the same proton conductivity; however, swelling in water increased with the following order: 1,5‐N < 2,6‐N < 2,7N. In the case of direct methanol fuel cell membranes with lower ion exchange capacity around 1.5 mequiv/g, no remarkable difference in proton conductivity was also observed in three isomeric copolymers and swelling property and methanol permeability were lower in 1,5‐N and 2,6‐N copolymers than 2,7‐N copolymer. These tendencies show that higher rigidity or energy barrier for conformational change of polymer chain gives better performance of PEM for fuel cells with superior dimensional stability. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

后磺化法精确可控合成主链型磺化聚苯喹喔啉及其质子交换膜性能研究

以不同摩尔比的4,4′-双(4-(2-苯基乙二酮基)苯氧基联苯、4,4′-双(2-苯基乙二酮基)二苯醚与3,3′,4,4′-四氨基联苯共聚制备聚喹喔啉,经后磺化法得到一系列磺化度可控的磺化聚苯基喹喔啉(SPPQ).模型化合物确认,磺酸基团精确接入电子云密度较高的含醚键的联苯片段的2,2′-位上,证明通过单体分子结构设计与后磺化法结合,可使磺酸基团在温和条件下,按预想接入到聚合物主链上,达到磺化度和磺化位置精确可控的目的. SPPQ的相对黏度均在3.8 dL/g以上.通过溶液涂膜法制备的主链型磺化聚苯基喹喔啉质子交换膜(SPPQ PEM)的吸水率都低于39%,尺寸变化率为2.1%~13%,且随着IEC和温度的提高而线性增加.如,80℃下,IEC高达2.21 meq/g的SPPQ-5的膜面和膜厚方向的尺寸变化率仅为11%和13%,具有良好的形状维持能力.热重分析表明,SPPQ PEM在320℃左右脱去磺酸基团,550℃左右发生聚合物主链降解,具有良好的热稳定性. Fenton试剂测试表明,SPPQ PEM开始破碎的时间随IEC的增加而缩短,在20℃时,IEC较低的SPPQ-1 (1.29 meq/g)破碎时间可达151 h,而IEC较高的SPPQ-5(2.21 meq/g)破碎时间缩短至81 h. PEM的质子传导率随温度和IEC的增加而显著提高,最高可达64 mS/cm,由于磺酸基团和喹喔啉酸碱对的形成以及吸水率偏低的原因,这一数值远低于Nafion.     

Multilayers of weak polyelectrolytes of low and high molecular mass assembled on polypropylene and self-assembled hydrophobic surfaces

Hydrophobic self-assembled octadecyltrichlorosilane (ODTS), ultrathin films of polypropylene, and ODTS modified with cationic dioctadecyldimethylammonium bromide are employed as substrates for deposition of multilayers of poly(allylamine hydrochloride) and poly(acrylic acid) from aqueous solution. The assembly of highly dissipative polyelectrolyte multilayers (PEMs) is demonstrated by quartz crystal microgravimetry. The initial rate of adsorption is faster and the adsorbed amount larger on the cationic surface, while the detailed structure of the PEMs, as determined by atomic force microscopy imaging, is related primarily to the molecular weight of the adsorbing polymers. A more extensive PEM adsorption on the hydrophobic surfaces takes place with increasing ionic strength of the background electrolyte solution. The water contact angle depends on the type of polymer adsorbed as the outermost layer, indicating that, despite the expected interdiffusion for the different polymer chains, there is a net macromolecular segregation to the free surface. Surface modification with the high molecular weight PEMs produces a more marked reduction of the hydrophilicity of the substrate.     

Polymer electrolyte membranes for the direct methanol fuel cell: A review

The direct methanol fuel cell (DMFC) has the potential to replace lithium‐ion rechargeable batteries in portable electronic devices, but currently experiences significant power density and efficiency losses due to high methanol crossover through polymer electrolyte membranes (PEMs). Numerous publications document the synthesis and characterization of new PEMs for the DMFC. This article reviews this research, transport phenomena in PEMs, and experimental techniques used to evaluate new PEMs for the DMFC. Although many PEMs do not show significant improvements over Nafion®, the benchmark PEM in DMFCs, experimental results show that several new PEMs exhibit lower methanol crossover at similar proton conductivities and/or higher DMFC power densities. These results and recommendations for future research are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Parts B: Polym Phys 44: 2201–2225, 2006