Phase behavior of the monoerucin/water system

Area of Science:

• Lipid physical chemistry
• Materials science
• Biophysics

Background:

• Monoerucin, a monoacylglycerol, exhibits complex phase behavior in water.
• Previous studies presented conflicting temperature-composition phase diagrams for monoerucin/water systems.
• Discrepancies arose from differing methodologies, including consistency, light microscopy, and X-ray diffraction.

Purpose of the Study:

• To resolve controversies regarding the thermotropic and lyotropic properties of monoerucin/water.
• To construct an accurate equilibrium phase diagram using the isoplethal diffraction method.
• To characterize the phase microstructure dependence on hydration and temperature.

Main Methods:

• Isoplethal X-ray diffraction for phase diagram construction.
• Differential scanning calorimetry (DSC) for thermal analysis.
• Polarizing light microscopy (PLM) for microstructure confirmation.

Main Results:

• Confirmed the presence of the inverted hexagonal (HII) phase (10-22% water, 35-125°C) and its coexistence with excess water (>24% water).
• Identified lamellar crystal (Lc) phase dominance at low temperatures.
• Observed lamellar liquid crystal (Lα) and cubic-Ia3d phases at intermediate temperatures and hydration levels.

Conclusions:

• The study provides a definitive equilibrium phase diagram for monoerucin/water.
• Phase behavior is intricately linked to temperature and hydration levels.
• Understanding these phases is crucial for applications involving monoerucin-based systems.