系列烷基芳基磺酸盐在水溶液中胶束化的焓-熵补偿现象

以表面张力法研究了系列烷基芳基磺酸盐在水溶液中胶束化的热力学性质,并考察了温度与分子结构对胶束化的影响.结果表明,烷基芳基磺酸盐在水溶液中胶束化是一个自发过程,主要来自熵驱动;随着温度升高,先有利于胶束化而后又不利于胶束化,且熵变对吉布斯自由能变的贡献有下降趋势,而焓变的贡献有增大趋势;胶束化存在焓-熵补偿现象,补偿温度Tc均在(306±2)K,基本不随烷基芳基磺酸盐的分子结构的改变而变化;随着芳环上短烷基链或长烷基链碳数的增加,胶束化能力和胶束的稳定性均提高,而随着芳环向长烷基链中间位置移动,胶束化能力和胶束的稳定性均下降.     

β-环糊精与两性表面活性剂相互作用β

用表面张力法研究了β-环糊精与十一烷基酰胺甲酸钠(C11H23CONHCOONa,SF)两性表面活性剂在不同温度下的包结作用。结果表明:SF的表面张力值(β)及表观临界胶束浓度(cmc)加入β-CD后增加,β-CD浓度越大,γ和cmc增加越多,且SF的cmc与β-CD浓度存在线性关系,随温度的升高,两性表面活性剂的表面张力值降低,意味着它们的表面活性随温度升高而增强。利用表面张力测定了β-CD-SF体系在不同温度下的包结形成常数Ka,进而求得了包结过程的焓变和熵变,结果表明,该过程是焓和熵均有利的过程,进一步说明疏水作用是形成包结物最重要的的作用力之一。     

自由能微扰法研究系列烷基芳基磺酸盐的胶束化焓-熵补偿现象

为了研究不同结构的表面活性剂分子在水溶液中的胶束化焓-熵补偿现象, 采用自由能微扰(FEP)法计算了系列烷基芳基磺酸盐的溶剂化自由能, 并根据胶团化过程的质量作用模型讨论了相关热力学性质. 结果表明: 自由能微扰法得到的溶剂化自由能大小与用传统热力学表面张力法测定的吉布斯自由能相近, 能够用于比较不同结构的烷基芳基磺酸盐间胶束化能力; 烷基芳基磺酸盐在水溶液中的胶束化过程是自发进行的, 且存在焓-熵补偿现象, 补偿温度范围均在(302±2) K; 随着分子结构中芳环向长烷基链中间位置移动, 胶束化能力和胶束的稳定性均下降; 而随着芳环上短烷基链或长烷基链碳数的增加, 形成胶束的能力与稳定性均提高.     

β-环糊精与两性表面活性剂相互作用

用表面张力法研究了β-环糊精与十一烷基酰胺甲酸钠(C₁₁H₂₃CONHCOONa,SF)两性表面活性剂在不同温度下的包结作用。结果表明:SF的表面张力值(β)及表观临界胶束浓度(cmc^*)加入β-CD后增加,β-CD浓度越大,γ和cmc^*增加越多,且SF的cmc^*与β-CD浓度存在线性关系,随温度的升高,两性表面活性剂的表面张力值降低,意味着它们的表面活性随温度升高而增强。利用表面张力测定了β-CD-SF体系在不同温度下的包结形成常数K_a,进而求得了包结过程的焓变和熵变,结果表明,该过程是焓和熵均有利的过程,进一步说明疏水作用是形成包结物最重要的的作用力之一。     

含酯基Gemini表面活性剂在有机醇-水体系中的胶束热力学及聚集行为

采用电导法研究了不同温度下含酯基Gemini表面活性剂在纯水和在质量分数为10%的甲醇-水(MAWR),乙二醇-水(EG-WR),丙三醇-水(GL-WR)四种体系中的集聚行为和胶束热力学;聚集行为参数包括临界胶束浓度(cmc)和抗衡离子的解离程度(α)以及胶束的热力学参数,包括标准吉布斯自由能(ΔG_m~o)、吉布斯迁移自由能(ΔG_(trans)~o)、吉布斯烷基链胶束化自由能(ΔG_(tail)~o)、标准焓变(ΔH_m~o)和标准熵变(ΔS_m~o),均被计算和讨论。研究表明在所有的研究体系中,cmc值随着疏水链的增加而减小,随着加入的醇结构中羟基数目的增加而增大,随温度的升高先变小,后变大呈U字形;胶束化过程都是自发进行的,并且在293.15 K下,胶束化过程是吸热的,在293.15 K上,胶束化过程是放热的;通过稳态荧光光谱法研究了表面活性剂在纯水、有机醇-水混合溶液中的微极性,结果表明,在相同溶剂中,随着烷基链长度的增加,溶液微环境的疏水性越强;对于相同的Gemini表面活性剂,随着加入含羟基数目越多的醇,其微环境的疏水性越强。并研究了Gemini表面活性剂在混合体系中形成胶束过程的焓-熵补偿曲线。     

液相色谱过量热力学函数变化规律性探讨

本文从溶液热力学和色谱理论推导出过量热力学函数与色谱参数间的关系, 测定了苯的同系物在液-液分配过程中, 过量焓变等函数与流动相组成、样品碳数的线性关系,并求得经验方程式. 同时研究了不同样品焓变和熵变的线性补偿规律. 并试图从溶液理论进行计算.     

脂肪族α-氨基酸疏水自缔合作用的流动微量热法研究

建立了水溶液中脂肪族α- 氨基酸疏水自缔合相互作用的化学模型, 根据模型方程对由精密流动微量热法测得的α- 氨基酸水溶液的稀释焓数据进行回归分析, 得到等步自缔合作用的平衡常数(K)、焓变(ΔHm)和熵变(ΔSm)等热力学参数, 发现焓、熵之间存在很好的补偿关系. 同时计算了溶液中水的偏摩尔过量熵(SE1), 并根据脂肪族α- 氨基酸的水化模型对结果进行了讨论. 建立的化学模型参数能在一定程度上解释McMillan- Mayer模型中的同系焓作用系数的物理意义.     

DMF/水溶液中TDBAC与咪唑型离子液体混合胶束的聚集行为及热力学性质

利用电导法研究了298.15 K时十四烷基二甲基苄基氯化铵(TDBAC)与咪唑型离子液体表面活性剂Cn mim Br(n=12,16)混合胶束性质,考察了极性溶剂N,N-二甲基甲酰胺(DMF)对TDBAC/C16mim Br混合体系胶束化的影响。结果表明,混合体系在水溶液和DMF水溶液中都存在协同效应。随DMF体积分数的增加,TDBAC/C16mim Br混合体系临界胶束浓度(cmc)增大,而反离子结合度减小。利用胶束理论模型计算了混合胶束的组成、相互作用参数和活度系数,以及胶束形成混合自由能、混合熵和超额自由能等热力学函数。随DMF体积分数增加,协同作用下降,胶束形成的自发性降低。水溶液中混合胶束形成是焓效应与熵效应共同作用的结果,而在20%DMF水溶液中,胶束形成是熵驱动。     

谈化学热力学状态函数的运用

由物质的生成焓、熵可得化学反应的焓变、熵变,再由吉布斯自由能变△rGθm判断反应的倾向.     

表面活性素分子结构对其胶束化行为的影响

采用表面张力、界面张力、荧光、动态光散射(DLS)和冷冻刻蚀电镜(FF-TEM)等方法, 研究了由Bacillus subtilis HSO121所产生的一组表面活性素的胶束化行为. 通过对表面活性素溶液表面张力、表面活性素对水/正己烷界面张力的影响、表面活性素胶束微极性以及胶束粒径和形态的研究, 发现随着表面活性素脂肪链长度的增加, 其表界面活性增强, 溶液中趋向于形成更大的聚集体.     

Adsorption and micelle formation of alkylammonium chloride-alkyltrimethylammonium chloride mixtures

The surface tension of the aqueous solutions of binary cationic surfactant mixtures of (1) dodecylammnonium chloride (DAC)-tetradecyltrimethylammonium chloride (TTAC), (2) decylammonium chloride (DeAC)-dodecyltrimethylammonium chloride (DTAC), and (3) DAC-DTAC was measured as a function of the total molality and composition of surfactants at 298.15 K. The compositions of surfactants in the adsorbed film and micelle were evaluated and the phase diagram of adsorption and that of micelle formation were constructed. Furthermore the excess Gibbs energies of adsorption and micelle formation were calculated to estimate the deviation from the corresponding ideal mixing. It was found that the surface and micelle are enriched in trimethylammonium salts in (1) and (2), while in ammonium salt in (3) compared to the bulk solution. On the other hand, the micelle is enriched in trimethylammonium salts compared to the surface at the critical micelle concentration (CMC) in all the systems. The miscibility of the surfactants was clarified from the standpoints of the structure of the head group and of the matching between the size of polar head group of surfactants and the difference in hydrocarbon chain length.     

Synthesis and properties of quaternary ammonium Gemini surfactants with hydroxyl groups

The article describes synthesis of four hydroxyethyl alkylene–double alkyl bromide through substitution of nucleophilic d iethanolamine, 1-bromododecane, and 1,4-dibromobutane. The structure of the new hydroxyl cationic surfactant (HDCS) was characterized by ¹H NMR and FTIR spectra. The aqueous solution of HDCS showed critical micelle concentration, i.e., 5.6 × 10^?2 mM, and could reduce oil/water interfacial tension to 3.28 × 10^?3 mN m^?1. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), adsorption efficiency (pC₂₀), and effectiveness of surface tension reduction (Π_CMC). In addition, maximum surface excess concentration (Г_max) and minimum surface area/molecule (A_min) at the air/water interface were obtained by the Gibbs adsorption isotherm. The influence of inorganic salts (sodium chloride, calcium chloride) and organic salts (sodium benzoate) on the surface tension of HDCS in aqueous solution was investigated. For wettability alteration measurement, contact angle measurement as a quantitative method was utilized. Meanwhile, foam ability, foam stability, and emulsifying property of the synthesized surfactant were also examined at different concentration. HDCS also had excellent viscosity property.     

Effect of salts on local mobility and rheological properties of micelles of new long-chain surfactant

The effects of organic (sodium salicylate) and inorganic (KCl) salts on the rheological properties of micellar solutions and the local characteristics (local mobility and ordering) of micelle cores is studied for a cationic surfactant containing a long (C₁₈) unsaturated alkyl radical. The polar head of the surfactant contains two hydroxyl groups. The local characteristics are determined employing spin probe ESR spectroscopy. It is shown that the incorporation of a salt into a micellar solution reduces the local mobility of radicals of surfactant molecules in micelle cores and increases their local Lordering and the viscosity of the solution. Sodium salicylate has a stronger influence on the solution viscosity and the local characteristics of micelle cores than KCl does. Variations in the local characteristics of micelle cores under the action of the salts are in close correlation with variations in the rheological properties of the micellar solutions.     

对硝基苯酚丙酸酯水解反应的CTAB胶团催化作用研究

 在Na2CO3-NaHCO3缓冲溶液中,测定了对硝基苯酚丙酸酯(NPP)的十六烷基三甲基溴化铵(CTAB)胶团催化反应的表观活化能和活化参数; 考察了无机盐(NaCl, NaBr, Na2SO4)对该催化反应的影响. 结果表明: 无机盐的加入,主要产生压缩CTAB胶团双电层、降低OH-离子的胶团表面浓度以及减小NPP的加溶程度的双重减速效应. 反离子浓度(或活度)愈高及水合反离子半径愈小,则减速效应愈明显.     

Synergistic interactions between zwitterionic surfactants derived from olive oil and an anionic surfactant

Abstract

The surface properties of the mixtures of zwitterionic surfactants derived from olive oil (carboxylbetaine-OCB and sulfobetaine-OSB) and anionic surfactant-sodium dodecylbenzene sulfonate (SDBS) at different mole fractions were investigated by surface tension measurement. The influences of the addition of inorganic salts (NaCl, MgCl₂) on the surface activities in OCB/SDBS and OSB/SDBS systems were also studied. The result shows that the two mixed systems possess lower CMC values and higher surface activities over all mole fractions studied than their individual components. Meanwhile, the noticeable synergistic interactions of OCB/SDBS and OSB/SDBS were determined by the micelle interaction parameter (β^m) according to regular solution theory. It is observed that the mixed OCB/SDBS system at α_OCB?=?0.6 and the mixed OSB/SDBS system at α_OSB?=?0.6 exhibit the strongest synergism. In addition, the binary surfactant mixtures performed better surface activities upon addition of inorganic salts and the different valence state of mental ions of the inorganic salts had different surface ability effect on the mixed system: Mg²⁺?>?Na⁺.     

胆盐与磷酸钙的相互作用

胆汁的pH条件下(pH=6～8)，应该生成无定形磷酸钙(ACP)，而在胆结石中磷酸钙通常以羟基磷灰石的形式出现.利用谱学方法研究了ACP与胆盐的作用.结果表明，胆盐以胶团的形式与ACP作用，在溶液中形成复合胶团，使其溶解度增加.不同类型胆盐与ACP的作用能力不同：脱氧胆酸钠(NaDC) > 牛磺胆酸钠(NaTC) > 胆酸钠(NaC).胆盐与ACP中结合钙的亲和能力大于结合钙的亲和能力，使ACP在胆汁的环境下容易转化为羟基磷灰石.     

胶团噻唑衍生物对安息香不对称合成反应的催化作用

通过α-(1-萘基)-N-硫代甲酰乙胺与卤代酮反应制得六个光学活性的4-烷基-3-α-(1-萘基)乙基噻唑溴化物烷基碳链长=1,2,7.11,15,21). 将其用于催化水溶液中的安息香缩合反应, 所得产物收率约20-30%具有较高的光学纯度(47-57%). 在各种缓冲溶液中测定了S(+)-4-甲基-3-α-(1-萘基)乙基噻唑氯化物(Ta)的胶团性质和由它催化的不对称安息香缩合反应. 临界胶团浓度(cmc)证明(Ta)在反应中确以胶团形式催化. 在硼砂溶液中, 安息香的收率高达61%, 光学纯度23.6%.     

Surface-active, micellar, and antielectrostatic properties of bis-ammonium salts

A series of new cationic surfactants, bis-quaternary ammonium dibromides, were synthesized. The properties of these surfactants were characterized by surface tension measurements, conductivity study, and dynamic light scattering. The surface properties, such as surface excess concentration, Gamma(cmc), surface area demand per molecule, A(min), efficiency in surface tension reduction, pC(20), the effectiveness of surface tension reduction, gamma(min), critical micelle concentration, cmc, and standard free energy of micellization, DeltaG(mic)(0) and DeltaG(ads)(0), were obtained by means of surface tension measurements. The antielectrostatic properties were investigated by measuring the surface resistance, the half-charge decay time, and the maximum voltage induced on polyethylene films and propylene unwoven fabrics. Critical micellar concentrations (cmc) of investigated salts were much lower than those of the monomeric salt DTAC. The results obtained in this work were compared to analogous bis-quaternary ammonium dichlorides and well-known gemini cationic surfactants. It was found that the type of counterion had an impact on the values of the micelle ionization degree and the hydrodynamic diameters. Larger aggregates were found for bis-quaternary ammonium dibromides, which had smaller values of the ionization micelle degree than bis-quaternary ammonium dichlorides. Moreover, the antielectrostatic effect strongly depended on the kind of counterion. All investigated salts had very good antistatic properties.     

Solubilization and precipitation of cholesterol in aqueous solution of bile salts and their mixtures

Solubilization of cholesterol by mixed micelles of sodium chenodeoxycholate with sodium ursodeoxycholate was investigated in carbonate-tetraborate buffer (Kolthoff) solution at pH 10 and 37°C. It was found that the mixing of the two bile salts gives a negatively synergetic effect on solubilization of cholesterol. The solubilizing power of bile salts for cholesterol was remarkably influenced with the change in mole fraction of sodium ursodeoxycholate (X _UDC).The behavior of bile salt solutions saturated with cholesterol was examined by measuring the surface tension. Two break points were observed in the curves of surface tension vs. concentration. The break points seem to correspond to a CMC in the absence of solubilized cholesterol and another CMC in the presence of solubilized cholesterol inside bile salt micelle.