Circularly polarized long afterglow material and preparation method and application thereof

Abstract

The invention discloses a circular polarization long afterglow material and a preparation method and application thereof.The circular polarization long afterglow material comprises a first film layer and a second film layer, the first film layer is a phosphorescent film, or the first film layer comprises a phosphorescent film and a fluorescent film, and the second film layer is a cholesteric liquid crystal polymer film. By utilizing radiation energy transfer and selective reflection property of the cholesteric liquid crystal polymer, the provided circular polarization long afterglow material has the dual characteristics of long service life and high glum value, and has good application value in the aspects of information encryption and anti-counterfeiting.

Description

Technical Field

[0001] The present application relates to the technical field of organic light-emitting materials, and in particular to a circularly polarized long afterglow material and a preparation method and application thereof. Background Art

[0002] Pure organic room temperature phosphorescence (RTP) has flourished in the fields of bioimaging, sensing and anti-counterfeiting due to its large Stokes shift, long emission lifetime and low toxicity. Ultra-long RTP materials have an afterglow visible to the naked eye, which broadens the storable dimension of optical signals. Unlike linearly polarized light, circularly polarized luminescence (CPL) is characterized by a circular rotation of the electric field vector around the propagation axis, providing higher resolution and signal fidelity in optical imaging and communication systems.

[0003] The organic ultralong-circularlypolarized luminescence (OU-CPL) material, which combines RTP and CPL, can provide stable polarized light signals for a long time due to its time-varying afterglow and polarization properties. This integration further expands the size of the luminescent signal and enhances the stability and reliability of the stored information. These properties help expand its value in the fields of information storage and anti-counterfeiting measures. Summary of the invention

[0004] The present application provides a circularly polarized long afterglow material and a preparation method and application thereof, which can utilize radiation energy transfer and the selective reflection properties of cholesteric liquid crystal polymers to obtain a long life and high g lum Pure organic circularly polarized long afterglow materials with high value.

[0005] In a first aspect, the present application provides a circularly polarized long afterglow material, comprising: a first film layer and a second film layer, wherein the first film layer is a phosphorescent film, or the first film layer comprises a phosphorescent film and a fluorescent film, and the second film layer is a cholesteric liquid crystal polymer film.

[0006] In some embodiments, the phosphorescent film includes a first guest material and a first host material, the first guest material is an organic aromatic molecule, and the first host material is a polymer matrix material having rigidity.

[0007] In some embodiments, the fluorescent film includes a second guest material and a second host material, the absorption spectrum of the second guest material has spectral overlap with the emission spectrum of the phosphorescent film, and the second guest material is a fluorescent molecule with a photoluminescence quantum yield of more than 50%, and the second host material is a film-forming polymer matrix.

[0008] In some embodiments, the first host material includes at least one of polyvinyl alcohol, polyacrylamide, polymethyl methacrylate, polyvinyl butyral resin and polyacrylonitrile; the second host material can be at least one of polymethyl methacrylate, polyvinyl butyral, polyacrylonitrile, poly(ε-caprolactone), polyethylene-vinyl acetate copolymer, and polyacrylic acid; the second guest material includes at least one of 9,10-bis(phenylethynyl)anthracene, sodium fluorescein, 4,7-di(2-thienyl)-2,1,3-benzothiadiazole and Nile red.

[0009] In some embodiments, the circularly polarized long afterglow material has an ultra-long afterglow from ultraviolet to near infrared, and the afterglow lifetime is about 10 -1 Up to 10 2 s range, the circularly polarized luminescence asymmetry factor is 10 0 Order of magnitude.

[0010] In some embodiments, the cholesteric liquid crystal polymer film has a selective reflection property for circularly polarized light in the wavelength range from ultraviolet to near infrared.

[0011] In a second aspect, the present application provides a method for preparing a circularly polarized long afterglow material, comprising the following steps:

[0012] (1) preparing a first film layer, wherein the first film layer is a phosphorescent film, or the first film layer includes a phosphorescent film and a fluorescent film, wherein the phosphorescent film is prepared by dissolving a first guest material and a first host material in a first solvent, fully mixing them, evaporating the first solvent and drying to obtain the phosphorescent film, and the fluorescent film is prepared by dissolving a second guest material and a second host material in a second solvent, fully mixing them, evaporating the second solvent and drying to obtain the fluorescent film;

[0013] (2) preparing a second film layer, comprising dissolving a liquid crystal monomer, a photoinitiator and a chiral dopant in a third solvent, fully mixing the mixture, and polymerizing the mixture under ultraviolet light to obtain a cholesteric liquid crystal polymer film;

[0014] (3) Assembling the first film layer and the second film layer to obtain the circularly polarized long afterglow material.

[0015] In some embodiments, in step (3), the chiral dopant is R-5011 or S-5011, and the amount of the chiral dopant added is 1.9%-2.9% by mass.

[0016] In some embodiments, the first solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran; the second solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran; and the third solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran.

[0017] In a third aspect, the present application provides an application of a circularly polarized long afterglow material in information encryption and anti-counterfeiting materials.

[0018] This application has the following beneficial effects:

[0019] (1) The circularly polarized long afterglow material provided by the present application utilizes the radiation energy transfer and the selective reflection mechanism of cholesteric liquid crystal, and has the dual characteristics of time-dependent afterglow and polarization signal. It is easy to prepare, has reasonable cost, strong universality, and a large control space.

[0020] (2) The circularly polarized long afterglow material provided in this application has good circularly polarized afterglow performance, has ultra-long afterglow from ultraviolet to near infrared, and the afterglow life is 10 -1 Up to 10 2 s range, the circularly polarized luminescence asymmetry factor (g lum value) is 10 0 Order of magnitude;

[0021] (3) The order of the first film layer and the second film layer of the circularly polarized long afterglow material provided in the present application, as well as the order of the phosphorescent film and the fluorescent film inside the first film layer can be adjusted, so that the wavelength and direction of the circularly polarized light can be conveniently controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other dyes or similar matrices can be used without creative work to obtain other drawings based on these drawings.

[0023] Figure 1 is the circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 1;

[0024] Figure 2 is the lifetime decay curve of the circularly polarized long afterglow material prepared in Example 1 at 475 nm;

[0025] Figure 3 is the circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 2;

[0026] Figure 4 is the lifetime decay curve of the circularly polarized long afterglow material prepared in Example 2 at 500 nm;

[0027] Figure 5 is the circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 3;

[0028] Figure 6 is the lifetime decay curve of the circularly polarized long afterglow material prepared in Example 3 at 520 nm;

[0029] Figure 7 is the circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 4;

[0030] Figure 8 is the lifetime decay curve of the circularly polarized long afterglow material prepared in Example 4 at 560 nm;

[0031] Fig. 9 is the circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 5;

[0032] Fig.10 is the lifetime decay curve of the circularly polarized long afterglow material prepared in Example 5 at 620 nm;

[0033] Fig.11 Schematic diagram of the application of the circularly polarized long afterglow material prepared in Example 6 in information encryption and anti-counterfeiting;

[0034] Fig.12 is a schematic diagram of the arrangement order of the distances between different film layers and the excitation source from near to far in Example 7;

[0035] Fig.13 is the circularly polarized emission spectrum of the circularly polarized long afterglow material of system (I) in Example 7;

[0036] Fig.14 is the circularly polarized emission spectrum of the circularly polarized long afterglow material of system (II) in Example 7;

[0037] Fig.15 This is the circularly polarized emission spectrum of the circularly polarized long afterglow material of system (III) in Example 7. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0039] In a first aspect, an embodiment of the present application provides a circularly polarized long afterglow material, comprising: a first film layer and a second film layer, wherein the first film layer is a phosphorescent film, or the first film layer comprises a phosphorescent film and a fluorescent film, and the second film layer is a cholesteric liquid crystal polymer film.

[0040] When the first film layer is a phosphorescent film, the circularly polarized long afterglow material has a two-layer film structure; when the first film layer includes both a phosphorescent film and a fluorescent film, the circularly polarized long afterglow material has a three-layer film structure.

[0041] In the embodiment of the present application, the first film layer is a phosphorescent film; or, the first film layer includes a phosphorescent film and a fluorescent film. The circularly polarized long afterglow material provided in the embodiment of the present application can be a two-layer film structure or a three-layer film structure. When the circularly polarized long afterglow material is a two-layer film structure, the first film layer can be a phosphorescent film, and the second film layer is a cholesteric liquid crystal polymer film. When the circularly polarized long afterglow material is a three-layer film structure, the first film layer includes both a phosphorescent film and a fluorescent film, and the second film layer is a cholesteric liquid crystal polymer film.

[0042] In the embodiment of the present application, the phosphorescent film includes a first guest material and a first host material, the first guest material is an organic aromatic molecule, and the first host material is a rigid polymer matrix material. When a rigid polymer matrix material is used as the first host material, the rigid environment is conducive to suppressing the non-radiative transition of triplet excitons, which is conducive to achieving efficient phosphorescent emission.

[0043] The phosphorescent film provided in the embodiment of the present application may be a phosphorescent film with long afterglow emission characteristics, which may include organic aromatic molecules as guest materials and a rigid polymer matrix as a host material. The chemical structural formula of the organic aromatic molecules may be as shown in Formula (I-1) to Formula (I-9):

[0044]

[0045] Among them, R can be at least one of -H, -CH3, -NH2, -COOH, and -B(OH)2.

[0046] The first main material may be a rigid polymer such as polyvinyl alcohol, polyacrylamide, polymethyl methacrylate, polyvinyl butyral resin, polyacrylonitrile, etc.

[0047] In an embodiment of the present application, the fluorescent film includes a second guest material and a second host material, the absorption spectrum of the second guest material has spectral overlap with the emission spectrum of the phosphorescent film, and the second guest material is a fluorescent molecule with a photoluminescence quantum yield of more than 50%, and the second host material is a film-forming polymer matrix.

[0048] The second main material may be a polymer with good film-forming property, such as polymethyl methacrylate, polyvinyl butyral, polyacrylonitrile, poly(ε-caprolactone), polyethylene-vinyl acetate copolymer, polyacrylic acid, etc.

[0049] The second guest material can be fluorescent molecules such as 9,10-bis(phenylethynyl)anthracene (BPEA), sodium fluorescein (Fluo), 4,7-di(2-thienyl)-2,1,3-benzothiadiazole (DBT), and Nile red (NiR). The second guest material has two characteristics. One is that the absorption spectrum of the second guest material and the emission spectrum of the phosphor film have spectral overlap, and the other is that the second guest material has a higher photoluminescence quantum yield (the photoluminescence quantum yield is above 50%).

[0050] The fluorescent film provided in the embodiment of the present application can be a multicolor fluorescent film with high quantum yield. For example, it can be a fluorescent film obtained by doping 9,10-bisphenylethynyl anthracene (BPEA) as a guest material in PMMA as a host material, or a fluorescent film obtained by doping 4,7-di(2-thienyl)-2,1,3-benzothiadiazole (DBT) as a guest material in PMMA as a host material, or a fluorescent film obtained by doping Nile red (NiR) as a guest material in PMMA as a host material, or a fluorescent film obtained by doping sodium fluorescein (Fluo) as a guest material in PVB as a host material, and so on.

[0051] In the embodiment of the present application, the circularly polarized long afterglow material has an ultra-long afterglow from ultraviolet to near infrared, and the afterglow lifetime is 10 -1 Up to 10 2 For example, the circularly polarized long afterglow material can show blue circularly polarized afterglow, cyan circularly polarized afterglow, green circularly polarized afterglow, yellow circularly polarized afterglow, red circularly polarized afterglow, etc.; and the afterglow life of the circularly polarized long afterglow material can be 6.71s, 6.85s, 6.55s, 6.28s, 6.15s, etc. within 10 -1 Up to 10 2 Lifespan value in the range of s.

[0052] In the embodiment of the present application, the cholesteric liquid crystal polymer film has a selective reflection property for circularly polarized light in the wavelength range from ultraviolet to near infrared, and the circularly polarized light emission asymmetry factor is 10 0For example, in the wavelength range from ultraviolet to near infrared, the measured circularly polarized luminescence asymmetry factor (g lum value) can be 1.50, 1.67, -1.55, -1.51, 1.23, and so on.

[0053] In a second aspect, the present application provides a method for preparing a circularly polarized long afterglow material, comprising the following steps:

[0054] (1) preparing a first film layer, the first film layer comprising at least one of a phosphorescent film and a fluorescent film, wherein the phosphorescent film is prepared by dissolving a first guest material and a first host material in a first solvent, fully mixing them, evaporating the first solvent and drying to obtain the phosphorescent film, and the fluorescent film is prepared by dissolving a second guest material and a second host material in a second solvent, fully mixing them, evaporating the second solvent and drying to obtain the fluorescent film;

[0055] (2) preparing a second film layer, comprising dissolving a liquid crystal monomer, a photoinitiator and a chiral dopant in a third solvent, fully mixing the mixture, and polymerizing the mixture under ultraviolet light to obtain a cholesteric liquid crystal polymer film;

[0056] (3) Assembling the first film layer and the second film layer to obtain a circularly polarized long afterglow material.

[0057] The drying temperature in step (1) can be -100°C to 150°C, and the drying time can be 10 minutes to 10 days.

[0058] It should be noted that the liquid crystal monomer and the photoinitiator used in step (2) may be a liquid crystal mixture, that is, the liquid crystal mixture includes both the liquid crystal monomer and the photoinitiator.

[0059] In the embodiment of the present application, in step (3), the chiral dopant is R-5011 or S-5011, and the amount of the chiral dopant added is 1.9%-2.9% by mass ratio. After a large number of experiments, it was found that by adjusting the addition ratio of the chiral dopant, the photonic bandgap region of the prepared cholesteric liquid crystal polymer film can be adjusted. In the embodiment of the present application, the mass percentage of the chiral dopant can be controlled within the range of 1.9%-2.9%. For example, the mass percentage of the chiral dopant can be 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or any value between any two of the above mass percentages.

[0060] In the embodiment of the present application, the first solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran; the second solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran; the third solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran. Among them, the alcohol solvent may include at least one of methanol, ethanol and propanol.

[0061] It should be understood that the first solvent, the second solvent and the third solvent may be of the same type or different types.

[0062] In the third aspect, the present application provides an application of a circularly polarized long afterglow material in information encryption and anti-counterfeiting materials. Since the circularly polarized long afterglow material provided in the embodiment of the present application has the dual characteristics of time-dependent afterglow and polarization signal, it can have a wide range of application value in information encryption and anti-counterfeiting.

[0063] The sources of the reagents used in the examples of this application are as follows:

[0064] Liquid crystal monomer and photoinitiator are liquid crystal mixtures with the brand name NC-M-LCP1, purchased from Ningcui Optics;

[0065] Chiral dopants (including R-5011 and S-5011), with brand numbers 013393196 and 013550635, respectively, were purchased from Shanghai Titan Technology Co., Ltd.;

[0066] Triphenylene-2-boric acid (TP for short, as shown in formula (I-4)), brand 01235024, purchased from Shanghai Titan Technology Co., Ltd.;

[0067] 9,10-Bisphenylethynylanthracene (BPEA): brand number 1014841-1g, purchased from Shanghai Haohong Biopharmaceutical Technology Co., Ltd.;

[0068] Fluorescein sodium (Fluo): brand number 01082233, purchased from Shanghai Titan Technology Co., Ltd.;

[0069] 4,7-Di(2-thienyl)-2,1,3-benzothiadiazole (DBT): brand number 1135129-100mg, purchased from Shanghai Naicheng Biotechnology Co., Ltd.;

[0070] Nile red (NiR): brand number 7385-67-3, purchased from Shanghai Myrrel Biochemical Technology Co., Ltd.;

[0071] The remaining reagents are conventional commercially available products.

[0072] Example 1

[0073] This embodiment provides a circularly polarized long afterglow material. The preparation method of the circularly polarized long afterglow material comprises the following steps:

[0074] (1) TP (10 mg) was added to a mixed solvent of 1 mL of aqueous ammonia solution (concentration of 25-28 wt%), 1 mL of methanol, and 8 mL of water, and ultrasonicated until it was completely dissolved. As the stock solution of TP, 0.9 mL of the stock solution of TP and 2.8 mL of aqueous polyvinyl alcohol solution (107 mg mL -1 ) and an appropriate amount of water (the amount of water added can be adjusted according to actual conditions) are mixed and ultrasonically treated, the resulting mixture is poured into a culture dish, and heated at 50°C for 2 hours to form a TP-polyvinyl alcohol film (TP-PVA film for short);

[0075] (2) Liquid crystal monomer, photoinitiator and R-5011 (the amount of R-5011 added was 2.87% of the total weight of the three) were dissolved in dichloromethane, volatilized and mixed evenly at room temperature, and the mixture was injected into the liquid crystal box at 80°C and exposed to 365nm ultraviolet light (1.5mW·cm - 2) irradiating for 10 minutes to form a cholesteric liquid crystal polymer film with a blue reflection band (LR-Blue film for short);

[0076] (3) The TP-PVA film and the LR-Blue film are assembled together to form a circularly polarized long afterglow material, namely the TP-LR-Blue film.

[0077] Figure 1 The circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 1 is shown. Figure 2 The lifetime decay curve of the circularly polarized long afterglow material prepared in Example 1 is shown. Figure 1 and Figure 2 As shown, under the excitation of 254nm ultraviolet light, the TP-LR-Blue film has an emission peak at about 475nm, showing a strong blue circularly polarized afterglow, and the afterglow lifetime is tested to be 6.71s.

[0078] Example 2

[0079] This embodiment provides a circularly polarized long afterglow material. The preparation method of the circularly polarized long afterglow material comprises the following steps:

[0080] (1) TP (10 mg) was added to a mixed solvent of 1 mL of ammonia solution (concentration of 25-28 wt%), 1 mL of methanol, and 8 mL of water, and ultrasonicated until it was completely dissolved. 0.9 mL of TP stock solution and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and an appropriate amount of water and subjected to ultrasonic treatment, the resulting mixture was poured into a culture dish and heated at 50°C for 2 hours to form a TP-polyvinyl alcohol film (TP-PVA film for short);

[0081] (2) 1.0 mg of 9,10-bis(phenylethynyl)anthracene and 600 mg of poly(methyl methacrylate) were completely dissolved in dichloromethane and poured onto the preformed TP-PVA film. After evaporating the solvent at room temperature and drying in a vacuum oven, a double-layer TP-BPEA film was obtained;

[0082] (3) Liquid crystal monomer, photoinitiator and R-5011 (the amount of R-5011 added was 2.65% of the total weight of the three) were dissolved in dichloromethane, volatilized and mixed evenly at room temperature, and the mixture was injected into the liquid crystal box at 80°C and exposed to 365nm ultraviolet light (1.5mW·cm - 2) irradiating for 10 minutes to form a cholesteric liquid crystal polymer film with a cyan reflection band (LR-Cyan film for short);

[0083] (4) The TP-BPEA film and the LR-Cyan film are assembled together to form a circularly polarized long afterglow material, namely the TP-BPEA-LR-Cyan film.

[0084] Figure 3 The circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 2 is shown. Figure 4 The lifetime decay curve of the circularly polarized long afterglow material prepared in Example 2 is shown. Figure 3 and Figure 4 As shown, under the excitation of 254nm ultraviolet light, the TP-BPEA-LR-Cyan film has an emission peak at around 500nm, showing a strong cyan circularly polarized afterglow. The afterglow lifetime is tested to be 6.85s.

[0085] Example 3

[0086] This embodiment provides a circularly polarized long afterglow material. The preparation method of the circularly polarized long afterglow material comprises the following steps:

[0087] (1) TP (10 mg) was added to a mixed solvent of 1 mL of ammonia solution (concentration of 25-28 wt%), 1 mL of methanol, and 8 mL of water, and ultrasonicated until it was completely dissolved. 0.9 mL of TP stock solution and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and an appropriate amount of water and subjected to ultrasonic treatment, the resulting mixture was poured into a culture dish and heated at 50°C for 2 hours to form a TP-polyvinyl alcohol film (TP-PVA film for short);

[0088] (2) 1.0 mg of sodium fluorescein and 600 mg of polyvinyl butyral were completely dissolved in ethanol and poured onto the preformed TP-PVA film. After the solvent was evaporated at room temperature and dried in a vacuum oven, a double-layer TP-Fluo film was obtained;

[0089] (3) Liquid crystal monomer, photoinitiator and S-5011 (the amount of S-5011 added was 2.34% of the total weight of the three) were dissolved in dichloromethane, volatilized and mixed evenly at room temperature, and the mixture was injected into the liquid crystal box at 80°C and exposed to 365nm ultraviolet light (1.5mW·cm - 2) irradiating for 10 minutes to form a cholesteric liquid crystal polymer film with a green reflection band (LS-Green film for short);

[0090] (4) The TP-Fluo film and the LR-Green film are assembled together to form a circularly polarized long afterglow material, namely the TP-Fluo-LS-Green film.

[0091] Figure 5 The circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 3 is shown. Figure 6 The lifetime decay curve of the circularly polarized long afterglow material prepared in Example 3 is shown. Figure 5 and Figure 6 As shown, under the excitation of 254nm ultraviolet light, the TP-Fluo-LS-Green film has an emission peak at about 520nm, showing a strong green circularly polarized afterglow. The afterglow lifetime is tested to be 6.55s.

[0092] Example 4

[0093] This embodiment provides a circularly polarized long afterglow material. The preparation method of the circularly polarized long afterglow material comprises the following steps:

[0094] (1) TP (10 mg) was added to a mixed solvent of 1 mL of ammonia solution (concentration of 25-28 wt%), 1 mL of methanol, and 8 mL of water, and ultrasonicated until it was completely dissolved. 0.9 mL of TP stock solution and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and an appropriate amount of water and subjected to ultrasonic treatment, the resulting mixture was poured into a culture dish and heated at 50°C for 2 hours to form a TP-polyvinyl alcohol film (TP-PVA film for short);

[0095] (2) 1.0 mg of 4,7-di(2-thienyl)-2,1,3-benzothiadiazole and 600 mg of polymethyl methacrylate were completely dissolved in dichloromethane and poured onto the preformed TP-PVA film. After the solvent was evaporated at room temperature and dried in a vacuum drying oven, a double-layer TP-DBT film was obtained;

[0096] (3) Liquid crystal monomer, photoinitiator and S-5011 (the amount of S-5011 added was 2.16% of the total weight of the three) were dissolved in dichloromethane, volatilized and mixed evenly at room temperature, and the mixture was injected into the liquid crystal box at 80°C and exposed to 365nm ultraviolet light (1.5mW·cm - 2) irradiating for 10 minutes to form a cholesteric liquid crystal polymer film with a yellow reflection band (LS-Yellow film for short);

[0097] (4) The TP-DBT film and the LS-Yellow film are assembled together to form a circularly polarized long afterglow material, namely the TP-DBT-LS-Yellow film.

[0098] Figure 7 The circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 4 is shown. Figure 8 The lifetime decay curve of the circularly polarized long afterglow material prepared in Example 4 is shown. Figure 7 and Figure 8 As shown, under the excitation of 254nm ultraviolet light, the TP-DBT-LS-Yellow film has an emission peak at about 560nm, showing a strong yellow circularly polarized afterglow. The afterglow lifetime is tested to be 6.28s.

[0099] Example 5

[0100] This embodiment provides a circularly polarized long afterglow material. The preparation method of the circularly polarized long afterglow material comprises the following steps:

[0101] (1) TP (10 mg) was added to a mixed solvent of 1 mL of ammonia solution (concentration of 25-28 wt%), 1 mL of methanol, and 8 mL of water, and ultrasonicated until it was completely dissolved. 0.9 mL of TP stock solution and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and an appropriate amount of water and subjected to ultrasonic treatment, the resulting mixture was poured into a culture dish and heated at 50°C for 2 hours to form a TP-polyvinyl alcohol film (TP-PVA film for short);

[0102] (2) 1.0 mg of Nile red and 600 mg of polymethyl methacrylate were completely dissolved in dichloromethane and poured onto the preformed TP-PVA film. After the solvent was evaporated at room temperature and dried in a vacuum oven, a double-layer TP-NiR film was obtained;

[0103] (3) Liquid crystal monomer, photoinitiator and R-5011 (the amount of R-5011 added was 2.09% of the total weight of the three) were dissolved in dichloromethane, volatilized and mixed evenly at room temperature, and the mixture was injected into the liquid crystal box at 80°C and exposed to 365nm ultraviolet light (1.5mW·cm - 2) irradiating for 10 minutes to form a cholesteric liquid crystal polymer film with a red reflection band (LR-Red film for short);

[0104] (4) The TP-NiR film and the LR-Red film are assembled together to form a circularly polarized long afterglow material, namely the TP-NiR-LR-Red film.

[0105] Fig. 9 The circularly polarized emission spectrum of the circularly polarized long afterglow material prepared in Example 5 is shown. Fig.10 The lifetime decay curve of the circularly polarized long afterglow material prepared in Example 5 is shown. Fig. 9 and Fig.10 As shown, under the excitation of 254nm ultraviolet light, the TP-NiR-LR-Red film has an emission peak at around 620nm, showing a strong red circularly polarized afterglow. The afterglow lifetime is tested to be 6.15s.

[0106] Example 6

[0107] This embodiment provides a method for preparing a multi-dimensional information encryption and anti-counterfeiting material, comprising the following steps:

[0108] (1) Dissolve 1.0 mg NiR and 600 mg PMMA in 10 mL dichloromethane, transfer the solution to a petri dish, and evaporate at room temperature to obtain a transparent and uniform fluorescent NiR-PMMA film;

[0109] (2) Take 0.9 mL of TP stock solution, 0.045 mg of NiR, and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and water and ultrasonically treated, the resulting mixture was poured into a petri dish, heated at 50°C for 2 hours, the membrane was torn off and dried in a vacuum oven to obtain a TP@NiR membrane;

[0110] (3) 10 mg of TP was added to a mixed solvent of 1 mL of ammonia solution (concentration of 25-28 wt%), 1 mL of methanol, and 8 mL of water, and ultrasonicated until it was completely dissolved. This was used as the stock solution of TP. 0.9 mL of the stock solution of TP and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and an appropriate amount of water and ultrasonically treated, the resulting mixture was poured into a petri dish and heated at 50°C for 2 hours to form a TP-PVA film; then, 1.0 mg NiR and 600 mg PMMA were completely dissolved in dichloromethane and poured onto the preformed TP-PVA film, and after evaporating the solvent at room temperature and drying in a vacuum oven, a double-layer TP-NiR film was obtained;

[0111] (4) Using the preparation method provided in Example 5, prepare TP-NiR-LR-Red film;

[0112] (5) 0.9 mL of TP stock solution and 2.8 mL of PVA aqueous solution (107 mg mL -1 ) and an appropriate amount of water and ultrasonically treated, the resulting mixture was poured into a culture dish and heated at 50°C for 2 hours to form a TP-PVA film; then, 1.0 mg NiR and 600 mg PMMA were completely dissolved in dichloromethane and poured onto the pre-formed TP-PVA film, and the solvent was evaporated at room temperature and dried in a vacuum oven to obtain a double-layer TP-NiR film; liquid crystal monomer, photoinitiator and S-5011 (the amount of S-5011 added was 2.09% of the total mass of the three) were dissolved in dichloromethane, volatilized and mixed evenly at room temperature, and the mixture was injected into a liquid crystal box at 80°C and irradiated under 365 nm ultraviolet light (1.5 mW·cm - 2) irradiating for 10 minutes to form a cholesteric liquid crystal polymer film with a red reflection band (LS-Red film for short) by photoinitiated polymerization; assembling the TP-NiR film and the LR-Red film together to form a TP-NiR-LS-Red film;

[0113] (6) Fig.11As shown, NiR-PMMA film, TP@NiR film, TP-NiR film, TP-NiR film, TP-NiR-LR-Red film and TP-NiR-LS-Red film are used to encode hidden information with multi-level encryption. Specifically, under 254nm UV light, the initial code "8888" is exposed; after the UV light is turned off, the second code "8028" appears; further inspection using left-handed or right-handed circular polarizer (L / R-CPF) results in preliminary codes "8726" and "802H", which are not yet the real codes; after the UV light is turned off for 10 seconds, an additional hidden code "2029" is revealed; subsequently, the correct code "2024" is displayed by observation through R-CPF; on the contrary, the use of L-CPF produces an incorrect code "2725". Therefore, the only correct information "2024" can only be seen by observation with R-CPF after the UV light is turned off for 10 seconds.

[0114] The above experimental results show that deviations in time or polarization can lead to the retrieval of incorrect passwords. The circularly polarized long afterglow material with a two-layer or more film structure provided in the embodiments of the present application has great application potential in anti-counterfeiting and encryption.

[0115] Example 7

[0116] This example examines the wavelength and direction of circularly polarized light of the circularly polarized long afterglow material in different assembly sequences by adjusting the assembly sequence of the films. Fig.12 The distance between different film layers and the excitation source is shown in order from near to far. Fig.12 As shown, three different systems are set up based on the order of distance from the excitation source from near to far: (I) TP-PVA, NiR-PMMA, LR-Red; (II) TP-PVA, LR-Blue, NiR-PMMA; (III) LR-Red, TP-PVA, NiR-PMMA.

[0117] Fig.13 The circularly polarized emission spectrum of the circularly polarized long afterglow material of system (I) is shown; Fig.14 The circularly polarized emission spectrum of the circularly polarized long afterglow material of system (II) is shown; Fig.15 The circularly polarized emission spectrum of the circularly polarized long afterglow material of system (III) is shown. Figure 13-15As shown, system (I) produces a strong red CPL positive signal, system (II) produces a blue CPL positive signal, and system (III) produces a red CPL negative signal. For systems (I) and (III), the inversion of the red CPL signal can be achieved by simply changing the relative position of LR-Red in the three-layer film. For system (II), LR-Blue is used to replace LR-Red and inserted between TP-PVA and NiR-PMMA to obtain a blue CPL signal, which means that the CPL wavelength can be regulated.

[0118] The circularly polarized long afterglow material, its preparation method and application provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A circularly polarized long afterglow material, characterized in that: include: A first film layer and a second film layer, wherein the first film layer is a phosphorescent film, or the first film layer includes a phosphorescent film and a fluorescent film, and the second film layer is a cholesteric liquid crystal polymer film.

2. The circularly polarized long afterglow material according to claim 1, characterized in that: The phosphorescent film includes a first guest material and a first host material, wherein the first guest material is an organic aromatic molecule, and the first host material is a rigid polymer matrix material.

3. The circularly polarized long afterglow material according to claim 2, characterized in that: The fluorescent film includes a second guest material and a second host material, the absorption spectrum of the second guest material has spectral overlap with the emission spectrum of the phosphorescent film, and the second guest material is a fluorescent molecule with a photoluminescence quantum yield of more than 50%, and the second host material is a film-forming polymer matrix.

4. The circularly polarized long afterglow material according to claim 3, characterized in that: The first host material includes at least one of polyvinyl alcohol, polyacrylamide, polymethyl methacrylate, polyvinyl butyral resin and polyacrylonitrile; the second host material can be at least one of polymethyl methacrylate, polyvinyl butyral, polyacrylonitrile, poly(ε-caprolactone), polyethylene-vinyl acetate copolymer, and polyacrylic acid; the second guest material includes at least one of 9,10-bis(phenylethynyl)anthracene, sodium fluorescein, 4,7-di(2-thienyl)-2,1,3-benzothiadiazole and Nile red.

5. The circularly polarized long afterglow material according to claim 1, characterized in that: The circularly polarized long afterglow material has an ultra-long afterglow from ultraviolet to near infrared, and the afterglow lifetime is 10 -1 Up to 10 2 s range, the circularly polarized luminescence asymmetry factor is 10 0 Order of magnitude.

6. The circularly polarized long afterglow material according to claim 1, characterized in that: The cholesteric liquid crystal polymer film has a selective reflection characteristic for circularly polarized light in a wavelength range from ultraviolet to near infrared.

7. A method for preparing a circularly polarized long afterglow material, characterized in that: The following steps are involved: (1) preparing a first film layer, wherein the first film layer is a phosphorescent film, or the first film layer includes a phosphorescent film and a fluorescent film, wherein the phosphorescent film is prepared by dissolving a first guest material and a first host material in a first solvent, fully mixing them, evaporating the first solvent and drying to obtain the phosphorescent film, and the fluorescent film is prepared by dissolving a second guest material and a second host material in a second solvent, fully mixing them, evaporating the second solvent and drying to obtain the fluorescent film; (2) preparing a second film layer, comprising dissolving a liquid crystal monomer, a photoinitiator and a chiral dopant in a third solvent, fully mixing the mixture, and polymerizing the mixture under ultraviolet light to obtain a cholesteric liquid crystal polymer film; (3) Assembling the first film layer and the second film layer to obtain the circularly polarized long afterglow material.

8. The method for preparing the circularly polarized long afterglow material according to claim 7, characterized in that: In step (3), the chiral dopant is R-5011 or S-5011, and the added amount of the chiral dopant is 1.9%-2.9% by mass ratio.

9. The method for preparing the circularly polarized long afterglow material according to claim 7, characterized in that: The first solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran; the second solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran; the third solvent includes at least one of water, alcohols, dioxane and tetrahydrofuran.

10. Use of the circularly polarized long afterglow material according to any one of claims 1 to 9 in information encryption and anti-counterfeiting materials.

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