A phosphorescent composite material and its preparation method and application

Abstract

The present invention provides a phosphorescent composite material, a preparation method, and applications thereof. The phosphorescent composite material comprises polylactic acid as a host matrix and ofloxacin carbon quantum dots as guests, macroscopically uniformly dispersed within the host matrix. In the phosphorescent material provided by the present invention, the carbon quantum dots and the polylactic acid matrix form a rigid microenvironment through hydrogen bonds, which stabilizes triplet excitons, reduces non-radiative vibrations, and improves phosphorescence performance. Furthermore, the polylactic acid matrix undergoes a certain degree of cross-linking under ultraviolet light, further stabilizing the microenvironment and enhancing the bonding between the carbon quantum dots and the polylactic acid matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of room temperature phosphorescent materials, and in particular to a phosphorescent composite material and a preparation method and application thereof. Background Art

[0002] Long afterglow materials are a type of photoluminescent material that can store light energy and emit visible light when excited by a light source. Due to their special optical phenomena, they have attracted widespread attention in the fields of luminescent display, information encryption, and biological imaging.

[0003] Carbon quantum dots are an emerging carbon nanomaterial with three-dimensional dimensions of less than 10 nanometers. Some carbon quantum dots exhibit phosphorescent properties when excited by light sources of specific wavelengths. Compared with traditional metal luminescent materials, carbon quantum dots have many advantages such as wide sources, easy modification, excellent luminescent properties, non-toxicity, and excellent biocompatibility. They have good development prospects. Carbon quantum dot phosphorescent materials also have the characteristics of fast response and fast erasure, and have unique advantages when used in information encryption, anti-counterfeiting and other fields.

[0004] One of the existing methods for preparing carbon quantum dot phosphorescent materials is to disperse carbon quantum dots into a matrix, and use the matrix to stabilize the excited triplet state and prevent oxygen quenching to achieve phosphorescent emission. For example, the patent document with application number CN201910026383.2 discloses a method for preparing carbon quantum dots and phosphorescent composite materials thereof. This technical solution uses aniline monomers to prepare water-soluble carbon quantum dots, and mixes the carbon quantum dots with water-soluble polymers in water, and obtains a phosphorescent composite material after drying. At present, carbon quantum dot phosphorescent materials have high requirements for the screening of matrices and carbon quantum dots. The matrix needs to be able to interact with the carbon quantum dots to achieve a stabilizing effect. At the same time, the matrix should also reduce interference with the excitation light source and the fluorescence and phosphorescence generated by the excitation, so that the phosphorescent material has excellent performance in response speed and phosphorescent performance. Few existing phosphorescent materials can meet the above requirements. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a phosphorescent composite material, which is composed of a specific matrix combined with specific carbon quantum dots and has the characteristics of fast response speed and excellent phosphorescent performance.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A phosphorescent composite material comprises polylactic acid as a main matrix and ofloxacin carbon quantum dots as guests dispersed in the main matrix.

[0008] The present invention uses ofloxacin carbon quantum dots as the guest material. The ofloxacin carbon quantum dots can be prepared by a hydrothermal reaction of ofloxacin molecules. The preparation process is simple, the reaction conditions are mild, and the preparation process does not involve the use of organic solvents, thereby having a green and environmentally friendly effect. When carbon quantum dots are determined, it is necessary to select a suitable host matrix to stabilize ofloxacin carbon quantum dots. From the perspective of molecular structure, ofloxacin carbon quantum dots have a large number of hydroxyl groups on their surface. It is an expected means to construct a rigid microenvironment by forming hydrogen bonds with the host matrix. The formation of hydrogen bonds can stabilize triplet excitons, reduce non-radiative vibrations, and improve phosphorescence performance. On this basis, it is also necessary to limit some optical physical parameters of the host matrix according to the application environment of the product. At present, the most mature application environments of carbon quantum dot phosphorescent materials include anti-counterfeiting, information encryption, and optical printing. These application fields usually require phosphorescent materials to be activated by ultraviolet light and release visible phosphorescence. Therefore, the host matrix should avoid interfering with the activation of carbon quantum dots on the one hand, and on the other hand, it should avoid interfering with the outward release of phosphorescence. At the same time, the host matrix should also have a strong physical bonding effect with the carbon quantum dots to improve the practicality of the phosphorescent material. Considering the above points, the inventor has carried out a series of matrix screening based on ofloxacin carbon quantum dots. During the screening process, it was found that some materials that are often used as matrices in the prior art cannot achieve good phosphorescence effects after being combined with ofloxacin carbon quantum dots. For example, when using PVA as the main matrix, the composite material obtained does not reflect corresponding optical properties. FTIR also does not change before and after ultraviolet irradiation. When using boric acid as the main matrix, the luminous intensity of the composite material is weaker, and the composite material itself is a solid powder and cannot be directly used in many cases. After many aspects of comparison, the inventor proposed a scheme in which polylactic acid is the main matrix and ofloxacin carbon quantum dots is the guest. The main absorption band of polylactic acid is the UVB band, and the activation band of ofloxacin carbon quantum dots is the UVA band. Therefore, polylactic acid has a lower absorptivity for the activation light source. The activation efficiency of ofloxacin carbon quantum dots is higher and the response speed is faster. Polylactic acid has good transparency and a lower absorptivity for visible light, so that the phosphorescence emitted by ofloxacin carbon quantum dots in the visible band can be released outwards to a large extent, thereby improving the visual effect of phosphorescence. In addition, the prior art generally believes that ultraviolet light can cause aging of polymer materials and affect the performance of polymer materials. However, the inventors further discovered that polylactic acid will undergo a certain degree of cross-linking under the action of ultraviolet light. This cross-linking phenomenon further stabilizes the microenvironment provided by polylactic acid for ofloxacin carbon quantum dots, improves the stabilizing effect of polylactic acid on triplet excitons, and enhances the binding effect between polylactic acid and ofloxacin carbon quantum dots, giving the phosphorescent material an advantage in practical applications.

[0009] In addition to the advantages in phosphorescence performance mentioned above, the light-printing film material provided by the present invention also has the following advantages: the ofloxacin carbon quantum dots dispersed in the matrix have different decay rates, so that the phosphorescence generated after the excitation stops dynamically changes from yellow to green, and has a unique effect in the field of anti-counterfeiting; the raw material components of the present invention are simple and low-cost, and it is prepared with ofloxacin as the guest material and polylactic acid as the main material. It does not require the addition of other strong fluorescent and phosphorescent substances, does not contain heavy metal elements, is safe and non-toxic, and has good processability. It can be ground into powder for use according to subsequent application requirements.

[0010] Furthermore, the ofloxacin carbon quantum dots are prepared by hydrothermal reaction of ofloxacin molecules.

[0011] Furthermore, the hydrothermal reaction includes the following steps: dispersing ofloxacin evenly in water, placing it in a reactor, heating it at 180-220° C. for 6-8 hours, then placing it in a 1000Da dialysis bag for purification, and freeze-drying to obtain ofloxacin carbon quantum dots.

[0012] Furthermore, in the hydrothermal reaction, the mass ratio of ofloxacin to water is 1:(200-600).

[0013] The ofloxacin carbon quantum dots prepared by the hydrothermal method exhibit excellent excitation in the ultraviolet A band, preferably with a light source in the 365 nm to 425 nm wavelength range. The fluorescence wavelength range produced by excitation is approximately 300 to 600 nm, with a peak at 400 to 500 nm. After excitation ceases, the phosphorescence wavelength range is approximately 400 to 800 nm, with a peak at 500 to 530 nm. This is compatible with the polylactic acid matrix used as the host, meeting the requirements of the application field. Furthermore, the polylactic acid matrix has an excellent stabilizing effect on the ofloxacin carbon quantum dots, and the phosphorescent material can maintain visible phosphorescence for up to approximately 15 seconds after excitation ceases. Measurements show that after 20 seconds of excitation with a 365 nm to 425 nm ultraviolet light source, the maximum phosphorescence lifetime reaches 625 ms, demonstrating excellent phosphorescence performance.

[0014] Furthermore, the mass ratio of polylactic acid to ofloxacin carbon quantum dots in the optically printable film material is 100:(0.1-1). More preferably, the mass ratio of polylactic acid to ofloxacin carbon quantum dots is 100:(0.4-6).

[0015] Another object of the present invention is to provide a method for preparing the above-mentioned phosphorescent composite material, which comprises the following steps: stirring and mixing the polylactic acid and ofloxacin carbon quantum dots in a solvent and then drying the mixture to obtain a light-printable film material.

[0016] Furthermore, the organic solvent is selected from one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and 1,4-dioxane (Diox).

[0017] Furthermore, the temperature during the mixing and stirring process is 60-80° C. and the time is 2-4 hours.

[0018] Another object of the present invention is to provide an application of the above phosphorescent composite material in optical printing.

[0019] As an example, the application of the phosphorescent composite material in optical printing may include the following specific application forms:

[0020] ① As a characteristic luminescent material applied to a flexible luminescent film, the phosphorescent composite material is distributed in the flexible luminescent film or dispersed in a certain / certain specific areas of the flexible luminescent film. For example, a flexible luminescent film is prepared with the phosphorescent composite material itself as the main body, or the phosphorescent composite material is applied to a specific area of ​​a flexible medium to form a flexible luminescent film with a characteristic luminescent area.

[0021] ② As a characteristic luminescent material used in printing ink, the printing ink can be applied to a specific area of ​​the medium to form a marker that produces phosphorescence after being excited by ultraviolet light, which can be used for anti-counterfeiting or information encryption.

[0022] ③ As a fast-response characteristic luminescent material used in the surface coating of optoelectronic devices.

[0023] In summary, the application of the present invention can achieve the following beneficial effects:

[0024] 1. In the phosphorescent material provided by the present invention, carbon quantum dots and the polylactic acid matrix form a rigid microenvironment through hydrogen bonds, which can stabilize triplet excitons, reduce non-radiative vibrations, and improve phosphorescence performance. In addition, the polylactic acid matrix can also undergo certain cross-linking under the action of ultraviolet light, which further stabilizes the microenvironment and enhances the bonding effect between the carbon quantum dots and the polylactic acid matrix.

[0025] 2. The phosphorescent material provided by the present invention is prepared with ofloxacin as the guest material and polylactic acid as the main material. It does not require the addition of other strong fluorescent or phosphorescent substances. The raw material components are simple, low cost, easy to process, and do not contain heavy metal elements. It is safe, non-toxic, and has good biodegradability, which conforms to the concept of green environmental protection.

[0026] 3. In the present invention, the ofloxacin carbon quantum dots dispersed in the matrix have different decay rates, so that the phosphorescence generated after the excitation stops changes dynamically from yellow to green, which has a unique effect in the field of anti-counterfeiting.

[0027] 4. The phosphorescent material provided by the present invention can maintain visible phosphorescence for up to about 15 seconds after excitation. According to measurements, after 20 seconds of excitation by an ultraviolet light source with a wavelength of 365 nm~425 nm, the longest phosphorescence lifetime reaches 625 ms, and the phosphorescent performance is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The phosphorescence spectrum curve obtained by exciting the phosphorescent composite materials prepared in Examples 1, 3, and 7;

[0029] Figure 2 The phosphorescence spectrum curves obtained by exciting the phosphorescent composite material prepared in Example 1 with light sources of different wavelengths;

[0030] Figure 3 The phosphorescence spectrum curves obtained by exciting the light-printable film material prepared in Example 8 under different storage conditions;

[0031] Figure 4 The phosphorescence spectrum curves obtained by stimulating the light-printable film material prepared in Example 8 after different storage times;

[0032] Figure 5 The phosphorescence lifetime of the light-printable thin film material prepared in Example 8 under a cycle test;

[0033] Figure 6 The infrared spectra of the light-printable film material prepared in Example 8 before and after excitation are shown;

[0034] Figure 7 The infrared spectra of the thin film material prepared in the comparative example before and after excitation are shown;

[0035] Figure 8 This is a phosphorescent photograph of the light-printable film material prepared in Example 8. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0039] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0040] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0041] S3. Add 1.5 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0042] Example 2

[0043] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0044] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0045] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0046] S3. Add 1.5 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0047] Example 3

[0048] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0049] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0050] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0051] S3. Add 0.3 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0052] Example 4

[0053] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0054] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0055] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0056] S3. Add 0.6 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMSO into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0057] Example 5

[0058] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0059] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0060] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0061] S3. Add 1.2 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0062] Example 6

[0063] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0064] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0065] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0066] S3. Add 1.8 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0067] Example 7

[0068] This embodiment provides a phosphorescent composite material and a preparation method thereof, and the specific steps are as follows:

[0069] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0070] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0071] S3. Add 3.0 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80° C. for 3 h, and then dry the mixture to obtain a phosphorescent composite material.

[0072] Example 8

[0073] This embodiment provides a light-printable thin film material and a preparation method thereof, and the specific steps are as follows:

[0074] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0075] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0076] S3. Add 1.5 mg ofloxacin carbon quantum dots, 300 mg of polylactic acid, and 10 mL of DMF into a flask, stir at 80°C for 3 h, then coat the mixture onto a flat glass dish and dry at 80°C to obtain a light-printable film material.

[0077] Example 9

[0078] This embodiment also provides the application of the optical printing film material in embodiment 8 in the optical printing process:

[0079] The above-mentioned light-printing film material is fixed, a screen printing plate is arranged above the light-printing film material, and an ultraviolet light source is arranged above the screen printing plate. The ultraviolet light irradiated by the ultraviolet light source passes through the screen printing plate and acts on the light-printing film material. Under the restriction of the screen printing plate, the ultraviolet light source irradiates a specific area of ​​the light-printing film material, so that a pattern corresponding to the mesh shape of the screen printing plate is formed in the irradiated area.

[0080] Comparative Example

[0081] This comparative example provides a thin film material and a preparation method thereof, and the specific steps are as follows:

[0082] S1. Take 100 mg ofloxacin as the guest material precursor, add it to 40 mL of deionized water, and disperse it evenly by ultrasonication. Then transfer it to a heating box and heat it at 200°C for 6 hours to obtain a hydrothermal mixture;

[0083] S2. The hydrothermal mixture was transferred to a 1000 Da dialysis bag and dialyzed for 12 h, followed by freeze-drying to obtain ofloxacin carbon quantum dots;

[0084] S3. Add 1.5 mg ofloxacin carbon quantum dots, 300 mg of PVA, and 10 mL of DMF to a flask, stir at 80°C for 3 h, then coat the mixture on a flat glass dish and dry at 80°C to obtain a light-printable film material.

[0085] Performance testing:

[0086] ① Influence of the ratio of polylactic acid and ofloxacin carbon quantum dots:

[0087] The phosphorescent composite materials prepared in Examples 1, 3, 4, 5, 6, and 7 were taken, and 365 nm ultraviolet light was used as the excitation light source. The phosphorescent luminescence spectrum generated after the excitation stopped was recorded, and the phosphorescent state was observed with the naked eye. The results showed that visible phosphorescence could be observed in the range of 100: (0.1-1) of the ratio of polylactic acid to ofloxacin carbon quantum dots, and when the ratio of polylactic acid to ofloxacin carbon quantum dots in the phosphorescent composite material was around 100:0.5 (i.e., Examples 1, 5, and 6), the phosphorescent composite material had the highest luminescence intensity. Figure 1 The phosphorescence spectra of Examples 1, 3, and 7 are shown. The one with the higher peak in the spectra is Example 1, and the one with the lower peak is Examples 3 and 7. It is obvious that the luminescence intensity of Example 1 is significantly higher than that of Examples 3 and 7. The lower luminescence intensity of Example 3 should be due to insufficient concentration of carbon quantum dots, while the reason for Example 7 should be that the concentration of carbon quantum dots is too high, resulting in aggregation and quenching.

[0088] ②Influence of excitation light source wavelength

[0089] Figure 2 From left to right in the figure, the phosphorescence spectra of the phosphorescent composite material prepared in Example 1 under excitation light sources of 310nm, 365nm, 395nm, and 425nm are shown. It can be seen from the figure that when 365nm ultraviolet light is used as the excitation light source, the phosphorescence has a wider wavelength range, which is beneficial to improving the visual effect of the phosphorescence.

[0090] ③ Stable performance

[0091] (1) The optical printing film material prepared in Example 8 was taken and divided into two groups. The first group was immersed in deionized water at room temperature for 7 days and then returned to room temperature for drying. The second group was heated at 80°C until the film underwent glass transition and then returned to room temperature for drying. Using 365nm ultraviolet light as the excitation light source, the phosphorescence spectra of the two groups of films were recorded. The results are as follows: Figure 3 As shown, Figure 3 The light-printable film material provided by the present invention can maintain its phosphorescence properties to a large extent after being exposed to high humidity and high temperature environments. Therefore, the present invention has good stability, a wide range of applicable scenarios, and good application prospects.

[0092] (2) The light-printable film material prepared in Example 8 was stored at room temperature and in a dry environment. The phosphorescence properties of the film were tested after different storage times. Figure 4 As shown, Figure 4 This indicates that the optical printing film material provided by the present invention has a good storage life.

[0093] ④ Cycle performance

[0094] The light-printable film material prepared in Example 8 was irradiated with 356 nm ultraviolet light as the excitation light source for 20 seconds. After the phosphorescence disappeared, the film was restored by fumigation with water vapor. The above steps were then repeated to analyze the phosphorescence lifetime of each round of experiments. The results are as follows: Figure 5 As shown, Figure 5 This indicates that the light-printable film material provided by the present invention can still maintain a long phosphorescence life after cyclic luminescence and has good cyclic performance.

[0095] ⑤ Comparison and reference

[0096] The film materials prepared in Example 8 and the comparative example were taken to observe the phosphorescence state after ultraviolet light excitation, and the infrared spectra before and after excitation were measured. The results are as follows: Figure 6 and Figure 7 As shown, Figure 7 It shows that the film material prepared in the comparative example has almost no change after ultraviolet irradiation and fails to show phosphorescence performance, while the film material prepared in Example 8 has obvious change characteristics. Figure 8 The phosphorescence photograph of the thin film material prepared in Example 8 is also shown. Therefore, the host matrix and the guest of the phosphorescent composite material provided by the present invention have other positive interactions in addition to forming hydrogen bonds, so that the phosphorescent composite material exhibits excellent phosphorescent properties.

[0097] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A phosphorescent composite material, characterized in that: The invention comprises polylactic acid as a main matrix and ofloxacin carbon quantum dots as guests dispersed in the main matrix.

2. The phosphorescent composite material according to claim 1, characterized in that: The ofloxacin carbon quantum dots are formed by a hydrothermal reaction of ofloxacin molecules.

3. The phosphorescent composite material according to claim 2, characterized in that: The hydrothermal reaction includes the following steps: Ofloxacin was evenly dispersed in water, placed in a reactor, heated at 180-220°C for 6-8 hours, then placed in a 1000Da dialysis bag for purification, and freeze-dried to obtain ofloxacin carbon quantum dots.

4. The phosphorescent composite material according to claim 3, characterized in that: In the hydrothermal reaction step, the mass ratio of ofloxacin to water is 100:(20~60).

5. The phosphorescent composite material according to claim 1, characterized in that: The mass ratio of polylactic acid and ofloxacin carbon quantum dots is 100:(0.1~1).

6. The phosphorescent composite material according to claim 5, characterized in that: The mass ratio of polylactic acid and ofloxacin carbon quantum dots is 100:(0.4~0.6).

7. The method for preparing the phosphorescent composite material according to any one of claims 1 to 6, characterized in that: The polylactic acid and ofloxacin carbon quantum dots are stirred and mixed in a solvent, and then dried to obtain a phosphorescent composite material.

8. The method for preparing the phosphorescent composite material according to claim 7, wherein: The solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, and 1,4-dioxane.

9. The method for preparing the phosphorescent composite material according to claim 7, wherein: The temperature during the mixing and stirring process is 60~80℃ and the time is 2~4h.

10. Use of the phosphorescent composite material according to any one of claims 1 to 6 in optical printing.

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