A polymer phosphorescent material with high quantum yield and long phosphorescence lifetime and a preparation method thereof

Abstract

The present invention belongs to the field of polymer luminescent materials, and particularly relates to a polymer phosphorescent material with high quantum yield and long phosphorescence lifetime and a preparation method thereof. The polymer molecular backbone contains unconventional chromophores such as polyethers and amide groups or ester groups. By changing the comonomers and excitation wavelengths, full-color fluorescence emission and room-temperature afterglow emission from blue-green to red-yellow can be achieved, and it can be applied in the fields of anti-counterfeiting, flexible electronic devices, biological detection, etc. The polymer phosphorescent material is based on the hybrid copolymerization of glycidol and acrylamide-based or acrylate-based monomers. A modified branched polyether is prepared by a one-step method, and then heat-treated with boric acid to obtain an amorphous phosphorescent copolymer thin film material. The polymer phosphorescent material prepared by the present invention has rich tunability of emission, high quantum yield, long phosphorescence lifetime, and has the advantages of simple and efficient preparation method, low price, environmental friendliness, etc., is suitable for large-scale production applications, and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of polymer luminescent materials, and particularly relates to a polymer phosphorescent material with high quantum yield and long phosphorescence lifetime and a preparation method thereof. Background Art

[0002] Room temperature phosphorescence (RTP) materials have attracted people's attention due to their unique production process and long-lived excited states. Different from fluorescent materials, RTP materials can directly observe ultra-long afterglow emission from several seconds to dozens of seconds. Among them, organic polymer phosphorescent materials have always been a hot topic. On the one hand, polymer materials play an irreplaceable role in the field of organic flexible electronics, such as organic light-emitting diodes, solar cells, storage devices, field-effect transistors, etc., which mainly benefits from their good flexibility, easy processing, low cost, and high electron mobility. On the other hand, both inorganic and organometallic complex phosphorescent materials have the disadvantages of high cost, high toxicity, and difficult preparation, while organic polymer phosphorescent materials are relatively environmentally friendly and easy to modify.

[0003] Traditional polymer phosphorescent materials carry a large number of conjugated systems, making them have a sufficient rigid structure, but they have inherent disadvantages such as cumbersome preparation steps, poor biocompatibility, and high toxicity, which to a certain extent limit their applications. In recent years, researchers have found that a class of polymers containing unconventional chromophores also exhibit significant photoluminescence properties in the aggregated state. This type of non-traditional polymer luminescent material does not contain traditional conjugated polycyclic chromophores, and only contains unconventional chromophores rich in electron-rich heteroatoms (such as ester groups, amide groups, cyano groups, etc.) to achieve significant luminescence properties through through-space conjugation (TSC). Compared with traditional polymer phosphorescent materials, this type of non-traditional luminescent material also has the advantages of easy preparation, stable structure, good hydrophilicity, and biocompatibility, and has become an ideal candidate material for flexible electronic devices, biological, and medical applications. However, due to the difficulty in overcoming the spin-forbidden nature of singlet-triplet transitions and suppressing non-radiative processes in the amorphous state, the lifetime of this material is generally less than 1.0 s, and the quantum yield is lower than 20%. In addition, the afterglow color and lifetime adjustment of current non-traditional polymer phosphorescent materials are still difficult points. Summary of the Invention

[0004] The object of the present invention is to provide a non-traditional polymer phosphorescent material with high quantum yield and long phosphorescence lifetime and a preparation method thereof, aiming at the disadvantages of difficult preparation of existing non-traditional polymer phosphorescent materials and low luminescence properties such as quantum yield and phosphorescence lifetime.

[0005] To achieve the above object, the present invention copolymerizes a monomer containing alcohol hydroxyl and epoxy structures with a vinyl monomer to prepare a modified branched polyether by a one-step method, and then performs heat treatment with boric acid to obtain an amorphous phosphorescent copolymer thin film material. The specific preparation method steps are as follows:

[0006] (1) A monomer containing an alcohol hydroxyl group and an epoxy structure and a vinyl monomer undergo a copolymerization reaction under the action of a catalyst to prepare a modified branched polyether in one step;

[0007] The monomer containing an alcohol hydroxyl group and an epoxy structure is glycidol or 2-(oxiran-2-yl)ethanol;

[0008] Among them, the vinyl monomer can be a (meth)acrylate, a (meth)acrylamide, a propiolate or an allyl monomer, etc.;

[0009] Specifically: acrylamide, N-isopropylmethacrylamide, N-isopropylacrylamide, N-phenylacrylamide, benzyl methacrylate, phenyl acrylate, tert-butyl methacrylate, benzyl methacrylate, etc.

[0010] The molar ratio of glycidol to the vinyl monomer is (1 - 16):1;

[0011] The catalyst is DBU, TBD, t-BuP1, t-BuP2, t-BuP3, t-BuP4, and the molar ratio of the vinyl monomer to the catalyst is (10 - 200):1.

[0012] The copolymerization reaction adopts bulk polymerization or solution polymerization; it proceeds rapidly and efficiently in the range from 0 °C to 100 °C or even a larger range;

[0013] The solvent used in solution polymerization is any one or a mixture of two of tetrahydrofuran, N,N'-dimethylformamide, dioxane, diethylene glycol dimethyl ether or dimethyl sulfoxide. The mass of the solvent used in solution polymerization is 0.1 - 5 times the mass of the monomer.

[0014] (2) The generated modified branched polyether copolymer and boric acid are subjected to heat treatment crosslinking to form an amorphous transparent phosphorescent polymer film.

[0015] Among them, the heat treatment temperature of the copolymer and boric acid can be in the range from 100 °C to 200 °C or even a larger range, and the heat treatment time is 1 - 20 h.

[0016] The mass ratio of the copolymer to boric acid is (5 - 100):1.

[0017] The polymer has the following structure:

[0018]

[0019] Beneficial effects:

[0020] (1) The raw materials of the present invention are inexpensive and have a wide range of uses: inexpensive and non-toxic glycidol, boric acid and common industrial vinyl monomers are used for polymerization.

[0021] (2) The polymerization reaction conditions are mild, the reaction temperature range is 25 - 100 °C, the heat treatment temperature range is 50 - 200 °C, the catalyst used does not contain metal ions, is easy to be removed, and does not affect the properties of the polymer.

[0022] (3) The polymerization process is simple: using a simple compound as the catalyst, the polymer can be prepared by a one-step method, and the polymer phosphorescent film can be made through simple heat treatment without doping into other polymer matrices.

[0023] (4) The prepared polymer phosphorescent afterglow has rich and adjustable colors. Moreover, it is an amorphous polymer itself, has good film-forming properties, does not require doping, and has good application prospects. Description of the Drawings

[0024] Figure 1 It is the phosphorescent afterglow diagrams of various polymers.

[0025] Figure 2 It is the photo of the polymer film under sunlight.

[0026] Figure 3 It is the schematic diagram of the reaction process of the present invention.

[0027] Figure 4 a is the fluorescence excitation-emission two-dimensional spectrum of the unmodified branched polyether, b is the fluorescence excitation-emission two-dimensional spectrum of the phosphorescent polymer, and c is the phosphorescence excitation-emission two-dimensional spectrum of the phosphorescent polymer in Example 1.

[0028] Figure 5 It is the phosphorescence lifetime diagrams of the polymers in Example 1 and Example 7. Detailed Embodiments

[0029] The following further illustrates the present invention with examples, but is not limited to the following examples. For the process parameters not specifically noted, conventional techniques can be referred to.

[0030] Example 1

[0031] Place a dry 5 mL round-bottom flask with a rotor into a glove box filled with an argon atmosphere. Add 0.480 g (6.75 mmol) of acrylamide, 0.5 g (6.75 mmol) of glycidol, and 42.2 μL (0.03 mmol) of t-BuP4 into it. Cover it with a rubber stopper and take it out, then place it in an oil bath at 25 °C and react for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate it in 100 mL of n-hexane to obtain a pale yellow product, dry it under vacuum at 30 °C for 1 h. Add 0.196 g of boric acid into it and perform heat treatment in an oven at 100 °C for 3 h. The obtained product is a pale yellow transparent film, which can emit blue-white fluorescence when excited at a wavelength of 365 nm, and shows blue-green afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 23.2%, the phosphorescence quantum yield is 8.1%, and the phosphorescence lifetime is 2746 ms.

[0032] Example 2

[0033] Place a dry 5 mL round-bottom flask with a rotor into a glove box filled with an argon atmosphere. Add 0.053 g (0.42 mmol) of N-isopropylmethacrylamide, 0.5 g (6.75 mmol) of glycidol, and 0.042 g (0.30 mmol) of DBU into it. Cover it with a rubber stopper and take it out, then place it in an oil bath at 50 °C and react for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate it in 100 mL of n-hexane to obtain a pale yellow product, dry it under vacuum at 30 °C for 1 h. Add 0.110 g of boric acid into it and perform heat treatment in an oven at 200 °C for 20 h. The obtained product is a yellow transparent film, which can emit white fluorescence when excited at a wavelength of 365 nm, and shows green afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 26.1%, the phosphorescence quantum yield is 7.6%, and the phosphorescence lifetime is 1574 ms.

[0034] Example 3

[0035] Place a dry 5 mL round-bottom flask with a rotor into a glove box filled with an argon atmosphere. Add 0.147 g (1.30 mmol) of N-isopropylacrylamide, 0.5 g (6.75 mmol) of glycidol, and 60.4 μL (0.12 mmol) of t-BuP2 into it. Cover it with a rubber stopper and take it out, then place it in an oil bath at 25 °C and react for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate it in 100 mL of n-hexane to obtain a pale yellow product, dry it under vacuum at 30 °C for 1 h. Add 0.065 g of boric acid into it and perform heat treatment in an oven at 150 °C for 3 h. The obtained product is a yellow transparent film, which can emit blue fluorescence when excited at a wavelength of 365 nm, and shows blue-green afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 21.3%, the phosphorescence quantum yield is 5.3%, and the phosphorescence lifetime is 2608 ms.

[0036] Example 4

[0037] A dry 5 mL round-bottom flask equipped with a rotor was placed in a glove box filled with an argon atmosphere. 0.497 g (3.38 mmol) of N-phenylacrylamide, 0.5 g (6.75 mmol) of glycidyl and 170 μL (0.68 mmol) of t-BuP1 were added thereto. After covering with a rubber stopper, it was taken out and placed in an oil bath at 100 °C for 6 h. After the reaction was completed, the reaction product was dissolved in tetrahydrofuran and precipitated in 100 mL of n-hexane to obtain a pale yellow product, which was dried in vacuo at 30 °C for 1 h. 0.010 g of boric acid was added thereto and heat-treated in an oven at 120 °C for 3 h. The resulting product was a yellow transparent film, which could emit white fluorescence when excited at a wavelength of 365 nm and showed a yellow-green afterglow for several seconds after the excitation light source was turned off. The absolute quantum yield was 19.8%, the phosphorescence quantum yield was 2.2%, and the phosphorescence lifetime was 1210 ms.

[0038] Example 5

[0039] A dry 5 mL round-bottom flask equipped with a rotor was placed in a glove box filled with an argon atmosphere. 0.299 g (4.20 mmol) of acrylamide, 0.5 g (6.75 mmol) of glycidyl and 0.095 g (0.68 mmol) of TBD were added thereto. After covering with a rubber stopper, it was taken out and placed in an oil bath at 60 °C for 6 h. After the reaction was completed, the reaction product was dissolved in tetrahydrofuran and precipitated in 100 mL of n-hexane to obtain a pale yellow product, which was dried in vacuo at 30 °C for 1 h. 0.020 g of boric acid was added thereto and heat-treated in an oven at 180 °C for 3 h. The resulting product was a yellow transparent film, which could emit blue-white fluorescence when excited at a wavelength of 365 nm and showed a green afterglow for several seconds after the excitation light source was turned off. The absolute quantum yield was 27.9%, the phosphorescence quantum yield was 7.9%, and the phosphorescence lifetime was 1703 ms.

[0040] Example 6

[0041] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 1.189 g (6.75 mmol) of benzyl methacrylate, 0.5 g (6.75 mmol) of glycidol, 0.095 g (0.68 mmol) of DBU, and 0.17 g of dimethyl sulfoxide thereto. Cover with a rubber stopper, take it out, and place it in an oil bath at 25 °C for 6 h. After the reaction is completed, dissolve the reaction product in tetrahydrofuran and precipitate it in 100 mL of n-hexane to obtain a pale yellow product. Dry it under vacuum at 30 °C for 1 h. Add 0.052 g of boric acid thereto and perform heat treatment in an oven at 100 °C for 1 h. The resulting product is a yellow transparent film, which can emit blue fluorescence when excited at a wavelength of 365 nm and exhibit yellow afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 19.9%, the phosphorescence quantum yield is 5.1%, and the phosphorescence lifetime is 1106 ms.

[0042] Example 7

[0043] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.741 g (5.00 mmol) of phenyl acrylate, 0.5 g (6.75 mmol) of glycidol, and 120.8 μL (0.24 mmol) of t-BuP2, and 6.2 g of tetrahydrofuran thereto. Cover with a rubber stopper, take it out, and place it in an oil bath at 25 °C for 6 h. After the reaction is completed, dissolve the reaction product in tetrahydrofuran and precipitate it in 100 mL of n-hexane to obtain a pale yellow product. Dry it under vacuum at 30 °C for 1 h. Add 0.120 g of boric acid thereto and perform heat treatment in an oven at 200 °C for 1 h. The resulting product is a yellow transparent film, which can emit white fluorescence when excited at a wavelength of 365 nm and exhibit yellow afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 14.8%, the phosphorescence quantum yield is 3.4%, and the phosphorescence lifetime is 689 ms.

[0044] Example 8

[0045] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.442 g (3.00 mmol) of N-phenylacrylamide, 0.5 g (2.43 mmol) of glycidol, and 85 μL (0.34 mmol) of t-BuP1, and 2 g of N,N'-dimethylformamide. Cover with a rubber stopper, take it out, and place it in an oil bath at 25 °C for 6 h. After the reaction, dissolve the reaction product in tetrahydrofuran and precipitate it in 100 mL of n-hexane to obtain a pale yellow product. Dry it under vacuum at 30 °C for 1 h. Add 0.020 g of boric acid to it and perform heat treatment in an oven at 120 °C for 10 h. The resulting product is a yellow transparent film, which can emit blue-white fluorescence when excited at a wavelength of 365 nm and show yellow-green afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 14.1%, the phosphorescence quantum yield is 3.9%, and the phosphorescence lifetime is 892 ms.

[0046] Example 9

[0047] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.529 g (3.00 mmol) of benzyl methacrylate, 0.5 g (6.75 mmol) of glycidol, and 0.028 g (0.20 mmol) of DBU, and 2 g of dioxane. Cover with a rubber stopper, take it out, and place it in an oil bath at 25 °C for 6 h. After the reaction, dissolve the reaction product in tetrahydrofuran and precipitate it in 100 mL of n-hexane to obtain a pale yellow product. Dry it under vacuum at 30 °C for 1 h. Add 0.050 g of boric acid to it and perform heat treatment in an oven at 110 °C for 15 h. The resulting product is a yellow transparent film, which can emit blue-white fluorescence when excited at a wavelength of 365 nm and show yellow-green afterglow for several seconds after turning off the excitation light source. The absolute quantum yield is 12.9%, the phosphorescence quantum yield is 1.7%, and the phosphorescence lifetime is 1382 ms.

[0048] Example 10

[0049] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.339 g (3.00 mmol) of N-isopropylacrylamide, 0.5 g (6.75 mmol) of glycidol, and 0.042 g (0.30 mmol) of TBD, and 1.5 g of diethylene glycol dimethyl ether thereto. Cover with a rubber stopper and take out, and place it in an oil bath at 25 °C for reaction for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate in 100 mL of n-hexane to obtain a pale yellow product, vacuum dry at 30 °C for 1 h, add 0.020 g of boric acid thereto, and perform heat treatment in an oven at 200 °C for 6 h. The obtained product is a yellow transparent film, which can emit blue-white fluorescence under excitation at a wavelength of 365 nm, and a blue-green afterglow appears for several seconds after turning off the excitation light source. The absolute quantum yield is 17.6%, the phosphorescence quantum yield is 5.2%, and the phosphorescence lifetime is 1420 ms.

[0050] Example 11

[0051] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.339 g (3.00 mmol) of N-isopropylacrylamide, 0.595 g (6.75 mmol) of 2-(oxiran-2-yl)ethanol, and 0.042 g (0.30 mmol) of TBD, and 1.5 g of diethylene glycol dimethyl ether thereto. Cover with a rubber stopper and take out, and place it in an oil bath at 25 °C for reaction for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate in 100 mL of n-hexane to obtain a pale yellow product, vacuum dry at 30 °C for 1 h, add 0.020 g of boric acid thereto, and perform heat treatment in an oven at 200 °C for 6 h. The obtained product is a yellow transparent film, which can emit blue-white fluorescence under excitation at a wavelength of 365 nm, and a green afterglow appears for several seconds after turning off the excitation light source. The absolute quantum yield is 10.2%, the phosphorescence quantum yield is 3.2%, and the phosphorescence lifetime is 651 ms.

[0052] Example 12

[0053] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.680 g (6.00 mmol) of N-isopropylacrylamide, 0.5 g (2.43 mmol) of glycidol, 0.042 g (0.30 mmol) of TBD, and 1.5 g of diethylene glycol dimethyl ether thereto. Cover with a rubber stopper and take out, place in an oil bath at 25 °C, and react for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate in 100 mL of n-hexane to obtain a pale yellow product, dry it under vacuum at 30 °C for 1 h, add 0.020 g of boric acid thereto, and perform heat treatment in an oven at 200 °C. The obtained product is a yellow transparent film, which can emit blue-white fluorescence when excited at a wavelength of 365 nm, and a green afterglow appears for several seconds after turning off the excitation light source. The absolute quantum yield is 14.2%, the phosphorescence quantum yield is 5.6%, and the phosphorescence lifetime is 1051 ms.

[0054] Example 13

[0055] Place a dry 5 mL round-bottom flask equipped with a rotor into a glove box filled with an argon atmosphere. Add 0.442 g (3.00 mmol) of N-phenylacrylamide, 0.5 g (2.43 mmol) of glycidol, and 85 μL (0.34 mmol) of t-BuP1, and 2 g of N,N'-dimethylformamide thereto. Cover with a rubber stopper and take out, place in an oil bath at 25 °C, and react for 6 h. After the reaction is completed, dissolve the reaction product with tetrahydrofuran, precipitate in 100 mL of n-hexane to obtain a pale yellow product, dry it under vacuum at 30 °C for 1 h, add 0.020 g of boric acid thereto, and perform heat treatment in an oven at 170 °C. The obtained product is a yellow transparent film, which can emit blue-white fluorescence when excited at a wavelength of 365 nm, and a yellow-green afterglow appears for several seconds after turning off the excitation light source. The absolute quantum yield is 17.6%, the phosphorescence quantum yield is 5.9%, and the phosphorescence lifetime is 937 ms.

Claims

1. A preparation method of a polymer phosphorescent material with high quantum yield and long phosphorescence lifetime, characterized in that, The preparation method comprises the following steps: (1) A monomer containing an alcohol hydroxyl group and an epoxy structure and a vinyl monomer are subjected to a copolymerization reaction under the action of a catalyst to prepare a modified branched polyether; The monomer containing an alcohol hydroxyl group and an epoxy structure is glycidyl or 2-(oxiran-2-yl)ethanol; the vinyl monomer is a (meth)acrylate or (meth)acrylamide monomer; (2) The produced modified branched polyether copolymer and boric acid are subjected to heat treatment crosslinking to form an amorphous transparent phosphorescent polymer film.

2. The preparation method of the polymer phosphorescent material with high quantum yield and long phosphorescence lifetime according to claim 1, characterized in that, The molar ratio of the monomer containing an alcohol hydroxyl group and an epoxy structure to the vinyl monomer is 1-16:1, and the copolymerization reaction temperature is ≥0 °C.

3. The preparation method of the polymer phosphorescent material with high quantum yield and long phosphorescence lifetime according to claim 1, characterized in that, The catalyst is DBU, TBD, t-BuP1, t-BuP2, t-BuP3 or t-BuP4, and the molar ratio of the vinyl monomer to the catalyst is 10-200:

1.

4. The preparation method of the polymer phosphorescent material with high quantum yield and long phosphorescence lifetime according to claim 1, characterized in that, The copolymerization reaction adopts bulk polymerization or solution polymerization.

5. The preparation method of the polymer phosphorescent material with high quantum yield and long phosphorescence lifetime according to claim 4, characterized in that The solvent used in the solution polymerization is any one or a mixture of two of tetrahydrofuran, N,N-dimethylformamide, dioxane, diethylene glycol dimethyl ether or dimethyl sulfoxide, and the mass of the solvent used in the solution polymerization is 0.1-5 times the mass of the monomer.

6. The preparation method of the polymer phosphorescent material with high quantum yield and long phosphorescence lifetime according to claim 1, characterized in that, The heat treatment temperature is ≥100 °C, and the heat treatment time is 1-20 h.

7. The preparation method of the polymer phosphorescent material with high quantum yield and long phosphorescence lifetime according to claim 1, characterized in that, The mass ratio of the copolymer to boric acid is 5-100:

1.

8. A polymer phosphorescent material with high quantum yield and long phosphorescence lifetime prepared by the method according to any one of claims 1-7, characterized in that, The polymer has the following structure:

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