Observing how Glassy Surfaces Flow
Glasses can be rather odd materials and part of the reason for that is to do with how they transition from a solid to a liquid. There are temperatures at which they are clearly a solid and clearly a liquid, but in between it can be hard to tell. Researchers at the University of Waterloo have recently found the answer to a twenty-year-old debate concerning the surfaces of glassy materials.
About twenty years ago, it was discovered that at temperatures a glass should be a solid, the surfaces of some were flowing like liquids. Since then researchers have been working to find how this is possible. Though most people will associate glasses with windows, many materials, including metals and polymers can be glasses, as the term refers to a disordered molecular structure. For this work, the researchers were working with a glass of polystyrene. Thin slices of the glass were stacked to form staircase-like steps just 100 nm high. The researchers then observed and measured how the steps changed shape over time, and thanks to the simple 2D profile of the surface, they were able to numerically model it.
With this understanding of glasses, researchers can consider how nanostructures made of a glass will change over time. This could impact the use of thin film coatings and how small some nanoscale devices and circuitry can be made.
Source: University of Waterloo