Effects of polymers on particle adsorption on macroscopic surfaces studied by optical reflectometry

The adsorption of nanometer-sized silica particles on a macroscopic silica surface pretreated with different polymers was studied using optical reflectometry in a stagnation point flow cell. Efficient sticking of particles occurs only when no electrostatic repulsion between particles and surface exists. Cationic polyelectrolytes, e.g., partially methylated poly(vinylimidazole), are very efficient in inducing adsorption of negatively charged SiO2 particles. Competition between the negatively charged SiO2 particles and an anionic polymer present in the suspension reduces the amount of particles adsorbed on the surface. Adsorbed nanometer-sized silica particles do not become embedded in the adsorbed polymer layer but rather stay on the periphery of this layer on the time scale of the experiment (15 min). Therefore, repeated sequential addition of adsorbing polymer and particles will lead to controllable high amounts of particles on the surface. (C) 1998 Academic Press.