Molecular Motions in Supercooled Liquids

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Professor Mark Ediger of the University of Wisconsin Madison is supported by the Theoretical and Computational Chemistry program to perform thermodynamic studies of the structure and dynamics of supercooled liquids and the glass/liquid transition. The PI uses neutron forward recoil spectrometry and neutron reflectivity to assess self-diffusion in thin bilayer samples of deuterated and nondeuterated molecules. Samples include small polar glass forming molecules such as glycerol, propylene carbonate and water. Secondly, a solid state NMR method new to this application is being used on several supercooled liquids and films providing structural information as a function of temperature. New types of data will provide important benchmarks for theoretical efforts in predicting phase transitions in condensed phases.Despite having a long history, the area of supercooled liquids and the glass/liquid transition has many fundamental unanswered questions about the nature of molecular motions near the transition point and the influence of structure on properties of glass forming materials. An improved understanding of the glassy state will have impact on materials applications including polymer science.