Chiroptical Smart Paints: Polymerization of Helical Structures in Cholesteric Liquid Crystal Films

Using polymerizable cholesteric liquid crystal (CLC) paints, we prepare circularly polarized freestanding films that enable students to acquire a basic understanding of circular polarization and molecular chirality. The polymerized helical structures of CLC films can exhibit brilliant structural colors by selective reflection of visible light corresponding to their helical pitch. For the fabrication of freestanding and circularly polarizing films of various colors and shapes, students control helical pitch with the amount of chiral dopants and stabilize them by photopolymerization. On the basis of an understanding of the circularly polarized reflection of CLC paints, students can encode secret letters that are visible only with a specific circular polarizer.