Molecular view of the isothermal transformation of a stable glass to a liquid

TitleMolecular view of the isothermal transformation of a stable glass to a liquid
Publication TypeJournal Article
Year of Publication2008
AuthorsSwallen, S. F., K. L. Kearns, S. Satija, K. Traynor, R. J. McMahon, and M. D. Ediger
JournalJournal of Chemical Physics
Volume128
Start Page214514
ISBN Number0021-9606
Accession NumberWOS:000256527500033
KeywordsAROMATIC HYDROCARBONS, CRYSTALS, FICKIAN DIFFUSION, FILMS, INTERFACE, NAPHTHYLBENZENE, PHYSICAL PROPERTIES, TRANSITION
Abstract

We have used neutron reflectivity to measure translational motion on the nanometer length scale in exceptionally stable glasses of tris(naphthylbenzene). These glasses are prepared by vapor deposition onto a substrate held somewhat below the glass transition temperature (T(g)=342 K). When the most stable samples are annealed at 345 K, no translational motion is observed on the 12 nm length scale for over 10 000 s and full mixing requires more than 60 000 s. For comparison, the equilibrium supercooled liquid mixes in 1000 s at this temperature and on this length scale. These measurements provide insight into the mechanism by which a stable glass transforms into a liquid. "Melting" of the stable glass appears to occur by the growth of liquid regions into the surrounding glassy matrix, perhaps by a surface-initiated growth process. At 345 K, translational motion in the stable glass is at least 100 times slower than motion in the supercooled liquid. (C) 2008 American Institute of Physics.

DOI10.1063/1.2919570
Alternate JournalJ. Chem. Phys.