The ascorbyl palmitate?polyethyleneglycol 400?water system phase behavior

BENEDINI LUCIANO, ; MESSINA PAULA; PALMA SANTIAGO; ALLEMANDI DANIEL; SCHULZ PABLO

COLLOIDS AND SURFACES B-BIOINTERFACES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 89 p. 265 - 270

0927-7765

Ascorbyl palmitate (Asc16) in polyethyleneglycol 400 (PEG 400)?water mixtures at weight fractions (w/w) between 0.05 and 1.0 were studied by differential scanning calorimetry (DSC) and polarizing microscopy (PM) at different temperatures. The employed PEG 400-water proportions were: 25-50% and 75% of polymer. A complete phase diagram was determined for each PEG 400-water mixture. A cubic mesophase and two (probably three) lamellar mesophases were detected in different regions of the phase diagrams. The addition of PEG 400 to the Asc16-water system shifts the limits of the liquid crystalline domains to lower temperature and surfactant concentration. At weight action of PEG 400 = 50%, the limits of the domain of existence of cubic mesophase shift to low surfactant concentration compared with water-rich systems. The hydrated crystals are Asc16.2·6H2O. If the proportion of ater is lower than that value, a mixture of hydrated and anhydrous crystals appears. Heating these crystals produce waxy crystals having elted hydrocarbon bilayers retaining their crystalline structure because the polar bilayers are still rigid.