CHARACTERIZATION OF THE BRUSH REGIME FOR GRAFTED POLYMER LAYERS AT THE SOLID-LIQUID INTERFACE

Using small-angle neutron-scattering techniques, the scaling laws between the thickness of a grafted polymer layer h, its graft density sigma, and the molecular weight of the grafted chains M have been determined for polydimethylsiloxane chains end grafted on porous silica. The observed laws h almost-equal-to M-sigma in bad solvent and h almost-equal-to M-sigma-1/3 in good solvent provide the first experimental evidence of the "brush" regime, where the grafted chains, confined by their neighbors, are stretched normal to the surface.