Quantifying the Structural Dynamics of Pharmaceuticals in the Glassy State.
Structural dynamics in the glassy state of two protic ionic liquids, carvedilol phosphate and procaine hydrochloride, 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 supercooled materials.
†Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
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Wojnarowska
‡Chemistry Division, Naval Research Laboratory, Code 6120, Washington, DC 20375-5342, United States.
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Roland
†Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
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Kolodziejczyk
†Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
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Swiety-Pospiech
†Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
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Grzybowska
†Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
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Paluch
amorphous pharmaceuticals; heterogeneous dynamics; ionic conductivity; physical aging; protic ionic liquid