抄録
An effect of polymers having certain ultraviolet absorption groups on the photofading rate of methylene blue has been studied in the solution.
Polymer E was prepared by benzoylation of styrene-p-hydroxystyrene copolymer. Polymer K or polymer having o-hydroxybenzophenone (HBP) in the polymer side-chain was prepared by the Photo-Fries rearrangement of polymer E. Polymer K•1 contains a large fraction of styrene (St) unit and small fractions of HBP and phenyl benzoate (PB) unit, while polymer K•2 contains a small fraction of St unit and a large fractions of HBP and PB unit.
Methylene blue in dioxane-ethanol solution containing the above polymers, HBP and PB was exposed to Xenon-arc lamp, respectively and the photofading rate of the dye was calculated from the changes in the visible absorption spectra of the solutions.
The results obtained are summarized as follows.
(1) The polymer having HBP group acted as a retarder on the photofading rate of the dye more effectively than HBP. Polymer E decreased the photofading rate slightly.
(2) Highly modified polymer, K•2 was found to be most effective in retarding the photofading of the dye. In contrast, slightly modified polymer, K•1 showed an acceleration of the photofading. This acceleration was also observed in the case of polystyrene added to the dye solution.
