DEFORMATION OF GRAFTED POLYMER LAYERS IN STRONG SHEAR FLOWS

We present a theoretical approach for studying the deformation of graf ted polymer layers in strong shear hows that calculates the deformatio n of grafted chains and the solvent how profile within the layer in a mutually consistent fashion. We illustrate this approach by considerin g the deformation of Alexander-de Gennes brushes in simple shear hows. Our model predicts nonuniform deformation of grafted polymer chains a nd appreciable swelling of brushes for shear rates exceeding tau(-1) s imilar or equal to k(B)T/(eta xi(0)(3)), the characteristic hydrodynam ic relaxation rate of a blob of the unperturbed bursh. An asymptotic s welling of similar to 25% for gamma tau much greater than 1 is predict ed, in accordance with theories of brush response to strong applied ta ngential boundary forces. We briefly compare our results to recent exp eriments and to theories of brush deformation in shear conditions and outline the generalization of our approach to more realistic models of grafted polymer layers and to adsorbed polymer layers in strong hows.