Photorefractive behaviors in a polymer composite including layered silicates

Abstract

Photorefractive (PR) behavior was observed in a polymer nanocomposite system. The composite is made up of poly(N-vinylcarbazole) (PVK), 2,4,7-trinitro-9-fluorenone (TNF), 4-(4-nitrophenylazo)aniline (DO3), and 9-ethylcarbazole (ECZ), with or without Montmorillonite (MMT) or laponite as a layered silicate. The structures of nanocomposite-PR samples were investigated by X-ray diffraction (XRD). To investigate the PR property, two-beam coupling (TBC) and four-wave mixing experiments were performed. The gain coefficients of the MMT-based nanocomposite-PR system are somewhat lower than that of the unfilled system. However, the equilibrium normalized final diffracted signal of PR-nanocomposite is higher than the unfilled PR sample. Furthermore, by adding laponite instead of MMT to the polymeric PR system, the gain coefficient increases to the original value of the unfilled system by reducing the light scattering, so that it can be said that the memory stability is greatly enhanced in grating decay behavior. (C) 2002 Elsevier Science B.V. All rights reserved.