Quantifying the Structural Dynamics of Pharmaceuticals in the Glassy State

ABSTRACT: Structural dynamics in the glassy state of two protic ionic liquids, carvedilol phosphate and procaine hydro-chloride, were characterized from analysis of changes in the conductivity relaxation times during physical aging. The obtained relaxation times, having a magnitude exceeding feasible experimental time scales and thus not directly measurable, are consistent with published data from a method that relies on the presence of a secondary relaxation. We also observe a narrowing of the relaxation dispersion, specific to higher frequencies, that is a consequence of the heterogeneous dynamics of deeply super-cooled materials. SECTION: Glasses, Colloids, Polymers, and Soft Matter The irony of the ∼100 years of research on the glasstransition is that so little of it is concerned with glasses per se. This is the case even though the vitreous state is associated with distinct properties that may help solve the glass transitio