This paper describes the use of spectroscopic ellipsometry to investigate the adsorption process of model polyelectrolytes (PDDAC and PSS) to thin-films of PDMS. A description of the information collected by ellipsometry as well as complementary information obtained by atomic forcemicroscopy and contact anglemeasurements is discussed. Upon identification of the driving forces and optimum experimental conditions required for the adsorption, multilayer constructs were fabricated (ranging from 1 to 20 nm in thickness) and used to evaluate their effect on the separation of phenolic compounds by capillary electrophoresis. According to the presented results, polyelectrolyte layers of approximately 10 nm thick provided the best conditions for the separation of the selected phenolic compounds.