Influence of added surfactant on particle flocculation in waterborne polymer-particle systems

Polymer-particle interactions can cause particle flocculation and phase separation problems in waterborne coatings. The problems can be the result of interactions that are either too weak or too strong. It is known by empirical work that addition of surfactants can minimize these problems. In this study, the authors have investigated how different types of surfactants influence the polymer-particle interactions. Both hydrophobic and hydrophilic particles were included in the study, and nonionic, anionic, and cationic surfactants were used. A simple model is suggested that can be used to predict the surfactant concentration needed to stabilize the system. The model considers the cmc (critical micelle concentration) of the surfactant, the adsorption to the polymer, and the adsorption to the particles.