In situ and real-time optical investigation of nitrogen plasma treatment of polycarbonate

Polycarbonates are very attractive polymeric materials with extensive applications in optical technology as well as for replacing conventional rigid substrates, such as glass. The use of plasma treatments has been successfully employed for improving their surface properties and increasing adhesion of subsequent functional coatings. The objective of this study is to employ in situ and real-time Fourier transform infrared spectroscopic ellipsometry for a detailed investigation of the effect of nitrogen plasma treatment using a pulsed DC voltage, on the optical properties of polycarbonates. Measurements taken before, during and after plasma treatment showed the formation of a surface overlayer in which macromolecular chain scission takes place. The evolution of the overlayer thickness and its bonding has been investigated in detail. Also, the study of the surface nano-topography of polycarbonates by atomic force microscopy showed that plasma treatment increases the surface roughness.