Formation and characterization of microemulsion with novel anionic sodium N-lauroylsarcosinate for personal care

Abstract

Microemulsions are unique clear systems comprising of oil, water, surfactant and cosurfactants that offered stimulating perspectives in various applications. The purpose of these study was to create a microemulsion using novel amino acid based anionic sodium N-lauroylsarcosinate (SNLS) surfactant for application in personal care formulations. Triglyceride oils such as caprylic acid, oleic acid and carboxylic acid ester isoamyl acetate were used as oil phase, while short chain alcohols like propanol and butanol were used as cosurfactants. The gradual variations happening in the microstructure of the microemulsions were explored via several complementary characterization techniques. Phase diagrams constructed with or without cosurfactants and using different ratio of surfactant/ cosurfactant (Smix) showed that largest microemulsion region was observed only in the presence of cosurfactant and from Smix of 1:1. Solubility of SNLS in pure water is around 30 wt%, which upsurges in presence of propanol or butanol up to around 85 wt%. This leads to increase in microemulsion region in phase diagram with increasing solubility of oils in the SNLS solution. Microemulsions were relatively stable at an ambient temperature of 27 °C. The optical microscopy, electrical conductivity and viscosity measurement were performed to examine the microstructural changes within the microemulsion region. Three different phases such as water in oil (w/o), bicontinuous, and oil in water (o/w) microemulsion were observed. Foaming behavior specifies increased foam stability of SNLS in the presence of certain amount of oils. Dynamic light scattering study supports the well-defined microemulsion stability even after the manifold dilution. The results obtained from this study may have implications for the developments of an appropriate tactic to prepare stable microemulsion from SNLS which could be exceedingly favorable for personal care formulations.