Ultra-micro Liquid Crystal in Cosmetic Emulsion with Excellent Moisture Retention and Delivery Selectivity

Compared with ordinary emulsified cosmetics, liquid crystal emulsified cosmetics have obvious advantages. In this paper, an ultra-micro liquid crystal (ULC) emulsion with particle size less than 4 μm was successfully synthesized using a simple oil-in-water emulsification method, and large liquid crystal (LLC) and non-liquid crystal (NLC) emulsions were also prepared as controls. Three kinds of emulsions were examined by polarizing microscopy, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM). Rheological tests, in vivo experiments, reconstructed Raman maps tracking selected markers and thermogravimetric (TG) results showed that the ULC emulsion expressed excellent viscoelasticity, long-term moisturizing property with barrier function and better selective delivery of active substances compared with LLC and NLC emulsions. Molecular dynamics simulation on the ULC system and deuterium order parameter plots respectively indicated that GYY (glyceryl stearate citrate) showed a tendency to form a stable structure by reducing the total interaction energy and enhancing system lamellar ordering. This work not only demonstrates the great potential of ultra-micro liquid crystals in for commercial applications in cosmetics but also offers a deeper understanding of the intrinsic properties and growth mechanisms of ultra-micro liquid crystals at the microscopic level.