Chemically responsive shape memory polymers with enhanced fluorescence, methods of making and uses thereof

Abstract

The present application relates to the field of polymer materials and information anti-counterfeiting technology, and in particular to a shape memory polymer with chemically responsive fluorescence enhancement, a preparation method and applications. A polycarbonate crosslinked network material with shape memory performance is constructed, the material has stable and reversible heat-induced shape memory behavior, temporary shape programming and recovery can be achieved through thermal stimulation, and no exogenous fluorescent groups need to be introduced, the material has intrinsic luminescence characteristics under ultraviolet light irradiation, local chemical treatment by acid or amine can achieve local area fluorescence intensity enhancement, thereby realizing fluorescence information patterning; and a multi-level anti-counterfeiting system integrating "deformation-optical-thermal" multiple information is further constructed. The present application has the advantages of simple preparation method, green material source, no need to add additional fluorescent dyes or light-emitting components, and the obtained anti-counterfeiting material has information hiding, dynamic reading and multiple verification characteristics, and has application value in the fields of intelligent anti-counterfeiting labels, information encryption materials and high security anti-counterfeiting.

Description

Technical Field

[0001] This invention relates to the fields of polymer materials and information anti-counterfeiting technology, specifically to chemically responsive fluorescence-enhanced shape memory polymers, their preparation methods, and applications. Background Technology

[0002] With the continuous development of counterfeiting technology, traditional anti-counterfeiting methods (such as QR codes and ordinary fluorescent layers) are easily imitated and cracked because they usually rely on static two-dimensional information storage, leading to an increasing risk of information leakage. The market demand for advanced anti-counterfeiting materials with higher security levels, dynamic encryption capabilities, and multimodal verification has surged. To address this challenge, researchers have developed numerous advanced anti-counterfeiting systems, including room temperature phosphorescence, dynamic chromaticity, and multiple stimulus responses. Among these, multimodal anti-counterfeiting materials based on the combination of shape memory effect and fluorescence response have attracted widespread attention due to their high security, ease of design, and convenient patterning capabilities.

[0003] However, existing shape memory fluorescent anti-counterfeiting systems still face many challenges: the extensive use of traditional petroleum-based polymers exacerbates the depletion of fossil resources and long-term ecological pollution problems. Furthermore, most reported fluorescent anti-counterfeiting materials require the introduction of additional rare-earth complexes, quantum dots, or conjugated luminescent agents to achieve light output. While these strategies offer tunable luminescence properties, they typically involve complex synthesis processes and high manufacturing costs. Moreover, the introduction of exogenous luminescent agents often carries potential toxicity and limited environmental sustainability, failing to meet the requirements of modern green chemistry. In addition, existing anti-counterfeiting systems are mostly limited to single or dual decryption dimensions (such as "light-shape" dual-mode), and their encryption complexity and security remain insufficient in dealing with increasingly sophisticated counterfeiting methods, making it difficult to achieve multi-level deep encryption and perfect concealment.

[0004] Therefore, developing an environmentally and bio-friendly smart polymer anti-counterfeiting material that can integrate multi-dimensional responses to achieve advanced information encryption is a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a chemically responsive fluorescence-enhanced shape memory polymer, its preparation method, and its application, in order to solve the problems of traditional anti-counterfeiting materials that rely on external light sources, have poor environmental compatibility, and have limited encryption methods that are easily cracked.

[0006] To achieve the above objectives, the present invention employs the following technical solution: a chemically responsive fluorescence-enhanced shape memory polymer, wherein the shape memory polymer is an aliphatic polycarbonate crosslinking network obtained by photocuring and crosslinking of double-bond-terminated polycarbonate through a thiol-ene click reaction, possessing intrinsic fluorescence characteristics and thermally induced shape memory properties; the fluorescence intensity is enhanced by chemical treatment with chemical reagents; the polymer is heated to enter a deformable state, forming a temporary shape under external force, and recovering its initial shape under subsequent thermal stimulation.

[0007] Furthermore, the double-bond-terminated polycarbonate is a double-bond-terminated aliphatic polycarbonate network formed by the acylation reaction of polycarbonate diol.

[0008] Furthermore, the polycarbonate diol is obtained by polycondensation reaction of diethyl carbonate and 1,4-butanediol; the acylating agent for the acylation reaction includes acryloyl chloride; the crosslinking agent for the thiol-ene click reaction photocuring crosslinking includes pentaerythritol tetra-3-mercaptopropionate; the chemical reagents include acids or amines, the acids including acetic acid, and the amines including n-propylamine.

[0009] The preparation method of the above-mentioned shape memory polymer includes the following steps: S1. Diethyl carbonate and 1,4-butanediol are added to a catalyst and reacted to obtain polycarbonate diol; S2. Dissolve the polycarbonate diol obtained in S1 and add acryloyl chloride dropwise to carry out an acylation reaction to obtain double-bond-terminated polycarbonate. S3. Dissolve the double-bond-terminated polycarbonate and mix it with a multifunctional thiol crosslinking agent and a photoinitiator. Under ultraviolet light irradiation, a thiol-olefin click crosslinking reaction occurs to obtain an aliphatic polycarbonate crosslinking network.

[0010] Further, in S1, the catalyst includes 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and the molar ratio of [1,4-butanediol]:[diethyl carbonate]:[1,5,7-triazabicyclo[4.4.0]dec-5-ene] is 1.1~1.3:1:0.005~0.015.

[0011] Furthermore, in S1, the reaction is carried out under a nitrogen atmosphere. The reaction mixture is first stirred and reacted at 85-95°C for 10-15 hours, and then the temperature is raised to 150-180°C for 2-5 hours.

[0012] Furthermore, S2 also includes an acid-binding agent, which includes triethylamine; the molar equivalent ratio of polycarbonate diol to acryloyl chloride is 1:3~4.

[0013] Furthermore, S3 also includes a photoinitiator, which includes TPO; the molar equivalent ratio of double-bonded polycarbonate to crosslinking agent is 1:0.8~1.2; curing is performed under a 320~390nm UV lamp for 15~25min and drying at room temperature for 20~30h.

[0014] The aforementioned shape memory polymers are used as anti-counterfeiting materials, including smart anti-counterfeiting labels, information encryption materials, anti-counterfeiting packaging materials, and / or dynamic information display materials.

[0015] Furthermore, by integrating fluorescent patterning, three-dimensional programmable deformation, and thermal conversion parameters, a multi-dimensional anti-counterfeiting platform with light-shape-thermal coupling encryption is constructed to match the functional requirements of multi-modal anti-counterfeiting and information encryption.

[0016] The beneficial effects of this invention are: 1. The anti-counterfeiting material prepared by this invention uses aliphatic polycarbonate synthesized from monomers from renewable sources, which endows the anti-counterfeiting system with inherent sustainability and biocompatibility, effectively reducing the ecological burden caused by traditional petroleum-based plastics.

[0017] 2. Compared with traditional optical anti-counterfeiting materials that rely on the introduction of rare earth complexes or quantum dots as external light sources, this invention cleverly utilizes the cluster light emission characteristics based on spatial conjugation. By simply wiping with glacial acetic acid or n-propylamine, local fluorescence enhancement can be achieved, and desired patterns can be printed, realizing dye-free chemical encryption, which greatly reduces manufacturing costs and environmental risks.

[0018] 3. This invention constructs a multi-dimensional anti-counterfeiting platform that integrates "light-shape-heat". In addition to primary ultraviolet fluorescence and reversible deformation concealment, it innovatively introduces the material's inherent stable thermal transition temperature (such as Tm) as the intrinsic "thermal fingerprint" for multi-level decoding. This three-stage logic encryption significantly enhances the complexity, barriers and security of anti-counterfeiting. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the preparation and structure of the aliphatic polycarbonate crosslinked polymer network of the present invention; Figure 2 This is a schematic diagram of the thermally induced reversible shape memory process of the polycarbonate crosslinked film of the present invention; Figure 3 This is a schematic diagram of the acid-base stimulation-induced polymer fluorescence enhancement and patterned information writing process of the present invention; Figure 4 This is a schematic diagram of the multi-level anti-counterfeiting application based on fluorescence enhancement and shape memory effect of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0021] The preparation process of the shape memory polymer of this invention is as follows: 1. Polymer synthesis via polycondensation reaction Diethyl carbonate, 1,4-butanediol, and catalyst were added to a flask at a fixed feed ratio. The mixture was first stirred in an oil bath until equilibrium was reached, and then heated to allow for compression polymerization. After cooling the mixture to room temperature, it was dissolved in dichloromethane, washed with cold methanol precipitation, and dried under vacuum to obtain polycarbonate diol (PCD) powder.

[0022] 2. Acylation capping reaction Polycarbonate diol was dissolved in dichloromethane, triethylamine was added as an acid-binding agent, and the mixture was placed in an ice-water bath. Acryloyl chloride solution was slowly added dropwise while stirring. After the reaction was completed, the mixture was concentrated by rotary evaporation, then precipitated and washed in ice-cold methanol and dried under vacuum to obtain acryloyl chloride-terminated polycarbonate (PC-DA).

[0023] 3. Preparation of network membranes by photocuring crosslinking Acryloyl chloride-terminated polycarbonate prepolymer was dissolved in an appropriate amount of dichloromethane, and pentaerythritol tetra-3-mercaptopropionate crosslinking agent and photoinitiator were added. After vortex mixing, the mixture was poured into a mold. Subsequently, it was cured under a 365nm ultraviolet lamp, and finally the polymer network was dried to prepare a crosslinked aliphatic polycarbonate network (PC-X) film.

[0024] 4. Acid amine enhances fluorescent anti-counterfeiting A pre-designed pattern mask was prepared using laser engraving technology and then applied to the surface of a pre-prepared cross-linked aliphatic polycarbonate network film. The exposed areas were then locally wiped with glacial acetic acid or n-propylamine to achieve precise printing of the pattern information. Upon excitation with 365nm ultraviolet light, the treated areas exhibited significant fluorescence enhancement, displaying a clear fluorescence contrast with the untreated areas and clearly revealing the pre-designed pattern information.

[0025] Example 1 The preparation process of the anti-counterfeiting substrate is as follows: Under a nitrogen atmosphere, [1,4-butanediol]:[diethyl carbonate]:[1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)] = 1.2:1:0.01 was fed into a 50 mL flask. The mixture was first stirred in an oil bath at 90 °C for 12 h, and then heated to 160 °C for compression polymerization for 4 h. The mixture was cooled to room temperature and dissolved in dichloromethane, washed with cold methanol precipitation, and dried under vacuum to obtain a white polycarbonate diol powder.

[0026] 15g of the above polycarbonate diol was dissolved in 75mL of dichloromethane, and 3.7 molar equivalents of triethylamine were added. The mixture was placed in an ice-water bath, and 3.4 molar equivalents of acryloyl chloride diluted with 15mL of dichloromethane were slowly added dropwise with stirring. The addition process was carried out in an ice-water bath, and the reaction was continued for 24h. After rotary evaporation and concentration, the product was precipitated and washed in ice-cold methanol and dried under vacuum to obtain the polycarbonate prepolymer with acryloyl chloride end-capping.

[0027] 1g of acryloyl chloride-terminated prepolymer was dissolved in 1mL of dichloromethane, and 1 equivalent of pentaerythritol tetra-3-mercaptopropionate (PETMP) crosslinking agent and 4mg of TPO photoinitiator were added. After mixing evenly, the mixture was poured into a 2×2cm polytetrafluoroethylene mold and cured under a 365nm UV lamp at a distance of 5cm for 20min. The mixture was then dried at room temperature for 24h to obtain a polycarbonate crosslinked film (PC-X).

[0028] Example 2 Based on the thin film prepared in Example 1, an acid-amine printing luminescence enhancement and multimodal encryption anti-counterfeiting system was constructed: A mask with a pre-defined pattern was prepared using laser engraving technology and applied to the surface of a PC-X film. The exposed areas were then locally wiped with glacial acetic acid or n-propylamine. After treatment, the material underwent local hydrolysis or ammonolysis, which caused network rearrangement and altered the spatial conjugation effect. The pattern exhibited excellent concealment under natural light, while under 365nm ultraviolet light excitation, the wiped areas showed bright blue fluorescence enhancement, achieving information writing without an external light source.

[0029] By utilizing the unique bidirectional reversible deformation law of this cross-linked network to mask information, the film printed with fluorescent information is heated to a completely molten state, programmed into a specific shape (temporary shape) by external force, and then cooled at room temperature to lock the temporary shape.

[0030] The material undergoes a certain deformation when heated to a semi-crystalline, semi-molten state, and spontaneously recovers at room temperature. Decryption requires a three-stage logic: the first stage involves reading the fluorescent code of the initial shape under ultraviolet light; the second stage involves a specific thermal triggering temperature (such as T). H =39℃) and the fluorescent encoding displayed after the material deformation; the third layer is to use differential scanning calorimetry (DSC) to obtain its constant melting temperature (Tm=46±1℃) after complete crystallization as the internal "thermal fingerprint" code, and complete the final joint decoding.

[0031] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this invention falls within the protection scope of this invention.

Claims

1. A chemically responsive fluorescence-enhanced shape memory polymer, characterized in that: The shape memory polymer is an aliphatic polycarbonate crosslinking network obtained by photocuring and crosslinking of double-bond-terminated polycarbonate through a thiol-ene click reaction. It has intrinsic fluorescence properties and thermally induced shape memory properties. The fluorescence intensity is enhanced by chemical treatment with chemical reagents. The polymer is heated to enter a deformable state, forms a temporary shape under external force, and recovers its initial shape under subsequent thermal stimulation.

2. The chemically responsive fluorescence-enhanced shape memory polymer according to claim 1, characterized in that: The double-bond-terminated polycarbonate is a double-bond-terminated aliphatic polycarbonate network formed by the acylation reaction of polycarbonate diol.

3. The chemically responsive fluorescence-enhanced shape memory polymer according to claim 2, characterized in that: The polycarbonate diol is obtained by polycondensation reaction of diethyl carbonate and 1,4-butanediol; the acylating agent for the acylation reaction includes acryloyl chloride; the crosslinking agent for the thiol-ene click reaction photocuring crosslinking includes pentaerythritol tetra-3-mercaptopropionate; the chemical reagents include acids or amines, the acids including acetic acid, and the amines including n-propylamine.

4. The method for preparing the shape memory polymer according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Diethyl carbonate and 1,4-butanediol are added to a catalyst and reacted to obtain polycarbonate diol; S2. Dissolve the polycarbonate diol obtained in S1 and add acryloyl chloride dropwise to carry out an acylation reaction to obtain double-bond-terminated polycarbonate. S3. Dissolve the double-bond-terminated polycarbonate and mix it with a multifunctional thiol crosslinking agent and a photoinitiator. Under ultraviolet light irradiation, a thiol-olefin click crosslinking reaction occurs to obtain an aliphatic polycarbonate crosslinking network.

5. The preparation method according to claim 4, characterized in that: In S1, the catalyst includes 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and the molar ratio of [1,4-butanediol]:[diethyl carbonate]:[1,5,7-triazabicyclo[4.4.0]dec-5-ene] is 1.1~1.3:1:0.005~0.

015.

6. The preparation method according to claim 4, characterized in that: In S1, the reaction is carried out under a nitrogen atmosphere. The reaction mixture is first stirred and reacted at 85-95°C for 10-15 hours, and then heated to 150-180°C for 2-5 hours.

7. The preparation method according to claim 4, characterized in that: The S2 further includes an acid-binding agent, which includes triethylamine; the molar equivalent ratio of polycarbonate diol to acryloyl chloride is 1:3~4.

8. The preparation method according to claim 4, characterized in that: The S3 also includes a photoinitiator, which includes TPO; the molar equivalent ratio of double-bonded polycarbonate to crosslinking agent is 1:0.8~1.2; curing is performed under a 320~390nm UV lamp for 15~25min and drying at room temperature for 20~30h.

9. The shape memory polymer according to any one of claims 1-3 is used as an anti-counterfeiting material, characterized in that: The anti-counterfeiting materials include smart anti-counterfeiting labels, information encryption materials, anti-counterfeiting packaging materials, and / or dynamic information display materials.

10. The application according to claim 9, characterized in that: By integrating fluorescent patterning, three-dimensional programmable deformation, and thermal conversion parameters, a multi-dimensional anti-counterfeiting platform with light-shape-thermal coupling encryption is constructed to match the functional requirements of multi-modal anti-counterfeiting and information encryption.

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