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The ascorbyl palmitate-polyethyleneglycol 400-water system phase behavior
Luciano Benedini1, Paula V Messina, Santiago D Palma
1Departamento de Química e INQUISUR, Universidad Nacional del Sur, CONICET, Bahía Blanca, Argentina.
Colloids and Surfaces. B, Biointerfaces
|October 15, 2011
Summary
Ascorbyl palmitate (Asc16) forms cubic and lamellar liquid crystalline phases in PEG 400-water mixtures. Increasing PEG 400 concentration shifts these phase boundaries to lower temperatures and surfactant concentrations.
Area of Science:
- Physical Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Ascorbyl palmitate (Asc16) is a lipid-soluble derivative of ascorbic acid.
- Polyethylene glycol 400 (PEG 400) is a versatile polymer used in various formulations.
- Understanding the phase behavior of Asc16 in PEG 400-water mixtures is crucial for formulation development.
Purpose of the Study:
- To investigate the phase behavior of Ascorbyl palmitate (Asc16) in Polyethylene glycol 400 (PEG 400)-water mixtures.
- To construct phase diagrams for Asc16/PEG 400/water systems at various PEG 400 concentrations.
- To identify the types and stability regions of liquid crystalline mesophases formed.
Main Methods:
- Differential Scanning Calorimetry (DSC) to analyze thermal transitions.
- Polarizing Microscopy (PM) for visual identification of mesophases.
- Systematic variation of Asc16 and PEG 400 weight fractions.
Main Results:
- Complete phase diagrams were determined for PEG 400-water mixtures containing Asc16.
- Cubic and lamellar mesophases were identified in specific regions of the phase diagrams.
- The addition of PEG 400 shifted liquid crystalline domain limits to lower temperatures and surfactant concentrations, particularly at PEG 400 concentrations >= 50%.
Conclusions:
- PEG 400 significantly influences the phase behavior of Asc16 in aqueous systems.
- The formation and stability of cubic and lamellar mesophases are dependent on Asc16 and PEG 400 concentrations.
- Hydrated Asc16 crystals (Asc16·2·6H2O) were observed, and heating them resulted in waxy crystals with retained bilayer structure.
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