Preparation, surface activity and colloidal properties of the ionic complex of chitosan with hexadecyl-oligo-oxyethylene hemisuccinate

•Chitosan PECs with high surface activity were prepared.•Preparation was performed by salt complexation of chitosan with hexadecyl-oligo-oxyethylene hemisuccinates.•Chitosans of DDA 82% with MW of 83 & 240 kDa were investigated.•Surface activity, rheology and emulsification properties of the PECs were investigated. Chitosan polyelectrolyte complex with high surface activity has been prepared by salt complexation of chitosan with hexadecyl-oligo-oxyethylene hemisuccinate (HOS), an anionic surfactant. Physicochemical properties of chitosan–HOS complex can be explained by unusual structure of HOS which has the polyoxyethylene chain located between the polar carboxyl head group and the hydrophobic alkyl tail. Aqueous solutions of chitosan–HOS complex are structured systems with pronounced thixotropic properties. The effect of content of hydrophobic exchanged groups on the solution properties of chitosan–HOS complex and various factors controlling the stability of oil-in-water emulsions in the presence of chitosan–HOS complex are studied. The synergistic effect of the enhanced emulsifying ability of chitosan–HOS complexes is shown. The study discloses a possibility to produce an effective bio-compatible emulsifier based on chitosan–HOS complex.