Microscale Flows to Engineer Fluid Interfaces Containing Macromolecular and Colloidal Species

这项拟议工作的目标是开发控制流动(流动)界面上吸附物种存在的实验方法。这项工作是在一个简化的理论模型的框架下进行的，该模型是为表面活性剂存在下的界面破裂而开发的。这项工作的智力价值在于开发了解决涉及表面活性剂动力学和流体流动耦合问题的工具。我们将通过对一个具体的例子进行详细的实验分析和建模来开发这些工具：表面活性剂介导的用于形成亚微米液滴的倾斜流。这些研究将有助于阐明控制更广泛的界面流动应用的关键机制，从而实现对关键过程的更好控制。这个框架将使移动界面的工程成为可能，我们将利用这一能力开发新的方法来量化更复杂的分子(即生物分子、大分子和胶体)的广告/解吸动力学，并解决一个特定的应用，即量化蛋白质在界面上的变性动力学。这项工作的结果将产生广泛的技术影响，因为表面活性剂多相流在乳化、喷涂和涂层等技术中以及在新材料的喷墨打印或微流控设备中的两相流等新兴应用中具有重要意义，这些应用已被用于合成单分散液滴、气泡、胶体颗粒和其他新型胶体组件。以这项工作为特征的界面和微流体流动将产生广泛的教育影响，通过提供高度可视化的图像和流体动力学示例，可以为两个PI的主要外展、本科研究和课程开发活动提供支持。

The goal of the proposed work is to develop experimental methods for controlling the presence of adsorbed species at mobile (flowing) interfaces. This work is guided by the framework of a simplified theoretical model that has been developed for interface breakup in the presence of surfactants. The intellectual merit of this work is the development of tools to tackle problems involving coupled surfactant dynamics and fluid flow. We will develop these tools through detailed experimental analysis and modeling of a specific example: surfactant-mediated tipstreaming for formation of submicron droplets. These studies will help elucidate the critical mechanisms controlling a broader set of interfacial flow applications, enabling greater control over key processes. This framework will enable the engineering of mobile interfaces, and we will use this capability to develop novel methods for quantifying the kinetics of ad/desorption of more complex molecules (i.e, biomolecules, macromolecules and colloids) and tackle a specific application, quantification of the kinetics of denaturation of proteins at interfaces. The results of this work will have broad technological impact because of the importance of surfactant-laden multiphase flows in technologies such as emulsification, spraying and coatings and in emerging applications such as ink-jet printing of new materials or two-phase flows in microfluidic devices, which have been exploited to synthesize monodisperse droplets, bubbles, colloidal particles, and other novel colloidal assemblies. The interfacial and microfluidic flows characterized by this work will have broad educational impact by providing highly visual images and fluid dynamics examples that can feed into the major outreach, undergraduate research, and course development activities of the two PIs.