Untwisting of the helical structure in a plane layer of chiral liquid crystal

JETP Letters ◽  
2002 ◽  
Vol 76 (2) ◽  
pp. 88-92 ◽  
Author(s):  
V. A. Belyakov
Author(s):  
B.D. Terris ◽  
R. J. Twieg ◽  
C. Nguyen ◽  
G. Sigaud ◽  
H. T. Nguyen

We have used a force microscope in the attractive, or noncontact, mode to image a variety of surfaces. In this mode, the microscope tip is oscillated near its resonant frequency and shifts in this frequency due to changes in the surface-tip force gradient are detected. We have used this technique in a variety of applications to polymers, including electrostatic charging, phase separation of ionomer surfaces, and crazing of glassy films.Most recently, we have applied the force microscope to imaging the free surfaces of chiral liquid crystal films. The compounds used (Table 1) have been chosen for their polymorphic variety of fluid mesophases, all of which exist within the temperature control range of our force microscope.


2019 ◽  
Author(s):  
Adam Al-Janabi ◽  
Richard Mandle

<p>The nematic twist-bend (N<sub>TB</sub>) liquid crystal phase possesses a local helical structure with a pitch length of a few nanometres and is the first example of spontaneous symmetry breaking in a fluid system. All known examples of the N­<sub>TB­</sub> phase occur in materials whose constituent mesogenic units are aromatic hydrocarbons. It is not clear if this is due to synthetic convenience or a <i>bona fide</i> structural requirement for a material to exhibit this phase of matter. In this work we demonstrate that materials consisting largely of saturated hydrocarbons could also give rise to this mesophase. Furthermore, replacement of 1,4-disubstituted benzene with <i>trans</i> 1,4-cyclohexane or even 1,4-cubane does not especially alter the transition temperatures of the resulting material nor does it appear to impact upon the heliconical tilt angle, suggesting the local structure of the phase is unperturbed. Calculating the probability distribution of bend angles reveals that the choice of isosteric group has little impact on the overall molecular shape, demonstrating the shape-driven nature of the N<sub>TB</sub> phase. </p>


2021 ◽  
Vol 155 (5) ◽  
pp. 054903
Author(s):  
Jan-Christoph Eichler ◽  
Robert A. Skutnik ◽  
Marco G. Mazza ◽  
Martin Schoen

2013 ◽  
Vol 572 (1) ◽  
pp. 59-65 ◽  
Author(s):  
M. Infusino ◽  
A. De Luca ◽  
F. Ciuchi ◽  
A. Ionescu ◽  
N. Scaramuzza ◽  
...  

2012 ◽  
Vol 116 (15) ◽  
pp. 8678-8687 ◽  
Author(s):  
Daiki Tsuji ◽  
Yoichi Takanishi ◽  
Jun Yamamoto ◽  
Atsushi Yoshizawa

2016 ◽  
Vol 44 (3) ◽  
pp. 526-537 ◽  
Author(s):  
Ying-Gang Jia ◽  
Cong-Cong Luo ◽  
Zhao-Xia Zhu ◽  
Jian-She Hu

2011 ◽  
Vol 547 (1) ◽  
pp. 39/[1729]-45/[1735] ◽  
Author(s):  
M. Rajeswari ◽  
J. Ananthaiah ◽  
R. Dabrowski ◽  
V. S. S. Sastry ◽  
S. Dhara ◽  
...  

2021 ◽  
Vol 22 (21) ◽  
pp. 11980
Author(s):  
Tengfei Miao ◽  
Xiaoxiao Cheng ◽  
Yilin Qian ◽  
Yaling Zhuang ◽  
Wei Zhang

Flexible construction of permanently stored supramolecular chirality with stimulus-responsiveness remains a big challenge. Herein, we describe an efficient method to realize the transfer and storage of chirality in intrinsically achiral films of a side-chain polymeric liquid crystal system by combining chiral doping and cross-linking strategy. Even the helical structure was destroyed by UV light irradiation, the memorized chiral information in the covalent network enabled complete self-recovery of the original chiral superstructure. These results allowed the building of a novel chiroptical switch without any additional chiral source in multiple types of liquid crystal polymers, which may be one of the competitive candidates for use in stimulus-responsive chiro-optical devices.


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