在NaCl和HTAB共存条件下甲基纤维素溶液凝胶化行为

利用流变仪研究了甲基纤维素(MC)溶液在NaCl、十六烷基三甲基溴化铵(HTAB)以及两者共存下MC溶液的凝胶化行为,发现其凝胶化温度随着NaCl浓度的增加而下降,随着HTAB浓度的增加而上升;但是MC/NaCl的凝胶化温度保持不变,与HTAB浓度 无关,而MC/HTAB溶液的凝胶化温度则随着NaCl浓度的增加而下降．以上的实验结果表明,在NaCl存在下,HTAB将被诱导形成胶束,因此MC/NaCl的凝胶化温度保持不变;反之,当NaCl不存在时,HTAB将优先吸附到MC上而不会在溶液中形成胶束,尽管其浓度     

SDS胶束溶液在石油类污染物荧光光谱测量中的应用

提出了一种以十二烷基硫酸钠(SDS)胶束溶液为溶剂增溶、增敏、增稳石油类物质的新方法。研究了石油类物质的荧光强度随SDS胶束溶液浓度的变化规律,确定了其溶剂SDS胶束溶液的最佳浓度为0.1 mol·L-1。使用FLS920荧光光谱仪测量得到不同稀释浓度的汽油、柴油、煤油SDS胶束溶液的三维荧光光谱矩阵(EEMs),分析了瑞利(Rayleigh)散射、拉曼(Raman)散射以及仪器光谱特性对测量光谱的影响,经过光谱校正,建立了三种油的SDS胶束溶液在激发波长为250～400 nm、发射波长为260～500 nm范围内的三维荧光光谱图,并确定了在一定浓度范围内荧光强度与浓度具有良好的线性关系。在相同条件下,用同样的方法配制各种浓度汽油、柴油、煤油水溶液作对比,验证了SDS胶束溶液作为石油类物质的溶剂可以使水中石油类物质的溶解度增加、荧光强度增大、稳定性更好,实现了石油类物质可以不依赖于某些有毒溶剂萃取,又解决了其水中溶解度低不宜定量的问题。     

Effect of Short Chain Alcohols upon Viscosity of TTAB Solution

研究了不同条件下乙醇、丙醇和丁醇对十四烷基三甲基溴化铵(TTAB)溶液粘度行为的影响． 结果表明, 在无KBr存在下,TTAB溶液相对粘度随着醇的加入线性增加,说明醇分子没有增溶到TTAB胶束之中;在KBr存在下,TTAB溶液相对粘度随着乙醇的加入不断减小,但是会随着丙醇和丁醇的加入出现最大值,说明丙醇和丁醇的加入会促进TTAB胶束的增长;在KCl存在下,丙醇和丁醇的加入对TTAB胶束的影响几乎可以忽略不计．一种可能的解释是：KBr的存在促进了TTAB胶束的增长．因此,TTAB胶束内核的疏水程度有所增加,导致在特定浓度条件下丙醇和丁醇溶解到胶束中进一步促进了TTAB胶束的增长．     

Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB

采用水溶液均聚合方法,制备了阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵(AMC14AB)的均聚物,使用荧光探针法、表面张力测定及电导测定法,重点考察了均聚物P(AMC14AB)在水溶液中的胶束化行为与表面吸附现象. 在水溶液中,均聚物P(AMC14AB)呈现单分子链胶束的聚集形态,具有零临界胶束浓度,从开始加入P(AMC14AB)起,水溶液中随即产生单分子链胶束,不存在Krafft温度. P(AMC14AB)在溶液表面也发生表面吸附,使水的表面张力下降,即P(AMC14AB)也具有表面活性;随着浓度增大,表面吸附量增大,水的表面张力持续下降;当表面吸附达饱和时,表面张力～浓度曲线上出现突变点,该点定义为饱和的表面吸附浓度,而不应该再称为临界胶束浓度. P(AMC14AB)单分子链胶束溶液对疏水有机物(甲苯)的增溶情况,明显不同于普通小分子表面活性剂十六烷基溴化铵(CTAB)的多分子胶束溶液,甲苯增溶量～P(AMC14AB)浓度的关系曲线上无突变点,而且对甲苯的增溶能力高于CTAB的多分子胶束溶液.     

表面活性剂溶液粗粒化模型couette流动模拟

本文主要利用粗粒化分子动力学方法对不同浓度下表面活性剂水溶液在couette流动过程中胶束的形成、速度分布与流变性规律进行了研究。结果表明,对于相同浓度的表面活性剂溶液,随着剪切速率的增大,胶束完全动态平衡时间越来越小;而随着表面活性剂分子浓度的增加,胶束动态平衡时间也越来越小,形成胶束越来越快。在剪切速率与溶液剪切黏度关系方面,保持表面活性剂分子浓度不变情况下,随着剪切速率的增大,剪切黏度逐渐减小,呈现剪切稀化特征。     

HP-β-CD消除SDS对SDBS同步荧光光谱的影响

十二烷基苯磺酸钠(SDBS)与十二烷基苯磺酸钠(SDS)之间的相互作用,能对SDBS的检测产生明显干扰。实验结果表明,在水溶液中SDS不仅可以增大SDBS的同步荧光强度,还能显著降低SDBS的表观临界胶束浓度。按SDBS的摩尔计量比加入1∶1的羟丙基-β-环糊精(HP-β-CD),可以消除SDS对SDBS的同步荧光强度的干扰。相比于形成胶束,在SDS/SDBS水溶液中,SDBS单体优先选择与HP-β-CD形成量比1∶1的包结物。当水溶液中HP-β-CD的浓度由0增加至0.900 mmol·L~(-1)时,复配体系中SDBS形成胶束的标准摩尔吉布斯函变ΔγGθm由-39.681 k J·mol-1增加至-37.580 k J·mol~(-1)。加入适量HP-β-CD后,能够准确检测SDS/SDBS水溶液中SDBS的含量(临盘采油厂T5站地层水样),方法的回收率为101.0%~101.6%。FT-IR及1H-NMR分析表明,SDBS分子进入HP-β-CD分子内腔的大口径端并形成量比1∶1的包结物,是消除SDS对SDBS检测干扰的根本原因。     

水溶性聚合物与十二烷基硫酸钠相互作用的1H NMR研究

用¹H NMR方法研究了分别在2 g/L聚乙烯吡咯烷酮(PVP)和2 g/L聚乙烯醇（PVA）存在下，一系列不同浓度的十二烷基硫酸钠(SDS)溶液. 二维NOESY实验表明，SDS在浓度为2.5 mmol/L时形成胶束，且PVP被增溶到胶束内部；当SDS浓度低于2.5 mmol/L时，PVP与SDS之间没有明显的相互作用. 自旋-自旋弛豫时间的测量结果支持这一结论. 实验中没有检测到PVA与SDS之间的相互作用.     

表面活性剂SDS/TX-100混合体系的NMR研究

用NMR测量了不同比例的SDS/TX-100混合溶液中质子化学位移,结合表面活性剂溶液的两态交换模型,分析了质子化学位移随浓度的变化趋势, 求出了不同比例混合溶液中两种表面活性剂各自的临界胶束浓度及混合胶束的临界胶束浓度. 依据理想混合溶液理论,预测了混合胶束的临界胶束浓度,计算了溶液中SDS与TX-100之间的相互作用参数和SDS在混合胶束中的摩尔分数. 根据所得参数讨论了混合胶束的形成过程. 利用文中和文献中混合体系的实验数据验证了协同作用理论改进前后的适用性,表明改进后的协同作用理论完善一些.     

油酸钾对不同温度下阳离子瓜儿胶水溶液流变行为影响

实验测定了阳离子瓜儿胶水溶液的流变行为,讨论了油酸钾对其流变行为的影响．稳态剪切实验结果表明,加入油酸钾后,瓜儿胶溶液的零切黏度增加了近三个数量级,出现类似凝胶的性质．动态剪切实验结果表明,瓜儿胶溶液表观模量则随着油酸钾浓度的增加而增加,储存模量和损失模量对应的剪切模量随着油酸钾浓度的增加而减小．事实上,随着油酸钾浓度的增加,高分子交联在一起的聚集体数量逐渐减小,强度逐渐增加．温度的影响刚好相反,随着温度的升高,聚集体的数量逐渐增加,强度逐渐减小．     

阴离子表面活性剂存在下氯化血红素光解动力学研究

利用罗丹明B(RhB)-H₂O₂化学发光体系及流动注射技术,研究了十二烷基磺酸钠(SDS)存在下,氯化血红素在紫外光下的光解反应动力学规律,并与不加入SDS时氯化血红素光解行为进行了对比。 结果表明：SDS存在与否,氯化血红素的光解行为均符合一级动力学反应方程。 但是加入SDS后所形成的胶束相,减缓了氯化血红素的光解速度,提高了其光稳定性。     

Micelles of poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) terpolymers in aqueous media and their interaction with surfactants

Well-defined poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) (PI-P2VP-PEO) triblock terpolymers were synthesized by anionic polymerization high-vacuum techniques. The terpolymers formed spherical three-layer (onion-type) micelles in neutral and acidic pH aqueous media as evidenced by static and dynamic light scattering. In pure water, kinetically frozen micelles with a core composed of a soft PI inner part and a hard P2VP outer shell and protected by a neutral PEO corona were formed. In acidic media the core was formed by the soft PI hydrophobic segment, whereas the corona consisted of an inner cationic polyelectrolyte P2VPH⁺ part and an outer PEO shell. The aggregation numbers were found to be high in all cases, due to the high hydrophobicity of the core-forming blocks. In the latter case an increase in size was observed due to the electrostatic repulsions between the P2VPH⁺ chains in the inner part of the corona, which is also responsible for the lower aggregation numbers observed in the acidic solutions. The interaction of these onion-type micelles with cationic (DTMAB) and anionic (SDS) surfactants led to the formation of mixed polymer/surfactant aggregates. Their structural characteristics could be varied by combining changes in surfactant type and concentration, solution pH and type of electrostatic interaction, leading to interesting, block-copolymer-based, environmentally responsive colloidal systems.     

Circular dichroism and viscosity studies of gelatin with anionic surfactant,SDBS

The interaction of SDBS in aqueous gelatin solutions is studied above the gelation temperature by viscosity and circular dichroism (CD) measurements. The steep rise in the relative viscosity of the system could be due the structural transitions leading to micellar growth of higher orders, which is supported by CD measurements. The circular dichroism spectra indicated that gelatin helped in inducing the sphere → rod transition, without suffering any conformational changes within it. The large changes in viscosity over the concentration range studied points to the strong molecular interactions in gelatin–SDBS system and its dependence on [SDBS]. CD spectra showed an increase in ellipticity, suggesting that the micelle can either bind intra molecularly, i.e. within a gelatin molecule, or it can bind cooperatively with two or more molecules to form a large complex. The findings are particularly significant in terms of the head group contribution, hydrophobic interaction and formation of formulated complexes.     

Dielectric relaxation studies of alkanols solubilized by sodium dodecyl sulphate aqueous solutions

Considerable attention has been paid in recent years to the influence of alcohols on ionic micellar structures, alcohol co-surfactants most commonly employed in the preparation of microemulsions. Dielectric relaxation spectroscopy (DRS) is a versatile tool to monitor the dynamic process of such micellar systems. We report here the changes in the dielectric constant of the medium and the relaxation time of micellar solutions of sodium dodecyl sulphate (SDS) in water in the presence and absence of alkanols—hexan-1-ol, octan-l-ol, decan-l-ol and 1,2-ethanediol. The time domain dielectric data were obtained in the reflection mode in the frequency range of 10 MHz to 20 GHz using a HP54750A sampling oscilloscope and HP 54754A TDR plug-in-module. The sample is held at 303 K in a SMA cell with an effective pin length of 1.35 mm. We have determined the relaxation time (τ) using the Cole–Cole method. The relative viscosity ηr on the micellar solutions were also determined. The result shows that the dielectric constant increases linearly with SDS concentration in pure aqueous solutions up to 400 mM and decreases thereafter. The relaxation times are of the order of 15 ps to 25 ps and are far greater than that of Debye rotational relaxation of the monomer species. It is assigned to the dispersion step to water molecules surrounding to hydrophobic particles or the “bound water”. The addition of alcohols results in a linear increase in relaxation time in all the systems. As the concentration of SDS increases τ/ηr attains a near constant value showing that solubilization becomes more difficult at these concentrations. Our results show that the alcohol molecules are solubilized at the surface of the SDS micelle (i.e.) the micelle–water interface.     

Effect of hydrophobicity of cationic carbocyanine dyes DiOC<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> on their binding to anionic surfactant micelles

The interaction of a series of cationic dialkyloxacarbocyanine perchlorate (DiOC _n ) dyes of different degrees of hydrophobicity with micelles of an anionic surfactant, sodium dodecylsulfate (SDS), has been studied spectrophotometrically in aqueous solutions. The Benesi–Hildebrand equation was used to calculate binding constants (K _b ) of the dyes to surfactant micelles, the fraction of dye bound to the micelles (f _mic ), and the standard free-energy change (ΔG ⁰) for the transfer of dye from the aqueous to micellar phase. It has been shown that the interaction of oppositely charged dye molecules and surfactant micelles is controlled by both electrostatic and hydrophobic interactions. A small increase in dye hydrophobicity due to lengthening of the hydrocarbon radical has been shown to cause an abrupt nonlinear increase of the fmic value. This points to a key role of hydrophobic interactions in the binding of dye molecules with the micelles.     

Cesium adsorption in hydrated iron oxide particles suspensions: an NMR study

137Cs is an important component of nuclear waste which may pollute water. Its migration in natural environments is slowed down by adsorption on minerals. Cesium adsorption on akaganeite (beta-FeOOH) particles, dextran-coated ferrihydrite (5 Fe(2)O(3)-9H(2)O) particles, and ferritin in aqueous solutions is studied with (133)Cs nuclear magnetic resonance measurements. The longitudinal relaxation time (T(1)) of (133)Cs in the presence of such magnetic particles depends on whether the ions bind to the particle or not. T(1) of (133)Cs ions in aqueous solutions containing the same amount of magnetized particles will not depend on cesium concentration if relaxation is governed by diffusion (when cesium is not able to bind), but it will depend on cesium concentration if exchange governs relaxation (when cesium is able to bind). The method is successfully tested using TEMPO, a nitroxide stable free radical whose relaxation is due to diffusion. (133)Cs relaxation in solutions of ferritin, akaganeite, and dextran-coated ferrihydrite particles is found to result from a cationic exchange of cesium ions between particles surface and bulk ions, owing to adsorption. The effect of pH on (133)Cs relaxation in solutions of the particles is consistent with the adsorption properties of cations on hydrated iron oxides.     

Rheological Behavior of Some Cationic Polyelectrolytes

The rheological behavior of some cationic polyelectrolytes in aqueous solution is presented. The polyelectrolytes under study consist of polycations that have positive charges (N,N-dimethyl-2-hydroxypropylenammonium chloride) located along the main chain with or without nonpolar side chains (PCA₅D₁ and PCA₅, respectively). This investigation mainly considers the influence of oscillation frequency and temperature on their rheological behavior in salt-free aqueous solution at three polymer concentrations (c_p = 2%, 4%, and 6%) as well as in the presence of low molar mass salt (NaCl). The results indicate the main effect of these parameters was to modify the hydrophobic interactions between the side nonpolar groups of the modified polyelectrolyte. The comparison between the complex viscosity values, at the same polymer concentration, c_p = 4%, for PCA₅D₁ and PCA₅ shows higher values in the whole interval of temperatures under study and a pseudoplastic behavior at temperatures greater than 50°C for the former system.     

正十二烷基硫酸钠在聚丙烯酰胺溶液中聚集的1H NMR研究

利用核磁共振自旋-晶格弛豫时间（T₁）、自旋-自旋弛豫时间（T₂）、自扩散系数（D）以及二维核Overhause增强谱（2D NOESY）技术研究了表面活性剂正十二烷基硫酸钠（SDS）在聚丙烯酰胺（PAM）浓度固定为10 g/L水溶液中的聚集. 结合与SDS水溶液体系核磁共振实验数据比较,得到了如下信息：（1） 当溶液中有PAM存在时,SDS分子的运动性下降,临界聚集浓度提前;（2） 随着SDS浓度的增加,PAM分子的自扩散性能下降,同时分子链的柔软性也下降了;（3） 2D NOESY谱结果表明,PAM与SDS分子间未发生直接的缔合作用.     

Isentropic compressibility, effective pressure, classical sound absorption and shear relaxation time of aqueous lithium bromide, sodium bromide and potassium bromide solutions

Densities, speeds of sound and viscosities of aqueous lithium bromide, sodium bromide and potassium bromide solutions were measured as functions of concentration (0.0085≤m (mol kg⁻¹)≤14.06) and temperature (273.15≤T(K)≤323.15). Allied properties like isentropic compressibilities, effective pressure, classical sound absorption and shear relaxation time were calculated by using the measured data. The interaction in these three bromide solutions vary in the order of NaBr>KBr>LiBr. The primary hydration shells are saturated at 10.8, 5.1 and 5.8 mol kg⁻¹ with 5.1, 10.9 and 9.6 number of water molecules in the primary hydration shell of lithium bromide, sodium bromide and potassium bromide solutions respectively. The cationic environment is found to influence the hydration phenomena of the anion.

The non-Arrhenius temperature dependence of shear relaxation time were analysed by using the Vogel-Tammann-Fulcher (VTF) equation. The concentration dependence of shear relaxation time is different in these three bromide solutions. Such an effect is attributed to the competitive effects of hydrogen bonding, structure forming/breaking effect of ions and the formation of ion pairs.     

The aqueous reference for ESR oximetry

The interaction of molecular oxygen with derivatives of nitroxide EPR spin labels has been investigated using nuclear spin-relaxation spectroscopy in aqueous and nonaqueous solvents. The proton spin-lattice relaxation rate induced by oxygen provides a measure of the local concentration of oxygen, which we find is dependent on solvent. In water, the hydrophobic effect increases the local concentration of oxygen in the nonpolar portions of solute molecules. For nitroxides reduced to the hydroxylamine in aqueous solutions, we find that the local concentration of oxygen is approximately twice that associated with a free diffusion hard sphere limit, while in octane, this effect is absent. These results show that nitroxide based ESR oximetry may suffer a reference concentration shift of order a factor of two if the aqueous nitroxide spectrum or relaxation is used as the reference.     

Viscosity of Collagen Solutions: Influence of Concentration,Temperature, Adsorption,and Role of Intermolecular Interactions

An investigation of the influences of the adsorption, electrolyte, shear rate, and temperature on the viscometric behavior of collagen solutions was performed using a photoelectric viscometer. The experimental results showed an abnormal behavior of the reduced viscosity (η_sp/C) of dilute collagen solutions measured by a viscometer with or without a hydrophobic surface treatment; the reduced viscosity increased with decreasing concentration. This phenomenon can be completely eliminated by increasing the concentration of an added salt. It indicated that the abnormal viscosity resulted from a long-ranged, inter-molecular electrostatic force. The reduced viscosity decreased as the shear rate increased. The shear-thinning cavitation phenomenon resulted from the high aspect ratio of the collagen molecules. The reduced viscosity of the collagen solutions increased with an increase in temperature, which was due to the association of collagen molecules at high temperature.