Hiking down the energy landscape: Progress toward the Kauzmann temperature via vapor deposition

TitleHiking down the energy landscape: Progress toward the Kauzmann temperature via vapor deposition
Publication TypeJournal Article
Year of Publication2008
AuthorsKearns, K. L., S. F. Swallen, M. D. Ediger, T. Wu, Y. Sun, and L. Yu
JournalJournal of Physical Chemistry B
Volume112
Pagination4934-4942
ISBN Number1520-6106
Accession NumberWOS:000255104900013
KeywordsAROMATIC HYDROCARBONS, BOND LATTICE, FREE-VOLUME, GLASS-FORMING LIQUIDS, INDOMETHACIN POLYMORPHS, ORGANIC MATERIALS, PHYSICAL PROPERTIES, STRUCTURAL RELAXATION, SUPERCOOLED LIQUIDS, TRANSITION
Abstract

Physical vapor deposition was employed to prepare amorphous samples of indomethacin and 1,3,5-(tris)-naphthylbenzene. By depositing onto substrates held somewhat below the glass transition temperature and varying the deposition rate from 15 to 0.2 nm/s, glasses with low enthalpies and exceptional kinetic stability were prepared. Glasses with fictive temperatures that are as much as 40 K lower than those prepared by cooling the liquid can be made by vapor deposition. As compared to an ordinary glass, the most stable vapor-deposited samples moved about 40% toward the bottom of the potential energy landscape for amorphous materials. These results support the hypothesis that enhanced surface mobility allows stable glass formation by vapor deposition. A comparison of the enthalpy content of vapor-deposited glasses with aged glasses was used to evaluate the difference between bulk and surface dynamics for indomethacin; the dynamics in the top few nanometers of the glass are about 7 orders of magnitude faster than those in the bulk at T-g - 20 K.

DOI10.1021/jp7113384
Alternate JournalJ. Phys. Chem. B