Article révisé par les pairs
Résumé : The thermodynamics of interfacial dipole layers allows the demonstration of the role of the dielectric constants on the orientation affinity of dipoles at interfaces. A linear dependence of the difference of the affinities with the difference of the reverse mean dielectric constants is evidenced by comparing the orientation affinities of the same dipolar system towards two couples of different fluids. Surface relaxation and co-operative orientation induced by an electromechanical field are also discussed. Experiments performed by L. Lavielle et al. (CNRS Mulhouse) on grafted polyethylene and polypropylene in different liquids show good correlation with the theory. © 1991.