ADSORPTION AND DESORPTION OF POLYSTYRENE FROM DILUTE-SOLUTIONS IN SHEAR AND ELONGATIONAL FLOW

The influence of flow on the adsorption and desorption of high molecular weight polystyrene on chromium was studied by ellipsometry for two solution conditions, in decalin at 22-degrees-C (a slightly good solvent) and in cyclohexane at 35-degrees-C (a THETA solvent). Measurements of layer thickness, after collapse induced by solvent removal, provided adsorption levels (mass/area) in both shear (0 < gamma < 1000 s-1) and biaxial elongation (0 < epsilon < 25000 s-1). With decalin the different flow environments had little influence on either adsorption or desorption processes; with cyclohexane a greater impact was noted, although only during adsorption. It appears that flow only affects the adsorption level of a weakly attached subfraction of the bound-chain population.