Effect of nanoclay on optical properties of PLA/clay composite films

This article reports the modification of optical properties of biodegradable/biocompatible polylactide (PLA) using organically modified montmorillonite (OMMT) for microcantilever applications. PLA/OMMT composite films with various OMMT loadings (3, 5 and 7 wt%) were prepared using solvent casting. The surface morphology of the PLA/OMMT composites was examined using scanning electron and atomic force microscopes. The morphological results indicated that the surface roughness increases as a function of the clay loading. The optical properties of the PLA/OMMT composites were studied using variable angle spectroscopic ellipsometry (VASE) and ultra-violet (UV-Vis) spectroscopy. VASE revealed that the refractive index and extinction coefficient (n and k) positively correlated with the thickness of the film. UV-Vis spectroscopy also demonstrated that the absorption of light by PLA/OMMT composite films positively correlated with the clay content in the visible range of the electromagnetic spectrum. To enhance the reflectivity, PLA/OMMT films were coated with a gold layer.