Bulk Properties of Carboxymethylchitosan and Cationic Surfactant Mixtures: Fluorescence and Surface Tension Studies

The interactions between carboxymethylchitosan and alkyltrimethylammoniumbromides were studied in aqueous solution. The dependences of aggregation behavior on surfactant concentration, polyelectrolyte concentration, as well as surfactant chain length were investigated mainly using fluorescence spectroscopy method. The variation of I ₁/I ₃ of pyrene fully characterized the aggregation behavior of the polymer-surfactant complex. Meanwhile, based on that Nile red has the sensitivity to the environmental polarity different to pyrene, the changes of aggregates size and number can be reflected by the fluorescence spectroscopy of Nile red.     

Dynamic Surface Elasticity of Polyelectrolyte/Surfactant Adsorption Films at the Air/Water Interface: Carboxylmethylchitosan and Cetyltrimethylammonium Bromide

The dynamic surface elasticity of the solution of carboxymethylchitosan (CMCH) and cetyltrimethylammonium bromide (C₁₆TAB) was measured as a function of the surfactant concentration and the surface age by the oscillating drop method. The results showed that the surface layer of the CMCH/C₁₆TAB solution transformed from loose to structured with the increase in the surfactant concentration. The surface elasticity versus the surface pressure curve during the adsorption showed different features at different surfactant concentration ranges, which was connected with the structural transformation of the surface layer. Our results show that the measurement of dynamic surface dilational properties is a powerful tool for studying the surface kinetics, which is helpful for dealing non-equilibrium systems in industry.     

卤化钠对一种新型阳离子表面活性剂动态表面张力的影响

The equilibrium and dynamic surface tension （DST） of the novel cationic surfactant, 3-（p-nonylphenoxy）-2-hydroxylpropyl trimethyl ammonium bromide, abbreviated as RTAB, were studied. The effect of sodium halide such as NaCl, NaBr and NaI on the DST behavior of the RTAB solution below its CMC was studied in detail. Due to the preferential adsorption, the effect of hydration and salting out, the ability to reduce the DST values at the same concentration was in the order of NaI〉NaBr〉NaCl. Attributed to its high surface activity, the equilibrium time of the DST of the surfactant solution was insensitive to the ionic strength.     

含氟表面活性剂溶液的动态表面张力研究

本文研究了阳离子氟表面活性剂CF₃CF₂CF₂O(CF(CF₃)CF₂O)₂CF(CF₃)CONH(CH₂)₃N⁺(C₂H₅)₂CH₃I^-(简写FC-4 )的动态表面性质，利用Krüss K12和MBP动态表面张力仪分别测定了该体系的平衡表面张力和动态表面张力。由平衡表面张力测定结果得到了临界胶束浓度和表面吸附量。利用渐进的Ward and Tordai方程对动态数据进行了分析。结果表明：在吸附的最初阶段符合扩散控制模型，而在吸附的后期，证明了吸附势垒的存在，表明在吸附后期属于混合动力学模型。计算得出25 ℃时，该体系势垒约在25到35 kJ/mol. 由于氟表面活性剂分子间作用力小，表面压是导致吸附势垒的主要原因。     

一种磺酸聚醚型表面活性剂的制备及动态表面张力

通过3-氯-2-羟基丙磺酸钠(NaCHPS)和1-氯-3-丁氧基-2-丙醇(CBP)之间溶液共缩聚,合成了一种新型磺酸聚醚表面活性剂—环氧丙磺酸缩水甘油丁基醚共聚物。采用红外、核磁等测试技术对其结构进行了表征。测定了不同质量浓度、不同结构的磺酸聚醚水溶液的动态表面张力(DST),并用Rosen经验方程对DST进行了分析。结果表明,磺酸聚醚的数均分子量为900～1 600,其溶液浓度越高,DST达到介平衡越快,则DST分析曲线越低;当质量浓度从56．4 mg/L增大到3 611 mg/L时,R_(1/2)值从11．04 mN/(m·min)增大到7 662．5 mN/(m·min);磺酸聚醚的动态表面活性随着磺酸聚醚中CBP含量的增加而增强。     

Dynamic Surface Tension and Adsorption Mechanism of Surfactant Benzyltrimethylammonium Bromide at the Air/Water Interface

The air‐solution equilibrium tension, γ_c and dynamic surface tension, γ_t, of aqueous solutions of a novel ionic surfactant benzyltrimethylammonium bromide (BTAB) were measured by Wilhelmy method and Maximum bubble pressure method (MBPM), respectively. Adsorption equilibrium and mechanism of BTAB at the air‐solution interface were studied. The CMC was determined to be 0.11 mol/L. The results show that at the start, the adsorption process is controlled by a diffusion step. Toward the end, it changes to a mixed kinetic‐diffusion controlled mechanism with the adsorption activation energy of about 11.0 KJ/mol. Effects of temperature, inorganic salts, and alcohols on adsorption kinetics also are discussed.     

SDS及其与十二烷基三乙基溴化铵混合体系在矿化水中的表面活性

测定了十二烷基硫酸钠(SDS)、十二烷基三乙基溴化铵(DTEAB)单一体系及不同摩尔比的混合体系在矿化水溶液中的表面活性,并与在纯水和NaCl水溶液中的表面活性作了比较．所得结果表明：(1)阴离子表面活性剂SDS在含Ca^2 ,Mg^2 等的矿化水中有比在纯水和NaCl水溶液中更好的表面活性．这一方面是由于矿化水中的Ca^2 ,Mg^2 对负电胶团和表面吸附层的强烈电性作用,另一方面在大量Na^ 存在时,钠钙盐混合表面活性剂Krafft点提高不多;(2)SDS和DTEAB混合物在矿化水中具有很强的增效作用,其表面活性的变化规律与在纯水和NaCl水溶液中基本相同,表明阴阳离子表面活性剂混合体系具有优异的抗矿化水性能．这些结果可用阴、阳表面活性离子的电性作用解释．     

十八烷基二甲基氯化铵水溶液动态表面张力及吸附动力学研究

使用最大气泡法测定了十八烷基二甲基氯化铵（C_(18)DAC）水溶液的动态表 面张力,考察了浓度、温度等对其DST的影响,详细表征了DST随时间的变化过程, 计算了动态表面张力的各种参数（n,t_i,t~*,t_m,R_(1/2)）。结合Word- Tordai方程计算了表观扩散系数（D_a）和吸附势垒（E_a）,对其吸附动力学模式 进行了研究,探讨了DST参数的物理意义。结果表明,t~*值越小,吸附势垒E_a越 大,宏观扩散系数D_a越小,表面活性剂分子越不易吸附在溶液表面;C_(18)DAC低 浓度时吸附属于扩散控制模式,高浓度时属于混合控制模式;高浓度时,在吸附初 期（t → 0）为扩散控制模式,吸附后期（t → ∞）为混合控制模式。     

表面活性剂溶液动态表面张力及吸附动力学研究

本文简介了动态表面张力的定义、测定方法及吸附动力学,对非离子、阴离子、阳离子及两性表面活性剂溶液动态表面张力的研究情况进行了总结,重点讨论了浓度、温度、添加剂及化学结构因素对动态表面张力的影响.     

Yukawa流体的相平衡和界面张力研究

应用二阶微扰理论, Duh-Mier-Y-Teran状态方程和在平均球近似(mean spherical approximation, MSA)的基础上获得的直接相关函数, 建立了适用于均匀流体和非均匀流体的状态方程. 结合此状态方程, 重整化群理论(renormalization group theory, RG)和密度泛函理论(density functional theory, DFT), 分别研究了Yukawa流体的相平衡和界面张力. 结果与分子模拟数据吻合良好.     

表面活性剂与聚合物相互作用的动力学模拟

用扩散颗粒动力学模拟方法（Dissipative Particle Dynamics，DPD）模拟了 中性聚合物与离子型表面活性剂的相互作用。在分子水平上研究了介于微观和宏观 上的一些性质，直观地用三维图形描绘了聚合物在表面活性剂溶液中的聚集形成， 并通过聚合物的末端的变化表征了聚集过程。结果发现：随着表面活性剂浓度的增 加，聚合物呈现自由伸缩→形成松散的棒状结构→再出现胶束状珍珠链结构→最终 在六角状和层状相中分布的过程。DPD模拟方法能够直观地得到聚合物在表面活性 剂溶液中的聚集形态。     

全氟丁基磺酸钠与辛基三乙基溴化铵的相互作用

通过测定辛基三乙基溴化铵(C8H17N(CH2CH3)3Br,C8NE)与全氟丁基磺酸钠(C4F9SO3Na,C4F)组成的不同混合比的碳氢-碳氟正负离子表面活性剂混合体系的表面张力,得到不同摩尔比时C8NEC4F体系的临界胶束浓度(cmc)、cmc处的表面张力(γcmc)、总饱和吸附量、不同表面张力时表面吸附层的组成,利用Gibbs-Duhem方程求得cmc处的胶团组成。 采用规则溶液理论计算了胶团中分子间相互作用参数(βm),并求得cmc以上的胶团组成。 实验表明,C8NEC4F复配体系的cmc远远小于单体系的cmc,这也体现在该体系的βm负值很大,胶团内分子相互作用很强。 但是C4F与C8NE复配后γcmc较C4F单体系的变化幅度不是特别大(γcmc降低2~4 mN/m),这是由于C8NEC4F碳链的不对称性导致部分C8NE的碳链在溶液表面弯曲而覆盖了C4F端基CF3基团。 表面吸附层中氟表面活性剂相对于本体溶液是富集的,即使对于C8NE大大过量的体系,表面吸附层组成也在等摩尔附近;对于C4F过量的体系,C4F在表面吸附层中的比例比溶液中的略高。 随着表面张力的降低,表面吸附层的组成相对更偏向于氟表面活性剂。 cmc处的胶团组成随着体系中C4F含量的增大偏向于形成显著富含C4F的胶团,对于C8NE大大过量的体系,胶团组成接近等摩尔。 cmc之后的胶团组成接近等摩尔,主要归因于此时静电相互作用占主导,这和溶液配制过程中发现复配体系超过cmc一定浓度后就易生成沉淀的现象是相符的。     

One Pot Synthesis of Amphiphilic Hyperbranched Poly-(amino ester)and Its Dynamic Surface Activity

Amphiphilic hyperbranched poly(amino ester)s with hydrophilic multi‐ethoxylated triacrylate backbone and hydrophobic long alkyl side chain were firstly synthesized via one pot Michael addition polymerization. The poly‐(amino ester) could dissolve in cold water and self‐assemble into loose micelle. Under 50–1000 ms bubble, the dynamic surface tension (DST) of the poly(amino ester) aqueous solution (0.5 wt%) still maintained in the range of 32–28 mN/m. The aqueous solutions of poly(amino ester)s with different molecular weights showed the lower critical solution temperature (LCST) in the range of 8–50°C, which could also be tuned by its pH. Capped with hydrophobic groups on the terminal units and partially neutralized with acid, the poly(amino ester)s still kept their stable dynamic surfactant behaviors, indicating promising application.     

烷基聚葡糖苷溶液的表面吸附平衡与动力学

用吊片法和气泡最大压力法分别测定了烷基聚葡糖苷(APG)C₉.₆G_1.3水溶液的平衡和动态表面张力,研究了APG水溶液表面的吸附平衡、动力学及其影响因素.测得其cmc(临界胶束浓度)为0.032g/L.吸附过程由初始的扩散控制转变到势垒控制,吸附势垒为4～7kJ/mol.温度升高,平衡和动态表面张力均减小,吸附量增加;加入无机盐,平衡和动态表面张力增大,吸附量亦增加;醇类的吸附使动态表面张力下降速率加快,表明APG与醇分子间有协同吸附作用.     

表面活性剂溶液的动表面张力研究

用振荡射流法分别测定了不同温度下全氟辛酸、十二烷基硫酸钠、二聚氯乙烯正辛醇醚溶液(浓度低于CMC)的动表面张力,讨论了它们的表面吸附动力学,研究结果表明都是扩散控制。     

Reconstruction of Covalent Organic Frameworks by Dynamic Equilibrium

Covalent organic frameworks (COFs) are periodic two‐ or three‐dimensional polymeric networks with high surface areas, low density, and designed structures. Because COFs are normally prepared based on reversible formation of covalent bonds with relatively weak stability, their structures can be easily broken or damaged due to changes in the surrounding environment. Thus, developing strategies to realize the reconstruction of COFs in order to extend their usage lifetime is crucial for practical applications. In addition, exploring the kinetics of COF growth under varied reaction conditions is important for better understanding the nucleation and growth processes of COFs. In this work, the reformation mechanism of an imine‐based COF using an ex situ characterization method was investigated, disclosing an interesting COF reconstruction progress from disorder to order. The present study shows the regeneration ability of COFs, and the developed method could be generalized for broader use in the field.     

亚稳平衡吸附态与亚稳平衡系数关系的热力学研究

在相同温度、压力、pH值和离子强度等条件下,同一种金属离子在无机矿物表面上发生的吸附反应可以形成能量不同的吸附状态(如Zn可以边-边和角-角两种方式吸附在水锰矿表面上),因而反应终了时吸附质可处于不同的亚稳平衡吸附态(MEA).应用MEA理论,针对吸附反应A+H₂O=xA₁+yA₂+H₂O,推导出实际吸附反应“平衡常数”(Kreal)与亚稳平衡系数(Kme)的热力学关系式,从理论上分析了吸附反应MEA状态的变化对实际吸附反应平衡性质的影响.分析结果表明,Kme值与两种MEA状态之间的能量差呈指数关系,通过影响吸附反应的MEA状态(包括能量和组成)的反应动力学因素可影响吸附平衡常数和吸附等温式(线)等吸附热力学性质.     

阴、阳离子表面活性剂混合体系在硅胶/水及硅胶/矿化水界面上的吸附

研究阴、阳离子表面活性剂混合体系(十二烷基氯代吡啶,辛基磺酸钠,辛基三乙基溴化铵/十二烷基苯磺酸钠)在硅胶,纯水和硅胶,矿化水界面上的吸附作用,探讨阴(阳)离子表面活性剂的存在对阳(阴)离子表面活性剂吸附作用的影响．结果表明,阴离子表面活性剂的存在基本不影响阳离子表面活性剂在带负电固体表面的吸附;而阳离子表面活性剂的存在却使本来吸附量就不大的阴离子表面活性剂在带负电的固体表面上不再吸附．在矿化水中阳离子表面活性剂的吸附量比在纯水中明显降低．从硅胶表面吸附机制解释了所得结果．     

A Nonpolar,Nonamphiphilic Molecule Can Accelerate Adsorption of Phospholipids and Lower Their Surface Tension at the Air/Water Interface

The adsorption dynamics of a series of phospholipids (PLs) at the interface between an aqueous solution or dispersion of the PL and a gas phase containing the nonpolar, nonamphiphilic linear perfluorocarbon perfluorohexane (PFH) was studied by bubble profile analysis tensiometry. The PLs investigated were dioctanoylphosphatidylcholine (DiC₈‐PC), dilaurylphosphatidylcholine, dimyristoylphosphatidylcholine, and dipalmitoylphosphatidylcholine. The gas phase consisted of air or air saturated with PFH. The perfluorocarbon gas was found to have an unexpected, strong effect on both the adsorption rate and the equilibrium interfacial tension (γ_eq) of the PLs. First, for all of the PLs, and at all concentrations investigated, the γ_eq values were significantly lower (by up to 10 mN m^?1) when PFH was present in the gas phase. The efficacy of PFH in decreasing γ_eq depends on the ability of PLs to form micelles or vesicles in water. For vesicles, it also depends on the gel or fluid state of the membranes. Second, the adsorption rates of all the PLs at the interface (as assessed by the time required for the initial interfacial tension to be reduced by 30 %) are significantly accelerated (by up to fivefold) by the presence of PFH for the lower PL concentrations. Both the surface‐tension reducing effect and the adsorption rate increasing effect establish that PFH has a strong interaction with the PL monolayer and acts as a cosurfactant at the interface, despite the absence of any amphiphilic character. Fitting the adsorption profiles of DiC₈‐PC at the PFH‐saturated air/aqueous solution interface with the modified Frumkin model indicated that the PFH molecule lay horizontally at the interface.