Abstract: The systems of sodium lauroyl sarcosinate (LS) mixed with nonionic,anionic,and zwitterionic surfactants were studied.By changing the amount and the mixing ratios of these surfactants,it was found that,as for binary systems,synergistic thickening could be achieved by adding a small amount of alkyl polyglucoside (APG).In ternary systems,the mixing ratios of surfactants had significant influences on viscosity,and a self-thickening system of LS/cocamidopropyl betaine (CAB)/APG could be obtained.The viscosity of the mixture was no less than 3 000 mPa·s when the mass of CAB was not lower than LS.The popular silicone- and sulfate-free shampoos can use this self-thickening formulation as a reference.

Key words: surfactant, sodium lauroyl sarcosinate, self-thickening, silicone- and sulfate-free