多糖类大分子与表面活性剂相互作用的研究进展

多糖类大分子具有天然、无毒、使用安全和可再生及来源丰富等优点. 将多糖类大分子与表面活性剂复配使用, 不仅可利用各自的优势和特性, 而且能发挥二者的协同作用, 大大改善二者的性能. 由于两者之间存在诸如静电作用、疏水作用、偶极相互作用、氢键作用、空间位阻效应等, 水体系中表面活性剂在多糖分子链上的缔合得到调控, 并引起表面活性剂的临界聚集浓度(cac)、临界胶束浓度(cmc)、结合量, 以及体系的表面吸附、界面流变性等呈现各种变化. 本文简要总结了近年来多糖类大分子与表面活性剂复配体系研究方面取得的一些进展, 述及复配体系研究中所采用的方法与手段, 主要讨论复配体系的物理化学性质以及多糖类大分子与表面活性剂相互作用的机制.     

表面活性剂对硫醇单层膜修饰金电极电化学行为的影响

利用自组装方法在金电极表面制备成硫醇单层膜, 循环伏安和交流阻抗实验表明硫醇单层膜与表面活性剂十六烷基三甲基溴化胺作用后, 其电化学行为发生变化, 对于带有不同电荷的探针分子, 表现出一定的选择性响应. 即使是带有相同电荷的探针分子, 由于与表面活性剂的作用方式不同, 也使它们通过硫醇单层膜在电极表面产生电化学响应的程度完全不同.     

表面活性剂在水溶液中性质的质子核磁共振研究

综述了质子核磁共振的几种方法在表面活性剂水溶液研究中的应用.自从上世纪六十年代以来的许多研究表明核磁共振的各种技术是研究表面活性剂溶液的有效手段.它可以提供表面活性剂在水溶液中的cmc、胶束的结构、尺寸、水化、加溶性质和位置，不同表面活性剂胶束之间的相互作用，以及胶束与生物分子和高聚物的相互作用.化学位移已经成为惯常方法，弛豫测量提供动态信息，自扩散系数测量是研究胶束尺寸的很好手段.近来由于核磁共振技术的不断发展，用于研究生物大分子的2D NOESY和HOESY也逐渐应用到研究表面活性剂聚集结构中.由此可以得到有关表面活性剂在水溶液中行为的分子水平信息，是其它谱学方法所不能及的.     

用离子选择性电极测定阴离子表面活性剂的临界胶束浓度

临界胶束浓度(简称C.M.C.)是表面活性剂的特性参量,与表面活性剂的分子结构、电解质浓度有关。测定C.M.C.的常用方法有电导法、表面张力法、光散射法、渗透系数法等。Birch和 Newbery等曾用十二烷基硫酸根离子选择性电极测定该离子的C.M.C。本文以三庚基十二烷基铵和十二烷基苯磺酸生成的离子对缔合物为电极活性物,根据其所试制的液膜型或 PVC膜型阴离子洗涤剂选择性电极(简     

聚氧乙烯基醚非离子表面活性剂选择电极的制备和应用

最近Jones等曾报导聚氧乙烯基醚非离子表面活性剂作为钡离子的络合剂所制备的选择性电极,对非离子表面活性剂具有响应,并用标准加入法测定了合成洗涤剂中的非离子表面活性剂。本文采用钡离子-聚氧乙烯壬基苯醚-四苯硼酸根生成的络合物为电极活性物,制备了PVC膜非离子表面活性剂选择电极,研究了它对Ba~(2+)、四苯硼酸根(TPB~-)、聚氧乙烯     

Gemini表面活性剂对疏水缔合聚丙烯酰胺界面吸附膜扩张流变性质的影响

采用小幅低频振荡和界面张力弛豫技术, 考察了疏水缔合水溶性聚丙烯酰胺(HMPAM)在正癸烷-水界面上的扩张黏弹性质, 研究了不对称Gemini表面活性剂C₁₂COONa-p-C₉SO₃Na对其界面扩张性质的影响. 研究发现, 疏水链段的存在, 使HMPAM在界面层中具有较快的弛豫过程, 扩张弹性显示出明显的频率依赖性. 表面活性剂分子可以通过疏水相互作用与聚合物的疏水嵌段在界面上形成类似于混合胶束的特殊聚集体. 表面活性剂分子与界面聚集体之间存在快速交换过程, 可以大大降低聚合物的扩张弹性. 同时, 聚合物分子链能够削弱表面活性剂分子长烷基链之间的强相互作用, 导致混合吸附膜的扩张弹性远低于单独表面活性剂吸附膜.     

界面扩张流变方法研究大分子与表面活性剂的相互作用

结合本课题组的工作, 较系统地总结了近年来有关界面扩张流变技术在大分子/表面活性剂混合体系研究中的应用. 大量研究表明, 通过分析界面扩张粘弹性数据和界面弛豫过程的特征参数可以研究界面层微观性质, 从而阐明大分子/表面活性剂的相互作用机理, 这对实际生产和应用具有重要的指导意义.     

稳态荧光法研究表面活性剂/大分子相互作用

稳态荧光技术已被证明是研究表面活性剂缔合体系的重要手段, 它对水介质体系中发生的相变具有十分灵敏的检测能力. 结合本课题组的工作, 系统地总结了利用荧光光谱技术研究表面活性剂与大分子相互作用的方法和原理.     

树枝状大分子与表面活性剂相互作用的研究进展

聚酰胺-胺(PAMAM)是目前最具应用前景的树枝状大分子(Dendrimer),它与表面活性剂相互作用后能够形成聚集体,这种聚集体能有效地改变体系的微观环境和物理化学性质。本文综述了小分子表面活性剂与Dendrimer相互作用研究方面所取得的进展,重点讨论了阴离子表面活性剂和阳离子表面活性剂与Dendrimer混合体系中溶液的疏水环境、浊度以及形成的聚集体的中值粒径等物理化学性质的变化,在此基础上,讨论了Dendrimer与小分子表面活性剂相互作用机理研究所取得的进展,为进一步扩大Dendrimer的应用领域提供参考。     

电位控制ZnO/表面活性剂复合多层膜在固/液界面上的自组装

通过控制固/液界面电极电位的方式, 控制表面活性剂和金属离子在电极表面的自组装, 制备出了高度取向的ZnO/表面活性剂复合多层膜. 对无机层形态和结构进行了分析, 并采用X射线反射率和X射线漫散射研究了电极电位控制下ZnO/表面活性剂复合多层膜在固/液界面的自组装生长. 结果表明, 在一定电位下, 只有当表面活性剂浓度低于其饱和吸附浓度时, 采用阶跃电位沉积方式才能明显改变复合薄膜的周期厚度; 恒电位沉积方式控制电极电位时, 随着沉积电位的提高, 多层膜层状结构由一组层状相变为多组层状相, 同时层状结构的取向变差. 实验研究结果验证了电化学自组装过程是由金属离子的还原速度和表面活性剂的吸附速度二者共同控制完成的.     

Microcalorimetric evidence of hydrophobic interactions between hydrophobically modified cationic polysaccharides and surfactants of the same charge

We synthesized and characterized a series of new polymers-hydrophobically modified cationic polysaccharides-based on dextran having pendant N-(2-hydroxypropyl)-N,N-dimethyl-N-alkylammonium chloride groups randomly distributed along the polymer backbone. These polymers are good candidates for studying the hydrophobic effect on polymer/surfactant association. In previous papers we reported their interactions with oppositely charged surfactants. For further insight into the relative importance of the hydrophobic interaction in the association process now we studied the thermodynamics of the interaction of these hydrophobically modified polymers with surfactants of the same charge (DMRX/CnTAC) by isothermal titration calorimetry (ITC). In order to try to discriminate the solution behavior of these polymer/surfactant systems, we analyzed separately the interaction of unmodified dextran with ionic surfactants and the interactions between the corresponding cationic surfactants. The interaction enthalpies for DMRX/CnTAC systems were derived from a proposed thermodynamic model with equations that describe the polymer-surfactant interactions. The thermodynamic parameters for the DMRX/CnTAC aggregation process as well as surfactant micellization in the presence of the polymer were also calculated. From all the results we were able to ascertain the effect on the interactions of changing the alkyl chain length of the polyelectrolyte pendant groups or the surfactant. The importance of the polymer aggregation state on the mechanism of interaction was also addressed.     

Polymer/surfactant interactions at the air/water interface

The development of neutron reflectometry has transformed the study and understanding of polymer/surfactant mixtures at the air/water interface. A critical assessment of the results from this technique is made by comparing them with the information available from other techniques used to investigate adsorption at this interface. In the last few years, detailed information about the structure and composition of adsorbed layers has been obtained for a wide range of polymer/surfactant mixtures, including neutral polymers and synthetic and naturally occurring polyelectrolytes, with single surfactants or mixtures of surfactants. The use of neutron reflectometry together with surface tensiometry, has allowed the surface behaviour of these mixtures to be related directly to the bulk phase behaviour. We review the broad range of systems that have been studied, from neutral polymers with ionic surfactants to oppositely charged polyelectrolyte/ionic surfactant mixtures. A particular emphasis is placed upon the rich pattern of adsorption behaviour that is seen in oppositely charged polyelectrolyte/surfactant mixtures, much of which had not been reported previously. The strong surface interactions resulting from the electrostatic attractions in these systems have a very pronounced effect on both the surface tension behaviour and on adsorbed layers consisting of polymer/surfactant complexes, often giving rise to significant surface ordering.     

The interaction of mixed surfactants with polyelectrolytes

The interactions between a linear polymer, sodium poly(2-acrylamide-2-methylpropane sulfonate), and two cationic surfactants, dodecylpyridinium chloride and tetradecylpyridinium chloride and their mixtures with different ratios, were studied by a potentiometric titration method using a surfactant-selective electrode. The ideal mixing/ideal cooperative binding model we had proposed previously was applied to successfully predict the binding isotherms of the mixed surfactant systems and the critical aggregation concentrations of the binding. The binding of surfactant mixtures to polymers is similar to the ideal mixed micelle formation and a sort of synergetic effect was found during the binding process. Received: 18 August 1998 Accepted in revised form: 6 November 1998     

On the influence of surfactants on the adsorption of polysaccharide-based polymers on cotton studied by means of fluorescence spectroscopy

In this study, we examined the influence of surfactants on the adsorption of polymers on cotton fibers. The extent of polymer adsorption on cotton was determined directly by means of fluorescence spectroscopy using fluorescently labeled polymers. The investigation of polymer adsorption in the presence of different types of surfactants and for a large range of differently structured polymers allows us to obtain a rather general picture of this important issue. Systematic relationships between the presence of surfactant and the type of polymer can be deduced but cannot be cast in simple terms such as electrostatic interaction but instead depend on the detailed interaction between the surfactant and polymer both in solution and adsorbed on the cotton surface. A particularly complex situation arises for the case of oppositely charged surfactant and polymer because of the possibility of precipitate formation. The study of such complex systems not only is of scientific interest but also is of great commercial interest because both polymers and surfactants are parts of detergent formulations and cotton is one of the most abundantly used materials for fabrics.     

Interaction between the water soluble poly{1,4-phenylene-[9,9-bis(4-phenoxy butylsulfonate)]fluorene-2,7-diyl} copolymer and ionic surfactants followed by spectroscopic and conductivity measurements

The interaction has been studied in aqueous solutions between a negatively charged conjugated polyelectrolyte poly{1,4-phenylene-[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer (PBS-PFP) and several cationic tetraalkylammonium surfactants with different structures (alkyl chain length, counterion, or double alkyl chain), with tetramethylammonium cations and with the anionic surfactant sodium dodecyl sulfate (SDS) by electronic absorption and emission spectroscopy and by conductivity measurements. The results are compared with those previously obtained on the interaction of the same polymer with the nonionic surfactant C12E5. The nature of the electrostatic or hydrophobic polymer-surfactant interactions leads to very different behavior. The polymer induces the aggregation with the cationic surfactants at concentrations well below the critical micelle concentration, while this is inhibited with the anionic SDS, as demonstrated from conductivity measurements. The interaction with cationic surfactants only shows a small dependence on alkyl chain length or counterion and is suggested to be dominated by electrostatic interactions. In contrast to previous studies with the nonionic C12E5, both the cationic and the anionic surfactants quench the PBS-PFP emission intensity, leading also to a decrease in the polymer emission lifetime. However, the interaction with these cationic surfactants leads to the appearance of a new emission band (approximately 525 nm), which may be due to energy hopping to defect sites due to the increase of PBS-PFP interchain interaction favored by charge neutralization of the anionic polymer by cationic surfactant and by hydrophobic interactions involving the surfactant alkyl chains, since the same green band is not observed by adding either tetramethylammonium hydroxide or chloride. This effect suggests that the cationic surfactants are changing the nature of PBS-PFP aggregates. The nature of the polymer and surfactant interactions can, thus, be used to control the spectroscopic and conductivity properties of the polymer, which may have implications in its applications.     

Surfactant effect on the lower critical solution temperature of poly(organophosphazenes) with methoxy-poly(ethylene glycol) and amino acid esters as side groups

 The surfactant effect on the lower critical solution temperature (LCST) of thermosensitive poly(organophosphazenes) with methoxy-poly(ethylene glycol) and amino acid esters as side groups was examined in terms of molecular interactions between the polyphosphazenes and surfactants including various anionic, cationic, and nonionic surfactants in aqueous solution. Most of the anionic and cationic surfactants increased the LCST of the polymers: the LCST increased more sharply with increasing length and hydrophobicity of the hydrophobic part of the surfactant molecule. The ΔLCSTs (T _0.03M− T _0M), the change in the LCST by addition of 0 and 0.03 M sodium dodecyl sulfate (SDS), were found to be 7.0 and 14.5 °C for the polymers bearing ethyl esters of glycine and aspartic acid, respectively. The LCST increase of poly(organophosphazene) having a more hydrophobic aspartic acid ethyl ester was 2 times larger compared with that of the polymer having glycine ethyl ester as a side group. The binding behavior of SDS to the polymer bearing glycine ethyl ester as a hydrophobic group was explained from the results of titration of the polymer solutions containing SDS with tetrapropylammonium bromide. Graphic models for the molecular interactions of polymer/surfactant and polymer/surfactant/salt in aqueous solutions were proposed. Received: 17 February 2000/Accepted: 25 April 2000     

Foaming and foam stability for mixed polymer-surfactant solutions: effects of surfactant type and polymer charge

Solutions of surfactant-polymer mixtures often exhibit different foaming properties, compared to the solutions of the individual components, due to the strong tendency for formation of polymer-surfactant complexes in the bulk and on the surface of the mixed solutions. A generally shared view in the literature is that electrostatic interactions govern the formation of these complexes, for example between anionic surfactants and cationic polymers. In this study we combine foam tests with model experiments to evaluate and explain the effect of several polymer-surfactant mixtures on the foaminess and foam stability of the respective solutions. Anionic, cationic, and nonionic surfactants (SDS, C(12)TAB, and C(12)EO(23)) were studied to clarify the role of surfactant charge. Highly hydrophilic cationic and nonionic polymers (polyvinylamine and polyvinylformamide, respectivey) were chosen to eliminate the (more trivial) effect of direct hydrophobic interactions between the surfactant tails and the hydrophobic regions on the polymer chains. Our experiments showed clearly that the presence of opposite charges is not a necessary condition for boosting the foaminess and foam stability in the surfactant-polymer mixtures studied. Clear foam boosting (synergistic) effects were observed in the mixtures of cationic surfactant and cationic polymer, cationic surfactant and nonionic polymer, and anionic surfactant and nonionic polymer. The mixtures of anionic surfactant and cationic polymer showed improved foam stability, however, the foaminess was strongly reduced, as compared to the surfactant solutions without polymer. No significant synergistic or antagonistic effects were observed for the mixture of nonionic surfactant (with low critical micelle concentration) and nonionic polymer. The results from the model experiments allowed us to explain the observed trends by the different adsorption dynamics and complex formation pattern in the systems studied.     

Effects of surfactant micelles on viscosity and conductivity of poly(ethylene glycol) solutions

The neutral polymer-micelle interaction is investigated for various surfactants by viscometry and electrical conductometry. In order to exclude the well-known necklace scenario, we consider aqueous solutions of low molecular weight poly(ethylene glycol) (2-20)x10(3), whose radial size is comparable to or smaller than micelles. The single-tail surfactants consist of anionic, cationic, and nonionic head groups. It is found that the viscosity of the polymer solution may be increased several times by micelles if weak attraction between a polymer segment and a surfactant exists, epsilon相似文献   

Fluorometric and isothermal titration calorimetric studies on binding interaction of a telechelic polymer with sodium alkyl sulfates of varying chain length

Steady-state fluorescence measurements and isothermal titration calorimetric experiments have been performed to study the interaction between a telechelic polymer, pyrene-end-capped poly(ethylene oxide) (PYPY), and sodium alkyl sulfate surfactants having decyl, dodecyl, and tetradecyl hydrocarbon tails. Fluorometric results suggest polymer-surfactant interaction in the very low range of polymer concentrations. The relative variation in the excimer to monomer pyrene emission intensities with varying surfactant concentration reveals that initial addition of surfactant favors intramolecular preassociation until the surfactant molecules start binding with the ethylene oxide (EO) chain. With the growing number of surfactant aggregates along the EO chain, the association becomes hindered due to the polyelectrolyte effect. The results from microcalorimetric titrations in the low concentration range of PYPY solution (approximately 10(-6) M) with alkyl sulfates suggest two kinds of surfactant-polymer interactions, one with the polymer hydrophobic end groups and the other with the ethylene oxide backbone. The overall polymer-surfactant interaction starts at a much lower surfactant concentration for the hydrophobically modified polymers compared to that in the case of unsubstituted poly(ethylene oxide) homopolymer. From the experiments critical aggregation concentration values and the second critical concentration where free micelles start forming have been determined. An endeavor has been made to unveil the mechanism underlying the corresponding associations of the surfactants with the polymer.     

Polyelectrolyte and surfactant mixed solutions. Behavior at surfaces and in thin films

Dilute mixed solutions of non-surface active anionic polymers (polyacrylamide and polystyrene sulfonate, xanthan) and various surfactants have been studied with several methods: surface tension, ellipsometry, X-ray and neutron reflectivity, thin film balance, surface and bulk rheology. A strong synergistic lowering of the surface tension is found with cationic surfactants in the concentration range where no appreciable complexation of surfactant and polymer occurs in the bulk solution (as seen from viscosity measurements). Despite appreciable differences between surface tension behaviour, the adsorbed layer is very similar for all the polymers: their thickness is small and the polymer chains are stretched along the surface. The surface tension behaviour of these polymers with non-ionic surfactants is also different. When the polymers are confined in thin films, the forces between surfaces are similar, and independent of surfactant nature: oscillatory forces are measured, which reflect the existence of a polymer network with a well defined mesh size. The connection of foam stability with surface and bulk complexation is far from clear.