The Calculation of Surface Potential for Spherical Ionic Micelles

In this article, an approximate expression for the calculation of surface potential for spherical ionic micelles has been presented. This simple analytic form overcomes the complexity of original theory. The calculated values of surface potential of spherical ionic micelles are in quite good agreement with the exact numerical values of nonlinear Poisson‐Boltzmann equation.     

关于表面张力和表面自由能的讨论

简要地回顾了表面物理化学中表面张力和表面吉布斯自由能(以下简称为表面自由能)两个基本概念的发展历史,讨论了表面张力和表面自由能形成的机制,以及键能与表面张力的关系,最后指出了尽管表面相可以在理论上抽象为几何面,但它是真实存在的独立相,而且由于表面自由能的原因它始终处于亚稳定状态.     

Electrical Properties of Highly Charged Spherical Reverse Micelle

A simpler expression of the surface charge density/surface potential relationship for spherical reverse micelles is obtained. In order to illustrate its application the approximate solution was used to calculate the thermodynamic characteristics and adsorption excesses. The approximate solution is based on the extended Langmuir's approach to the Poisson‐Boltzmann equation. The solutions for spherical reverse micelle are quite accurate provided that their radius and surface charge density are relatively larger. It is anticipated that this solution will be much easier to use in applications.     

液滴在不互溶液体表面上的相对界面自由能曲面及Neumann三角形的导出

根据系统的界面Helmholtz自由能自发地趋于最低的热力学原理,以浮在不互溶液体(2)表面上透镜状液滴(3)在气(1)、液₂、液₃三相交界处,气-液₃、液₂-液₃界面各自和气-液₂界面通过液滴内部的夹角θ₁、θ₂为变量(0°≤θ₁≤180°,0°≤θ₂≤180°),证明出3个界面张力γ₁₂、γ₁₃、γ₂₃各种可能组合情况下液体₃稳定时的θ₁、θ₂值与它们之间的关系,导出Neumann三角形;并按照计算数据绘出几种类型相对于气相中圆球形液滴的界面自由能曲面图。     

Numerical Calculation of the Electrostatic Potential Around an Ionic Micelle with Counter Ion Binding

A numerical solution of the nonlinear Poisson-Boltzmann equation (PBE) is presented for a system of spherical micelles with counterfoil binding. The approach investigates the following effects on ion micelle interactions, (i) total surface charge, (ii) competitions of different counter ions on micellar surfaces and (iii) surface potential determination. The theory is applied to interpret the ion activities in micellar solution as measured by ion-selective electrodes.     

油/水界面张力的影响因素及无机盐对油水铺展的影响

讨论不同有机相与水形成的油/水界面处水/气、油/气及油/水3个界面张力的影响因素及相对大小。重点讨论了加入无机盐对作用于透镜状油滴上的3个界面张力的影响,总结出基本的规律并进行了实验验证。     

OCS表面活性剂在弱碱、无碱条件下的界面张力性能研究

研究了OCS表面活性剂中试产品在弱碱NaCO33及无碱条件下应用于不同油田原油的油-水界面张力特性。结果表明：对于大庆采油四厂原油，当表活剂浓度为0．1％-0．3％，Na2CO3浓度为0．6％-1．2％时，油-水界面张力可达到超低(-l0^-3mN／m数量级)；对于大庆采油二厂原油，当表面活性剂浓度为0．1％-0．3％，Na2CO3浓度为0．8％-1．4％时，油-水界面张力可达到超低；对于华北油田古-联原油，当表面活性剂浓度为0．2％，NaCO3浓度为0．6％-1．2％时，油-水界面张力可达到超低；对于胜利油田孤东采油厂原油，当表面活性剂浓度为0．2％，NaCO3浓度为0．8％-1．4％时，油-水界面张力可达到超低。在无碱条件下，对于大港油田枣园1256断块原油，当OCS表面活性剂浓度达到0．1％时，油-水界面张力即可达到超低；对于江苏油田原油，当OCS表面活性剂浓度在0．1％以上时，油-水界面张力均可以达到10^-2mN／m数量级。聚丙烯酰胺聚合物的加入对油-水超低界面张力的形成和稳定具有促进作用。     

硝酰胺二聚体静电能和交换能的理论计算

根据对称性匹配微扰理论, 并运用多个微扰和非微扰方法, 计算了硝酰胺二聚体在不同分子间距(R)时静电能和交换能. 这些具有轨道弛豫的静电能不仅含有第4级单、双、四和三重激发态项, 而且含有CCSD的第5级和更高级的能量项. 同时发现: 第4级的三重激发态能量项比第5级和更高级的能量项之和还重要. 求得的含有分子内电子相关效应的交换能达到了CCSD水平. 用于计算交换能关联校正项的单对交换近似在硝酰胺二聚体的范德华最小距离0.42 nm附近区域才较合理. 在R为0.32～1.42 nm范围, 静电能与R的关系有两种: 一是在小于等于0.47 nm时, (R^－7.64; 二是大于0.47 nm时, (R^－3.97. 交换能具有明显的短程作用特点, 其与R间的关系为指数衰减: 21.061exp(－R/0.318). 最后发现: 在硝酰胺二聚体中, 分子内的电子相关效应对和的影响很显著.     

固体的表面能及其亲水/疏水性

固体表面的亲水/疏水性质与表面分子与水之间的固/液界面相互作用自由能以及水介质中表面分子与空气之间的固/(液)/气界面相互作用自由能密切相关.水介质中固体表面与水之间存在范德华引力或疏水引力,与气泡之间存在范德华斥力、疏水引力以及静电斥力.在Lifshitz-范德华(LW)相互作用自由能、Lewis酸-碱(AB)相互作用自由能以及静电(EL)相互作用自由能3者之中,AB相互作用自由能比其它两者要大2～3个数量级以上.与固体表面能Lewis酸-碱分量相关的亲水指数√r_s~++√r_s~-可以成为衡量固体表面亲水/疏水性质的重要判据,水介质中固体表面疏水的必要条件是√r_s~++√r_s~-＜5mJ~(1/2)/m,指数大于或接近5mJ~(1/2)/m的表面必然是亲水的.     

低自由能固体表面的制备及其应用*

低自由能表面具有一些独特的性能,在工业和日常生活中具有广泛的应用,本文就低自由能表面的制备及其发展概况进行综述,共引用文献83篇。     

Pb-Al二元体系液-固界面自由能的热力学理论计算

以复杂的Warren二元及赝二元常规系统下的液-固界面自由能理论为基础, 借助Pb-Al二元体系为例对其进行简化, 获得了二元非混溶体系液-固界面自由能物理模型, 然后对其热力学公式进行推导, 得出只含两个参变量的理论公式, 并对几种温度下液-固界面自由能(γSL)计算值及用多相平衡(MPE)法得到的实验值作了对比. 结果表明, 改进的物理模型及理论公式易于理解、计算简便, γSL的计算值取决于温度及Al原子分数的两个参变量, 与实验值较好地吻合, 证明了该模型具有结构简单、精度较高的优点, 并可作为其它非混溶体系γSL的计算模型, 为其推广应用奠定基础.     

醋酸离子液体[C2mim][OAc]水溶液的摩尔表面Gibbs自由能

在288.15-318.15 K温度范围内测定了不同浓度离子液体1-乙基-3-甲基咪唑醋酸盐([C₂mim][OAc])水溶液的表面张力和密度;在改进李以圭等人的溶液表面张力模型基础上,提出摩尔表面Gibbs自由能新概念,建立了摩尔表面Gibbs自由能随溶液浓度变化的线性经验方程,利用这个经验方程估算了[C₂mim][OAc]水溶液的摩尔表面Gibbs自由能,并进一步预测了该溶液的表面张力,其预测值与相应的表面张力实验值高度相关并非常相似。由此可见,摩尔表面Gibbs自由能与等张比容极其类似,可能成为预测离子液体及其溶液性质的一种新的半经验方法。在指定溶液浓度下,根据溶液的摩尔表面Gibbs自由能随温度呈线性变化的规律,得到了新的Eötvös方程,与传统的Eötvös方程相比,新Eötvös方程的每一个参数都有明确的物理意义:斜率的负值是摩尔表面熵,截距是摩尔表面焓,在指定浓度的溶液中摩尔表面焓几乎不随温度变化。     

New Prediction Model of Surface and Interfacial Energies Based on COSMO-UCE**

The nature and strength of intermolecular and surface forces are the key factors that influence the solvation, adhesion and wetting phenomena. The universal cohesive energy prediction equation based on conductor-like screening model (COSMO-UCE) was extended from like molecules (pure liquids) to unlike molecules (dissimilar liquids). A new molecular-thermodynamic model of interfacial tension (IFT) for liquid-liquid and solid-liquid systems was developed in this work, which can predict the surface free energy of solid materials and interfacial energy directly through cohesive energy calculations based on COSMO-UCE. The applications of this model in prediction of IFT for water-organic, solid (n-hexatriacontane, polytetrafluoroethylene (PTFE) and octadecyl-amine monolayer)-liquid systems have been verified extensively with successful results; which indicates that this is a straightforward and reliable model of surface and interfacial energies through predicting intermolecular interactions based on merely molecular structure (profiles of surface segment charge density), the dimensionless wetting coefficient R_A/C can characterize the wetting behavior (poor adhesive (non-wetting), wetting, spreading) of liquids on the surface of solid materials very well.     

Graph‐theoretical identification of dissociation pathways on free energy landscapes of biomolecular interaction

Biomolecular association and dissociation reactions take place on complicated interaction free energy landscapes that are still very hard to characterize computationally. For large enough distances, though, it often suffices to consider the six relative translational and rotational degrees of freedom of the two particles treated as rigid bodies. Here, we computed the six‐dimensional free energy surface of a dimer of water‐soluble alpha‐helices by scanning these six degrees of freedom in about one million grid points. In each point, the relative free energy difference was computed as the sum of the polar and nonpolar solvation free energies of the helix dimer and of the intermolecular coulombic interaction energy. The Dijkstra graph algorithm was then applied to search for the lowest cost dissociation pathways based on a weighted, directed graph, where the vertices represent the grid points, the edges connect the grid points and their neighbors, and the weights are the reaction costs between adjacent pairs of grid points. As an example, the configuration of the bound state was chosen as the source node, and the eight corners of the translational cube were chosen as the destination nodes. With the strong electrostatic interaction of the two helices giving rise to a clearly funnel‐shaped energy landscape, the eight lowest‐energy cost pathways coming from different orientations converge into a well‐defined pathway for association. We believe that the methodology presented here will prove useful for identifying low‐energy association and dissociation pathways in future studies of complicated free energy landscapes for biomolecular interaction. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Study of Surface Cell Madelung Constant and Surface Free Energy of Nanosized Crystal Grain

1 INTRODUCTION 2. 1 Madelung constant of crystal Surface energy of crystal grain has crucial influ- The Madelung constant, which is used to calculate ence on the electrical and mechanical performances lattice energy and so on[1], is of central importance in of material, especially for material making up of na- the theory of ionic crystal and property of crystal nosized crystal grains because all outstanding per- structure. There is no special difficulty in calculating formances of the mat…     

吡啶基离子液体[C_6py][DCA]热力学性质及利用新E?tv?s方程预测其表面张力

制备了吡啶类离子液体N-己基吡啶二氰胺盐[C_6py][DCA],并用核磁共振氢谱(~1H NMR)、核磁共振碳谱(~(13)C NMR)、差热扫描量热(DSC)、傅里叶变换红外(FT-IR)光谱对其进行表征。在288.15–338.15 K温度范围内,采用标准加入法,测定其密度(ρ)、表面张力(γ)和折光率(n_D)。在测得的实验数据的基础上,得到了离子液体[C_6py][DCA]的分子体积(V_m)、表面能(E_a)、摩尔极化度(R_m)和极化率(α_p)。结果显示E_a、R_m和α_p几乎不随温度的变化而发生改变。本文还提出了摩尔表面Gibbs自由能(g_s)的概念,并改进了E?tv?s方程。同时还计算了gs、临界温度(T_c)和E?tv?s方程经验参数(kE),并预测了离子液体[C_6py][DCA]的表面张力,预测值与实验值具有较好的一致性。     

桥函数在统计力学积分方程理论3d-RISM-HNC的应用和溶剂化自由能计算的改进

把氢-桥函数和氧-桥函数应用于统计力学积分方程理论的三维的参考作用点-超链模型(3d-RISM-HNC)中,用以改进极性和非极性溶质的水溶液的热力学性质的计算.用三维和二维图形考察了溶剂水分子的氢原子和氧原子的桥函数在改进溶剂作用点的平均密度分布函数〈ρ_H(r)〉和〈ρ_O(r)〉,和平均超额化学势〈Δμ(r)〉的计算的效果.计算结果表明,氢桥函数和氧桥函数极大地改进了3d-RISM-HNC 方法的精度,把这一方法提高到定量和半定量的水平.研究表明,溶质分子的作用点的超额化学势的径向分布函数〈Δμ(r)〉比平均密度分布函数〈ρ_s(r)〉能够更灵敏地反映桥函数的改进效果.研究表明,为提高3d-RISM-HNC 方法的精度,需要进一步改进桥函数的函数形式和优化其中的参数.     

具有低表面自由能有机介电薄膜的制备及表征

通过自主开发的有机镀膜技术在Mg-Mn-Ce镁合金表面制备了具有低表面自由能和较高介电常数的有机纳米薄膜. 利用X射线光电子能谱(XPS)分析了表面有机镀膜过程的反应机理, 借助傅里叶变换红外(FT-IR)光谱进一步确认表面有机膜层的存在, 采用接触角测量仪测定了有机薄膜的蒸馏水接触角和表面自由能变化, 使用椭圆偏振光谱仪研究了薄膜的厚度, 并借助精密阻抗分析仪评价了薄膜的介电性能. 有机镀膜后镁合金表面形成了一层纳米级厚度的有机薄膜, 接触角从基体的70.8°上升至150.5°, 表面自由能从基体的37.96 mJ·m^-2降低到1.57 mJ·m^-2, 镁合金表面从亲水性转变为疏水性; 薄膜的厚度和质量随有机镀膜时间延长先增加后有所减小, 在镀膜20 min时薄膜性能最佳, 此时膜重达到23.5 μg·cm^-2, 膜厚最大为147.48 nm, 其相对介电常数也达到最大, 在1 kHz下可达24.922.     

Modification of Polymer Substrates with Low Surface Free Energy Material by Low‐Temperature Cured Polybenzoxazine

The B‐ala/AIBN PBZ system has a high extent of ring‐opening of oxazine because phenol‐containing oligomers are formed at the early stage of the curing process. As a result, the B‐ala/AIBN PBZ system possesses a relatively stronger intramolecular hydrogen bonding and lower surface energy than the pure B‐ala system at low temperature curing. In this context, poly(4‐vinyl pyridine), poly(4‐vinyl phenol) thin films and polycarbonate substrates, which lack liquid resistance, possess low surface free energy after modification with B‐ala/AIBN = 5/1 PBZ.