Highly monodisperse vinyl functionalized silica spheres and their self-assembled three-dimensional colloidal photonic crystals

A one-step method was presented for the controlled synthesis of highly monodisperse vinyl functionalized silica spheres (VFSSs), which could be self-assembled into three-dimensional (3D) fcc colloidal photonic crystals on a horizontal glass slide by a gravity sedimentation process. One precursor (vinyltriethoxysilane) and one solvent (water) were used in the experiment. The size of VFSSs could be adjusted from 420 to 650 nm with relative standard deviation below 2% by controlling the dripping speed of diluted ammonia catalyst, without changing the concentration of precursor/catalyst. SEM and TEM images illustrate the copiousness in quantity and the uniformity in size/shape of the VFSSs. 29Si nuclear magnetic resonance (NMR) spectrum confirms the surfaces of VFSSs have abundant vinyl groups (–CHCH2) which connect to the silicon atoms. Optical characterizations of the transmission spectra reveal that the periodic arrays exhibit a photonic band gap in the (1 1 1) direction of the fcc lattice in consistent with the Bragg diffraction theory. This work has also been extended to prepare other monodisperse surface-modified silica spheres and fabricate organic functionalized colloidal templates.