Photochromic thermal bleaching kinetics

Figure 40.12 Thermal bleaching kinetics of the photochromic molecules (a) in phenyl-modified matrices (SiO-Ph) and (b) in samples SiO-R7o%, where R is iBu, Ph, and Me.

Pottier, E., Du Best, R., GugHehnetti, R.J., Taridieu, P., Kellmann, A., Tfibel, E, Lenoir, P., and Aubard, J., Substituent, heteroatom and solvent effects on the thermal-bleaching kinetics and absorption spectra of photomerocyanines issued from spiro(indoline-oxazines), Helv. Chim. Acta, 73, 303, 1990 Hori, T., Tagaya, H., Nagaoka, T, Kadokawa, J., and Chia, K., Photochromism of sulfonated spiropyran in a silica matrix, Appl. Surf. ScL, 121/122, 530,1997. 

These compounds were extracted by refluxing the aged photochromic PU films. A kinetic analysis of the thermal bleaching of merocyanine in PU showed that, at variance with that was observed in toluene solution, no acceleration of the ring closure rate took place. The decoloration was described by a biexponential function ... 

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