Fast switching immobilized photochromic dyes

A novel photochromic dye conjugate architecture is described, which allows both covalent tethering to a polymeric host matrix and fast photochromic switching. The new conjugates consist of a photochromic dye covalently bound to two different substituents via a Y‐branching linker (hetero Y‐branching), one being a polymerizable methacrylate moiety and the other a soft (low T g ) poly(dimethylsiloxane) oligomer. The novel conjugates gave faster photochromic decoloration in the host lens matrix compared with the electronically equivalent nonmatrix‐bound and unconjugated parent control dyes. In addition, further acceleration of fade speed kinetics was observed with a longer linker between photochromic dye and methacrylate moiety.