Interfacial properties of novel surfactants based on maleic and succinic acid for potential application in personal care

Hemiesters and Hemiamides of maleic and succinic acid viz. sodium lauryl succinate (C12SE), sodium lauryl maleate (C12ME), sodium lauryl succinamide (C12SA), sodium lauryl maleamide (C12MA), sodium hexadecyl succinate (C16SE) and sodium hexadecyl maleate (C16ME) were synthesized and investigated as surfactants in the pure water and aqueous hydrotrope [sodium p-toluene sulfonate (NaPTs)] solution. The chemical structures of the prepared surfactants were established by FTIR and 1H NMR spectroscopy. The surface tension measurements depicted low CMC and a high adsorption efficiency (pC20) which is highly beneficial for creating personal care formulations. The dynamic light scattering (DLS) technique indicated the formation of larger micelles which was important for skin care as larger micelles cannot penetrate the skin layer. Moreover, these surfactants depicted good foamability and stability attributed to faster monomer adsorption and small bubble size which was preferred for cleansing application. Additionally, low protein/lipid solubilization by these surfactants indicated its mild behaviour on skin as compared to other commonly used conventional anionic [sodium lauryl sulfate (SLS)], zwitterionic [cocamidopropyl betaine (CAPB)] and nonionic [decyl glucoside (DG)] surfactants. Viscosity measurements suggested decent thickening ability of surfactants in the presence of co-surfactant like lauramine oxide. Basis of all the properties discussed, these novel hemiesters and hemiamides seem promising as surfactants for improving various characteristics in potential personal care formulations.