Abstract: Different length and time scales of polymer dynamics are manifested in everyday life as thermophysical properties, such as viscosity and glass transition temperature. Recently, we observed a hidden low-frequency relaxation typically masked by the DC conductivity signal in dielectric spectroscopy. This newly identified relaxation process, termed the “slower” process, occurs at a rate slower than well-known a-relaxation. We further demonstrated that the slower process can explain anomalous rheological properties of nanocomposite loaded with ultra-small nanoparticle, polyhedral oligomeric silsesquioxane (POSS). In this talk, I will discuss the potential explanation for the molecular-level mechanism of the slower process and recent experimental investigations.
References:
(1) Young, W. W.; Katsumata, R. Intermediate Polymer Relaxation Explains the Anomalous Rheology of Nanocomposites with Ultrasmall Attractive POSS Nanoparticles. ACS Polym. Au 2023, 3 (6), 466–474. https://doi.org/10.1021/acspolymersau.3c00020.
(2) Young, W. W.; Tabuchi, H.; Iguchi, R.; Konishi, T.; Fukao, K.; Katsumata, R. A Hidden Relaxation Process in Poly(2-Vinylpyridine) Homopolymers, Copolymers, and Nanocomposites. Macromolecules 2022, 55 (15), 6590–6597. https://doi.org/10.1021/acs.macromol.2c00789.
Bio: Reika Katsumata is an assistant professor in the Polymer Science and Engineering Department at UMass Amherst, who received a B.E. in Organic and Polymeric Materials from the Tokyo Institute of Technology and a Ph.D. in Chemical Engineering from the University of Texas at Austin. Leading the Katsumata Research Group at the intersection of chemical engineering and materials science, she focuses on revealing material performance that is otherwise impossible by designing extremely confined soft/hard interfaces. Her three main research thrusts involve leveraging rapid thermal annealing for functional porous materials and defect-healing/doping 2D materials, developing reprocessible crosslinked polymers through ultrasound-mediated bond-exchange reactions for sustainability, and laying the foundation by understanding polymer dynamics and wettability at interfaces.
