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一、前言聚电解质指含有聚离子的物质,其大分子上连接着大量可离子化的基团。与大多数无电荷的高聚物不同,聚电解质通常能溶解于极性溶剂(如水)。从其水溶液中质子化平衡的角度出发,聚电解质可分为聚多酸和聚多碱,若酸碱基团同时存在则称为聚两性电解质。聚电解质在溶液中的结构性质不同,可以将其分为线型、枝型和网状结构。高度交联的聚离子不溶解在水中,但可以显著溶胀。聚电解质又根据不同来源分为合成和天然两大类。合成的 相似文献
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聚电解质溶液的分子热力学模型姜建文刘洪来胡英(华东理工大学化学系上海200237)自然界、生物体中的许多物质,诸如核酸、蛋白质等均为聚电解质溶液。聚电解质溶液具有高分子溶液的特性,同时由于其中的聚离子带有相当强的电荷,这使得聚电解质溶液的许多性质都与... 相似文献
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带相反电荷的聚电解质与表面活性剂之间具有强烈的相互作用,且通常伴随着相分离现象,从而产生了更多新用途,包括获得表面涂层、压缩/分离聚电解质和制备纳米材料等.介绍了多糖高分子类聚电解质与带相反电荷的表面活性剂间的相互作用. 相似文献
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考察了离子强度、反离子种类、溶剂性质及温度等对聚电解质和带相反电荷的表面活性剂胶束相互作用临界点的影响。结果表明,该类相互作用对以上影响因素敏感。其原因是此类相互作用主要受静电力控制,而静电力的大小取决于聚电解质的线性电荷密度及胶束表面电荷密度,这后二者对所考察的因素敏感。 相似文献
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将聚碳酸亚乙酯(PEC)与有机蒙脱土(OMMT)在超临界CO2(sc-CO2)中溶胀并混合,制备了生物可降解PEC/OMMT纳米复合材料。采用X射线衍射仪、热失重分析仪、差示扫描量热仪及万能电子拉力机等对PEC/OM-MT纳米复合材料的性能进行表征和分析。结果表明,70℃下制备的PEC/OMMT复合材料为插层型纳米复合材料;该复合材料的热稳定性和玻璃化转变温度都得到较大改善;加入少量OMMT,复合材料的拉伸性能得到明显提高。与熔融插层法和溶液插层法相比,sc-CO2法既可以解决PEC在熔融插层中面临的热降解问题,也可以避免溶液插层中使用大量有机溶剂造成的污染问题,是制备PEC/OMMT纳米复合材料的一种新方法。 相似文献
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利用双功能基偶联剂3-(2-吡啶联巯基)丙酸N-羟基琥珀酰亚胺酯(SPDP)合成了两个藻胆蛋白复合物,藻红蓝蛋白-变藻蓝蛋白复合物PEC-APC和藻红蓝蛋白-藻蓝蛋白复合物PEC-PC.利用吸收光谱和荧光光谱证明了藻胆蛋白构型与构象在反应后得到保持.通过荧光光谱观察到能量传递现象.计算出复合物PEC-APC的分子内能量传递效率约为90%.复合物PEC-PC中藻红蓝蛋白PEC的荧光寿命比PEC本身的寿命大大缩短,证明存在分子内能量传递.二硫苏糖醇(DTT)还原二硫桥键后能量传递被阻断.这进一步证明复合物合成成功及分子内能量传递. 相似文献
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壳聚糖/果胶聚电解质配合物的制备及其性能研究 总被引:6,自引:0,他引:6
用天然多糖壳聚糖和果胶合成壳聚糖 /果胶聚电解质配合物 ( PEC) ,探讨了 PEC合成过程反应机理 ,考察 PEC薄膜在水溶液中的溶胀行为、对 p H刺激响应性和做药物释放载体的可能性。关键词 :壳聚糖 ;果胶 ;聚电解质配合物用天然多糖壳聚糖和果胶合成壳聚糖 /果胶聚电解质配合物 ( PEC) ,探讨了 PEC合成过程反应机理 ,考察 PEC薄膜在水溶液中的溶胀行为、对 p H刺激响应性和做药物释放载体的可能性 相似文献
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ABSTRACT: The photoelectrochemical (PEC) responses of electron-irradiated 66-phenyl-C61-butyric acid methyl ester (PCBM)/TiO2 electrodes were evaluated in a PEC cell. By coating PCBM on TiO2 nanoparticle film, the light absorption of PCBM/TiO2 electrode has expanded to the visible light region and improved the PEC responses compared to bare TiO2 electrode. The PEC responses were further improved by irradiating an electron beam on PCBM/TiO2 electrodes. Compared to non-irradiated PCBM/TiO2 electrodes, electron irradiation increased the photocurrent density and the open-circuit potential of PEC cells by approximately 90% and approximately 36%, respectively at an optimum electron irradiation condition. The PEC responses are carefully evaluated correlating with the optical and electronic properties of electron-irradiated PCBM/TiO2 electrodes. 相似文献
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提出H型钢部分外包混凝土柱(PEC柱)结构,通过对18根PEC柱试件的轴心和偏心受压试验,研究了不同的碳纤维布粘贴层数、不同的碳纤维布粘贴间距、不同的偏心距分别对PEC柱的承载能力和破坏模式的影响。研究发现:粘贴碳纤维布的PEC柱承载力大于不粘贴碳纤维布的PEC柱;相同碳纤维布粘贴间距时,粘贴两层布比单层布的PEC柱承载力有所提高;碳纤维布粘贴间距越小,PEC柱的极限承载力越大;所有试件柱的极限承载力随偏心距的增大而降低。基于试验数据,提出承载力计算公式。 相似文献
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Polyelectrolyte complex (PEC) hydrogels composed of chitosan as a cationic polyelectrolyte and poly (γ‐glutamic acid) (γ‐PGA) as an anionic polyelectrolyte were prepared from PEC dispersions based on a chitosan solution to which different amounts of γ‐PGA solutions were added to charge equivalency. The chemical structures of the PEC hydrogels were investigated by Fourier transform infrared spectroscopy. The physical properties, fixed charge concentration, crystallinity, mechanical properties, micromorphology, and swelling properties of the PEC hydrogels were also investigated. The total fixed charge concentration of the PEC hydrogels varied as a function of pH on the pK intervals between chitosan (pK = 6.5) and γ‐PGA (pK = 2.27). The isoelectric points (IEP) were shifted to a lower pH with a higher weight ratio of γ‐PGA to chitosan. The elastic modulus was decreased with the weight ratio increasing from 0 : 1 to 1 : 1 (γ‐PGA/chitosan) by ionic crosslinking between the amino groups of chitosan and the carboxyl groups of γ‐PGA. The results of the swelling study showed that the swelling properties of PEC hydrogels were more affected by the change in the elastic restoring force than by the change in the fixed charge concentration depending on the pH. Also, the cytotoxicity of the PEC hydrogels was investigated using normal human dermal fibroblast (NHDF) cell lines, and the results showed the PEC hydrogels were not toxic. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:386–394, 2007 相似文献
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Pimchaya Luangaramvej Peeranuch Poungsripong Stephan Thierry Dubas 《Polymer International》2022,71(1):139-145
Polyelectrolyte complex (PEC) membranes prepared from poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) were modified by crossflow polymerization of aniline (ANI). The PEC membranes were used as separators in a two-compartment setup where ANI monomer and ammonium persulfate (APS) oxidant diffused through the membranes to form polyaniline (PANI). APS and ANI having different distributions throughout the membranes, the reaction led to the asymmetric polymerization of PANI on one face of each PEC membrane thus producing Janus membranes. Due to the excess PANI content, the membrane displayed distinct asymmetric electrical conductivities on each face. Interestingly, very different ANI polymerizations were obtained when nonstoichiometric PEC membranes having different molar ratio of cationic and anionic polyelectrolytes (P+:P? represents PDADMAC:PSS) were used and transport of APS was fastest through the 2:1 PEC when compared to the 1:2 PEC. In all experiments, the polymerization was most intense on the ANI side of the membranes. Also, the influence of NaCl both during PEC fabrication and during polymerization was studied and found to have some effect on the solute permeability. Results showed that a higher content of PANI was formed on PEC membranes having excess P+ and with no NaCl added during PEC fabrication. Although X-ray diffraction confirmed the presence of PANI on both sides of each membrane, scanning electron microscopy images demonstrated that both sides of each membrane had different PANI content deposited. Electrical conductivity measurements using a four-point probe setup also showed that the PEC–PANI exhibits asymmetric electrical property on different sides. © 2021 Society of Industrial Chemistry. 相似文献
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Mixtures of methyl glycol chitosan and glycol chitosan were reacted with poly(vinyl sulfate) to form many different water-insoluble polyelectrolyte complexes (PEC) in aqueous solution at various hydrogen ion concentrations. It was revealed from elemental analyses, infrared (IR) spectroscopy, and solubilities of PEC that molecular structures of each PEC are dependent on [H+]. PEC membranes were made from casting solutions of all kinds of PEC, and transport phenomena through the membrane of PEC prepared in a pH 13.0 solution were investigated under various conditions. The transport ratio of Na+ and the electric potential difference between the left- and right-hand sides of the membrane were measured, and it is suggested that the driving force for active transport depends on the membrane potential, Donnan potential and diffusion potential. Moreover, permeability of K+ was higher than that of Na+ in selective transport. 相似文献
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脉冲电流热加工(pulse electric current heat treatment,PECHT)具有低温、快速的特点。研究了脉冲电流烧结过程中温度和脉冲比对Fe烧结体性能的影响,并与相同温度、压力和保温时间下辐射加热热压烧结的Fe烧结体进行了比较。结果表明:脉冲电流烧结在较低温度下样品就能获得更高的致密度。脉冲比(ON/OFF)对烧结有很大影响,说明脉冲电流加热促进了颗粒之间的原子扩散。同时,脉冲电流加热烧结和辐射加热烧结过程中Al2O3和Cu的收缩曲线也为脉冲电流加热条件下扩散加强提供了佐证。2种加热条件下接触线之间原子扩散的研究表明:脉冲电流加热促进了原子的扩散。 相似文献
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Two polar polymers with different dielectric constants, poly(vinylidene fluoride) (PVDF) and poly(ethylene oxide) (PEO), were each blended with a chlorine-terminated poly(ethylene ether) (PEC) and one of the two salts, LiBF4 and LiCF3CO2, to form PEC plasticized polymer electrolytes. The room-temperature ionic conductivity of the PEC plasticized polymer electrolytes reached a value as high as 10?4 S/cm. The room-temperature ionic conductivity of the PVDF-based polymer electrolytes displayed a stronger dependence on the PEC content than did the PEO-based polymer electrolytes. In PVDF/PEC/LiBF4 polymer electrolytes, the dynamic ionic conductivity was less dependent on temperature and more dependent on the PEC content than it was in PEO/PEC/LiBF4 polymer electrolytes. The highly plasticized PVDF-based polymer electrolyte film with a PEC content greater than CF4 (CF4 defined as the molar ratio of the repeat units of PEC to those of PVDF equal to 4) was self-supported and nonsticky, while the corresponding PEO-based polymer electrolyte film was sticky. In these highly plasticized PVDF-based polymer electrolytes, the curves of the room-temperature ionic conductivity vs. the salt concentration were convex because the number of carrier ions and the chain rigidity both increased with increase of the salt content. The maximum ionic conductivity at 30°C was independent of the PEC content, but it depended on the anion species of the lithium salts in these highly plasticized polymer electrolytes. © 1995 John Wiley & Sons, Inc. 相似文献