Adhesion of ZnO and Al2O3 Coatings on Polycarbonate

Zinc oxide coatings were deposited on polycarbonate (PC) films by sputtering of ZnO target in Ar:O-2 atmosphere in order to protect this polymer against photodegradation. The adhesion of the deposited layers depends on the deposition conditions and the substrate properties. PC was treated by various cold plasmas in order to increase its surface energy. Wettability measurements revealed that a CO2 plasma treatment of short duration induces a high increase of the polar component of the energy. XPS analyses showed that this is due to a functionalisation of PC, mainly by creation of C=O bonds. ZnO was deposited either directly or with an alumina sublayer to prevent the ZnO photocatalytic effect on the PC surface. XPS analyses of PC/ceramic interfaces suggested that chemical bonding can take place between the two materials brought together.