[Structure of cholesterol-containing creams].

Area of Science:

• Colloid and surface chemistry
• Materials science
• Physical chemistry

Context:

• Understanding the complex colloidal structures of multi-component cream formulations is crucial for developing stable and effective products.
• Emulsion stability and water-holding capacity are key performance indicators for cosmetic and pharmaceutical creams.

Purpose:

• To investigate the colloidal structure of a four-component system (cholesterol, fatty alcohol, petrolatum, water) for water-in-oil (w/o) creams.
• To correlate structural features with formulation parameters like temperature, fatty alcohol chain length, and component concentrations.
• To characterize the liquid crystalline and crystalline phases present in the cream systems.

Summary:

• Creamy w/o systems with varying structural features were prepared by adjusting temperature, fatty alcohol chain length, and component concentrations.
• The structure comprises liquid phases (water, liquid hydrocarbons), liquid crystalline phases (cholesterol-fatty alcohol), and crystalline phases (hydrocarbons, eutectic mixtures, hydrates).
• Lamellar liquid crystals, characterized by polarized light microscopy and X-ray diffraction, form within specific cholesterol-fatty alcohol molar ranges and are stabilized by water incorporation.
• Maximum water incorporation capacity is achieved in systems with minimal crystalline phases, primarily the petrolatum network, and fully dissolved surfactants.

Impact:

• Provides fundamental insights into the phase behavior and structural organization of complex cream formulations.
• Identifies key formulation parameters influencing the stability and water-binding properties of w/o emulsions.
• Offers guidance for the rational design of advanced cream bases with enhanced stability and performance characteristics.