研究目的
To contribute to better understanding of the effect of the absolute configuration and phase sequences of dopants on the self-assembling and physicochemical properties as well as on the electro-optical parameters of a specific liquid crystalline mixture with a broad temperature range of the antiferroelectric phase.
研究成果
The formulation of mixtures using enantiomers with the different absolute configuration enables to tune effectively the physicochemical properties of the targeted antiferroelectric liquid crystalline mixtures. The novel findings presented in the work opens new routes for design of new orthoconic antiferroelectric self-assembling materials with long helical pitch and electro-optical properties responding demands of various practical applications.
研究不足
The study is limited to the specific enantiomers and the W-432 base mixture used. The effects of other types of dopants or base mixtures are not explored. The electro-optical measurements were done at a specific temperature (30oC), which may not represent the behavior at other temperatures.
1：Experimental Design and Method Selection:
The study involved the formulation of multicomponent antiferroelectric liquid crystalline mixtures doped with (S) and (R) enantiomers. The mesomorphic behaviour, helical pitch length, spontaneous polarization, tilt angle, and electro-optical performance were determined.
2：Sample Selection and Data Sources:
Several (S) and (R) enantiomers, containing three phenyl rings in the molecular core, were used as dopants for the formulation of multicomponent mixtures. The W-432 base mixture was selected and used for the formulation of target mixtures.
3：List of Experimental Equipment and Materials:
Polarising optical microscope (POM) (OLYMPUS BX51, Japan), heating stage (Linkam THMS-600), temperature controller (Linkam TMS-93), Differential Scanning Calorimetry (DSC) (DSC 204 F1 Phoenix (Netzsch)), Shimadzu UV–Vis–NIR spectrometer, AMLWU7 temperature controller, homeotropically aligned samples, planar cells with transparent electrodes of indium-tin-oxide (ITO), SE-130 Nissan Chem. poliimide, Mylar? sheets, R&S HMF 2550 function generator, amplifier F20AD, digital storage oscilloscope (R&S HM0724), photodetector PDA100A by Thorlabs.
4：Experimental Procedures and Operational Workflow:
The sequence of phases and phase transitions temperatures were observed using POM and DSC. Helical pitch measurements were done based on selective light reflection phenomenon. The spontaneous polarization and tilt angle were measured on the planar cells in bookshelf geometry. The electro-optical response was studied under applying a square wave pulse.
5：Data Analysis Methods:
The helical pitch was calculated using equations based on selective light reflection. Spontaneous polarization was determined using the reversal current method. Tilt angle was measured from the electro-optic response. Rotational viscosity was calculated from the measurements of the switching on time.
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Polarising optical microscope
BX51
OLYMPUS
Observation of sequence of phase and phase transitions temperatures
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Function generator
HMF 2550
R&S
Generation of triangular wave for spontaneous polarization measurement
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Digital storage oscilloscope
HM0724
R&S
Recording of the electrical current from the voltage drop across the resistor
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Photodetector
PDA100A
Thorlabs
Detection of extinction positions for tilt angle measurement
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Heating stage
THMS-600
Linkam
Temperature control during observations
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Temperature controller
TMS-93
Linkam
Temperature stabilization within ±0.1°C
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Differential Scanning Calorimetry
DSC 204 F1 Phoenix
Netzsch
Measurement of phase transitions temperatures and enthalpies
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UV–Vis–NIR spectrometer
Shimadzu
Measurement of light transmission
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Temperature controller
AMLWU7
Temperature control within the range 2-110°C
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Amplifier
F20AD
Amplification of the signal from function generator
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