Web Release Date: January 24,
Superior Photochromic Performance of Naphthopyrans in a Rigid Host Matrix Using Polymer Conjugation: Fast, Dark, and Tunable
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CSIRO Molecular & Health Technologies, Bag 10, Clayton VIC 3169 Australia, Centre of Advance Macromolecular Design, School of Chemical Sciences and Engineering and School of Chemical Sciences and Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia, and The Cooperative Research Centre for Polymers, 8 Redwood Drive, Notting Hill, VIC 3168, Australia
Received August 8, 2007
Revised Manuscript Received December 3, 2007
Abstract:
The attachment of low Tg poly(n-butyl acrylate) polymers (Mn 4100 to 13 100) to naphthopyran photochromic dyes provided large tunable improvements in their photochromic performance in a rigid thermoset host polymer matrix. Both coloration and decoloration speeds were greatly increased, with the critical t1/2 decoloration times reduced by 50-95% and t3/4 decoloration times reduced by at least 63% through the use of these polymer conjugates. In addition, the optical density of the colored form of the dye-polymer conjugates rapidly reached a steady state absorption ca. 60-70% greater than the nonpolymer conjugated control dyes. The effect of the geometry of the polymer conjugates was examined, and it was found that mid-placement of the dye on the polymer provided secondary decoloration speed enhancement over end-placement. Thus, conjugation of low Tg poly(n-butyl acrylate) not only provides faster coloration and decoloration but also greatly increases optical density with near square-wave characteristics.
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