MODEL OF AGGREGATION OF COLLOIDAL FINE PARTICLES IN THE PRESENCE OF SUPERSIZED POLYMER

A simple model of the process of stabilization and destabilization of fine colloidal suspensions induced by supersized linear polymers has been tested by the direct simulation method. In the model, a single polymer molecule may bind a number of colloidal particles and thus form an aggregate. It is assumed that a simultaneous attachment of a few fine particles to one macromolecule does not necessarily destabilize the suspension. The destabilization of the system (occurring if aggregate sedimentation dominates its diffusion ability) takes place only when the number of the attached particles per macromolecule exceeds the critical value which depends on the polymer coil dimension in the dispersion medium. The model permits interpretation of several experimental observations of the behavior of colloidal sols upon introduction of very high molecular-weight polymers. The simulation results have been compared with the experimental data on the effect of polyacrylamide on the stability of AgI sol.