Room temperature phosphorescent material, preparation method and room temperature phosphorescent photocuring material

Abstract

This invention discloses a room-temperature phosphorescent material with the following general molecular formula and its preparation method: wherein A is selected from any one of hydrogen atom, alkyl, halogen, alkoxy, nitro, cyano, amino, aldehyde, and phenyl; and B and C are respectively selected from aromatic rings, heterocyclic aromatic rings, or their derivatives. This invention also discloses a room-temperature phosphorescent photocurable material containing this room-temperature phosphorescent material. This invention adds organic light-emitting molecules with doped room-temperature phosphorescence as functional materials to a transparent photocurable resin. The photocurable resin, as a polymer matrix, provides a rigid environment to restrict the vibration and rotation of the light-emitting molecules, thus suppressing non-radiative transitions. It also isolates the triplet excitons generated by the excitation from oxygen and moisture, achieving long-life room-temperature phosphorescence for applications such as temperature sensing and information display. Furthermore, the light-emitting molecules in the resin can act as light absorbers, reducing the light transmittance of the resin while ensuring photocuring efficiency and improving printing accuracy.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a room temperature phosphorescent material, a method for preparing the material, and a room temperature phosphorescent 3D photocurable material containing the material. Background Technology

[0002] 3D printing technology is a new type of additive manufacturing technology. Unlike traditional subtractive manufacturing or equal-material manufacturing, additive manufacturing allows for rapid prototyping and highly flexible processing. It can produce high-precision and complex structures that are impossible or extremely difficult to process using traditional manufacturing methods. It mainly relies on 3D modeling software to manufacture solid objects by processing them layer by layer. The entire process has advantages such as economy, speed, and high customizability. It is currently widely used in fields such as industrial design, art design, biomedicine, cultural relic protection, jewelry, architecture, automobiles, and aerospace.

[0003] In 3D printing technology, digital light processing 3D printing technology has gained widespread attention due to its fast printing speed, precise processing accuracy, and high-quality formed surface. Accuracy is a key indicator in 3D printing, mainly limited by equipment, materials, and parameters. The materials used in digital light processing 3D printing technology are photocurable materials. Its main mechanism is as follows: under illumination of a specific wavelength of light (generally ultraviolet light), the photoinitiator in the photocurable material generates active groups such as free radicals or cations, initiating the polymerization of monomers and diluents in the photocurable material, achieving a solid-liquid transition, polymerizing the liquid into a supporting structure, and ultimately creating a three-dimensional solid. To improve printing accuracy, it is necessary to reasonably control the efficiency of photoinitiation and the transmission depth of the light source. If the efficiency of the photoinitiator is too low, polymerization cannot be fully initiated. If the efficiency of the photoinitiator is too high, the curing process will be too fast, the heat release will be too intense, and internal stress will be concentrated, causing deformation. If the light transmittance is too high, it will lead to overexposure, which will seriously affect the printing accuracy. The current common solution is to add a light absorber to the photocurable material. While ensuring the photocuring efficiency, the light absorber absorbs excess ultraviolet light, reduces the light transmittance of the photocurable material, and ultimately improves the printing accuracy.

[0004] Phosphorescence refers to a slow, natural emission phenomenon, while room-temperature phosphorescence (Room-Temperature Phosphorescence) refers to phosphorescence that occurs at room temperature. The specific process is as follows: luminescent molecules absorb photons and enter the excited singlet state S under the illumination of an excitation source. n (n≥1), and then transforms into an excited triplet state T through an intersystem crossing process. nAfterward, the triplet exciton slowly transitions back to the ground state, and the light emitted by the triplet exciton returning to the ground state is phosphorescence. Compared with traditional fluorescence, room-temperature phosphorescent materials have a longer luminescence lifetime, a larger Stokes shift, and are sensitive to environmental factors such as oxygen and temperature, making them suitable for use as stimulus-responsive materials in sensors. Phosphorescence also has high luminescence intensity and long lifetime, so it is often used in advanced information encryption and display.

[0005] Traditional research on room-temperature phosphorescent materials focuses on metal complexes and crystalline materials, primarily due to the strong spin-orbit coupling of metal complexes and the ability of crystalline materials to suppress nonradiative transitions and quenching. Purely organic amorphous phosphorescent materials, however, have a simple preparation process and do not rely on heavy metals, thus holding great promise for applications. However, their unique formation process limits their application to inert conditions such as low temperature and oxygen-free environments. Polymers, with their molecular weight and long-chain structure, can provide a rigid environment, directly restricting the vibration, rotation, and collision of luminescent molecules. They can also isolate the environment from oxygen and moisture, preventing the quenching of excited excitons and extending the lifetime of triplet excitons in organic compounds at room temperature. Furthermore, flexible polymers possess low toxicity, low cost, and excellent processability, making polymer-based room-temperature phosphorescent materials irreplaceable in materials science.

[0006] However, commonly used light absorbers have limited functions, only reducing the light transmittance of photocurable resins. Photocurable materials formulated with commonly used light absorbers can only be used to manufacture some structural components and cannot achieve specific functions such as light, electricity, magnetism, heat, chemistry, and biochemistry. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention proposes a room-temperature phosphorescent material, a method for preparing the material, and a room-temperature phosphorescent 3D photocurable material containing the material. This invention adds the room-temperature phosphorescent material to a transparent photocurable resin to achieve long-life room-temperature phosphorescence, which can be used in fields such as temperature sensing and information display. Furthermore, the room-temperature phosphorescent material can act as a light absorber in the resin, reducing the resin's light transmittance while ensuring photocuring efficiency and improving 3D printing accuracy.

[0008] According to one aspect of the present invention, a room-temperature phosphorescent material is provided, characterized by the following general molecular structural formula:

[0009]

[0010] Where A is selected from any one of hydrogen atom, alkyl, halogen, alkoxy, nitro, cyano, amino, aldehyde, and phenyl.

[0011] B and C can be the same or different, and are respectively selected from aromatic rings, aromatic heterocycles or their derivatives.

[0012] Furthermore, B and C are preferably: benzophenone group, diphenyloxyphosphine group, diphenylamino group, aniline group, and phenyl ketone, etc.

[0013] Specifically, the specific structural formula of the room-temperature phosphorescent material includes, but is not limited to:

[0014]

[0015] According to another aspect of the present invention, a method for preparing the room temperature phosphorescent material as described above is provided, the method comprising: mixing a carbazole derivative with derivatives of B and C in an organic solvent at a molar ratio of 1:0.8 to 1:3; adding an appropriate amount of alkali (with a molar ratio of 1:0.8 to 1:3 with the carbazole derivative); adding a small amount of catalyst; removing oxygen; heating the reaction solution to reflux temperature and stirring (generally for 4 to 36 hours, preferably 18 hours); stopping the reaction; purifying the solution by vacuum distillation, extraction filtration, drying filtration, and silica gel column chromatography to finally obtain the final product.

[0016] The organic solvents mentioned include, but are not limited to: dichloromethane, toluene, acetone, tetrahydrofuran, chloroform, N,N-dimethylformamide, and dimethyl sulfoxide.

[0017] Alkalis include, but are not limited to: potassium hydroxide, potassium carbonate, and aluminum chloride.

[0018] According to another aspect of the present invention, a room-temperature phosphorescent photocurable material is provided, characterized in that it comprises a doped room-temperature phosphorescent material as described above and a photosensitive resin matrix, wherein the mass ratio of the room-temperature phosphorescent material to the photosensitive resin matrix is ​​1:10000 to 1:10. Using techniques such as photopolymerization 3D printing, room-temperature phosphorescent photocurable materials can be used to fabricate integrated structural and functional devices, applicable to fields such as information encryption, bioimaging, information display, temperature sensing, humidity sensing, and oxygen sensing.

[0019] The photosensitive resin matrix includes, but is not limited to: acrylate photosensitive resin, methacrylate photosensitive resin, vinyl photosensitive resin, vinyl ether photosensitive resin, epoxy photosensitive resin, unsaturated polyester photosensitive resin, epoxy acrylate photosensitive resin, polyurethane acrylate photosensitive resin, polyester acrylate photosensitive resin, polyether acrylate photosensitive resin, pure acrylic resin photosensitive resin, silicone resin photosensitive resin, epoxy photosensitive resin, and aliphatic acrylate photosensitive resin.

[0020] This invention incorporates organic light-emitting molecules with room-temperature phosphorescence as functional materials into a transparent photocurable resin. The photocurable resin, acting as a polymer matrix, provides a rigid environment to restrict the vibrational and rotational thermal motions of the light-emitting molecules, thus suppressing non-radiative transitions. It also isolates the triplet excitons generated during excitation from oxygen and moisture, achieving long-lifetime room-temperature phosphorescence for applications in temperature sensing and information display. Furthermore, the light-emitting molecules in the resin act as light absorbers, reducing the resin's light transmittance while maintaining photocuring efficiency, thereby improving printing accuracy. The strategy is ingeniously designed, the process is simple, and the steps are easily controlled. This room-temperature phosphorescent photocurable material achieves both high-precision printing and room-temperature phosphorescence, truly realizing structural-functional integration. It has a very broad application prospect in information encryption, information display, temperature sensing, humidity sensing, and oxygen sensing. Attached Figure Description

[0021] Figure 1 These are illustrations showing the accuracy test images of the room temperature phosphorescent curable material 2 provided by this invention and ordinary transparent resin.

[0022] Figure 2 The diagram illustrates the change in curing depth of the photocurable material before and after the addition of the light absorber provided by this invention under different curing times.

[0023] Figure 3 This is the spectrum of the room temperature phosphorescent photocurable material 2 of the present invention.

[0024] Figure 4 The images show the fine structure of the room-temperature phosphorescent curable material of this invention, manufactured by 3D printing, emitting phosphorescence under natural light, ultraviolet light, and with the ultraviolet lamp turned off.

[0025] Figure 5 The images show the afterglow of a spiral pipe prepared by 3D printing using the room temperature phosphorescent photocurable material 1 of the present invention, when liquids at different temperatures are introduced into it. Detailed Implementation

[0026] To better understand the purpose, technical solution, and advantages of this invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] Example 1:

[0028] The method for synthesizing the room-temperature phosphorescent material in Example 1 is as follows:

[0029]

[0030] The first step was the synthesis of the intermediate 3,6-dibromo-9-ethylcarbazole (EtCzBr). Under air, 3,6-dibromo-9H-carbazole (3.00 g, 9.23 mmol), bromoethane (1.06 g, 9.69 mmol), and KOH (3.00 g, 13.85 mmol) were added to a 250 mL flask, followed by 30 mL of acetone. The reaction mixture was heated to reflux and stirred for 18 hours. After cooling to room temperature, the reaction mixture was distilled under reduced pressure to obtain a dry solid. The solid was dissolved in dichloromethane and extracted by washing with saturated brine. The organic phase was subjected to vacuum distillation to obtain a crude product. The crude product was then purified using a mixed solvent of dichloromethane and n-hexane (1 / 10, v / v) as the mobile phase and silica gel as the stationary phase. Vacuum distillation and drying yielded 2.23 g of a white solid, 3,6-dibromo-9-ethylcarbazole, with a yield of 68.43%. This solid was used as a starting material to synthesize the final product, EtCzBP. The synthesis of EtCzBP followed the procedure for PhCzBP, ultimately yielding 0.31 g of a yellow solid, with a yield of 66.85%.

[0031] Example 2:

[0032] The method for synthesizing the room-temperature phosphorescent material in Example 2 is as follows:

[0033]

[0034] Under an argon atmosphere, 3,6-dibromo-9-phenyl-9H-carbazole (1.50 g, 3.74 mmol), phenyl(4-(4,4,5,5-tetramethyl-1,3,2-dioxaneborane-2-yl)phenyl) methyl ketone (2.77 g, 8.98 mmol), and K₂CO₃ (3.10 g, 22.44 mmol) were added to a dry 250 mL two-necked flask. A mixture of tetrahydrofuran (21 mL) and deionized water (7 mL) was then added until the solid was completely dissolved. Finally, the catalyst Pd(PPh₃)₄ (0.21 g, 0.187 mmol) was added. The reaction mixture was heated to reflux temperature and stirred for 18 h before the reaction was stopped. After cooling to room temperature, the reaction mixture was distilled under reduced pressure to obtain a dry solid. The dry solid was dissolved in dichloromethane, washed and extracted with saturated brine, and the organic phase was distilled under reduced pressure to obtain the crude product. The crude product was separated and purified using a mixed solvent of dichloromethane and n-hexane (1 / 1, v / v) as the mobile phase and silica gel as the stationary phase. After vacuum distillation and drying, 0.90 g of a white solid was obtained, with a yield of 39.86%.

[0035] Example 3:

[0036] This embodiment provides a method for preparing a room temperature phosphorescent photocurable material.

[0037] Preparation of room temperature phosphorescent curable material 1: Weigh 1g of the room temperature phosphorescent material prepared in Example 2 and 100g of the purchased Next Dent dental model resin into a reagent bottle, add a magnetic stir bar, and stir magnetically for 5 hours. The light absorber is fully dissolved, and the resulting transparent solution is the room temperature phosphorescent curable material 1.

[0038]

[0039] Example 4:

[0040] This embodiment provides a method for preparing a room temperature phosphorescent photocurable material.

[0041] Preparation of room temperature phosphorescent curable material 2: Weigh 1g of the room temperature phosphorescent material prepared in Example 1 and 100g of purchased PMMA transparent resin into a reagent bottle, add a magnetic stir bar, and stir magnetically for 5 hours. The light absorber is fully dissolved, and the resulting transparent solution is the room temperature phosphorescent curable material 2. Figure 3 This is the spectrum of room temperature phosphorescent photocurable material 2. The shaded area represents the phosphorescence spectrum, the long dash represents the photoluminescence spectrum before photoactivation, and the short dash represents the photoluminescence spectrum after photoactivation.

[0042] Example 5:

[0043] In this embodiment, the functional structure is printed using the room temperature phosphorescent curing material 1 described above.

[0044] The prepared room-temperature phosphorescent photocurable material 1 was added to a DLP photocurable printer. Printing parameters were tested experimentally, with a model slice layer thickness of 50 μm and an exposure intensity of 20 mW / cm². 2 With an exposure time of 3 seconds, a series of high-precision structures are printed, such as... Figure 4 and Figure 5 As shown. Figure 4 These are actual images of the fine structure of the room-temperature phosphorescent curable material of this invention, manufactured by 3D printing, emitting phosphorescence under natural light, ultraviolet light, and with the ultraviolet lamp turned off. Figure 5 The images show the afterglow of a spiral pipe prepared by 3D printing using the room temperature phosphorescent photocurable material 1 of the present invention, when liquids at different temperatures are introduced into it.

[0045] These materials possess the ability to sense external environmental factors, such as temperature, humidity, and oxygen concentration. As temperature increases, the molecular thermal motion of the light absorber intensifies, leading to an increase in the proportion of non-radiative transitions and a decrease in radiative transitions, resulting in weaker phosphorescence intensity and a shorter lifespan. Similarly, as ambient humidity increases, water molecules disrupt the hydrogen bonds between the polymer and the light absorber, weakening the interaction between them. This also increases the molecular mobility of the light absorber, ultimately weakening the intensity and shortening the lifespan of room-temperature phosphorescence. Therefore, it can be used to fabricate multimodal smart sensors, achieving integrated structure and function. Furthermore, with the support of 3D printing technology, the fabrication of these devices is more convenient, and structural optimization can further improve their sensing performance. Room-temperature phosphorescent photocurable materials are also suitable for information display, information encryption, smart sensors, organic electroluminescent devices, and organic solar cells, showing great application potential.

[0046] Related feature tests

[0047] 1. The effect of functionalized light absorbers on printing accuracy

[0048] The effect of light absorbers on printing accuracy is demonstrated through two experiments.

[0049] Experiment 1: First, under a uniform light source intensity, the change in curing depth of the photocurable material before and after the addition of a light absorber was tested at different exposure times. The change in curing depth was used to evaluate the projection depth of ultraviolet light, thereby assessing the impact of the light absorber on printing accuracy. Results are as follows: Figure 2 As shown, the black dots represent the curing depth of ordinary transparent resin, the pentagram represents the curing depth of room temperature phosphorescent curing material 2, and the two enlarged symbols represent the limiting exposure depth corresponding to the minimum exposure time. The addition of the light absorber significantly reduces the curing depth of the curing material and lowers its light transmittance.

[0050] Experiment 2: Test models with different structural features and sizes were printed using photocurable materials before and after the addition of a light absorber. The printing parameter was uniformly set to the final exposure time of the photocurable material. The results are as follows: Figure 1 As shown, the first row contains micrographs of the accuracy test model printed with transparent resin without added light absorber, and the second row contains micrographs of the accuracy test model printed with room temperature phosphorescent photocurable material 2 (scale bar: 2mm) prepared by adding room temperature phosphorescent light absorber to transparent resin. In the first row, only 3mm and 2mm horizontal through-holes were successfully printed with the photocurable material without light absorber, while smaller sizes were blocked. The photocurable material with added light absorber successfully printed 400μm through-holes, demonstrating a significant improvement in printing accuracy. Other structures, such as cantilever beams, also demonstrate that the addition of room temperature phosphorescent light absorber greatly improves printing accuracy and quality.

[0051] 2. Temperature sensing characteristics of room temperature phosphorescence

[0052] Experiment 3: The printed structure was passed through liquids at different temperatures, and then the lifetime and intensity of room-temperature phosphorescence were collected after ultraviolet light stimulation. The results are as follows: Figure 5 As shown, the higher the temperature, the lower the phosphorescence intensity and the shorter the lifespan.

[0053] In this invention, organic light-emitting molecules with room-temperature phosphorescence doped with phosphorescence are added as functional materials to a transparent photocurable resin. The photocurable resin, acting as a polymer matrix, provides a rigid environment to restrict the vibrational and rotational thermal motions of the light-emitting molecules, thereby suppressing non-radiative transitions. It also isolates the triplet excitons generated during excitation from oxygen and moisture, thus achieving a long-lifetime afterglow for applications in temperature sensing and information display. Furthermore, the light-emitting molecules in the resin can act as light absorbers, controlling the transmission depth of ultraviolet light within the resin. This reduces the resin's light transmittance while maintaining photocuring efficiency, thereby improving printing accuracy.

[0054] This invention utilizes 3D printing technology to fabricate room-temperature phosphorescent photocurable materials into devices with integrated structure and function, enabling free-form manufacturing. These devices can be used as stimulus-responsive functional materials in fields such as information encryption, information display, bioimaging, temperature sensing, humidity sensing, and oxygen sensing.

[0055] Specifically, room-temperature phosphorescent (RTP) structural-functional integrated devices can be used as stimulus-responsive materials for information encryption and display. They can also be used in bioimaging, temperature sensing, humidity sensing, and oxygen sensing.

Claims

1. A room-temperature phosphorescent material, characterized in that... The general molecular formula is as follows: Where A is selected from any one of halogen, nitro, cyano, amino, and phenyl; B is the same as C and is selected from benzophenone.

2. The room-temperature phosphorescent material according to claim 1, wherein the specific structural formula of the room-temperature phosphorescent material is as follows: 。 3. A room temperature phosphorescent photocurable material, characterized in that... The material includes a doped room-temperature phosphorescent material according to claim 1 and a photosensitive resin matrix, wherein the mass ratio of the room-temperature phosphorescent material to the photosensitive resin matrix is ​​1:10000 to 1:

10.

4. The room temperature phosphorescent photocurable material according to claim 3, wherein the photosensitive resin matrix is ​​any one of the following: acrylate photosensitive resin, vinyl photosensitive resin, vinyl ether photosensitive resin, epoxy photosensitive resin, unsaturated polyester photosensitive resin, polyurethane acrylate photosensitive resin, polyester acrylate photosensitive resin, polyether acrylate photosensitive resin, or silicone photosensitive resin.

5. The room temperature phosphorescent photocurable material according to claim 4, wherein the acrylate photosensitive resin includes pure acrylic photosensitive resin, aliphatic acrylate photosensitive resin or methacrylate photosensitive resin.

6. The room temperature phosphorescent photocurable material according to claim 4, wherein the epoxy photosensitive resin includes epoxy acrylate photosensitive resin.

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