Spontaneous polarization, tilt angle, hysteresis and low-frequency relaxations in hydrogen bonded chiral liquid crystal dimer: M*SA:9OBA

2019 ◽  
Vol 551 (1) ◽  
pp. 178-196
Author(s):  
Mosalikanti Surekha ◽  
Attaluri Venkata Naga Ashok Kumar ◽  
Pallavajhula Venkata Chalapathy ◽  
Dakshina Murthy Potukuchi
Keyword(s):  
Liquid Crystal ◽  
Tilt Angle ◽  
Spontaneous Polarization ◽  
Low Frequency ◽  
Chiral Liquid Crystal ◽  
Hydrogen Bonded

Design, Synthesis and Characterization of Hydrogen Bonded Binary Liquid Crystal Complex from 4-Methoxycinnamic Acid and 4-Hexyloxybenzoic Acid (4MCA:6OBA)

2017 ◽  
Vol 231 (11-12) ◽  
Author(s):  
Thamilarasan Ranjeeth Kumar ◽  
Sankaran Sundaram ◽  
Thangaiyan Chitravel ◽  
Ramasamy Jayaprakasam ◽  
Vellalapalayam Nallagounder Vijayakumar
Keyword(s):  
Liquid Crystal ◽  
Binary Mixture ◽  
Tilt Angle ◽  
Phase Variation ◽  
Optical Microscope ◽  
Scanning Calorimetry ◽  
Smectic C ◽  
Ir Studies ◽  
Methoxycinnamic Acid ◽  
Hydrogen Bonded

AbstractHydrogen bonded liquid crystal (HBLC) binary mixture has been synthesized from mesogenic 4-methoxycinnamic acid (4MCA) and mesogenic 4-hexyloxybenzoic acid (6OBA) with different mole ratio. The mesomorphic phase behavior and corresponding phase transition temperatures along with the enthalpy values were investigated by differential scanning calorimetry (DSC). The characteristic textures of 4MCA+6OBA binary mixture were observed by using polarizing optical microscope (POM). Fourier transform infrared spectroscopic (FT-IR) studies confirm the formation of hydrogen bond in the present binary mixture. A note worthy observation in this complex is that pure mesogens have no smectic phase where as 4MCA+6OBA binary mixture exhibits a nematic phase along with higher order smectic C (Sm C) phase. Variation of mole ratio influences thermal properties such as phase peak, enthalpy values and thermal span width of the present HBLC binary mixture complex. The optical tilt angle of 4MCA+6OBA for smectic C phase and thermal stability factors have been investigated. Optical tilt angle for smectic C phase is determined and same is fitted to a power law.

Low frequency dielectric spectroscopy of two room temperature chiral liquid crystal mixtures

2003 ◽  
Vol 76 (11) ◽  
pp. 945-958 ◽  
Author(s):  
M.B. Pandey ◽  
R. Dhar ◽  
K. Agrawal ◽  
R.P. Khare ◽  
R. Dabrowski
Keyword(s):  
Liquid Crystal ◽  
Dielectric Spectroscopy ◽  
Room Temperature ◽  
Low Frequency ◽  
Chiral Liquid Crystal

Attractive mode force microscopy of chiral liquid crystal surfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 268-269
Author(s):  
B.D. Terris ◽  
R. J. Twieg ◽  
C. Nguyen ◽  
G. Sigaud ◽  
H. T. Nguyen
Keyword(s):  
Liquid Crystal ◽  
Crystal Surfaces ◽  
Free Surfaces ◽  
Control Range ◽  
Force Microscopy ◽  
Liquid Crystal Films ◽  
Chiral Liquid Crystal ◽  
Crystal Films ◽  
Electrostatic Charging ◽  
And Shifts

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.

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