Enhancement of the Photochromic Performance of Spirooxazine in Sol-Gel Derived Organic-Inorganic Hybrid Matrices by Additives

Organic-inorganic hybrid materials synthesized via sol-gel processing are excellent solid matrices for photochromic dyes like spirooxazine, and the photochromic performance can be further enhanced by introducing suitable additives. This work describes the effects of additives on the photochromic intensity (Δ A0), decolouration rate (k) and photostability of spirooxazine in sol-gel derived organic-inorganic hybrid matrices. They include fluoro-alkylsilane (FAS), bisphenol A (BPA) and methyl-imidazole (MI). FAS enhances both Δ A0 and photostability, but has little effect on k. The higher the content of BPA, the higher the Δ A0 and the higher the photostability, but the lower the k. The effect of MI on Δ A0 and k is not so considerable as that of BPA and is a little complicated, while significant improvement in photostability is achieved by the addition of MI at an optimum concentration with the presence of BPA at a higher content.