Dual-purpose liquid crystal intelligent paper for assisting braille teaching and preparation method of dual-purpose liquid crystal intelligent paper

Abstract

The invention relates to dual-purpose liquid crystal intelligent paper for assisting Braille teaching and a preparation method thereof, and provides a preparation scheme of the dual-purpose liquid crystal intelligent paper for Braille teaching, wherein the dual-purpose liquid crystal intelligent paper is used for Braille teaching, and the dual-purpose liquid crystal intelligent paper absorbs water and expands excessively after a cholesteric liquid crystal polymer network is subjected to alkali treatment. According to the scheme, the property that a hydrogen bond of a carboxylic acid functional group can be broken into carboxylate by alkali is utilized, so that a cholesteric liquid crystal polymer network obtains the characteristics that the cholesteric liquid crystal polymer network can be expanded in an ultra-large manner after absorbing water and the volume of a dried liquid crystal film is restored to the original shape, and thus fixed braille teaching paper and reusable braille writing paper are prepared. Processing the film by using alkali according to a certain braille point position, so that the braille appears when absorbing water and disappears when being dried, and preparing the fixed braille teaching paper; after the whole thin film is soaked in an alkaline solution, braille writing is carried out on the thin film with water as ink, after drying, braille disappears, writing can be continued, and the reusable braille teaching paper is prepared. The invention has the advantages of simple preparation, convenient carrying, obvious touch feeling, low cost and the like.

Description

(I) Technical Field

[0001] This invention belongs to the field of liquid crystal materials and displays. Specifically, it proposes a method for preparing liquid crystal smart paper that utilizes the property of cholesteric liquid crystal polymer film to expand greatly when exposed to water after alkali treatment, thereby achieving excellent tactile feedback, reusability, environmental friendliness, and low loss. (II) Background Technology

[0002] Braille reading is a fundamental skill that visually impaired individuals need to master in their daily lives. Most Braille instruction is conducted through printed books. During the learning process, teachers at schools for the blind explain the meaning of the tactile stimuli of Braille dots as students touch the materials, providing verbal guidance to help them establish a mapping between the tactile information of Braille dots and the written characters. However, printed Braille textbooks suffer from drawbacks such as long preparation cycles, complex processing techniques, high costs, fixed content that hinders flexible teaching, inconvenience in portability, and low efficiency in use and learning. Therefore, there is a need for a simple, reusable, and portable Braille learning tool to improve learning efficiency and enrich learning content.

[0003] Based on the above reasons, this patent proposes a cholesteric liquid crystal polymer network (CLCPN) film with the property of super-large expansion after water absorption, and provides preparation methods for two teaching aids: fixed Braille paper and erasable Braille paper. This liquid crystal material is created by connecting liquid crystal branches containing carboxylic acid functional groups to the main chain of the cholesteric liquid crystal within the film, and then using NaOH solution to break the hydrogen bonds of the carboxylic acid functional groups to form carboxylate salts, thereby giving the liquid crystal film the property of water absorption and expansion.

[0004] The liquid crystal molecules 1,4-bis-(4-(6-acryloyloxyhexyloxy)benzoyloxy)-2-methylbenzene (RM82) and 4-((6-((1-oxo-2-propenyl)oxy)hexyl)oxy)benzoic acid 4-methoxyphenyl ester (RM105) were thoroughly mixed with a chiral agent (LC756) to form a cholesteric phase liquid crystal. Then, water-sensitive molecules 4-(6-(acryloyloxy)hexyl)benzoic acid (6OBA) and 4-(4-(acryloyloxy)butoxy)benzoic acid (4OBA) were added to combine with the liquid crystal molecule RM82 to form the branched system in CLCPN. The crosslinking agents 2,2'-(ethylenedioxy)diethylphenol (EDDET) and pentaerythritol tetra-3-mercaptopropionate (PETMP) were added to give CLCPN a loose network structure, and the system was further permeable by removing unreacted organic matter with acetone. Because the porous structure facilitates the entry of water molecules, the loose network structure allows for extensive expansion, enabling CLCPN to swell dramatically after absorbing water. A cholesteric liquid crystal polymer network film is then obtained by uniformly orienting the film using the organic solvent polyvinyl alcohol (PVA). Immersing the prepared film in NaOH solution allows the entire film to absorb water and swell, thus enabling the preparation of erasable Braille teaching paper; while applying the alkaline solution to specific Braille dots produces fixed Braille teaching paper.

[0005] This patent is designed based on the optical properties of cholesteric liquid crystals. It solves the problems of long preparation cycle and complex processing technology of previous teaching paper, which leads to high cost, fixed text which is not conducive to flexible teaching and content updates, easy to be damaged, inconvenient to carry, and low efficiency of use and learning. It proposes a cholesteric liquid crystal smart paper with the characteristics of simple production, easy to carry, clear tactile sensation, green environmental protection and low loss, which can meet the requirements of more convenient and environmentally friendly Braille teaching. (III) Summary of the Invention

[0006] This invention aims to provide a dual-purpose liquid crystal smart paper for Braille teaching. It proposes a feasible solution to prepare fixed Braille paper and erasable Braille paper by utilizing the super absorbent properties of cholesteric liquid crystal polymer networks obtained after alkali treatment. It has the characteristics of convenient manufacturing, obvious tactile sensation, easy portability, and low loss.

[0007] The objective of this invention is achieved as follows:

[0008] CLCPN (Cholesteric Liquid Crystal Polymer) incorporates liquid crystal branches containing carboxylic acid functional groups in its main chain. Alkali treatment breaks the hydrogen bonds of these carboxylic acid functional groups, transforming them into carboxylates. This results in a porous and loose network structure, enabling CLCPN to absorb water and expand significantly. Specifically, PVA is used to uniformly orient CLCPN, followed by the addition of water-sensitive molecules 6OBA and 4OBA, which combine with liquid crystal molecules RM82 to form the branched system within CLCPN. Alkali treatment breaks the hydrogen bonds, forming carboxylates, thus creating the polymer network. With the aid of crosslinking agents EDDET, PETMP, and acetone, CLCPN develops a loose network structure, resulting in its ability to expand dramatically after absorbing water. The volume of the CLCPN film in the water-absorbing portion significantly expands compared to the non-water-absorbing portion, while the film returns to its original shape after drying. This allows for reusable Braille writing and can be used to prepare reusable Braille smart paper. When a fixed Braille teaching paper needs to be prepared, the Braille dot is written using an alkaline solution. When water is added to the film, there is only a large expansion at the Braille dot. After drying, it returns to its original shape, thus completing the preparation of the fixed Braille paper.

[0009] The fixed and erasable Braille paper for Braille teaching, based on the super-large water absorption and expansion properties of the cholesteric liquid crystal polymer network, are prepared by the following method:

[0010] 1. Mix liquid crystal monomers, chiral agents, water-sensitive materials, and plasticizers in a certain proportion and stir to form a homogeneous solution;

[0011] 2. Cool the mixed solution to room temperature, add crosslinking agent, photoinitiator and UV inhibitor and stir evenly. Then cast it onto the PVA-treated substrate and spread it flat to form a chiral solid film.

[0012] 3. Place the substrate in a fume hood until the organic solvent is completely evaporated, then use ultraviolet light to polymerize, and then use acetone to remove excess plasticizer monomers to finally produce a cholesteric liquid crystal polymer film.

[0013] Fourth, the prepared film is treated with an alkaline solution according to a certain Braille dot, so that the specific position of the film has water absorption and swelling properties, thus preparing fixed Braille teaching paper.

[0014] Fifth, the prepared film is treated with an alkaline solution to make the entire film have the property of absorbing water and swelling, thus producing reusable Braille writing paper.

[0015] The features and effects of this invention, including fixed Braille teaching paper and reusable Braille writing paper that expand dramatically after alkali treatment:

[0016] The main difference between this invention, a dual-purpose liquid crystal smart paper for Braille teaching, and existing ordinary Braille teaching paper lies in its approach: This invention leverages the significant volume change caused by the water absorption of carboxylate salts in a cholesteric liquid crystal polymer network. Alkali treatment breaks the hydrogen bonds of the carboxylate functional groups, transforming them into carboxylate salts. This allows the polymer network to achieve significant expansion after water absorption and return to its original shape after drying, thus enabling Braille writing. Fixed Braille teaching paper and reusable Braille teaching paper are prepared by treating the film separately at individual Braille dots and by treating the entire film with an alkaline solution. This invention offers advantages such as simple manufacturing, clear tactile feedback, portability, and low cost. (iv) Description of the attached drawings

[0017] Figure 1 This is a flowchart of the preparation process of cholesteric liquid crystal polymer networks.

[0018] The reference numerals in the figure are: (a) solution after uniform mixing of materials, (b) mixed solution spread on substrate, (c) UV irradiation, (d) acetone solution treatment, and (e) cholesteric phase liquid crystal polymer network film.

[0019] Figure 2 Flowcharts for the preparation of two types of Braille teaching paper

[0020] The figure shows (a) a film treated with NaOH solution according to a Braille dot, and (b) a film completely immersed in NaOH solution. (V) Detailed Implementation

[0021] 1. After rinsing thoroughly with acetone, rinse thoroughly with deionized water and cut the glass slides to a fixed size, then dry with nitrogen gas. Subsequently, spin-coat a 5 wt% PVA solution evenly onto the surface of the glass slide and place it in a drying oven at 60°C for 1 hour to completely dry to form a thin film. Then, rub it 10 times in the same direction with a velvet cloth.

[0022] 2. Add 115 mg of diacrylate liquid crystal molecule RM82, 25 mg of monoacrylate liquid crystal molecule RM105, 11 mg of chiral dopant LC756, 30 mg each of water-sensitive molecules 6OBA and 4OBA, and 30 mg of plasticizer 5CB to 190 mg of toluene. Stir the mixture at 1500 rpm for 10 minutes at 80°C to obtain a homogeneous solution.

[0023] 3. Cool the mixed solution to room temperature, then add 30 mg of crosslinking agent EDDET, 8 mg of PETMP, 2 mg of photoinitiator Irg8192 mg, and 2 mg of UV inhibitor in sequence. Stir the mixture at 1500 rpm for 3 minutes on a magnetic stirrer at 80°C, then pour it onto the treated substrate and spread it out. Allow it to evaporate freely in a dark environment at 45°C for 5 hours to form a chiral solid film.

[0024] 4. Place the mixture in a fume hood overnight to allow the organic solvent to evaporate completely. Maintain the temperature at 45°C and use 365nm and 20mw / cm. 2 Cholesteric liquid crystal network was prepared by UV polymerization for 2 hours. Then, unreacted 5CB was extracted with acetone to finally obtain a cholesteric liquid crystal polymer film.

[0025] 5. The prepared film is treated with NaOH solution at pH=10 according to a certain Braille dot to make fixed Braille teaching paper. When the teaching paper is soaked in water, the Braille appears and disappears after drying.

[0026] 6. The prepared cholesteric phase liquid crystal polymer network film is immersed in a NaOH solution with pH=10 to prepare reusable Braille teaching paper. This smart paper uses water as ink. Water is dripped on it to complete Braille writing. After drying, the Braille disappears and can be used for the next writing.

Claims

1. A dual-purpose liquid crystal smart paper for assisting Braille teaching and its preparation method, comprising steps including the preparation of a cholesteric phase liquid crystal polymer network film, the preparation of fixed Braille teaching paper, and the preparation of reusable Braille teaching paper. Its characteristic is... CLCPN treated with alkali will expand dramatically when it absorbs water, significantly increasing the volume of the water-absorbing area, making the tactile sensation more pronounced, and it is easy to operate using water as ink.

2. The dual-purpose liquid crystal smart paper for assisting Braille teaching and its manufacturing method according to claim 1, wherein the cholesteric phase liquid crystal polymer network film is prepared, characterized in that: Liquid crystal monomers RM82 and RM105, chiral agent LC756, water-sensitive molecules 6OBA and 4OBA, and plasticizer 5CB are dissolved in an organic solvent in a certain proportion. Then, crosslinking agents EDDET and PETMP, photoinitiator Irg819, and UV inhibitors are added to the homogeneous solution in a certain proportion. After thorough mixing, the mixture is spread evenly on a glass slide uniformly coated with PVA to form a uniformly oriented cholesteric liquid crystal film. After allowing the organic solvent to completely evaporate for a period of time, polymerization is performed using 365nm UV light to finally form a cholesteric liquid crystal polymer film containing hydrogen bonds.

3. The dual-purpose liquid crystal smart paper for assisting Braille teaching and its manufacturing method according to claim 1, wherein the preparation of the fixed Braille teaching paper is characterized in that: The film is treated with a NaOH solution of pH=10 according to a specific location of Braille. The treated area will absorb water and expand greatly, thus revealing the Braille. The Braille will disappear after drying.

4. The dual-purpose liquid crystal smart paper for assisting Braille teaching and its manufacturing method according to claim 1, and the reusable Braille teaching paper, characterized in that: The liquid crystal film is immersed in a NaOH solution with pH=10, and water is used as ink for Braille writing. After drying, the Braille is erased, and the writing can continue for the next time.

5. A dual-purpose liquid crystal smart paper for assisting Braille teaching and its manufacturing method, characterized in that: The hydrogen bonds of the carboxylic acid functional groups in the film treated with alkali are broken, transforming them into carboxylate salts, resulting in a super-large expansion property after water absorption. A fixed Braille teaching paper is prepared by treating the film according to specific Braille dots. A reusable Braille teaching paper is prepared by completely immersing a cholesteric liquid crystal polymer network film in an alkali solution. These methods are characterized by simple manufacturing, clear tactile feedback, portability, and low cost.

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