Induction, Fixation and Recovery of Self-Organized Helical Superstructures in Achiral Liquid Crystalline Polymer

Fixation, storage and self-recovery of chiral information in superstructures constructed by weak non-covalent bonds remains a big challenge in nature. Here we describe a novel self-assembled system where the molecular chirality can be transferred and further stored into a helical superstructure. Based on achiral liquid crystalline polymers (LCPs), the twist between azobenzene (Azo) units in polymer side chains can be switched by the configuration or alkyl chain length of the introduced chiral dopant. Furthermore, the cross-linking strategy of polymer side chains was adopted to allow the permanently memorizing the induced helical superstructure after complete removal of chiral dopant. Even the helical superstructure was temporarily destroyed by UV light irradiation, the stored chiral information enabled the self-recovery of the previous helical chirality, without the need of any pre-existing chiral source. The chiral switching in the non-absence of chiral source is unprecedented and open a new window for the design and application of chiral materials.