Study of the Fatigue Process and the Yellowing of Polymeric Films Containing Spirooxazine Photochromic Compounds

Article abstract of DOI:10.1246/bcsj.68.1220

Photochromic polyurethane films containing 5-substituted 1,3-dihydro-3,3-dimethyl-1-alkylspiro<2H-indole-2,3'-<3H>pyrido<3,2-f><1,4>benzoxazine> and 1,3-dihydro-1,3,3-trimethylspiro<2H-indole-2,3'-<3H>naphth<2,1-b><1,4>oxazine> were degraded under xenon light exposure.The loss of the photochromic response was monitored by spectrophotometry as a function of the irradiation time; meanwhile, the photoproduct formation and the amount of photochromic material still available were analyzed by chromatography after liquid-solid extraction.At the same time, the fade rateswere monitored after flash-excitation photolysis or after the photostationary state during degradation.It was clearly demonstrated that the loss of photochromism was due exclusively to a photooxidation process of the initial dye, and not to an acceleration of the bleaching or a potential screen effect caused by the photoproducts.