Growth and Flexibility of Equilibrium Polyelectrolytes

在这个由化学部实验物理化学计划支持的项目中，Magid将使用光散射和小角中子散射(SANS)来研究聚电解质以及表面活性剂在水溶液中自组装的巨大胶束的形成。在选定的情况下，胶束溶液将在类似于某些使用这些溶液的应用中发现的流场中进行研究。自组织聚电解质和共价聚电解质都将被研究，在通常被认为是两个不同研究领域之间提供了一座有价值的桥梁。本文提出的SANS实验将提供作为聚电解质链固有刚性函数的链构象的数据。特别值得注意的是，随着表面活性剂浓度的变化，胶束长度和空间组织(构象)发生了变化。这项工作将首次提供关于稀溶液中胶束生长参数的浓度依赖关系的定量数据。胶束和聚电解质广泛存在于生物体系中，它们具有各种结构和功能作用。它们也普遍存在于消费和工业应用中，如个人护理产品、药物输送系统、食品和聚合物加工中的粘度改进剂、热交换器流体中的减阻和剪切变稀、涂料以及材料的表面改性。最近的几个理论进展表明需要新的实验数据，如Magid将在她的线状胶束和聚电解质对它们的影响的研究中收集。

In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Magid will use light scattering and small-angle neutron scattering (SANS) to investigate polyelectrolytes and the formation of giant micelles that are self-assembled in aqueous solutions from surfactants. In selected cases the micellar solutions will be studied in flow fields similar to those found in some of the applications for which these solutions are used. Both self-organizing and covalent polyelectrolytes are to be studied, providing a valuable bridge between what are often considered two different fields of study. The SANS experiments proposed here will provide data on chain conformations as a function of intrinsic stiffness of the polyelectrolyte chains. Of special interest are the changes in micellar length and in spatial organization (conformation) that occur with changes in surfactant concentration. This work will produce the first quantitative numbers concerning the concentration dependence of micellar growth parameters in dilute solutions. Micelles and polyelectrolytes are broadly found in biological systems, where they have a variety of structural and functional roles. They are also ubiquitous in consumer and industrial applications such as personal-care products, drug-delivery systems, viscosity modifiers in foods and in processing of polymers, drag reduction and shear-thinning in heat-exchanger fluids, paints, and surface modification of materials. Several recent theoretical advances have pointed to the need for new experimental data such as Magid will gather in her studies of thread-like micelles and the influence of polyelectrolytes on them.