Non-classical Temperature-dependent Phase Sequence: Long-lived Metastable Piezoelectric Helical Columnar Liquid Crystalline Polymorph

2021 ◽  
Author(s):  
Manh Linh Nguyen ◽  
Jaeduk Byun ◽  
Tae Joo Shin ◽  
Byoung-Ki Cho
Keyword(s):  
Liquid Crystalline ◽  
Research Topic ◽  
Polymorphic Behavior ◽  
Temperature Dependent ◽  
Naphthalene Derivative ◽  
Phase Sequence ◽  
Single Material

Polymorphism is an intriguing research topic, because multiple functionalities can be accessed from a single material. Herein, we report the unusual polymorphic behavior of a liquid crystalline (LC) naphthalene derivative...

STUDY OF MOLECULAR MOTIONS IN TWO LIQUID CRYSTAL FORMING COMPOUNDS EMPLOYING PLS

2006 ◽  
Vol 20 (14) ◽  
pp. 2019-2034 ◽  
Author(s):  
K. CHANDRAMANI SINGH ◽  
M. SHARMA ◽  
P. C. JAIN
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Liquid Crystalline ◽  
Positron Lifetime ◽  
Strong Temperature Dependence ◽  
Molecular Motions ◽  
Temperature Dependent ◽  
Slow Cooling ◽  
Positron Lifetime Spectroscopy ◽  
Motion Studies

Results of molecular motion studies carried out in two liquid crystal forming compounds n-p-cyano-p-hexyloxybiphenyl (M18) and n-p-ethoxybenzylidene-p-butylaniline (EBBA) using positron lifetime spectroscopy (PLS) are presented. Temperature dependent positron lifetime measurements have been performed in each compound during the heating cycle of samples prepared by either quenching or slow cooling from the respective liquid crystalline phase of the compounds. In both the compounds, behaviors of the quenched and slow cooled samples are found to be different. The material in the quenched sample, unlike the slow-cooled sample, exhibits strong temperature dependence before it undergoes a glass transition. In each case, the temperature dependence of o-Ps pick-off lifetime in the quenched sample shows broad peaks at various characteristic temperatures. These peaks have been attributed to various intra- and inter-molecular motions associated with these compounds. The characteristic frequencies of some of the modes observed in the present work agree well with the literature reported values obtained from FIR and Raman studies. The present study demonstrates the usefulness of PLS in the study of molecular motions.

Semirigid Homo- and Copoly(Imide-Carbonate)s Based on 3,4,3″,4″ -p-Terphenyltetracarboxdiimide

1998 ◽  
Vol 10 (1) ◽  
pp. 155-162 ◽  
Author(s):  
Moriyuki Sato ◽  
Seiji Ujiie ◽  
Yuji Tada ◽  
Takashi Kato
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Molar Ratio ◽  
Temperature Dependent ◽  
X Ray ◽  
Melt Polycondensation ◽  
Elemental Analyses ◽  
Temperature Ranges ◽  
Ft Ir ◽  
C Nmr

Novel thermotropic liquid crystalline (LC) semirigid homo- and copoly(imidecarbonate)s composed of a 3, 4, 3″, 4″- p-terphenyltetracarboxdiimide ring and aliphatic chains were prepared by melt polycondensation of a dihexanol derivative of 3, 4, 3″, 4″- p-terphenyltetracarboxdiimide and/or a dioxydihexanol of biphenyl taken in a definite molar ratio with hexamethylene diphenyl dicarbonate in the presence of zinc acetate, and their thermal and mesogenic properties were evaluated. The assigned structures of polymers were characterized by FT-IR and 13C NMR spectroscopy, and elemental analyses. DSC and TG-DTA measurements, polarizing microscope observations of textures and temperature-dependent x-ray analyses demonstrated that the polymers have wider LC temperature ranges (nematic phase) than analogous semirigid poly(ester-imide)s and are thermally stable up to 300 °C in air.

scholarly journals The Origin of the Helical Twist Inversion in Single Component Cholesteric Liquid Crystals

1994 ◽  
Vol 49 (11) ◽  
pp. 1081-1086 ◽  
Author(s):  
I. Dierking ◽  
F. Gießelmann ◽  
P. Zugenmaier ◽  
K. Mohr ◽  
H. Zaschke ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Single Component ◽  
Power Model ◽  
Temperature Dependent ◽  
First Approximation ◽  
Helical Twist ◽  
Chiral Centers ◽  
Crystalline System ◽  
The Individual ◽  
Liquid Crystalline System

Abstract The cholesteric twist inversion by temperature variation o f a single component thermotropic liquid crystalline system was experimentally investigated and is explained by the partial twisting power model, evaluating the temperature dependent pitch o f five different configurations of a benzoic acid biphenyl ester with two chiral centers. The temperature dependence o f the twisting power and the cholesteric pitch for several stereoisomeric compounds can in first approximation be predicted by the partial twisting powers of the individual chiral centers determined from the partially racemic configurations.

scholarly journals Polymorphism in N,N′-dialkyl-naphthalene diimides

2020 ◽  
Vol 8 (9) ◽  
pp. 3097-3112 ◽  
Author(s):  
Silvia Milita ◽  
Fabiola Liscio ◽  
Lewis Cowen ◽  
Massimiliano Cavallini ◽  
Ben A. Drain ◽  
...  
Keyword(s):  
Thin Films ◽  
Liquid Crystalline ◽  
Imaging Techniques ◽  
Polymorphic Behavior ◽  
Thermally Induced ◽  
Naphthalene Diimides

N-Alkyl naphthalene diimides show a highly versatile thermally-induced polymorphic behavior, including liquid crystalline mesophases, fully characterized in powders and thin films by combining thermal, diffraction and imaging techniques.

Temperature-Dependent Infrared Spectroscopy Studies of a Novel Antiferroelectric Liquid-Crystalline Thiobenzoate

2012 ◽  
Vol 116 (36) ◽  
pp. 11332-11343 ◽  
Author(s):  
Kacper Drużbicki ◽  
Antoni Kocot ◽  
Edward Mikuli ◽  
Mirosława Danuta Ossowska-Chruściel ◽  
Janusz Chruściel
Keyword(s):  
Infrared Spectroscopy ◽  
Liquid Crystalline ◽  
Temperature Dependent ◽  
Spectroscopy Studies
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