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。     

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

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。     

SiO2/PVDF离子膜的选择透过性

高分子有机聚合物聚偏氟乙烯(PVDF)以其优良的物理化学性能而倍受青睐。但由于PVDF膜的疏水性,应用在水处理中时容易产生污染,使其应用受到了限制。制备了有机无机SiO2/PVDF离子膜。通过测试膜浓差电势,确定膜对离子的选择透过率和膜表面电荷密度。结果表明,添加纳米SiO2能提高PVDF膜对离子的选择透过率,但只有加入SiO2质量分数为0.21%时,离子膜的选择透过率和表面电荷密度才适宜。SiO2/PVDF-0.21离子膜电渗析对不同离子的去除效果试验表明,该电渗析对多组分离子溶液体系的离子总去除率达到了93.7%。     

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...     

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…

考察了聚电解质的线性电荷密度，分子量，非离子表面活性剂ＡＥＯｎ中ＥＯ数及离子表面活性剂中疏水基长度对题述相互作用的影响，结果表明，ξ有ＥＯ数的影响很大，而离子型表面活性剂中疏水基长度的影响不明显。     

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...     

粒子在溶液中吸附聚电解质行为及粒子间的相互作用(Ⅱ)数值分析和结果讨论

用Newdon -Raphson迭代法对链节密度分布模型进行数值分析 ,从理论上探讨了聚合物分子链在粒子表面的构象状况 ,聚合物分子量、分子链电荷密度、聚合物和溶剂的相互作用参数及聚合物和粒子表面相互作用参数等因素对分子链在粒子表面的吸附行为和吸附有聚合物的粒子间的相互作用的影响 ,并通过聚丙烯酰胺(PAM)和阳离子聚丙烯酰胺 (CPAM)在炭黑表面的吸附验证了所建立的模型     

聚电解质颜料分散剂

在高极性的水性介质中,颜料表面会带上电荷。这些表面电荷吸引了介质中的反离子而形成双电层,可以同性电荷相斥的库仑力来稳定其在介质中的分散。然而这些表面电荷密度不足以获得分散稳定化,更不足以满足水性涂料的要求(>20 mA)。当聚电解质以它的亲油基吸附在颜料表面上,就可以它离解基的电荷来提高表面电荷密度,并且它又可设计得与主成膜物有良好的混容性,所以在水性涂料中常采用之。     

聚电解质颜料分散剂

在高极性的水性介质中,颜料表面会带上电荷。这些表面电荷吸引了介质中的反离子而形成双电层,可以同性电荷相斥的库仑力来稳定其在介质中的分散。然而这些表面电荷密度不足以获得分散稳定化,更不足以满足水性涂料的要求(＞20mA)。当聚电解质以它的亲油基吸附在颜料表面上,就可以它离解基的电荷来提高表面电荷密度,     

Br?nsted酸强度对正碳离子转化方向影响的分子模拟

采用密度泛函理论(DFT)系统地研究了Br?nsted酸强度与催化反应过程中正碳离子转化活性之间的关系。通过调整B酸模型电子分布构建5种酸强度模型,其酸强度范围覆盖弱酸、强酸以及超强酸。将C4正碳离子作为模型化合物,计算其氢转移、异构化、脱氢、β断裂4种反应。计算结果表明氢转移的反应能垒与酸强度呈指数关系,其他3个反应能垒与酸强度呈线性关系。在弱酸范围内各反应对酸的敏感度由高到低排列如下:氢转移反应异构化反应β断裂反应脱氢反应,而在强酸范围内氢转移的酸敏感度最低。通过计算过渡态离子携带的电荷可知,反应活性对酸的敏感度与过渡态离子携带的Mulliken电荷有关。过渡态离子携带电荷越多,与酸性位的相互作用越强,所以提高酸强度时能更有效地降低反应能垒。该反应规律与实验结论相匹配,并且从原子层面解释了不同酸强度时实验产率变化的原因,对开发新型催化材料或者催化剂改性有重要意义。     

含盐聚电解质溶液的分子热力学模型

A molecular thermodynamic model of polyelectrolyte developed previously was extended to polyelectrolyte solutions with added salts.Thermodynamic properties,such as activity coefficients of polyelectrolytes or added salts and osmotic coefficients of solvent, of a number of aqueous mixtures of polyelectrolytes and salts are analyzed with the proposed model.Successful correlation is obtained in the range of moderate or higher polyion concentration.For the same sample,thermodynamic properties of polyelectrolytes with and without simple electrolytes can be predicted mutually using parameters from regression data.     

Studies on carboxymethyl cellulose. Viscosity dependence on polymer concentration and electrolyte content

Viscosity behaviour of sodium carboxymethyl cellulose (NaCMC) in water has been examined. The data obtained are treated with Fuoss, Liberti-Stivala, Jones-Dole-Fuoss, and Yuan et al., empirical as well as semiempirical relations to understand the polyelectrolytic character of NaCMC. The results obtained are compared with other polyelectrolytes. The effect of added salt, like sodium chloride, on the viscosity of NaCMC solution also has been reported. Isoionic dillution experiments have been carried out to determine the degree of ionization of the polyelectrolyte, which reveals a little dependence of the degree of free counterions on the concentration of carboxymethyl cellulose (CMC) solutions. This leads to the conclusion that the polyion gets dilated because of the osmotic effect caused on diluting the polyelectrolyte solution. Furthermore, it has been found that the theory of Oosawa accounting the additivity rule adequately explains the viscosity behaviour of CMC in simple salt solutions.     

NaCl在聚电解质溶液中活度系数的实验测定

引　言聚电解质是指在极性溶剂中能够电离形成聚离子和反离子的高分子[1] ,在生物体中广泛存在 ,如蛋白质、ＤＮＡ和ＲＮＡ等都是聚电解质 ,聚丙烯酸盐和聚苯乙烯磺酸盐则是典型的人工合成聚电解质 .在聚电解质的水溶液中 ,由于聚离子带有大量的电荷 ,对反离子具有很强的静电吸引作用 ,即使在极低的浓度下溶液仍具有很大的非理想性 ,这与普通电解质溶液显著不同[2 ,3 ] .建立聚电解质溶液热力学性质的计算方法一直是溶液理论研究的热点 ,现已取得长足进展 ,如Ｍａｎｎｉｎｇ的反离子凝聚理论[2 ,3 ] 、柱状胞腔模型基础上的ＰＢ方程理论[4 ,…     

The physical chemistry of polyelectrolyte solutions

Some physical properties of aqueous solutions containing linear, flexible, polyelectrolytes are reviewed in order to emphasize the role of charge interactions in these systems which strongly depend on the charge of the macromolecular chain and the concentration of low molar mass electrolyte in solution. Particular emphasis is put on polyelectrolyte solutions containing an excess of added salt, which from a theoretical point of view are easier to understand. Both the dilute and the semi-dilute case will be discussed. In the former the problem of the electrostatic potential around the macromolecular chain is briefly reviewed as well as the use of a wormlike chain model to derive average dimensions of polyelectrolytes in solutions. In the latter the scaling approach to concentration effects in polyelectrolyte solutions is briefly discussed. The pecularities of the semi-dilute regime in polyelectrolyte solutions is illustrated with the help of results obtained with dynamic light scattering and the time dependent decay of electric birefringence.     

Electro-optical and viscometric behaviour of sodium polystyrene sulphonate in formamide

Unusual electro-optical signals have been recorded on sodium polystyrene sulphonate in formamide. It was shown that such signals largely arise from the positive birefringence of the solvent being superimposed on the negative birefringence of the polyion. On the basis of conductimetric experiments, the residual content of ammonium formate caused by hydrolysis of formamide was estimated. Commercial formamide of analytical grade was shown to contain rather large amounts (0.02 M) of ammonium formate, sufficient to very strongly decrease the polyelectrolyte effect. The persistence length in these conditions is equal to 80Å, quite similar to that determined in 2 × 10^?2 M NcCl aqueous solution. At a lower ammonium formate content (7 × 10^?4 M), the degree of extension of the polyion at infinite dilution, calculated from the relaxation time of the birefringence, is identical to that measured in 6 × 10^?4 M NaCl. The influence of the nature of the solvent and the ionic strength on the electric polarizability and the optical anisotropy factor was also analysed and compared with the results obtained in water. The latter parameter was discussed in terms of the so-called form anisotropy of the solvent and the intrinsic optical anisotropy of the polyion.     

Counterion association to cationic polyelectrolytes in methanol/water mixtures

The effect of the nature of the medium on the chloride and bromide condensation to a cationic polyelectrolyte was studied. Methanol/water mixtures were used as solvent in order to vary continuously the properties of the medium. The counterion–polyion interaction was studied by the determination of the Eisenberg interaction parameter (f^*) by means of electrical conductivity measurements. Results indicate that f^* parameters increase while the limiting electrical conductivity is rapidly decreasing. This apparently anomalous phenomenon is interpreted as a preferential solvation of the polyelectrolyte which brings about a conformational change, as revealed by the intrinsic viscosity behavior of the solutions. This change could induce an increase in the average distance between charges without further dissociation, which could explain the observed behavior of the f^* parameter. It is concluded that the actual dielectric constant which governs the polyion–counterion interaction in the polyelectrolyte domain is not the bulk dielectric constant.     

The influence of electrospinning parameters on the structural morphology and diameter of electrospun nanofibers

Electrospinning is a simple method of producing nanofibers by introducing electric field into the polymer solutions. We report an experimental investigation on the influence of processing parameters and solution properties on the structural morphology and average fiber diameter of electrospun poly ethylene oxide (PEO) polymer solution. Experimental trials have been conducted to investigate the effect of solution parameters, such as concentration, molecular weight, addition of polyelectrolyte in PEO solution, solvent effect, as well as governing parameter, such as applied voltage. The concentration of the aqueous PEO solution has shown noteworthy influence on the fiber diameter and structural morphology of electrospun nanofibers. At lower concentrations of PEO polymer solution, the fibers showed irregular morphology with large variations in fiber diameter, whereas at higher concentrations, the nanofibers with regular morphology and on average uniform fiber diameter were obtained. We find that the addition of polyelectrolytes, such as sodium salt of Poly acrylic acid (PAA) and Poly allylamine hydrochloride (PAH), increases the conductivity of PEO solutions and thereby decreases the bead formation in electrospun nanofibers. The increase in applied voltage has been found to affect the structural morphology of nanofiber while the addition of ethanol in PEO solution diminishes the bead defects. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Open circuit voltage for solid polymer electrolyte/salt systems in lithium batteries

The open circuit voltage (OCV) model of the solid polymer electrolyte (SPE)/salt system in lithium batteries is established by combining concentrated solution theory with the modified double lattice–non-random (MDL-NR) model which describes the non-ideal behavior of the salt activity in the polymer electrolyte. The activity parameters are obtained from the phase diagram for the given systems and used to describe the OCV of the corresponding systems with one additional parameter, transport number, t ₊ ⁰ . The proposed model agrees very well with the OCV data for various PEO/salt systems.     

Quantitative analysis on swelling behavior of HSMA/PVA IPN ionic gels under electric field

In order to explain the electric response of HSMA/PVA IPN ionic gel, polyion concentration (0 and/or interaction parameter (x_ij) between gel and water are used, which were previouslydetermined elsewhere by comparing swelling behaviours in the mixed solvents with Tanaka’s theory [1], Ionic polymer gel separated from the electrodes exhibits exponential responses when the electric field is applied or stopped, where the characteristic times for swelling and shrinking and equilibrium swelling ratio are successfully correlated with polyion concentration or interaction parameter. In addition, the strength of field is also an important factor to determine the overall responses. The direction of gel with respect to the electric field is also considered and optimum size was apparent to show maximum swelling.