Optical properties and photo-isomerization processes of PMMA–BDK–MR nanocomposite thin films doped by silica nanoparticles

Abstract

A novel nanocomposite thin films based on azo dye methyl red (MR) hosted in polymethylmethacrylate (PMMA) incorporated with benzyl dimethyl ketal (BDK) as a photo-initiator and doped with 2.5% and 5% of silica NPs are prepared by dip coating technique on fused silica substrates. We investigate the optical, chemical and thermal properties of (PMMA–BDK–MR)/silica NPs nanocomposite thin films by performing UV–Vis spectrometer, Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analyser (TGA). The purpose of inserting the azo dye MR in the composite is to stimulate the nanocomposite to perform the cis ↔ trans cycles through illumination ↔ thermal relaxation for Write/Read/Erase optical data storage and UV-light sensors. Our UV–Vis and FTIR findings confirm the hysteresis cycle of trans- and cis-states. Consequently, (PMMA–BDK–MR)/silica NPs thin films could be successfully used in Write/Read/Erase optical data storage and UV-light sensors. The TGA measurements show that the weight loss of the nanocomposites is reversibly proportional to the silica NPs concentration indicating the reinforcement of physicochemical bonding density as the concentration of silica NPs is increased.