Molecular Orientation in Stable Glasses of Indomethacin

TitleMolecular Orientation in Stable Glasses of Indomethacin
Publication TypeJournal Article
Year of Publication2012
AuthorsDalal, S. S., and M. D. Ediger
JournalJournal of Physical Chemistry LettersJournal of Physical Chemistry LettersJournal of Physical Chemistry Letters
Volume3
Pagination1229-1233
Date PublishedMay
Type of ArticleArticle
ISBN Number1948-7185
Accession NumberWOS:000304073800001
KeywordsDEPENDENCE, DOUBLE REFRACTION, KINETIC STABILITY, LIQUIDS, RELAXATION, TEMPERATURE, TOLUENE, TRANSFORMATION, TRANSITION, VAPOR-DEPOSITION
Abstract

Spectroscopic ellipsometry has been used to measure the properties of indomethacin prepared by physical vapor deposition at T-substrate/T-g = 0.78, 0.84, and 0.90. The as-deposited glasses exhibited high kinetic stability and had densities 0.8-1.2% higher than the ordinary glass prepared by cooling the liquid at 1 K/min. Deposition at the higher temperatures yielded glasses with positive birefringence (up to Delta n = 0.028), while the lowest-temperature sample was negatively birefringent (Delta n = -0.015). These results indicate that substrate temperature can be used to manipulate molecular orientation in high-density and high-stability glasses. The data for the supercooled liquid and the ordinary glass of indomethacin are reasonably consistent with the Lorentz-Lorenz equation, but significant deviations are noted with the as-deposited materials.

DOI10.1021/jz3003266
Short TitleJ. Phys. Chem. Lett.J. Phys. Chem. Lett.
Alternate JournalJ. Phys. Chem. Lett.