Seminar 10/17/2012 - Connie Roth, Emory University: Exploring the Different Length Scales Affecting Glassy Dynamics in Polymer Films
Bio: Prof. Roth earned her B.S. in Physics from McMaster University and her M.S. and Ph.D. from the University of Guelph in Canada. Following a post-doctoral position at Northwestern University, she joined the faculty at Emory University in Fall 2007. She is the inaugural recipient of the 2009 UKPPG/DPOLY Polymer Lecture Exchange by the American Physical Society and received an NSF CAREER award in 2012. Roths research studies dynamics and heterogeneity in polymer glasses, miscibility of polymer blends, and the photophysics of conducting polymers.
Abstract: Understanding and controlling the long-term stability of glassy polymer films are important for a range of technological applications from gas separation membranes to dielectric layers. Glassy materials held at temperatures below their glass transition temperature (Tg) are in an inherently non-equilibrium state that undergo structural relaxation (physical aging) leading to a logarithmic decrease in the free volume of the material over long times, and a host of related property changes. The study of glassy dynamics in confined systems such as thin films can be used to interrogate the length scales associated with dynamical heterogeneity and other open questions limiting our fundamental understanding of the glass transition. This talk will cover how boundary effects such as a free surface in nanoconfined polymer films can reduce Tg by many tens of degrees Celsius and correspondingly alter the physical aging dynamics of the material. In addition, we address how the presence of intended or unintended stresses on the material during the formation of the glassy state can alter the subsequent physical aging rate of the glass. Comparisons of these phenomena across different glass forming materials, e.g., small molecular glasses, colloidal glasses, and jammed granular systems, will also be discussed. Some effects are common across multiple glass forming systems, while others are uniquely polymer related.
All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.
Location: Bowen Hall Auditorium
Date/Time: 10/17/12 at 12:00 pm - 10/17/12 at 1:00 pm
Category: PRISM/PCCM Seminar Series