CAREER: Direct visualization of the structure and dynamics of complex fluids during flow by confocal and epifluorescence microscopy

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AbstractCTS-0093076M. Solomon, University of MichiganStudies of the structure and dynamics of complex fluids, particularly in the presence of flow, address fundamental questions of engineering science in fluid physics, rheology and colloidal science. Direct visualization techniques of confocal laser scanning microscopy and epifluorescence microscopy promises new development in these areas by capturing actual pictures of colloidal particle positions and displacements in three and two dimensions, respectively. We propose an integrated program of research and education with the research aim of using these methods to directly observe complex fluid structure and dynamics during flow. The materials studied will be colloidal particulate gels and associative polymer solutions containing colloidal particles. The work will impact the areas of ceramics, paints, inks, digital storage media and DNA sequencing. In addition, our recent scattering and rheological studies of these materials have identified research questions in which direct visualization methods generate opportunity for unprecedented discovery.The research plan involves the use of a specially designed and constructed shear cell that will be mounted on a confocal laser scanning microscope and an epifluorescence microscope. Experiments will encompass transient and steady shear flow in both linear and non-linear regimes. Associated polymers and fluorescent colloids necessary for the work will be synthesized in house by previously tested methods. Training for two graduate students, and research opportunities for a number of undergraduates, will be provided.The research efforts will also synergistically promote parallel efforts in education and outreach. An undergraduate elective in polymers will be redesigned to teach the skills necessary to manipulate polymeric complex fluids at the molecular level. A research project requiring original analysis will be instituted that will reinforce this new educational material. A graduate course in complex fluids will be incrementally revised to include new results of direct visualization methods, as they become available, thereby providing a conduit between the research program and graduate education. In an outreach project, hands-on complex fluid projects will be developed for a program in which middle school students from groups traditionally underrepresented in engineering come to the department for tutoring and instruction.