Stimuli‐Driven Control of the Helical Axis of Self‐Organized Soft Helical Superstructures

• Published in: Advanced materials (Weinheim) 2018-06, Vol.30 (25), p.e1706512-n/a
• Main Authors: Bisoyi, Hari Krishna, Bunning, Timothy J., Li, Quan
• Format: Article
• Language: English
• Subjects: beam steering; Cholesteric liquid crystals; Computational fluid dynamics; Control systems; helical axis control; Liquid crystals; Materials science; Mathematical morphology; microdroplets and microshells; Orientation; Photonics; Stimuli; stimuli responsive; Superstructures
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201706512

Supramolecular and macromolecular functional helical superstructures are ubiquitous in nature and display an impressive catalog of intriguing and elegant properties and performances. In materials science, self‐organized soft helical superstructures, i.e., cholesteric liquid crystals (CLCs), serve as model systems toward the understanding of morphology‐ and orientation‐dependent properties of supramolecular dynamic helical architectures and their potential for technological applications. Moreover, most of the fascinating device applications of CLCs are primarily determined by different orientations of the helical axis. Here, the control of the helical axis orientation of CLCs and its dynamic switching in two and three dimensions using different external stimuli are summarized. Electric‐field‐, magnetic‐field‐, and light‐irradiation‐driven orientation control and reorientation of the helical axis of CLCs are described and highlighted. Different techniques and strategies developed to achieve a uniform lying helix structure are explored. Helical axis control in recently developed heliconical cholesteric systems is examined. The control of the helical axis orientation in spherical geometries such as microdroplets and microshells fabricated from these enticing photonic fluids is also explored. Future challenges and opportunities in this exciting area involving anisotropic chiral liquids are then discussed. Controlled manipulation of the helical axis of stimuli‐responsive self‐organized helical superstructures is of paramount importance both for fundamental studies and technological applications. Stimuli‐driven orientation control of the helical axis of cholesteric liquid crystals and its dynamic switching in multiple dimensions are summarized. Helical axis control in chiral microdroplets and microshells, and heliconical cholesteric liquid crystals are also discussed.