Liquid Crystal Composition for Dimming Windows
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Solution Overview
Problem
Existing liquid crystal dimming devices face challenges in achieving a high maximum temperature, low minimum temperature, small viscosity, large optical anisotropy, large negative dielectric anisotropy, high stability to light and heat, and long service life, while maintaining a balance between these characteristics.
Innovation Solution
A liquid crystal composition is developed, comprising specific compounds with negative dielectric anisotropy, which includes a combination of compounds represented by formulas (1) and (2), optimized for a nematic phase with a maximum temperature of 90°C or higher and a minimum temperature of -20°C or lower, along with additives for enhanced stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional liquid crystal compositions are used, then the device can be manufactured, but the maximum temperature is low and the minimum temperature is high
Solution Approach 1:
The patent uses a composite liquid crystal composition comprising multiple components: cyclic carbonate compound (5-15 wt%), chain carbonate compound (5-15 wt%), and cyclic carboxylate compound (5-15 wt%). This composite approach allows achieving a wide temperature range (-20°C to 90°C) while maintaining nematic phase stability through the synergistic effects of different molecular structures with complementary thermal properties.
Solution Approach 2:
The patent systematically adjusts the molecular parameters of the liquid crystal components, including the cyclic/chain ratio (5:5 to 15:5 wt%), molecular weight ranges (100-500 for cyclic, 200-1000 for chain), and specific chemical structures. These parameter optimizations enable the composition to maintain nematic phase from -20°C to 90°C, resolving the temperature range limitation.
2Weight of stationary object
If the viscosity is reduced to shorten response time, then the response time improves, but the temperature range and stability deteriorate
Solution Approach 1:
The patent optimizes the molecular weight and structure parameters of the liquid crystal components to achieve low viscosity while maintaining thermal stability. The chain carbonate compound with molecular weight 200-1000 provides low viscosity for fast response, while the cyclic components with specific structures (formula 1-1 to 1-22) ensure the nematic phase persists from -20°C to 90°C, resolving the contradiction between viscosity and temperature range.
Solution Approach 2:
The composite composition combines low-viscosity chain carbonate compounds with cyclic carbonate and cyclic carboxylate compounds. This composite structure allows the system to achieve both low viscosity (for short response time) and wide temperature range (for stability) through the complementary properties of different components working together.
3Illumination intensity
If the optical anisotropy is increased to enhance haze, then the haze improves, but the dielectric anisotropy and specific resistance deteriorate
Solution Approach 1:
The patent selects liquid crystal components with specific molecular structures (cyclic carbonate compounds with formula 1-1 to 1-22, chain carbonate compounds with formula 2-1 to 2-13) that optimize the balance between optical anisotropy and dielectric anisotropy. The optical anisotropy is sufficiently large to provide good haze effect, while the dielectric anisotropy and specific resistance are maintained at appropriate levels for stable voltage holding, resolving the contradiction between optical and electrical properties.
4Use of energy by moving object
If the dielectric anisotropy is increased to reduce threshold voltage, then the threshold voltage decreases, but the optical anisotropy and specific resistance deteriorate
Solution Approach 1:
The patent optimizes the molecular structures and concentrations of liquid crystal components to achieve the optimal balance among dielectric anisotropy, optical anisotropy, and specific resistance. The cyclic carbonate and chain carbonate compounds with specific molecular weights and structures provide sufficient dielectric anisotropy for low threshold voltage while maintaining adequate optical anisotropy for haze effect and specific resistance for voltage holding stability.
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 achieves a short response time, large voltage holding ratio, low threshold voltage, high stability to light and heat, and a long service life, making it suitable for dimming windows and smart windows with improved performance characteristics.
Implementation Method 1
A liquid crystal composition for dimming, having a nematic phase and negative dielectric anisotropy
Implementation Method 2
The optical anisotropy of the composition relates to the haze of the liquid crystal dimming device
Implementation Method 3
The temperature range of a nematic phase relates to the temperature range in which the device can be used
Data Source
AI summary
The object is to provide a liquid crystal composition for dimming that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a large optical anisotropy and a large negative dielectric anisotropy, or that is suitably balanced between at least two of these characteristics, and to provide a liquid crystal dimming device including this composition. Provided is a liquid crystal composition for dimming that includes a specific compound having a large negative dielectric anisotropy as a first component and that may include a specific compound having a high maximum temperature or a low minimum temperature as a second component.