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UNT Insider | November 2009 Issue | UNT professor helps find new way to model glass formation

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UNT professor helps find new way to model glass formation

From a UNT News Service press release

Dr. Zhibing Hu

A UNT researcher has helped develop a new and potentially better way to model the formation of glass, which could lead to improvements in the material's design and manufacturing.

Zhibing Hu, a Regents Professor of physics, worked with a team of researchers from Harvard and Columbia universities on the findings, which are detailed in the November issue of Nature. The team was led by Dr. David Weitz of Harvard.

"The insight gained from this study can help us understand the origin of dynamic processes in glassy systems," Hu says. "For example, we found that elastic energy plays an important role in glass formation, something that was not previously determined."

Window glass is usually made by melting a mixture of silica, or sand, and other additive substances. Then, the liquid is cooled to become a rigid solid whose molecules, though they have stopped flowing, are not permanently locked into a crystal structure.

Although the methods for making glass have been known for centuries, scientists had yet to understand the principles that govern the rate at which glasses solidify.

The Nature article describes a method to enhance the basic understanding of glass formation using a suspension of soft colloids as a model. A colloidal suspension is a type of chemical mixture in which small particles are dispersed evenly throughout another. Milk is one of the most familiar colloidal suspensions.

Hu helped design the soft colloids, which are composed of hydrogel materials that are soft and deformable, similar to Jell-O.

When more colloids are added to the system, movement is restricted and the colloids flow more slowly. So the rate at which colloids solidify can be probed by increasing their volume.

The advantage of this approach to studying glasses directly is size. The colloid particles are several hundred times bigger than a molecule of a glass, and dynamics of the colloidal suspension can be easily characterized with a light scattering method.

Hu and the other researchers found that the rate at which colloids solidify depends on the softness — or elasticity — of the colloids, which means elastic energy plays an important role in glass formation.

Researchers say the exploration of other soft colloids could further the understanding of glass formation.

Sarah Bahari with UNT News Service can be reached at Sarah.Bahari@unt.edu.

Read other stories in this issue:

November 2009

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