PHOTOCHEMISTRY AND MULTIPLE HOLOGRAPHICAL RECORDING IN POLYMERS WITH PHOTOCHROMIC PHENOXY-NAPHTHACENE-QUINONE SIDE-GROUPS

The photochromism of phenoxy-naphthacene-quinones in solution was investigated and compared with that of polymers in which one of these compounds was incorporated as a side group, through flexible (CH2)(n) spacers of various lengths. The polymers studied were polystyrene (PS), poly(methyl methacrylate) (PMMA), and polysiloxane (PSX). Up to 90% photochrome side groups could be incorporated in some of these polymers. The polymers were studied both in solution and as flexible films. The quantum yields in solutions of one of phenoxy-quinones was about 0.6 for trans-->ana, and about 0.10 for ana-->trans. The photoconversion trans-->ana is only slightly slowed down in solutions of the polymers, but much more so in films. The rates of photoconversion observed in films, relative to a solution of the photochrome proper were as follows: PS, 12; PMMA, 25; PSX, 50; solution, 100. These rates vary slightly with the concentration of the photochrome but increase with increasing spacer length in PMMA and decrease in PSX. The glass transition temperature may play an important role. Multiple holographic recording on the polymers was investigated.