Self-cleaning fluorine-containing copolymer with adjustable color-changing response time, film and preparation method and application of self-cleaning fluorine-containing copolymer and film

Abstract

The invention provides a self-cleaning fluorine-containing copolymer with adjustable color-changing response time, a film and a preparation method and application of the self-cleaning fluorine-containing copolymer and the film, and belongs to the technical field of functional film materials. The self-cleaning fluorine-containing copolymer disclosed by the invention is prepared from the following raw materials: N-(2-methacryloyloxyethyl)-4-bromine-1, 8-naphthalimide, methyl methacrylate, hydroxyethyl methylacrylate, dodecafluoroheptyl methacrylate and ethylene glycol dimethacrylate. According to the self-cleaning fluorine-containing copolymer with adjustable color-changing response time, multi-stage luminescence evolution of blue light, red light and near white light under ultraviolet light is realized for the first time, the color-changing response time of each stage can be accurately controlled by adjusting the composition of the copolymer, and the technical bottlenecks that an existing color-changing material is single in response mode and uncontrollable in time are solved; according to the invention, the self-cleaning characteristic of the perfluoro side chain and the photoresponse color-changing function of naphthalimide are organically fused, so that the film has the self-cleaning performance and the visual feedback function of environmental stimulation.

Description

Technical Field

[0001] This invention relates to the field of functional thin film materials technology, and in particular to a self-cleaning fluorinated copolymer with adjustable color-changing response time, a thin film, its preparation method, and its application. Background Technology

[0002] As materials technology develops towards "functional integration, controllable performance, and intelligent application," polymer materials with multiple responses and practical protective properties have become a core requirement in complex scenarios. Photochromic materials achieve reversible control over the color and intensity of light emission by inducing changes in molecular structure or aggregation state through light stimulation, and have irreplaceable application value in fields such as intelligent displays, environmental sensing, and high-end anti-counterfeiting.

[0003] Naphthalimide derivatives are preferred fluorophores for constructing photoresponsive materials due to their high quantum yield of luminescence, good photostability, and easy structural modification. However, existing naphthalimide-based color-changing materials rely primarily on single-mode regulation through intramolecular charge transfer, π-π stacking, or hydrogen bonding. The color-changing mode is limited to a single-color-to-single-color response, providing only simple light signal feedback and failing to meet the needs of multi-dimensional identification and dynamic monitoring. More importantly, their response time is determined by the inherent molecular structure, lacking effective means for precise control through material composition design. Some technologies utilize external conditions such as temperature and humidity for adjustment, but these are complex to operate, have limited applicability, and are difficult to adapt to the flexible response rate requirements of industry.

[0004] Fluoropolymers, due to the low surface energy of their perfluorinated side chains, impart self-cleaning properties and are widely used in protective coatings. The core value of introducing dodecafluoroheptyl methacrylate (DOMA) into the copolymer system lies in the significant polar gradient and microphase separation structure formed by its strong hydrophobicity and the hydrophilicity of hydroxyethyl methacrylate (HMA). This microstructure provides a unique confined microenvironment for the naphthalimide luminescent units, whose aggregation state and molecular mobility can be finely controlled by adjusting the ratio of fluorinated monomers to HMA. This mechanism is crucial for multi-stage color change and tunable response time, directly affecting the energy transfer pathways of luminescent molecules, excitoassociate formation kinetics, and oxygen diffusion behavior in the film, thus determining the initiation and evolution rate of each stage of color change.

[0005] Existing technologies integrating self-cleaning and color-changing functions mostly employ physical blending or simple compounding methods, failing to utilize the polarity differences between monomers for synergistic design. This results in poor compatibility of functional components, weak interfacial bonding, and insufficient performance synergy. For example, the random distribution of fluorinated segments disrupts the orderly aggregation of luminescent groups, leading to a decrease in luminescence efficiency; the random distribution of luminescent units interferes with the regular arrangement of fluorinated segments, weakening the self-cleaning effect and ultimately causing performance loss, failing to meet practical requirements. Furthermore, existing multifunctional materials suffer from significant shortcomings in practical performance. Their preparation often relies on complex molecular design, multi-step synthesis processes, or expensive specialized equipment, resulting in high costs and low production efficiency, severely restricting large-scale industrial applications.

[0006] Although existing research has attempted to integrate photoresponsive color change and self-cleaning functions, no technology has yet been able to achieve a synergistic balance between multi-stage color change, adjustable response time, and self-cleaning performance, film-forming properties, adhesion, and stability by precisely controlling the ratio of fluorinated monomers to polar monomers such as hydroxyethyl methacrylate. Furthermore, there is a lack of solutions that can achieve synergistic optimization of these functions through simple monomer combinations and mild processes.

[0007] Therefore, developing a fluorinated copolymer film that can achieve multi-stage color change and adjustable response time by controlling the copolymer composition, and which also has excellent self-cleaning properties, film-forming properties, substrate adhesion and chemical stability, and providing a simple, cost-effective and easily scalable preparation method, can fill the gap in existing technology, meet the urgent needs of multiple fields, and has important theoretical research value and broad market application prospects. Summary of the Invention

[0008] The purpose of this invention is to address the problems of existing color-changing materials having a single response mode and non-adjustable time, self-cleaning materials having a single function and lacking intelligence, and multifunctional polymers having poor integration and complex processes. This invention provides a self-cleaning fluorinated copolymer with adjustable color-changing response time, a film, its preparation method and application, achieving a technological breakthrough in multi-characteristic synergy, controllable performance and easy scalability of the process.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a self-cleaning fluorinated copolymer with adjustable color-changing response time, wherein the structural formula of the self-cleaning fluorinated copolymer is Formula 1: Formula 1; Where m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer, m, j, k, and l are independent numbers greater than 0, n is a number greater than or equal to 0, and m+n+j+k+l=100.

[0010] Preferably, the raw materials for preparing the self-cleaning fluorinated copolymer include N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, and ethylene glycol dimethacrylate.

[0011] The present invention also provides a method for preparing the self-cleaning fluorinated copolymer with adjustable color-changing response time, comprising the following steps: N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, ethylene glycol dimethacrylate, initiator and solvent are mixed, and the mixture is polymerized under a protective atmosphere to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0012] Preferably, the molar ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, and ethylene glycol dimethacrylate is 0.52:11.7~19.5:2.6~7.8:2.6~7.8:0~0.78.

[0013] Preferably, the molar ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide to the initiator is 0.52:0.22~0.3, and the molar volume ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide to the solvent is 0.52 mmol:20~50 mL; The initiator is azobisisobutyronitrile, and the solvent comprises tetrahydrofuran and ethyl acetate, with a volume ratio of tetrahydrofuran to ethyl acetate of 10~20:10~30.

[0014] Preferably, the polymerization reaction is a free radical polymerization reaction, the polymerization temperature is 63~68℃, and the polymerization time is 20~24h.

[0015] The present invention also provides a method for preparing a self-cleaning fluorinated copolymer film with adjustable color change response time using the aforementioned self-cleaning fluorinated copolymer with adjustable color change response time. The method involves mixing the self-cleaning fluorinated copolymer with adjustable color change response time and a solvent to obtain a mixture; the mixture is then coated onto the surface of a substrate and dried to obtain a self-cleaning fluorinated copolymer film with adjustable color change response time.

[0016] Preferably, the mass-to-volume ratio of the self-cleaning fluorinated copolymer with adjustable color-changing response time to the solvent is 10-20 mg: 1 mL; the coating method includes spin coating, drop coating, or spray coating; the drying temperature is 55-75°C, and the drying time is 20-36 h.

[0017] The present invention also provides a self-cleaning fluorinated copolymer film with adjustable color-changing response time prepared by the method.

[0018] This invention also provides the application of the self-cleaning fluorinated copolymer film with adjustable color-changing response time in the fields of high-end anti-counterfeiting, smart response coatings, and optoelectronic devices.

[0019] The beneficial effects of this invention are: 1) The color-changing response time adjustable self-cleaning fluorinated copolymer of the present invention achieves for the first time a multi-stage luminescence evolution of "blue light → red light → near white light" under ultraviolet light. By adjusting the copolymer composition, the color-changing response time of each stage can be precisely controlled, which solves the technical bottleneck of the single response mode and uncontrollable time of the existing color-changing materials.

[0020] 2) This invention organically integrates the self-cleaning properties of perfluorinated side chains with the photoresponsive color-changing function of naphthalimide, enabling the film to possess both self-cleaning properties and a visual feedback function for environmental stimuli. Compared to single-function materials, it achieves a synergistic effect of "self-cleaning protection + intelligent monitoring," expanding its application value in high-end anti-counterfeiting, intelligent coating, and other fields.

[0021] 3) The film prepared by the present invention through the hydrogen bonding between hydroxyl groups and the substrate, the film-forming properties of methyl methacrylate and the crosslinking network of ethylene glycol dimethacrylate exhibits excellent film-forming properties, substrate adhesion and chemical stability, which solves the problem of insufficient stability caused by poor performance synergy of existing multifunctional materials.

[0022] 4) This invention uses free radical polymerization, which has mild reaction conditions, a stable reaction process, and readily available raw materials. The polymerization reaction time is moderate, the production efficiency is high, the production cost is significantly reduced, and it is easy to scale up production, thus having broad industrialization prospects. Attached Figure Description

[0023] Figure 1 The infrared spectra of P1CO, P2CO and P3CO obtained in Examples 1 to 3 are shown. Figure 2 The 1H NMR spectra of P1CO, P2CO, and P3CO obtained in Examples 1 to 3 are shown below. Figure 3 The images show the actual self-cleaning effects of P1CO, P2CO, and P3CO obtained in Examples 1 to 3. Figure 4 The steady-state emission spectrum of P1CO obtained in Example 1 as a function of UV irradiation time; Figure 5 The steady-state emission spectrum of P2CO obtained in Example 2 as a function of UV irradiation time; Figure 6The steady-state emission spectrum of P3CO obtained in Example 3 as a function of UV irradiation time; Figure 7 This is a three-dimensional fluorescence spectrum of P1CO obtained in Example 1 as a function of UV irradiation time; Figure 8 This is a three-dimensional fluorescence spectrum of P2CO obtained in Example 2 as a function of UV irradiation time; Figure 9 This is a three-dimensional fluorescence spectrum of P3CO obtained in Example 3 as a function of UV irradiation time. Detailed Implementation

[0024] This invention provides a self-cleaning fluorinated copolymer with adjustable color-changing response time, wherein the structural formula of the self-cleaning fluorinated copolymer is Formula 1: Formula 1; Where m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer, m, j, k, and l are independent numbers greater than 0, n is a number greater than or equal to 0, and m+n+j+k+l=100.

[0025] In this invention, the molar ratio of m, n, j, k and l is preferably 55~78:0~3:10~30:2:10~30, and more preferably 58~75:1~2:15~25:2:15~25.

[0026] In this invention, the raw materials for preparing the self-cleaning fluorinated copolymer preferably include N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, and ethylene glycol dimethacrylate.

[0027] The present invention also provides a method for preparing the self-cleaning fluorinated copolymer with adjustable color-changing response time, comprising the following steps: N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, ethylene glycol dimethacrylate, initiator and solvent are mixed, and the mixture is polymerized under a protective atmosphere to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0028] In this invention, the molar ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, and ethylene glycol dimethacrylate is preferably 0.52:11.7~19.5:2.6~7.8:2.6~7.8:0~0.78, more preferably 0.52:12.5~18:3.5~6.5:3.5~6.5:0.2~0.6, and even more preferably 0.52:14.5~16:4.5~5.5:4.5~5.5:0.3~0.5.

[0029] In this invention, the molar ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide to the initiator is preferably 0.52:0.22~0.3, more preferably 0.52:0.24~0.28, and even more preferably 0.52:0.26; the molar volume ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide to the solvent is preferably 0.52mmol:20~50mL, more preferably 0.52mmol:30~45mL, and even more preferably 0.52mmol:35~40mL. The initiator is preferably azobisisobutyronitrile, and the solvent comprises tetrahydrofuran and ethyl acetate, wherein the volume ratio of tetrahydrofuran to ethyl acetate is preferably 10~20:10~30, and more preferably 10~15:15~25.

[0030] In this invention, the polymerization reaction is preferably a free radical polymerization reaction, the polymerization temperature is preferably 63~68℃, more preferably 64~67℃, even more preferably 65~66℃, and the polymerization time is preferably 20~24h, more preferably 21~23h, even more preferably 22h.

[0031] In this invention, the polymerization reaction is preferably carried out in a side-mounted flask. Before the polymerization reaction, the side-mounted flask is preferably deoxygenated. The deoxygenation step is as follows: after adding the raw materials, high-purity nitrogen gas is introduced and purged for 5 to 10 minutes to replace the air in the flask, and then the flask is sealed.

[0032] In this invention, after the polymerization reaction is completed, drying is preferably carried out to obtain a self-cleaning fluorinated copolymer with adjustable color change response time. The drying is preferably done by blowing air. The drying temperature is preferably 55~65℃, more preferably 60℃, and the drying time is preferably 24~48h, more preferably 30~40h, and more preferably 34~36h.

[0033] The present invention also provides a method for preparing a self-cleaning fluorinated copolymer film with adjustable color change response time using the aforementioned self-cleaning fluorinated copolymer with adjustable color change response time. The method involves mixing the self-cleaning fluorinated copolymer with adjustable color change response time and a solvent to obtain a mixture; the mixture is then coated onto the surface of a substrate and dried to obtain a self-cleaning fluorinated copolymer film with adjustable color change response time.

[0034] In this invention, the mass-to-volume ratio of the self-cleaning fluorinated copolymer with adjustable color-changing response time to the solvent is preferably 10-20 mg:1 mL, more preferably 13-16 mg:1 mL; the solvent is preferably tetrahydrofuran.

[0035] In this invention, the coating method preferably includes spin coating, drop coating or spray coating; the drying temperature is preferably 55~75℃, more preferably 58~68℃, more preferably 60~65℃, and the drying time is preferably 20~36h, more preferably 22~30h, more preferably 24~26h; the drying is preferably blower drying.

[0036] The present invention also provides a self-cleaning fluorinated copolymer film with adjustable color-changing response time prepared by the method.

[0037] This invention also provides the application of the self-cleaning fluorinated copolymer film with adjustable color-changing response time in the fields of high-end anti-counterfeiting, smart response coatings, and optoelectronic devices.

[0038] The self-cleaning fluorinated copolymer film with adjustable color-changing response time obtained by this invention exhibits a multi-stage luminescence behavior that evolves from blue light to red light and then to near-white light under ultraviolet light irradiation. The color-changing response time of each stage can be controlled and adjusted by the copolymer composition. At the same time, the material has self-cleaning properties and excellent film-forming properties, substrate adhesion and chemical stability, making it suitable for high-end anti-counterfeiting, smart coating and optoelectronic device fields.

[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1

[0041] The structural formula of the self-cleaning fluorinated copolymer with adjustable color-changing response time obtained in this embodiment is as follows: ; Where m is 75, n is 3, j is 10, k is 2, and l is 10, m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer.

[0042] The preparation steps of the self-cleaning fluorinated copolymer are as follows: 0.52 mmol N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, 19.5 mmol methyl methacrylate, 2.6 mmol hydroxyethyl methacrylate, 2.6 mmol dodecafluoroheptyl methacrylate, 0.78 mmol ethylene glycol dimethacrylate, 0.26 mmol azobisisobutyronitrile, 10 mL tetrahydrofuran, and 30 mL ethyl acetate were placed in a 250 mL side-mounted flask. High-purity nitrogen gas was introduced and purged for 8 min to replace the air in the flask, which was then sealed. Free radical polymerization was carried out at 65 °C under nitrogen atmosphere for 24 h. After that, air was introduced, and the reaction solution was poured into a 50 mL centrifuge tube and dried in a forced-air drying oven at 60 °C for 36 h to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0043] 10 mg of a self-cleaning fluorinated copolymer with adjustable color-changing response time was mixed with 1 mL of tetrahydrofuran. The mixture was then applied to a 2 cm × 10 cm glass substrate using a dropper and dried in a forced-air drying oven at 60 °C for 24 h to obtain a self-cleaning fluorinated copolymer film, denoted as "P1CO".

[0044] Example 2

[0045] The structural formula of the self-cleaning fluorinated copolymer with adjustable color-changing response time obtained in this embodiment is as follows: ; Where m is 55, n is 3, j is 30, k is 2, and l is 10, m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer.

[0046] The preparation steps of the self-cleaning fluorinated copolymer are as follows: 0.52 mmol N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, 11.7 mmol methyl methacrylate, 7.8 mmol hydroxyethyl methacrylate, 2.6 mmol dodecafluoroheptyl methacrylate, 0.78 mmol ethylene glycol dimethacrylate, 0.26 mmol azobisisobutyronitrile, 10 mL tetrahydrofuran, and 30 mL ethyl acetate were placed in a 250 mL side-mounted flask. High-purity nitrogen gas was introduced and purged for 5 min to replace the air in the flask, which was then sealed. Free radical polymerization was carried out at 65 °C under nitrogen atmosphere for 24 h. After that, air was introduced, and the reaction solution was poured into a 50 mL centrifuge tube and dried in a forced-air drying oven at 60 °C for 36 h to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0047] 10 mg of a self-cleaning fluorinated copolymer with adjustable color-changing response time was mixed with 1 mL of tetrahydrofuran. The mixture was then applied to a 2 cm × 10 cm glass substrate using a dropper and dried in a forced-air drying oven at 60 °C for 24 h to obtain a self-cleaning fluorinated copolymer film, denoted as "P2CO".

[0048] Example 3

[0049] The structural formula of the self-cleaning fluorinated copolymer with adjustable color-changing response time obtained in this embodiment is as follows: ; Where m is 55, n is 3, j is 10, k is 2, and l is 30, m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer.

[0050] The preparation steps of the self-cleaning fluorinated copolymer are as follows: 0.52 mmol N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, 11.7 mmol methyl methacrylate, 2.6 mmol hydroxyethyl methacrylate, 7.8 mmol dodecafluoroheptyl methacrylate, 0.78 mmol ethylene glycol dimethacrylate, 0.26 mmol azobisisobutyronitrile, 10 mL tetrahydrofuran, and 30 mL ethyl acetate were placed in a 250 mL side-mounted flask. High-purity nitrogen gas was introduced and purged for 10 min to replace the air in the flask, which was then sealed. Free radical polymerization was carried out at 65 °C under nitrogen atmosphere for 24 h. After that, air was introduced, and the reaction solution was poured into a 50 mL centrifuge tube and dried in a forced-air drying oven at 60 °C for 36 h to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0051] 10 mg of a self-cleaning fluorinated copolymer with adjustable color-changing response time was mixed with 1 mL of tetrahydrofuran. The mixture was then applied to a 2 cm × 10 cm glass substrate using a dropper and dried in a forced-air drying oven at 60 °C for 24 h to obtain a self-cleaning fluorinated copolymer film, denoted as "P3CO".

[0052] Example 4

[0053] The structural formula of the self-cleaning fluorinated copolymer with adjustable color-changing response time obtained in this embodiment is as follows: ; Where m is 78, n is 0, j is 10, k is 2, and l is 10, m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer.

[0054] The preparation steps of the self-cleaning fluorinated copolymer are as follows: 0.52 mmol N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, 19.5 mmol methyl methacrylate, 2.6 mmol hydroxyethyl methacrylate, 2.6 mmol dodecafluoroheptyl methacrylate, 0.26 mmol azobisisobutyronitrile, 10 mL tetrahydrofuran, and 15 mL ethyl acetate were placed in a 100 mL side-mounted flask. High-purity nitrogen gas was introduced and purged for 8 min to replace the air in the flask, which was then sealed. Free radical polymerization was carried out at 65 °C under nitrogen atmosphere for 24 h. After that, air was introduced, and the reaction solution was poured into a 50 mL centrifuge tube and dried in a forced-air drying oven at 60 °C for 36 h to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0055] 20 mg of a self-cleaning fluorinated copolymer with adjustable color-changing response time was mixed with 1 mL of tetrahydrofuran. The mixture was then applied to a 2 cm × 10 cm glass substrate using a dropper and dried in a forced-air drying oven at 60 °C for 24 h to obtain a self-cleaning fluorinated copolymer film, denoted as "P1".

[0056] Example 5

[0057] The structural formula of the self-cleaning fluorinated copolymer with adjustable color-changing response time obtained in this embodiment is as follows: ; Where m is 58, n is 0, j is 30, k is 2, and l is 10, m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer.

[0058] The preparation steps of the self-cleaning fluorinated copolymer are as follows: 0.52 mmol N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, 11.7 mmol methyl methacrylate, 7.8 mmol hydroxyethyl methacrylate, 2.6 mmol dodecafluoroheptyl methacrylate, 0.26 mmol azobisisobutyronitrile, 10 mL tetrahydrofuran, and 15 mL ethyl acetate were placed in a 100 mL side-mounted flask. High-purity nitrogen gas was introduced and purged for 8 min to replace the air in the flask, which was then sealed. Free radical polymerization was carried out at 65 °C under nitrogen atmosphere for 24 h. After that, air was introduced, and the reaction solution was poured into a 50 mL centrifuge tube and dried in a forced-air drying oven at 60 °C for 36 h to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0059] 20 mg of a self-cleaning fluorinated copolymer with adjustable color-changing response time was mixed with 1 mL of tetrahydrofuran. The mixture was then applied to a 2 cm × 10 cm glass substrate using a dropper and dried in a forced-air drying oven at 60 °C for 24 h to obtain a self-cleaning fluorinated copolymer film, denoted as "P2".

[0060] Example 6

[0061] The structural formula of the self-cleaning fluorinated copolymer with adjustable color-changing response time obtained in this embodiment is as follows: ; Where m is 58, n is 0, j is 10, k is 2, and l is 30, m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer.

[0062] The preparation steps of the self-cleaning fluorinated copolymer are as follows: 0.52 mmol N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, 11.7 mmol methyl methacrylate, 2.6 mmol hydroxyethyl methacrylate, 7.8 mmol dodecafluoroheptyl methacrylate, 0.26 mmol azobisisobutyronitrile, 10 mL tetrahydrofuran, and 15 mL ethyl acetate were placed in a 100 mL side-mounted flask. High-purity nitrogen gas was introduced and purged for 8 min to replace the air in the flask, which was then sealed. Free radical polymerization was carried out at 65 °C under nitrogen atmosphere for 24 h. After that, air was introduced, and the reaction solution was poured into a 50 mL centrifuge tube and dried in a forced-air drying oven at 60 °C for 36 h to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

[0063] 20 mg of a self-cleaning fluorinated copolymer with adjustable color-changing response time was mixed with 1 mL of tetrahydrofuran. The mixture was then applied to a 2 cm × 10 cm glass substrate using a dropper and dried in a forced-air drying oven at 60 °C for 24 h to obtain a self-cleaning fluorinated copolymer film, denoted as "P3".

[0064] The infrared spectra of P1CO, P2CO, and P3CO obtained in Examples 1-3 are shown below. Figure 1 As shown, the 1H NMR spectra of P1CO, P2CO, and P3CO obtained in Examples 1-3 are as follows. Figure 2 As shown.

[0065] The following performance tests were conducted on the self-cleaning fluorinated copolymer films with adjustable color-changing response time obtained in Examples 1 to 3.

[0066] (1) Self-cleaning performance test: Using an oil-based pen, the bottom of P1CO, P2CO, and P3CO were blackened respectively. The test results showed that the ink could be easily wiped off with cotton.

[0067] P1CO, P2CO, and P3CO were placed at a 45° angle, and impurities (dust and sand) were sprinkled on them. Water was then allowed to flow naturally down from the top of the film. The result was that the impurities on P1CO, P2CO, and P3CO were easily removed, and the film remained transparent.

[0068] The self-cleaning effects of P1CO, P2CO, and P3CO obtained in Examples 1-3 are shown in the following figures. Figure 3 As shown.

[0069] (2) Steady-state emission performance test: P1CO, P2CO, and P3CO solid films were irradiated with a 10W UV lamp (365nm) for 0s, 1s, 3s, 5s, and 10s, respectively. The steady-state emission spectra of the films at these time points were measured using a Hitachi F-7100 fluorescence spectrophotometer with an excitation wavelength of 365nm, a slit width Ex / Em of 5 / 2.5nm, a scan speed of 2400nm / min, and a scan voltage of 700V.

[0070] The steady-state emission spectrum of P1CO obtained in Example 1 as a function of UV irradiation time is shown below. Figure 4 As shown; the steady-state emission spectrum of P2CO obtained in Example 2 as a function of UV irradiation time is shown in the figure. Figure 5 As shown; the steady-state emission spectrum of P3CO obtained in Example 3 as a function of UV irradiation time is shown in the figure. Figure 6 As shown. By Figure 4 It can be seen that for P1CO, with prolonged ultraviolet irradiation time, the phosphorescence peak at 550–650 nm increases dramatically after 1 second of irradiation; the fluorescence peak at around 425 nm shows no significant change within 3 seconds of irradiation, but shows a significant increase and redshift after 3 seconds. Figure 5 It can be seen that with the extension of UV irradiation time, the phosphorescence peak of P2CO at 550-650 nm, which had a high initial intensity before irradiation, increased dramatically after 1 second of irradiation; the fluorescence peak at around 425 nm showed no significant change within 3 seconds of irradiation, but showed a significant enhancement and redshift after 3 seconds. Figure 6 It can be seen that as the UV irradiation time of P3CO increases, the phosphorescence peak of 550~650nm slowly increases after 3~5s of irradiation; the fluorescence peak of about 425nm shows a significant increase and red shift after irradiation.

[0071] The differences in the steady-state emission spectra of P1CO, P2CO, and P3CO films under UV irradiation are primarily attributed to the differences in the microenvironment of the naphthalimide luminescent units caused by the controlled ratio of dodecylfluoroheptyl methacrylate to hydroxyethyl methacrylate in the copolymer. This difference regulates the conversion rate from single fluorescence to room-temperature phosphorescence and excitopolymer luminescence, achieving precise tuning of the response time. Specifically, the polar gradient and microphase separation structure formed by the strong hydrophobicity of dodecylfluoroheptyl methacrylate and the hydrophilicity of hydroxyethyl methacrylate control the oxygen diffusion rate by adjusting the hydrophobicity of the film. Furthermore, it regulates the aggregation state and degrees of freedom of naphthalimide molecules by changing the hydroxyethyl methacrylate content and crosslinking density, affecting their π-π stacking degree and excitopolymer formation. Ultimately, this results in a regular difference in the timing of fluorescence peak enhancement and the redshift amplitude. Examples 1-3 fully demonstrate that the present invention can achieve the directional design of the luminescent unit microenvironment through precise control of copolymer composition, thereby achieving controllable regulation of photoresponse dynamics.

[0072] (3) Three-dimensional fluorescence spectroscopy test: P1CO, P2CO, and P3CO solid films were irradiated with an AUX 10W UV lamp for 0s, 20s, 60s, and 120s, respectively. The three-dimensional fluorescence spectra of the films at these time points were measured using a Hitachi F-7100 fluorescence spectrophotometer with an excitation wavelength of 365nm, a slit width Ex / Em of 5 / 2.5nm, a scan speed of 2400nm / min, and a scan voltage of 700V.

[0073] The three-dimensional fluorescence spectrum of P1CO obtained in Example 1 as a function of UV irradiation time is shown below. Figure 7 As shown; the three-dimensional fluorescence spectrum of P2CO obtained in Example 2 as a function of UV irradiation time is shown in the figure. Figure 8 As shown; the three-dimensional fluorescence spectrum of P3CO obtained in Example 3 as a function of UV irradiation time is shown in the figure. Figure 9 As shown. By Figures 7-9 It is evident that as the ultraviolet irradiation time increases, new emission centers continuously emerge for P1CO, P2CO, and P3CO, and the absorption and emission intensity of the core region increases significantly.

[0074] The changes in the three-dimensional fluorescence spectra of P1CO, P2CO, and P3CO films under ultraviolet irradiation are primarily due to the charge transfer interaction between the copolymer molecular chains and the naphthalimide luminescent units. This interaction continuously induces the naphthalimide luminescent units to form excitokines, thereby promoting the generation of new emission centers in the film, and significantly enhancing the absorption and emission intensity of the core emission region.

[0075] This invention achieves a multi-stage luminescence evolution of "blue light → red light → near-white light" under ultraviolet light by precisely controlling the ratio of dodecafluoroheptyl methacrylate to hydroxyethyl methacrylate in the copolymer. New emission centers are continuously formed and the emission intensity of the core region is significantly improved. At the same time, the color change response time is directionally controllable. Furthermore, the fluorinated copolymer film material has self-cleaning properties, excellent film-forming properties, substrate adhesion, and chemical stability, laying a solid foundation for the practical application of this type of material in high-end anti-counterfeiting, intelligent responsive coatings, optoelectronic devices, and other fields.

[0076] The same basic performance tests were performed on the non-crosslinked linear copolymer films (P1, P2, P3) obtained in Examples 4-6. The results showed that, without the addition of ethylene glycol dimethacrylate (crosslinking agent), P1, P2, and P3 could also form films, and under 365nm ultraviolet light irradiation, they all exhibited a multi-stage luminescence phenomenon similar to P1CO, P2CO, and P3CO. This confirms that the core color-changing mechanism of this invention mainly depends on the polarity of the microenvironment constructed by the fluorinated monomer and the hydrophilic monomer, rather than on the crosslinking network. However, compared to P1, P2CO, and P3CO, due to the introduction of the crosslinking network, their films exhibited better solvent resistance, hardness, and luminescence stability than P1, P2, and P3.

[0077] This invention, through the design of a multi-monomer synergistic copolymer system incorporating naphthalimide luminescent units, combined with free radical polymerization and drop-coating film deposition processes, achieves the synergistic integration of multi-stage color change, controllable response time, and self-cleaning functions, providing a key technical solution for the precise preparation and functional optimization of intelligent responsive copolymer films. The film material of this invention, with its core advantages of functional integration and controllable response, can be widely adapted to high-end anti-counterfeiting, intelligent protective coatings, optoelectronic devices, environmental monitoring, and other scenarios, and is particularly suitable for industrial and consumer applications with stringent requirements for material functional synergy, response accuracy, and long-term service stability.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A self-cleaning fluorinated copolymer with adjustable color-changing response time, characterized in that, The structural formula of the self-cleaning fluorinated copolymer is Formula 1: Formula 1; Where m, n, j, k, and l represent the molar percentage of each structural unit in the fluorinated copolymer, m, j, k, and l are independent numbers greater than 0, n is a number greater than or equal to 0, and m+n+j+k+l=100.

2. The self-cleaning fluorinated copolymer with adjustable color-changing response time according to claim 1, characterized in that, The raw materials for preparing the self-cleaning fluorinated copolymer include N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, and ethylene glycol dimethacrylate.

3. The method for preparing the self-cleaning fluorinated copolymer with adjustable color-changing response time as described in claim 1 or 2, characterized in that, It includes the following steps: N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthalimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, ethylene glycol dimethacrylate, initiator and solvent are mixed, and the mixture is polymerized under a protective atmosphere to obtain a self-cleaning fluorinated copolymer with adjustable color change response time.

4. The preparation method according to claim 3, characterized in that, The molar ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide, methyl methacrylate, hydroxyethyl methacrylate, dodecafluoroheptyl methacrylate, and ethylene glycol dimethacrylate is 0.52:11.7~19.5:2.6~7.8:2.6~7.8:0~0.

78.

5. The preparation method according to claim 4, characterized in that, The molar ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide to the initiator is 0.52:0.22~0.3, and the molar volume ratio of N-(2-methacryloyloxyethyl)-4-bromo-1,8-naphthylimide to the solvent is 0.52 mmol:20~50 mL. The initiator is azobisisobutyronitrile, and the solvent comprises tetrahydrofuran and ethyl acetate, with a volume ratio of tetrahydrofuran to ethyl acetate of 10~20:10~30.

6. The preparation method according to claim 4 or 5, characterized in that, The polymerization reaction is a free radical polymerization reaction, the polymerization temperature is 63~68℃, and the polymerization time is 20~24h.

7. The method for preparing a self-cleaning fluorinated copolymer film with adjustable color-change response time according to claim 1 or 2, characterized in that, A self-cleaning fluorinated copolymer with adjustable color-changing response time is mixed with a solvent to obtain a mixture; the mixture is coated onto the surface of a substrate and then dried to obtain a self-cleaning fluorinated copolymer film with adjustable color-changing response time.

8. The method according to claim 7, characterized in that, The mass-to-volume ratio of the self-cleaning fluorinated copolymer with adjustable color-changing response time to the solvent is 10~20mg:1mL; the coating method includes spin coating, drop coating or spray coating; the drying temperature is 55~75℃ and the drying time is 20~36h.

9. The self-cleaning fluorinated copolymer film with adjustable color-changing response time prepared by the method of claim 7 or 8.

10. The application of the color-changing response time adjustable self-cleaning fluorinated copolymer film of claim 9 in the fields of high-end anti-counterfeiting, smart response coating and optoelectronic devices.

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