CAREER: Dynamics of Confined Colloidal Suspensions

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AbstractCTS-0348175J. Blawzdziewicz, Yale UniversityThe central goal of my career-development plan is to establish a strong complex-fluids research program focused on macroscopic and particle-scale dynamical phenomena. Due to its technological importance (discussed below) and development of new experimental techniques (optical tweezers, scanning confocal microscopy) the dynamics of complex fluids is a rapidly growing field. The research conducted in my group will be primarily theoretical and computational. However, I plan to have close collaborations with experimental groups; two such collaborations have already been established for some of my projects. My research program is well integrated with the overall needs of the Yale Mechanical Engineering Department which aims at expanding its program in colloids and complex fluids. Broader Impact The objective of my research project is to provide fundamental understanding of the dynamics of colloidal suspensions in confined geometries. This project provides a basis for advanced technological applications of colloidal systems, e.g., using colloidal crystals to producephotonic frequency-gap materials, designing new particle-fractionation methods for microfluidic devices, and development of efficient micro-filtration techniques. My career-development plan has also a significant educational component. Through research in my group and the courses I will teach, my graduate and undergraduate students will learn about physical phenomena that are crucial in emerging technologies. I also plan to reach high-school students through a series of lectures in a Frontiers of Science and Technology program at Yale.Intellectual Merit My goal is to describe the role of hydrodynamic interactions and structural forces in colloidal suspensions bounded by confining walls or fluid interfaces. The interplay of the hydrodynamic and structural phenomena (e.g., particle ordering) is particularly pronounced when the smallest dimension associated with the confinement geometry (e.g., film thickness) is comparable to the particle size. I propose investigations of nonequilibrium hydrodynamic and structural confinement effects in the following colloidal systems:Particles adsorbed at a fluid interface Such particles are often used to stabilize or destabilize emulsions and foams. Our aim is to provide a macroscopic description for the dynamics of a monolayer of adsorbed particles and to evaluate the corresponding macroscopic transport coefficients in terms of the structural evolution on the particle scale.Particle-stabilized thin liquid films Our goal is to develop a nonequilibrium-thermodynamicsformalism for description of the process of the stepwise thinning of such films. The microscopic mechanisms of the effective thermodynamic forces and the corresponding transport phenomena will be investigated, and quantitative results for the transport coefficients will be obtained.Colloidal suspensions in slit pores We will study the dynamics of colloidal particles confined in pores and microfluidic channels of the width comparable to the particle diameter. We will explore the coupling of the microscopic suspension structure with the macroscopic lateral motion. A theory for suspension dynamics in pores with varying width will be developed.Particle deposition on a planar wall We will investigate the effect of many-particle hydrodynamic interactions on the structure of colloidal crystals produced by particle deposition on uniform and chemically patterned walls. The removal of adsorbed particles from a surface by an applied flow will also be studied.My project involves numerical and theoretical components. To perform the proposed numerical investigations we will develop fast Stokesian-dynamics algorithms for colloidal suspensions confined in spaces bounded by planar or nearly-planar surfaces. The applicability of our proposed theoretical and numerical methods will go beyond the research problems outlined above. In future studies we will use these methods to study interactions between particle clusters, filtration processes, thermocapillary phenomena, and bacterial motions. The proposed project will also provide a preliminary basis for launching a new research program for molecular fluids adsorbed in micropores.