UNS: Diffusion of Strongly Interacting Species in Microemulsions and Gels

CBET-1506474 PI：Phillips，Ronald J。这个项目的目标是了解分子在两种复杂介质中的扩散-微乳液和聚合物凝胶。微乳是聚集态表面活性剂在水中的溶液，用于药物给药，以增加溶解度、降低毒性和控制药物释放速度。聚合物凝胶是由线状分子组成的充满水的网络，它们被用于凝胶色谱和膜过滤以分离分子。纤维凝胶因纤维间液体的变化而收缩或膨胀，这以一种未知的方式强烈地影响了它们的功能。研究人员将使用光学技术来测量微乳液和聚合物凝胶中的分子运动速度。数据将与理论进行比较，以改进这些复杂体系的理论模型。疏水溶质在胶束或表面活性剂聚集体存在时的扩散将被测量。在这样的体系中，聚集体内部的局域相互作用强烈影响溶质和表面活性剂的扩散速度。聚合物凝胶中也存在强烈的溶质-基质相互作用，聚合物纤维阻碍溶质运动，溶质分子可能导致凝胶膨胀或收缩。微乳液中的扩散速度和聚合物水凝胶中的收缩和膨胀将通过全息干涉测量，这是一种监测透明溶液和凝胶中浓度变化的光学方法。还将使用泰勒扩散法、固相微萃取、单光子计数荧光光谱和渗透压法来测量将这些过程的数据与理论描述进行比较所需的物理性质。

CBET - 1506474PI: Phillips, Ronald J.The goal of this project is to understand molecular diffusion in two types of complex media - microemulsions and polymer gels. Microemulsions are solutions of aggregated surfactants in water, and they are used in pharmaceutical drug delivery to increase solubility, reduce toxicity, and control the rate of drug release. Polymer gels are water-filled networks of thread-like molecules, and they are used in gel chromatography and membrane filtration to separate molecules. Fibrous gels shrink or swell in response to changes in the liquid between the fibers, which strongly affects their function in ways that are not understood. The investigators will use an optical technique to measure rates of molecular movement in microemulsions and polymer gels. Data will be compared with theory to improve theoretical models for these complex systems.The diffusion of a hydrophobic solute in the presence of micelles or surfactant aggregates will be measured. In such systems, localized interactions in the interior of the aggregates strongly affect diffusion rates of the solute and the surfactant. Strong solute-matrix interactions also occur in polymer gels, in which polymer fibers hinder solute motion, and solute molecules may induce gel swelling or shrinkage. Diffusion rates in microemulsions and shrinking and swelling in polymer hydrogels will be measured by holographic interferometry, an optical method for monitoring changes in concentration in transparent solutions and gels. Taylor diffusiometry, solid phase microextraction, single-photon counting fluorescence spectroscopy, and osmometry will also be used to measure physical properties needed to compare data to theoretical descriptions of these processes.