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Dr. Zahra Fakhraai, University of Pennsylvania

Description



Title: Understanding Glass Transition Through Interfacial Properties

Description: Glass transition, the process of falling out of equilibrium for super-cooled liquids has been a subject of intense theoretical debate in condensed matter physics, with few experiments that can distinguish between these various theories. Unlike crystallization, a distinct thermodynamical phase is hard to achieve in amorphous liquid packings.

Free surfaces and interfaces are strong perturbations that can affect properties of glassy systems over length scales much longer than the intermolecular interaction potential. A fundamental understanding of the magnitude and length scale of these effects can allow us to understand the glass transition phenomenon on a fundamental level and engineer nano-scaled materials with unique properties. In this presentation I show two examples of such effects and their use in producing thermally and kinetically stable glass materials. I discuss how free surfaces can template dynamics over length scales as large as 30 nm, and present indication of a dynamical phase transition in bulk systems. I also demonstrate
that strong nano-confinement can significantly slow the glass dynamics in highly-loaded nanocomposites, due to purely entropic reasons, resulting in significant changes in thermodynamical properties such as degradation kinetics and reaction pathways. We discuss the role of various parameters in achieving thermally and kinetically stable glass states using both types of interfacial phenomena.

Speaker: Dr. Zahra Fakhraai

Institute: University of Pennsylvania

Location: ABB-102

Website - https://www.chem.upenn.edu/profile/zahra-fakhraai
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McMaster University - Faculty of Science | Physics & Astronomy