CAREER: Direct Measurement and Manipulation of Colloidal Interactions and Dynamics in Template Directed Photonic Crystal Assembly
This proposal is concerned with measurement and manipulation of colloidal interactions involved in the assembly of single photonic colloidal crystals on interfacial templates and in the presence of external fields. The objective is to understand fundamental mechanisms linking colloidal forces and hydrodynamic interactions to formation of thermodynamic structures and kinetic pathways in interfacial "self-assembly" and "driven assembly" processes. A central task in this work is to combine total internal reflection, video, and confocal scanning laser microscopy techniques to measure particle-particle, particle-template, and particle-field interactions in increasingly complex interfacial colloidal systems ranging from single particles to concentrated three dimensional dispersions. With the ability to directly measure many-body interfacial interactions, weak attractive forces relevant to colloidal crystal self-assembly on templated substrates will be controlled by finely tuning temperature and specific ion dependent polymeric dispersion forces. To avoid formation of irreversible gel and arrested glass structures, AC electrophoretic driven-assembly of intermediate metastable crystalline structures will be used to manipulate the kinetic route in photonic crystal assembly processes. Monte Carlo and Stokesian dynamics simulations will be used to understand how to form optimal equilibrium particle configurations and how to control dynamics to avoid kinetic traps. Each proposed experiment provides complementary information on how to manipulate colloid systems to assemble large single interfacial photonic crystals, which has broad significance for any technology that seeks to assemble arbitrary nano- and micro- structured materials and devices on substrates. The intellectual merit of the proposed career plan is based on its fundamental significance to manipulating ordered interfacial structures on colloidal length, time, and energy scales, which are inherently intermediate to molecular and macroscopic systems and therefore of utmost importance to nano- science and technology.
The educational plan in this proposal involves extensively incorporating image, video, and animations from microscopy/simulation experiments in my research group into a colloidal complex fluids/nanotechnology course for both undergrad and grad students. The objective is to use visualization and multimedia tools to help students with different learning styles quickly develop mental pictures necessary to retain a physically intuitive understanding of colloid science. Because I employ optical microscopy to explore fundamental colloidal phenomena in my research, directly incorporating images and videos into class lectures is a natural way for me to passionately teach students using "real" multiscale research examples, which is also consistent with chemical engineering curriculum reform initiatives. As part of developing visualization tools, a virtual reality presentation in the Immersive Visualization Center at Texas A&M will be delivered as a special class lecture, and will also be used as a frequent outreach tool to underrepresented groups, k-12 students, and teachers through existing NSF sponsored campus programs. To assess the effectiveness and optimize the implementation of classroom multimedia tools, collaborators in School Psych./Ed. Tech. at Texas A&M will help to evaluate cognitive and pedagogical aspects of my visualization based lectures, with findings disseminated in education journals and at national conferences. The broader impact of the proposed career plan is related to the direct use of microscopy and simulation visuals from my research in courses and outreach programs to improve the depth, rate, retention, and enjoyment of learning in the training of future engineers and in improving scientific literacy of the general public.
