Solid monolayers of glycerides adsorbed on the surface of graphite powder

We report a calorimetric study of the formation of solid monolayers of fatty acid glycerides on the surface of graphite. Solid monolayer formation is observed at temperatures significantly higher than the bulk melting point for some species, while for others these melting points are rather similar. The variation of monolayer melting point as a function of alkyl chain length, number of alkyl chains and the extent of unsaturation is reported. There are a number of interesting and unexpected effects in the observed behaviour as hydroxyl groups are replaced by alkyl chains on passing from mono-, to di- and tri-glycerides.

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► DSC identification of solid monolayer formation for glycerides on graphite surface.
► Monolayer stability was quantified in terms of the molecular architecture.
► Glycerides with longer fatty acid chain lengths form more stable solid monolayers.
► Unsaturation reduces the monolayer stability.
► Surprisingly increases as –OH groups are exchanged for alkyl chains.