The Unique Self-assembling Behavior of Highly Purified Long Chain Mono Alkyl Phosphate Salt

Abstract

Alkyl phosphates are well known and commonly used for a long time in the cosmetic and detergent field as a mild surfactant. However, many of general industrial products of alkyl phosphate in the market are the mixtures of mono-, di- and tri-esters which do not have the specific features of mono ester. In this study, by increasing the mono alkyl content, we tried to discover the new functional behavior and structure using the highly purified hexadecyl alkyl phosphate.
Among the compounds studied, hexadecyl phosphate neutralized with L-arginine (R16MP-Arg) in an aqueous system showed characteristic solution properties and association behavior below Krafft temperature. Spontaneous swelling of R16MP-Arg was observed below the Krafft temperature, and a gel structures composed of R16MP-Arg and water was formed without heating and shaking. This gel was identified as a thermodynamically stable “α-gel” based on the results of DSC and SAXS measurements.
In this study, we revealed that highly purified mono hexadecyl phosphate with L-arginine organized stable α-gel structure. Cosmetics in which this α-gel is used as the base give a refreshing and smoothing sensation when applied to the skin. The unique property of R16MP-Arg is that it affords a stable gel structure even when mixed with fatty alcohol.