聚电解质溶液的分子热力学模型

采用事电柔性硬球链近似链状聚离子,从微扰理论和离子缔合理论出发,建立了链状聚电解质溶液的分子热力学模型,并引入聚离子与反离子间的缔合以计及短程作用。成功地计算了聚电解质溶液的热力学性质,所得结果与计算机模拟数据、实验结果吻合。     

聚电解质溶液分子热力学模型

<正>链状聚电解质由于是长链大分子又有很高的电荷密度,其溶液即使在极低的浓度下仍具有很强的负偏差,与Debye-Huckel理论预测的结果相去甚远。工程上使用的Manning模型认为聚离子的电荷密度有一临界值,当超过临界值时,反离子即凝聚在聚离子表面使其实际电荷密度降至临界值。Nagvekar等在该模型的基础上引入NRTL方程,以计及短程相互作用的贡献。Manning等的方法虽然有一定的物理意义,但临界值的确定缺乏可靠的根据。     

相反电荷聚电解质复合的模拟

基于刚性聚电解质复合物模型,推导了体系中各自由离子的浓度,提出包括复合与反离子凝聚竞争的平衡反应模型,模拟了相反电荷聚电解质在盐水介质中的复合与解离过程.结果表明,复合过程伴随着聚电解质双电层厚度的压缩；客主体聚电解质的电荷摩尔比为1时,复合达到饱和,与荧光各向异性比在X.为1时达平台的实验结果所反映的一致；离子强度增...     

用微扰理论状态方程计算电解质水溶液的活度系数

近年来,电解质溶液理论的研究日益活跃^[1]。因为理论模型能反映微观粒子参数与溶液结构和性质间的关系,参数物理意义明确,预测功能强。电解质溶液的原始模型中,忽略了离子－溶剂和溶剂－溶剂相互作用,而只考虑在溶剂平均场中离子之间的相互作用。这类模型不能反映溶液的本质和溶质－溶剂间的真实相互作用,因此很难推广到混合溶剂电解质溶液。用微扰理论研究电解质溶液的状态方程已经取得很大进展^[2]。硬球离子流体^[3]和离子－偶极^[4]模型流体的微扰理论处理结果已经成功地用于构筑实际电解质溶液的状态方程^[5]。作者采用微扰理论研究了电解质溶液的密度性质^[6],本文将进一步研究活度系数的计算问题。     

聚电解质的特性及应用

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     

AM/AMPS/DMC聚两性电解质的合成、表征与溶液性能

以丙烯酰胺(AM)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为原料,在0.5 mol/L NaC l溶液中,以2,2-偶氮二[2-(2-咪唑啉-2-代)丙烷]二氢氯化物(VA-044)为引发剂,合成了AM/AMPS/DMC系列聚两性电解质。利用13C NMR对共聚产物结构进行表征,结果表明,在高转化率情况下,共聚物组分与投料比基本一致。考察外加小分子电解质和温度对聚两性电解质溶液性能的影响,结果显示,阴、阳离子数量相近的聚两性电解质溶液的粘度随外加盐浓度增大而增大,在温度升高时,其表观粘度保留率高于聚丙烯酰胺,说明AM/AMPS/DMC系列聚两性电解质具有一定的抗温、耐盐能力。     

生物合成聚γ-谷氨酸(钠盐型)稀溶液的粘度特性

为了确定特定条件下生物合成聚γ 谷氨酸(γ PGA)稀溶液的Mark Houwink方程参数,从而在关系适用范围内能够通过比较简单的特征粘数测量对γ PGA的相对分子质量进行快捷而可靠的估算,用毛细管粘度计法对钠盐型γ PGA稀溶液的粘度特性进行了系统考察。结果发现钠盐型γ PGA是一种典型的聚电解质,在一定浓度范围内显示了比浓粘度独特的浓度依赖性:不服从Huggins方程。中等离子强度的外加小分子强电解质会减小γ PGA稀溶液的特性粘数[η],并使之呈现出正常的粘度行为,且[η]与溶液中离子强度的-1/2次幂成较好的线性关系。[η]具有一定的时间依赖性。     

聚电解质溶液的分子热力学模型

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...     

相反电荷聚电解质浓溶液复合体系的粘弹性

考察了相反电荷聚电解质浓溶液的复合体系形成宏观单相的可能性,发现只有当聚电解质所带电荷被完全屏蔽时才可能呈宏观单相体系.弱聚电解质NaPAA与PDADMAC复合体系当聚合物总浓度大于13.3wt%时即为均相溶液,具有与中性高分子稀溶液相似的流变行为.而强聚电解质ADPy/PDADMAC、NaPSS/PDADMAC复合体系为悬浮液.粘弹性测试表明NaPSS/PDADMAC体系中形成了由聚离子桥链连接复合物粒子构成的三维网络.     

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研究──Ⅰ介质性质的影响

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的表面电荷密度，这后二者对所考察的因素敏感。     

用ISE法快速测定混合电解质溶液的活度系数

对ＮａＣｌ－ＫＣｌ－Ｈ２Ｏ溶液利用离子选择性电极（ＩＳＥ）的连续滴加法，快速测定出响应ＮａＣｌ的电动势，获得与用文献报道的活度系数计算出的电动势相一致的结果。由此电动势出发可以关联得到混合电解质溶液活度系数的Ｐｉｔｚｅｒ方程的参数，计算ＫＣｌ的活度系数同陆小华－Ｍａｕｒｅｒ提出的电解质溶液模型的预测结果也完全一致，表明本文方法可用于混合电解质溶液活度系数的快速测定。     

相反电荷强聚电解质复合物盐溶液的粘度研究

合成了高电荷密度的磺酸基强聚电解质,考察了其与阳离子聚电解质聚二烯丙基二甲基氯化铵（PDADMAC）稀溶液复合体系的流动特性。无论外加盐浓度高低,剪切速率高于10s^-1时,复合体系都表现出牛顿流体的行为。在水溶液中,随PDADMAC的增加,复合体系的增比粘度逐渐减小;在高浓度的NaCl溶液中,随PDADMAC的增加,体系的增比粘度基本保持不变。随体系离子强度增大,复合体系增比粘度出现极大值,反映了复合聚集的加强;继续增大离子强度,则复合解离,增比粘度变小直至恒定。     

聚-4-偶氮磺酸基苯乙烯与四-（三甲氨基苯基）-卟啉的自组装膜及其光电转换性能

聚-4-重氮基苯乙烯（PDS）在碱性水溶液下通过与Na2SO3反应，制备了聚-4-偶氮磺酸基苯乙烯（PDSS）．作为负离子聚电解质PDSS能与四-（三甲氨基苯基）-卟啉（TTMAP）通过离子相互作用进行层-层自组装．光照下该组装膜中的离子键转变为共价键，结果是组装膜对极性溶剂和盐水溶液变为非常稳定，从而能直接在KCl水溶液中测定其光电流．结果表明，该组装膜具有良好的光电转换性质．     

Thermodynamic properties of hydrobromic acid in 5 wt% 1-butanol-water,and 5 wt% 2-methyl-1-propanol-water-mixture from emf measurements

From the electromotive force measurements of the cell Pt (or Pd), H₂(g)|HBr(m), 5 wt% alcohol-water mixture|AgBrAg for different m in the temperature range from 288.15 to 308.15 K, the standard potential of AgAgBr electrode has been determined in the mixture where alcohol was 1-butanol and 2-methyl-1-propanol. The standard thermodynamic quantities for cell reaction and for HBr formation, the activity coefficients of HBr, and the standard thermodynamic quantities for the transfer of HBr from water to mixed solvents have been evaluated. The transfer functions were compared with those for water mixtures of other isomeric butanols as well as for the mixture with small proportions of other alcohols.     

Ultra-fine polyelectrolyte fibers from electrospinning of poly(acrylic acid)

Ultra-fine polyelectrolyte fibers have been generated from electrospinning of poly(acrylic acid) in aqueous and DMF solutions. The fiber diameters ranged from 80 to 500 nm and increased with increasing solution concentrations and electrospinning voltages. The fibers generated from the aqueous solutions were more homogeneous in sizes, especially when NaCl or NaOH was added. Higher voltages in electrospinning of the aqueous solutions also resulted in fibers with larger heat capacity in the glass transition region, and higher dehydration temperatures. These polyelectrolyte fibers could be rendered water-insoluble by incorporating β-cyclodextrin (at 20 wt% of PAA) in the aqueous solution, then heat-induced crosslinking was performed at 140 °C for 20 min. The resulting hydrogel fibers showed strongly pH-responsive swelling behaviors.     

Dilute solution properties of anionic poly(potassium-2-sulfopropylmethacrylate)

The dilute solution properties of an anionic polyelectrolyte, poly(potassium-2-sulfopropylmethacrylate) [poly(SPM)], are studied by measurements of polymerization rate, intrinsic viscosity, degree of binding, ionic strength, and critical micelle concentration. The polymerization of SPM in 0.5M NaCl aqueous solution proceeded more easily than that of SPM in pure water. The polymerization rate of SPM is found to pass through an extreme value as a function of pH. The intrinsic viscosity of this polyelectrolyte is related to the type and concentration of the salt added. The intrinsic viscosity for anionic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is in contrast with the polyampholyte. The polyelectrolyte in a high concentration of NaCl has a low degree of binding, indicating that the proton ion (H⁺) is relatively difficult to bind to the sulfonate group (SO⁻₃) at the polymer end. An increase in ionic strength causes the pKa (dissociation constant) to decrease at the half-neutralization point. The monomer solutions exhibit a plot typical of those observed for detergents, with a break in the curve occurring at the critical micelle concentration. For the polymer solutions, no break in the equivalent conductance curve was found for the concentrations studied. The polymer is adapted for use as viscosity-controlling agents in secondary oil recovery operations by water flooding. We have the proposed models to account for the poly(SPM) solution viscometrics. © 1997 John Wiley & Sons, Inc.     

季铵化聚乙烯醇/聚二甲基二烯丙基氯化铵/正硅酸乙酯杂化阴离子交换膜的制备与性能表征

通过在季铵化聚乙烯醇(QPVA)和聚二甲基二烯丙基氯化铵(PDADMAC)混合聚合物水溶液中添加正硅酸乙酯(TEOS)进行溶胶-凝胶反应,制备得到了不同配比的溶胶-凝胶铸膜液,并将各铸膜液在模具中干燥得到杂化膜,随后将杂化膜在戊二醛/丙酮溶液中交联得到尺寸稳定的杂化阴离子交换膜。考察了季铵化聚乙烯醇和聚二甲基二烯丙基氯化铵铸膜液的质量比对杂化膜稳定性的影响。主要分析了4种尺寸稳定阴离子交换膜的外观形貌、红外光谱、微观形貌、热稳定性、含水/甲醇率和膜的离子交换容量。结果表明,QPVA/0.25PDADMAC/0.1TEOS碱性杂化膜在甲醇中尺寸稳定,微观结构致密,在65～140℃时热稳定性优良,离子交换容量可达到1.091 41 mmol/g。具有在中低温型碱性直接甲醇燃料电池中使用的潜力。     

包覆多层聚电解质/树状大分子的聚合物微球表面CdS纳米粒的形成

将聚酰胺-胺(PAMAM)树形大分子、聚对苯乙烯磺酸钠(PSS)和聚二烯丙基二甲基氯化铵(PDADMAC)在三聚氰胺甲醛(MF)微球上进行静电自组装,制得聚电解质壳层的核壳式微球. 通过反应沉积吸附方法生成具有稳定荧光性能的CdS/聚电解质核壳式复合微球. 用透射电镜表征复合微球形貌,用反射紫外和荧光表征了CdS/聚电解质核壳式复合微球的光学特性.     

Standard pH values for potassium hydrogenphthalate reference buffer solutions in acetonitrile—water mixtures up to 70 wt% at various temperatures

Reference value standards, pHs, for 0.05 mol kg⁻¹ potassium hydrogenphthalate (KHPh) reference buffer solutions in 30, 50 and 70 wt% acetonitrile—water mixed solvents at temperatures from 288.15 to 308.15 K have been determined from emf measurements of the reversible cell Pt|Ag|AgCl|KHPh + KCl|Quinhydrone|Pt, in which the H⁺-reversible quinhydrone electrode replaces the ill-behaving hydrogen electrode. Values of the first ionization constant of the o-phthalic acid (H₂Ph; benzene-1,2 dicarboxylic acid) in these mixed solvents have also been determined from analogous measurements. The consistency of the present results with the previously determined pHs values in 5, 15 and 30 wt% acetonitrile—water mixtures is analysed by multilinear regression of pHs as a function of both solution composition and temperature. These smoothed standard pHs values are used to optimize the parameters of an equation predicting pHs values in different aqueous organic solvents.