CN-119529340-B - Self-positioning flexible circularly polarized light conversion film and preparation method thereof

Abstract

The invention relates to the field of luminescent materials, in particular to a self-positioning flexible circularly polarized light conversion film and a preparation method thereof. According to the preparation method provided by the invention, a high-quality photopolymerization material represented by polyacrylamide prepolymer is synthesized by a solvothermal method, a proper molecule with macroscopic assembly capability, a chiral dopant and an oil-water amphiphilic substance are selected, the four substances are mixed according to a certain proportion, are mixed at a certain rotating speed under the action of a homogenizer, and then are self-assembled under the irradiation of ultraviolet light at a certain temperature, so that the flexible film with a circularly polarized light conversion effect is finally obtained. The self-positioning flexible circularly polarized light conversion film prepared by the invention can simultaneously improve the asymmetry factor and the processing capacity of circularly polarized light of the material.

Inventors

• Zhuang Taotao
• GUO QI

Assignees

• 中国科学技术大学

Dates

Publication Date

20260512

Application Date

20241120

Claims (6)

1. 1. The preparation method of the self-positioning flexible circularly polarized light conversion film is characterized by comprising the following steps of: s1, mixing acrylamide, polyacrylamide, a photoinduction agent, a crosslinking agent and a solvent, and heating for reaction to obtain a photopolymerization material; s2, mixing a material with macroscopic co-assembly capability, an organic chiral dopant and a solvent, and then removing the solvent to obtain a chiral liquid crystal material; s3, mixing the photopolymerized material obtained in the step S1, the chiral liquid crystal material obtained in the step S2 and the oil-water amphiphilic substance solution, and irradiating the mixture with ultraviolet light to obtain a self-positioning flexible circularly polarized light conversion film; Wherein, step S1 and step S2 are not limited in sequence; In the step S2, the material with macroscopic co-assembly capability is at least one of 4' -n-amyl-4-cyanobiphenyl, 4' -n-pentyloxy-4-cyanobiphenyl, 4' -n-heptyl-4-cyanobiphenyl, 4' -n-octyloxy-4-cyanobiphenyl, 4' -n-amyl-4-cyanobiphenyl and liquid crystal E7; In step S2, the organic chiral dopant is a compound represented by formula (I) and/or a compound represented by formula (II): Formula (I); Formula (II); in the step S3, the oil-water amphiphilic substance in the oil-water amphiphilic substance solution is PVA, and the mass percentage concentration of the oil-water amphiphilic substance solution is 8% -12%; The mass percentages of the materials are as follows: 75.00% -85.00% of the photopolymerized material obtained in the step S1; 0.20% -0.60% of organic chiral dopants used in the step S2; 10.00% -20.00% of a material with macroscopic co-assembly capability used in the step S2; 2.00% -6.00% of oil-water amphiphilic substance; The total amount of the four substances is 100%.
2. 2. The preparation method according to claim 1, wherein in the step S1, the weight average molecular weight of the polyacrylamide is 200 to 2000 tens of thousands; the mass ratio of the polyacrylamide to the acrylamide is 1 (6-7).
3. 3. The method according to claim 1, wherein in step S1, the photoinduction agent is N, N' -methylenebisacrylamide; the dosage of the photoinduction agent is 1.2-1.8% of the mass of the acrylamide.
4. 4. The method according to claim 1, wherein in step S1, the crosslinking agent is 2-hydroxy-2-methyl propenone; the dosage of the cross-linking agent is 1.2% -1.8% of the mass of the acrylamide.
5. 5. The preparation method according to claim 1, wherein in the step S3, the ultraviolet light is irradiated at 365nm wavelength for 5-20 min at 25-40 ℃.
6. 6. A self-aligned flexible circularly polarized light conversion film produced by the production method of any one of claims 1 to 5.

Description

Self-positioning flexible circularly polarized light conversion film and preparation method thereof Technical Field The invention relates to the technical field of luminescent materials, in particular to a self-positioning flexible circularly polarized light conversion film and a preparation method thereof. Background Chiral is an important phenomenon in nature and has important influence on a plurality of fields such as chemistry, physics, biology and the like. The geometry of chiral molecules makes them optically exhibit unique properties, with chiral luminescence (CPL) receiving widespread attention as a special chiral phenomenon. The chiral luminescent system can generate left-handed and right-handed circularly polarized light with different characteristics after excitation. The characteristic has important value in the front application fields of asymmetric synthesis, chemical sensors, 3D display technology, quantum computation and the like. By studying these materials, the structural information of chiral molecules in the excited state can be more deeply understood, thereby revealing chiral generation, transmission and amplification mechanisms. At the same time, as understanding of chiral luminescence is enhanced, the design and synthesis of higher performance chiral materials are facilitated, and the new materials are expected to exert unique advantages in wider applications. For example, chiral luminescent materials exhibit great potential for application in the fields of optoelectronic devices, biological detectors, and the like. Therefore, the continuous research of chiral luminescent materials not only helps to expand basic scientific knowledge, but also opens up new possibilities for the development of related technologies. As an important parameter of circularly polarized light, the asymmetry factor of circularly polarized light-g lum, which is defined as: Wherein I L and I R are respectively the luminous intensities of left-handed circularly polarized light and right-handed circularly polarized light in the total luminous intensity of the luminous system, and the value range of g lum is between-2 and +2 according to the expression. The magnitude of g lum value basically determines the possibility of putting the circular polarization luminescent material into practical application, so how to increase the luminescent asymmetry factor as much as possible is one of the key problems in the current circular polarization luminescent material field. The liquid crystal material is composed of rigid rod-shaped molecules, and forms a spiral stacking structure when receiving spiral torsion force, so that the luminous asymmetry factor is remarkably improved. A great deal of researches show that the chiral liquid crystal can effectively improve the luminous asymmetry factor value. The spiral structure of the chiral liquid crystal can convert microscopic chirality into a macroscopic structure, thereby realizing chiral amplification. In addition, the pitch of the chiral liquid crystal can be adjusted to change the photon forbidden band position of the chiral liquid crystal, so that the chiral liquid crystal has strong selective reflection on light with specific wavelength. Two main types of chiral liquid crystal materials that have been reported to date are chiral dopant induced hybrid liquid crystal materials and chiral liquid crystal materials formed of chiral liquid crystal molecules. The chiral dopant induced mixed liquid crystal material is paid attention to because of the advantages of simple preparation, multiple liquid crystal types, simple performance adjustment of photon forbidden bands and the like. Chiral dopant-like chiral liquid crystal materials may be prepared by mixing a chiral agent with nematic liquid crystal, or by co-dissolving a chiral dopant with nematic liquid crystal in a solvent, followed by slow evaporation of the solvent. In 2019, researchers have prepared three-component doped circularly polarized luminescent liquid crystal materials by changing the types of chiral dopants, luminescent substances and liquid crystals, and have obtained higher asymmetry factors. In addition, researchers have obtained a multi-component co-assembled chiral light emitting system by mixing and assembling chiral dopants, mixed liquid crystals, up-conversion particles, and perovskite nanoparticles, and realized high levels of asymmetry factors by adjusting pitch and photon forbidden bands. The reported mixed chiral liquid crystal material has remarkable progress in the aspects of preparation method, performance regulation and the like. However, there are also some disadvantages, most of the reported systems are still in the photoluminescence phase, the displayed circularly polarized light is fixed, and most of the circularly polarized light is in a fluid state, and the display of the circularly polarized light property needs the assistance of special devices such as a liquid crystal box, and the general