Method for synthesizing colorful luminous polymer film by microwave method

Abstract

The invention relates to a method for synthesizing a colorful luminous polymer film by a microwave method. The method comprises the following steps: dissolving acrylamide, ammonium persulfate and alpha-thiophenoyl trifluoroacetone in a solvent, performing reflux reaction under certain microwave power, cooling to room temperature, and separating out by using methanol to obtain a polymer A; dissolving in deionized water, adding a europium nitrate solution, adjusting the pH to be neutral, oscillating, standing, and separating out a polymer B by using methanol; and finally, dissolving with deionized water to obtain a colloidal solution. Dropwise adding the colloidal solution into a silica gel mold, and drying to obtain the colorful luminous polymer film. The preparation method disclosed by the invention is simple, convenient and rapid, does not need inert gas protection, can finish polymerization within several minutes, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to a method for synthesizing a colorful luminescent polymer film using a microwave method, and belongs to the field of preparation of organic luminescent materials. Background Art

[0002] In recent years, room temperature phosphorescence (RTP) materials have attracted great attention from scientists. Phosphorescent materials can emit light during light excitation and for a certain period of time after the light excitation stops, such as the light emission of night pearls, and can be used as display and lighting materials. At present, phosphorescent materials mainly include inorganic compounds, metal complexes, pure organic compounds, polymers, etc. Among them, organic polymer phosphorescent materials have good flexibility, ductility, processability, plasticity, high electron mobility, low toxicity, good biocompatibility, environmental friendliness, low cost and other advantages, and are suitable for various organic optoelectronic flexible materials. The strategy for constructing organic polymer room temperature phosphorescent materials is mainly through host-guest interactions and hydrogen bonds, molecular assembly, ionic bond interactions, etc. At present, room temperature phosphorescent materials based on polymer matrices have been reported, mainly including polymer matrices such as polylactic acid (PLA), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polyacrylamide (PAM), polyacrylonitrile (PAN), polystyrene sulfonic acid (PSS) and sodium polystyrene sulfonate. The amide groups in the polyacrylamide structure are easy to form intramolecular and intermolecular hydrogen bonds, which can effectively restrict the movement of molecules and polymers and inhibit non-radiative transitions. At the same time, N atoms and O atoms are conducive to n-π * Transition and spin-orbit coupling can achieve efficient room temperature phosphorescence. Therefore, organic room temperature phosphorescent polymers based on polyacrylamide have been deeply explored and studied in recent years.

[0003] 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, traditional organic room temperature phosphorescent materials, including those based on polyacrylamide polymer materials, are mostly synthesized under the conditions of organic solvents and inert gases without water. They are usually prepared by solution free radical polymerization using traditional heating methods. During the polymerization process, linear polymers are generated, which can increase the viscosity of the reaction system or generate network-structured polymers to make the reaction system jelly-like. Then they will prevent the continued polymerization of monomers, resulting in a decrease in conversion rate and affecting the continued increase in the degree of polymerization of the polymer. Microwaves are a special 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 is completed in a short time. In solution polymerization reactions, the use of microwave methods can overcome the defects of traditional heating methods. It can make the solvent and monomer, polymer and other molecules in the system absorb higher microwave energy and move violently, which can significantly accelerate the reaction rate and improve the reaction conversion rate. The polymerization can be completed in a short time and a polymer with a larger molecular weight can be obtained.

[0004] At present, the fluorescence emission of polyacrylamide room temperature phosphorescent materials is basically blue-violet light. In order to enrich the fluorescence emission, the present invention introduces red light rare earth europium. First, a microwave reactor is used to prepare a polyacrylamide polymer containing α-thenoyltrifluoroacetone ligand by free radical polymerization. Then, rare earth europium ions (Eu 3+ ) and the coordination effect of the ligand β-diketone group in the polymer, rare earth europium is introduced into the polymer, and the prepared polymer film material exhibits different luminescent colors under different excitation wavelengths, and is regulated within the range of 260nm~400nm, achieving full-color luminescence from blue light to red light. After turning off the ultraviolet light, color-changing afterglow can be achieved, and the film exhibits a significant stimulus response to temperature changes in light color. The preparation method of the present invention is simple, convenient and rapid, does not require inert gas protection, and can complete polymerization in a few minutes. The prepared polymer material has excellent luminescent properties and has broad application prospects. Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing a colorful luminous polymer film by a microwave method.

[0006] The technical solution adopted to achieve the purpose of the present invention is: A method for synthesizing a colorful luminescent polymer film using a microwave method, characterized in that: 1. After acrylamide, ammonium persulfate and α-thenoyltrifluoroacetone are dissolved in a solvent, the mixture is placed in a microwave chemical reactor, and microwave reflux reaction is performed for a certain period of time at a certain microwave power. After cooling to room temperature, the polymer A is precipitated with methanol, and the polymer A is washed until the washing liquid is clear; The mass ratio of acrylamide, ammonium persulfate, α-thenoyltrifluoroacetone and solvent is 100: (0.5-1.2): (0.5-1.3): (1000-1500); The solvent is a mixed solvent of deionized water and acetonitrile, and the volume ratio of deionized water to acetonitrile is 10:1-1.5; The certain microwave power has an output power of 50W to 750W; The microwave reflux reaction has a reaction time of 3 to 15 minutes.

[0007] 2. Dissolve the washed polymer A with deionized water, add an appropriate amount of europium nitrate solution after dissolution, adjust the pH to neutral with NaOH solution, shake, let stand for a few minutes, and precipitate with methanol to obtain polymer B.

[0008] An appropriate amount of europium nitrate is added, and the molar ratio of europium nitrate to α-thenoyltrifluoroacetone is 1:1-5.

[0009] 3. Dissolve polymer B in deionized water to obtain a colloidal solution, drop the colloidal solution into a circular silica gel mold, place it in a 40° C. oven, and dry it for 24 hours to obtain the colorful luminescent polymer film of the present invention.

[0010] The present invention has the following advantages: 1. The preparation method is simple and convenient, the preparation conditions are mild, the reaction process does not require inert gas protection, and the solvent does not require special treatment.

[0011] 2. The preparation is fast using a microwave chemical reactor, and the polymerization can be completed in a few minutes.

[0012] 3. The polymer film material prepared by the present invention exhibits different luminescent colors under different excitation wavelengths, and can be regulated in the range of 260nm~400nm by changing the excitation wavelength, thereby realizing full-color luminescence of the polymer film from blue light to red light, and color-changing afterglow can be achieved after turning off the ultraviolet light.

[0013] 4. The polymer film material prepared by the present invention exhibits a significant light color change stimulus response to temperature. Placing the film at high temperature can achieve a change in the light color of the film from red to blue, and the light color will change back to red when the temperature returns to room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1The luminescent colors of the polymer film prepared in Example 1 under excitation at 254 nm, 310 nm, 365 nm and 400 nm respectively; Figure 2 is the corresponding emission spectrum.

[0015] Figure 3 The color of the afterglow of the polymer film prepared in Example 1 changes with time after the light source is turned off after being excited at 310 nm.

[0016] Figure 4 These are the spectra at different time delays.

[0017] Figure 5 The luminescent color of the polymer film prepared in Example 1 changes with temperature.

[0018] Figure 6 These are the emission spectra at different temperatures. DETAILED DESCRIPTION

[0019] 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.

[0020] Example 1 In a 50mL round-bottom flask, add 1g acrylamide, 0.01g ammonium persulfate and 0.0065g α-thiophenecarbonyl trifluoroacetone, dissolve with 9mL deionized water and 1mL acetonitrile solvent, place in a microwave chemical reactor, reflux reaction at a microwave power of 600W for 7.5 min, wait for the container to cool to room temperature naturally, precipitate with methanol to obtain polymer A. Then wash polymer A with methanol several times until the washing liquid is clear, take out polymer A and dissolve it with 30mL deionized water, add 0.01mmol europium nitrate solution, adjust pH to neutral with NaOH solution, shake, stand for 10 minutes, precipitate polymer B with methanol, dissolve with deionized water to obtain colloidal solution. Take 1mL of colloidal solution and drop it into a circular silica gel mold with a diameter of 2cm, place it in a 40℃ oven, and dry it for 24h to obtain a colorful luminescent polymer film.

[0021] The prepared polymer film exhibits green, orange, red and blue luminescence under excitation at 254nm, 310nm, 365nm and 400nm wavelengths, respectively ( Figure 1 ), Figure 2 It is the emission spectra of the polymer film under excitation at 254nm, 310nm, 365nm and 400nm.

[0022] After irradiating the polymer film with 310 nm ultraviolet light for a period of time and then turning off the light source, the film emits an afterglow, the color of which changes over time, showing a color-changing afterglow from yellow to cyan and then to green ( Figure 3 ). The different time delay spectra of the polymer are shown in Figure 4 .

[0023] The film was placed on a hot table for heating. Under 365 nm ultraviolet irradiation, the light color changed from red to blue, and the light color changed back to red after the temperature dropped. The light color change showed a significant stimulus response to temperature. Figure 5 The luminescence spectra at different temperatures are shown in Figure 6 . Example 2

[0024] In a 50mL round-bottom flask, 1g acrylamide, 0.008g ammonium persulfate and 0.007g α-thiophenecarbonyltrifluoroacetone were added, dissolved with 9mL deionized water and 1.2mL acetonitrile solvent, placed in a microwave chemical reactor, refluxed at a microwave power of 600W for 7 min, and after the container was naturally cooled to room temperature, precipitated with methanol to obtain polymer A, and then the polymer was washed with methanol for multiple times until the washing liquid was clear, the polymer was taken out and dissolved with 30mL deionized water, and the molar ratio of europium nitrate to α-thiophenecarbonyltrifluoroacetone was controlled to be 1:5, 1:3, 1:2, and 1:1, 0.006~0.03mmol europium nitrate solution was added, the pH was adjusted to neutral with NaOH solution, shaken, and after standing for several minutes, the polymer was precipitated with methanol, and the colloidal solution was dissolved with deionized water to obtain a colloidal solution. 1mL of the colloidal solution was dripped into a circular silica gel mold with a diameter of 2cm, placed in a 40℃ oven, and dried for 24h to obtain a colorful luminescent polymer film.

[0025] When the molar ratio of europium nitrate to α-thiopheneyltrifluoroacetone is 1:1, the prepared polymer film exhibits green, green and purple light emission under excitation at 254nm, 310nm and 365nm wavelengths, respectively; when the ratio is 1:2 and 1:3, it exhibits green, orange-yellow and pink light emission; when the ratio is 1:5, it exhibits yellow, orange and red light emission. Example 3

[0026] In a 50mL round-bottom flask, 1g acrylamide and 0.01g ammonium persulfate were added, and the doping amount of α-thiophenecarbonyltrifluoroacetone was gradually increased from 0.0065g to 0.013g. The mixture was dissolved with 10mL deionized water and 1.5mL acetonitrile solvent, placed in a microwave chemical reactor, and refluxed for 10 min at a microwave power of 375W. After the container was naturally cooled to room temperature, it was precipitated with methanol. The polymer was then washed with methanol several times until the washing liquid was clear. The polymer was taken out and dissolved with 30mL deionized water. According to the molar ratio of europium nitrate to α-thiophenecarbonyltrifluoroacetone of 1:3, the corresponding amount of europium nitrate solution was added, and the pH was adjusted to neutral with NaOH solution. After shaking and standing for several minutes, the polymer was precipitated with methanol, and the colloidal solution was obtained by dissolving with deionized water. 1mL of the colloidal solution was dripped into a circular silica gel mold with a diameter of 2cm, placed in an oven at 40℃, and dried for 24h to obtain a colorful luminescent polymer film.

[0027] When the doping amount of α-thiopheneyltrifluoroacetone is 0.0065g, the prepared polymer film exhibits green, orange-yellow and pink light emission under excitation at wavelengths of 254nm, 310nm and 365nm, respectively; when the doping amount is 0.01g, it exhibits yellow-green, orange-yellow and pink light emission; when the doping amount is 0.013g, it exhibits green, yellow-green and purple light emission.

Claims

1. A method for synthesizing a colorful luminescent polymer film by a microwave method, characterized in that: (1) After acrylamide, ammonium persulfate and α-thenoyltrifluoroacetone are dissolved in a solvent, the mixture is placed in a microwave chemical reactor, and microwave reflux reaction is performed for a certain period of time at a certain microwave power. After cooling to room temperature, the polymer A is precipitated with methanol to obtain the polymer A, and the polymer A is washed until the washing liquid is clear; (2) Dissolving the washed polymer A with deionized water, adding an appropriate amount of europium nitrate solution after dissolution, adjusting the pH to neutral with NaOH solution, shaking, standing for 10 minutes, and precipitating with methanol to obtain polymer B; (3) Dissolve polymer B in deionized water to obtain a colloidal solution, drop the colloidal solution into a circular silicone mold, place it in a 40°C oven, and dry it for 24 hours to obtain a colorful luminescent polymer film.

2. The method for synthesizing a colorful luminescent polymer film using a microwave method according to claim 1, characterized in that The mass ratio of acrylamide, ammonium persulfate, α-thenoyltrifluoroacetone and solvent is 100: (0.5-1.2): (0.5-1.3): (1000-1500).

3. The method for synthesizing a colorful luminescent polymer film using a microwave method according to claim 1, characterized in that The solvent is a mixed solvent of deionized water and acetonitrile, and the volume ratio of deionized water to acetonitrile is 10:1-1.

5.

4. The method for synthesizing a colorful luminescent polymer film using a microwave method according to claim 1, characterized in that The microwave reactor has an output microwave power of 50W to 750W, and the microwave reflux reaction has a reaction time of 3 to 15 minutes.

5. The method for synthesizing a colorful luminescent polymer film using a microwave method according to claim 1, characterized in that The molar ratio of europium nitrate to α-thenoyltrifluoroacetone is 1:1-5.

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