Improving the optical properties of vinyl-functionalized silica colloidal crystals by thermal annealing

概要

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Three-dimensional vinyl-functionalized silica colloidal crystals (VFS-CCs), which the attenuation of the photonic bandgap could be significantly improved by thermal annealing, were fabricated by a gravity sedimentation process using monodisperse vinyl-functionalized silica spheres. With the increase of the annealing temperature from 60 to 140°C, the attenuation of the bandgap had more than 40% increase. The SEM images and optical UV–vis–NIR spectra confirmed the high quality of the VFS-CCs. Fourier transform infrared (FT–IR) spectra and thermo-gravimetric analysis (TGA) of the vinyl-functionalized silica spheres demonstrated that the optimal annealing temperature of the VFS-CCs was about 120°C, slightly lower than the oxidation temperature of the vinyl groups. This work provides a simple and controllable method for fabricating and optimizing the optical properties of the surface-modified colloidal crystals.