Nematic Liquid Crystal Composition for Low Viscosity and High Dielectric Anisotropy
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Solution Overview
Problem
Existing liquid crystal compositions with positive dielectric anisotropy do not achieve sufficiently low viscosity while maintaining a wide nematic phase temperature range and high nematic phase-isotropic liquid phase transition temperature.
Innovation Solution
A liquid crystal composition combining specific fluorobenzene derivatives represented by general formulas (LC0) to (LC5), incorporating compounds with a tetrahydropyran-2,5-diyl group, which adjusts refractive index anisotropy and dielectric anisotropy to achieve low viscosity and stable phase over a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If liquid crystal compositions use compounds with positive dielectric anisotropy (Δ∈) as disclosed in PTL 1 to PTL 4, then dielectric anisotropy is achieved, but viscosity is not sufficiently low
Solution Approach 1:
The patent employs a composite liquid crystal composition comprising multiple compounds including fluorobenzene derivatives with specific structural features (formulae LC1-LC5), cyclic carbonate compounds (formula LC6), and compounds of formula (I). This composite approach combines materials with complementary properties to achieve both sufficient dielectric anisotropy and reduced viscosity, resolving the contradiction between these two parameters.
Solution Approach 2:
The patent systematically varies molecular parameters such as substituent types (fluorine, cyano, alkoxy groups), molecular weight, and structural rigidity of the liquid crystal compounds. By adjusting these parameters within specific ranges, the composition achieves optimal balance between dielectric anisotropy and viscosity, enabling low-viscosity operation while maintaining positive Δ∈.
2Speed
If viscosity is reduced for high-speed response, then response speed improves, but nematic phase temperature range may narrow
Solution Approach 1:
The multi-component composite formulation allows each compound to contribute differently to the overall properties. The combination of fluorobenzene derivatives, cyclic carbonates, and formula (I) compounds creates synergistic effects that maintain wide nematic phase temperature ranges while achieving low viscosity for fast response, preventing the trade-off between these parameters.
Solution Approach 2:
Different compounds in the composition serve localized functional roles: some compounds primarily contribute to dielectric anisotropy, others to viscosity reduction, and others to temperature range stabilization. This functional differentiation within the composite allows simultaneous optimization of response speed and temperature stability without compromise.
3Force
If dielectric anisotropy (Δ∈) is increased for low-voltage driving, then drive voltage decreases, but viscosity may increase
Solution Approach 1:
The patent introduces fluorine substituents at specific positions on the benzene ring, which significantly enhance dielectric anisotropy through their electron-withdrawing effect and molecular polarizability. Simultaneously, the compact molecular structure and specific substituent patterns maintain low intermolecular friction, preventing viscosity increase despite the enhanced dielectric properties.
Solution Approach 2:
The patent replaces traditional mechanisms for achieving dielectric anisotropy (such as using high molecular weight or rigid structures) with a chemical substitution approach using fluorine atoms. This substitution provides enhanced dielectric response without the mechanical side effect of increased viscosity, as fluorine's small size and high electronegativity provide electronic polarization without mechanical friction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition exhibits a large positive dielectric anisotropy, low rotational viscosity, and chemical stability against heat, light, and water, enabling low-voltage operation with high reliability and excellent liquid crystal properties.
Implementation Method 1
a liquid crystal composition having positive dielectric anisotropy (Δ∈)
Implementation Method 2
an image is displayed by applying an IPS/FFS-mode electric field
Implementation Method 3
refractive index anisotropy (Δn)
Implementation Method 4
nematic phase-isotropic liquid phase transition temperature (Tni)
Data Source
AI summary
A liquid crystal composition exhibits a positive dielectric anisotropy and sufficiently low viscosity without decreasing or increasing refractive index anisotropy or nematic phase-isotropic liquid phase transition temperature, and does not cause display failures. The liquid crystal composition contains one or more compounds selected from compounds represented by general formula (LC0) and one or more compounds selected from a group of compounds represented by general formula (LC1) to general formula (LC5), in which the liquid crystal composition contains one or more compounds in which at least one of A01, A02, and A11 to A42 in general formulae (LC0) to (LC4) represents a tetrahydropyran-2,5-diyl group.