A reversible humidity-responsive fluorescent color-changing system, preparation method thereof and application thereof

Abstract

The present invention provides a method for preparing a reversible humidity-responsive fluorescent color-changing system, comprising the following steps: A) mixing anionic polyelectrolytes, fluorescent molecules and water to obtain an electrospinning aqueous solution; B) electrospinning the electrospinning aqueous solution, arranging a mask at the receiving end to draw a first fluorescent pattern, and obtaining an electrospinning film having a first fluorescent pattern; C) drawing a second anti-counterfeiting pattern on the surface of the electrospinning film obtained in step B) using a waterproof coating to obtain a reversible humidity-responsive fluorescent color-changing system. The present application also provides a reversible humidity-responsive fluorescent color-changing system and its application. The reversible humidity-responsive fluorescent color-changing system provided by the present invention has a dual anti-counterfeiting function of fluorescence, presents a first pattern under ultraviolet light, and presents a second pattern when the humidity rises (such as breathing), which greatly improves the anti-counterfeiting performance of the fluorescent pattern; and it has specificity for water and reversible rapid humidity-responsive color change with fluorescent color change.

Description

Technical Field

[0001] The present invention relates to the field of anti-counterfeiting technology, and in particular to a reversible humidity-responsive fluorescent color-changing system, a preparation method thereof and applications thereof. Background Art

[0002] Humidity measurement is closely related to human life. After many technological iterations, semiconductor humidity sensors have stood out for their advantages of accurate measurement and easy integration. However, semiconductor sensors have the problems of complex manufacturing, heavy weight, and inability to withstand electromagnetic interference. With people's demand for intelligent devices, people have a demand for visual humidity sensors that provide perceptual cognition.

[0003] Existing humidity-color responsive materials include water-based color-changing dyes, inorganic nanocrystals, and structural color materials. However, the synthesis process of water-based color-changing dyes is long, the chemical stability of inorganic nanocrystals is poor, and the preparation of photonic crystal materials is complex. Organic fluorescent colors are bright and stable, and it would be a great improvement if they were used in humidity-color responsive materials.

[0004] In addition, with the development of economy and society, counterfeit and shoddy products have become increasingly difficult to prevent as the technical threshold has been lowered. Therefore, anti-counterfeiting technology is particularly important and needs to be continuously updated. Most of the current fluorescent anti-counterfeiting methods rely on one or several specific color emission wavelengths to present encrypted patterns. Most of the existing fluorescent pattern anti-counterfeiting technologies target a certain fluorescent substance, which is excited by ultraviolet light and emits fluorescence of a specific color for anti-counterfeiting pattern design. There are also a few that use fluorescent units with stimulus response to achieve the appearance / disappearance or change of fluorescent patterns. These anti-counterfeiting modes are relatively simple and easy to imitate. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a reversible humidity-responsive fluorescent color-changing system and a preparation method thereof. The reversible humidity-responsive fluorescent color-changing system provided in the present application can observe a first anti-counterfeiting pattern through an ultraviolet lamp, and a second anti-counterfeiting pattern can be observed under humidity changes.

[0006] The present application provides a method for preparing a reversible humidity-responsive fluorescent color-changing system, comprising the following steps:

[0007] A) mixing anionic polyelectrolytes, fluorescent molecules and water to obtain an electrospinning aqueous solution; the fluorescent molecules are fluorescent molecules that change color after receiving protons;

[0008] B) electrospinning the electrospinning aqueous solution, arranging a mask at a receiving end to draw a first fluorescent pattern, and obtaining an electrospinning film having the first fluorescent pattern;

[0009] C) Drawing a second anti-counterfeiting pattern on the surface of the electrospun film obtained in step B) using a waterproof coating to obtain a reversible humidity-responsive fluorescent color-changing system.

[0010] Preferably, the anionic polyelectrolyte is polyacrylic acid, polymethacrylic acid or poly(2-acrylamide-2-methylpropanesulfonic acid); the fluorescent molecule is a compound having an amino group, an imino group or a pyridine group directly connected to a conjugated skeleton, specifically, the fluorescent molecule is selected from tetrakis(4-pyridylbiphenyl)ethylene, tetrakis(4-pyridylvinylphenyl)ethylene or (2Z,2'Z)-2,2'-((1,4-phenylene)bis(3-(4-pyridylphenyl)acrylonitrile); the waterproof coating comprises a waterproof material and a solvent, and the waterproof material is selected from one or more of paraffin, polymethacrylic acid, polyethylene wax, polystyrene, polyvinyl fluoride and vaseline; the mass ratio of the anionic polyelectrolyte to the fluorescent molecule is (500-1000):1.

[0011] Preferably, the electrospinning step is specifically as follows:

[0012] The electrospinning aqueous solution is sucked into the syringe, and the syringe is transferred to the electrospinning injection device, and the injection parameters are adjusted; aluminum foil is coated on the receiving roller, the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply; a mask is arranged at the receiving end, the receiving end rolling device and the transmitting end translation mode are turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value, and then the injection pump is turned on and the transmitting end power supply is gradually adjusted to the required voltage to obtain an electrospinning film with a first fluorescent pattern.

[0013] Preferably, the voltage of the electrospinning is 10 to 20 kV, the voltage at the receiving end is -1.5 kV to -2.5 kV, the distance from the receiving end is 15 to 20 cm, and the spinning speed is 8 to 15 μm·min -1 ; The concentration of the electrospinning aqueous solution is 5 to 15 wt%.

[0014] Preferably, the diameter of the spinning fibers in the electrospun film is 200 to 300 nm.

[0015] Preferably, step C) is specifically:

[0016] Mixing a waterproof material and an organic solvent to obtain a waterproof coating; the waterproof material is selected from one or more of paraffin wax, polymethacrylic acid, polyethylene wax, polystyrene, polyvinyl fluoride and vaseline;

[0017] The target pattern is transferred onto the surface of the electrostatically spun film by using a mask method or a stencil printing method with a waterproof coating, and the electrostatically spun film after the transfer pattern is dried to obtain a reversible color-changing fluorescent dual anti-counterfeiting pattern.

[0018] Preferably, the electrospinning aqueous solution further comprises an auxiliary polymer, and the auxiliary polymer is selected from one or more of polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene glycol.

[0019] The present application also provides a reversible humidity-responsive fluorescent color-changing system, which consists of an electrospun film having a first fluorescent pattern and a second anti-counterfeiting pattern composited on the surface of the first fluorescent pattern, wherein the electrospun film includes anionic polyelectrolytes and fluorescent molecules, wherein the fluorescent molecules change color after receiving protons, and the second anti-counterfeiting pattern is drawn by a waterproof coating.

[0020] Preferably, the electrospun film further comprises an auxiliary polymer, and the auxiliary polymer is selected from one or more of polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene glycol.

[0021] The present application also applies for a reversible humidity-responsive fluorescent color-changing system prepared by the preparation method or the application of the reversible humidity-responsive fluorescent color-changing system in the field of anti-counterfeiting.

[0022] The present application provides a reversible humidity-responsive fluorescent color-changing system, which is composed of a substrate, an electrospun film with a first fluorescent pattern composited on the surface of the substrate, and a waterproof layer with an anti-counterfeiting pattern composited on the surface of the first fluorescent pattern, wherein the electrospun film includes an anionic polyelectrolyte and a fluorescent molecule, wherein the fluorescent molecule is a fluorescent molecule that changes color after receiving a proton. The reversible humidity-responsive fluorescent color-changing system provided by the present application constructs a stimulus-responsive system with the aid of fluorescent molecules and a polymer substrate, and has no pattern under visible light. Due to the presence of fluorescent molecules, the system presents a first fluorescent pattern under ultraviolet light, and in the case of humidity changes, the anionic polyelectrolyte ionizes to produce protons, and the fluorescent molecules receive protons to change color, thereby realizing the appearance of a second fluorescent pattern under humidity changes. Further, the reversible humidity-responsive fluorescent color-changing system provided by the present application is prepared by electrospinning, which can achieve rapid humidity response, and at the same time, the fluorescent color-changing system has a specific response to water and strong resistance to interference from organic solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a scanning electron microscope photograph of the electrospun fiber film prepared in Example 1 ( Figure 1 a) and fiber distribution ( Figure 1 b);

[0024] Figure 2 This is a comparison diagram of infrared spectra of the electrospun fiber film prepared in Example 1 in dry and humid environments;

[0025] Figure 3The changes in fluorescence color and fluorescence intensity of the electrospun fiber film prepared in Example 1 in different humidity environments;

[0026] Figure 4 The fluorescence spectrum of the electrospun fiber film prepared in Example 1 in a dry-humid environment cycle;

[0027] Figure 5 The fluorescence spectra of the electrospun fiber film prepared in Example 1 in different solvent fumigations;

[0028] Figure 6 This is a graph showing the current variation of the electrospun fiber film prepared in Example 1 under constant voltage conditions;

[0029] Figure 7 These are fluorescent photographs of the first fluorescent pattern drawn by electrospinning prepared in Example 1 and the second fluorescent pattern obtained after anti-counterfeiting pattern transfer under visible light and ultraviolet light. DETAILED DESCRIPTION

[0030] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0031] In response to the problems with humidity and anti-counterfeiting, the present application provides a reversible humidity-responsive fluorescent color-changing system, which will undergo a red shift in fluorescence as humidity rises, thereby achieving visual sensing of humidity. It has a dual anti-counterfeiting function of fluorescence, presenting a first pattern under ultraviolet light and a second pattern when humidity rises (such as breathing), greatly improving the anti-counterfeiting performance of the fluorescent pattern; and it has specificity for water and reversible rapid humidity-responsive color change in fluorescence color change. Specifically, the present application first provides a method for preparing a reversible humidity-responsive fluorescent color-changing system, which mixes anionic polyelectrolytes and fluorescent molecules to obtain an electrospinning aqueous solution, and then uses electrospinning technology to prepare a first fluorescent pattern; a waterproof layer is transferred onto the fluorescent pattern using a mask method or a stencil printing method to achieve the drawing of a second anti-counterfeiting pattern, further improving the anti-counterfeiting performance of the fluorescent anti-counterfeiting fiber, thereby achieving a reversible conversion of fluorescence-humidity color change. Specifically, an embodiment of the present invention discloses a method for preparing a reversible humidity-responsive fluorescent color-changing system, comprising the following steps:

[0032] A) mixing anionic polyelectrolytes, fluorescent molecules and water to obtain an electrospinning aqueous solution; the fluorescent molecules are fluorescent molecules that change color after receiving protons;

[0033] B) electrospinning the electrospinning aqueous solution, arranging a mask at a receiving end to draw a first fluorescent pattern, and obtaining an electrospinning film having the first fluorescent pattern;

[0034] C) Drawing a second anti-counterfeiting pattern on the surface of the electrospun film obtained in step B) using a waterproof coating to obtain a reversible humidity-responsive fluorescent color-changing system.

[0035] In the process of preparing a reversible humidity-responsive fluorescent color-changing system, the present application first mixes anionic polyelectrolytes, fluorescent molecules and water to obtain an electrospinning aqueous solution. In the present application, the anionic polyelectrolyte is a commercially available product or a product prepared by a method well known to those skilled in the art, including but not limited to one or more copolymerization or monomerization of acrylic acid, methacrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid, and is purified by dialysis to make the molecular weight distribution relatively narrow, which is beneficial to the subsequent related spinning steps; specifically, the anionic polyelectrolyte is selected from polyacrylic acid, polymethacrylic acid or poly (2-acrylamide-2-methylpropanesulfonic acid). The fluorescent molecule is a fluorescent molecule whose color changes after accepting a proton, that is, the fluorescent molecule is a compound directly connected to an amino group, an imino group, a pyridyl group, a pyrrolyl group, a thiazolyl group, an imidazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a pyrrolyl group, a quinolyl group, etc. on its conjugated skeleton, which can accept proton transfer or undergo a ring-opening / cyclization reaction under proton catalysis, and thus cause a change in LUMO / HOMO energy level to change the fluorescence color. More specifically, the fluorescent molecule is selected from tetrakis(4-pyridylbiphenyl)ethylene, tetrakis(4-pyridylvinylphenyl)ethylene or (2Z,2'Z)-2,2'-((1,4-phenylene)bis(3-(4-pyridylphenyl)acrylonitrile); the fluorescent molecule is a commercially available product or prepared according to a method well known to those skilled in the art. In the present application, the anionic polyelectrolyte is used to provide a polymer skeleton, and at the same time, it can provide an acidic environment when it meets water, so that the fluorescent molecule can achieve fluorescence color change. Therefore, the presence of the anionic polyelectrolyte and the fluorescent molecule can achieve fluorescence-humidity conversion.

[0036] In the electrospinning aqueous solution, the mass ratio of the anionic polyelectrolyte to the fluorescent molecule is (500-1000):1, specifically, the mass ratio of the anionic polyelectrolyte to the fluorescent molecule is (700-900):1; the concentration of the electrospinning aqueous solution is 5-15wt%, more specifically, the concentration of the electrospinning aqueous solution is 7-10wt%. In the present application, the electrospinning aqueous solution also includes an auxiliary polymer, which has good water solubility and good fiber-forming and supporting properties to assist the preparation of electrospinning films by electrospinning anionic polyelectrolytes that are not easy to achieve; specifically, the auxiliary polymer is selected from one or more of polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene glycol.

[0037] The present application then electrospins the electrospinning aqueous solution, during which a mask is arranged at the receiving end to draw a first fluorescent pattern, thereby obtaining an electrospinning film having a first fluorescent pattern; the electrospinning process is specifically as follows:

[0038] The electrospinning aqueous solution is sucked into the syringe, and the syringe is transferred to the electrospinning injection device, and the injection parameters are adjusted; aluminum foil is coated on the receiving roller, the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply; a mask is arranged at the receiving end, the receiving end rolling device and the transmitting end translation device are turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value, and then the injection pump is turned on and the transmitting end power supply is gradually adjusted to the required voltage to obtain an electrospinning film with a first fluorescent pattern.

[0039] The electrospinning described in this application is a method well known in the art, but the electrospinning used in this application can achieve a large specific surface area of ​​electrospinning that responds quickly to light and humidity. In the electrospinning process, an electrospinning needle with an inner diameter of 1 mm is used, and aluminum foil is preferably used at the receiving end; the electrospinning voltage is 10 to 20 kV, the receiving end voltage is -1.5 kV to -2.5 kV, the receiving end distance is 15 to 20 cm, and the spinning speed is 8 to 15 μm·min -1 ; The concentration of the electrospinning aqueous solution is 5 to 15 wt%.

[0040] After the above electrospinning and mask setting, an electrospinning film with a first fluorescent pattern is prepared; wherein the first fluorescent pattern can be arbitrarily set according to requirements, and corresponds to the pattern of the mask.

[0041] According to the present invention, a second anti-counterfeiting pattern is then drawn on the surface of the electrospun film to obtain a reversible humidity-responsive fluorescent color-changing system. In the present application, the second anti-counterfeiting pattern is prepared by a waterproof coating, which can achieve a pattern of a specific shape to maintain the fluorescence of the original dry state. The above process is specifically as follows:

[0042] Mixing waterproof material and organic solvent to obtain waterproof coating;

[0043] The target pattern is transferred onto the surface of the electrostatically spun film by using a mask method or a stencil printing method with a waterproof coating, and the electrostatically spun film after the transfer pattern is dried to obtain a reversible color-changing fluorescent dual anti-counterfeiting pattern.

[0044] In the above process, the waterproof material is well known to those skilled in the art. For example, the waterproof material is selected from one or more of paraffin, polymethacrylic acid, polyethylene wax, polystyrene, polyvinyl fluoride and vaseline; the organic solvent is well known to those skilled in the art. For example, the organic solvent is selected from ether, acetone, n-hexane, toluene, ethyl acetate, cyclohexane, decahydronaphthalene, dichloromethane, chloroform and the like. The transfer method is carried out in a manner well known to those skilled in the art, and there is no particular limitation in this application. The drying temperature is 25 to 60°C to ensure that the waterproof layer is more compact.

[0045] The present application also provides a reversible humidity-responsive fluorescent color-changing system prepared by the above method, which is composed of an electrospun film having a first fluorescent pattern and a second anti-counterfeiting pattern composited on the surface of the first fluorescent pattern, wherein the electrospun film includes anionic polyelectrolytes and fluorescent molecules, wherein the fluorescent molecules are fluorescent molecules that change color after accepting protons, and the second anti-counterfeiting pattern is drawn by a waterproof coating.

[0046] For the humidity-responsive fluorescent color-changing system provided in the present application, the first fluorescent anti-counterfeiting pattern and the second fluorescent humidity-responsive anti-counterfeiting pattern therein can be arbitrarily set according to needs, and the present application has no special restrictions on this.

[0047] The present application also provides the application of the above-mentioned reversible humidity-responsive fluorescent color-changing system in the field of anti-counterfeiting.

[0048] The reversible humidity-responsive fluorescent color-changing system provided in the present application constructs a stimulus-responsive system with the help of fluorescent molecules and polymer substrates, and can be secondary encrypted on the basis of the original fluorescent pattern. There is no pattern under low-humidity visible light, and a first fluorescent pattern is presented under ultraviolet light. The second fluorescent pattern can be observed after local humidity increase. The reversible humidity-responsive fluorescent color-changing system provided in the present application has specificity for water and reversible rapid humidity-responsive color change of fluorescent color change. This design further enhances the complexity, safety and convenience of the fluorescent anti-counterfeiting pattern. This stimulus-responsive fluorescent multiple anti-counterfeiting is of pioneering significance and has a positive role in promoting the upgrading of fluorescent anti-counterfeiting technology.

[0049] In order to further understand the present invention, the reversible humidity-responsive fluorescent color-changing system, its preparation method and application provided by the present invention are described below in combination with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0050] Example 1

[0051] A method for preparing reversible color-changing fluorescent dual anti-counterfeiting fiber comprises the following steps:

[0052] 1) Preparation of polymer substrate polyacrylic acid

[0053] ①Weighing and dissolving drugs

[0054] Weigh 1.000 g ± 0.001 g of acrylic acid and 0.040 g ± 0.001 g of ammonium persulfate, add them to 4 ml of deionized water and shake until fully dissolved;

[0055] ②Synthesis and purification of polymer polyacrylic acid

[0056] The above solution was bubbling with nitrogen to remove oxygen in the solution, and the solution was kept at 60° C. in a nitrogen atmosphere for 6 hours. After the above reaction was completed, the solution after the reaction was injected into a dialysis bag with a pore size of 3000 and sealed, and the dialysis bag was placed in deionized water for dialysis to remove residual initiators, monomers and other impurities; the dialysis process was carried out for three days, and the deionized water was replaced every 24 hours. After the dialysis was completed, freeze-drying was performed to obtain purified polyacrylic acid powder, which was vacuum dried and stored;

[0057] 2) Preparation of humidity-responsive fluorescent fibers by electrospinning

[0058] ①Weighing and dissolving drugs

[0059] Weigh 0.800 g ± 0.001 g of the above-synthesized and purified polyacrylic acid and 0.002 g ± 0.0001 g of tetrapyridyltetraphenylethylene, add them into 9.2 g of deionized water, and stir them slowly for three days to obtain an electrospinning aqueous solution with a solid content of 8 wt%;

[0060] ②Electrospinning

[0061] The electrospinning process used an electrospinning needle with an inner diameter of 1 mm, an aluminum foil at the receiving end, an electrospinning voltage of 15 kV, and a receiving end voltage of -2 kV; a receiving distance of 18 cm, and a spinning speed of 10 μL·min -1 ; During the electrospinning process, a mask can be arranged at the receiving end to achieve the drawing of the first fluorescent pattern;

[0062] First, the electrospinning aqueous solution is sucked into the syringe, and the bubbles therein are removed, and the syringe is transferred to the electrospinning injection device, and the injection parameters are adjusted; the aluminum foil is coated on the receiving roller, flattened and dusted, and then the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply; a mask is arranged at the receiving end, the receiving end rolling device and the transmitting end translation device are turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value, and then the injection pump is turned on and the transmitting end power supply is gradually adjusted to the required voltage, and the electrospinning film described above can be obtained on the aluminum foil at the receiving end;

[0063] 3) Drawing of the second anti-counterfeiting pattern

[0064] ①Weighing and dissolving drugs

[0065] Weigh 0.500 g ± 0.001 g of paraffin wax and dissolve it in 20 ml of ether to prepare a hydrophobic coating;

[0066] ② Pattern transfer

[0067] The target pattern is transferred onto the prepared electrospun film using a mask method or a stencil printing method. After the ether evaporates naturally, the electrospun film with the transferred pattern is placed in a vacuum drying oven at 50°C for two hours to make the hydrophobic pattern dense, thereby obtaining an electrospun film with a double pattern.

[0068] 4) detection, analysis and characterization; specifically:

[0069] The morphology, fluorescence properties, reaction of the fluorescence color change process, and response speed of the fluorescence color change of the prepared electrospun film with double patterns are detected, analyzed, and characterized;

[0070] The morphology of electrospun films was analyzed using scanning electron microscopy;

[0071] Functional group analysis of electrospun films was performed using Fourier transform infrared spectroscopy;

[0072] The fluorescence performance of the electrospun films was analyzed by using an ultraviolet fluorescence spectrophotometer, including fluorescence spectrum, fluorescence stimulus response performance, fluorescence color change repeatability, and selectivity.

[0073] The color change response speed of the electrospun film was analyzed using an electrochemical workstation.

[0074] Figure 1 This is a scanning electron microscope photo of the electrospun fiber film prepared in Example 1 ( Figure 1 a) and fiber distribution ( Figure 1 b); As can be seen from the figure, the spun fibers are relatively uniform, with a diameter of about 200nm, a smooth and randomly distributed fiber surface, and micropores formed by overlapping fibers that can achieve rapid circulation of water molecules and achieve rapid humidity response.

[0075] Figure 2 This is a comparison of infrared spectra of the electrospun fiber film with double patterns prepared in Example 1 in dry and wet environments; it can be seen from the figure that the film can absorb water in a wet environment, and the polyacrylic acid substrate is rapidly ionized to generate H + From the corresponding FT-IR spectrum, we can see that the C=O stretching vibration signal is from 1710 cm-1 of COOH to -1 The signal becomes COO - 1635cm -1 signal, and tetrapyridyltetraphenylethylene is protonated to form 4H-TPE-4Py 4+ , achieving water-induced fluorescence color change.

[0076] Figure 3 The changes in fluorescence color and fluorescence intensity of the electrospun fiber film prepared in Example 1 in different humidity environments. As can be seen from the figure, the fluorescence color shows obvious changes in different relative humidity environments, which enables the film to produce obvious visual signals in response to water stimulation. As the humidity of the environment increases, both the fluorescence color and the fluorescence intensity show significant changes, and the two work together to enhance the visual effect of human eye observation.

[0077] Figure 4 This is a fluorescence spectrum diagram of the electrospun fiber film with a double pattern prepared in Example 1 in a dry-humid environment cycle; as can be seen from the figure, the fluorescence color changes and fluorescence intensity changes of the prepared electrospun fiber film are stable during multiple dry-humid environment cycles.

[0078] Figure 5 This is a fluorescence spectrum diagram of the electrospun fiber film with a double pattern prepared in Example 1 under fumigation with different solvents; it can be seen from the figure that under the fumigation of different solvents, the electrospun fiber film only produces a specific response to water.

[0079] Figure 6 This is a graph showing the current variation of the electrospun fiber film with a double pattern prepared in Example 1 under constant voltage conditions; as can be seen from the figure, the electrospun fiber film has a rapid humidity response and a fast fluorescence recovery, and can achieve real-time humidity sensing and rapid anti-counterfeiting authentication.

[0080] Figure 7 The first fluorescent pattern drawn by electrospinning with a double pattern prepared in Example 1 and the second fluorescent pattern obtained after anti-counterfeiting pattern transfer under visible light and ultraviolet light are fluorescent photographs; it can be seen from the figure that the fluorescent pattern cannot be observed under visible light ( Figure 7 a), the first blue fluorescence pattern can be observed under UV light under dry conditions ( Figure 7 b), by increasing the ambient humidity (breathing), it can be observed that part of the first fluorescent pattern maintains its original color while the other part turns yellow-green, presenting a double fluorescent pattern ( Figure 7 c).

[0081] Example 2

[0082] A method for preparing reversible color-changing fluorescent dual anti-counterfeiting fiber comprises the following steps:

[0083] 1) Preparation of polymer substrate polymethacrylic acid

[0084] ①Weighing and dissolving drugs

[0085] Weigh 1.500 g ± 0.001 g of methacrylic acid and 0.060 g ± 0.001 g of ammonium persulfate, add them into 6 ml of deionized water and shake until fully dissolved;

[0086] ②Synthesis and purification of polymer polymethacrylic acid

[0087] The above solution was bubbling with nitrogen to remove oxygen in the solution, and the solution was kept at 80° C. in a nitrogen atmosphere for 6 hours; after the above reaction was completed, the solution after the reaction was injected into a dialysis bag with a pore size of 3000 and sealed, and the dialysis bag was placed in deionized water for dialysis to remove residual initiators, monomers and other impurities; the dialysis process was carried out for three days, and the deionized water was replaced every 24 hours; after the dialysis was completed, freeze-drying was performed to obtain purified polymethacrylic acid powder, which was vacuum dried and stored;

[0088] 2) Preparation of fluorescent unit tetrakis(4-pyridylbiphenyl)ethylene

[0089] ①Weighing and dissolving drugs

[0090] 0.0648 g ± 0.0005 g of tetrakis(4-bromophenyl)ethylene, 0.0123 g ± 0.0005 g of pyridine-4-boric acid, 0.022 g ± 0.001 g of palladium acetate and 0.028 g ± 0.001 g of tricyclohexylphosphine were weighed respectively and added to a 50 mL three-necked flask with a reflux condenser; then 20 mL of 1,4-dioxane and 1 mL of potassium phosphate aqueous solution (potassium phosphate content 0.021 g ± 0.001 g) were added to the flask under argon;

[0091] ②Synthesis of tetrakis(4-pyridylbiphenyl)ethylene

[0092] The oxygen in the reaction system was removed by freeze-thaw method three times, and the mixture was heated under reflux under argon for 80 hours; after removing the volatile solvent by rotary evaporator, 10 mL of deionized water was added, and extracted with 20 mL of chloroform three times; the collected organic layer was washed with saturated potassium carbonate aqueous solution and deionized water, and dried with anhydrous sodium sulfate; after removing the solvent by rotary evaporator, the crude product was purified by silica gel column chromatography with methanol / chloroform mixed solvent (volume ratio 1:60) as eluent to obtain a light yellow powder, i.e. tetrakis(4-pyridylbiphenyl)ethylene;

[0093] 3) Preparation of humidity-responsive fluorescent fibers by electrospinning

[0094] ①Weighing and dissolving drugs

[0095] 1.000 g ± 0.001 g of the above-synthesized and purified polymethacrylic acid and 0.002 g ± 0.0001 g of the above-synthesized and purified tetrakis(4-pyridylbiphenyl)ethylene were weighed respectively, added into 9.0 g of deionized water, and stirred slowly for three days to obtain an electrospinning aqueous solution with a solid content of 10 wt%;

[0096] ②Electrospinning

[0097] The electrospinning needle with an inner diameter of 1 mm was used, the receiving end was aluminum foil, the electrospinning voltage was 17 kV, and the receiving end voltage was -2 kV; the receiving distance was 18 cm, and the spinning speed was 10 μL·min -1 During the electrospinning process, a mask can be arranged at the receiving end to achieve the drawing of the first fluorescent pattern;

[0098] First, the spinning solution is sucked into the syringe, and the bubbles therein are removed. The syringe is transferred to the injection device for electrospinning, and the injection parameters are adjusted. Aluminum foil is coated on the receiving roller, flattened and dusted, and then the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply. A mask is arranged at the receiving end, the receiving end rolling device and the transmitting end translation device are turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value. Then, the injection pump is turned on and the transmitting end power supply is gradually adjusted to the required voltage, and the corresponding electrospinning film can be obtained on the aluminum foil at the receiving end.

[0099] 4) Drawing of the second anti-counterfeiting pattern

[0100] ①Weighing and dissolving drugs

[0101] Weigh 0.500 g ± 0.001 g of polymethyl methacrylate and dissolve it in 15 ml of acetone to prepare a hydrophobic coating;

[0102] ② Pattern transfer

[0103] The target pattern is transferred onto the prepared electrospun film using a mask method or a stencil printing method. After the acetone evaporates naturally, the electrospun film with the transferred pattern is placed in a vacuum drying oven at 60° C. for two hours to make the hydrophobic pattern dense.

[0104] Example 3

[0105] A method for preparing reversible color-changing fluorescent dual anti-counterfeiting fiber comprises the following steps:

[0106] 1) Preparation of polymer substrate poly(2-acrylamide-2-methylpropanesulfonic acid)

[0107] ①Weighing and dissolving drugs

[0108] Weigh 1.000 g ± 0.001 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.040 g ± 0.001 g of ammonium persulfate, add to 4 ml of deionized water and shake until fully dissolved;

[0109] ②Synthesis and purification of polymer poly(2-acrylamido-2-methylpropanesulfonic acid)

[0110] The above solution was bubbling with nitrogen to remove oxygen in the solution, and the solution was kept at 60° C. in a nitrogen atmosphere for 6 hours. After the above reaction was completed, the solution after the reaction was injected into a dialysis bag with a pore size of 3000 and sealed, and the dialysis bag was placed in deionized water for dialysis to remove residual initiators, monomers and other impurities. The dialysis process was carried out for three days, and the deionized water was replaced every 24 hours. After the dialysis was completed, freeze-drying was performed to obtain purified poly (2-acrylamide-2-methylpropanesulfonic acid) powder, which was vacuum dried and stored;

[0111] 3) Preparation of humidity-responsive fluorescent fibers by electrospinning

[0112] ①Weighing and dissolving drugs

[0113] 0.600 g ± 0.001 g of the above-synthesized and purified poly (2-acrylamido-2-methylpropanesulfonic acid) and 0.002 g ± 0.0001 g of tetrakis (4-pyridylvinylphenyl) ethylene were weighed, added into 9.4 g of deionized water, and stirred slowly for three days to obtain an electrospinning aqueous solution with a solid content of 8 wt%;

[0114] ②Electrospinning

[0115] The electrospinning needle with an inner diameter of 1 mm was used, the receiving end was aluminum foil, the electrospinning voltage was 20 kV, and the receiving end voltage was -2 kV; the receiving distance was 18 cm, and the spinning speed was 15 μL·min -1 ; During the electrospinning process, a mask can be arranged at the receiving end to achieve the drawing of the first fluorescent pattern;

[0116] First, the spinning solution is sucked into the syringe, and the bubbles therein are removed. The syringe is transferred to the injection device for electrospinning, and the injection parameters are adjusted. Aluminum foil is coated on the receiving roller, flattened and dusted, and then the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply. A mask is arranged at the receiving end, the receiving end rolling device and the transmitting end translation device are turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value. Then, the injection pump is turned on and the transmitting end power supply is gradually adjusted to the required voltage, and the corresponding electrospinning film can be obtained on the aluminum foil at the receiving end.

[0117] 4) Drawing of the second anti-counterfeiting pattern

[0118] ①Weighing and dissolving drugs

[0119] Weigh 0.500 g ± 0.001 g of vaseline and dissolve it in 20 ml of n-hexane to prepare a hydrophobic coating;

[0120] ② Pattern transfer

[0121] The target pattern is transferred onto the prepared electrospun film using a mask method or a stencil printing method. After the n-hexane evaporates naturally, the electrospun film with the transferred pattern is placed in a vacuum drying oven at 30° C. for two hours to make the hydrophobic pattern dense.

[0122] Example 4

[0123] A method for preparing reversible color-changing fluorescent dual anti-counterfeiting fiber comprises the following steps:

[0124] 1) Preparation of polymer substrate polyacrylic acid

[0125] ①Weighing and dissolving drugs

[0126] Weigh 1.000 g ± 0.001 g of acrylic acid and 0.040 g ± 0.001 g of ammonium persulfate, add them to 4 ml of deionized water and shake until fully dissolved;

[0127] ②Synthesis and purification of polymer polyacrylic acid

[0128] The above solution was bubbling with nitrogen to remove oxygen in the solution, and the solution was kept at 60° C. in a nitrogen atmosphere for 6 hours. After the above reaction was completed, the solution after the reaction was injected into a dialysis bag with a pore size of 3000 and sealed, and the dialysis bag was placed in deionized water for dialysis to remove residual initiators, monomers and other impurities; the dialysis process was carried out for three days, and the deionized water was replaced every 24 hours. After the dialysis was completed, freeze-drying was performed to obtain purified polyacrylic acid powder, which was vacuum dried and stored;

[0129] 2) Preparation of fluorescent unit (2Z,2'Z)-2,2'-((1,4-phenylene)bis(3-(4-pyridylphenyl)acrylonitrile)

[0130] ①Weighing and dissolving drugs

[0131] Weigh 0.0642 g ± 0.0005 g of terephthalonitrile, 0.183 g ± 0.001 g of 4-(4-pyridyl)benzaldehyde, and 0.1344 g ± 0.0005 g of potassium tert-butoxide into a vial, add 2 ml of tert-butanol and shake thoroughly to dissolve;

[0132] ②Synthesis of (2Z,2'Z)-2,2'-((1,4-phenylene)bis(3-(4-pyridylphenyl)acrylonitrile)

[0133] After the terephthalonitrile solution and the 4-(4-pyridyl)benzaldehyde solution are fully mixed, potassium tert-butoxide solution is added, the mixture is fully shaken and stirred, and the mixture is kept at 40°C for 1 hour. The mixture is filtered, and tert-butanol is removed by a rotary evaporator. Hot ethanol is added, the mixture is fully shaken and dispersed, and the supernatant is removed after centrifugation. This is repeated three times; the mixture is dried in a vacuum oven at room temperature for 24 hours to obtain a light yellow powder;

[0134] 3) Preparation of humidity-responsive fluorescent fibers by electrospinning

[0135] ①Weighing and dissolving drugs

[0136] Weigh 0.800 g ± 0.001 g of the above-synthesized and purified polyacrylic acid and 0.002 g ± 0.0001 g of the above-synthesized and purified (2Z, 2'Z)-2,2'-((1,4-phenylene)bis(3-(4-pyridylphenyl)acrylonitrile) respectively, add them into 9.2 g of deionized water, and stir them slowly for three days to obtain an electrospinning aqueous solution with a solid content of 8 wt%;

[0137] ②Electrospinning

[0138] The electrospinning needle with an inner diameter of 1 mm was used, and the receiving end was aluminum foil. The electrospinning voltage was 15 kV, of which the receiving end voltage was -2 kV; the receiving distance was 18 cm, and the spinning speed was 10 μL·min -1 During the electrospinning process, a mask can be arranged at the receiving end to achieve the drawing of the first fluorescent pattern;

[0139] First, the spinning solution is sucked into the syringe, and the bubbles therein are removed. The syringe is transferred to the injection device for electrospinning, and the injection parameters are adjusted; the receiving roller is coated with aluminum foil, flattened and dusted, and then the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply; the receiving end rolling device is turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value, and then the injection pump is turned on and the syringe power supply is gradually adjusted to the required voltage, and the electrospinning film can be obtained on the aluminum foil at the receiving end;

[0140] 4) Drawing of the second anti-counterfeiting pattern

[0141] ①Weighing and dissolving drugs

[0142] Weigh 0.500 g ± 0.001 g of paraffin wax and dissolve it in 20 ml of ether to prepare a hydrophobic coating;

[0143] ② Pattern transfer

[0144] The target pattern is transferred onto the prepared electrospun film using a mask method or a stencil printing method. After the ether evaporates naturally, the electrospun film with the transferred pattern is placed in a vacuum drying oven at 60° C. for two hours to make the hydrophobic pattern dense.

[0145] Example 5

[0146] 1) Preparation of humidity-responsive fluorescent fibers by electrospinning

[0147] ①Weighing and dissolving drugs

[0148] Weigh 0.800 g ± 0.01 g of a commercially available 50% solid content polyacrylic acid aqueous solution with a molecular weight of 3000, 0.600 g ± 0.01 g of a commercially available polyvinyl pyrrolidone with a molecular weight of 40000, and 0.002 g ± 0.0001 g of tetrapyridyl tetraphenylethylene, add them into 8.6 g of deionized water, and stir them slowly for three days to obtain an electrospinning aqueous solution with a solid content of 10 wt%;

[0149] ②Electrospinning

[0150] The electrospinning needle with an inner diameter of 1 mm was used, and the receiving end was aluminum foil. The electrospinning voltage was 15 kV, of which the receiving end voltage was -2 kV; the receiving distance was 18 cm, and the spinning speed was 15 μL·min -1 ,During the electrospinning process, a mask can be arranged at the receiving end to achieve the drawing of the first fluorescent pattern;

[0151] First, the spinning solution is sucked into the syringe, and the bubbles therein are removed. The syringe is transferred to the injection device for electrospinning, and the injection parameters are adjusted; the receiving roller is coated with aluminum foil, flattened and dusted, and then the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply; the receiving end rolling device is turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value, and then the injection pump is turned on and the syringe power supply is gradually adjusted to the required voltage, and the electrospinning film can be obtained on the aluminum foil at the receiving end;

[0152] 2) Drawing of the second anti-counterfeiting pattern

[0153] ①Weighing and dissolving drugs

[0154] Weigh 0.500 g ± 0.001 g of paraffin wax and dissolve it in 20 ml of ether to prepare a hydrophobic coating;

[0155] ② Pattern transfer

[0156] The target pattern is transferred onto the prepared electrospun film using a mask method or a stencil printing method. After the ether evaporates naturally, the electrospun film with the transferred pattern is placed in a vacuum drying oven at 50° C. for two hours to make the hydrophobic pattern dense.

[0157] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0158] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a reversible humidity-responsive fluorescent color-changing system, comprising the following steps: A) mixing anionic polyelectrolytes, fluorescent molecules and water to obtain an electrospinning aqueous solution; the fluorescent molecules are fluorescent molecules that change color after receiving protons; B) electrospinning the electrospinning aqueous solution, arranging a mask at a receiving end to draw a first fluorescent pattern, and obtaining an electrospinning film having the first fluorescent pattern; C) Drawing a second anti-counterfeiting pattern on the surface of the electrospun film obtained in step B) using a waterproof coating to obtain a reversible humidity-responsive fluorescent color-changing system.

2. The preparation method according to claim 1, characterized in that: The anionic polyelectrolyte is polyacrylic acid, polymethacrylic acid or poly(2-acrylamide-2-methylpropanesulfonic acid); the fluorescent molecule is a compound having an amino group, an imino group or a pyridine group directly connected to a conjugated skeleton, and specifically, the fluorescent molecule is selected from tetrakis(4-pyridylbiphenyl)ethylene, tetrakis(4-pyridylvinylphenyl)ethylene or (2Z,2'Z)-2,2'-((1,4-phenylene)bis(3-(4-pyridylphenyl)acrylonitrile); the waterproof coating comprises a waterproof material and a solvent, and the waterproof material is selected from one or more of paraffin, polymethacrylic acid, polyethylene wax, polystyrene, polyvinyl fluoride and vaseline; the mass ratio of the anionic polyelectrolyte to the fluorescent molecule is (500-1000):

1.

3. The preparation method according to claim 1, characterized in that: The electrospinning steps are specifically as follows: The electrospinning aqueous solution is sucked into the syringe, and the syringe is transferred to the electrospinning injection device, and the injection parameters are adjusted; aluminum foil is coated on the receiving roller, the receiving end is connected to the negative pole of the power supply, and the syringe needle is connected to the positive pole of the power supply; a mask is arranged at the receiving end, the receiving end rolling device and the transmitting end translation mode are turned on, the high-voltage power supply is turned on, and the receiving end voltage is adjusted to the expected value, and then the injection pump is turned on and the transmitting end power supply is gradually adjusted to the required voltage to obtain an electrospinning film with a first fluorescent pattern.

4. The preparation method according to claim 1 or 3, characterized in that: The voltage of the electrostatic spinning is 10 to 20 kV, the voltage at the receiving end is -1.5 kV to -2.5 kV, the distance from the receiving end is 15 to 20 cm, and the spinning speed is 8 to 15 μm·min -1 ; The concentration of the electrospinning aqueous solution is 5 to 15 wt%.

5. The preparation method according to claim 1 or 3, characterized in that: The diameter of the spinning fibers in the electrostatic spinning film is 200-300 nm.

6. The preparation method according to claim 1, characterized in that: Step C) is specifically: Mixing a waterproof material and an organic solvent to obtain a waterproof coating; the waterproof material is selected from one or more of paraffin wax, polymethacrylic acid, polyethylene wax, polystyrene, polyvinyl fluoride and vaseline; The target pattern is transferred onto the surface of the electrostatically spun film by using a mask method or a stencil printing method with a waterproof coating, and the electrostatically spun film after the transfer pattern is dried to obtain a reversible color-changing fluorescent dual anti-counterfeiting pattern.

7. The preparation method according to claim 1, 2, 3 or 6, characterized in that: The electrospinning aqueous solution also includes an auxiliary polymer, which is selected from one or more of polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene glycol.

8. A reversible humidity-responsive fluorescent color-changing system, comprising an electrospun film having a first fluorescent pattern and a second anti-counterfeiting pattern composited on the surface of the first fluorescent pattern, wherein the electrospun film comprises anionic polyelectrolytes and fluorescent molecules, wherein the fluorescent molecules change color after receiving protons, and the second anti-counterfeiting pattern is drawn by a waterproof coating.

9. The reversible humidity-responsive fluorescent color-changing system according to claim 1, characterized in that: The electrospinning film further comprises an auxiliary polymer, and the auxiliary polymer is selected from one or more of polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene glycol.

10. Use of the reversible humidity-responsive fluorescent color-changing system prepared by the preparation method according to any one of claims 1 to 7 or the reversible humidity-responsive fluorescent color-changing system according to any one of claims 8 to 9 in the field of anti-counterfeiting.

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