Dynamic response type polymer with aggregation-induced emission characteristic as well as preparation method and application of dynamic response type polymer

Abstract

The invention relates to the technical field of polymer synthesis, in particular to a dynamic response type polymer with aggregation-induced emission characteristics and a preparation method and application thereof. The dynamic response type polymer is formed by polymerizing raw materials including a compound containing a diphenylmethane structure and a derivative thereof and a sulfur-containing side chain or a directly connected sulfur-containing group compound. The dynamic response type polymer disclosed by the invention realizes a dynamic luminescence process, and solves the problems that the original AIE polymer is simple in luminescence process, low in information encryption degree and unobvious in environmental response signal; the total visible light emission can be conveniently and accurately adjusted by changing the electron supply and absorption capacity of the core group structure, the real-time emission adjustment capacity of the same material is achieved, industrial-grade raw materials and a mature synthesis process are adopted, the cost is low, synthesis is convenient, and the 4D dynamic anti-counterfeiting encryption material has wide application prospects in the field of 4D dynamic anti-counterfeiting encryption.

Description

Technical Field

[0001] This invention relates to the field of polymer synthesis technology, and in particular to a dynamically responsive polymer with aggregation-induced emission properties, its preparation method, and its applications. Background Technology

[0002] Aggregation-induced emission (AIE) materials are a novel fluorescent material system. AIE is a fluorescence phenomenon distinct from traditional luminescence; therefore, AIE materials exhibit properties unique to traditional fluorescent materials, significantly improving the sensitivity, specificity, and resolution of biological detection and fluorescence imaging.

[0003] In the field of AIE materials, existing technologies mainly achieve AIE functionalization through the following methods: (1) Covalent fixation of AIE groups: AIE groups (such as tetraphenylethylene derivatives) are covalently attached to the polymer backbone or side chain, as described in patents with publication numbers CN111333812A and CN119118889A. This method requires multi-step synthesis and purification processes, and the synthesis process is complex and costly.

[0004] (2) Using additional chromophores or metal catalysts: The AIE effect can be induced by introducing additional chromophores or metal catalysts (such as platinum complexes), as described in patents with publication numbers CN112898962A and CN110628039A. This method requires the use of precious metal materials, which increases costs, and may require special synthesis conditions.

[0005] (3) Supramolecular interaction: AIE effect is generated by utilizing supramolecular interactions such as hydrogen bonds. However, the emission wavelength of this method is limited, and it is difficult to achieve emission wavelength adjustment in the entire visible light range, as described in the literature Y. Yao, Z. Xu, B. Liu, M. Xiao, J. Yang, W. Liu, Adv. Funct. Mater. 2021, 31(4), 2006944. However, the emission wavelength adjustment capability of this method is limited.

[0006] (4) Physical blending method: AIE molecules are added through physical blending. However, this method has problems such as poor mechanical properties (tensile strength less than 10 MPa) and fluorescence quenching, as described in patent publication number CN110592711A, but the application of this method is limited.

[0007] In summary, the existing AIE functionalization methods have the following problems: (1) High cost: The raw materials of traditional AIE polymers are expensive, such as tetraphenylethylene derivatives which cost about RMB 3,500 / kg and require further structural modification before use. In addition, the use of precious metal catalysts also increases the cost. (2) Complex synthesis: Catalysts need to be introduced or multi-step synthesis is required, such as protection-deprotection reactions, which increases the difficulty and cost of synthesis. It is difficult to achieve in-situ functionalization by relying on pre-synthesized AIE molecules. (3) Limited application: Existing fluorescent materials cannot use mature resin raw materials for industrial-grade in-situ AIE functionalization. The application is mainly concentrated in the mid-to-high-end fields and it is difficult to widely apply to large-scale industrial production. (4) Simple luminescence process: The luminescence process of traditional AIE polymers is relatively simple, lacks dynamic adjustment capability, has low information encryption level, and the environmental response signal is not obvious. (5) Difficulty in adjusting emission wavelength: The adjustment of emission wavelength of traditional AIE polymers usually requires replacing AIE emission units, which involves complex synthesis steps and expensive raw materials. The adjustment method is simple, and the emission wavelength of the same chromophore is fixed. Summary of the Invention

[0008] This invention provides a dynamically responsive polymer with aggregation-induced emission properties, its preparation method, and its application, in order to solve the problems of high cost, complex synthesis, limited application, simple emission process, and difficulty in adjusting emission wavelength in existing AIE functionalization methods.

[0009] According to a first aspect of the present invention, the present invention provides a dynamically responsive polymer with aggregation-induced emission properties, which is polymerized from raw materials comprising compounds containing diphenylmethane structures and their derivatives and compounds containing sulfur-containing side chains or directly connected sulfur-containing groups.

[0010] Furthermore, the compound containing sulfur-containing side chains or directly connected sulfur-containing groups contains one or more of methylthio, ethylthio, and mercapto groups.

[0011] Furthermore, the compounds containing diphenylmethane structures and their derivatives include one or more of 4,4'-diaminodiphenylmethane, diphenylmethane diisocyanate, 2,2'-methylenediphenol, N,N,N,N'-tetraglycidyl-4,4-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(2-ethyl)aniline, 4,4'-bismaleimide diphenylmethane, and 4,4'-methylenebis[N-sec-butylaniline] and bis(4-hydroxyphenyl)aniline.

[0012] Further, the compound containing a sulfur-containing side chain or a directly linked sulfur-containing group includes one or more of dimethylthiotoluene diamine, pentaerythritol tetra(3-mercaptopropionate), 3-aminobenzylthiophenol, diaminobenzylthiophenol, 4-aminobutane-1-thiol, 4-hydroxybenzylthiol, 4,6-dihydroxy-2-methylthiopyrimidine, 4-(methylthio)phenyl-1,2-diamine, 3,6-dioxa-1,8-octanedithiol, dimercaptoethanol, and 2-(methylthio)-5-aminopyrimidine.

[0013] Furthermore, the molar ratio of the compound containing the diphenylmethane structure and its derivatives to the compound containing the sulfur-containing side chain or directly connected sulfur-containing group is less than 10:1.

[0014] Furthermore, the raw materials for preparation also include polymer matrix materials with aromatic structures; Preferably, the molar ratio of the polymer matrix material to the compound containing sulfur-containing side chains or directly connected sulfur-containing groups is (1-3):1; Preferably, the polymer matrix material is a compound containing epoxy functional groups.

[0015] Furthermore, the raw materials for preparation also include polyether polyols or polyester polyols, wherein the molar ratio of the compound containing the diphenylmethane structure and its derivatives to the polyether polyol or polyester polyol is (3-8):1.

[0016] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-described dynamic responsive polymer, wherein a compound containing a diphenylmethane structure and its derivatives and a compound containing sulfur-containing side chains or directly connected sulfur-containing groups are polymerized under conditions in the absence of free radical scavengers and free radical terminators.

[0017] Furthermore, the polymerization reaction is a random copolymerization reaction, a block copolymerization reaction, or an alternating copolymerization reaction; Preferably, the polymerization reaction is carried out under conditions of a photoinitiator and / or a crosslinking agent; More preferably, the photoinitiator is selected from one or more of benzoin dimethyl ether, 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, and 2-isopropylthioxanthone; the crosslinking agent is selected from one or more of 3,6-dioxa-1,8-octanedithiol, pentaerythritol tetra-3-mercaptopropionate, and trimethylolpropane tris(3-mercaptopropionate).

[0018] According to a third aspect of the present invention, the present invention also provides the application of the above-described dynamic responsive polymer in 4D dynamic anti-counterfeiting encryption.

[0019] Preferably, the application method uses at least two different dynamic responsive polymers to perform 4D dynamic anti-counterfeiting encryption under light irradiation; more preferably, the at least two different dynamic responsive polymers satisfy different emission rates and / or emission wavelengths.

[0020] The beneficial effects of this invention are: This invention provides a dynamically responsive polymer with aggregation-induced emission (AIE) properties. Compared with traditional AIE functionalization methods, it achieves a dynamic emission process, solving the problems of simple emission processes, low information encryption, and unclear environmental response signals in traditional AIE polymers. By changing the electron-donating and electron-withdrawing capabilities of the core group structure, it can conveniently and precisely adjust the emission of all visible light and has the ability to adjust the emission in real time with the same material, solving the problems of difficult wavelength adjustment, single adjustment method, and fixed emission wavelength of the same colorimetric unit in traditional AIE polymers. It uses industrial-grade raw materials and mature synthesis processes, resulting in low cost and convenient synthesis, solving the problems of high cost and complex synthesis in existing AIE functionalization methods. It realizes in-situ AIE functionalization of industrial resins, solving the application limitations of existing fluorescent materials that cannot use mature resin raw materials for industrial-grade in-situ AIE functionalization. It has broad application prospects in the field of 4D dynamic anti-counterfeiting encryption. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This diagram illustrates the reaction process of the dynamically responsive polymer of the present invention forming a fluorescent intermediate structure under light irradiation.

[0023] Figure 2 This diagram illustrates the characteristic fluorescence luminescence behavior of the dynamically responsive polymer of this invention.

[0024] Figure 3 This is a graph showing the luminescence behavior of the dynamically responsive polymer provided in Embodiment 1 of the present invention.

[0025] Figure 4 The structure characterization diagram of the dynamically responsive polymer provided in Example 1 of the present invention is shown in the figure; wherein, (a) is a steady-state fluorescence emission spectrum; (b) is a UV-Vis diffuse reflectance spectrum before, during and after excitation; and (c) is a Raman spectrum before, during and after excitation.

[0026] Figure 5 This is a graph showing the luminescence behavior of the dynamically responsive polymer provided in Embodiment 2 of the present invention.

[0027] Figure 6 The fluorescence emission spectrum and structural characterization of the dynamic responsive polymer provided in Example 2 of the present invention are shown in the figures. (a) is the UV-Vis diffuse reflectance spectrum before, during and after excitation; (b) is the Raman spectrum before, during and after excitation; and (c) is the steady-state fluorescence excitation spectrum and emission spectrum.

[0028] Figure 7 The image shows the in-situ XPS sulfur fine spectrum of the dynamic response polymer provided in Example 2 of this invention; where (a) is before excitation; (b) is during excitation; and (c) is after excitation.

[0029] Figure 8 The fluorescence emission spectrum of the dynamically responsive polymer provided in Example 3 of the present invention is shown.

[0030] Figure 9 This is a graph showing the luminescence behavior of the dynamically responsive polymer provided in Example 4 of the present invention.

[0031] Figure 10 This is a graph showing the luminescence behavior of the dynamically responsive polymer provided in Example 5 of the present invention.

[0032] Figure 11 This is a schematic diagram of the basic dynamic luminescence behavior of the fluorescent material of the dynamically responsive polymer provided in Embodiment 7 of the present invention.

[0033] Figure 12 This is a schematic diagram illustrating the differences in the luminescence behavior of the dynamically responsive polymer provided in Embodiment 7 of the present invention.

[0034] Figure 13 This is one of the schematic diagrams illustrating the decryption process of the dynamically responsive polymer applied in 4D dynamic anti-counterfeiting encryption according to Embodiment 7 of the present invention.

[0035] Figure 14 This is a schematic diagram of the luminescence behavior of the dynamically responsive polymer PU3 provided in Embodiment 7 of the present invention.

[0036] Figure 15 This is the second schematic diagram of the decryption process of the dynamic responsive polymer applied in 4D dynamic anti-counterfeiting encryption according to Embodiment 7 of the present invention.

[0037] Figure 16 This is the third schematic diagram of the decryption process of the dynamic responsive polymer applied in 4D dynamic anti-counterfeiting encryption according to Embodiment 7 of the present invention.

[0038] Figure 17 This is a schematic diagram of the basic dynamic luminescence behavior of the dynamically responsive polymer E1 provided in Embodiment 8 of the present invention.

[0039] Figure 18This is a schematic diagram illustrating the decryption process of the dynamically responsive polymer applied in 4D dynamic anti-counterfeiting encryption, as provided in Embodiment 8 of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] In a first typical embodiment of the present invention, the present invention provides a dynamically responsive polymer with aggregation-induced emission properties, which is polymerized from raw materials including compounds containing diphenylmethane structures and their derivatives and compounds containing sulfur-containing side chains or directly connected sulfur-containing groups.

[0042] Static luminescence refers to the process of directly and stably emitting light when exposed to ultraviolet light, while dynamic luminescence refers to the gradual change in the AIE emission behavior of a material when exposed to ultraviolet light. This provides a new platform for realizing more complex information transmission and encryption processes, and solves the shortcomings of the original AIE polymer luminescence process, such as its simplicity, low degree of information encryption, and unclear environmental response signals. The dynamically responsive polymer of this invention possesses unique structural characteristics. When irradiated with a UV light source with a wavelength less than 405 nm, it generates a specific intermediate structure. This intermediate structure has reversible C=S bonds, which can excite free radical recombination under light and slowly decompose and break down in the dark. This overcomes the shortcomings of traditional AIE polymers, such as simple luminescence processes, low information encryption, and unclear environmental response signals. The two phenyl groups adjacent to the C=S bonds can synergistically interact with the C=S bonds to precisely control the electron cloud density and emission capability of the AIE chromophores. By controlling the chemical reaction process, the formation structure of the AIE building blocks can be adjusted in real time, thereby achieving convenient, precise, real-time, and wide-range AIE emission wavelength adjustment. This solves the shortcomings of traditional AIE polymers, such as difficulty in adjusting the emission wavelength, limited adjustment methods, and fixed emission wavelengths for the same chromophore unit. The target core structure required for the polymer of this invention is widely present in industrial resin systems, such as MDI, MDA, DMTDA, and PETMP. Furthermore, this invention only requires two core structures to exist in the polymer to achieve the AIE function of the resin, without further targeted treatment, thus eliminating the need to modify the synthesis technology of mature resins.

[0043] According to some specific embodiments of the present invention, the reaction process of the dynamically responsive polymer of the present invention forming a fluorescent intermediate structure under light irradiation is as follows: Figure 1As shown, compounds containing diphenylmethane structures and their derivatives, as well as compounds with sulfur-containing side chains or directly connected sulfur-containing groups, will form C=S structures under light irradiation, thereby altering the molecular chain stacking structure and inducing the AIE effect. Furthermore, there exists a generalized reaction pattern: sulfur-containing side chains or directly connected sulfur-containing groups undergo homolytic cleavage under light irradiation, and the generated free radicals bond with benzyl free radicals similar to diphenylmethane to form C=S structures. The characteristic fluorescence luminescence behavior of the dynamically responsive polymers of this invention is as follows: Figure 2 As shown, the double bond structure decomposes spontaneously in the dark and regenerates under light, giving the polymer a unique photoluminescence process.

[0044] The raw material combination and polymerization method of the polymer of this invention can realize in-situ AIE functionalization of industrial resin. By using mature industrial-grade resin raw materials and synthesis methods, the resin can be endowed with AIE properties without additional complex processing. This solves the problem of mismatch between the original AIE building blocks and the existing large-scale industrial resin system, while reducing costs and improving the convenience of production.

[0045] Preferably, the compound containing sulfur-containing side chains or directly connected sulfur-containing groups contains one or more of methylthio, ethylthio, and mercapto groups.

[0046] According to some specific embodiments of the present invention, the compounds containing diphenylmethane structures and their derivatives include one or more of 4,4'-diaminodiphenylmethane, diphenylmethane diisocyanate, 2,2'-methylenediphenol, N,N,N,N'-tetraglycidyl-4,4-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(2-ethyl)aniline, 4,4'-bismaleimide diphenylmethane, and 4,4'-methylenebis[N-sec-butylaniline], bis(4-hydroxyphenyl)aniline. These compounds have wide industrial applications and mature synthesis technologies, are relatively inexpensive and readily available, thus ensuring effective control of polymer production costs, facilitating large-scale production and application, and further enhancing the competitiveness and practicality of the polymer in the industrial field.

[0047] According to some specific embodiments of the present invention, the compounds containing sulfur-containing side chains or directly linked sulfur-containing groups include one or more of dimethylthiotoluene diamine, pentaerythritol tetra(3-mercaptopropionate), 3-aminobenzylthiophenol, diaminobenzylthiophenol, 4-aminobutane-1-thiol, 4-hydroxybenzylthiol, 4,6-dihydroxy-2-methylthiopyrimidine, 4-(methylthio)phenyl-1,2-diamine, 3,6-dioxa-1,8-octanedithiol, dimercaptoethanol, and 2-(methylthio)-5-aminopyrimidine. These compounds also have good availability and low cost, and when polymerized with compounds containing diphenylmethane structures and their derivatives, they can better achieve the imparting and regulation of AIE properties, providing more options for polymer performance optimization, and also enriching the polymer synthesis raw material system, facilitating flexible adjustments according to different needs.

[0048] According to some specific embodiments of the present invention, the molar ratio of the compound containing the diphenylmethane structure and its derivatives to the compound containing the sulfur-containing side chain or directly connected sulfur-containing group is less than 10:1. A suitable molar ratio helps optimize the structure and properties of the polymer, ensuring sufficient interaction between the two key structures, thereby better achieving effects such as dynamic luminescence, emission wavelength modulation, and in-situ AIE functionalization of industrial resins, thus guaranteeing the polymer's advantages in performance and applications.

[0049] According to some specific embodiments of the present invention, the molar ratio of the compound containing the diphenylmethane structure and its derivatives to the compound containing the sulfur-containing side chain or directly connected sulfur-containing group is (1-3):1.

[0050] According to some specific embodiments of the present invention, the raw materials for preparation further include a polymer matrix material having an aromatic structure; preferably, the molar ratio of the polymer matrix material to the compound containing sulfur-containing side chains or directly connected sulfur-containing groups is (1-3):1.

[0051] The polymer matrix material can be epoxy resin, polyurethane, polyimide, polybenzimidazole and polyphenylene sulfide.

[0052] Preferably, the polymer matrix material is a compound containing epoxy functional groups. Examples include: bisphenol A type epoxy resins (E-51, E-44), bisphenol F type epoxy resins, methyl glycidyl propionate, phenyl glycidyl propionate, triglycidyl isocyanurate (TGIC), tetraglycidyl diaminodiphenylmethane (TGDDM), epoxidized polybutadiene, and vinyl epoxy compounds (such as ethylene oxide vinyl ether).

[0053] Polymer matrix materials contain a large number of aromatic structures. By adjusting the electron cloud density and conjugation degree of the matrix material, fluorescent polymers with longer wavelengths can be obtained.

[0054] According to some specific embodiments of the present invention, the raw materials for preparation also include polyether polyols or polyester polyols, such as: polypropylene glycol, polytetrahydrofuran glycol, polyethylene glycol, copolyether polyol, adipic acid polyester, phthalic acid polyester, polycaprolactone polyol, wherein the molecular weight of the soft segment monomer is selected in the range of 0 to 10000.

[0055] The molar ratio of the compound containing the diphenylmethane structure and its derivatives to the polyether polyol or polyester polyol is (3-8):1.

[0056] In a second typical embodiment of the present invention, the present invention also provides a method for preparing the above-mentioned dynamic responsive polymer, wherein a compound containing a diphenylmethane structure and its derivatives and a compound containing sulfur-containing side chains or directly connected sulfur-containing groups are polymerized under conditions in the absence of free radical scavengers and free radical terminators.

[0057] The dynamic responsive polymer of the present invention is prepared in the absence of free radical scavengers and free radical terminators. This ensures the smooth progress of the polymerization reaction and the integrity of the polymer structure, avoids the adverse effects of free radical scavengers and terminators on polymer performance, and is conducive to obtaining dynamic responsive polymers with excellent performance and stability. At the same time, it simplifies the preparation process and reduces production difficulty and cost.

[0058] According to some specific embodiments of the present invention, the polymerization reaction is a random copolymerization reaction, a block copolymerization reaction, or an alternating copolymerization reaction. Different copolymerization methods can endow the polymer with different microstructures and performance characteristics, thereby meeting different application requirements.

[0059] According to some specific embodiments of the present invention, the polymerization reaction is carried out under conditions of a photoinitiator and / or a crosslinking agent.

[0060] The use of photoinitiators and crosslinking agents can effectively regulate the rate and extent of polymerization reactions, improve the crosslinking density and mechanical properties of polymers, and further optimize the overall performance of polymers, making them more suitable for practical applications such as 4D dynamic anti-counterfeiting encryption. At the same time, it broadens the processing and application methods of this polymer.

[0061] Preferably, the photoinitiator is selected from one or more of benzoin dimethyl ether, 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, and 2-isopropylthioxanthone; the crosslinking agent is selected from one or more of 3,6-dioxa-1,8-octanedithiol, pentaerythritol tetra-3-mercaptopropionate, and trimethylolpropane tris(3-mercaptopropionate).

[0062] More preferably, the amount of the photoinitiator is 1-3% of the mass of the compound containing sulfur-containing side chains or directly connected sulfur-containing groups. The amount of the crosslinking agent is 10-20% of the mass of the compound containing sulfur-containing side chains or directly connected sulfur-containing groups.

[0063] According to some specific embodiments of the present invention, the polymerization reaction is carried out under catalytic conditions. Preferably, the catalyst includes triethylamine, dibutyltin dilaurate (DBTDL), etc.

[0064] In a third typical embodiment of the present invention, the present invention also provides the application of the above-mentioned dynamic responsive polymer in 4D dynamic anti-counterfeiting encryption.

[0065] Based on the unique dynamic luminescence characteristics and emission wavelength adjustment capability of the dynamic responsive polymer of this invention, controllable encryption can be achieved in multiple dimensions such as time, space, wavelength, and environment. Decryption only requires simple equipment such as ultraviolet lamps. Compared with traditional anti-counterfeiting materials, it has higher security and convenience, and solves the problems that the original information encryption is limited to one or two dimensions, as well as the high price and complex encryption of advanced anti-counterfeiting materials. It has broad application prospects and market value.

[0066] According to some specific embodiments of the present invention, the application method is as follows: Preferably, the application method uses at least two different dynamic responsive polymers to perform 4D dynamic anti-counterfeiting encryption under light irradiation (preferably ultraviolet irradiation); more preferably, the at least two different dynamic responsive polymers satisfy different emission rates and / or emission wavelengths; wherein, the different dynamic responsive polymers should satisfy the following differences: 1. Different emission rates: the two dynamic responsive AIE polymers will slowly emit light within a few seconds to tens of seconds under light irradiation, but depending on the specific formulation adjustment, the emission rates of the two polymers will show a difference of more than ten times, and correspondingly, the de-excitation rates of the two polymers will also show a difference of several times. The existence of this difference is the key to the 4D dynamic encryption and decryption technology. 2. Different emission wavelengths: the emission wavelengths of the two AIE polymers of the present invention will change with the extension of light irradiation time, but depending on the specific formulation adjustment, the change in wavelength will be significantly different. Therefore, the information generated by the two fluorescent polymers in terms of emission wavelength is significantly different, which can be used for information encryption.

[0067] In some specific embodiments, method one is applied: encryption based on the time dimension of "emission speed difference". (1) Encryption: Two polymers (e.g., PU1 and PU2) are used, one with a photoinitiator (e.g., PU2) and the other without (e.g., PU1). The two are processed into a mixed pattern, at which point the information is not visible.

[0068] (2) Decryption: After being irradiated with ultraviolet light for a period of time (e.g., 30 seconds), both polymers were excited to emit light.

[0069] After being kept in the dark for a period of time (e.g., 6-8 minutes): the polymer with added photoinitiator de-excites quickly due to the action of the photoinitiator (fluorescence disappears), while the polymer without added photoinitiator de-excites more slowly. At this time, a short exposure to light will reveal the encrypted information of the polymer without added photoinitiator.

[0070] In some specific embodiments, method two is applied: continuous exposure encryption based on "gradual change of illumination wavelength". (1) Encryption: Two polymers (e.g., PU1 and PU3) are used. The first, a dynamically responsive polymer (PU3), undergoes a gradual change in fluorescence wavelength from a first color (e.g., orange) to a second color (e.g., green) under prolonged ultraviolet irradiation, while the second, a dynamically responsive polymer (PU1), does not exhibit this change. When the two are mixed to form a pattern, the information is initially indistinguishable.

[0071] (2) Decryption: After continuous ultraviolet irradiation for a period of time (e.g., 30 minutes): the first dynamic responsive polymer gradually changes to the second color fluorescence, which contrasts with the first color fluorescence of the second dynamic responsive polymer, directly revealing the encrypted information.

[0072] In some specific embodiments, method three is applied: secondary excitation encryption based on "initial wavelength change after de-excitation": (1) Encryption: The first dynamic responsive polymer in the same application method (which will recover to the initial excited state of the second color after being exposed to light for a long time and left to stand in the dark for 1 hour) is mixed with the second dynamic responsive polymer to form a pattern.

[0073] (2) Decryption: Initial irradiation for a period of time (e.g., 30 minutes): The wavelength of the first dynamic-responsive polymer changes gradually, but the information is still hidden.

[0074] After being kept in the dark for a period of time (e.g., 1 hour) and then irradiated again: the first type of dynamic responsive polymer directly emits the second color fluorescence, while the second type of dynamic responsive polymer retains the first color, and the second color information appears instantly.

[0075] Example 1 This embodiment provides an AIE polymer, which is polymerized from raw materials including compounds containing diphenylmethane structures and their derivatives, compounds containing sulfur-containing side chains or directly linked sulfur-containing groups, and a polymer matrix material. The compound containing diphenylmethane structures and their derivatives is 4,4'-diaminodiphenylmethane MDA, the compound containing sulfur-containing side chains or directly linked sulfur-containing groups is dimethylthiotoluene diamine, and the polymer matrix material is epoxy resin E51. The molar ratio of dimethylthiotoluene diamine, MDA, and epoxy resin E51 is 1:1:2.

[0076] This embodiment also provides a method for synthesizing the AIE polymer, including the following steps: Dimethylthiotoluene diamine (10 mmol) and MDA (10 mmol of 4,4'-diaminodiphenylmethane) were added to DMF and dissolved thoroughly. Triethylamine (0.4 mmol) was then added and mixed thoroughly. The mixture was heated to 80 °C and epoxy resin E51 (20 mmol) was added. After mixing for 3 h under a nitrogen atmosphere, the mixture was poured into a mold preheated to 110 °C and cured in an 80 °C oven for 2 days to obtain the target polymer. The resulting polymer was then irradiated under a 365 nm 20 W UV-LED lamp. The synthesized sample was named HY-0.5MDA0.5DM. Specific structural characterization and luminescence behavior are detailed in [link to documentation]. Figure 3 and Figure 4 .

[0077] Depend on Figure 3 As can be seen, the polymer successfully emitted a deep red fluorescence. However, the polymer in this example does not automatically de-excite at room temperature after entering the excited state, but needs to be heated at 80°C for at least 1 minute.

[0078] Depend on Figure 4 It can be seen that the fluorescence emitted by the polymer in this embodiment is in the red range, and some wavelengths extend to the near-infrared range. At the same time, multiple n-π* transition signals were observed in the UV-Vis diffuse reflectance absorption spectrum, and an increase in the C=S signal was observed in the Raman spectrum. This proves that the formation of C=S between the diphenylmethane structure and the sulfur-containing side chain is the mechanism by which the polymer generates fluorescence signals.

[0079] Example 2 This embodiment provides an AIE polymer, which is polymerized from raw materials including compounds containing diphenylmethane structures and their derivatives, compounds containing sulfur-containing side chains or directly linked sulfur-containing groups, and polyester polyols. The compound containing diphenylmethane structures and their derivatives is diphenylmethane diisocyanate (MDI), the compound containing sulfur-containing side chains or directly linked sulfur-containing groups is dimethylthiotoluene diamine, and the polyester polyol is PCL2000. The molar ratio of MDI, dimethylthiotoluene diamine, and PCL2000 is 10:8:2.

[0080] This embodiment also provides a method for synthesizing the AIE polymer, including the following steps: MDI (diphenylmethane diisocyanate, 30 mmol) and PCL2000 (6 mmol) were added to a dried three-necked flask, followed by 5 ml of DMF and DBTDL (0.07 mmol). The mixture was then reacted at 80 °C for 4 h. After the NCO% was determined by toluene-di-n-butylamine titration and reached the target value, the prepolymer was sealed and stored for later use. Dimethylthiotoluene diamine chain extender was added to the prepolymer according to a specific chain extension coefficient. After thorough mixing, the mixture was cured at room temperature for 1 h to obtain the target polymer. The obtained polymer was then irradiated under a 365 nm 20 W UV-LED lamp. The synthesized sample was named MDI100-1DM. Specific structural characterization and luminescence behavior are detailed in [link to relevant documentation]. Figures 5-7 .

[0081] Depend on Figure 5 It can be seen that when the original sample is continuously irradiated, its fluorescence phenomenon is not obvious. After long-term irradiation, the polymer gradually produces significant orange fluorescence, and the sample itself also begins to turn red. After being placed in the dark, the color and luminescence behavior of the sample return to the initial state. The whole process is divided into the original, excited and de-excited states.

[0082] Depend on Figure 6 It can be seen that, Figure 6 (a) The overall shift of the excited-state curves in the UV-Vis absorption spectrum towards longer wavelengths indicates an increase in the overall conjugation degree of the material. Simultaneously, a new absorption peak was observed around 520 nm in the R absorption band, confirming the existence of the n-π* transition in the excited state and the reversible process. (See the Raman spectrum.) Figure 6 (b) A change in the characteristic peak at 1055 cm⁻¹ was captured, which is generally considered to be related to C=S. The emission and excitation spectra of steady-state fluorescence are as follows: Figure 6 As shown in (c), in addition to fluorescence, there is also a small amount of phosphorescence, which further verifies the contribution of lone pair electrons in C=S.

[0083] Depend on Figure 7 It can be seen that the peak value at CS (163.57 eV) in the in-situ irradiated XPS sulfur fine spectrum decreased after irradiation. This is because the sulfur-containing side chain is converted into C=S (163.2 eV) and -SH. However, the peak value at CS rebounded and the peak value at C=S decreased in the de-excitation state, which proves the process of C=S converting into CS.

[0084] Example 3 This embodiment provides an AIE polymer, which is polymerized from raw materials including compounds containing diphenylmethane structures and their derivatives, compounds containing sulfur-containing side chains or directly connected sulfur-containing groups, and polyether polyols. The compound containing diphenylmethane structures and their derivatives is diphenylmethane diisocyanate (MDI), the compound containing sulfur-containing side chains or directly connected sulfur-containing groups is pentaerythritol tetrakis(3-mercaptopropionic acid) thiols, and the polyether polyol is PTEMG2000. The molar ratio of MDI, pentaerythritol tetrakis(3-mercaptopropionic acid) thiols, and PTEMG2000 is 10:4:2.

[0085] This embodiment also provides a method for synthesizing the AIE polymer, including the following steps: MDI (30 mmol) and PTEMG2000 (6 mmol) were added to a dried three-necked flask, followed by 5 ml of DMF and DBTDL (0.07 mmol). The mixture was then reacted at 80 °C for 4 h. After the NCO% was determined by toluene-di-n-butylamine titration and reached the target value, the prepolymer was sealed and stored for later use. A pentaerythritol tetrakis(3-mercaptopropionic acid) chain extender was added to the prepolymer with a chain extension coefficient of 1. After thorough mixing, the mixture was cured in an oven at 80 °C for 7 days to obtain the target polymer. The obtained polymer was then irradiated under a 365 nm 20 W UV-LED lamp. The synthesized sample was named MDI100-1S. Specific structural characterization and luminescence behavior are detailed in [link to relevant documentation]. Figure 8 .

[0086] Depend on Figure 8 It can be seen that the polymer emits orange-yellow fluorescence, and its wavelength is shorter than that of the polymer in Example 3. This indicates that the electron-donating ability and the degree of electron orbital conjugation of the groups connected to the sulfur-containing side chains affect the fluorescence wavelength of the polymer. This further illustrates that the target structure formed by diphenylmethane and the sulfur-containing side chains is the luminescence mechanism of the polymer described in this invention.

[0087] Example 4 Based on Example 3, the target polymer obtained was subjected to 365 nm UV exposure for 6 hours to obtain a novel AIE polymer emitting green light. Figure 9 ).Depend on Figure 9 As can be seen, after prolonged irradiation, the polymer in Example 3 gradually changed into green fluorescence, which indicates a unique luminescence behavior and represents a method for preparing a class of green fluorescent polymers.

[0088] Example 5 This embodiment provides an AIE polymer, which is polymerized from raw materials including compounds containing diphenylmethane structures and their derivatives, compounds containing sulfur-containing side chains or directly linked sulfur-containing groups, and polyether polyols. The compound containing diphenylmethane structures and their derivatives is diphenylmethane diisocyanate (MDI), and the compound containing sulfur-containing side chains or directly linked sulfur-containing groups is dimethylthiotoluene diamine and 3,6-dioxo-1,8-octanedithiol. The molar ratio of MDI, dimethylthiotoluene diamine, 3,6-dioxo-1,8-octanedithiol, and PTEMG2000 is 10:8:4.7:2.

[0089] This embodiment also provides a method for synthesizing the AIE polymer, including the following steps: MDI (30 mmol) and PTEMG2000 (6 mmol) were added to a dried three-necked flask, followed by 5 ml of DMF and DBTDL (0.07 mmol). The mixture was then reacted at 80 °C for 4 h. The NCO% was determined by toluene-di-n-butylamine titration. Once the target value was reached, the prepolymer was sealed and stored for later use.

[0090] Dimethylthiotoluene diamine chain extender with a chain extension coefficient of 1 was added to the prepolymer, along with 3,6-dioxa-1,8-octanedithiol. After thorough mixing, the mixture was cured in an oven at 80°C for 7 days to obtain the target polymer. The obtained polymer was then irradiated under a 365 nm 20 W UV-LED lamp. By controlling the exposure time under the UV light source, the wavelengths of initial emission and steady-state emission could be controlled. Figure 10 ),Depend on Figure 10 As can be seen, after prolonged irradiation, the polymer fluorescence in this embodiment gradually transitions from orange to yellow (process 1), and after being stored in the dark, the initial excitation wavelength changes to green (process 2).

[0091] Example 6 This embodiment provides an AIE polymer, which is polymerized from raw materials including compounds containing diphenylmethane structures and their derivatives, compounds containing sulfur-containing side chains or directly connected sulfur-containing groups, and polyester polyols. The compound containing diphenylmethane structures and their derivatives is diphenylmethane diisocyanate (MDI), the compound containing sulfur-containing side chains or directly connected sulfur-containing groups is 2-methylthiopyrimidine-4,6-diamine, and the polyester polyol is PCL2000. The molar ratio of MDI, 2-methylthiopyrimidine-4,6-diamine, and PCL2000 is 10:8:2.25.

[0092] This embodiment also provides a method for synthesizing the AIE polymer, including the following steps: Synthesis of Novel AIE Polyurethane: MDI-based Prepolymer Synthesis: MDI100 (40 mmol) and PCL2000 (9 mmol) were added to a dried three-necked flask, followed by 10 ml of DCM and DBTDL (0.11 mmol), and reacted at 80 °C for 3 h. (This step can be skipped if industrial-grade MDI-based prepolymer is purchased directly). The prepolymer solution was preheated to 60 °C. Following a chain extension coefficient of 1, the prepolymer solution was mixed thoroughly with 2-methylthiopyrimidine-4,6-diamine dissolved in DMF. DBTDL (0.2 mmol) was added, and the mixture was reacted at 90 °C for 12 h. The mixture was then poured into a mold preheated to 120 °C and placed in a drying oven at 80 °C for 2 days for complete curing.

[0093] Example 7 The polymer from Example 2 is designated as PU1.

[0094] A polymer PU2 is provided, the synthesis method of which is based on the synthesis method of Example 2, the only difference being that: when adding the chain extender in the polymer synthesis step, 2% by mass of benzoin dimethyl ether of the prepolymer is added simultaneously.

[0095] A polymer PU3 is provided, the synthesis method of which is based on the synthesis method of Example 2, the only difference being that 15% by mass of 3,6-dioxa-1,8-octanedithiol of the prepolymer is added simultaneously with the chain extender in the polymer synthesis step.

[0096] Encryption and decryption process: 1. Process PU1 and PU2 into specific information, then irradiate them under a UV lamp for 30 seconds, followed by placing them in the dark for 6-8 minutes, and then immediately expose them to light to obtain the encrypted information (see...). Figure 11 , Figure 12 , Figure 13 ).Depend on Figure 11 It can be seen that the fluorescence behavior of the fluorescent polymer used in Process 1 changes over time. Therefore, the rate of change of the polymer's fluorescence behavior over time can be used to program the encryption or decryption of information. Figure 12 It can be seen that the fluorescence behavior of the polymer with the added photoinitiator changes significantly faster than that without it. This provides a way to modulate the rate of change in fluorescence behavior over time. Figure 13It can be seen that by combining the two methods mentioned above, 4D fluorescence encryption technology was successfully achieved. The fluorescent polymer without photoinitiator was made into special information and mixed into the polymer material array with photoinitiator. During the excitation process, the special information could not be identified. However, during the light-proof and static process, the presence of photoinitiator will greatly accelerate the de-excitation process of polymer fluorescence. Therefore, there is a time difference between the de-excitation of the unencrypted information polymer and the non-de-excitation of the encrypted information polymer. Illumination within this time difference can decrypt the corresponding encrypted information.

[0097] 2. Process PU1 and PU3 into specific information, then irradiate them under a UV lamp for 30 minutes to obtain encrypted information (see...). Figure 14 , Figure 15 ).Depend on Figure 14 It can be seen that the PU3 polymer undergoes the fluorescence behavior changes described in Example 4 under prolonged light exposure. This change in fluorescence behavior under light exposure can realize 4D fluorescence encryption technology. Figure 15 It can be seen that by taking advantage of the characteristic that the fluorescence wavelength of PU3 gradually shortens under illumination, the encrypted information (PU3) and the unencrypted information (PU1) are mixed and placed together and continuously illuminated, and the encrypted information can be displayed after a period of time.

[0098] 3. Process PU1 and PU3 into specific information, then irradiate them under a UV lamp for 30 minutes, let them stand in the dark for 1 hour, and then turn on the UV lamp again to obtain the encrypted information (see...). Figure 16 ),Depend on Figure 16 It can be seen that by utilizing the characteristic that the initial excitation wavelength of PU3 is green after long-term light exposure, another 4D encryption technology can be completed. After mixing encrypted information (PU3) and unencrypted information (PU1) and placing them together, they are continuously exposed to light for 30 minutes. Then, PU1 and PU3 are placed in the dark for 1 hour, and then exposed to light again. The green encrypted information can be clearly detected by light.

[0099] Example 8 The polymer from Example 1 is denoted as E1.

[0100] A polymer E2 is provided, which is polymerized from epoxy resin and polyether polyol. The epoxy resin is E51, and the polyether polyol is PPG-5000. The molar ratio of E51 to PPG-5000 is 1:1. The synthesis method of polymer E2 includes the following steps: preheating PPG-5000 (10 mmol) to 65°C, then adding triethylamine (0.4 mmol) and mixing thoroughly. The temperature is then raised to 80°C, and epoxy resin E51 (10 mmol) and rhodamine B (5 mmol) are added. After mixing for 3 hours under a nitrogen atmosphere, the mixture is poured into a mold preheated to 110°C, and then cured in an oven at 80°C for 2 days to obtain the target polymer.

[0101] Encryption and decryption process: E1 is processed into specific information, irradiated under a UV lamp for 30 seconds to fully excite it, and then mixed with a static red fluorescent material (denoted as E2). At this point, the encryption process is complete, and decryption is impossible regardless of UV irradiation. The mixed material is placed in a 60℃ oven for 30 minutes. Upon re-irradiation, E1 does not immediately emit light, thus decrypting the specific information. Figure 17 , Figure 18 ),Depend on Figure 17 It can be seen that E1 exhibits a unique fluorescence behavior: its red fluorescence disappears after heating to 80℃. This fluorescence behavior is significantly different from that of ordinary fluorescent polymers, and therefore can be used for information encryption. Figure 18 It can be seen that when E1 and E2 are irradiated with ultraviolet light together, both emit red fluorescence. Then, when both are heated at 80°C and irradiated again after heating, it can be found that the red fluorescence of the E1 polymer containing the encrypted information disappears, thus completing the decryption process.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamically responsive polymer with aggregation-induced emission properties, characterized in that, It is polymerized from raw materials including compounds containing diphenylmethane structure and its derivatives and compounds containing sulfur-containing side chains or directly connected sulfur-containing groups.

2. The dynamically responsive polymer according to claim 1, characterized in that, The compound containing sulfur-containing side chains or directly connected sulfur-containing groups contains one or more of methylthio, ethylthio, and mercapto groups.

3. The dynamically responsive polymer according to claim 1, characterized in that, The compounds containing diphenylmethane structures and their derivatives include one or more of 4,4'-diaminodiphenylmethane, diphenylmethane diisocyanate, 2,2'-methylenediphenol, N,N,N,N'-tetraglycidyl-4,4-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(2-ethyl)aniline, 4,4'-bismaleimide diphenylmethane, and 4,4'-methylenebis[N-sec-butylaniline] and bis(4-hydroxyphenyl)aniline.

4. The dynamically responsive polymer according to claim 1, characterized in that, The compounds containing sulfur-containing side chains or directly linked sulfur-containing groups include one or more of dimethylthiotoluene diamine, pentaerythritol tetra(3-mercaptopropionate), 3-aminobenzylthiophenol, diaminobenzylthiophenol, 4-aminobutane-1-thiol, 4-hydroxybenzylthiol, 4,6-dihydroxy-2-methylthiopyrimidine, 4-(methylthio)phenyl-1,2-diamine, 3,6-dioxa-1,8-octanedithiol, dimercaptoethanol, and 2-(methylthio)-5-aminopyrimidine.

5. The dynamically responsive polymer according to claim 1, characterized in that, The molar ratio of the compound containing the diphenylmethane structure and its derivatives to the compound containing the sulfur-containing side chain or directly connected sulfur-containing group is less than 10:

1.

6. The dynamically responsive polymer according to claim 1, characterized in that, The raw materials for preparation also include polymer matrix materials with aromatic structures; Preferably, the molar ratio of the polymer matrix material to the compound containing sulfur-containing side chains or directly connected sulfur-containing groups is (1-3):1; Preferably, the polymer matrix material is a compound containing epoxy functional groups.

7. The dynamically responsive polymer according to claim 1, characterized in that, The raw materials also include polyether polyols or polyester polyols, and the molar ratio of the compound containing the diphenylmethane structure and its derivatives to the polyether polyol or polyester polyol is (3-8):

1.

8. A method for preparing the dynamically responsive polymer according to any one of claims 1-7, characterized in that, Compounds containing diphenylmethane structures and their derivatives, and compounds with sulfur-containing side chains or directly connected sulfur-containing groups, are polymerized under conditions where free radical scavengers and free radical terminators are absent.

9. The preparation method according to claim 8, characterized in that, The polymerization reaction is a random copolymerization, block copolymerization, or alternating copolymerization. Preferably, the polymerization reaction is carried out under conditions of a photoinitiator and / or a crosslinking agent; More preferably, the photoinitiator is selected from one or more of benzoin dimethyl ether, 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, and 2-isopropylthioxanthone; the crosslinking agent is selected from one or more of 3,6-dioxa-1,8-octanedithiol, pentaerythritol tetra-3-mercaptopropionate, and trimethylolpropane tris(3-mercaptopropionate).

10. The application of the dynamically responsive polymer according to any one of claims 1-7 in 4D dynamic anti-counterfeiting encryption; Preferably, the application method uses at least two different dynamic responsive polymers to perform 4D dynamic anti-counterfeiting encryption under light irradiation; more preferably, the at least two different dynamic responsive polymers satisfy different emission rates and / or emission wavelengths.

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