Mechanically assembled monolayers (MAMs) can be employed to adjust the surface density of the initiators and consequently that of molecular gradients prepared on flexible supports. The steepness and the position of the gradient of molecules on a substrate are fine-tuned by a combination of grafting and mechanical manipulation of the films. Planar molecular gradients ranging from several millimeters to several centimeters can thus be fabricated. In addition, the wetting properties of the hydrophobic part of the substrate can be adjusted by altering the chemical nature of the films.