Effect of surfactant on reaction-limited aggregation kinetics of polymer colloids
Advancing the chemical engineering fundamentals
Interfacial & Colloidal Phenomena - I (T2-6a)
Keywords: aggregation, surfactants, polymer colloids, light scattering
The aggregation under stagnant conditions of polymer colloids has been investigated for many years. A universal behavior has been proposed almost twenty years ago. However, many real-life systems show strong deviations from the expected universal behavior. Despite the large number of experimental and modeling works published in the literature, no entirely satisfactory quantitative description has been provided of these effects. We demonstrate that many of the observed deviation from universalities are caused by the anomalous behavior of surfactants adsorbed on particles. Our experimental results indicate that polymer colloidal systems do follow the universal behavior when no surfactant molecules are adsorbed on the particles surface, and stabilization is only provided by fixed charges. On the other hand, even small amounts of surfactant lead to an anomalous slowdown in aggregation kinetics, which can be quantitatively accounted for when redistribution of surfactant molecules on the particles is considered. This redistribution of surfactant molecules slowly increases the particles and clusters stability during the aggregation process, thus leading to strong changes in evolution of the cluster mass distribution. A model based on population balance equations is used to describe the process. The observed phenomenon opens new possibilities in controlling the aggregation kinetics by simply tuning the amount of the surfactant added to the system.
Presented Wednesday 19, 15:20 to 15:40, in session Interfacial & Colloidal Phenomena - I (T2-6a).
