Using Polymer–Surfactant Charge Ratio to Control Synergistic Flocculation of Anionic Particulate Dispersions

Abstract

This study investigates the flocculation induced destabilization of particulate dispersions by oppositely charged polymer–surfactant complexes, with a particular focus on controlling interactions by modulating the charge ratio Z, (where Z = [+polymer]/[−surfactant]) via [−surfactant] at fixed Cpolymer. Cationic hydroxyethyl cellulose (cat-HEC) polymer-sodium dodecylsulfate (SDS) complexes were prepared with either excess polymer (Z > 1) or surfactant (Z Z > 1, leaving any excess particle surfaces uncoated after gentle centrifugation. However, complexes with Z 12E6) showed no additional destabilization of the dispersions, but post-centrifugation relaxation rates indicated preferential adsorption of C12E6 onto the particle surfaces. Since the dominant forces are electrostatic, this study highlights the possibility of controlling the interactions between oppositely charged polymer–surfactant complexes and particle surfaces by modulating Z through [−surfactant].

Keywords

• solvent relaxation NMR
• polymer–surfactant interactions
• phase separation
• adsorption