Controlling molecular mobility in polymer matrices: synchronizing switching speeds of multiple photochromic dyes

We report a method that allows the facile synchronization of multiple photochromic dyes in a rigid polymer lens matrix together with large increases in their switching speeds. This was achieved by simple chromatographic fractionation of dye-poly(dimethylsiloxane) (PDMS) conjugates to provide tunable switching speeds with longer PDMS tails providing faster switching speeds and shorter tails providing slower switching with no effect on the electronic nature of the dyes. This was done for mono end-functional dye-PDMS conjugates (one dye at one end of the PDMS) and new telechelic dye-PDMS conjugates (one dye at each end of a PDMS oligomer) using a wide variety of academic and commercially important spirooxazines and naphthopyrans (chromenes). Telechelic conjugates gave faster fade performance per unit length of PDMS oligomer (greater atom efficiency) while having superior matrix compatibility. Independent photochromic switching of different photochromic dye-PDMS conjugates within the same lens matrix was demonstrated, resulting in the ability to synchronize coloration and decoloration within multidye systems. The utility of the method was shown by the creation of a neutral colored (gray) lens, produced through the combination of three different colored dye-PDMS conjugates having similar independent fade speed kinetics, and showed exceptional fade performance with good hue maintenance compared to the control lens.