The H-1 NMR technique is used to study the behaviour of the poly(ethylene oxide) chains grafted chemically on silica in presence or not of solvent. A noticeable influence of the different physicochemical parameters on the conformation of the grafted macromolecules is evinced. The grafting ratio, the temperature, the solvent can all in well chosen situations modify the configurations of the chains. The macromolecules can lay flat on the surface, or be swollen and spread out. Depending on the conformations the dipolar interactions between monomer detected by NMR are different and inform on the behaviour of the chains. In particular a static contribution also called pseudo-solid effect is measured, which is an indication of the local concentration of segments in the vicinity of the surface. (C) 2003 Published by Elsevier Ltd.