KINETICS OF POLYMER ADSORPTION IN STAGNATION POINT FLOW

The kinetics of adsorption of poly(ethylene oxide) from water onto silica in stagnation point flow are studied using a reflectometric technique. It is shown that with reflectometry an absolute and continuous determination of the adsorbed mass per unit area can be obtained. For the stagnation point flow, the maximum rate of mass transfer to the surface is theoretically calculated. This rate is compared to the observed adsorption rate and it is concluded that mass transfer is the rate-determining step up to 75% or more saturation, depending on the molecular weight. Plateau adsorbed amounts obtained are in good agreement with those found by others. The molecular weight dependence of the diffusion constant agrees with scaling theory and the plateau adsorbed mass is in accordance with the theory for polymer adsorption from good solvents. © 1990.