Combined effects of polymer/surfactant mixtures on dynamic interfacial properties

Abstract

AbstractThe present study investigated dynamic interfacial properties of similarly charged and oppositely charged polymer/surfactant mixtures at the oil–water interface. Partially hydrolyzed polyacrylamide (HPAM), sodium dodecylbenzenesulfonate (SDBS), and dodecyltrimethylammonium bromide (DTAB) were used to prepare polymer/surfactant mixtures. The effects of the molecular weight and concentration of the polymer, surface charge and concentration of the surfactant, pH, and ionic strength on the interfacial behavior of polymer/surfactant mixtures at the interface have been investigated. HPAM‐1 exhibited a higher interfacial activity than HPAM‐2. Strong binding interactions were observed between anionic HPAM and cationic DTAB. HPAM had a strong tendency to form more hydrophobic and interfacial activity complexes with DTAB. These complexes could remarkably affect the interfacial properties of polymer/surfactant mixtures at the interface. The adsorption kinetics of polymer/surfactant mixtures were controlled not only by the diffusion occurring between the bulk phase and the interface but also by the energetic and steric barriers generated by the electrostatic interactions and already formed adsorption layers. In addition, the dilational viscoelasticity of polymer/surfactant mixtures was significantly affected by the pH and ionic strength. The HPAM/DTAB mixtures with the addition of salts have higher E values than those of salt‐free systems and HPAM/SDBS mixtures. Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.