Polymer with thermally enhanced long afterglow characteristic as well as preparation method and application thereof

Abstract

The invention discloses a polymer with a thermally enhanced long afterglow characteristic as well as a preparation method and application thereof, and belongs to the technical field of organic long afterglow polymers. The polymer is prepared by heating and melting an electron donor organic matter and an electron acceptor organic matter, and the electron donor organic matter comprises a triphenylamine group and a boronic acid pinacol ester group connected with the triphenylamine group. The benzene ring, connected with the pinacol borate group, in the triphenylamine group is connected with at least one benzene ring in the remaining benzene rings in the triphenylamine group through a carbon-carbon single bond; and the electron acceptor organic matter is polyethylene glycol terephthalate. After the polymer is irradiated by ultraviolet light or sunlight, long afterglow emission with the peak value located at 520 nm (green light) or 560 nm (yellow-green light) can be generated, and the long afterglow intensity of the polymer can be remarkably increased along with rising of the environment temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of organic long - afterglow polymers, and particularly relates to a polymer with thermally enhanced long - afterglow characteristics, a preparation method thereof, and an application thereof. Background Art

[0002] As a unique photophysical phenomenon different from traditional transient fluorescence, long - afterglow luminescence enables the excited - state carriers to continue radiative recombination even after the excitation is stopped, and the luminescence duration can reach from several milliseconds to several hours. This luminescence behavior with adjustable time dimension makes it a frontier research field. Compared with transient fluorescence, long - afterglow materials can effectively eliminate the interference of background fluorescence and improve the signal - to - noise ratio by extending the detectable luminescence signal time. Therefore, it shows excellent advantages in the fields of bio - fluorescence imaging, multi - level anti - counterfeiting systems, and sensitive optical sensing, promoting the research and development process of new, highly efficient, and stable long - afterglow material systems.

[0003] Inorganic long - afterglow systems based on trap engineering exhibit multi - mode optical response characteristics such as photoluminescence, long - afterglow luminescence, and optically stimulated luminescence by constructing shallow and deep energy - level traps. However, when these materials are applied in practice, they face significant technical bottlenecks: firstly, the high synthesis temperature limits the processing performance of the materials and results in high preparation costs; secondly, the brittleness of the materials restricts the integration of flexible devices; thirdly, the high heavy - metal content is likely to cause biocompatibility risks. Therefore, current research is committed to developing new long - afterglow materials prepared by low - temperature solution methods, which are flexible, processable, and environmentally friendly, in order to achieve stable and reliable optical sensing applications.

[0004] Organic long - afterglow materials show the potential to replace inorganic systems due to their adjustable mechanical properties, convenience of low - temperature solution processing, and excellent biosecurity. However, the non - radiative relaxation of triplet excitons induced by environmental oxygen / water easily quenches the luminescence, resulting in the room - temperature long - afterglow duration being mostly limited to the millisecond to second level. Recently, through molecular engineering strategies such as constructing exciplex - type donor - acceptor systems, the organic afterglow lifetime has been successfully extended to the hour level. However, such materials still face core problems such as insufficient photo - stability and poor environmental tolerance. Some researchers have significantly improved the environmental stability of the materials through strategies such as developing p - type doping systems, constructing eutectic composite materials, and introducing rigid matrix structures. It is worth noting that there is still an obvious gap with inorganic materials in terms of thermal stability: the increase in temperature intensifies molecular thermal motion, leading to the dissipation of excited - state energy through non - radiative channels; at the same time, irreversible damages such as molecular configuration distortion, isomerization, and conjugated backbone fracture induced by high temperature change the luminescence energy - level distribution and quench the luminescence. The above factors jointly pose a severe challenge to the luminescence stability of organic long - afterglow materials at room temperature. Summary of the Invention

[0005] In order to solve the problems of poor stability and quenching luminescence upon heating in the prior art for organic long persistent phosphorescent materials, one of the objectives of the present invention is to provide a method for preparing a polymer with thermally enhanced long persistent phosphorescent properties.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: A method for preparing a polymer with thermally enhanced long persistent phosphorescent properties is provided, and the preparation method includes the following steps: Step 1: Grind an electron donor organic compound and an electron acceptor organic compound together with an organic solvent to obtain a mixed powder. Step 2: Heat the mixed powder to a transparent molten state and then immediately cool it to room temperature to obtain a polymer with thermally enhanced long persistent phosphorescent properties. The electron donor organic compound includes a triphenylamine group, a pinacol borate group connected to the triphenylamine group, and the benzene ring in the triphenylamine group connected to the pinacol borate group is connected to at least one of the remaining benzene rings in the triphenylamine group through a carbon-carbon single bond. The electron acceptor organic compound is polyethylene terephthalate.

[0007] Based on the above technical solution, the present invention can also be improved as follows: Further, the mass ratio of the electron donor organic compound to the electron acceptor organic compound in Step 1 is: 0.001~0.05:1.

[0008] Further, the mass of the organic solvent is 2~3 times the sum of the masses of the electron donor organic compound and the electron acceptor organic compound.

[0009] Further, the organic solvent is ethanol.

[0010] Further, in Step 2, the mixed powder is heated to a transparent molten state at 270~290°C and maintained for 5~10 min.

[0011] Another objective of the present invention is to provide a polymer with thermally enhanced long persistent phosphorescent properties prepared according to one of the above objectives.

[0012] Another objective of the present invention is to provide a use of the polymer with thermally enhanced long persistent phosphorescent properties in the second objective in temperature-responsive optical sensors, multimodal dynamic anti-counterfeiting labels, and flexible optoelectronic memories.

[0013] The present invention has the following beneficial effects: 1. The polymer with thermally enhanced long afterglow properties in the present invention can generate long afterglow emissions with peaks at 520 nm (green light) or 560 nm (yellow-green light) respectively after being excited by 365 nm ultraviolet light. Its afterglow duration at room temperature reaches 12 hours, showing a significant improvement compared with the afterglow times of traditional phosphorescent materials in milliseconds and seconds. In addition, the polymer in the present invention exhibits a significant thermally activated afterglow enhancement effect in the temperature range of 20 - 200 °C, and the highest luminescence intensity can reach 56 times the initial value. Moreover, after the long afterglow of the polymer in the present invention completely decays, thermoluminescence can be generated through thermal stimulation.

[0014] In addition, the polymer in the present invention also has excellent chemical stability and solution processability. This polymer is applicable to technical fields such as temperature sensing, optical information encryption, and anti-counterfeiting. In particular, it can be processed into various shapes by 3D printing technology, which is convenient for combining with industrial components. When it is used in the field of temperature sensing, when the local temperature changes, the polymer will generate obvious thermoluminescence, efficiently reflecting the temperature change, thus realizing the temperature sensing function.

[0015] 2. In the present invention, the increase in long afterglow intensity during heating is mainly achieved through the following aspects: 1) By molecular engineering to regulate the orbital energy level and steric hindrance of the acceptor unit, a D - A type long afterglow system with thermal response characteristics is constructed; 2) Utilize the topological entanglement effect of the polymer matrix to inhibit the non - radiative inactivation of excitons, realizing an ultra - long afterglow of 12 - hour level at room temperature; 3) Adopt a planar locking strategy, that is, lock the benzene ring connected to the pinacol borate group and other benzene rings through carbon - carbon single bonds to avoid the rotation of the benzene ring under ultraviolet light irradiation, avoid ineffective energy loss, and also avoid the destruction of the overall configuration of the polymer, thereby avoiding fluorescence quenching, and finally breaking through the limitation of the thermal quenching effect of traditional organic materials. Description of the Drawings

[0016] Figure 1 It is the luminescence principle diagram of the polymer; Figure 2 It is the spectrogram of polymer BTPA@PET; Figure 3 It is the spectrogram of polymer BPCz@PET; Figure 4 It is the spectrogram of polymer BICz@PET; Figure 5 It is the long afterglow lifetime diagram of polymer BTPA@PET, polymer BPCz@PET, and polymer BICz@PET; Figure 6 It is the long afterglow lifetime diagram of polymer BTPA@PET at different temperatures; Figure 7Long afterglow lifetime diagram of polymer BPCz@PET at different temperatures; Figure 8 Long afterglow lifetime diagram of polymer BICz@PET at different temperatures; Figure 9 Long afterglow lifetime diagram of polymer BICz@PET under different light sources; Figure 10 Long afterglow lifetime diagram of polymer BICz@PET after heating treatment for 100 seconds of testing; Figure 11 Thermoluminescence spectra diagram of polymer BTPA@PET, polymer BPCz@PET and polymer BICz@PET; Figure 12 Absorption spectra diagram of polymer BTPA@PET before and after irradiation under 365 nm ultraviolet light; Figure 13 Absorption spectra diagram of polymer BPCz@PET before and after irradiation under 365 nm ultraviolet light; Figure 14 Absorption spectra diagram of polymer BICz@PET before and after irradiation under 365 nm ultraviolet light; Figure 15 Flow chart of polymer extrusion molding; Figure 16 Thermally enhanced long afterglow photograph diagram of the square structure prepared in Example 1 and the honeycomb structure prepared in Example 2, where Figure 16 Figure ① in is the thermally enhanced long afterglow photograph diagram of the honeycomb structure prepared in Example 2, Figure 16 Figure ② in is the thermally enhanced long afterglow photograph diagram of the square structure prepared in Example 1; Figure 17 Test result diagram of the thermal monitoring device simulated by the composite of the honeycomb structure made of polymer BICz@PET and the aluminum sheet in the real scene. Detailed implementation manners

[0017] Next, a polymer with thermally enhanced long afterglow characteristics, its preparation method and application in the present application will be described in combination with examples. However, the present application can be exemplified in many different forms and should not be construed as limited to the specific examples set forth herein. Rather, the purpose of providing these examples is to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0018] According to the inventor's aforementioned research, due to the problem of poor thermal stability of organic long afterglow materials, in the prior art, Yusheng Zhou et al. in the paper "Sunlight-Activated Hour-Long Afterglow from Transparent and Flexible Polymers" improved the stability of polymers by introducing benzene rings. However, the long afterglow luminescence intensity of the polymers prepared by them gradually decreases with the increase of temperature, showing the phenomenon of thermal quenching at high temperatures, which further limits the application of organic long afterglow materials.

[0019] Based on this, the present invention provides a polymer whose long afterglow intensity can increase when the temperature rises.

[0020] An embodiment of the first aspect of the present invention provides a method for preparing a polymer with thermally enhanced long afterglow characteristics, including the following steps: Step 1: Grind an electron donor organic compound and an electron acceptor organic compound together with an organic solvent to obtain a mixed powder; Step 2: Heat the mixed powder to a transparent molten state and then immediately cool it to room temperature to obtain a polymer with thermally enhanced long afterglow characteristics; The electron donor organic compound includes a triphenylamine group and a pinacol borate group connected to the triphenylamine group. Among them, the benzene ring in the triphenylamine group connected to the pinacol borate group is connected to at least one benzene ring in the remaining benzene rings in the triphenylamine group through a carbon-carbon single bond; The electron acceptor organic compound is polyethylene terephthalate (PET).

[0021] The luminescence mechanism of the polymer in the present invention is as Figure 1 shown. Specifically, after the polymer is irradiated with light, the electrons of the electron donor organic compound are captured by the molecules of the electron acceptor organic compound and move between the acceptor molecules, and finally return to the donor molecules to generate long afterglow luminescence.

[0022] The reasons for the enhancement of the afterglow intensity of the polymer in the present invention when the temperature rises are as follows: ① Ultraviolet excitation induces intramolecular charge transfer (ICT) of the electron donor organic compound (hereinafter referred to as donor unit A) to the lowest unoccupied molecular orbital (LUMO); ② By molecular engineering, the orbital energy level and steric hindrance of the electron acceptor organic compound (referred to as acceptor unit) are regulated to construct a D-A type long afterglow system with thermal response characteristics. At the D-A interface orbital coupling, electrons are directionally migrated from A-LUMO to PET matrix LUMO to form an exciplex excited state; ③ The exciplex dissociates to generate a radical anion (PET ·- ) and a cation (A ·+ , derived from the electron donor organic compound), and are spatially separated through the polymer chain; PET carrying excess electrons·- *Exchanging charges with A, resulting in a large amount of A being generated ·- *; ④ Under external thermal perturbation, A ·- *Performs the opposite charge exchange with PET, thereby generating PET ·- *Finally, PET ·- *and A ·+ *and A combine to release energy to produce long afterglow. Based on this, the temperature rise of the polymer in the present invention can accelerate the migration and recombination efficiency of charge carriers, thereby achieving an exponential enhancement of the afterglow intensity. It can be seen that the polymer in the present invention realizes the enhancement of the long afterglow intensity of the polymer during heating based on the synergistic effect of multi-stage energy transfer and thermal activation.

[0023] In addition, the electron donor organic compound in the present invention includes two parts: a triphenylamine group and a pinacol borate group. Triphenylamine has excellent electron-donating properties, and the further introduced pinacol borate group can effectively adjust the overall electron-donating ability of the molecule; in addition, in the present invention, the benzene ring connected to the pinacol borate group in the triphenylamine group is connected to at least one of the remaining benzene rings in the triphenylamine group through a carbon-carbon single bond, realizing the locking of the benzene ring and avoiding the rotation of the benzene ring under ultraviolet light irradiation (the reason is that the strong covalent bond interaction can effectively offset the rotation of the benzene ring), avoiding the destruction of the overall structure of the electron donor organic compound, thereby also avoiding ineffective energy loss, and finally realizing the enhancement of the long afterglow intensity of the polymer during heating.

[0024] Preferably, the structural formula of the electron donor organic compound in the present invention is: (Named: 4-(diphenylamino)phenylboronic acid pinacol ester (BICz), chemical formula: C 24 H 26 BNO2) or (Named: 9-phenyl-9H-carbazole-3-boronic acid pinacol ester (BPCz), chemical formula: C 24 H 24 BNO2), of course, in practice, it may also be other compounds similar in structure to the electron donor organic compound described in the present invention.

[0025] In some embodiments, the mass ratio of the electron donor organic compound to the electron acceptor organic compound in step 1 is: 0.001~0.05:1. In this embodiment, this mass ratio ensures that the prepared polymer has excellent long afterglow performance, thereby avoiding the long afterglow performance being poor due to too low a concentration of the electron donor organic compound when the mass ratio is less than 0.001:1; and also avoiding the long afterglow performance being poor due to concentration quenching when the mass ratio is greater than 0.05:1 because of too high a concentration of the electron donor organic compound.

[0026] In some embodiments, the mass of the organic solvent is 2 to 3 times the sum of the masses of the electron donor organic compound and the electron acceptor organic compound. This ratio can ensure that the electron donor organic compound and the electron acceptor organic compound are fully and evenly mixed. Preferably, the organic compound in this example can be ethanol, which has a low boiling point and is easily volatilized rapidly during the heating of the mixed powder, and does not participate in the reaction.

[0027] In addition, in some embodiments, the mixed powder in step 2 is heated to a transparent molten state at 270 - 290 °C and maintained for 5 - 10 minutes. This temperature range will not cause damage to the PET structure, and at the same time, this temperature range is also close to the melting point of PET, which is beneficial to obtaining a polymer with thermally enhanced long afterglow properties.

[0028] An embodiment of the second aspect of the present invention provides a polymer with thermally enhanced long afterglow properties, which is obtained by the method described in the embodiments of the first aspect.

[0029] An embodiment of the third aspect of the present invention provides an application of a polymer with thermally enhanced long afterglow properties. The polymer described in the embodiments of the second aspect is mainly used in technical fields such as temperature-responsive optical sensor devices, multimodal dynamic anti-counterfeiting labels, and flexible optoelectronic memories.

[0030] Examples The technical solutions in the present invention will be further explained and illustrated through specific examples as follows: Example 1 A preparation method of a polymer with thermally enhanced long afterglow properties, comprising the following steps: Step 1: Weigh 0.004 grams of BPCz (purity 99.9%) and 0.8 grams of PET (purity 99.9%); then add 3 milliliters of ethanol and grind thoroughly with an agate mortar for 0.5 hour to obtain a mixed powder; Step 2: Place the mixed powder into a quartz mold, and then place the quartz mold on a heating table at a temperature of 280 °C and heat for 5 minutes until the mixed powder is completely melted and becomes a transparent flowing state. Remove the quartz mold and quickly cool it to room temperature, and demold to obtain the polymer BPCz@PET with thermally enhanced long afterglow properties.

[0031] In addition, according to Figure 15 The flow chart of polymer extrusion molding, the polymer BICz@PET prepared in this example is made into a square structure by 3D printing.

[0032] Example 2 A preparation method of a polymer with thermally enhanced long afterglow properties, comprising the following steps: Step 1: Weigh 0.004 grams of BICz (purity 99.9%) and 0.8 grams of PET (purity 99.9%); then add 3 milliliters of ethanol and grind thoroughly with an agate mortar for 0.5 hours to obtain a mixed powder. Step 2: Place the mixed powder into a quartz mold, then place the quartz mold on a heating table at 280 °C and heat for 10 minutes until the powder completely melts into a transparent flowing state. Remove the quartz mold and quickly cool it to room temperature, and demold to obtain the polymer BICz@PET with thermally enhanced long afterglow properties.

[0033] In addition, according to Figure 15 the flow chart of polymer extrusion molding, the polymer BICz@PET prepared in this example is made into a honeycomb grid structure by 3D printing.

[0034] Comparative Example 1 A method for preparing a polymer, comprising the following steps: Step 1: Weigh 0.004 grams of BTPA (purity 99.9%) and 0.8 grams of PET (purity 99.9%); then add 3 milliliters of ethanol and grind thoroughly with an agate mortar for 0.5 hours to obtain a mixed powder; wherein, the structural formula of BTPA is: .

[0035] Step 2: Place the mixed powder into a quartz mold, then place the quartz mold on a heating table at 280 °C and heat for 10 minutes until the powder completely melts into a transparent flowing state. Remove the quartz mold and quickly cool it to room temperature, and demold to obtain the polymer BTPA@PET with thermally enhanced long afterglow properties.

[0036] Test analysis: 1. Conduct emission spectrum, phosphorescence spectrum, and long afterglow spectrum test analysis on the polymers prepared in Comparative Example 1, Example 1, and Example 2. The test results are shown in detail in Figure 2 , Figure 3 and Figure 4 ; among them, Figure 2 is the spectrogram of the polymer BTPA@PET; Figure 3 is the spectrogram of the polymer BPCz@PET; Figure 4 is the spectrogram of the polymer BICz@PET; among them, Figure 2 , Figure 3 and Figure 4 the PL in are the emission spectrum curves, the RTP are the phosphorescence spectrum curves, and the LPL are the long afterglow spectrum curves.

[0037] From Figure 2It can be seen that the fluorescence emission peak of the polymer prepared in Comparative Example 1 is at 520 nm (green light), the phosphorescence emission peak is at 520 nm (green light), and the long afterglow emission peak is at 520 nm (green light); from Figure 3 It can be seen that the fluorescence emission peak of the polymer prepared in Example 1 is at 470 nm (blue-green light), the phosphorescence emission peak is at 520 nm (green light), and the long afterglow emission peak is at 520 nm (green light); from Figure 4 It can be seen that the fluorescence emission peak of the polymer prepared in Example 2 is at 380 nm (blue light), the phosphorescence emission peak is at 480 nm (blue-green light), and the long afterglow emission peak is at 560 nm (yellow-green light).

[0038] 2. Measurement of the long afterglow lifetime of the polymer (1)Measurement of the long afterglow lifetime of the polymer after light irradiation The results of the long afterglow lifetime measurement of the polymers prepared in Comparative Example 1, Example 1 and Example 2 after being irradiated with 60W 365 nm ultraviolet light for 3 minutes are as Figure 5 shown, Figure 5 which are the long afterglow lifetime diagrams of the polymers BTPA@PET, BPCz@PET and BICz@PET.

[0039] From Figure 5 it can be seen that the long afterglow lifetime of the polymer BTPA@PET prepared in Comparative Example 1 can exceed 10 4 seconds; the long afterglow lifetime of the polymer BPCz@PET prepared in Example 1 can exceed 10 4 seconds; the long afterglow lifetime of the polymer BICz@PET prepared in Example 2 can exceed 10 4 seconds.

[0040] (2)Measurement of the long afterglow lifetime of the polymer at different temperatures The polymers prepared in Comparative 1, Example 1 and Example 2 were placed in different temperature environments (wherein, the polymers prepared in Comparative Example 1 and Example 1 were tested in environments of 300K and 380K, and the polymer prepared in Example 2 was tested in environments of 300K, 325K, 350K, 375K and 400K) to measure the afterglow lifetime of the polymer. The test results are respectively as Figure 6 , Figure 7 and Figure 8 shown, where Figure 6 is the long afterglow lifetime diagram of the polymer BTPA@PET at different temperatures, Figure 7 is the long afterglow lifetime diagram of the polymer BPCz@PET at different temperatures, Figure 8 is the afterglow lifetime diagram of the polymer BICz@PET at different temperatures.

[0041] From Figure 6 It can be seen that for the polymer BTPA@PET prepared in Comparative Example 1, as the ambient temperature increases, the initial afterglow intensity decreases, the afterglow lifetime shortens, and the afterglow performance deteriorates with increasing temperature. From Figure 7 It can be seen that for the polymer BPCz@PET prepared in Example 1, as the ambient temperature increases, the initial afterglow intensity increases and the afterglow lifetime shortens. From Figure 8 It can be seen from [the figure] that for the polymer BICz@PET prepared in Example 2, as the ambient temperature increases, the initial afterglow intensity also increases and the afterglow lifetime shortens.

[0042] (3)Afterglow lifetime test of polymers irradiated with different light sources The polymer BICz@PET prepared in Example 2 was irradiated with different light sources (365 nm ultraviolet light, natural light, 393 nm ultraviolet light, 254 m ultraviolet light) for 3 minutes, and then the afterglow lifetime of the polymer was tested. The test results are as Figure 9 shown; Figure 9 is the long afterglow lifetime diagram of the polymer BICz@PET under different light sources.

[0043] From Figure 9 it can be seen that after being irradiated with 365 nm ultraviolet light for 3 minutes, the polymer BICz@PET exhibits the longest long afterglow lifetime.

[0044] 3. After the polymer BICz@PET prepared in Example 2 was tested for 100 seconds, it was heat-treated, and the heating temperatures during the test were: 325 K, 350 K, 375 K, and 400 K. The test results are shown in detail in Figure 10 .

[0045] Figure 10 is the long afterglow lifetime diagram of the polymer BICz@PET after being heat-treated after 100 seconds of testing; from Figure 10 it can be seen that for the polymer BICz@PET, as the temperature increases, the afterglow intensity increases.

[0046] 4. Thermal-optical spectroscopy analysis of polymers The polymer BTPA@PET prepared in Comparative Example 1, the polymer BPCz@PET prepared in Example 1, and the polymer BICz@PET prepared in Example 2 were placed in an aluminum cell with a volume of 8 cubic millimeters, and thermoluminescence spectroscopy analysis was carried out under a high voltage of 1000 volts for the PMT (photomultiplier tube) and a heating rate of 3 °C / s. The test results are as Figure 11 shown.

[0047] Figure 11 are the thermoluminescence spectroscopy diagrams of the polymer BTPA@PET, the polymer BPCz@PET, and the polymer BICz@PET. FromFigure 11 It can be seen that the thermoluminescence peak of polymer BTPA@PET is mainly at 425 K, belonging to the category of deep traps. The thermoluminescence intensity of the BTPA@PET film is the lowest among the three, resulting in the difficulty of effectively replenishing thermoluminescence under high temperature, and the overall performance shows a decline in afterglow performance. The thermoluminescence peak of polymer BPCz@PET is mainly at 415 K, belonging to the category of deep traps. The thermoluminescence intensity of the BPCz@PET film is very high, indicating that it has a high trap concentration, resulting in the ability of its thermoluminescence under high temperature to effectively replenish thermoluminescence quenching, and the overall performance shows an improvement in afterglow performance; the thermoluminescence peak of polymer BICz@PET is mainly at 435 K, belonging to the category of deep traps, and at the same time the signal intensity is the highest among the three, which is consistent with the law of long afterglow life. The thermoluminescence intensity of the BICz@PET film is the highest among the three, with the highest trap concentration, resulting in the ability of its thermoluminescence under high temperature to effectively replenish thermoluminescence quenching, and the overall performance shows an improvement in afterglow performance.

[0048] 5. Polymer Absorption Spectrum Analysis The polymer BTPA@PET prepared in Comparative Example 1, the polymer BPCz@PET prepared in Example 1, and the polymer BICz@PET prepared in Example 2 were irradiated under a 365 nm ultraviolet lamp with a power of 60 W for 3 minutes and then subjected to absorption spectrum analysis. The test results are shown in Figure 12 , Figure 13 and Figure 14 respectively.

[0049] Among them, Figure 12 is the absorption spectrum diagram of polymer BTPA@PET before and after irradiation under a 365 nm ultraviolet lamp; Figure 13 is the absorption spectrum diagram of polymer BPCz@PET before and after irradiation under a 365 nm ultraviolet lamp; Figure 14 is the absorption spectrum diagram of polymer BICz@PET before and after irradiation under a 365 nm ultraviolet lamp.

[0050] From Figure 12 it can be seen that after being irradiated by light, the absorption spectrum of polymer BTPA@PET produces an obvious absorption band at 500 - 800 nm, and the new absorption band is attributed to the generation of BTPA ·+ and PET ·- free radicals. From Figure 13 it can be seen that after being irradiated by light, the absorption spectrum of polymer BPCz@PET produces an obvious absorption band at 500 - 800 nm, and the new absorption band is attributed to the generation of BPCz ·+ and PET ·- free radicals. From Figure 14It can be seen that after being irradiated by light, the absorption spectrum of the polymer BICz@PET produces an obvious absorption band at 500 - 800 nm, and the new absorption band is attributed to BICz ·+ and PET ·- the generation of free radicals.

[0051] 6. The long afterglow test of the square structure made of the polymer BPCz@PET by 3D printing and the honeycomb structure made of the polymer BICz@PET by 3D printing. During the test, the square structure and the honeycomb structure were heated by a heating plate, and the long afterglow intensity at different temperatures was observed. The test results are as Figure 16 shown.

[0052] Figure 16 Figure 13 is the photo of the thermally enhanced long afterglow of the square structure prepared in Example 1 and the honeycomb structure prepared in Example 2. Among them, Figure 16 Figure ① in it is the photo of the thermally enhanced long afterglow of the honeycomb structure prepared in Example 2, Figure 16 and Figure ② in it is the photo of the thermally enhanced long afterglow of the square structure prepared in Example 1. It can be seen from Figure 16 Figure ① in it that as the temperature rises, the intensity of the yellow - green long afterglow of the honeycomb structure formed by 3D printing of the polymer BICz@PET gradually increases when heating the heating plate; it can be seen from Figure 16 Figure ② in it that as the temperature rises, the intensity of the green long afterglow of the square structure formed by 3D printing of the polymer BPCz@PET gradually increases when heating the heating plate.

[0053] 7. The long afterglow test of the honeycomb grid structure made of the polymer BICz@PET by 3D printing in Example 2. During the test, the honeycomb grid structure was wrapped on an aluminum cylinder to form a simple thermal monitoring device. During the test, the aluminum cylinder was heated, and the test results are as Figure 17 shown.

[0054] Figure 17 Figure 30 is the test result diagram of the thermal monitoring device simulating the real - world scenario by the composite of the honeycomb structure made of the polymer BICz@PET and the aluminum sheet. It can be seen from Figure 17 it that the corresponding position of the polymer cylinder outside the aluminum cylinder shows an enhanced yellow - green long afterglow, effectively reflecting the change and distribution of temperature.

[0055] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a polymer with thermally enhanced long afterglow properties, characterized in that, It includes the following steps: Step 1: Grind an electron donor organic substance, an electron acceptor organic substance and an organic solvent together to obtain a mixed powder material; Step 2: Heat the mixed powder material to a transparent molten state and then immediately cool it to room temperature to obtain a polymer with thermally enhanced long afterglow properties; The electron donor organic substance includes a triphenylamine group, a pinacol borate group connected to the triphenylamine group, and the benzene ring in the triphenylamine group connected to the pinacol borate group is connected to at least one benzene ring in the remaining benzene rings in the triphenylamine group through a carbon-carbon single bond; The electron acceptor organic substance is polyethylene terephthalate.

2. The preparation method according to claim 1, wherein In Step 1, the mass ratio of the electron donor organic substance to the electron acceptor organic substance is 0.001 - 0.05:

1.

3. The preparation method according to claim 1, wherein The mass of the organic solvent is 2 - 3 times the sum of the masses of the electron donor organic substance and the electron acceptor organic substance.

4. The preparation method according to claim 3, wherein, The organic solvent is ethanol.

5. The preparation method according to claim 1, characterized in that In Step 2, the mixed powder material is heated to a transparent molten state at 270 - 290 °C and maintained for 5 - 10 min.

6. A polymer with thermally enhanced long afterglow properties prepared by the preparation method according to any one of claims 1 - 5.

7. Application of the polymer with thermally enhanced long afterglow properties in claim 6 in a temperature-responsive optical sensor, a multimodal dynamic anti-counterfeiting label and a flexible optoelectronic memory.

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