表面活性剂双水相界面性质的研究

表面活性剂双水相是指正、负离子表面活性剂混合水溶液在一定浓度及混合比 范围内，自发分离形成的两个互不相溶的水相。前文报道了将其作为一种新型萃取 体系，用于生物活性物质的分离。目前有关其相行为、化学物质和生物大分子的分 配方面已有较多研究，但未见两相之间界面化学性质研究的报道。表面活性剂双水 相的形成是一种奇特的相分离现象，两个稀水溶液（含水量可高达99%以上）互不 相溶、平衡共存，其界面结构和界面张力必有其特殊性。     

Local Structures and Chemical Properties of Deprotonated Arginine

The potential energy surface of gaseous deprotonated arginine has been systematically in- vestigated by first principles calculations. At the B3LYP/6-31G(d) level, apart from the identification of several stable local structures, a new global minimum is located which is about 6.56 kJ/mol more stable than what has been reported. The deprotonated arginine molecule has two distinct forms with the deprotonation at the carboxylate group (COO^-). These two forms are bridged by a very high energy barrier and possess very different IR spectral profiles. Our calculated proton dissociation energy and gas-phase acidity of argi-nine molecule are found to be in good agreement with the corresponding experimental results. The predicted geometries, dipole moments, rotational constants, vertical ionization energies and IR spectra of low energy conformers will be useful for future experimental measurements.     

Thermodynamic Properties of Aqueous Glucose–Urea–Salt Systems

In this work, the thermodynamic behavior of aqueous solutions containing the solutes NaCl, glucose, and/or urea is investigated. These substances are vital components for living bodies and further they are main components of blood serum. Osmotic coefficients were determined by cryoscopic measurements in single-solute and multi-solute aqueous solutions containing salts (NaCl, KCl, CaCl₂), glucose, and/or urea. The results show that NaCl determines the osmotic coefficients in the urea/glucose/NaCl/water system. Investigation of the effect of different salts on osmotic coefficients revealed ion-specific effects. At physiologically important solute concentrations in typical blood serum solutions, the osmotic coefficients were found to be in the range of 0.90–0.93. In a second step, the state of water in different glucose/salt/water and urea/salt/water systems was investigated. Depending on the kind of salt, the chemical potential of water in urea/salt/water is either higher or lower than in glucose/salt/water systems at equal nonelectrolyte concentrations. This result was found to be independent of the salt molality. Finally, the investigated systems were modeled with the Pitzer model and the ePC-SAFT equation of state, which allowed predicting of the properties of these multi-solute aqueous solutions.     

含氯化钠电解质水溶液体系热力学性质研究进展

总结了近几十年来含氯化钠电解质水溶液体系热力学性质的研究成果及其在盐湖、地下卤水、油田水和海盐制备等领域的应用,并对含钠水盐体系在不同温度下的热力学性质进行了总结,对于推动含钠水盐体系电解质溶液理论的发展和促进富盐湖卤水、地下卤水及海水的开发利用具有重要的意义。     

十二烷基硫酸钠水溶液的动态表面吸附性质

利用MPTC型气泡压力张仪研究了十二烷基硫酸钠(SDS)溶液在不同NaCl 浓度下的动态表面吸附性质, 分析了离子型表面活性剂在表面吸附层和胶束中形成双电层结构产生表面电荷对动态表面扩散过程和胶束性质的影响. 结果表明, SDS在表面吸附过程中, 表面电荷的存在会产生5.5 kJ·mol^-1的吸附势垒(E_a), 显著降低十二烷基硫酸根离子(DS^-)的有效扩散系数(D_eff). 十二烷基硫酸根离子的有效扩散系数与自扩散系数(D)的比值(D_eff/D)仅为0.013, 这表明SDS与非离子型表面活性剂不同, 在吸附初期为混合动力控制吸附机制. 加入NaCl可以降低吸附势垒. 当加入不小于80 mmol·L^-1 NaCl后, E_a小于0.3 kJ·mol^-1, D_eff/D在0.8-1.2之间, 表现出与非离子型表面活性剂相同的扩散控制吸附机制. 同时, 通过分析SDS胶束溶液的动态表面张力获得了表征胶束解体速度的常数(k₂). 发现随着NaCl 浓度的增大, k₂减小, 表明SDS胶束表面电荷的存在会增加十二烷基硫酸根离子间的排斥力, 促进胶束解体.     

Coarse-grained Dynamics Simulation in Polymer Systems: from Structures to Material Properties

Polymers are widely used in our daily life and industry because of their intrinsic characteristics, such as multi-functionality, low cost, light mass, ease of processability, and excellent chemical stability. Polymers have multiscale space-time properties, which are mainly reflected in the fact that the properties of polymer systems depend not only on chemical structure and molecular properties, but also to a large extent on the aggregation state of molecules, that is, phase structure and condensed state structure. Thanks to the continuous development of simulation methods and the rapid improvement of scientific computation, computer simulation has played an increasingly important role in investigating the structure and properties of polymer systems. Among them, coarse-grained dynamics simulations provide a powerful tool for studying the self-assembly structure and dynamic behavior of polymers, such as glass transition and entanglement dynamics. This review summarizes the coarse-grained models and methods in the dynamic simulations for polymers and their composite systems based on graphics processing unit(GPU) algorithms, and discusses the characteristics, applications, and advantages of different simulation methods. Based on recent studies in our group, the main progress of coarse-grained simulation methods in studying the structure, properties and physical mechanism of polymer materials is reviewed. It is anticipated to provide a reference for further development of coarse-grained simulation methods and software suitable for polymer research.     

水溶液纳米簇模型对水溶液性质的理解探讨

针对大学化学中的水溶液平衡问题,在宏观热力学分析的基础上结合现代科学发展对水溶液纳米簇进行了结构研究和模型的科学验证,引入微观结构分析,增强学生在原子、分子层面上对水溶液的性质的理解,保证教学的先进性。     

Local Structures in Aluminum Oxide

Abstract

The relative stability of sixfold and fourfold coordination for Al ions by oxygens in the solid and liquid phases of Al₂O₃ is examined by treating several small clusters of this material within an ionic model.     

气/液界面上十六烷基三甲基溴化铵水溶液的动态表面性质

用最大泡压法测定了不同温度下浓度低于cmc时十六烷基三甲基溴化铵水溶液的动态表面张力.发现当浓度低于0.10 mol·m-3时动态吸附量ΓT遵s从由Henry吸附等温式导出的动态表面状态方程.在浓度位于0.10至0.80mol·m-3的较大范围内,Tt遵从从Langmuir等温式导出的动态表面状态方程.在吸附的后期十六烷基三甲基溴化铵分子在溶液表面上的吸附遵从混合动力学控制机理.从表观扩散系数计算出吸附为混合动力学控制机理时吸附能垒为6.7～7.1 kJ·     

Structures and Unexpected Dynamic Properties of Phosphine Oxides Adsorbed on Silica Surfaces

Solid‐state NMR spectroscopy of selected phosphine oxides adsorbed on silica surfaces establishes the surface mobilities, even of phosphine oxides with high melting points. Crystal structures of the adducts Ph₃PO ? HOSiPh₃ and Cy₃PO ? H₂O indicate that the interactions with silica involve hydrogen bonding of the P?O group to adsorbed water and surface silanol groups.     

不同结构烷基苯磺酸钠水溶液的泡沫性能及动态表面张力

研究了一系列直链三取代和支链双取代烷基苯磺酸钠水溶液的动态表面张力(DST)和泡沫性能, 考察了分子结构变化对烷基苯磺酸钠水溶液的DST和泡沫性能的影响. 探讨了动态表面张力参数(t*, n, R1/2)的变化规律及其与泡沫性能的关系. 结果表明, 随着取代烷基链长度增加, t*和n值增大, R1/2减小, 动态表面活性降低. 由于双取代支链烷基苯磺酸钠分子具有特殊的柔性长支链, 使得吸附膜排列紧密、膜弹性增大, 因而其泡沫稳定性明显优于多取代直链烷基苯磺酸钠的稳定性. 在气流法产生泡沫的过程中, 动态表面张力是控制起泡高度的关键因素.     

Formation of Vesicles and Micelles in Aqueous Systems of Tetrameric Acids as Determined by Dynamic Light Scattering

A comprehensive dynamic light scattering (DLS) study on the system BP10Na₄/water is presented. BP 10Na₄ is a tetrameric fatty acid in sodium form. In order to change molecular packing conditions both electrolyte (NaCl) and alcohol (1-butanol, 1-pentanol) are added to the surfactant system. Phase diagrams of the systems reveal not only an extensive micellization, but also the occurrence of a lamellar liquid crystalline D phase. The DLS study shows an existence of vesicles at very dilute BP10Na₄ concentrations ( ?cmc) and also a co-existence of micelles and vesicles at higher BP10Na₄ concentrations. Cryo-TEM pictures verify the existence of the vesicles. Based on the DLS and SLS experiments the weight-average molar mass of the micelles are estimated to be 13500 g/mol at 100 mM NaCl and 22700 g/mol at 600 mM. The corresponding aggregation numbers are 13 and 22, respectively.     

Novel Vesicular Aqueous Two-Phase Systems

Aqueouspolymertwo-phase(APTP)systemsandpartitioningofvariousmaterialsinthemhavebeeninvetigated,whichhavebeenutilizedinanalysisandseparationofchemicalandbiochemicalmaterialsl'2.InthelasttwodecadessurfactantshavebeenfOundveryusefulinanalysisandseparation,basedonitsphasebehavior3.Usuallythecloudpointphenomenonofnonionicsurfactantwasutilized.Phaseseparationalsooccursindiluteaqueoussolutionofmixedcationicandanionicsurfactants,fOrmingco-.-existingtwodiluteaqueoussolutions'-6.Thisphenomenaofphases…     

Interfacial Polycondensation in Aqueous and Non-Aqueous Systems

Abstract

Interfacial polycondensation in aqueous and non-aqueous systems has been investigated in order to synthesize various polyamides having functional groups. Rigid aromatic polyamides having pyridine moieties (PPy) were synthesized by interfacial polycondensation using an aqueous system and the solution properties of PPy in concentrated sulfuric acid were investigated in terms of solution viscosity and lyotropic behavior. Interfacial polycondensation in a non-aqueous system using two immiscible solvents was found to be useful for the synthesis of aromatic polyesters and copolyesters.     

Visible-light-switchable Chalcone-Flavylium Photochromic Systems in Aqueous Media

The chalcone-flavylium photochromic system switches in aqueous media. However, the chalcone→flavylium conversion requires detrimental ultra-violet (UV) light for the switching which deters their applications in the biological domain. To address this issue, we have synthesized strategically modified chalcone scaffolds that can be reversibly switched to the flavylium forms with visible light ranging from 456 nm (blue) to 640 nm (red).     

A New Gibbs Energy Model for Obtaining Thermophysical Properties of Aqueous Electrolyte Solutions

In this paper, a new Gibbs energy model is proposed to study the thermophysical properties of aqueous electrolyte solutions at various temperatures. The proposed model assumes that the electrolytes completely dissociate in solution. The model also has two temperature-independent adjustable parameters that were regressed using experimental values of the mean ionic activity coefficients (MIAC) for 87 electrolyte solutions at 298.15 K. Results from the proposed model for the MIAC were compared with those obtained from the E-Wilson, E-NRTL, Pitzer and the E-UNIQUAC models, and the adjustable model parameters were used directly to predict the osmotic coefficients at this temperature. The results showed that the proposed model can accurately correlate the MIAC and predict the osmotic coefficients of the aqueous electrolyte solutions better on the average than the other models studied in this work at 298.15 K. Also, the proposed model was examined to study the osmotic coefficient and vapor pressure for a number of aqueous electrolyte solutions at high temperatures. It should be stated that in order to calculate the osmotic coefficients for the electrolyte solutions, the regressed values of parameters obtained for the vapor pressure at high temperatures were used directly. The results obtained for the osmotic coefficients and vapor pressures of electrolyte solutions indicate that good agreement is attained between the experimental data and the results of the proposed model. In order to unequivocally compare the results, the same experimental data and same minimization procedure were used for all of the studied models.     

Tapping of Granular Packs: A Model Based on Local Two-Level Systems

Two-level systems are known to be important for the low-temperature properties of glasses. We suggest here that they might explain some remarkable properties of powders under repeated tapping, as discovered by the Chicago group. Following the ideas of S. F. Edwards, the relevant variables here are (1) the volumes V(alpha) (V(beta)) occupied in the states alpha, beta (including distant reorganizations); (2) the magnitude B of the "activated volume" during a transition from alpha to beta; (3) the analog of temperatures, i.e., the compactivity (or free volume) v. Tapping induces alpha-->beta transitions, and these in turn reduce the compactivity. At low tapping strengths GammaGamma>Gamma(*)), the system freezes before reaching the alpha-beta equilibrium, and the density grows with the observed logarithmic law. At higher tapping strengths (Gamma相似文献