The cause of irregular shape of the photonic crystal fabricated with recycled solvent

Abstract

Managing waste solvent is the most cost effective and environmentally friendly method. To reduce waste solvent, this investigation focused on the effect of the solvent ratio on the diameter of the spheres and on the structure of the photonic crystal by using recycled solvent. The sphere diameter reduced with the reduction of the NH4OH ratio. To investigate the effect of the recycled solvent on the structure of the silica spheres, the recycled solvent was repeatedly used five times. The diameter and shape of the silica spheres were similar when the solvent was used twice. However, the shape and structure of the spheres became more irregular with the increase of the recycling time. The FTIR spectra of all spheres are identical. To identify the cause of the irregular structure of the spheres, the solvent recycled five times was evaporated, and the residual compound was analyzed. As a result, the residual compound was composed of Si-O-Si and Si-OH. This residual silica compound may cause the connected and irregular structure of the spheres.