Self-diffusion of the amorphous pharmaceutical indomethacin near T-g

TitleSelf-diffusion of the amorphous pharmaceutical indomethacin near T-g
Publication TypeJournal Article
Year of Publication2011
AuthorsSwallen, S. F., and M. D. Ediger
JournalSoft Matter
Volume7
Start Page10339
ISBN Number1744-683X
Accession NumberWOS:000296026700066
KeywordsAROMATIC HYDROCARBONS, FLUCTUATIONS, FORMING LIQUIDS, GLASS-TRANSITION TEMPERATURE, heterogeneous dynamics, MOLECULAR MOBILITY, O-TERPHENYL, PHYSICAL PROPERTIES, STABILITY, SUPERCOOLED TRIS-NAPHTHYLBENZENE
Abstract

Secondary ion mass spectrometry has been utilized to measure self-diffusion coefficients D in supercooled indomethacin from 310 K to 350 K (T-g = 315 K). Over this temperature range, D varies from 10^-17 cm^2 s^-1 to 10^-11 cm^2 s^-1. The temperature dependence of D is significantly weaker than the temperature dependence of the viscosity or the structural relaxation time tau(alpha), and scales as tau(-0.76)(alpha). At T-g, D is enhanced by more than a factor of 100 in comparison to the viscosity and the expectations of the Stokes-Einstein equation. For deeply supercooled indomethacin, the temperature dependence of D matches the temperature dependence of crystal growth rates for all three polymorphs.

DOI10.1039/C1SM06283B