Adsorption of Polyelectrolytes at Charged Surfaces

本研究旨在建立聚电解质在固/液界面上吸附/脱附相变的条件。一个主要目标是提供一套全面的数据，以检验一些尚未得到充分检验的关于聚电解质吸附的广泛理论工作，并促进理论的进一步发展。在最新理论的指导下，详细考察了表面电荷、聚合物电荷、支持电解质浓度、温度和分子质量等变量对吸附转变的影响。调节表面电荷的主要手段将是通过双电层的原位恒电位控制。将小心地生产出具有明确定义的表面，以便可以自信地检验这一理论。吸附聚合物膜的厚度以及聚电解质分子的附着方式将分别用椭偏仪和表面增强拉曼散射进行检测。石英晶体微天平和红外反射等技术将被用于探测这些二维系统中的相变。使用带电和中性聚合物的竞争吸附研究将揭示库仑和非库仑表面/聚合物相互作用的相对重要性。这项研究可能会导致电子材料、生物分子材料的进步，以及用于净水的絮凝剂的改进。

This research is directed at establishing the conditions for the adsorption/desorption phase transition for polyelectrolytes at the solid/solution interface. A primary goal is to provide a comprehensive set of data to examine some of the extensive theoretical work on polyelectrolyte adsorption, which has not yet been fully tested, and to stimulate further development of theory. Guided by recent theory, the effect on the adsorption transition of variables such as the surface charge, polymer charge, supporting electrolyte concentration, temperature and molecular weight will be examined in detail. The principal means of regulating the surface charge will be through in situ potentiostatic control of the electrical double-layer. Care will be taken to produce surfaces with well-defined morphology so that the theory may be tested with confidence. The thickness of adsorbed polymer films, as well as the mode of attachment of polyelectrolyte molecules, will be examined by ellipsometry and surface enhanced Raman scattering, respectively. Novel applications of techniques such as the quartz crystal microbalance and infrared reflectance will be undertaken to probe phase transitions in these two-dimensional systems. Competitive adsorption studies using charged and neutral polymers will reveal the relative importance of coulombic and non-coulombic surface/polymer interactions. This research could potentially lead to advances in electronic materials, biomolecular materials, and improvements in flocculants for water purification.