Characterisation of the optical properties of thin polymer films for their application in detection of volatile organic compounds

The interaction of polymers with volatile organic compounds is widely used in sensor applications. Interaction with an analyte changes the optical properties of polymer films. We investigated two commercially available (poly)siloxanes and one (poly)urethane in contact with tetrachloroethene, toluene and cyclohexane vapours. The refractive index of the polymers and the changes in the physical thickness are separately determined by spectroscopic ellipsometry. The information obtained is used to optimise the sensitive layers with respect to sensitivity and selectivity. With the information obtained the most selective polymers can be chosen for every application.