Effect of heat treatment and additives on the photochromic and mechanical properties of sol-gel derived photochromic coatings containing spirooxazine

Abstract

The experimental results on the photochromic and mechanical properties of coatings containing 1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3''(3H)-naphth(2,1-b)(1,4) oxazine] (SO) derived from 3-glycidyl-oxypropyltrimethoxysilane (GPTMS), bisphenol A (BPA) and 1-methylimidazole (MI) by sol-gel processing are presented. It is shown that heat treatment temperature is a conflicting factor to the photochromic intensity (ΔA0), photostability and abrasion resistance of the photochromic coatings. With increasing densification temperature the matrix rigidity increases leading to a decrease of ΔA0 and at the same time an enhancement of both abrasion resistance and photostability, the optimum heat treatment temperature is 110'°C under our experimental conditions. By the use of certain additives, e.g., fluorosilanes (FAS), not only ΔA0 but also the photostability and the abrasion resistance of the photochromic coatings have been further improved.