The use of poly(alkylene oxide)s to achieve fast and controlled photochromic switching in rigid matrices

Abstract

We report a conjugation system for the enhancement of photochromic dye performance in rigid matrices using widely available, cheap, chemically robust and compatible polymeric starting materials, namely poly(propylene oxide) (PPO) and poly(1,2-butylene oxide). Conjugation of these soft (low Tg) polymers to an indeno-fused naphthopyran photochromic dye, in a telechelic geometry, gives access to a wide range of accelerated and tuned fade speeds (decoloration) via variation in molecular weight. The t1/2 and t3/4 fade speeds for PPO conjugates (polymer molecular weights ranging between ca. 425 and 2000) are accelerated by 35–58 and 51–76%, respectively, compared with the nonconjugated control dye. Longer oligomers provide faster decoloration approaching that obtained in solution. The stability of the polyethers allows functionalization using a wide variety of chemistries, including harsh acid catalyzed transformations, providing an overall facile synthesis of photochromic dye-polymer conjugates in high yield and purity. In addition, these polymers give easy access to conjugates with star-type architectures, which provide an even further improvement in performance compared with their linear counterparts with less conjugated polymer needed per dye to achieve a given fade speed. © 2012 Commonwealth of Australia. J Polym Sci Part A: Polym Chem, 2012