Figure 6.

(a) Optical images of consecutive light-induced color switches on a photochromic PP membrane according to the transformation of isomeric structures of ring-closed SP to the zwitterionic open form of MC. In areas covered by different masks, light pink PMA–SP brushes do not switch in color, whereas in areas exposed to UV light, the membrane appears deep purple because of PMA–MC brushes. (b) Transmission spectra of thick PMA–SP brushes on a PP film, upon exposure to visible (PMA–SP) and UV (PMA–MC) light, showing the reversible switch in absorption around 570 nm.