Method for preparing polyacrylamide-based room temperature phosphorescent polymer film through microwave radiation

Abstract

The invention relates to a method for preparing a polyacrylamide-based room-temperature phosphorescent polymer film through microwave radiation, and belongs to the field of organic light-emitting materials. The method comprises the following steps: dissolving an acrylamide monomer, an ammonium persulfate initiator and a beta-diketone ligand in a mixed solvent of water and acetonitrile, placing in a microwave reactor, polymerizing under microwave radiation to obtain a polymer, uniformly coating a polyfluortetraethylene plate or a silica gel plate with a colloidal solution dissolved by deionized water, and drying to obtain the beta-diketone / acrylamide composite material. And drying to obtain the polyacrylamide-based room-temperature phosphorescent polymer film. The prepared polymer film shows blue or blue-green fluorescence and green afterglow, and the afterglow time of the polymer film containing 4, 4, 4-trifluoro-1-(2-naphthyl)-1, 3-butanedione is as long as 7.5 seconds. The raw materials are easy to obtain, the preparation method is simple, convenient and rapid, inert gas protection is not needed, the used solvent does not need to be treated, polymerization can be completed within a few minutes, and the obtained material is non-toxic, pollution-free, heavy metal-free, halogen-free, good in water solubility and wide in application prospect.

Description

Technical Field

[0001] The invention relates to a microwave radiation method for preparing a room temperature phosphorescent polymer film based on polyacrylamide, and belongs to the field of organic luminescent materials. Background Art

[0002] The amide groups in the polyacrylamide structure are easy to form intermolecular and intramolecular hydrogen bonds, which can effectively restrict the movement of the molecular chain and inhibit non-radiative transitions. At the same time, nitrogen atoms and oxygen atoms are conducive to n-π * Transition and spin-orbit coupling can achieve efficient room temperature phosphorescence. Due to the sensitivity of room temperature phosphorescent materials to temperature, oxygen, and humidity, the realization of room temperature phosphorescence requires strict control of oxygen and humidity. In order to suppress the quenching effect of oxygen and humidity on room temperature phosphorescent materials, the preparation of room temperature phosphorescent polymer films based on polyacrylamide is mostly achieved by solution polymerization using traditional heating methods under the conditions of dehydrated organic solvents and inert gases. Due to its long reaction cycle, strict requirements on organic solvents, synthesis conditions and atmosphere, it increases the difficulty of synthesis, reduces the reaction rate, and reduces the yield; at the same time, the generation of linear polymers during the polymerization process can increase the viscosity of the reaction system or generate a network structure polymer to prevent the continued polymerization of the monomer, resulting in a decrease in conversion rate and affecting the continued increase in the degree of polymerization of the polymer.

[0003] Compared with infrared, far infrared and other electromagnetic waves that heat by radiation, microwaves have the characteristics of penetrating, selective heating and non-ionizing, which rapidly catalyze the application of microwave technology in the field of organic synthesis. Microwaves are a special type of high-frequency energy. In polar solvent systems, microwave energy has strong penetrating power. While accelerating the violent movement of solvent and solute molecules, it can also play a deep heating role on the molecules in the system, that is, the "thermal effect", so that the reaction can be completed in a short time. In solution polymerization reactions, the use of microwave methods can complete polymerization in a short time and obtain polymers with larger molecular weights, which can overcome the defects of traditional heating methods.

[0004] The present invention uses a microwave radiation method to quickly prepare a room temperature phosphorescent polymer film based on polyacrylamide, and the solvent does not need to be dehydrated, and polymerization can be completed in an air atmosphere; the groups (β-diketone, fluorine atoms, etc.) in the β-diketone ligand (4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione or trifluoro-1-(2-furanyl)-1,3-butanedione) in the system interact with the polymer, so that the polymer chain is better aggregated, thereby more effectively restricting the movement of the molecular chain and inhibiting non-radiative transitions, thereby achieving phosphorescent emission. Summary of the invention

[0005] The object of the present invention is to provide a microwave radiation method for preparing a room temperature phosphorescent polymer film based on polyacrylamide.

[0006] The technical solution adopted to achieve the purpose of the present invention is: Add acrylamide monomer, ammonium persulfate initiator and β-diketone ligand into a round-bottom flask, add deionized water and acetonitrile mixed solvent to dissolve, the mass ratio of monomer, initiator, ligand and solvent in the system is 100:0.5~1.2:0.5~1:800~1500, place in a microwave chemical reactor, microwave reflux reaction at a certain microwave power for 3~15 minutes, cool to room temperature, precipitate with methanol, filter, wash the filter cake with methanol, dissolve with deionized water to obtain a colloidal solution, evenly coat it on a polytetrafluoroethylene plate or a silica gel plate, and dry at 40~50°C to obtain a room temperature phosphorescent polymer film based on polyacrylamide.

[0007] The β-diketone ligand is 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione or trifluoro-1-(2-furanyl)-1,3-butanedione.

[0008] The volume ratio of the deionized water and acetonitrile mixed solvent is 10:1-1.5.

[0009] The microwave output power of the microwave reactor is 50W-750W.

[0010] Compared with the prior art, the present invention has the following significant advantages: The polymer film prepared according to the present invention emits blue or blue-green fluorescence under 254nm or 365nm ultraviolet light, has a strong green afterglow and a long afterglow time at room temperature after the ultraviolet light is extinguished, and the polymer phosphorescent material containing 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione has an afterglow time of up to 7.5 seconds. At the same time, the preparation method is simple and convenient, the preparation conditions are mild, the condenser tube is directly connected to the atmosphere during the reaction process, no inert gas protection is required, the solvent and raw materials do not need special treatment, the raw materials are easy to obtain, and the preparation is fast using a microwave chemical reactor, and the polymerization can be completed in a few minutes; the phosphorescent material prepared by the present invention is non-toxic, non-polluting, heavy metal-free, halogen-free, has good water solubility, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The fluorescence excitation and emission spectra of the polyacrylamide-based room temperature phosphorescent polymer film prepared in Example 1.

[0012] Figure 2 This is the delayed emission spectrum of the polyacrylamide-based room temperature phosphorescent polymer film prepared in Example 1.

[0013] Figure 3 These are the fluorescence excitation and emission spectra of the polyacrylamide-based room temperature phosphorescent polymer film prepared in Example 2.

[0014] Figure 4 This is the delayed emission spectrum of the polyacrylamide-based room temperature phosphorescent polymer film prepared in Example 2. DETAILED DESCRIPTION

[0015] The present invention is further described below by means of specific examples, but these specific embodiments do not limit the protection scope of the present invention in any way. Example 1

[0016] 1 g acrylamide, 0.009 g ammonium persulfate and 0.007 g 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione were added to a round-bottom flask, and a mixed solvent of 9 mL deionized water and 1 mL acetonitrile was added to dissolve the mixture. The mixture was placed in a microwave chemical reactor and subjected to microwave reflux reaction at a microwave power of 600 W for 8 min. After cooling to room temperature, the mixture was precipitated with methanol and filtered to obtain a polymer. The polymer was then washed with methanol for multiple times to remove unreacted small molecules, and the colloidal solution obtained by dissolving the polymer with 15 mL deionized water was evenly coated on a polytetrafluoroethylene plate or a silica gel plate, and dried at 40-50° C. to obtain a room temperature phosphorescent polymer film based on polyacrylamide.

[0017] The prepared polymer film exhibits blue light emission under 254nm and 365nm ultraviolet light. Figure 1 The figure is the fluorescence excitation and emission spectrum of the prepared polymer, and blue light emission at 440nm appears under excitation at 267nm and 365nm wavelengths.

[0018] When the light source is turned off after irradiation with 254nm and 365nm ultraviolet lamps, there is a bright green afterglow, and the afterglow time is 7 seconds and 7.5 seconds respectively.

[0019] Figure 2 It is the delayed emission spectrum of the polymer film. The delayed emission wavelength is at 545 nm, which is green light. Example 2

[0020] 1 g acrylamide, 0.01 g ammonium persulfate and 0.0065 g trifluoro-1-(2-furyl)-1,3-butanedione were added to a round-bottom flask, and a mixed solvent of 8 mL deionized water and 2 mL acetonitrile was added to dissolve the mixture. The mixture was placed in a microwave chemical reactor and subjected to microwave reflux reaction at a microwave power of 375 W for 11 min. After cooling to room temperature, the mixture was precipitated with methanol and filtered to obtain a polymer. The polymer was then washed with methanol for multiple times to remove unreacted small molecules. The colloidal solution obtained by dissolving the polymer with 15 mL deionized water was evenly coated on a polytetrafluoroethylene plate or a silica gel plate, and dried at 40-50° C. to obtain a room temperature phosphorescent polymer film based on polyacrylamide.

[0021] The prepared polymer film exhibits blue-green light and blue light under 254nm and 365nm ultraviolet light, respectively. Figure 3 Figure 3 is the fluorescence excitation and emission spectra of the prepared polymer. Under 254 nm excitation, the emission wavelength is 493 nm. Under 365 nm excitation, the emission wavelengths are 436 nm and 493 nm.

[0022] When the light source is turned off after irradiation with 254nm and 365nm ultraviolet lamps, the afterglow time is 2 seconds and 3.5 seconds respectively.

[0023] Figure 4 This is the delayed emission spectrum of the polymer film. In the emission spectrum with a delay time of 1 ms, the emission wavelength at 254 nm is 493 nm, which is a blue-green afterglow, and the emission wavelength at 365 nm is 519 nm, which is a green afterglow.

Claims

1. A microwave radiation method for preparing a room temperature phosphorescent polymer film based on polyacrylamide, characterized in that Add acrylamide monomer, ammonium persulfate initiator and β-diketone ligand into a round-bottom flask, add deionized water and acetonitrile mixed solvent to dissolve, the mass ratio of monomer, initiator, ligand and solvent in the round-bottom flask system is 100:0.5~1.2:0.5~1:800~1500, place in a microwave chemical reactor, microwave reflux reaction at a certain microwave power for 3~15 minutes, cool to room temperature, precipitate with methanol, filter, wash the filter cake with methanol, dissolve with deionized water to obtain a colloidal solution, evenly coat it on a polytetrafluoroethylene plate or a silica gel plate, and dry at 40~50°C to obtain a room temperature phosphorescent polymer film based on polyacrylamide.

2. The method of preparing a room temperature phosphorescent polymer film based on polyacrylamide by microwave radiation according to claim 1, characterized in that The β-diketone ligand is 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione or trifluoro-1-(2-furanyl)-1,3-butanedione.

3. The method of preparing a room temperature phosphorescent polymer film based on polyacrylamide by microwave radiation according to claim 1, characterized in that The volume ratio of the deionized water and acetonitrile mixed solvent is 10:1-1.

5.

4. The method of preparing a room temperature phosphorescent polymer film based on polyacrylamide by microwave radiation according to claim 1, characterized in that The microwave output power of the microwave reactor is 50W-750W.

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