Study of interaction between chitosan and sodium lauryl ether sulfate

Chitosan is a biopolymer that has many potential applications in the industry because of its unique physicochemical properties. Many of these properties depend on its ability to interact with surfactants. The purpose of this study was to investigate interactions between chitosan (Ch), a cationic polysaccharide, and sodium lauryl ether sulfate (SLES), an anionic surfactant with ethylene oxide groups in the polar part of the molecule, in aqueous solution. Changes in the Ch/SLES mixtures were monitored by turbidity, surface tension, electrophoretic mobility, and viscosity measurements. Obtained results show that electrostatic interactions that occur at low SLES concentrations were less pronounced than hydrophobic. The region of hydrophobic interactions was linearly dependent on the concentration of the polymer, so that it ends at Ch/SLES mass ratio 1:3 by forming neutral complexes, which were completely precipitated as a coacervate phase. The research also demonstrates that small variations in structure of anionic surfactant (SDS and SLES) can lead to significant differences in interactions with cationic polymer-chitosan.