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Prof. Sharon Gerbode - Harvey Mudd College - “Shape matters - why wavy crystal grains shrink faster”

Abstract: The growth and dissolution of individual grains within a crystalline material affects material properties ranging from conductivity to mechanical strength. In traditional metallurgy, grain evolution is successfully described by continuum theories of grain boundary motion that smooth over individual crystal defects. Yet, as technology demands ever smaller crystalline devices, the limits of such models can be called into question.

In our experimental and computational studies of hard sphere colloidal crystals, we find that, contrary to the predictions of established continuum theories, colloidal crystal grains do not shrink linearly in time. Furthermore, we find that the lifetime of a crystal grain depends on its initial shape, in disagreement with predictions based on capillary - driven grain boundary motion. These discoveries suggest that the simple curvature - based models for grain evolution that work well for macroscopic materials don't capture the behavior of small hard sphere crystal grains, hinting that a new approach might be needed to more accurately predict the evolution of small crystal grains.

Bio: Sharon Gerbode, the Iris and Howard Critchell Associate Professor of Physics at Harvey Mudd College, started as a creative writing major at UC Santa Cruz and switched to physics in her third year of college. In graduate school at Cornell University she discovered her passion for tabletop soft matter experiments, where microscope images of colloidal particles made statistical mechanics tangible. Following her postdoctoral studies of plant biomechanics at Harvard, Sharon started as a physics professor at Harvey Mudd, where she loves to work with undergraduate research students on soft matter experiments. Her work has been supported by the RCSA through a Cottrell College award and as a Cottrell Scholar.

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Prof. AJ Boydston - Univ of Wisconsin, Madison - “Diversifying the 3D Printing Ecosystem with Functional Multimaterial Capabilities”

Abstract: For this seminar, I will discuss a recent research thrust from my program: additive manufacturing (AM) with mechanoresponsive materials. Our research team focuses on discovering and developing new chemistry for additive manufacturing that can be integrated with cutting-edge engineering technologies. We place emphasis on: 1) incorporation of functional materials, particularly those that respond via conversion of mechanical force into chemical reactivity; 2) expansion of the materials space available for AM; and 3) selective multi-material printing from “all-in-one” mixed-resin vats. As representative examples, we will discuss melt-material extrusion of custom mechanochromic filaments, novel formulations that enable inexpensive and efficient access to elastomeric components via vat photopolymerization, and progress toward parallel photo-radical/photo-cationic printing mechanisms for production of multimaterial parts. Additionally, we have recently discovered methods for direct-ink write additive manufacturing with PEEK-based suspensions, and hybrid vat photopolymerization with traditional thermoset resins via optically-patterned photothermal interface additive manufacturing. Our longer-term research objectives center on the ability to integrate mechanoresponsive materials (molecular- to nanoscale), property gradation or heterogeneity (nano- to microscale), and object geometry (micro- to mesoscale) to answer key scientific questions about the interplay between mechanics (and dynamics) of lattice structures and mechano-to-chemical coupling. 

Bio: Dr. Boydston began studying chemistry as an undergraduate at the University of Oregon under the guidance of Professor Michael M. Haley. His research focused on the synthesis and study of dehydrobenzoannulenes. After completing BS and MS degrees, he began doctoral research at the University of Texas at Austin. In 2005, Dr. Boydston joined the group of Professor Christopher W. Bielawski and was co-advised by Professor C. Grant Willson. Dr. Boydston completed his thesis research focused on the synthesis and applications of annulated bis(imidazolium) chromophores in 2007. After graduating, he moved to Pasadena, California to take an NIH postdoctoral position at the California Institute of Technology. There, he worked under the mentorship of Professor Robert H. Grubbs to develop new catalysts and methods for the synthesis and characterization of functionalized cyclic polymers. He returned to the Pacific Northwest as an Assistant Professor of Chemistry at the University of Washington in the summer of 2010. In summer 2018, he moved to the University of Wisconsin as the Yamamoto Family Professor of Chemistry. His research group currently focuses on developments in the areas of electro-organic synthesis, polymer synthesis, mechanochemical transduction, triggered depolymerization, polymers for therapeutic applications, and additive manufacturing (3D printing). His research and teaching efforts have been recognized through the NSF CAREER Award, Army Research Office Young Investigator Award, Cottrell Scholar Award, Camille Dreyfus Teacher-Scholar Award, and University of Washington Distinguished Teaching Award.