Materials World Network: Polymers Dynamics in the Presence of Nanoparticles

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This research helps provide a fundamental understanding of polymer dynamics in the presence of nanoparticles using a coordinated experimental and theoretical approach. This Materials World Network team from the University of Pennsylvania and Durham University has considerable experience in polymer nancomposites and dynamic properties, and is working together in exploring polymer diffusion and rheology in these fascinating and complex materials. This team recently found a dramatic example of how polymers behave differently in the presence of nanoparticles, wherein polymer diffusion first slowed and then recovered with the addition of nanoparticles. Research efforts are focusing on three aspects of polymer nanocomposite dynamics. (1) Establishing the underlying mechanism of polymer diffusion in nanocomposites. A variety of studies are underway that explore the impact of nanoparticle / polymer interactions, nanoparticle orientation, relative size of the polymer and nanoparticle diameter, and nanoparticle shape. (2) Relating the polymer and nanoparticle diffusion studies to rheological measurements including linear viscoelastic measurements, zero-shear viscosity, plateau modulus and relaxation times. Polymer diffusion and polymer rheology are intimately related through fundamental relaxation parameters, so our goal is to reconcile these two measures of polymer dynamics in polymer nanocomposites. (3) Refining and extending our theoretical description of the polymer dynamics in the presence of nanoparticles. One critical extension is to adjust the monomeric friction coefficient near the particles to evaluate the importance of enthalpic interactions on diffusion.The research team is well-positioned for groundbreaking insights into the physics of polymer nanocomposites that are likely to have a positive impact on the emerging industry of polymer nanocomposites. Interactions include meetings, bi-monthly teleconferences, monthly reports, data sharing via a secure website, regular international trips, and remote access to experimental equipment. This project also addresses the needs of women in science and engineering by establishing professional problem-solving groups for women faculty and graduate students as a means to collectively address the challenges and opportunities in science and engineering careers. Furthermore, undergraduates from both the University of Pennsylvania and Durham University participate in the research activities as well as consider the business aspects of launching new materials.This Materials World Network research is supported by the DMR Polymers Program and the DMR Office of Special Programs.