Optical and nanomechanical study of anti-scratch layers on polycarbonate lenses

In recent years, as the optical-electronic industry developed, polymeric materials were gradually increasing in importance. Polycarbonate (PC) is a good candidate for eyewear applications due to its low weight and transparency. In the case of PC lenses, the deposition of anti-scratch (AS) coatings on the polymer surface is essential for the improvement of the mechanical behavior of the lens. In this work, we present a detailed investigation of the optical and nanomechanical properties of a PC based optical lens and coated by an AS coating as a protective overcoat. The study of the effect of the AS coating on the optical response of the PC lens has been performed by the use of Spectroscopic Ellipsometry (SE) in the IR spectral region, where the characteristic features corresponding to the different bonding configuration of the PC lens and the AS coating were studied. Also, the nanomechanical study of the PC lens, before and after the deposition of the AS coating, performed by nanoindentation measurements revealed the significant enhancement of the mechanical response of the AS/PC lens. More specifically, the AS/PC lens is characterized by enhanced values of hardness and elastic modulus. Finally, the use of AS coating has found to lead to a better scratch resistance and to the reduction of the coefficient of friction (mu) of the PC lens. (C) 2004 Elsevier Ltd. All rights reserved.