Adsorption of poly(diallyldimethylammonium chloride)—sodium methyl-cocoyl-taurate complexes onto solid surfaces

Abstract

The study of the adsorption of supramolecular complexes formed by a highly charged cationic homopolymer (poly(diallyldimethylammonium chloride), PDADMAC), and a sulfate-free anionic surfactant, sodium methyl cocoyl taurate (SMCT), on liquid/solid interfaces was performed by dissipative quartz crystal microbalance, ellipsometry and atomic force microscopy. Moreover, turbidimetry, dynamic light scattering and ζ-potential measurements were carried out to characterize the bulk solutions. The complexes adsorb onto the solid surfaces, leading to inhomogeneous films formed by isolated aggregates randomly distributed through the surface. Additionally, the adsorption kinetics of the bulk complexes onto the negatively charged surface was studied. This work aims to understand the physico—chemical mechanisms involved in the adsorption of polycation—negatively charged surfactant mixtures, interesting for the design of conditioner cosmetic formulations, onto negatively charged surfaces. It is expected that the results here obtained may provide a better understanding of the conditioning effect of cosmetic products on keratinic (hair) substrates.