Method for controlling liquid crystal reflection color by using fluorine substituted azobenzene

A technology of azobenzene and liquid crystal, which is applied in the field of regulating the reflection color of liquid crystal, and can solve the problems that hinder the practical application of liquid crystal materials, such as red, green and blue primary colors, etc.

Active Publication Date: 2019-06-11
FUDAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, at present, the control of the reflection color of liquid crystals is limited to the transition state, and multiple factors such as the wavelength of the stimulating light, light intensity, and irradiation time must be considered at the same time. Practical applications in various fields

Method used

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  • Method for controlling liquid crystal reflection color by using fluorine substituted azobenzene
  • Method for controlling liquid crystal reflection color by using fluorine substituted azobenzene
  • Method for controlling liquid crystal reflection color by using fluorine substituted azobenzene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0069] Prepare a fluorine-substituted azobenzene molecule conforming to the general structure, as shown in the following formula:

[0070]

[0071] Add 4-methoxy-2,6-difluoroaniline (5.0 g), hydrochloric acid (15 ml) and aqueous solution (24 mL) into a 500 mL round bottom flask, and cool to 0°C. Under stirring, an aqueous solution (30 mL) of sodium nitrite (3 g) was slowly added dropwise to the system. Then 3,5-difluorophenol (6 g) and sodium hydroxide (5 g) in water (50 mL) were added dropwise. After the dropwise addition was complete, stirring was continued for 3 hours. After adjusting the pH to 4, the reaction solution was filtered, and the filter cake was washed with distilled water to obtain a crude product, which was subjected to column chromatography with dichloromethane as the eluent to obtain an orange solid. Immediately after the product was obtained as an orange solid, the next reaction was carried out. Add orange solid, 1-bromopentane (8g), potassium carbonat...

Embodiment 2

[0074] The fluorine-substituted azobenzene prepared in Example 1 was dissolved in a methylene chloride solution, and at room temperature, the ultraviolet-visible absorption spectrometer was used to detect ultraviolet light at 365 nanometers, green light at 530 nanometers, and blue light at 405 nanometers Changes under irradiation.

[0075] Test results such as image 3 As shown, under the irradiation of different wavelengths of light, the absorption spectrum curves are different. In the initial state, the fluorine-substituted azobenzenes in the system are all trans isomers; under the irradiation of 365 nm ultraviolet light, the absorption peak position at 350 nm is the lowest, and the fluorine-substituted azobenzene trans isomers and cis The ratio of isomers is 1 / 4; under the irradiation of green light at 530 nanometers, the absorption peak at 350 nanometers is in the middle position, and the ratio of fluorine-substituted azobenzene trans isomers and cis isomers in the system...

Embodiment 3

[0077] With the fluorine-substituted azobenzene prepared in embodiment 1, the chiral dopant binaphthyl derivative (structure such as figure 1 Shown) and mixed liquid crystal E7 (structure such as figure 2 Shown) according to the mass ratio of 12% / 7% / 81%, mix evenly and pour in the liquid crystal cell of parallel alignment, at room temperature, use 405 nanometer blue light, 530 nanometer green light, 365 nanometer ultraviolet light to liquid crystal cell Perform irradiation to reach a stable state, use a polarizing microscope to observe the reflection color of the liquid crystal, and use a reflectance spectrometer to measure the position of the reflection peak.

[0078] Test results such as Figure 4 and Figure 5 As shown, under the irradiation of light of different wavelengths, the reflection colors of liquid crystals are different. Under the irradiation of ultraviolet light of 365 nanometers, the reflection color of liquid crystal is red, and the reflection peak is locat...

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Abstract

The invention belongs to the technical field of liquid crystal materials, in particular to a method for controlling a liquid crystal reflection color by using fluorine substituted azobenzene. The fluorine substituted azobenzene used in the method has the characteristic of multi-wavelength light response, and the cis-trans isomerization reaction with different degrees of the fluorine substituted azobenzene can be carried out under the irradiation of different wavelength lights. According to the method, the fluorine substituted azobenzene, a chiral dopant and a liquid crystal matrix are evenly mixed in a certain proportion, and then the mixture is poured into a liquid crystal cell. By changing a wavelength of a stimulus light source, the precise regulation of the reflection color of the liquid crystal cell to be red, green and blue can be realized. The control method uses the light steady state to control the liquid crystal reflection color, and the limitation of a traditional method that the transition state is used to control the reflection color is broken through. The method can be applied to numerous fields, such as liquid crystal display, optical logic switch, optical storage, anti-counterfeiting, and the like.

Description

technical field [0001] The invention belongs to the technical field of liquid crystal materials, and in particular relates to a method for regulating and controlling the reflection color of liquid crystals. Background technique [0002] Chiral nematic liquid crystal is a kind of material with excellent performance and supramolecular helical structure, which can change its own molecular arrangement and various optical properties under the stimulation of external electric field, magnetic field, heat, chemical reaction or light. Among many stimulation methods, light stimulation has advantages because it can provide remote fixed-point regulation and is clean and pollution-free. Photoresponsive chiral nematic liquid crystals have broad application prospects in liquid crystal display, optical logic switch, optical storage, anti-counterfeiting and other fields. [0003] Azobenzene compounds can change from the rod-shaped trans isomer to the curved cis-isomer under the irradiation ...

Claims

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Application Information

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IPC IPC(8): C09K19/52
Inventor 俞燕蕾秦朗韦嘉
Owner FUDAN UNIV
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