Density Measurement of the Polymorphic Forms of POP, POS and SOS

The density of liquid and polymorphic crystalline forms of 2-oleoyl-1, 3-dipalmitoylglycerol (POP), 2-oleoyl-1, 3-rac-palmitoyl-stearoylglycerol (POS), and 2-oleoyl-1, 3- distearoylglycerol (SOS) were measured by gas pycnometer. An 0.18 nm3 decrease in molecular volume was observed in all triacylglycerols, corresponding to structural changes in the most stable form of β1 of the three triacylglycerols. More precisely, the saturated and unsaturated fatty acyl moieties in the triacylglycerols showed no monotonous change in volume.In sample preparation, density of each polymorphic forms was observed to be highest by symple melt cooling. For melt mediated transformation, and solid state transformation, the values of this parameter were less.