Controlling Molecular Mobility in Polymer Matrices: Synchronizing Switching Speeds of Multiple Photochromic Dyes

Abstract

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.

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

“…The result is significantly increased coloration and fade‐speeds (approaching those seen in solution) achieved without compromising the mechanical properties of the host lens matrix. Of the polymers tested, including poly(ethylene glycol)5, 12, 13 and poly( n ‐butyl acrylate),9, 11 we found that conjugation of photochromic dyes to polydimethylsiloxane (PDMS) oligomers was most effective in enhancing fade speed 5–7. As well as being effective, PDMS was also very efficient with fairly short oligomers, ranging from about 6 to 25 siloxane repeat units, providing a large effect.…”

“…We have previously reported a method by which exceptional photochromic switching performance is realized within rigid polymeric matrices 5–11. The covalent attachment of soft, low T g oligomers/polymers directly to photochromic dyes (polymer conjugation) provides a fluid and mobile local environment for relatively unhindered switching to occur.…”

“…As well as being effective, PDMS was also very efficient with fairly short oligomers, ranging from about 6 to 25 siloxane repeat units, providing a large effect. Also, efficiency was greater where a photochromic dye was covalently attached at each end of linear PDMS oligomer (telechelic conjugates) in contrast to mono end‐functionalization 6. Fade speed kinetics could also be tuned with varying the length/molecular weight of the attached oligomer, with faster fading achieved with increasing chain length.…”

2H‐Naphthopyran‐Based Three‐State Systems: From Solution Studies to Photoresponsive Organic/Inorganic Hybrid Materials

“…In this paper, we study 2 H ‐naphtho[1,2‐b]pyrans 5 , 12 , 13 , and especially the neat COOH‐terminated monolayer on Si(111) containing compound 13 as headgroup ( S6 ). These naphthopyrans were chosen because of their two thermally more stable colored open forms (OFs: transoid‐cis (TC) and transoid‐trans (TT)) (Figures , ) in comparison to other naphthopyrans . Moreover, for development of multistate switchable surfaces, they offer the possibility to use UV illumination, thermal relaxation and visible light‐illumination for switching events into several directions.…”

Solvent-dependent fluorescence enhancement and piezochromism of a carbazole-substituted naphthopyran

“…A new absorbance band centered at 467 nm appeared and reached maximum after irradiation of 260 s, which is attributed to the absorbance of open-form CzNP (Scheme 1). The extended π-conjugation and quasi-planar structures of MC forms resulted in the highly colored MC forms [32,33].…”