Dissipative particle dynamics simulation of grafted polymer brushes under shear

Abstract

The dissipative particle dynamics technique has been used to study grafted polymer chains under shear in solvents of different quality. We show that width of the grafted polymer chains decreases with increasing shear rate for an adsorbed monolayer and bilayer in an athermal solvent but that the layer shrinks in a poor solvent and there is no further decrease in the width on shearing. The polymer chains are preferentially aligned along the direction of the shear and tilted away from the surface normal with even the smallest shear rates. The orientational ordering with respect to the layer director increases with increasing shear. Reducing the quality of the solvent dramatically reduces the width of the grafted layers and the friction between them.