A method for synthesizing multicolored luminescent polymer films using microwave technology

Abstract

This invention relates to a method for synthesizing multicolored luminescent polymer films using a microwave approach. The method first involves dissolving acrylamide, ammonium persulfate, and α-thiophenecarboxylic acid trifluoroacetone in a solvent, then refluxing the mixture under microwave power. After cooling to room temperature, polymer A is precipitated with methanol. Polymer A is then dissolved in deionized water, europium nitrate solution is added, the pH is adjusted to neutral, the mixture is shaken, and after standing, polymer B is precipitated with methanol. Finally, polymer B is dissolved in deionized water to obtain a colloidal solution. The colloidal solution is dropped into a silicone mold and dried to obtain the multicolored luminescent polymer film. This invention provides a simple, convenient, and rapid preparation method that does not require inert gas protection and can complete polymerization within minutes, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to a method for synthesizing multicolored luminescent polymer films using a microwave method, belonging to the field of organic luminescent material preparation. Background Technology

[0002] In recent years, room-temperature phosphorescence (RTP) materials have attracted great attention from scientists. Phosphorescent materials emit light during photoexcitation and for a certain period after photoexcitation ceases, such as the glow of a fluorescent pearl, and can be used as display and lighting materials. Currently, phosphorescent materials mainly include inorganic compounds, metal complexes, pure organic compounds, and polymers. Among them, organic polymer phosphorescent materials have advantages such as good flexibility, ductility, processability, plasticity, high electron mobility, low toxicity, good biocompatibility, environmental friendliness, and low cost, making them suitable for various organic optoelectronic flexible materials. The strategies for constructing organic polymer room-temperature phosphorescent materials mainly involve host-guest interactions and hydrogen bonding, molecular assembly, and ionic bonding interactions. Currently, 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), poly(p-phenylene sulfonate) (PSS), and sodium polystyrene sulfonate. The amide groups in the polyacrylamide structure readily form intramolecular and intermolecular hydrogen bonds, effectively restricting molecular and polymer movement and suppressing nonradiative transitions. Simultaneously, the N and O atoms favor n-π transitions. * Transitions and spin-orbit coupling enable efficient room-temperature phosphorescence. Therefore, organic room-temperature phosphorescent polymers based on polyacrylamide have been extensively explored and studied in recent years.

[0003] Because room-temperature phosphorescent materials are sensitive to temperature, oxygen, and humidity, the realization of room-temperature phosphorescence requires strict control of oxygen and humidity. 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 polymers, are mostly synthesized under conditions of dehydrated organic solvents and inert gases. Typically, they are prepared using conventional heating methods via solution free radical polymerization. During polymerization, the formation of linear polymers increases the viscosity of the reaction system, or the formation of network polymers makes the reaction system gel-like. Both of these will prevent further polymerization of monomers, leading to a decrease in conversion rate and affecting the further improvement of the degree of polymerization. Microwaves are a special type of high-frequency energy. In polar solvent systems, microwave energy has strong penetrating power, accelerating the violent movement of solvent and solute molecules while also exerting a deep heating effect on the molecules in the system, i.e., a "thermal effect," allowing the reaction to complete in a short time. In solution polymerization, microwave methods can overcome the shortcomings of traditional heating methods. They can cause solvents, monomers, polymers and other molecules in the system to absorb high microwave energy and move violently, which can significantly accelerate the reaction rate, improve the reaction conversion rate, and complete the polymerization in a short time, and obtain polymers with large molecular weights.

[0004] Currently, the fluorescence emission of polyacrylamide room-temperature phosphorescent materials is primarily blue-violet light. To enrich the fluorescence emission, this invention introduces red-light rare-earth europium. First, a polyacrylamide polymer containing α-thiophenecarboxyltrifluoroacetone ligands is prepared via free radical polymerization using a microwave reactor. Then, rare-earth europium ions (Eu) are used... 3+ By coordinating rare earth europium with β-diketone groups in the polymer, the resulting polymer film material exhibits different luminescence colors under different excitation wavelengths. This color emission, controlled within the 260nm–400nm range, achieves full-color emission from blue to red light. After the ultraviolet lamp is turned off, a color-changing afterglow is observed. Furthermore, the film shows a significant response to temperature-induced color changes. The preparation method of this invention is simple, convenient, and rapid, requiring no inert gas protection; polymerization can be completed in minutes. The prepared polymer material possesses excellent luminescent properties and has broad application prospects. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing multicolored luminescent polymer films using a microwave method.

[0006] The technical solution adopted to achieve the purpose of this invention is as follows:

[0007] A method for synthesizing multicolored luminescent polymer films using a microwave method, characterized in that:

[0008] 1. Acrylamide, ammonium persulfate and α-thiophenecarboxyltrifluoroacetone were dissolved in a solvent and placed in a microwave chemical reactor. The mixture was refluxed under a certain microwave power for a certain time. After cooling to room temperature, polymer A was precipitated with methanol. Polymer A was washed until the washing liquid was clear.

[0009] The mass ratio of acrylamide, ammonium persulfate, α-thiophenecarboxyltrifluoroacetone, and solvent is 100:(0.5~1.2):(0.5~1.3):(1000~1500).

[0010] The solvent is a mixture of deionized water and acetonitrile, with a volume ratio of deionized water to acetonitrile of 10:1 to 1.5.

[0011] The aforementioned microwave power has an output power of 50W~750W;

[0012] The microwave reflux reaction has a reaction time of 3 to 15 minutes.

[0013] 2. Dissolve the washed polymer A in deionized water, add an appropriate amount of europium nitrate solution, adjust the pH to neutral with NaOH solution, shake, let stand for a few minutes, and then precipitate with methanol to obtain polymer B.

[0014] The addition of an appropriate amount of europium nitrate, wherein the molar ratio of europium nitrate to α-thiophenecarboxylic acid trifluoroacetone is 1:1~5.

[0015] 3. Dissolve polymer B in deionized water to obtain a colloidal solution. Drop the colloidal solution into a circular silicone mold and place it in an oven at 40°C for 24 hours to obtain the multicolored luminescent polymer film of the present invention.

[0016] The present invention has the following advantages:

[0017] 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.

[0018] 2. The preparation is rapid using a microwave chemical reactor, and polymerization can be completed in just a few minutes.

[0019] 3. The polymer thin film material prepared by the present invention exhibits different emission colors under different excitation wavelengths. It can be controlled in the range of 260nm~400nm by changing the excitation wavelength, realizing full-color emission of polymer thin film from blue light to red light, and achieving color-changing afterglow after the ultraviolet lamp is turned off.

[0020] 4. The polymer film material prepared by this invention exhibits a significant light color change response to temperature. Placing the film at high temperature causes a color change from red to blue, and the color changes back to red when the temperature returns to room temperature. Attached Figure Description

[0021] Figure 1 The emission colors of the polymer film prepared in Example 1 under excitation at 254 nm, 310 nm, 365 nm and 400 nm are shown.

[0022] Figure 2 The afterglow color of the polymer film prepared in Example 1 changed over time after the light source was turned off following excitation at 310 nm.

[0023] Figure 3 These are spectra at different time delays.

[0024] Figure 4 The color of the polymer film prepared in Example 1 changes with temperature. Detailed Implementation

[0025] The present invention will be further described below through specific embodiments, but these specific embodiments do not limit the scope of protection of the present invention in any way.

[0026] Example 1

[0027] In a 50 mL round-bottom flask, 1 g of acrylamide, 0.01 g of ammonium persulfate, and 0.0065 g of α-thiophenecarboxylic acid trifluoroacetone were added and dissolved in 9 mL of deionized water and 1 mL of acetonitrile. The mixture was placed in a microwave chemical reactor and refluxed at 600 W for 7.5 min. After the container cooled naturally to room temperature, it was precipitated with methanol to obtain polymer A. Polymer A was then washed several times with methanol until the washings were clear. Polymer A was then dissolved in 30 mL of deionized water, and 0.01 mmol of europium nitrate solution was added. The pH was adjusted to neutral with NaOH solution, shaken, and allowed to stand for 10 minutes. Polymer B was then precipitated with methanol and dissolved in deionized water to obtain a colloidal solution. 1 mL of the colloidal solution was dropped into a 2 cm diameter circular silicone mold and dried in a 40 °C oven for 24 h to obtain a multicolored luminescent polymer film.

[0028] The prepared polymer films exhibited green, orange, red, and blue luminescence under excitation at wavelengths of 254 nm, 310 nm, 365 nm, and 400 nm, respectively. Figure 1 .

[0029] After irradiating the polymer film with a 310 nm ultraviolet lamp for a period of time, the light source was turned off. The film emitted afterglow, and the color of the afterglow changed over time, exhibiting a color-changing afterglow from yellow to cyan and then to green. Figure 2 The time-delay spectra of the polymer are as follows: Figure 3 .

[0030] The thin film was heated on a hot stage and exhibited a color change from red to blue under 365 nm ultraviolet irradiation. The color changed back to red upon cooling, demonstrating a clear stimulus response to temperature changes. The color change was as follows: Figure 4 .

[0031] Example 2

[0032] In a 50 mL round-bottom flask, 1 g of acrylamide, 0.008 g of ammonium persulfate, and 0.007 g of α-thiophenecarboxylic acid trifluoroacetone were added and dissolved in 9 mL of deionized water and 1.2 mL of acetonitrile. The mixture was placed in a microwave chemical reactor and refluxed at 600 W for 7 min. After the container cooled naturally to room temperature, the polymer was precipitated with methanol to obtain polymer A. The polymer was then washed several times with methanol until the washing liquid was clear. The polymer was then dissolved in 30 mL of deionized water. The molar ratio of europium nitrate to α-thiophenecarboxylic acid trifluoroacetone was controlled at 1:5, 1:3, 1:2, and 1:1. 0.006–0.03 mmol of europium nitrate solution was added, and the pH was adjusted to neutral with NaOH solution. The mixture was shaken and allowed to stand for several minutes. The resulting polymer was precipitated with methanol and dissolved in deionized water to obtain a colloidal solution. 1 mL of the colloidal solution was dropped into a 2 cm diameter circular silicone mold and placed in a 40 °C oven to dry for 24 h to obtain a multicolored luminescent polymer film.

[0033] When the molar ratio of europium nitrate to α-thiophenecarboxylic acid trifluoroacetone is 1:1, the polymer film prepared exhibits green, green and purple luminescence under excitation at wavelengths of 254 nm, 310 nm and 365 nm, respectively; when the ratio is 1:2 and 1:3, it exhibits green, orange-yellow and pink luminescence; when the ratio is 1:5, it exhibits yellow, orange and red luminescence.

[0034] Example 3

[0035] In a 50 mL round-bottom flask, 1 g of acrylamide and 0.01 g of ammonium persulfate were added. The doping amount of α-thiophenecarboxylic acid trifluoroacetone was gradually increased from 0.0065 g to 0.013 g. The mixture was dissolved in 10 mL of deionized water and 1.5 mL of acetonitrile. The mixture was placed in a microwave chemical reactor and refluxed at a microwave power of 375 W for 10 min. After the container cooled naturally to room temperature, methanol was used to precipitate the polymer. The polymer was then washed several times with methanol until the washing liquid was clear. The polymer was removed and dissolved in 30 mL of deionized water. Europium nitrate solution was added according to a molar ratio of europium nitrate to α-thiophenecarboxylic acid trifluoroacetone of 1:3. The pH was adjusted to neutral with NaOH solution. The mixture was shaken and allowed to stand for several minutes. The resulting polymer was precipitated with methanol and dissolved in deionized water to obtain a colloidal solution. 1 mL of the colloidal solution was dropped into a circular silicone mold with a diameter of 2 cm and placed in an oven at 40 °C for 24 h to obtain a multicolored luminescent polymer film.

[0036] When the doping amount of α-thiophenecarboxyltrifluoroacetone is 0.0065 g, the prepared polymer film exhibits green, orange-yellow and pink luminescence under excitation at wavelengths of 254 nm, 310 nm and 365 nm, respectively; when the doping amount is 0.01 g, it exhibits yellow-green, orange-yellow and pink luminescence; and when the doping amount is 0.013 g, it exhibits green, yellow-green and purple luminescence.

Claims

1. A method for synthesizing multicolored luminescent polymer films using a microwave method, characterized in that: (1) Acrylamide, ammonium persulfate and α-thiophenecarboxylic acid trifluoroacetone were dissolved in a solvent and placed in a microwave chemical reactor for microwave reflux reaction for a certain time. After cooling to room temperature, polymer A was obtained by precipitation with methanol. Polymer A was washed until the washing liquid was clear. (2) Dissolve the washed polymer A in deionized water, add europium nitrate solution after dissolution, adjust the pH to neutral with NaOH solution, shake, let stand for 10 minutes, and then precipitate 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 and place it in an oven at 40°C for 24 hours to obtain a multicolored luminescent polymer film. The mass ratio of acrylamide, ammonium persulfate, α-thiophenecarboxyltrifluoroacetone, and solvent is 100:(0.5~1.2):(0.5~1.3):(1000~1500). The molar ratio of europium nitrate to α-thiophenecarboxylic acid trifluoroacetone is 1:1~5.

2. The method for synthesizing multicolored luminescent polymer films using a microwave method according to claim 1, characterized in that... The solvent is a mixture of deionized water and acetonitrile, with a volume ratio of deionized water to acetonitrile of 10:1 to 1.

5.

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

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