Georgetown Physicist Studies Glass Transition in Polymers

A paper co-authored by Georgetown College of Arts and Sciences professor Peter Olmsted has been published in the American Physical Society journal Physical Review X. Conducted in collaboration with Olmsted’s colleagues at the University of Leeds, the research examines how polymers become glassy at the molecular level. 

Olmsted, a theoretical physicist who studies soft materials, works at the intersection of physics, materials science, chemical engineering and biology. The paper provides a fresh look into glass transition, a veritable Gordian knot for materials scientists. 

“Since my Ph.D., I’ve been working on polymer problems of various sorts–crystallization of polymers, phase separation of polymers and what happens to polymers under flow,” explains Olmsted. “I’ve purposefully stayed away from the glass transition because it’s one of those angels-dancing-on-the-head-of-a-pin problems where you can argue endlessly because the experiments are so difficult to do and there are so many competing theories.”

The Flex Zone

The paper identifies the mechanisms by which the molecular weight of a molecule affects its glass transition. The research team has demonstrated that the size and shape of a polymer chain are linked to the process of transitioning to or from glass.

The framework for their analysis is the first that explicitly incorporates the flexibility of a molecule into a model of its glass transition. 

“We have a handle on how the fundamental, cooperative process of a chain feeds into the overall relaxation of the chain, which makes it become a glass,” Olmsted explains. “Now, you can begin devising new chemistries for polymers that you’d like to use, say in batteries.” 

Preparing for Polymer Production

This research has tremendous implications for a slew of industries that rely on polymers for their everyday operations. 

“Probably 50 to 70 percent of the polymers that we use are in a glassy state,” Olmsted explains. “As an example, venues for live events such as hockey games are reliant on glassy polymers because they don’t want their barriers to shatter when a puck makes contact.“ 

The team expects this novel framework for understanding glassy polymers to generate interest from various industries as it can refine and improve processes for creating durable substances with glassy properties. 

Olmsted, who led the Soft Matter Physics group at Leeds before joining the faculty at Georgetown, is the Joseph Ives Chair in Physics and heads the Institute for Soft Matter Synthesis and Metrology. 

-by Hayden Frye (C’17)