Novel multimode display material and method of making same

Abstract

The application discloses a novel multi-mode display material and a preparation method thereof. The novel multi-mode display material comprises a multi-mode display layer, and the multi-mode display layer is formed by compounding a CLCE matrix and an up-conversion luminescent material. The CLCE matrix is a controllable cross-linking density elastic network with a spiral superstructure, and the spiral pitch of the CLCE matrix is regulated by a chiral agent concentration, a mechanical force or heat, so that a photonic band gap is regulated. Meanwhile, the chiral agent can also regulate a chiral selective reflection function through the chirality of the chiral agent. The up-conversion luminescent material comprises a functionalized luminescent component, the functionalized luminescent component is combined with the CLCE matrix through a covalent grafting or an adaptive dispersion mode, and the functionalized luminescent component can generate up-conversion luminescence under excitation of specific wavelength light. Through the synergistic effect of the CLCE matrix and the up-conversion luminescent material, the multi-mode display layer has four-dimensional orthogonal optical functions of mechanical response, thermal response, light response and chiral selective reflection.

Description

Technical Field

[0001] This invention relates to the field of stimulus-responsive photonic materials technology, and in particular to a novel multimode display material and its preparation method. Background Technology

[0002] Stimulus-responsive photonic materials can convert external stimuli such as mechanical force, temperature, and light into visible optical signals by controlling the absorption, reflection, and interference of photons. This is one of the core research directions in the fields of intelligent optical devices, information security, and dynamic displays. Cholesteric liquid crystal elastomers (CLCEs), as a novel type of stimulus-responsive photonic material combining the orderliness of liquid crystal phases with the flexibility of polymeric elastomer networks, have become a research hotspot in this field due to their unique helical superstructure and dynamically tunable photonic bandgap (PBG). CLCEs possess self-supporting properties, and their pitch can be reversibly controlled through mechanical stretching and temperature changes, thereby achieving dynamic switching of structural colors. They also exhibit chiral selective reflection properties, demonstrating significant application potential in scenarios such as optical encryption and dynamic information displays.

[0003] However, the research and application of CLCE in the current technology still have many inherent bottlenecks: First, pure CLCE can only achieve single-dimensional control of structural color by mechanical force or thermal action, without additional photoresponse luminescence function, and the response dimension is lacking. Optical encryption based on pure CLCE can only rely on structural color to realize information expression, which is easy to be forged in complex environments and has limited anti-cracking ability, making it difficult to meet the application requirements of advanced optical encryption. Second, the composite modification of ordinary luminescent materials to expand the function of CLCE in the current technology all have significant compatibility and stability defects. For example, the method of physically doping quantum dots, conventional fluorescent molecules and other luminescent materials is prone to problems such as phase separation and fluorescence quenching, which leads to rapid decay of the optical performance of the material. Although a few chemical doping modification methods can improve the binding stability of luminescent materials and CLCE matrix to a certain extent, they mostly rely on chemical stimulation to achieve luminescence control, which is cumbersome to use and the range of luminescent materials that can be adapted is limited, and it cannot meet the diversified functional expansion needs.

[0004] Triplet-triplet annihilation upconversion (TTA-UC), a typical anti-Stokes luminescence technique, can generate high-energy photon emission under low-energy photon excitation, and has important application value in optical encryption, optoelectronic devices, and bioimaging. It also provides an important technical direction for expanding the optical response dimension of photonic materials. However, current research and applications of TTA-UC technology are mostly concentrated in solution systems. The development and implementation of solid-state TTA-UC materials still face many technical bottlenecks, which have become key factors restricting their application in the field of photonic materials: solid-state TTA-UC materials generally suffer from low dye loading, narrow structural color modulation range, and single optical output form, which cannot effectively synergize with the intrinsic optical properties of photonic materials; at the same time, the oxygen quenching effect in the solid environment is significant, resulting in low quantum yield of TTA-UC materials, and the luminous efficiency is difficult to meet the needs of practical applications.

[0005] In summary, current research on cholesteric liquid crystal elastomers has not yet solved the core problems of their single response dimension and poor stability when combined with luminescent materials. Furthermore, the application of triplet-triplet annihilation upconversion technology in solid-state systems is limited by bottlenecks such as low luminous efficiency and poor functional adaptability. The technical shortcomings of both types of materials have not been effectively overcome. Overall, current technologies cannot simultaneously meet the core requirements of photonic materials in practical applications, including multi-stimulus response, high stability, high density, and scalable fabrication. There is an urgent need to develop a novel multifunctional photonic material system to overcome the technical bottlenecks of existing cholesteric liquid crystal elastomers and solid-state TTA-UC materials, achieving a synergistic improvement in the optical response dimension, stability, and functionality of photonic materials. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a novel multimode display material and its preparation method, so as to overcome the shortcomings of the prior art in that it cannot simultaneously meet the requirements of multi-stimulus response, high stability, high encryption dimension and scalable preparation of photonic materials in practical applications.

[0007] The technical solution adopted by this invention to solve its technical problem is: a novel multimode display material, comprising a film-like multimode display layer, wherein the multimode display layer is formed by a composite of a CLCE matrix and an upconversion luminescent material; wherein the CLCE matrix is ​​a controllable cross-linked density elastic network with a helical superstructure, which can adjust its own pitch by controlling the concentration of chiral agent, mechanical force or heat, thereby achieving photonic bandgap adjustment, and can also control the chiral selective reflection function by controlling the chirality of the chiral agent; the upconversion luminescent material contains functionalized luminescent components capable of achieving anti-Stokes luminescence, which are combined with the CLCE matrix by covalent grafting or adaptive dispersion, and can generate upconversion luminescence under specific wavelength light excitation; the synergistic effect of the CLCE matrix and the upconversion luminescent material enables the multimode display layer to have four-dimensional orthogonal optical functions of mechanical response, thermal response, optical response and chiral selective reflection.

[0008] As a further improvement of the present invention, the CLCE matrix is ​​prepared by a one-step method or a two-step method; the raw materials for the one-step method include liquid crystal monomers, chiral dopants, crosslinking agents, chain extenders, photoinitiators, and catalysts; the raw materials for the two-step method include liquid crystal oligomers, liquid crystal monomers, chiral dopants, and photoinitiators; wherein the liquid crystal oligomers are obtained by an addition reaction between liquid crystal monomers and chain extenders.

[0009] As a further improvement of the present invention, the molar ratio of the liquid crystal oligomer to the liquid crystal monomer is 1:(1.8-2.3); and the concentration of the chiral dopant is 1.0wt%-4.0wt%.

[0010] As a further improvement of the present invention, the liquid crystal monomer is an acrylate liquid crystal monomer; the chain extender is any one of EDDET, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,8-octanedithiol, and 1,4-benzenedithiol; the chiral dopant is any one or a combination of LC756, SV6N, and S5011; and the photoinitiator is any one or a combination of Irgacure651, DMPA, and Irgacure819.

[0011] As a further improvement of the present invention, the upconversion luminescent material is a triplet-triplet annihilation upconversion material or a nano-upconversion material; the triplet-triplet annihilation upconversion material contains an annihilation agent and a sensitizer, and the nano-upconversion material has a core-shell structure and is equipped with surface modification components.

[0012] As a further improvement of the present invention, the annihilation agent is DPA, DPA1 or DPA2, wherein the molecular ends of DPA1 and DPA2 both have acrylate double bonds, and DPA1 / DPA2 are grafted onto the CLCE matrix through the acrylate double bonds. The sensitizer is physically doped into the CLCE matrix and forms an energy transfer pair with the annihilation agent that can achieve anti-Stokes luminescence.

[0013] As a further improvement of the present invention, the core layer of the nano-upconversion material contains luminescent central ions, wherein the luminescent central ions are selected from Yb. 3+ Tm 3+ Ho 3+ At least one of the following; the shell of the nano-upconversion material comprises a sensitized ion or a non-radiative relaxation suppression matrix, wherein the sensitized ion is selected from Nd... 3+ Yb 3+ At least one of the following, wherein the nonradiative relaxation suppression matrix is ​​a fluoride matrix; and the surface modification component of the nano-upconversion material is selected from at least one of amphiphilic ligands and functionalized dyes.

[0014] This invention also provides a method for preparing a novel multimode display material, comprising the following steps: S1, Mix the components of the CLCE matrix according to the specified ratio, and obtain the CLCE matrix precursor after uniform dispersion treatment; S2, Prepare an upconversion luminescent material, wherein the upconversion luminescent material is a triplet-triplet annihilation upconversion material or a nano-upconversion material; S3, the CLCE matrix precursor is mixed with the upconversion luminescent material and dispersed to obtain a uniform composite precursor; S4, the composite precursor is subjected to molding process to obtain the novel multimode display material as described above.

[0015] As a further improvement of the present invention, step S4 is performed in any of the following ways: a. After removing the solvent from the composite precursor, it is injected into a molding mold, and then a polymerization reaction is initiated by UV light. After peeling, a film-like multimode display layer is obtained. b. The composite precursor is prepared into a printing ink, which is then deposited onto an elastic substrate via a spraying process and a mask. After the solvent evaporates, a curing reaction is initiated by UV light to obtain a patterned multi-mode display layer.

[0016] The beneficial effects of this invention are as follows: This invention provides a novel multimode display material and its preparation method. By compositing a CLCE matrix with an upconversion luminescent material to form a film-like multimode display layer, the controllable cross-linked density elastic network characteristics of the CLCE matrix with its helical superstructure are utilized to achieve reversible control of the photonic bandgap and chiral selective reflection function under mechanical and thermal effects. At the same time, through the covalent grafting or adaptive dispersion of the functionalized luminescent components of the upconversion luminescent material with the CLCE matrix, anti-Stokes luminescence under specific wavelength light excitation is achieved. The synergistic effect of the two endows the multimode display layer with four-dimensional orthogonal optical functions of mechanical response, thermal response, optical response, and chiral selective reflection, effectively solving the technical bottleneck of existing photonic materials with single response dimension and low functional integration. It significantly improves the material's anti-cracking ability and adaptability in scenarios such as optical encryption and dynamic information display. At the same time, it is compatible with spray printing technology and can prepare complex patterned thin films. Multimode information encryption can be achieved through stimulation combination, enhancing practicality and meeting the core requirements of photonic materials in practical applications for multi-stimulus response, high stability, high encryption dimension, and scalable preparation. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the steps of the preparation method of the novel multimode display material of the present invention; Figure 2 This is a diagram showing the complete synthetic route and chemical equations for DPA2 in this invention. Figure 3 This is a diagram showing the color change of the novel multimode display material of the present invention, which initially reflects red, to blue after mechanical stretching. Figure 4 A multi-angle view of a multimode display layer with an initial red reflection obtained by spraying with the printing ink prepared in this invention; Figure 5 This is a schematic diagram illustrating the synthesis mechanism of the novel multimode display material of the present invention; Figure 6 This is a process flow diagram of the molding process of the prepolymer in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram illustrating the optical function, mechanochromatic color-release recovery function, and circular polarization function of the novel multimode display material of this invention. Figure 8The present invention utilizes the photoelectric function, the force-induced color change-release recovery function, and the circular polarization function to prepare an elastomer, which is then combined after spraying to form an encrypted pattern. Figure 9 This is a chemical equation diagram of the complete synthetic route of DPA1 in this invention. Detailed Implementation

[0019] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0023] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0024] Example 1

[0025] This invention provides a novel multimode display material, comprising a film-like multimode display layer formed by a composite of a CLCE matrix and an upconversion luminescent material. The CLCE matrix is ​​a controllable cross-linked density elastic network with a helical superstructure, capable of adjusting its pitch through chiral agent concentration, mechanical force, or heat, thereby achieving photon bandgap modulation. It also allows for chiral selective reflection control through the chirality of the chiral agent. The upconversion luminescent material contains functionalized luminescent components capable of anti-Stokes luminescence. These functionalized luminescent components are combined with the CLCE matrix through covalent grafting or adaptive dispersion, and can be excited by specific wavelengths of light. It generates upconversion luminescence; the synergistic effect of the CLCE matrix and the upconversion luminescent material enables the multimode display layer to possess four-dimensional orthogonal optical functions of mechanical response, thermal response, optical response and chiral selective reflection. This effectively solves the technical bottleneck of existing photonic materials with single response dimension and low functional integration, significantly improving the material's anti-cracking ability and adaptability in scenarios such as optical encryption and dynamic information display. At the same time, it is compatible with spray printing technology and can prepare complex patterned thin films. Multimode information encryption can be achieved through stimulation combination, enhancing practicality and meeting the core requirements of photonic materials in practical applications for multi-stimulus response, high stability, high encryption dimension and scalable preparation.

[0026] In this invention, the CLCE matrix can be prepared by a one-step or two-step method. The raw materials for the one-step method include liquid crystal monomers, chiral dopants, crosslinking agents, chain extenders, photoinitiators, and catalysts. The raw materials for the two-step method include liquid crystal oligomers, liquid crystal monomers, chiral dopants, and photoinitiators. The liquid crystal oligomers are obtained by an addition reaction between the liquid crystal monomers and the chain extender. For a detailed description of the preparation process, please refer to Example 2 below. The design of these two preparation methods provides flexibility in CLCE matrix preparation. The one-step method offers advantages such as simple process, high preparation efficiency, and no need for prior synthesis of liquid crystal oligomers, thus reducing preparation costs. The two-step method allows for precise control of the elastic network structure and helical superstructure of the CLCE matrix through prior synthesis of liquid crystal oligomers, ensuring the stability of its mechanical / thermal response properties and chiral selective reflectivity. The raw material composition of both methods closely matches the performance requirements of the CLCE matrix, laying a good foundation for subsequent effective composite with upconversion luminescent materials and ensuring the structural integrity and synergistic optical performance of the composite material.

[0027] In the two-step preparation of the CLCE matrix, the molar ratio of liquid crystal oligomer to liquid crystal monomer is 1:(1.8-2.3), preferably 1:2. This molar ratio range can precisely control the crosslinking density and elastic network structure of the CLCE matrix, avoiding the problems of the matrix being too brittle and unresponsive due to an excessively high proportion of liquid crystal oligomer, or the matrix being insufficiently crosslinked and unstable in the helical structure due to an excessively low proportion. At the same time, it ensures that the elasticity and optical properties of the CLCE matrix reach the optimal balance.

[0028] Preferably, the concentration of the chiral dopant is 1.0wt%-4.0wt%, at which the photonic bandgap wavelength of the CLCE matrix covers the red-blue visible spectrum.

[0029] Optionally, the liquid crystal monomer is an acrylate liquid crystal monomer, such as RM82 or RM257; the chain extender is any one of EDDET (dithiol), 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,8-octanedithiol, and 1,4-benzenedithiol; the chiral dopant is any one or a combination of LC756, SV6N, and S5011; and the photoinitiator is any one or a combination of Irgacure651, DMPA, and Irgacure819.

[0030] In this invention, the upconversion luminescent material is either a TTA-UC material or a nano-upconversion material. The functionalized luminescent component of the TTA-UC material includes an annihilator and a sensitizer. The nano-upconversion material has a core-shell structure and surface-modified components. Both upconversion luminescent materials can effectively bind to the CLCE matrix to achieve photoresponsive upconversion luminescence. In synergy with the mechanical / thermal response and chiral selective reflection function of the CLCE matrix, they further enhance the four-dimensional orthogonal optical function of the multimode display material and expand its application range. When the TTA-UC material is selected as the upconversion luminescent material, the annihilator can optionally be DPA, DPA1, or DPA2.

[0031] DPA (9,10-diphenylanthracene) is a conventional material. The molecular structure of DPA1 is as follows: The molecular structure of DPA2 is as follows: n represents the number of carbon chains, which is any integer from 1 to 15.

[0032] DPA1 has one acrylate double bond at its molecule's end, while DPA2 has two acrylate double bonds at its molecule's end. DPA1 / DPA2 are grafted onto the CLCE matrix via covalent bonding through these acrylate double bonds. A sensitizer (such as PdOEP) is physically doped into the CLCE matrix, forming an energy transfer pair with DPA1 / DPA2 capable of achieving anti-Stokes luminescence. This invention employs a composite strategy of covalent bonding of the annihilator and physical doping of the sensitizer, which solves the stability problem of physical doping while ensuring energy transfer efficiency during the TTA-UC process, thus balancing material uniformity and optical performance.

[0033] When nano-upconversion materials are selected as the upconversion luminescent materials, the core layer of the nano-upconversion materials contains luminescent central ions, which are selected from Yb. 3+ Tm 3+Ho 3+ At least one of the following; the shell of the nano-upconversion material contains sensitized ions or a non-radiative relaxation suppression matrix, wherein the sensitized ions are selected from Nd... 3+ Yb 3+ At least one of the following, the non-radiative relaxation inhibition matrix is ​​a fluoride matrix; the surface modification component of the nano-upconversion material is selected from at least one of amphiphilic ligands and functionalized dyes.

[0034] Example 2

[0035] See Figure 1 The present invention also provides a method for preparing a novel multimode display material, comprising the following steps S1 to S4.

[0036] S1, the components of the CLCE matrix are mixed according to the specified ratio and then dispersed uniformly to obtain the CLCE matrix precursor. In this embodiment, the CLCE matrix is ​​prepared using a two-step method.

[0037] See Figure 5 Specifically, the acrylate liquid crystal monomer RM82 and EDDET (EDDET is the primary chain extender in the reaction, which can be replaced by various dithiols, such as 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,8-octanedithiol, 1,4-benzenedithiol, etc.) are first dissolved in dichloromethane, and DBU catalyst is added and stirred at room temperature for 24 hours. After acid washing, drying and vacuum distillation, thiol-terminated EDDET-RM82 oligomers are obtained.

[0038] In this embodiment, the mass of RM82 is 10g; the mass of EDDET is 5g-6g, preferably 5.4g, the value of which determines the degree of crosslinking of the oligomer; the more EDDER, the higher the degree of crosslinking; dichloromethane is 90ml-110ml, preferably 100ml; and DBU is 35ml-45ml, preferably 40ml.

[0039] Subsequently, EDDET-RM82 oligomer, acrylate liquid crystal monomer RM82, chiral dopant, and photoinitiator were dissolved in dichloromethane to obtain the CLCE matrix precursor. EDDET-RM82 oligomer and acrylate liquid crystal monomer RM82 serve as the nematic liquid crystal host. The addition of the chiral dopant transforms the nematic liquid crystal into a chiral nematic phase, providing it with vibrant reflective structural colors. The chiral dopant controls the helical direction, achieving selective reflection of left / right circularly polarized light. In this embodiment, LC756 was specifically selected as the chiral dopant. The photoinitiator is used to facilitate the ultraviolet polymerization of the elastomer.

[0040] In this embodiment, the proportions of each component are as follows: 0.5g of EDDET-RM82; 0.18g-0.22g of RM82, preferably 0.2g; 0.0192g of photoinitiator; 2ml of dichloromethane; and 2.6wt%-3.2wt% and 0.025g-0.034g of LC756 (reflection structure color from red to blue). For example, if the mass of LC756 is 0.026g, the photonic bandgap wavelength of the prepared cholesteric liquid crystal elastomer is 680nm; if the mass of LC756 is changed to 0.03g, the photonic bandgap wavelength is 590nm; and if the mass of LC756 is changed to 0.034g, the photonic bandgap wavelength is 490nm.

[0041] S2, prepare upconversion luminescent material, the upconversion luminescent material is TTA-UC material, its annihilation agent is DPA2 and its sensitizer is PdOEP.

[0042] DPA2 is prepared from 9,10-dibromoanthracene via Suzuki coupling, reduction, etherification, deprotection, and esterification to form two acrylate double bonds at the molecule's end that can be covalently grafted onto the CLCE matrix.

[0043] like Figure 2 As shown, the specific preparation process of DPA2 is as follows: First, 9,10-dibromoanthracene (10.0 mmol), 4-formylphenylboronic acid (25.0 mmol), 2.0 M Na2CO3 aqueous solution, and tetra(triphenylphosphine)palladium (Pd(PPh3)4, 0.3 mmol) were added to a solvent consisting of tetrahydrofuran (THF) and toluene (1:1, 25 mL). The reaction was heated at 85 °C for 12 h under a nitrogen atmosphere. After cooling to room temperature, sodium borohydride (NaBH4, 10.0 mmol) was added and stirring was continued for 5 h. The reaction was quenched with ammonium chloride (NH4Cl), diluted with water, extracted three times with diethyl ether, and the organic phase was washed with water and saturated NaCl, dried over anhydrous MgSO4, and concentrated by rotary evaporation under reduced pressure. Next, at 0°C, intermediate 1 and NaH were dissolved in THF, silane reagent was added dropwise and stirred at room temperature for 8 hours, then TBAF was added and stirring was continued for 4 hours. The organic phase was washed with 5% sodium metabisulfite solution and water, dried with anhydrous MgSO4, and concentrated by rotary evaporation under reduced pressure. Finally, methacryloyl chloride was added dropwise under a nitrogen atmosphere at 0°C (all added in 5 min), and the mixture was stirred at room temperature for 6 h. The organic phase was washed with sodium bicarbonate aqueous solution and saturated NaCl, dried over anhydrous MgSO4, and concentrated by rotary evaporation under reduced pressure to obtain DPA2.

[0044] It should be noted that the sensitizer PdOEP used in this embodiment is a conventional material.

[0045] S3, DPA2 and PdOEP are mixed with the CLCE matrix precursor prepared in step S1, stirred and sonicated for 5 minutes to obtain a uniform composite precursor, and the solvent is removed by heating to obtain a transparent viscous prepolymer.

[0046] In this step, DPA2 undergoes chain extension on the elastomer matrix via an addition reaction. It contains acrylate double bonds that can participate in photopolymerization addition reactions and is compatible with RM82 and the crosslinking system of the cholesteric liquid crystal system. The DPA2 molecule has two acrylate double bonds (-CH=CH-COO-) at its terminal ends. These double bonds are carbon-carbon unsaturated double bonds, typical active sites for photopolymerization addition reactions. Under the action of a photoinitiator, they can undergo free radical addition polymerization, connecting with the active groups of RM82 and the crosslinking agent in the cholesteric liquid crystal system, thus achieving grafting. PdOEP is physically doped into the CLCE matrix and forms an energy transfer pair with DPA2. This technical solution effectively solves the existing problems of weak bonding between luminescent materials and the CLCE matrix, easy phase separation, and fluorescence quenching. The covalent grafting method can ensure that DPA2 and the CLCE matrix form a stable chemical bond, significantly improving the optical stability and service life of the composite material. The energy transfer pair formed by PdOEP and DPA2 can efficiently achieve anti-Stokes luminescence, reduce energy loss, and improve upconversion luminescence efficiency. At the same time, the physically doped PdOEP is uniformly dispersed and will not destroy the helical superstructure of the CLCE matrix, ensuring that the mechanical / thermal response performance and chiral selective reflectivity of the CLCE matrix are not affected. This achieves synergistic compatibility between the upconversion luminescence function and the intrinsic optical function of the CLCE matrix, further improving the photoresponse performance and application reliability of multimode display materials.

[0047] In this embodiment, the optimal dye concentration of PdOEP is 0.03wt%, the optimal dye concentration of DPA2 is 2.0wt%, the mass of DPA2 is 0.01-0.015g, preferably 0.012g, and the mass of PdOEP is 0.001-0.005g, preferably 0.001g.

[0048] like Figure 6 As shown, in step S4, the prepolymer is subjected to molding treatment to obtain the novel multimode display material as described in Example 1.

[0049] Specifically, the prepolymer prepared by S3 is injected into a glass cell (thickness controlled by a 20μm gasket), and uniaxial shearing induces mesocrystalline orientation. This process transforms the disordered cholesteric liquid crystal into an overall ordered structure through frictional orientation, resulting in a vibrant reflective structural color. This can be achieved by fixing the glass cell containing the prepolymer on a friction machine equipped with rollers, and rubbing the upper glass back and forth along a uniaxial direction until the reflective structural color appears. (At 70mW-cm...) -2Polymerize under UV light for 120 seconds to lock the helical superstructure, and obtain a film-like multimode display layer after peeling.

[0050] The novel multimode display material obtained by this invention possesses the following four-dimensional orthogonal optical response: 1) Chiral selective reflection: Selective reflection of left / right circularly polarized light is achieved by controlling the helical direction through chiral dopants; 2) Thermal response: The thermal expansion of the cross-linked network dominates the pitch change. The CLCE matrix film exhibits a red shift opposite to that of the prepolymer (λ shift of 156nm at 30℃-80℃), and has thermally reset shape memory. 3) Mechanical response: such as Figure 3 As shown, tensile strain (0-200%) causes CLCE pitch to shrink and PBG to blue shift (maximum 259nm), thus achieving dynamic control of structural color. 4) Photoresponse: DPA2 emits blue light under UV excitation, and TTA-UC emits violet-blue light under 532nm laser excitation.

[0051] Figure 7 The diagram illustrates the optical function, mechanochromatic color-release recovery function, and circular polarization function of the novel multimode display material (UC@CLCE) prepared according to this invention. UC@CLCE with an initial red reflection wavelength, due to the use of a right-handed chiral agent, filters out stray light when passing through a right-handed circular polarizer, resulting in a more vibrant red reflection. However, when passing through a left-handed circular polarizer, due to chiral reflection mismatch, it appears black (unstructured color). Under ultraviolet light irradiation, UC@CLCE emits blue fluorescence. Under 532nm laser irradiation, and after filtering out strong green light with a 532nm filter, UC@CLCE emits strong violet upconversion light. Under stretching conditions, due to the change in pitch of UC@CLCE, the reflection wavelength of CLCE undergoes a blue shift. Simultaneously, after release, due to the elasticity of UC@CLCE, it springs back, the pitch recovers, and UC@CLCE undergoes a red shift again.

[0052] like Figure 8As shown, the five-pointed star encryption pattern is composed of four different CLCEs (a. left-handed UC@CLCE, b. right-handed UC@CLCE, c. right-handed DPA2@CLCE, d. right-handed CLCE), while the number "8" encryption pattern is composed of five different CLCEs (a. right-handed CLCE with infrared reflection, b. left-handed CLCE with green reflection, c. right-handed CLCE with green reflection, d. right-handed DPA2@CLCE with green reflection, e. right-handed UC@CLCE with red reflection). Under natural light, only the surrounding pattern of the encrypted pattern with the five stars is visible. After stretching, the five stars in the center appear (the initial structural color is in infrared and invisible to the human eye, but becomes visible after stretching). Under a left-handed circular polarizer, only the left-handed pattern is visible, while the right-handed reflection is enhanced. Under a right-handed circular polarizer, only the right-handed pattern is visible. When using ultraviolet excitation, only CLCEs containing DPA2 will exhibit blue light. When using 532nm laser excitation, only UC@CLCEs will exhibit violet upconversion luminescence.

[0053] In addition, the present invention also conducted performance tests on the novel multimode display material prepared in this embodiment, and the results are as follows: 1) Excellent mechanical properties: The film elongation at break reaches 197%-213%, far exceeding the existing luminescent CLCE materials (80%-110%). PBG has a maximum blue shift of 259nm at 200% strain and a wide range of structural color modulation. 2) Excellent stability: DPA2 covalent bonding avoids phase separation, and the sulfide groups of the CLCE network have oxygen scavenging ability. The novel multimode display material still retains 6% UC luminescence intensity after 100 hours of air exposure, which is far superior to the solution system (complete quenching after 3.5 hours). 3) High-efficiency TTA-UC performance: The excitation power threshold is as low as 46 Mw / cm, which is lower than the existing liquid crystal-based TTA-UC system (83-254 Mw / cm), and the maximum UC quantum yield is 4.9%.

[0054] In addition, in step S2 of this invention, the sensitizer of the upconversion luminescent material can also be pyrene-tetracyanobenzene, and the annihilation agent can be 9,10-diphenylanthracene (DPA), which can upconvert 532nm low-energy photons to 430nm high-energy photons; or the sensitizer can be tris(2-phenylpyridine)iridium, and the annihilation agent can be bis(phenylethynyl)benzene, which can achieve visible light to ultraviolet light (380nm) conversion; or the sensitizer can be heptamethrin, and the annihilation agent can be rubrene, which can achieve 830nm near-infrared light excitation to 557nm visible light emission conversion.

[0055] Example 3

[0056] The difference between this embodiment and Embodiment 2 is that the molding process of the prepolymer in step S4 is different. The specific details of this embodiment are as follows: Printing ink was prepared by dissolving EDDET-RM82, RM82, a chiral dopant, a photoinitiator, and dyes (DPA2 and PdOEP) in toluene. The component ratios of the printing ink were as follows: 0.5 g of EDDET-RM82; 0.18 g-0.22 g of RM82, preferably 0.2 g; 0.025 g-0.034 g of LC756 (reflective structural colors from red to blue); 0.0192 g of the photoinitiator; and 2 ml of toluene. The dye concentration of PdOEP was 0.03 wt%, and the dye concentration of DPA2 was 2.0 wt%. The mass of DPA2 was 0.01-0.015 g, preferably 0.012 g; and the mass of PdOEP was 0.001-0.005 g, preferably 0.001 g.

[0057] In this process, the color development method of the cholesteric liquid crystal differs from that used in Example 2, where unidirectional shear-induced mesocrystalline orientation is achieved. Instead, the slow evaporation of toluene drives the liquid crystal molecules to align in an orderly manner, thereby forming a vibrant reflective structural color. The layer is deposited on an elastic substrate (which can be any hydrophilic substrate) via a spraying process (8 mg / s spraying rate, 0.2 MPa pressure). After solvent evaporation at room temperature, it is irradiated with 50 Mw / cm UV light for 5 minutes to obtain a patterned multimode display layer.

[0058] Figure 4 The characteristics of the reflective structural color change of the patterned multimode display layer under different observation angles are intuitively presented: at a normal viewing angle perpendicular to the surface of the multimode display layer, the patterned area presents a bright and uniform red reflective structural color, which is the initial reflective color of the multimode display layer; when the observation angle shifts from the normal viewing angle to the oblique angle (30°, 45°, 60°, etc.), the reflective structural color of the patterned area gradually changes with the change of observation angle, transitioning from the initial red to orange-red, orange-yellow and other hues. The visual effect of the reflective color under different oblique observation angles is significantly different, and the edges of the patterned area are clear and regular, without blurring or color overflow. The unpatterned area of ​​the elastic substrate has no obvious structural color reflection, forming a sharp visual contrast with the patterned area.

[0059] Example 4

[0060] The difference between this embodiment and Embodiment 2 is that the CLCE matrix in step S1 is prepared using a one-step method, the specific preparation method of which is as follows: First, RM257: 71.2 wt.%, LC756: 3.2 wt.%-4.2 wt.% (reflection colors: red 3.2 wt.%, green 3.8 wt.%, blue 4.2 wt.%), crosslinking agent (PETMP): 4.8 wt.%, chain extender (EDDET): 18.5 wt.%, photoinitiator (Irgacure651): 0.55 wt.%, catalyst (DPA): 0.25 wt.%, and solvent: dichloromethane (CH2Cl2) are mixed thoroughly to obtain the CLCE matrix precursor.

[0061] The dyes (DPA2 and PdOEP) of the TTA-UC material prepared in S2 were mixed with the CLCE matrix precursor. The mixture was then transferred to a clean glass petri dish and left open at room temperature for 12 hours to allow the dichloromethane to evaporate completely, forming a uniform precursor film. Finally, the precursor film was irradiated under 365nm ultraviolet light (power ≈50mW / cm²) for 10 minutes (room temperature 25°C) to trigger the photopolymerization reaction, thereby obtaining the novel multimode display material as described in Example 1.

[0062] Example 5

[0063] In this embodiment, the CLCE matrix in step S1 is prepared using a one-step method, but it differs from that in Example 4. The specific preparation method is as follows: Using acrylate liquid crystal monomers (RM82 or RM257) as the matrix, dithiol chain extenders (such as EDDET, EGBTG, BPAT) and chiral dopants (such as LC756, RIA) are added. Functional units (such as DPA2 luminescent monomers, SPBMs pigment units, and KH590 modified ATO nanoparticles) are added as needed. At the same time, photoinitiators (such as I651, I819) and amine catalysts (such as butylamine) are added. The mixture is stirred at 50°C for 20 min and ultrasonically dispersed to obtain a uniform CLCE matrix precursor.

[0064] The dyes (DPA2 and PdOEP) of the TTA-UC material prepared in S2 were mixed with the CLCE matrix precursor. The mixture was cast between two glass substrates and heated at 50°C for 24 hours. A Michael addition reaction occurred between the thiol groups of dithiol and the acrylate double bonds of the liquid crystal monomers, forming a linear prepolymer. This prepolymer laid the foundation for subsequent crosslinking and ensured the ordered arrangement of the liquid crystal phase. The linear prepolymer was irradiated with light of a specific wavelength (e.g., 520 nm, ultraviolet light) for 30 minutes. The photoinitiator triggered free radical addition polymerization of the remaining acrylate double bonds in the system (including the double bonds of liquid crystal monomers and functional monomers such as DPA2), forming a three-dimensional crosslinked polymer elastomer network. The crosslinked film was peeled off from the glass substrate to obtain the novel multimode display material as described in Example 1.

[0065] Example 6

[0066] The difference between this embodiment and Embodiment 2 is that the upconversion luminescent material in step S2 is a nano-upconversion material.

[0067] The core layer of the nano-upconversion material is NaYF4:Yb,Tm (Yb 3+ As a sensitizer, Tm 3+ (As the luminescent center), the shell of the nano-upconversion material is NaYF4:Yb,Nd (Nd 3+ The sensitization agent was synthesized via high-temperature thermal decomposition; the surface was modified with the near-infrared dye IR 61-BF (a heptamethrin derivative containing a difluorophenyl group) and the amphiphilic ligand DSPE-PEG. 3+ With Yb 3+ By synergistically absorbing 808nm near-infrared light, the dye IR 61-BF enhances the energy transfer from dye to nanocrystals, thereby increasing the upconversion luminescence intensity in the aqueous phase by 167.1 times.

[0068] In addition, this invention also provides another nano-upconversion material, the core layer of which is NaGdF4:Ho (Ho 3+ It has a single luminescent center (doping concentration ~20 nm), and the shell is NaYF4 (to suppress nonradiative relaxation); based on Ho 3+ The 5I7 and 5I6 dual intermediate energy levels were used to construct a "parallel photonic avalanche (PPA)" mechanism. Under continuous laser excitation at 965nm, multi-color upconversion of red light (645nm, 5F5→5I8), green light (540nm, 5S2 / 5F4→5I8), and blue light (485nm, 5F2,3 / 5K8→5I8) was achieved simultaneously.

[0069] Example 7

[0070] The difference between this embodiment and Embodiment 2 is that in step S2, the annihilation agent of the upconversion luminescent material is DPA1.

[0071] like Figure 9 As shown, the specific preparation process of DPA1 is as follows: First, a coupling reaction (8→9) is carried out; the bromoaryl compound (8) and p-formylphenylboronic acid ((HO2)B-C6H4-CHO) are reacted in a THF / toluene mixed solvent at 85°C with Pd(PPh3)4 as a catalyst and Na2CO3 as a base.

[0072] Next, NaBH4 (sodium borohydride) was used as a reducing agent. Sodium borohydride selectively reduced the aldehyde group (-CHO) to the primary alcohol (-CH2OH) without affecting other unsaturated bonds in the molecule, thus obtaining diaryl methanol (10).

[0073] Subsequently, diaryl methanol (10) was treated with NaH (sodium hydride); sodium hydride, as a strong base, deprotonates the hydroxyl group (-OH) of the alcohol to generate a more nucleophilic sodium alkoxide (-ONa). ω-haloalkyl ethers were then added. Figure 9 The sodium alkoxide (a derivative of 1-bromo-6-hexanol) undergoes a nucleophilic substitution reaction (SN2) to couple the sodium alkoxide to a long-chain alkyl halide; the silane protecting group is removed using TBAF (tetrabutylammonium fluoride), releasing the terminal hydroxyl group.

[0074] Finally, an acylation reaction (11→12) is carried out; the diaryl ether (11) and acryloyl chloride (CH2=CH-COCl) are reacted in dichloromethane (DCM) in the presence of Et3N (triethylamine) and DMAP (4-dimethylaminopyridine) to obtain the target molecule DPA1 (12), a diaryl ether acrylate with polymerizable double bonds.

[0075] The same or similar parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments.

[0076] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A novel multimode display material, characterized in that, The multimode display layer comprises a film-like structure, wherein the multimode display layer is formed by combining a CLCE matrix and an upconversion luminescent material. The CLCE matrix is ​​a controllable cross-linked density elastic network with a helical superstructure, capable of adjusting its pitch through chiral agent concentration, mechanical force, or heat, thereby achieving photonic bandgap modulation. It also allows for chiral selective reflection control through the chirality of the chiral agent. The upconversion luminescent material contains functionalized luminescent components capable of anti-Stokes luminescence. These functionalized luminescent components are combined with the CLCE matrix through covalent grafting or adaptive dispersion and can generate upconversion luminescence under specific wavelength light excitation. The synergistic effect of the CLCE matrix and the upconversion luminescent material endows the multimode display layer with four-dimensional orthogonal optical functions: mechanical response, thermal response, optical response, and chiral selective reflection.

2. The novel multimode display material according to claim 1, characterized in that, The CLCE matrix is ​​prepared by a one-step or two-step method; the raw materials for the one-step method include liquid crystal monomers, chiral dopants, crosslinking agents, chain extenders, photoinitiators, and catalysts; the raw materials for the two-step method include liquid crystal oligomers, liquid crystal monomers, chiral dopants, and photoinitiators; wherein the liquid crystal oligomers are obtained by an addition reaction between liquid crystal monomers and chain extenders.

3. The novel multimode display material according to claim 2, characterized in that, The molar ratio of the liquid crystal oligomer to the liquid crystal monomer is 1:(1.8-2.3); the concentration of the chiral dopant is 1.0wt%-4.0wt%.

4. The novel multimode display material according to claim 2, characterized in that, The liquid crystal monomer is an acrylate-based liquid crystal monomer; the chain extender is any one of EDDET, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,8-octanedithiol, and 1,4-benzenedithiol; the chiral dopant is any one or a combination of LC756, SV6N, and S5011; and the photoinitiator is any one or a combination of Irgacure651, DMPA, and Irgacure819.

5. The novel multimode display material according to claim 1, characterized in that, The upconversion luminescent material is a triplet-triplet annihilation upconversion material or a nano-upconversion material; the triplet-triplet annihilation upconversion material contains an annihilation agent and a sensitizer, and the nano-upconversion material has a core-shell structure and surface modification components.

6. The novel multimode display material according to claim 5, characterized in that, The annihilation agent is DPA, DPA1, or DPA2, wherein both DPA1 and DPA2 have acrylate double bonds at their molecular ends. DPA1 / DPA2 are grafted onto the CLCE matrix through the acrylate double bonds. The sensitizer is physically doped into the CLCE matrix and forms an energy transfer pair with the annihilation agent that enables anti-Stokes luminescence.

7. The novel multimode display material according to claim 5, characterized in that, The core layer of the nano-upconversion material contains luminescent central ions, which are selected from Yb. 3+ Tm 3+ Ho 3+ At least one of the following; the shell of the nano-upconversion material comprises a sensitized ion or a non-radiative relaxation suppression matrix, wherein the sensitized ion is selected from Nd... 3+ Yb 3+ At least one of the following, wherein the nonradiative relaxation suppression matrix is ​​a fluoride matrix; and the surface modification component of the nano-upconversion material is selected from at least one of amphiphilic ligands and functionalized dyes.

8. A method for preparing a novel multimode display material, characterized in that, Includes the following steps: S1, Mix the components of the CLCE matrix according to the specified ratio, and obtain the CLCE matrix precursor after uniform dispersion treatment; S2, Prepare an upconversion luminescent material, wherein the upconversion luminescent material is a triplet-triplet annihilation upconversion material or a nano-upconversion material; S3, the CLCE matrix precursor is mixed with the upconversion luminescent material and dispersed to obtain a uniform composite precursor; S4, the composite precursor is subjected to molding treatment to obtain the novel multimode display material as described in any one of claims 1 to 7.

9. The method for preparing the novel multimode display material according to claim 8, characterized in that, Step S4 is performed using any of the following methods: a. After removing the solvent from the composite precursor, it is injected into a molding die, and a polymerization reaction is initiated by UV light. After peeling, a film-like multimode display layer is obtained. b. The composite precursor is prepared into a printing ink, which is then deposited onto an elastic substrate via a spraying process and a mask. After the solvent evaporates, a curing reaction is initiated by UV light to obtain a patterned multi-mode display layer.

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