Rapid photochromic switching in a rigid polymer matrix using living radical polymerization

Fast switching of a photochromic dye in a rigid host matrix has been achieved without any modification of electronic nature of the photochromic entity. The method utilizes living radical polymerization (atom transfer radical polymerization (ATRP)) to grow a low glass transition temperature (Tg) poly(n-butyl acrylate) polymer from a spirooxazine core, creating a low-T _g environment to cushion the photochromic dye while keeping the bulk matrix rigid. In these systems, decoloration speed of the photochromic (t _1/2) was reduced by 40-75% depending on the molecular weight of the poly(n-butyl acrylate) attached. We have demonstrated with this methodology a controlled tuning of photochromic switching. Coarse and fine tuning can be achieved by adjusting first the choice of polymer and second the molecular weight of the polymer.