THE SCATTERING BY GRAFTED POLYMERS

We have used small angle neutron scattering and the method of contrast variation to study the structure of layers of poly(dimethylsiloxane) terminally grafted on porous silica. We review the main results that we have obtained by varying the polymer molecular weight, the grafting density and the solvent quality. The grafting density depends mainly on the concentration in the reaction bath. At high grafting density and in a good solvent, the chains are stretched and have the same local structure as in bulk semi-dilute solutions of equivalent concentration; furthermore the thickness of the layers is proportional to the polymer molecular weight as predicted by S. Alexander more than ten years ago.