Chiral heliconical ground state of nanoscale pitch in a nematic liquid crystal of achiral molecular dimers
Dong Chen,Jan H. Porada,Justin B. Hooper,Justin B. Hooper,Arthur Klittnick,Yongqiang Shen,Michael R. Tuchband,Eva Korblova,Dmitry Bedrov,Dmitry Bedrov,David M. Walba,Matthew A. Glaser,Joseph E. Maclennan,Noel A. Clark +13 more
TLDR
Absence of a lamellar X-ray reflection at wavevector q ∼ 2π/d or its harmonics in synchrotron-based scattering experiments indicates that this periodic structure is achieved with no detectable associated modulation of the electron density, and thus has nematic rather than smectic molecular ordering.Abstract:
Freeze-fracture transmission electron microscopy study of the nanoscale structure of the so-called “twist–bend” nematic phase of the cyanobiphenyl (CB) dimer molecule CB(CH2)7CB reveals stripe-textured fracture planes that indicate fluid layers periodically arrayed in the bulk with a spacing of d ∼ 8.3 nm. Fluidity and a rigorously maintained spacing result in long-range-ordered 3D focal conic domains. Absence of a lamellar X-ray reflection at wavevector q ∼ 2π/d or its harmonics in synchrotron-based scattering experiments indicates that this periodic structure is achieved with no detectable associated modulation of the electron density, and thus has nematic rather than smectic molecular ordering. A search for periodic ordering with d ∼ in CB(CH2)7CB using atomistic molecular dynamic computer simulation yields an equilibrium heliconical ground state, exhibiting nematic twist and bend, of the sort first proposed by Meyer, and envisioned in systems of bent molecules by Dozov and Memmer. We measure the director cone angle to be θTB ∼ 25° and the full pitch of the director helix to be pTB ∼ 8.3 nm, a very small value indicating the strong coupling of molecular bend to director bend.read more
Citations
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Light-Driven Liquid Crystalline Materials: From Photo-Induced Phase Transitions and Property Modulations to Applications.
Hari Krishna Bisoyi,Quan Li +1 more
TL;DR: This Review focuses on the developments of light-driven liquid crystalline materials containing photochromic components over the past decade, and the developed materials possess huge potential for applications in optics, photonics, adaptive materials, nanotechnology, etc.
Journal ArticleDOI
Nematic twist-bend phase with nanoscale modulation of molecular orientation
Volodymyr Borshch,Young-Ki Kim,Jie Xiang,Min Gao,Antal Jakli,Vitaly P. Panov,Jagdish K. Vij,Corrie T. Imrie,Maria-Gabriela Tamba,Georg H. Mehl,Oleg D. Lavrentovich +10 more
TL;DR: This work experimentally demonstrates a new nematic order, formed by achiral molecules, in which the director follows an oblique helicoid, maintaining a constant oblique angle with the helix axis and experiencing twist and bend.
Journal ArticleDOI
Nature-Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self-Assembly to DNA Mesophase and Nanocolloids.
TL;DR: An account on the state of the art of emerging chiral liquid crystalline nanostructured materials and their technological applications is provided and a perspective on the future scope, opportunities, and challenges is provided.
Journal ArticleDOI
Twist-bend heliconical chiral nematic liquid crystal phase of an achiral rigid bent-core mesogen.
Dong Chen,Michi Nakata,Renfan Shao,Michael R. Tuchband,Min Shuai,Ute Baumeister,Wolfgang Weissflog,David M. Walba,Matthew A. Glaser,Joseph E. Maclennan,Noel A. Clark +10 more
TL;DR: The chiral, heliconical (twist-bend) nematic ground state is reported in an achiral, rigid, bent-core mesogen (UD68) and exhibits nanoscale, periodic modulation with no associated modulation of the electron density.
Journal ArticleDOI
Understanding the twist-bend nematic phase: the characterisation of 1-(4-cyanobiphenyl-4′-yloxy)-6-(4-cyanobiphenyl-4′-yl)hexane (CB6OCB) and comparison with CB7CB
Daniel A. Paterson,Min Gao,Young-Ki Kim,Afsoon Jamali,Kirsten L. Finley,Beatriz Robles-Hernández,S. Diez-Berart,Josep Salud,M. Rosario de la Fuente,Bakir A. Timimi,Herbert Zimmermann,Cristina Greco,Alberta Ferrarini,John Storey,David López,Oleg D. Lavrentovich,Geoffrey R. Luckhurst,Corrie T. Imrie +17 more
TL;DR: A complementary extended molecular field theory was found to be in suggestive accord with the (2)H-NMR studies of CB6OCB-d2, and those already known for CB7CB-d4, including the reduced transition temperature, TNTBN/TNI, and the order parameter of the mesogenic arms in the N phase close to the NTB-N transition.
References
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