This Faculty Early Career Development (CAREER) Program grant will support research into polymer nanocomposites or PNs, consisting of nanoparticles within a polymer matrix. These systems combine favorable properties of the polymers, e.g. light weight, mechanical toughness and flexibility, and the fillers with their high strength, electrical and thermal conductivity, in a tunable fashion. Such combinations lead to unique overall properties that cannot be achieved by conventional materials. These materials are utilized in many emerging technologies such as energy storage, biochemical sensing, flexible electronics and artificial tissue engineering important to the national prosperity and competitiveness. A primary challenge in realizing PNs involves the development of new manufacturing methods to process these materials with high resolution and precise control over filler morphology within the final product that dictates the final part properties. Emerging additive manufacturing methods, particularly direct-ink-writing (DIW), where the PN "inks" are dispensed through nozzles and deposited with high spatial control, has been shown to achieve high resolution manufacturing of PN parts with controllable filler morphologies. This award supports the fundamental research that will provide the knowledge needed for additively manufacturing PN parts having "as-designed" properties with high customizability, precision and accuracy. This capability will enable many emerging technologies critical to societal health, national security and the energy sector such as customizable biochemical sensors, high performance energy storage devices and lightweight high-strength military equipment manufacturing. The educational effort will provide a model for integration of additive manufacturing into the mechanical engineering curriculum which in turn will equip the next generation manufacturing workforce with a much needed skill-set. The outreach activities that will be realized in this project will increase the public awareness and readiness for the additive manufacturing and flexible electronics concepts.

Despite the promising potential of additive manufacturing in processing of PNs, there exists a knowledge gap in regard to relationships between raw material properties-process parameters-final part properties. This research will address this knowledge gap through an experimental and computational modeling framework that will reveal the deposition mechanisms influencing the final part properties. To this end, PN inks will be modeled through a new viscoelastic material model that incorporates the effect of temporally and spatially varying filler morphology on the bulk ink rheology. This model will be used in experimentally validated computational fluid dynamics simulations that will output critical stress and strain parameters in the deposited filaments during the printing process. Finally, studies will be conducted to understand how these model outputs translate to specific morphologies of nanoparticles as well as the electrical and mechanical properties of the manufactured parts.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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Washington State University
United States
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