O. Mykhaylyk, V. Castelletto, I. Hamley
May 1, 2004
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Influential Citations
7
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Journal
European Journal of Lipid Science and Technology
Abstract
Polymorphic transformations of 1,3-distearoyl-2-oleoyl glycerol (SOS) at low temperatures (10 °C–30 °C) have been studied by time-resolved synchrotron X-ray diffraction (XRD) measurements at small and wide angles. Three structures have been identified: α-phase structure forms by quenching to 10 °C from the liquid state, a metastable structure formed simultaneously with α-phase and γ-phase formed at 30 °C during α-melt-mediated crystallisation as well as at the pre-melting temperature (22.5 °C) of the α-phase when the coexistence of two phases (α and γ) is observed. The metastable structure produces three broad peaks in XRD patterns at small angles (one strong and two weak peaks corresponding to d-spacings of ∼4 nm, ∼12 nm and ∼1.5 nm respectively) and a peak in X-ray diffraction patterns at wide angles (0.42 nm). A model is proposed for the metastable structure based on a combination of double- and triple-chain packing of SOS molecules due to the similar length of alkyl chains (stearoyl and oleoyl) in the molecules.