Interaction of sodium lauroyl glutamate and potassium lauroyl hydrolyzed collagen with hydroxypropyl methyl cellulose

Hydroxypropyl methylcellulose (HPMC) was used to increase the viscosity of aqueous solutions of sodium lauroyl glutamate (SLG) and potassium lauroyl hydrolyzed collagen (KLHC), as viscosity modifiers commonly used in toiletry products fail to thicken in the presence of these surfactants. A surfactant-polymer link was indicated by a change of surface tension as a function of surfactant and polymer concentration and by viscosity trends of surfactant-polymer mixtures around critical micellar concentration (CMC). A positive surfactant-polymer interaction was suggested by an experimental design of Doehlert. Such an interaction affects the viscosity of the system and the solubility of two lipophilic dyes in the micellar core of the surfactant-polymer complexes. Hydroxypropyl methylcellulose prevents SLG precipitation by lowering its Kraft point.