Dynamic Aggregation Behavior of Surfactant Mixtures in Solutions and at Solid/liquid Interfaces

哥伦比亚大学拟议研究的目标是研究混合体系中表面活性物质聚集体的形成，特别是所涉及的动力学。由于实验系统复杂，该战略涉及使用多管齐下的方法，将超滤、分析、离心机、微量热法和原子力显微镜等技术与先进的光谱技术相结合，包括表面等离子体共振光谱、荧光和电子自旋共振。其目的是确定由混合胶束和半胶束的形状、组成和结构决定的表面活性剂的结构与其性能之间的关系。基于这些结果，将改进一个最近的理论模型，以能够预测表面活性剂在其混合物中形成的聚集体和它们的变化。本提案中研究的表面活性剂将包括环境友好的糖基和吡咯烷酮类表面活性剂。研究人员已经看到，这些表面活性剂在固体上的吸附确实表现出不同寻常的选择性，但选择性的原因尚不清楚。同样，另一个重要的例子是在浮选中观察到的硫醇表面活性剂之间的协同作用，这一点还没有被很好地理解。对它们的协同作用的研究将是我们和南非开普敦大学小组的合作努力，该小组一直从热力学的角度研究这个问题。拟议的研究将使研究人员能够通过获取关于表面活性剂在其混合物中形成聚集体的新信息来推进表面活性剂胶体化学的前沿。这些信息将使人们有可能开发机会，充分利用混合表面活性剂聚集体提供的独特纳米环境，用于粒子加工、超提纯、纳米域中的反应以及从这些域控制释放。

ABSTRACTCTS-0089530Columbia UniversityThe goal of the proposed research is to investigate the formation of surfactant aggregates in mixed systems and particularly the dynamics involved. As the experimental system is complex the strategy involves use of multi-pronged approach, combining several techniques such as ultra-filtration, analytical, centrifuge, micro-calorimetry and AFM, with advanced spectroscopic techniques including Surface Plasmon Resonance Spectroscopy, fluorescence and ESR. The goal is to determine the relationship between structures of surfactants and their properties as determined by the shape, composition and structure of mixed micelles and hemimicelles. Based on these results a recent theoretical model will be refined to enable prediction of the formation of surfactant aggregates in their mixtures and changes in them.Surfactants to be studied in this proposal will include environmentally benign sugar-based and pyrrolidone-type surfactants. The investigators have seen that these surfactants do show unusual selectivity in their adsorption on solids, but the reasons for the selectivity are not known. Similarly, another important example is the synergy observed between the thiol surfactants in flotation, which is not well understood. Study of their synergy will be a collaborative effort between us and the University of Cape Town, South Africa group which has been studying the issue from a thermodynamic point of view. The proposed research will enable the investigators to advance the frontiers of surfactant colloidal chemistry by acquiring new information on the formation of surfactant aggregates in their mixtures. Such information will make it possible to develop opportunities to fully utilize the unique nano-environment provided by mixed surfactant aggregates for particle processing, ultra-purification, reactions in nano-domains as well as controlled release from such domains.