磁场对苯胺电聚合的影响

本文研究了外加磁场对苯胺电聚合过程的影响。在Ｈ２ＳＯ４介质中，当磁场方向垂直电极表面时，在０．５８Ｔ处聚合速度最大，约为磁场影响下的２倍；当磁场方向平行电极表面时，随磁场强度的增加聚合速度也增大，在０．７Ｔ时约为无磁场影响下的２．４倍；膜的成核生长是在动力学控制下的二维瞬时成核过程。此外，在ＨＣｌ、ＨＣｌＯ４、ＨＢＦ４介质中，也观察到磁场的增强现象。     

表面活性剂的电喷雾质谱分析

采用不同的质谱采集模式分析了不同类型的表面活性剂。阳离子表面活性剂如氯化十二烷基二甲基苄基铵,适合正离子采集模式,准分子离子为其阳离子;阴离子表面活性剂如十二烷基苯磺酸钠,适合负离子采集模式,准分子离子为其阴离子;两性表面活性剂如氧化十四烷基二甲基胺,适合负离子采集模式,准分子离子为[M-H]^-;非离子表面活性剂如壬基酚聚氧乙烯（12）醚,适合正离子采集模式,准分子离子为[M＋Na]^-。     

可聚合表面活性剂的研究进展

在乳液聚合中，表面活性剂发挥着非常关键的作用，但同时它们也存在不足的方面，一个比较有前景的方法就是使用可聚合表面活性剂。可聚合表面活性剂以牢固的共价键键合到聚合物粒子上，有效避免了表面活性剂的解析及其在膜中的迁移。本文综述了近年来可聚合表面活性剂的进展，主要讨论了阴离子、非离子、阳离子可聚合表面活性剂的特征和性质及其在乳液聚合中的应用。     

阳、阴、非离子表面活性剂胶束对酯碱性水解的影响

应用紫外分光光度法和热动力学方法研究了芳香酸酯和正脂肪酸酯在表面活性剂ＤＴＡＢ、ＴＴＡＢ、ＣＴＡＢ、ＳＤＳ、Ｂｒｉｊ３５、ＴｒｉｔｏｎＸ－１００胶束中的碱性水解反应。阳、阴、非离子表面活性剂胶束对酯的碱性水解均有禁阻作用。讨论了胶束对酯碱性水解禁阻作用的原因。     

表面活性剂对亲水性颗粒悬浮液流变性的影响

研究表面活性剂对悬浮液流变性的影响,对于表面活性剂在悬浮体系中的应用有着重要意义。实验研究了3种不同类型的表面活性剂对亲水性颗粒悬浮液流变性的影响,并利用激光共聚焦显微镜以及Zeta电位仪等仪器对表面活性剂影响悬浮液流变性的原因进行探究与阐述。结果表明,只有阴离子表面活性剂十二烷基苯磺酸钠对亲水性颗粒悬浮液的流变性有显著的影响,随着十二烷基苯磺酸钠的质量分数从0.1%增加到0.6%,悬浮液的状态由类似液体状态变为类似膏体状态,再变为类似液体状态。根据研究结果,当利用十二烷基苯磺酸钠溶液制备的悬浮液呈类似膏体状态时,颗粒表面带正电,且观察到胶束在颗粒周围环绕,此时阴离子表面活性剂胶束和颗粒在静电吸引力的相互作用下形成网状结构。利用非离子表面活性剂聚氧乙烯月桂醚以及阳离子表面活性剂十六烷基三甲基溴化铵溶液制备悬浮液时,胶束在悬浮液中并无在颗粒表面聚集的行为,悬浮液的流变性无明显变化。     

电聚合苯胺过程的在线紫外-可见光谱

用在线紫外-可见光谱电化学的方法对0.5mol/L硫酸水溶液中苯胺在ITO导电玻璃电极上的电化学聚的过程进行了研究.结果表明在循环伏安条件下苯胺发生了电聚合,聚合速率与苯胺浓度成正关系;而且在线紫外-可见电化学光谱表明,在0.01mol/L苯胺溶液的电聚合过程的诱导期较长.恒电位条件下的在线紫外-可见电化学光谱显示苯胺浓度为0.05mol/L,电位为0.8V时,在ITO电极上苯胺低聚合物中间体可能产生于聚苯胺形成之前;而0.01mol/L苯胺在0.8V电位下不发生聚合,但在线紫外-可见光谱又显示此时在电极上可能存在小的苯胺低聚物的中间体;在线紫外-可见光谱表明这种中间体是可能产生并存在电极表面上的.     

表面活性剂复配混合胶束对酯碱性水解反应的影响

应用紫外分光光度法和热动力学法研究了芳香酸酯和正脂肪酸乙酯在表面活性剂复配事胶束（ＳＤＳ－Ｂ３５，ＤＴＡＢ－Ｂｒｉｊ－３５，ＴＴａｂ－Ｂｒｉｊ３５，ＣＴＡＢ－Ｂｒｉｊ３５，ＣＢＡＢ－Ｔｒｉｔｏｎ Ｘ－１００，ＳＤＳ－Ｔｒｉｔｏｎ Ｘ－１００）中的碱性水解反应，复配胶束对酯的碱性水解反应起禁阻作用，其禁阻作用比单一胶束的禁阻作用强，并讨论了复配胶束对酯碱解起禁阻作用的原因。     

表面活性剂在胶束电动力学色谱中的应用

系统地综述了活性剂在MEKC中的应用,阐述了不同种类表面活性剂的混合表面活性剂胶束体系的特征和应用范围,也对表面活性剂浓度的优化策略作了初步探讨。引用文献56篇。     

新型可聚合双季铵盐阳离子表面活性剂的合成与表征

合成了新型可聚合的单季铵盐阳离子表面活性剂(PMQ)和双季铵盐阳离子表面活性剂(PDQ)。其结构经1HNMR和元素分析表征。在25℃的中性水溶液中PMQ和PDQ的临界胶束浓度分别为25.1mmol·L-1和32.4mmol·L-1,对应的表面张力分别为37.8mN·m-1和40.95mN·m-1。     

表面活性剂胶束形状随浓度转变的核磁共振研究

运用核磁共振一维氢谱和自扩散实验方法研究了聚乙烯乙二醇异辛酚醚(TX-100)、十二烷基苯磺酸钠(SDBS)和十四烷基三甲基溴化铵(TTAB)三种不同类型的表面活性剂在重水溶液中的胶束形状转变, 发现它们在临界胶束浓度以上的各自相应浓度都有胶束形状的变化(由球状转变为椭球状或棒状). 在常温常压和没有其他添加剂的情况下, 表面活性剂溶液浓度高于其临界胶束浓度时, 球状胶束开始形成. 核磁共振一维氢谱和自扩散实验的结果显示, 当溶液浓度继续增加到一定程度时, 溶液中表面活性剂分子的化学位移和自扩散系数的变化速率都有明显的转折, 这说明溶液中球状胶束开始发生转变. 进一步通过仔细分析对比核磁共振一维氢谱中各基团谱峰, 发现表面活性剂胶束亲水表面上的质子的化学位移变化速率要远高于其疏水内核中的质子, 据此推测胶束形状很可能由球状转变为椭球状或棒状.     

Surfactant equilibria and its impact on penetration into stratum corneum

Anionic surfactant penetration into the skin and their subsequent interactions with stratum corneum lipids and proteins has historically been linked with irritation and dryness from the use of soaps, body washes, facial cleansers, shampoos, and other rinse-off personal care products. Mechanisms of surfactant penetration into the skin surface has been a topic of debate for decades. In this review, we discuss relevant theories of surfactant penetration into skin as well as interactions of surfactants with skin components. We present evidence that thermodynamic analyses of surfactant solution equilibria can be useful in modeling these behaviors. A theory of surfactant monomer penetration into stratum corneum is proposed.     

阳离子表面活性剂和有机酸混合水溶液的热响应特性

用稳态和动态流变学方法研究了阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和有机酸3-甲基水杨酸(3MS)的混合水溶液随浓度和温度变化的流变特性。在加热过程中混合溶液呈现三种不同类型的温度响应。其中最有趣的是,当3MS的浓度在80与100 mmol·kg^-1之间时,有浅蓝色的稀溶液出现。随着温度的升高,样品由浅蓝色溶液转化成透明的粘弹性溶液,同时聚集态从囊泡转变成长的蠕虫状胶束,且开始转化的温度随溶液中3MS浓度的增加而升高。利用流变温度扫描和电导率测定对此转变进行了验证。定性解释这个转化是因为在高温下吸附的3MS分子从囊泡上解吸被溶解到水相中。     

表面活性剂对分散体系粘度影响的特殊性

通过液体石蜡的水基化分散对影响分散体系粘度的粒子大小、表面活性剂胶束和界面膜等因素进行了研究.结果表明,表面活性剂胶束对分散体系粘度的影响极为有限,而在分散相粒子界面上由表面活性剂分子所形成的界面膜是导致分散体系粘度产生变化的重要因素.实验数据表明,对于分散体系的稳定性,存在一个表面活性剂浓度变化的临界值,而该临界值所对应的是表面活性剂分子在粒子表面以最紧密和规整的方式形成的界面膜,该种界面膜使分散体系粘度达到最大值,从而最大限度地保证了分散体系的稳定性.     

Nucleation and growth mechanism for the electropolymerization of aniline on highly oriented pyrolytic graphite at higher potentials

In this work, the nucleation and growth mechanism for the electropolymerization of aniline was investigated at higher potentials on highly oriented pyrolytic graphite by potentiostatic current-time transient and atomic force microscopic (AFM) measurements. The electrochemical data fitted to the theoretical curves for the nucleation and growth suggest that electropolymerization of aniline follows the three-dimensional growth and progressive nucleation mechanism. These results were also compared with the results obtained at lower potentials. The results obtained from transient analysis, at higher potentials, were in good agreement with the results of AFM images. Electronic Publication     

Effect of copolymer structure on micellar behavior of acrylamide-octylphenylpoly (oxyethylene) acrylate surfactant

Acrylamide-octylphenylpoly (oxyethylene) acrylate copolymer (AM-C₈PhEO_nAc) surfactant is the copolymer of acrylamide (AM) and octylphenylpoly (oxyethylene) acrylate macromonomer (C₈PhEO_nAc). The effect of the copolymer structure on the micellar behavior in aqueous solution was studied using dynamic light scattering. It has been found that the length of ethylene oxide (EO) in the branch and the content of C₈PhEO_nAc in the copolymer surfactant have great effects on the size and distribution of the micelles. For AM-C₈PhEO₇Ac copolymer, at the concentration of 5 × 10⁻⁴ g/ml, the micellar size increases with the increase of C₈PhEO₇Ac content. However, for AM-C₈PhEO₁₀Ac copolymer, the result is the opposite; the micellar size decreases with the increase of C₈PhEO₁₀Ac content. Larger C₈PhEO_nAc content leads to narrower micellar distribution. For copolymer surfactants with equal C₈PhEO_nAc content, when the concentration of copolymer solution is the same, the copolymer with longer EO length forms smaller micelles. Received: 2 February 2000 Accepted: 6 October 2000     

基于碳纸电极电化学快速合成聚苯胺纳米纤维

利用碳纸电极,采用循环伏安法、恒电流法和恒电位法等电化学聚合法快速合成了高氯酸掺杂聚苯胺纳米纤维.利用电子显微镜、红外光谱和四探针测定仪等对聚苯胺的微观形貌结构、掺杂度和电导率进行了研究.用循环伏安法对聚苯胺的电化学特征进行了分析.研究发现,3种方法合成的聚苯胺均为纳米纤维状结构,长度达3μm,直径为50~150 nm.其中,循环伏安法合成的聚苯胺纳米纤维的均一性和电导率均优于其它2种方法,其电导率高达5.97 S/cm.另外,聚苯胺合成速率顺序为恒电流法>循环伏安法>恒电位法,且恒电流法合成的聚苯胺纳米纤维电极材料的放电比容量最大(578 F/g),电容性能最好.     

Recent advances in particle-based simulation of surfactants

We review the recent literature on particle-based simulation of surfactants, focusing on key methodological developments in the areas of surfactant self-assembly, micelle formation, micelle kinetics, the properties of worm-like micelles, interfacial adsorption and surface tension. We pay particular attention to dissipative particle dynamics where a considerable amount of work has been performed recently to improve parametrisation and apply the method quantitatively to surfactant systems. We discuss highlights and outstanding challenges and make suggestions for priority areas for future research directions.     

Nucleation and Growth Mechanism of Electropolymerization of Methylene Blue: The Effect of Preparation Potential on Poly(methylene blue) Structure

Nucleation and growth mechanism of electropolymerization of methylene blue (MB) in a basic medium and the effect of preparation potential on poly(MB) film structure were investigated by using cyclic voltammetry, potentiostatic current‐time transient, scanning tunneling microscopy (STM), atomic force microscopy (AFM), and UV‐vis. absorption spectroscopy techniques. Electropolymerization of MB has been achieved by potentiodynamic (cyclic voltammetry) and potentiostatic (constant potential) techniques. The potentiostatic current‐time transients fitted with a theoretical model and morphological studies indicate that nucleation and growth mechanism of poly(MB) starts with a progressive layer‐by‐layer nucleation and growth besides random adsorption. Nucleation and growth of poly(MB) follows a process between progressive layer‐by‐layer and 3‐D instantaneous mechanism resulting in highly‐oriented poly(MB) nanofibers with increasing poly(MB) film thickness. Cyclic voltammetry and morphological studies exhibit that poly(MB) film structure changes depending on the preparation potential. Poly(MB) films prepared at the potential values of 900 and 950 mV show a well‐ordered, smooth surface but at the potential values higher than 1000 mV, rough polymer surface arises as overoxidation takes place. UV‐vis. absorption spectra of poly(MB) film and MB monomer show three peaks. The peak at 410 nm for poly(MB) shows 100 nm blue shift when compared to the MB monomer and is attributed to poly(MB) formation on the electrode.