Adsorption of Surfactant Mixtures at Solid-Liquid Interfaces: A Study of Interactions and Dynamics Using Spectroscopic, Electrokinetic, and Calorimetric Techniques

小行星9622781 表面活性剂可用于几种商业方法，但制备异构体纯表面活性剂的固有困难和过高的成本使得必须使用表面活性剂混合物。 此外，表面活性剂的混合物的性能远远上级单个组分的性能，这导致在许多产品如洗涤剂和化妆品中故意添加表面活性剂混合物。 表面活性剂在大多数应用中的有效性取决于吸附（或缺乏吸附）以及吸附层的微观结构。 已经做了大量的工作来了解在确定表面活性剂的吸附所涉及的机制，但很少有表面活性剂的混合物。 成功设计试剂组合的关键取决于对溶液中和固液界面处形成的表面活性剂结构的微观和纳米结构特征的理解，以及基于单个组分的性质的预测模型的开发。 这是拟议的研究的目标，调查不同特性的表面活性剂和混合吸附层的微观和纳米结构之间的相互作用，使用多管齐下的方法，结合经典的吸附工具，电动力学，润湿性和微量热与现代光谱技术，如荧光，电子自旋共振（ESR），光漂白后的荧光恢复（FRAP），和二次谐波产生（SHG）。 荧光和ESR光谱将用于确定吸附层的微极性、微粘度和聚集数; FRAP用于探测所涉及的动力学; SHG用于探测界面处分子的相对和绝对取向。 pH值，表面活性剂的结构，盐度，温度和这些参数的扰动的影响将被确定，以帮助阐明吸附机制和相关的动力学。 除了直链烷基芳基磺酸盐和二甲苯磺酸盐等表面活性剂外，新型糖基环境友好型表面活性剂将是研究的重点。 预计多管齐下的实验和理论方法，已成功地用于单一的表面活性剂将有助于开发预测有用的模型，表面活性剂混合物在固体上的吸附。 ***

9622781 Somasundaran Surfactants find use in several commercial processes but the inherent difficulty and excessive costs involved in preparing isomerically pure surfactants has necessitated the utilization of surfactant mixtures. Moreover, the performance of mixtures of surfactants is far superior to that of the individual components which has resulted in the deliberate addition of surfactant mixtures in many products such as detergents and cosmetics. The effectiveness of the surfactant in a majority of the application s depends upon the adsorption (or lack of it) as well as the microstructure of the adsorbed layers. Much work has been done to understand the mechanisms involved in determining adsorption of surfactants but very little of it has been with mixtures of surfactants. The key to the successful design of reagent combinations depends upon the understanding of the micro and nanostructural features of surfactant structures formed in solution and at solid-liquid interfaces coupled with the development of predictive models based upon the properties of individual components. It is the goal of the proposed research to investigate the interactions between surfactants of different characteristics and the micro and nanostructures of the mixed adsorbed layers using a multi-pronged approach combining classical tools of adsorption, electrokinetics, wettability and microcalorimetry with modern spectroscopic techniques such fluorescence, electron spin resonance (ESR), fluorescence recovery after photobleaching (FRAP), and second harmonic generation (SHG). Fluorescence and ESR spectroscopy will be used to determine the micropolarity, the microviscosity and aggregation numbers of the adsorbed layers; FRAP to probe the dynamics involved; SHG to probe the relative and absolute orientation of the molecules at the interface. Effects of pH, surfactant structure, salinity, temperature and perturbations in these parameters will be determined to assist in elucidating the adsorption mechanisms and associated dynamics. In addition to the surfactants such as linear alkyl aryl and xylene sulfonates, novel sugar based environmentally friendly surfactants will be a focus of the study. It is expected that the multi-pronged experimental and theoretical approach that has been successfully used for single surfactants will help in developing predictive useful models for adsorption of surfactant mixtures on solids. ***