Effect of annealing on photochromic performance of (E)‐dicyclopropylmethylene‐(2, 5‐dimethyl‐3‐furylethylidene)‐succinicanhydride doped in polyacrylic acid thin film

The purpose of this paper is to investigate the effect of annealing on photochromic performance of (E)‐dicyclopropylmethylene‐(2, 5‐dimethyl‐3‐furylethylid‐ene)‐succinicanhydride doped in polyacrylic acid thin film.

(E)‐dicyclopropylmethylene‐(2,5‐dimethyl‐3‐furyl‐ethylidene)‐succinic‐anhydride (DMDFS‐E) fulgide doped in polyacrylic acid thin films was prepared. DMDFS‐E fulgide doped in polyacrylic acid thin films was heated at various annealing temperatures. Photocoloration, photobleaching and photochemical fatigue resistance for the desired DMDFS‐E fulgide doped in polyacrylic acid thin films were studied.

Upon irradiation with UV light (366 nm), fulgide DMDFS‐E undergoes a conrotatory ring closure to the pinkish colored closed form C (523 nm). The later color was switched back to the original color when the films were irradiated with white light. The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product DMDFS‐C at its λmax of 523 nm. The first‐order plots of photocoloration reaction showed distinct linear line at different temperatures. The slope of these first‐order lines corresponding to the rate constants k. It was found that for photocoloration reaction, the rate constant of the photocoloration reaction was slower than the photobleaching reaction and both reactions decrease with increasing the annealing temperatures. It was found that there was almost improvement of photochemical fatigue resistance of fulgide DMDFS‐E doped in polyacrylic acid thin film at several of the annealing temperatures.

The results obtained in this work showed that the photochromic properties of DMDFS fulgide E were improved upon annealing the film at 100°C. Therefore, it would be recommended for improvement to apply fulgides as annealed polymer films.