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Glycolipids prepared from palm kernel oil, PKO, in tropical regions represent an excellent opportunity to develop new surfactant formulations for cosmeceutical and pharmaceutical applications while contributing to sustainable economies. Here we report the synthesis of a new mannoside obtained from palm kernel oil, aManPKO, and we characterise its thermotropic properties by using DSC, POM, SAXS, WAXS, FT-IR and broadband dielectric spectroscopy. aManPKO exhibits a monotropic smectic phase with a partially interdigitated bilayer structure, similar to its major unsaturated component, the oleyl mannoside with a C18:1 monounsaturated alkyl chain. The smectic phase of aManPKO vitrifies below room temperature, which is associated to the C18:1 component, but also to the activation of short-range motions, ~4 Å, by cleavage of strong hydrogen bonding between the polar heads of the mannosides. The stability of the liquid crystal phase, on the other hand, is linked to the presence of weak hydrogen bonding, whose breakage leads to the activation of long rate motions in the range of the layer distances, ~39 Å. [ABSTRACT FROM AUTHOR]

Abstract The sugar anomeric effect on the thermotropic phase transition of stearyl glucoside was investigated. Standard analysis to study the phase transition through differential scanning calorimetry (DSC), and optical polarizing microscopy (OPM) was applied. In addition, small- and wide-angle X-ray scattering (SWAXS) and impedance spectroscopy (IS) were used to elucidate the phase structural information and the dielectric response of the glycolipid self-assembly system, respectively. A distinctive solid-to-liquid crystal phase transition of α - and β -stearyl glucoside was observed. At ambient temperature we observed semi-crystalline structure for the former and gel phase for the latter. α -Stearyl glucoside showed only one-step transition from semi-crystal to lamellar liquid crystal phase. In contrast, the gel phase of β -stearyl glucoside showed several distinct transition states prior to lamellar liquid crystal phase. Here the underlying reason for the observed β -stearyl glucoside polymorphism possibly involved strong intermolecular interaction originating from the combination of interlayer H-bonding and intralayer van der Waals forces. Graphical abstract Unlabelled Image Highlights • Sugar stereochemistry affects the lipid packing and hydrogen bond of the glycolipid. • Both glycolipid anomers form different solid phase structure at ambient temperature. • α -Anomer shows one step of semi-crystalline–to–liquid crystalline phase transition. • β -Anomer shows multiple steps of gel–to–liquid crystalline phase transition. [ABSTRACT FROM AUTHOR]