UNS: Exploiting novel surface rheology to probe and tailor 2D suspension dynamics

这项拟议的研究的目标是发现和理解发生在粒子的二维悬浮中的现象。这些颗粒悬浮在溶液中，分散得如此之广，形成了众所周知的单层悬浮液。这是一个具有工业和生物影响的非常基本的问题，因为这种悬浮液在工业和自然界中都很常见，包括乳剂和泡沫、细胞、细胞器和生物液体。该建议的重点是了解嵌入不溶性表面活性剂单分子层中的颗粒分散体的流变行为。对模型二维颗粒分散进行了精心构思的理论和实验研究。值得注意的是，选择2D系统是为了研究接近颗粒之间流动的润滑现象，从而揭示界面悬浮中新的行为模式，这在传统的三维悬浮中是没有类似的。换句话说，对2D系统的调查与对3D系统的调查一样，提供了丰富的探索领域和与现实世界的相关性。这项拟议的研究将涉及一系列典型问题的理论分析(如润滑流和胶体对动力学)，这些问题涉及其表面流变性随表面压力的变化而增厚、变薄或呈现相变的单层。它还将涉及使用光刻设计的颗粒和分散在表面活性剂单分子层中的结构的补充实验。将对浓缩2D悬浮液进行探索性实验研究，包括详细的颗粒动力学、有效流变学和不连续剪切增稠。计划扩大和传播研究，让城市大学管理学院的学生参与研究。此外，还计划开展活动，吸引4-6年级的学生学习机械、计算机和化学工程。

The goal of the proposed research is to discover and understand phenomena that occur in two-dimensional suspensions of particles. These are particles that are suspended in solutions that are so spread-out that they form what are known as monolayer suspensions. This is a very fundamental problem with industrial and biological implications, since such suspensions are very common in both industry and nature, including emulsions and foams, cells, organelles and biological fluids. The proposal is focused on the understanding of the rheological behavior of particulate dispersions embedded in insoluble monolayers of surfactants. Carefully conceived theoretical and experimental studies of model two-dimensional particulate dispersions are proposed. It is very important to note that the choice of a 2D system was made so that study of the lubrication phenomena in flows between approaching particles can reveal new modes of behavior in interfacial suspensions that have no analog in conventional three dimensional suspensions. In other words, this is a case where the investigation of a 2D system offers as rich a field of exploration and relevance to the real world as the investigation of 3D systems. The proposed research will involve theoretical analysis of a series of paradigmatic problems (e.g. lubrication flows and colloidal pair dynamics) involving monolayers whose surface rheology thickens, thins, or exhibits phase transitions as a function of surface pressure. It will also involve complementary experiments using photolithographically-designed particles and structures dispersed within surfactant monolayer. Exploratory experimental studies of concentrated 2D suspensions, including detailed particle dynamics, effective rheology, and discontinuous shear thickening will be conducted. Outreach and dissemination of research is planned, involving URM students in research. In addition, there are activities planned to reach out to 4th-6th grade students and attract them to mechanical, computer, and chemical engineering.