Use of fluorinated polyurethanes thermally crosslinkable for obtaining coatings having an improved friction coefficient for the dry lubrication of rubbers, plastics, metals, glass, said polyurethanes obtainable from aqueous dispersions of cationic oligourethanes having a molecular weight null9,000, formed by: a) polyisocyanates, having NCO functionality higher than 2, b) bifunctional hydrogenated monomers, c) bifunctional hydroxylated (per)fluoropolyethers, e) monofunctional hydroxyl or carboxylic (per)fluoropoly-ethers or monofunctional hydroxyl (per)fluoroalkanes optionally: d) hydrogenated monomers by which it is possible to insert a crosslinkable chemical function in the oligourethane; dI) hydrogen-active compounds, able to form with the NCO functions thermolabile bonds.