CN-122011446-A - Method for preparing large-area side chain type cholesteric liquid crystal elastomer film based on knife coating method and application

Abstract

The invention provides a method for preparing a large-area side chain type cholesteric liquid crystal elastomer film based on a knife coating method and application thereof. The invention realizes the simple and controllable preparation of a one-pot method by controlling the content of mercapto functional groups in a system and precisely controlling key process parameters such as the doctor-blade speed, the doctor-blade temperature and the like in the doctor-blade process, and the prepared large-area side chain type cholesteric liquid crystal elastomer film has the dual response characteristics of both mechanochromism and thermochromism, has wide application prospect in the fields of color change materials, strain sensing, intelligent anti-counterfeiting, soft robots and the like, provides a new thought for controllable preparation of high-performance intelligent response materials, and opens up a new technical route for manufacturing large-area customizable functional films.

Inventors

• LI JING
• Lao Fengxian
• CHEN XUDONG
• YANG YUZHAO
• ZHONG SHILONG
• LI XUEQI
• WU ZIYANG
• HUANG JIAQI

Assignees

• 广东工业大学

Dates

Publication Date

20260512

Application Date

20260106

Claims (10)

1. 1. The method for preparing the large-area side chain type cholesteric liquid crystal elastomer film based on the knife coating method is characterized by comprising the following steps of: carrying out hot mixing treatment on a raw material system comprising double-end acrylate group liquid crystal molecules, single-end acrylate group nematic liquid crystal molecules, chiral dopants, photoinitiators, mercapto molecules and solvents to obtain a mixed solution; Heating the mixed solution to volatilize the solvent to obtain a cholesteric liquid crystal elastomer oligomer precursor; The cholesteric liquid crystal elastomer precursor is directly scraped on the surface of a substrate by a scraping method, so that a cholesteric liquid crystal elastomer oligomer film with an orientation structure is obtained; and (3) crosslinking and curing the cholesteric liquid crystal elastomer oligomer film under the irradiation of light to obtain the large-area side chain type cholesteric liquid crystal elastomer film.
2. 2. The method for preparing a large-area side-chain cholesteric liquid crystal elastomer film based on a knife coating method according to claim 1, wherein the double-end acrylate group liquid crystal molecules are a liquid crystal monomer RM82, the single-end acrylate group nematic liquid crystal molecules are a liquid crystal monomer RM105, the chiral dopant is LC756, the photoinitiator is IRG651, and the mercapto molecule is 1, 6-hexanedithiol.
3. 3. The method for preparing a large-area side-chain cholesteric liquid crystal elastomer film based on a knife coating method according to claim 2, wherein the mass ratio of the double-end acrylate group liquid crystal molecules, the single-end acrylate group nematic liquid crystal molecules, the chiral dopant, the photoinitiator and the mercapto molecule is 0.36:5.34 (0.21-0.4): 0.1:1.
4. 4. The method for preparing a large-area side-chain type cholesteric liquid crystal elastomer film based on a knife coating method according to claim 1, wherein the heating treatment is carried out at a temperature of 90-110 ℃ for 2-4 hours.
5. 5. The method for preparing a large-area side-chain type cholesteric liquid crystal elastomer film based on a knife coating method according to claim 1, wherein the technological parameters of the knife coating method comprise: The doctor blade speed is 1-10mm/s, the doctor blade temperature is 30-60 ℃, and the doctor blade thickness is 100-250 mu m.
6. 6. The method for preparing a large-area side-chain type cholesteric liquid crystal elastomer film based on a knife coating method according to claim 1, wherein the cross-linking and curing temperature is 30-60 ℃ and the time is 5-10min.
7. 7. The method for preparing a large-area side-chain type cholesteric liquid crystal elastomer film based on a knife coating method as claimed in claim 1, wherein the illumination condition is ultraviolet light with the wavelength of 365nm and the power of 6-10mW/cm 2 .
8. 8. A large area side chain type cholesteric liquid crystal elastomer film, characterized in that it is produced by the production method according to any one of claims 1 to 7.
9. 9. Use of a large area side chain type cholesteric liquid crystal elastomer film according to claim 8 as a security tag.
10. 10. Use of a large area side chain type cholesteric liquid crystal elastomer film according to claim 8 for the preparation of thermochromic and/or mechanochromatic materials.

Description

Method for preparing large-area side chain type cholesteric liquid crystal elastomer film based on knife coating method and application Technical Field The invention relates to the technical field of liquid crystal material preparation, in particular to a method for preparing a large-area side chain type cholesteric liquid crystal elastomer film based on a knife coating method and application thereof. Background Liquid Crystal Elastomers (LCEs) are of interest in the field of smart response because of their combination of liquid crystal anisotropy and polymer network elasticity. The Cholesteric Liquid Crystal Elastomer (CLCE) has a self-organized spiral structure, can realize Bragg reflection of circularly polarized light with specific wavelength, has reflection wavelength lambda=n.P (n is average refractive index and P is spiral pitch), and can be colored without dye in the visible light range. In various CLCE, compared with the main chain type CLCE, the side chain type CLCE has higher molecular motion freedom degree, has obvious advantages in the aspects of response sensitivity to external stimuli (such as force and heat), speed and optical variation amplitude, and has important application value in the fields of strain sensing, self-adaptive optical systems, intelligent anti-counterfeiting, soft robots and the like. Currently, conventional methods for preparing Cholesteric Liquid Crystal Elastomer (CLCE) films mainly include a solvent evaporation method and a liquid crystal cell-based alignment technology. The alignment technology based on the liquid crystal box can control the arrangement, but the precursor is required to be volatilized and concentrated before being poured into the box, the preparation area is limited by the size of the box body, the process steps are complicated, large-area continuous production cannot be realized, and the industrial conversion potential is severely restricted. Therefore, developing a novel process capable of realizing rapid orientation and large-area preparation of side chain type cholesteric liquid crystal elastomer films is a problem to be solved in the art. Disclosure of Invention The invention provides a method for preparing a large-area side-chain cholesteric liquid crystal elastomer film based on a knife coating method. The preparation method is simple and can be widely popularized and applied. The invention also provides a large-area side-chain cholesteric liquid crystal elastomer film prepared by the preparation method, and the large-area side-chain cholesteric liquid crystal elastomer film has the dual response characteristics of mechanochromism and thermochromism. The invention also provides an application of the large-area side-chain cholesteric liquid crystal elastomer film prepared by the preparation method as an anti-counterfeit label. The invention also provides an application of the large-area side chain type cholesteric liquid crystal elastomer film prepared by the preparation method in the preparation of thermochromic materials and/or mechanochromatic materials. The first aspect of the invention provides a method for preparing a large-area side-chain cholesteric liquid crystal elastomer film based on a knife coating method, which comprises the following steps: carrying out hot mixing treatment on a raw material system comprising double-end acrylate group liquid crystal molecules, single-end acrylate group nematic liquid crystal molecules, chiral dopants, photoinitiators, mercapto molecules and solvents to obtain a mixed solution; Heating the mixed solution to volatilize the solvent to obtain a cholesteric liquid crystal elastomer oligomer precursor; The cholesteric liquid crystal elastomer precursor is directly scraped on the surface of a substrate by a scraping method, so that a cholesteric liquid crystal elastomer oligomer film with an orientation structure is obtained; and (3) crosslinking and curing the cholesteric liquid crystal elastomer oligomer film under the irradiation of light to obtain the large-area side chain type cholesteric liquid crystal elastomer film. According to the method for preparing the large-area side chain type cholesteric liquid crystal elastomer film based on the knife coating method, the double-end acrylate group liquid crystal molecules are the liquid crystal monomer RM82, the single-end acrylate group nematic liquid crystal molecules are the liquid crystal monomer RM105, the chiral dopant is LC756, the photoinitiator is IRG651, and the mercapto molecule is 1, 6-hexanedithiol. The method for preparing the large-area side chain type cholesteric liquid crystal elastomer film based on the knife coating method comprises the steps of enabling the mass ratio of the double-end acrylate group liquid crystal molecules to the single-end acrylate group nematic liquid crystal molecules to the chiral dopant to the photoinitiator to the mercapto molecule to be 0.36:5.34 (0.21-0.4): 0.1:1. The method for preparing the large-area side-