Preparation and photochromic properties of dye-doped aluminosilicate ORMOCER gels and coatings

Abstract

Aluminosilicate and ORMOCER gels and coatings containing photochromic dyes, 1, 3-dihydro-1, 3, 3-trimethylspiro-[2H-indole-2, 3'-[3H]-naphth-[2, 1-b][1, 4]-oxazine] (SO) and 1', 8a'-dihydro-2', 3'-dimethoxycarbonyl-spiro [fluorene-9, 1'-indolizine] (DHI), were prepared by the sol-gel method and the photochromic activity was monitored in the course of the sol-wetgel-xerogel transformation. The photochromic activity of the aluminosilicate gels decreases rapidly and even vanishes in the wetgel-xerogel stage while that of ORMOCER gels and coatings levels off in the early wetgel-xerogel stage at a reasonably high photochromic intensity with the colour-fading speed similar to that in ethanol and the photostability being considerably improved. The experimental results are discussed in terms of the matrix effect on photochromism of organic dyes.