Vitrification of trehalose by water loss from its crystalline dihydrate

Trehalose dlhydrate, on careful dehydration below its fusion point, retains its original crystal facets but becomes X-ray amorphous, an unusual example of direct crystal-to-glass transformation. From DSC studies, the glass obtained by this route seems to be of abnormally low enthalpy, but after an initial scan, the normal form of glass transition is exhibited, with T_g=115°C, a higher value than previously reported. We give a preliminary thermal and mechanical characterization of this material and find it to be a very fragile liquid. The high T_g is shown to rationalize the exceptionally high water content of the trehalose+water solution that vitrifies at ambient temperature (i.e. T_g=298 K), and hence helps explain its use by Nature as a desiccation protectant. The spontaneous vitrification of crystalline materials during desolvation is related to the phenomenology of pressure-induced or decompression-induced vitrification of crystals via the concept of limiting metastability.