The surface energy and stability of pendent semifluorinated groups (SFG) attached to the surface of PDMS were measured using the JKR technique. SFG, made up of a flexible hydrocarbon segment and a mesogen, i.e., the fluorocarbon segment, combine the low surface energy aspect of a (-CF2-) and (-CF3) surface with a resistance to surface reconstruction. An acid chloride group present on the end of the hydrocarbon segment allowed the SFG eo be covalently attached to the surface of hydrolyzed elastomeric PDMS model networks. Whereas the hydrolyzed PDMS surfaces had surface energies of 1-10 J/m(2) and showed large adhesion hysteresis, the SFG-treated surfaces displayed a minimum adhesion hysteresis and had a surface energy of similar to 14.5 mJ/m(2). This result suggests that in the SFG-modified surfaces both (-CF2-) and (-CF3) groups cover the surface. As the extent of hydrolysis of the PDMS networks increased, the density of attached SFG increased (as shown by XPS results), but the surface energy remained constant. No effect of length of time the networks were kept in contact or the rate of unloading was observed.