Improved photochromic and fatigue performance of (E)‐dicyclopropylmethylene‐(2,5‐dimethyl‐3‐furylethylidene)‐succinicanhydride doped in polyurethane thin film

Abstract Improved photochromic properties and fatigue performance of (E)‐dicyclopropylmethylene‐(2,5‐dimethyl‐3‐furylethylidene)‐succinicanhydride doped in polyurethane thin film were discussed in this study. Fulgide 1‐E doped in polyurethane polymer films was heated at various annealing temperatures. Upon irradiation with UV light (366 nm), fulgide 1‐E undergoes a conrotatory ring closure to the pink‐colored closed form 1‐C . The latter color was switched back to the original color when the films were irradiated with white light. The kinetics of photocoloration and photobleaching processes was followed spectrophotometrically by monitoring the absorbance of the ring‐closed product 1‐C at its λ max of 525 nm. The first‐order plots of photocoloration reaction show distinct linear line and the slope of which corresponding to the first‐order rate constants k . It was found that for photocoloration reaction, the rate constant of the photocoloration reaction is slower than the photobleaching reaction, and both reactions decrease with increasing the annealing temperatures. It was found that there was almost complete loss of photochemical fatigue resistance of fulgide 1 doped in polyurethane polymer film irrespective of the annealing temperature. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers