T. Kakishita et al., EFFECT OF MOLECULAR-ORIENTATION IN MATRIX ON THE PHOTOCHROMISM OF 9' SUBSTITUTED SPIRONAPHTHOXAZINES, Kobunshi ronbunshu, 51(1), 1994, pp. 35-42
As photochromic agents, 1,3,3-trimethylspiro (indoline-2,3' [3 H] naph
tho [2,1-b] [1,4] oxazine) (TM-SNO) and its 9'-substituted spironaphth
oxazine derivatives were doped in poly(methyl methacrylate) (PMMA) fil
ms by solution casting. Effect of molecular orientation of PMMA films
stretched at various ratios on the color decay kinetics of the photoch
romic agents after UV irradiation was investigated. Colorless PMMA fil
ms containing the spironaphthoxazines developed a blue color having an
absorption maximum at about 600 nm, after UV irradiation with a 100 W
high pressure mercury lamp for 60s. In the dark at room temperature,
the color decay of 9'-hexafluoropropene substituted spironaphthoxazine
(TM-Rf-SNO) proceeded slower than the others. However, the reciprocal
of the absorbance at the peak was proportional to time, in all of the
color decay processes. The color decay rate was evaluated by the slop
e (k) as a parameter. The k value increased with increasing stretch ra
tio in different types of stretching. These results were interpreted i
n terms of polymer entanglement by stretching.