The influence of hydrocarbon, fluorinated and silicone surfactants on the adsorption, stability and electrokinetic properties of the κ-carrageenan/alumina system

Abstract

Over recent years, the use and development of surfactants and biopolymers has been increased. The interactions between oppositely charged polymers and surfactants lead to the formation of the polymer-surfactant complexes. In this work we focused on studying if different types of cationic surfactants such as hydrocarbon, fluorinated and silicone ones can interact with natural polysaccharide - κ-carrageenan. The conducted tensiometric studies have proven that carrageenan forms the complexes with all of the studied surfactants. In the following part we have studied if and how the pre-formed complexes adsorb on the alumina surface. The conducted adsorption experiments indicated that the polymer-surfactant complexes adsorb on the alumina surface via polymer part, and that the process is governed by the electrostatic and non-electrostatic interactions. The results show that the adsorption of carrageenan increased in the presence of the studied surfactants, likewise the adsorption of the surfactants increased in the presence of carrageenan. Moreover, the influence of the hydrocarbon, fluorinated and silicone surfactants on stability and the zeta potential of the carrageenan/alumina suspensions were studied. The addition of carrageenan to the alumina suspensions leads to the increased stability due to the combination of the electrosteric and depletion stabilizations, whereas the presence of surfactants influenced stability only to a small extent. The obtained results have important implications for stabilization of colloidal systems and preparation of different functionalized materials. The findings of our research are very important in the field of preparation of different colloidal dispersions such as cosmetics, pharmaceuticals, and other useful (bio-)materials.