Stability in Glasses: New Materials and New Insights
Glasses are ubiquitous across materials types and technological applications but their structure – property – processing relationships and underlying fundamental physics remain poorly understood. IRG 1 uses cross-fertilization of ideas and techniques from organic and inorganic glasses to address fundamental problems in glass science through the lens of stability. Glasses of the same composition can be created in states of widely varying thermodynamic and kinetic stability. The IRG seeks to use these materials to develop fundamental stability-structure-property relationships for glasses. Efforts include establishing control over stability in organic and inorganic glasses; understanding the structures associated with varying states of stability ; discovering the molecular nature of polyamorphism – the existence of two stable liquid states of the same substance; and determining the relationship between the structure and dynamics of liquids as they cool into the glassy state. The IRG integrates theory, simulations, and experiments to expand the range of ultrastable glassy materials and to enable new applications in areas as diverse as hard coatings and quantum information.
IRG 1 Highlights
Many kinds of materials, including thin films, are created by adding atoms or molecules to a surface. As a result, understanding how molecules move along a surface is an important part of making new materials. In general, diffusion and crystal growth are much faster on the surface of glasses than in the interior. How much faster depends on how big the molecules are, and how many hydrogen bonds the surface molecule has to the bulk, as MRSEC researchers have recently discovered. This model works for many different molecules, giving a quick and easy way to predict surface motion and guide the synthesis of new materials.June 26, 2019
Creating glassy thin films of organic molecules at different temperatures changes both their stability in the glassy state – their density, and how hard they are to melt – and it changes how the molecules in the films are arranged – whether they tend to lie down flat on the surface or stand straight up. Wisconsin MRSEC researchers have shown that these changes in stability and average molecular orientation also change the mechanical properties of the film, including how stiff it is and how hard it is.June 11, 2019