Poly-eutectic stimulus-responsive fluorescent gel as well as preparation method and application thereof
By using free radical polymerization of monomeric hydrogen bond acceptors and donors, and combining guanine nucleoside to regulate hydrogen bond density, a highly stable polyeutectic stimuli-responsive fluorescent gel with good optical transmittance was prepared, solving the problems of unstable performance and high cost in existing technologies. It can be applied to anti-counterfeiting, information encryption and flexible electronic devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-03-10
AI Technical Summary
Existing polyeutectic stimuli-responsive fluorescent gels exhibit unstable performance in long-term high-humidity environments, and their production costs and processes are complex, while their optical transmittance is limited.
A fluorescent gel was prepared by using monomeric hydrogen bond acceptors and donors to form a covalently bonded and physically entangled gel network through free radical polymerization. Guanine nucleoside was added to adjust the hydrogen bond density. A polymerizable eutectic solvent was used as a substrate, and ultraviolet light-initiated polymerization was used to initiate the polymerization.
A fluorescent gel with high stability, good optical transmittance and mechanical properties has been developed, which is suitable for anti-counterfeiting, information encryption and flexible electronic devices, and has self-healing and metal ion responsive properties.
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Figure CN121627985A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fluorescent gel technology, specifically relating to a polyeutectic group stimulus-responsive fluorescent gel. This invention also relates to the preparation method and application of the fluorescent gel. Background Technology
[0002] Stimulus-responsive fluorescent gels are a class of soft materials in which fluorescent substances are embedded in three-dimensional gel materials through covalent or non-covalent interactions. They exhibit luminescence response under specific stimuli and are therefore widely used in materials science, smart sensing, information storage, and biomedicine. Based on the different solvent types used in constructing the three-dimensional network of stimulus-responsive fluorescent gels, the substrates can be divided into three main categories: hydrogels, ionic gels, and polyeutectic gels. Hydrogel substrates are prone to water evaporation or crystallization in high or low temperature environments, leading to changes in the substrate's structure or properties and significantly limiting their application. Compared to hydrogel substrates, ionic gel substrates, while possessing good conductivity and stability, typically introduce organic solvents and conductive fillers during preparation, increasing production costs, complicating processes, and reducing environmental friendliness. Polyeutectic gel substrates are a novel type of soft gel prepared using a eutectic solvent (DES) composed of two or more substances mixed in a certain proportion. They offer better environmental stability, are inexpensive, have a simple preparation process, and are non-toxic and biodegradable.
[0003] Currently, the mainstream preparation method for polyeutectic stimuli-responsive fluorescent gels is to use DES made from hydrogen bond acceptors (HBA, such as choline chloride) and monomeric hydrogen bond donors (HBD, such as acrylic acid, acrylamide, etc.), further introduce stimuli-responsive fluorescent substances, and finally polymerize to obtain a fluorescent gel based on a polyeutectic gel. For example, He et al. [Chemical Communications, 2020, 56(18): 2771-2774] synthesized choline chloride (HBA) and monomeric acrylic acid (HBD) into a DES, and combined the polymerized eutectic gel substrate with conductive glass and a light-emitting layer to obtain a type of photoluminescent device; further, He et al. [Acs Sustainable Chemistry & Engineering, 2020, 8(13): 5132-5139] used choline chloride as HBA and monomeric acrylamide as HBD to synthesize a polymerizable DES, and further introduced nanocellulose and functional ZnS:Cu powder to polymerize and obtain electroluminescent eutectic gel-based nanopaper; Zhang et al. [Angewandte Chemie-International Edition, 2023, [62(46): e202313971] Based on the multifunctional properties of fluorescent sucker squid, a polyeutectic fluorescent gel material with excellent adhesion and self-healing properties was obtained by in-situ polymerization using choline chloride as HBA, glycerol, monomeric acrylic acid and dynamic photoresponsive functional unit methyl methacrylate-9-anthracene as HBDs; Based on this, Yuan et al. [Chemical Engineering Journal, 2024, 494: 153254] used choline chloride as HBA, monomeric N-(2-hydroxyethyl)acrylamide and phytic acid as multifunctional HBDs, combined to form DES, and then similarly introduced methyl 9-anthracene methacrylate with dynamic photoresponsiveness as a fluorescent unit, and obtained polyeutectic fluorescent gel with tunable and reversible fluorescence by ultraviolet light polymerization. However, during the preparation of the precursors for these polyeutectic fluorescent gels, on the one hand, the hydrogen bond acceptors involved are mainly non-monomeric choline chloride, which may cause the small molecule to migrate and dissolve in a long-term high humidity environment, resulting in performance loss; on the other hand, most of the stimulus-responsive fluorescent fillers in these gels need to be introduced from the outside, which increases the production cost and process complexity of these gels, and the color of the fluorescent filler will also limit the optical transmittance of the gel.
[0004] Therefore, based on the high designability of DES and its rich internal non-covalent interaction network matrix, hydrogen bond donors and acceptors can be designed as monomers when constructing eutectic stimuli-responsive fluorescent gel precursors to participate in subsequent polymerization reactions and ensure their performance stability. In addition, the functional groups within the hydrogen bond donor / acceptor molecules can be further conjugated with the gel network molecules to form a conjugated structure and charge transfer, resulting in good intrinsic fluorescence properties and optical transmittance. Summary of the Invention
[0005] The purpose of this invention is to provide a polyeutectic stimuli-responsive fluorescent gel with good intrinsic fluorescence properties and optical transmittance, as well as high stability and good mechanical properties.
[0006] Another objective of this invention is to provide a method for preparing the above-mentioned fluorescent gel, which uses a polymerizable eutectic solvent as the gel substrate and is characterized by being green and environmentally friendly, and having a simple and rapid preparation process.
[0007] The third objective of this invention is to provide applications of the aforementioned fluorescent gel in the fields of anti-counterfeiting, information encryption, and flexible electronic devices.
[0008] The technical solution adopted in this invention is a method for preparing a polyeutectic group stimulus-responsive fluorescent gel, which is implemented according to the following steps: Step 1: Mix monomeric hydrogen bond acceptor and N-propylene N'-2-hydroxyethylthiourea to obtain mixture A, add deionized water to obtain mixture B, heat and stir mixture B to obtain polymerizable eutectic solvent; Step 2: Add guanine nucleoside, photoinitiator and crosslinking agent to the polymerizable eutectic solvent obtained in Step 1, heat and stir to obtain a prepolymer solution; Step 3: Cast the prepolymer solution obtained in Step 2 into a mold and initiate polymerization under ultraviolet light to obtain a polyeutectic stimuli-responsive fluorescent gel.
[0009] The invention is further characterized by: In step 1, the molar ratio of monomeric hydrogen bond acceptor to N-propene N'-2-hydroxyethylthiourea is 1 to 2:1, and the mass of deionized water is 20 to 40 wt% of the mass of mixture A.
[0010] In step 1, the monomeric hydrogen bond acceptor is one or a mixture of methacryloylethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, (3-methacrylamidopropyl)trimethylammonium chloride, 2-(methacryloyloxy)-N,N,N-trimethylethylammonium methyl sulfate, or N-(2-carboxyethyl)-N,N-dimethylaminoethyl methacrylate inner salt.
[0011] In step 1, mixture B is heated and stirred at 60-70°C for 20-30 minutes.
[0012] In step 2, the photoinitiator is one or a mixture of photoinitiator 2959, 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexylphenyl ketone, or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; The crosslinking agent is one or a mixture of polyethylene glycol diacrylate, N,N-methylenebisacrylamide, or ethylene glycol dimethacrylate.
[0013] In step 2, the amount of photoinitiator added is 1 wt% of the mass of mixture A, the amount of crosslinking agent added is 3 wt% of the mass of mixture A, and the amount of guanine nucleoside added is 5 wt% of the mass of mixture A.
[0014] In step 2, heat and stir at 70-80℃ for 10-15 minutes.
[0015] In step 3, the ultraviolet lamp irradiation parameters are as follows: The ultraviolet lamp has a wavelength of 365nm, a power of 40-60W, a distance of 10-15cm from the sample plane, and an irradiation time of 3-5min.
[0016] Another technical solution adopted in this invention is a polyeutectic stimuli-responsive fluorescent gel, which is prepared by the above method.
[0017] The third technical solution adopted in this invention is the application of polyeutectic stimuli-responsive fluorescent gel in the fields of anti-counterfeiting, information encryption, or flexible electronic devices.
[0018] The beneficial effects of this invention are: (1) The hydrogen bond acceptors and donors selected in this invention are all monomers, which can form a gel network bonded by covalent bonds and physical chain entanglement through free radical polymerization. This can avoid the loss of gel performance caused by the migration and dissolution of traditional hydrogen bond acceptor / donor small molecules in a long-term high humidity environment. (2) The present invention uses monomeric hydrogen bond acceptors, and the raw materials are commercially available. The zwitterionic structure inside methacryloyl ethyl sulfobetaine can provide the gel with good ionic conductivity and self-healing properties. It can also form a stable hydration layer through hydrogen bonding and ion-dipole interaction with water molecules, ensuring its good environmental stability. (3) In this invention, the commercially available monomeric N-propene N'-2-hydroxyethylthiourea is selected as the hydrogen bond donor. The thiourea group inside can act as a hydrogen bond donor to form hydrogen bonds with other molecules in the gel system to enhance the intermolecular interaction, making the molecular arrangement more orderly, thereby affecting the electron cloud distribution and energy transfer process of the molecules, and thus affecting the fluorescence performance of the gel. On the other hand, this structure and functional groups such as hydroxyethyl may participate in the conjugated system of the gel molecules, which changes the length of the conjugated system, the degree of electron delocalization, etc., thereby giving the gel good intrinsic fluorescence performance. It also further avoids the influence of the doping of external fluorescent fillers and the color of fillers on the optical transmittance of the gel. The optical transmittance of this type of gel exceeds 70% in the visible light range. In addition, the intrinsic fluorescence performance also greatly shortens the preparation cycle of the fluorescent gel and the fluorescence performance of the obtained gel is stable. (4) The method of the present invention introduces guanine nucleoside with good biocompatibility as a hydrogen bond density regulator into the polyeutectic fluorescent gel network. The compound can regulate the hydrogen bond network density in the gel through multiple hydrogen bond interactions between molecules and within molecules, thereby further improving its structural stability, mechanical strength and self-healing efficiency. (5) The fluorescent gel of this invention has good ion conductivity, and the assembled sensor can be applied to real-time monitoring of human motion and multi-scenario strain sensing response; in addition, the nitrogen and sulfur atoms in the thiourea molecule of the hydrogen bond donor have lone pairs of electrons, which can react with Cu 2+ and Fe 2+ When metal ions coordinate with each other to form metal chelates, the electronic transition of the fluorescent group is suppressed, resulting in fluorescence quenching. Therefore, the excellent metal ion stimulation response characteristics of this polyeutectic fluorescent gel can also be used in the fields of anti-counterfeiting and information encryption. Attached Figure Description
[0019] Figure 1 The infrared spectrum of the DES prepared in Example 2 of this invention; Figure 2 Differential scanning calorimetry (DSC) of the DES prepared in Example 2 of this invention; Figure 3 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G infrared spectrum; Figure 4 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G differential scan heatmap; Figure 5 The stress-strain curves of the fluorescent gels prepared in Examples 1-3 and Comparative Examples 1-3 of this invention are shown. Figure 6The optical properties of the fluorescent gels prepared in Examples 1-3 and Comparative Examples 1-3 of this invention are shown in the diagram. Figure 7 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G macroscopic self-healing diagram; Figure 8 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G self-healing process diagram under an optical microscope; Figure 9 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G macroscopic electrorepair diagram; Figure 10 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G electrorepair curve; Figure 11 The electrochemical impedance spectroscopy (Figure a) and conductivity (Figure b) of the fluorescent gels prepared in Examples 1-3 of this invention are shown. Figure 12 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G strain sensor map for motion monitoring of different parts of the human body; Figure 13 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G fluorescence emission spectrum; Figure 14 Photographs of "flowers" made using the prepolymer solution prepared in Example 2 of this invention under sunlight and ultraviolet light, and their anti-counterfeiting printing pattern as fluorescent ink; Figure 15 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G photographs taken under sunlight and ultraviolet light after being immersed in solutions of different metal ions at the same concentration (2000 mg / L) for 3 hours, and after being immersed in solutions of different concentrations of Cu. 2+ Photographs of the gel under sunlight and ultraviolet light after 3 hours in a solution of (0 mg / L to 2000 mg / L); Figure 16 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G at different concentrations of Cu 2+ Gel fluorescence intensity distribution after soaking in solutions ranging from 0 mg / L to 2000 mg / L for 3 hours; Figure 17 The fluorescent gel Co-PDES prepared in Example 2 of this invention 1.5 -G is used as a fluorescent ink in the erasure of anti-counterfeiting information. Detailed Implementation
[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0021] The preparation method of the polyeutectic group stimulus-responsive fluorescent gel of the present invention is carried out according to the following steps: Step 1, Preparation of polymerizable eutectic solvent (DES): Mixture A is obtained by mixing a monomeric hydrogen bond acceptor and N-propylene N'-2-hydroxyethylthiourea (AHETU) at a molar ratio of 1 to 2:1. Simultaneously, 20 to 40 wt% of deionized water is added to obtain mixture B. Mixture B is heated and stirred at 60 to 70°C for 20 to 30 minutes to obtain a polymerizable eutectic solvent that remains clear and transparent at room temperature.
[0022] Among them, the monomeric hydrogen bond acceptor is one or a mixture of methacryloylethyl sulfobetaine (SBMA), methacryloyloxyethyl trimethylammonium chloride, (3-methacrylamidopropyl)trimethylammonium chloride, 2-(methacryloyloxy)-N,N,N-trimethylethylammonium methyl sulfate or N-(2-carboxyethyl)-N,N-dimethylaminoethyl methacrylate inner salt.
[0023] Step 2, Prepare the prepolymer solution: Guanine nucleoside, photoinitiator and crosslinking agent are added to the polymerizable eutectic solvent prepared in step 1, and heated and stirred at 70-80°C for 10-15 min to obtain a prepolymer solution; The amount of photoinitiator added is 1 wt% of the mass of mixture A, the amount of crosslinking agent added is 3 wt% of the mass of mixture A, and the amount of guanine nucleoside added is 5 wt% of the mass of mixture A.
[0024] The photoinitiator is one or a mixture of photoinitiator 2959, 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexylphenyl ketone, or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; The crosslinking agent is one or a mixture of polyethylene glycol diacrylate, N,N-methylenebisacrylamide, or ethylene glycol dimethacrylate.
[0025] Step 3, Preparation of polyeutectic stimulus-responsive fluorescent gel: The prepolymer solution obtained in step 2 was cast into a leveled polytetrafluoroethylene mold and polymerization was initiated under ultraviolet light to obtain a polyeutectic stimuli-responsive fluorescent gel.
[0026] The ultraviolet lamp has a wavelength of 365nm, a power of 40-60W, a distance of 10-15cm from the sample plane, and an irradiation time of 3-5min.
[0027] The fluorescent gel of this invention can be applied to anti-counterfeiting, information encryption, or flexible electronic devices.
[0028] Example 1: Step 1: Mix monomeric methacryloylethyl sulfobetaine and N-propene N'-2-hydroxyethyl thiourea at a molar ratio of 1:1, and add 30 wt% of deionized water. Heat and stir the mixture in a round-bottom flask at 70°C for 30 min to obtain a clear, pale yellow homogeneous solution of DES. Store the prepared DES in a vacuum desiccator containing silica gel for the next step.
[0029] Step 2: Guanine nucleoside, crosslinking agent polyethylene glycol diacrylate, and photoinitiator 2959 are added to the obtained polymerizable DES. The mixture is heated and stirred at 70°C for 15 minutes to obtain a pale yellow homogeneous prepolymer solution. The amount of guanine nucleoside added is controlled at 5 wt% of the total monomer mass, the amount of crosslinking agent added is controlled at 3 wt% of the total monomer mass, and the amount of photoinitiator added is controlled at 1 wt% of the total monomer mass.
[0030] Step 3: The obtained prepolymer solution is cast into a leveled polytetrafluoroethylene mold and polymerization is initiated under ultraviolet light irradiation to obtain a polyeutectic stimuli-responsive fluorescent gel, denoted as Co-PDES1-G. The ultraviolet light wavelength is 365nm, the power is 40W, the height of the ultraviolet light from the sample plane is 10cm, and the irradiation time is 5min.
[0031] Example 2: Step 1: Mix monomeric methacryloylethyl sulfobetaine and N-propene N'-2-hydroxyethyl thiourea at a molar ratio of 1.5:1, and add 30 wt% of deionized water. Heat and stir the mixture in a round-bottom flask at 70°C for 30 min to obtain a clear, pale yellow homogeneous solution of DES. Store the prepared DES in a vacuum desiccator containing silica gel for the next step.
[0032] Step 2: Guanine nucleoside, crosslinking agent polyethylene glycol diacrylate, and photoinitiator 2959 are added to the obtained polymerizable DES. The mixture is heated and stirred at 70°C for 15 minutes to obtain a pale yellow homogeneous prepolymer solution. The amount of guanine nucleoside added is controlled at 5 wt% of the total monomer mass, the amount of crosslinking agent added is controlled at 3 wt% of the total monomer mass, and the amount of photoinitiator added is controlled at 1 wt% of the total monomer mass.
[0033] Step 3: The obtained prepolymer solution is cast into a leveled polytetrafluoroethylene mold and polymerization is initiated under ultraviolet light to obtain a polyeutectic group-stimulated fluorescent gel, denoted as Co-PDES. 1.5-G. The ultraviolet lamp has a wavelength of 365nm, a power of 40W, is 10cm above the sample surface, and is irradiated for 5min.
[0034] Example 3: Step 1: Mix monomeric methacryloylethyl sulfobetaine and N-propene N'-2-hydroxyethyl thiourea at a molar ratio of 2:1, and add 30 wt% of deionized water. Heat and stir the mixture in a round-bottom flask at 70°C for 30 min to obtain a clear, pale yellow homogeneous solution of DES. Store the prepared DES in a vacuum desiccator containing silica gel for the next step.
[0035] Step 2: Guanine nucleoside, crosslinking agent polyethylene glycol diacrylate, and photoinitiator 2959 are added to the obtained polymerizable DES. The mixture is heated and stirred at 70°C for 15 minutes to obtain a pale yellow homogeneous prepolymer solution. The amount of guanine nucleoside added is controlled at 5 wt% of the total monomer mass, the amount of crosslinking agent added is controlled at 3 wt% of the total monomer mass, and the amount of photoinitiator added is controlled at 1 wt% of the total monomer mass.
[0036] Step 3: The obtained prepolymer solution is cast into a leveled polytetrafluoroethylene mold and polymerization is initiated under ultraviolet light irradiation to obtain a polyeutectic stimuli-responsive fluorescent gel, denoted as Co-PDES2-G. The ultraviolet light wavelength is 365nm, the power is 40W, the height of the ultraviolet light from the sample plane is 10cm, and the irradiation time is 5min.
[0037] Example 4: Step 1: Mix monomeric 2-(methacryloyloxy)-N,N,N-trimethylethylammonium methyl sulfate and N-propene N'-2-hydroxyethylthiourea at a molar ratio of 1.5:1, and add 40 wt% of deionized water. Heat and stir the mixture in a round-bottom flask at 70°C for 25 min to obtain a clear homogeneous DES solution. Store the prepared DES in a vacuum desiccator containing silica gel for further use.
[0038] Step 2: Guanine nucleoside, crosslinking agent N,N-methylenebisacrylamide, and photoinitiator 1-hydroxycyclohexylphenyl ketone are added to the obtained polymerizable DES. The mixture is heated and stirred at 80°C for 15 min to obtain a clear and transparent homogeneous prepolymer solution. The amount of guanine nucleoside added is controlled at 5 wt% of the total monomer mass, the amount of crosslinking agent added is controlled at 3 wt% of the total monomer mass, and the amount of photoinitiator added is controlled at 1 wt% of the total monomer mass.
[0039] Step 3: The obtained prepolymer solution is cast into a leveled polytetrafluoroethylene mold, and polymerization is initiated under ultraviolet light irradiation to obtain a polyeutectic stimuli-responsive fluorescent gel. The ultraviolet light wavelength is 365 nm, the power is 50 W, the height of the ultraviolet light from the sample plane is 15 cm, and the irradiation time is 5 min.
[0040] Example 5: Step 1: Mix monomeric methacryloyloxyethyltrimethylammonium chloride and N-propene N'-2-hydroxyethylthiourea at a molar ratio of 1.5:1, and add 20 wt% of deionized water. Heat and stir the mixture in a round-bottom flask at 60°C for 30 min to obtain a clear homogeneous DES solution. Store the prepared DES in a vacuum desiccator containing silica gel for the next step.
[0041] Step 2: Guanine nucleoside, crosslinking agent ethylene glycol dimethacrylate, and photoinitiator 2-hydroxy-2-methylphenylacetone are added to the obtained polymerizable DES. The mixture is heated and stirred at 75°C for 10 min to obtain a clear and transparent homogeneous prepolymer solution. The amount of guanine nucleoside added is controlled at 5 wt% of the total monomer mass, the amount of crosslinking agent added is controlled at 3 wt% of the total monomer mass, and the amount of photoinitiator added is controlled at 1 wt% of the total monomer mass.
[0042] Step 3: The obtained prepolymer solution is cast into a leveled polytetrafluoroethylene mold, and polymerization is initiated under ultraviolet light irradiation to obtain a polyeutectic stimuli-responsive fluorescent gel. The ultraviolet light wavelength is 365 nm, the power is 60 W, the height of the ultraviolet light from the sample plane is 12 cm, and the irradiation time is 3 min.
[0043] Example 6: Step 1: Mix monomeric (3-methacrylamidopropyl)trimethylammonium chloride and N-propenyne N'-2-hydroxyethylthiourea at a molar ratio of 1.5:1, and add 30 wt% of deionized water. Heat and stir the mixture in a round-bottom flask at 65°C for 30 min to obtain a clear homogeneous solution of DES. Store the prepared DES in a vacuum desiccator containing silica gel for the next step.
[0044] Step 2: Guanine nucleoside, crosslinking agent N,N-methylenebisacrylamide, and photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide are added to the obtained polymerizable DES. The mixture is heated and stirred at 80°C for 15 min to obtain a clear and transparent homogeneous prepolymer solution. The amount of guanine nucleoside added is controlled at 5 wt% of the total monomer mass, the amount of crosslinking agent added is controlled at 3 wt% of the total monomer mass, and the amount of photoinitiator added is controlled at 1 wt% of the total monomer mass.
[0045] Step 3: The obtained prepolymer solution is cast into a leveled polytetrafluoroethylene mold and polymerization is initiated under ultraviolet light irradiation to obtain a polyeutectic stimuli-responsive fluorescent gel. The ultraviolet light wavelength is 365 nm, the power is 50 W, the height of the ultraviolet light from the sample plane is 10 cm, and the irradiation time is 4 min.
[0046] Comparative Example 1: This comparative example is basically the same as Example 1, except that guanine nucleoside was not added in step 2, and the resulting fluorescent gel is denoted as Co-PDES1.
[0047] Comparative Example 2: This comparative example is basically the same as Example 2, except that guanine nucleoside was not added in step 2, and the resulting fluorescent gel is denoted as Co-PDES. 1.5 .
[0048] Comparative Example 3: This comparative example is basically the same as Example 3, except that guanine nucleoside was not added in step 2, and the resulting fluorescent gel is denoted as Co-PDES2.
[0049] The gels prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests: (1) Fourier transform infrared spectroscopy test: The infrared spectrum of the sample was tested using a Fourier transform infrared spectrometer (Thermo Scientific Nicoleti S20); the wavenumber scan range was 400-4000 cm⁻¹. -1 Set the resolution to 4cm -1 The ambient temperature during the test was 25℃, and the relative humidity was 30%–35%.
[0050] (2) Thermal performance test: The melting point of the eutectic solvent and the glass transition temperature of the resulting fluorescent gel were determined using a DSC 200F3 differential scanning calorimeter (NETZS Instruments GmbH, Germany). The test atmosphere was nitrogen atmosphere, the heating and cooling rate was 10℃ / min, and the total temperature test range was -80℃ to 100℃.
[0051] (3) Mechanical performance testing: using AI 7000 The mechanical properties of the obtained polyeutectic stimuli-responsive fluorescent gel were tested using an NGD-type electronic universal testing machine (Gatewell (Dongguan) Co., Ltd.). The sample size was cut into dumbbell shape according to national standards, and the tensile loading speed was 50 mm / min. The test environment temperature was 25℃, and the relative humidity was maintained at 30%~35%.
[0052] (4) Fluorescence performance test: The emission spectra of the obtained polyeutectic stimuli-responsive fluorescent gel at different excitation wavelengths were tested using a Quanta Master 8000 fluorescence spectrometer (Horiba (China) Trading Co., Ltd.).
[0053] (5) Metal ion response test: Prepare Fe with the same concentration 2+ K + Fe 3+ Cu 2+ Co 2+ Ni 2+ Zn 2+ Cd 2+ Mg 2+ The obtained polyeutectic stimuli-responsive fluorescent gel was cut into circular samples of the same size and immersed in a metal ion solution for 3 hours. The fluorescence effect of the samples before and after immersion was observed.
[0054] (6) Strain sensing performance test: The changes in electrical signals of the gel during the movement of different parts of the human body were measured using an electrochemical workstation (CHI660E). Measurements were performed in t-mode. The ambient temperature was 25℃, and the relative humidity was 30%–35%.
[0055] To demonstrate the successful preparation of DES, Fourier transform infrared spectroscopy was used to characterize and analyze the DES obtained in Example 2. The results are as follows: Figure 1 As shown in the figure, the DES curve ranges from 3650 to 2800 cm⁻¹. -1 The appearance of this band indicates a large, broad peak signifying hydrogen bonding, and it is located at 1303 cm⁻¹ in the SBMA curve. -1 1192cm -1 Place and -SO 3- Stretching vibration of S=O, 1042cm -1 The characteristic peaks related to SO stretching vibrations are weakened in the DES curve and redshifted to 1295 cm⁻¹. -1 1158cm -1 1034cm -1 The characteristic peak associated with C=O stretching vibrations is from 1723 cm⁻¹. -1 Redshifted to 1718cm -1 The location is at 1522cm on the AHETU curve. -1 The characteristic peak related to the tensile vibration of the C=S bond is blue-shifted to 1553 cm⁻¹ in the DES curve due to the increase in the force constant of C=S during hydrogen bonding. -1 Furthermore, no new characteristic peaks appeared throughout the entire process.
[0056] Figure 2The differential scanning calorimetry (DSC) curve of the DES prepared in Example 2 shows that the lowest eutectic point of DES is -47.88°C, which is much lower than the melting point of methacryloyl ethyl sulfobetaine (150°C) and the melting point of N-propene N'-2-hydroxyethyl thiourea (78°C), providing direct proof of the successful preparation of DES.
[0057] To demonstrate the successful polymerization of the fluorescent gel and the introduction of guanine nucleoside (G), FT-IR was used to analyze the Co-PDES obtained in Example 2. 1.5 The chemical structure of the -G fluorescent gel was characterized, and the results are as follows: Figure 3 As shown, after in-situ photopolymerization, the Co-PDES curve at 1636 cm⁻¹... -1 The peaks related to C=C stretching vibrations at the Co-PDES curve are weaker than those in the DES curve, indicating that the double bonds have undergone polymerization. After adding hydrogen bond density modifier G, Co-PDES... 1.5 The -G curve appears at 1296cm. -1 The presence of characteristic peaks related to the stretching vibrations of the CN bonds in the purine ring skeleton confirms the successful introduction of G; simultaneously, the stretching vibration peak attributable to C=O in G increases from 1731 cm⁻¹. -1 Redshift to Co-PDES 1.5 1716cm in the -G curve -1 Location; 1476cm in Co-PDES -1 Place and -CN + - The peak related to stretching vibrations has redshifted to 1473 cm⁻¹ -1 All of the above indicate that the gel successfully polymerized and formed a high-density hydrogen bond network.
[0058] In addition, Co-PDES were measured in the range of -80℃ to 100℃ using DSC. 1.5 The thermal behavior of the -G gel, as shown in the results Figure 4 As shown, no obvious melting and crystallization peak appears in the DSC curve, and its glass transition temperature is -24.71℃, proving that Co-PDES... 1.5 -G gel has an amorphous structure and good low-temperature resistance.
[0059] The mechanical properties of the gels obtained in Examples 1-3 and Comparative Examples 1-3 were tested using a universal testing machine, and the resulting stress-strain curves are shown below. Figure 5 As shown, it can be seen that, at the same molar ratio, the addition of guanine nucleoside caused the gels of the corresponding examples to exhibit higher stress and strain than the comparative gels, thus playing a role in toughening and strengthening. As shown in the figure, Co-PDES 1.5 -G strain from Co-PDES 1.5The strain of guanine increased from 530% to 715%, and the stress increased from 0.8 MPa to 0.96 MPa; the strain of Co-PDES2-G increased from 415% to 493%, and the stress increased from 0.95 MPa to 1.1 MPa. This is due to the multiple hydrogen bonds formed by the interaction between guanine nucleoside and the eutectic solvent, which enhances the hydrogen bond density inside the gel when forming the polymer network, thus resulting in an increase in the mechanical strength of the gel. The method of this invention selects AHETU as a hydrogen bond donor. This hydrogen bond donor structure can conjugate with molecules within the gel network and undergo charge transfer, imparting excellent intrinsic fluorescence properties to the gel while further avoiding the influence of external fluorescent filler doping and filler color on the gel's optical transmittance. Figure 6 The fluorescent gels prepared in the examples all have an optical transmittance of over 70% in the visible light range.
[0060] The polyeutectic stimuli-responsive fluorescent gel of this invention exhibits excellent self-healing and conductivity. For example... Figure 7 As shown, a complete Co-PDES block 1.5 -G gel, when cut in the middle and re-exposed at room temperature for a period of time, showed that the fractured interface was basically healed in about 1 hour and did not break under 50% deformation.
[0061] To further observe the self-healing effect of the gel, changes in the gel incision were recorded using an optical microscope over 60 minutes. The results are as follows: Figure 8 As shown, the gel exhibited a healing trend at 30 min, and the fracture interface almost disappeared at 60 min.
[0062] Furthermore, the electro-healing efficiency of the gel was further evaluated. Figure 9 As shown, the Co-PDES prepared in Example 2 1.5 The -G gel was cut with a blade and connected in series with the circuit. The LED bulb lit up immediately after the two cut surfaces touched, indicating that the circuit connection was successful. This is due to Co-PDES. 1.5 The presence of numerous dynamic non-covalent bonds within the -G gel enables rapid reconnection of conductive channels at the fracture interfaces. To accurately measure the electro-self-healing rate, the current was tracked in real-time using the it mode of an electrochemical workstation. The results showed that once the two fracture interfaces came into contact, Co-PDES... 1.5 -G gel can rapidly recover from 0A to the original current signal within 0.4s, and there is no significant difference in current recovery time after 5 cycles. Figure 10 This further demonstrates the gel's excellent self-healing efficiency.
[0063] To further quantify Co-PDES XThe conductivity of Co-PDES1-G and Co-PDES-G gels was determined using electrochemical impedance spectroscopy (EIS) to record the conductivity at room temperature. 1.5 The impedance of -G, Co-PDES2-G gel ( Figure 11 a), and the change in the conductivity of the gel was obtained by calculation ( Figure 11 (b) The results showed that the conductivity decreased with the increase of SBMA content in the system.
[0064] The polyeutectic stimuli-responsive fluorescent gel prepared in this invention can be used as a flexible electronic device and has potential application value in the field of human motion monitoring. For example... Figure 12 As shown, combined with an electrochemical workstation, finger flexion, wrist flexion, mouth closure, elbow flexion, knee flexion, leg raising, and neck flexion (in order) can be monitored. Figure 12 The real-time electrical signal changes of human body parts such as ag (bending amplitude) can be observed intuitively under different bending amplitudes, and the changes of ΔR / R0 can be distinguished well.
[0065] The gel prepared in this invention exhibits intrinsic fluorescence properties. The selected hydrogen bond donor, N-propene N'-2-hydroxyethylthiourea, imparts fluorescence to the gel while forming a eutectic solvent. Therefore, to further understand the fluorescence properties of the obtained gel, its emission spectra at different excitation wavelengths were measured using a fluorescence spectrometer. The results are as follows: Figure 13 As shown, the emission spectrum exhibits a redshift with changing excitation wavelength, reaching its maximum fluorescence intensity at an excitation wavelength of 400 nm. Based on this fluorescence characteristic, a "flower" gel was polymerized using the prepolymer solution from Example 2, and its feasibility as a fluorescent anti-counterfeiting ink was verified through screen printing. Figure 14 Under sunlight, the "flower" gel appears pale yellow, and the printed pattern on paper is almost invisible. Under ultraviolet light, both the "flower" gel and the printed pattern exhibit bright blue fluorescence.
[0066] Furthermore, this invention investigated the stimulus-response characteristics of the prepared polyeutectic stimuli-responsive fluorescent gel to different metal ions. For example... Figure 15 As shown, at the same concentration (2000 mg / L), different Fe 2+ K + Fe 3+ Cu 2+ Co 2+ Ni 2+ Zn 2+ Cd 2+ Mg 2+ The fluorescence effect image after immersion in solution shows that the gel reacts with Fe. 2+ Fe 3+ Cu2+ It exhibits a relatively obvious fluorescence quenching effect. Figure 15 (i-ii). Then, select Cu. 2+ The solution further investigated the gel at different concentrations of Cu. 2+ Fluorescence quenching effect ( ) Figure 15 iii-iv), with Cu 2+ The fluorescence quenching effect becomes more pronounced with increasing solution concentration. Further quantification of Cu using fluorescence spectroscopy was performed. 2+ The effect of solution concentration on fluorescence intensity, such as Figure 16 As shown, the gel fluorescence intensity varies with Cu 2+ The concentration increases with a linear decreasing trend, and... Figure 15 The results presented by iv are consistent.
[0067] Based on this gel, Cu 2+ The fluorescence quenching properties of the prepolymer solution demonstrate its preliminary application as a fluorescent ink in the erasure of anti-counterfeiting information. Figure 17 As shown, the phrase "Realizing the past cannot be changed, but knowing the future can be pursued" was screen-printed onto paper. The text is almost invisible in sunlight but displays a clear blue color under ultraviolet light. Subsequently, 0.5M Cu... 2+ The solution covered the words "Knowing the future is within reach" and after air drying, only the words "Realizing the past cannot be changed, but knowing the future is within reach" appeared under ultraviolet light.
Claims
1. A method for preparing a poly-eutectic based stimuli-responsive fluorescent gel, characterized in that, The method is implemented according to the following steps: Step 1, mixing monomeric hydrogen bond acceptor and N-propenyl-N'-2-hydroxyethyl thiourea to obtain mixture A, adding deionized water to mixture A to obtain mixture B, and heating and stirring mixture B to obtain polymerizable deep eutectic solvent; Step 2, adding guanosine, photoinitiator and crosslinking agent to the polymerizable deep eutectic solvent prepared in step 1, and heating and stirring to obtain pre-polymerization solution; Step 3, casting the pre-polymerization solution prepared in step 2 in a mold, and initiating polymerization under irradiation of ultraviolet lamp to obtain polydeep eutectic stimulus-responsive fluorescent gel.
2. The method for preparing the polyeutectic stimuli-responsive fluorescent gel according to claim 1, characterized in that, In step 1, the molar ratio of monomeric hydrogen bond acceptor and N-propenyl-N'-2-hydroxyethyl thiourea is 1-2:1, and the mass of deionized water is 20-40wt% of the mass of mixture A.
3. The method for preparing the polyeutectic group stimulus-responsive fluorescent gel according to claim 1, characterized in that, In step 1, the monomeric hydrogen bond acceptor is a mixture of one or more of methacryloyl ethyl sulfobetaine, methacryloyloxyethyl trimethyl ammonium chloride, (3-methacrylamidopropyl) trimethyl ammonium chloride, 2-(methacryloyloxy)-N,N,N-trimethyl ethyl ammonium methyl sulfate or N-(2-carboxyethyl)-N,N-dimethylaminoethyl methacrylate inner salt.
4. The method for preparing the polyeutectic group stimulus-responsive fluorescent gel according to claim 1, characterized in that, In step 1, mixture B is heated and stirred at 60-70℃ for 20-30min.
5. The method for preparing the polyeutectic stimuli-responsive fluorescent gel according to claim 1, characterized in that, In step 2, the photoinitiator is a mixture of one or more of photoinitiator 2959, 2-hydroxy-2-methylphenylpropanone, 1-hydroxycyclohexyl phenyl ketone or 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide; The crosslinking agent is a mixture of one or more of polyethylene glycol diacrylate, N,N-methylene bisacrylamide or ethylene glycol dimethyl acrylate.
6. The method for preparing the polyeutectic group stimulus-responsive fluorescent gel according to claim 1, characterized in that, In step 2, the addition amount of the photoinitiator is 1wt% of the mass of mixture A, the addition amount of the crosslinking agent is 3wt% of the mass of mixture A, and the addition amount of guanosine is 5wt% of the mass of mixture A.
7. The method for preparing the polyeutectic group stimulus-responsive fluorescent gel according to claim 1, characterized in that, In step 2, heating and stirring is carried out at 70-80℃ for 10-15min.
8. The method for preparing the polyeutectic stimuli-responsive fluorescent gel according to claim 1, characterized in that, In step 3, the irradiation parameters of the ultraviolet lamp are as follows: The wavelength of the ultraviolet lamp is 365nm, the power is 40-60W, the distance between the ultraviolet lamp and the sample plane is 10-15cm, and the irradiation time is 3-5min.
9. A polydeep eutectic-based stimuli-responsive fluorescent gel, characterized in that, The polydeep eutectic stimulus-responsive fluorescent gel is prepared by the method of any one of claims 1-8.
10. The polydeep eutectic-based stimuli-responsive fluorescent gel according to any one of claims 1 to 9, wherein, The polydeep eutectic stimulus-responsive fluorescent gel is applied in the fields of anti-counterfeiting, information encryption or flexible electronic devices.