Abstract: A method for treating the surface of a polymeric substrate, including the following steps: providing a first polymeric substrate; contracting at least one part of one face of the first substrate with some liquid solvent system, the liquid solvent system containing at least a first volatile compound and at least a second compound having a low molecular weight and able to swell and/or soften the polymeric material forming the face; letting at least the volatile compound to evaporate from the face of the first substrate and; contacting the so-treated face of first substrate with a third material.