CN110746327A - Azobenzene-graphene composite material and application thereof in color-changing encryption secrecy - Google Patents
Azobenzene-graphene composite material and application thereof in color-changing encryption secrecy Download PDFInfo
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Abstract
The invention discloses an azobenzene-graphene composite material and application thereof in color-changing encryption confidentiality, wherein azobenzene molecules are grafted to the surface of graphene in a covalent bond mode, and one azobenzene molecule is grafted every 20-40 carbon atoms; firstly, preparing azobenzene molecules; then carrying out reduction and oxidation graphene pretreatment; preparing an azobenzene molecular graphene composite material; and finally, combining the azobenzene graphene material with the thermochromic pigment to obtain the final encrypted security material. The azobenzene graphene material is heated and stimulated to release heat through ultraviolet light irradiation, so that the encryption and confidentiality processes are completed, and a new idea and a new method are provided for the encryption and confidentiality industry.
Description
Technical Field
The invention belongs to the field of functional composite materials, and particularly relates to an azobenzene graphene material and color-changing slurry integrated encryption security material and a preparation method thereof.
Background
With the development of science and technology in China, the competition of various industries is intensified day by day. And internationally, the influence of China is getting bigger and bigger, and the competition between the countries enters the stage of white fever. In this case, the security of the information is important. The information security and confidentiality of each enterprise and each country is very severe, and once a secret leakage event occurs, the loss caused by the secret leakage event is very disastrous. Therefore, it is necessary to develop a new encryption and security method and material. Solar energy has received much attention as a renewable energy source. The energy-saving device has the advantages that other energy sources do not have, for example, the energy is high, the energy-saving device is pollution-free in utilization and development, and is not influenced by geographical environment. Solar energy can be utilized to various fields by appropriate techniques and materials. The azobenzene molecule is a photoresponse molecule and has cis-trans isomerism. Under the irradiation of ultraviolet light, the trans-structure can be converted into a cis-structure by absorbing photon energy, and then the absorbed energy can be converted into heat energy to be released under the external stimulation of heating or visible light irradiation and the like, so that the trans-structure is converted back, the interaction force among azobenzene molecules can be increased by taking the graphene as a template, and the energy density of the azobenzene molecules is greatly improved. Most research is currently focused on increasing the energy density of the material, and is less involved in other aspects.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an azobenzene-graphene composite material and application thereof in color-changing encryption security, namely a composite material capable of converting solar energy into heat energy so as to achieve the effect of security encryption and an encryption security system based on the composite material are researched. Thermochromic pigments are characterized by a change in their own color when the ambient temperature reaches a certain temperature. The azobenzene graphene material is combined with the thermochromic pigment, and the characteristic that the color can be changed by using the heat emitted by the azobenzene graphene material and the color-changing slurry is utilized, so that a novel encryption and confidentiality system is obtained.
The technical purpose of the invention is realized by the following technical scheme:
the azobenzene-graphene composite material grafts heterocyclic azo molecules to the surface of graphene through covalent bonds.
In the technical scheme of the invention, graphene can be reduced by graphene oxide to obtain graphene (namely reduced graphene oxide), so that a benzene ring structure of the graphene is damaged, a compact six-membered ring (benzene ring) structure is subjected to loss of a certain carbon atom to form a vacancy, and a reaction site (hydroxyl OH and amino NH of heterocyclic azobenzene molecules) is provided for grafting of heterocyclic azobenzene2And the like) to graft one heterocyclic azobenzene molecule per 20-50 carbon atoms, preferably one azobenzene molecule per 20-30 carbon atoms.
The heterocyclic azobenzene molecule provides a group with an energy storage function for the azobenzene-graphene composite material, and has a structure shown in one of molecular formulas:
the azobenzene-graphene composite material is formed by bonding the heterocyclic azobenzene molecules to the surface of graphene, and specifically has a structure shown in one of the following molecular formulas
The preparation of the azobenzene molecule and azobenzene-graphene composite material is described in the following Chinese patents: an azobenzene molecule for solar heat storage and a preparation method thereof, 2015105747896; a three-branch azobenzene/graphene composite energy storage material and a preparation method thereof, 2016103482626; a double-branch azobenzene/graphene energy storage material and a preparation method thereof, 2016103770977; azobenzene derivatives containing electroattractive groups at ortho positions for solar thermal storage and a preparation method thereof, 2016108934776; 2017101510787, a linear double-branched azobenzene/graphene composite material and a preparation method and application thereof; application of the azobenzene-graphene composite material in preparing an anti-icing material, 2017102679190; azobenzene-based fluorinated derivatives and methods of making the same, 2017103180599; an alternating bilayer azobenzene/graphene composite energy storage material and a preparation method thereof, 2017108331434; a heterocyclic azobenzene/graphene solar heat storage material and a preparation method, 2017108331345; a double-grafted azobenzene/graphene composite energy storage material and a preparation method thereof, 2017108337093; a tridentate azobenzene molecule and a preparation method thereof, 2017109547309; an azobenzene side chain polymer energy storage material and a preparation method, 2018107923063; a double-grafted heterocyclic azobenzene graphene energy storage material and a preparation method, 2018108058460; a thermal inductance fluorocarbon functional coating containing azobenzene/carbon hybrid material, a preparation method and 2016100671683.
The following azobenzene molecules and corresponding azobenzene-graphene composite materials are taken as examples, and the preparation process is briefly explained
Preparation of azobenzene molecules: uniformly dispersing 5-amino-1, 3-benzene disulfonic acid and sodium hydroxide in deionized water, adding a sodium nitrite aqueous solution, and stirring for reaction to form a diazonium salt solution; dropwise adding the diazonium salt solution into hydrochloric acid for reaction in an ice bath, adding 3, 5-dimethoxyaniline, and continuously reacting in an inert protective gas atmosphere to obtain azobenzene molecules.
The using amount of the 5-amino-1, 3-benzene disulfonic acid is 20-30 mol parts, and each mol part is 1 mmol.
The molar ratio of the 5-amino-1, 3-benzene disulfonic acid to the sodium hydroxide is 1: 1.
the molar ratio of the 5-amino-1, 3-benzene disulfonic acid to the sodium nitrite is 1: (1-1.5).
The mol ratio of the 5-amino-1, 3-benzene disulfonic acid to the hydrogen chloride in the hydrochloric acid is 1: (3-5), wherein the concentration of the hydrochloric acid is 1 mol/L.
The stirring speed is 100-300 r/min, and the inert protective gas is nitrogen, helium or argon.
The diazonium salt solution is dropwise added to hydrochloric acid for 20-30 min, reacted for 1-2 hours in an ice bath, and continuously stirred and reacted for 1-5 hours, preferably 2-3 hours under the inert protective gas atmosphere.
After the reaction is finished, a crude product is obtained by suction filtration, and is washed by distilled water for a plurality of times, and then is recrystallized in a mixed solution of ethanol and acetone (the volume ratio of the ethanol to the acetone is 1:1), so that the target azo monomer is obtained.
Reduced Graphene Oxide (RGO) treatment: and adjusting the pH value of the aqueous solution of the uniformly dispersed graphene oxide to 8-9 by using sodium hydroxide, adding sodium borohydride, and reducing the graphene oxide by using the sodium borohydride under inert protective gas to obtain reduced graphene oxide. Centrifuging, filtering and washing the product for multiple times to obtain the prepared product; finally, the mixture is dispersed in water by using ultrasound. Specifically, the method comprises the following steps:
stirring is adopted in the reaction process to ensure that the mixture is uniformly dispersed and reacted, the stirring speed is 100-300 revolutions per minute, and the inert protective gas is nitrogen, helium or argon.
The reaction is carried out at 80 to 90 ℃ for 1 to 5 hours, preferably 2 to 3 hours.
The concentration of sodium borohydride is 10-30mg/ml (mass of sodium borohydride, mg/volume of water, ml), and the amount of sodium borohydride is excessive relative to graphene oxide, so that graphene oxide is fully reduced.
The preparation method of the azobenzene-graphene composite material comprises the following steps: uniformly dispersing azobenzene molecules and sodium nitrite in deionized water, and dropwise adding the mixture into hydrochloric acid under an ice bath condition for reaction to obtain an azobenzene-containing aqueous solution; and dropwise adding the water solution containing azobenzene into the water solution dispersed with the reduced graphene oxide under the ice bath condition to react to obtain the azobenzene-graphene composite material.
Azobenzene molecules and sodium nitrite are in an equimolar ratio, and the azobenzene molecules and the sodium nitrite react for 1 to 5 hours, preferably 1 to 2 hours under the ice bath condition to obtain an aqueous solution containing azobenzene, wherein the concentration of hydrochloric acid is 1M, and the dosage of the hydrochloric acid and deionized water is in an equal volume ratio.
The molecular amount of azobenzene is 1-5 mol portions, each mol portion is 1 mmol.
Dropwise adding an aqueous solution containing azobenzene into an aqueous solution of uniformly dispersed reduced graphene oxide, reacting for 5-10 hours, preferably 8-10 hours, under an ice bath condition, and then continuing to react for 20-50 hours, preferably 24-48 hours, at the room temperature of 20-25 ℃ so as to graft azobenzene onto the surface of graphene in a covalent bond mode.
And (3) carrying out vacuum filtration on the reaction product, washing for 3-6 times by using deionized water and DMF, and carrying out vacuum filtration to obtain the target product.
In the aqueous solution in which reduced graphene oxide is dispersed, the amount of reduced graphene oxide is 20 to 50 parts by mass, each part by mass being 1mg, preferably 20 to 30 parts by mass, and the amount of the aqueous solution in which reduced graphene oxide is uniformly dispersed is 50 to 100 parts by volume, each part by volume being 1ml, preferably 60 to 80 parts by volume.
The structural formula of cis-trans isomerization effect of the azobenzene-graphene composite material is as follows:
the heterocyclic azobenzene molecule and azobenzene-graphene composite material is applied to color change encryption confidentiality and information storage display.
The method comprises the steps of arranging a thermochromic pigment and an azobenzene-graphene composite material in an information content area, irradiating and heating part of the azobenzene-graphene composite material in the information content area by using ultraviolet light, shielding other areas from any stimulus, finally heating the information content area until the temperature is below the color change temperature of the thermochromic pigment, radiating the irradiated and heated azobenzene-graphene composite material under the heating stimulus, heating the information content area corresponding to the irradiated and heated azobenzene-graphene composite material to reach the color change temperature of the thermochromic pigment, so that the temperature difference exists between the area irradiated by the ultraviolet light and the area not irradiated in the information content area, the thermochromic pigment changes the color to display corresponding information, and the encryption and confidentiality processes are completed.
Wherein the heating is carried out to a temperature within 5 ℃ below the color change temperature of the thermochromic pigment.
Specifically, the preparation of the azobenzene graphene system color-changing encryption security material comprises the following steps: cutting 30-60 mg of the azobenzene graphene film obtained by suction filtration into a regular rectangle, and then printing the 65 ℃ thermochromic pigment on the surface of the polypropylene adhesive sticker by silk screen printing. And adhering a polypropylene film on the surface of the azobenzene graphene composite material, irradiating the azobenzene graphene composite material by ultraviolet light for 3-6 hours in different areas according to information content, and shielding other areas to avoid any stimulation. And finally, placing the material on a heating table, heating to 60 ℃, and releasing heat of the thermally-charged azobenzene graphene composite material under the heating stimulation, so that the temperature difference of 5 ℃ exists between the area irradiated by the ultraviolet light and the area not irradiated, the color of the thermochromic pigment is changed, the information is displayed, and the encryption and confidentiality processes are completed.
Drawings
FIG. 1 is an infrared spectrum of an azobenzene molecule in an example of the present invention.
Fig. 2 is a scanning electron microscope image of the azobenzene-graphene composite material in the embodiment of the invention.
Fig. 3 is a DSC (differential scanning calorimetry) chart of the azobenzene-graphene composite material according to the embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating the effect of the color-changing encryption security material of the azobenzene-graphene composite material according to the embodiment of the present invention.
Detailed Description
The following azobenzene molecules and corresponding azobenzene-graphene composites are used as examples to further illustrate the present invention, but not to limit the scope of the present invention.
Example 1
1) Preparation of azobenzene molecules: dissolving 20mmol of 5-amino-1, 3-benzene disulfonic acid and sodium hydroxide with equivalent weight (namely, the molar ratio of the sodium hydroxide to the 5-amino-1, 3-benzene disulfonic acid is equal) in deionized water, then dropwise adding an aqueous solution of 1.1 equivalent weight of sodium nitrite (1.1 times of the molar weight of the 5-amino-1, 3-benzene disulfonic acid) into the deionized water, after uniform dispersion, slowly dropwise adding the solution into 3 equivalent weight of 1mol/l hydrochloric acid (the hydrogen chloride is 3 times of the molar weight of the 5-amino-1, 3-benzene disulfonic acid), stirring for 2 hours under ice bath conditions, adding 1.2 equivalent weight of 3, 5-dimethoxyaniline (1.2 times of the molar weight of the 5-amino-1, 3-benzene disulfonic acid) and continuously reacting for 3 hours under the protection of nitrogen to obtain azobenzene molecules.
2) Pretreatment of reduced graphene oxide: adjusting the pH of the aqueous solution of the dispersed graphene oxide to 9 by using 20-25% by mass of a sodium carbonate aqueous solution, adding 40ml of the pH-adjusted graphene oxide aqueous solution into 20mg/ml of a sodium borohydride aqueous solution, and standing at 90 ℃ for 8 hours; obtaining the required RGO by centrifugation, filtration and washing with distilled water; and then redispersed in water by sonication.
3) Preparing an azobenzene graphene composite material: dissolving 3mmol of azobenzene molecules obtained in the step 1) and equivalent sodium nitrite in deionized water, dropwise adding the solution into 1mol/l hydrochloric acid solution under an ice bath condition, reacting for 2 hours, dropwise adding the solution into 30mg of reduced graphene oxide aqueous solution (the volume of water is 100ml) under the ice bath condition, reacting for 10 hours in an ice bath, and then reacting for 48 hours at room temperature; and (3) carrying out vacuum filtration, repeatedly washing with deionized water and DMF for many times, and finally carrying out vacuum drying to obtain the target product azobenzene graphene composite material.
4) Preparing an azobenzene graphene system color-changing encryption security material: cutting 30mg of the azobenzene graphene film obtained by suction filtration in the step 3) into a regular rectangle, and then printing the 65 ℃ thermochromic pigment on the surface of the polypropylene adhesive sticker by silk screen printing. And (3) sticking a polypropylene film on the surface of the azobenzene graphene composite material, irradiating the azobenzene graphene composite material by areas according to information content for 6 hours by using ultraviolet light for heat charging, and shielding other areas to avoid any stimulation. And finally, placing the material on a heating table, heating to 60 ℃, and releasing heat of the thermally-charged azobenzene graphene composite material under the heating stimulation, so that the temperature difference of 5 ℃ exists between the area irradiated by the ultraviolet light and the area not irradiated, the color of the thermochromic pigment is changed, the information is displayed, and the encryption and confidentiality processes are completed.
Example 2
1) Preparation of azobenzene molecules: dissolving 30mmol of 5-amino-1, 3-benzene disulfonic acid and equivalent sodium hydroxide in deionized water, dropwise adding 1.5 equivalent sodium nitrite solution into the deionized water, dispersing the solution uniformly, slowly dropwise adding the solution into 5 equivalent 1mol/l hydrochloric acid, stirring the solution for 2 hours under ice bath condition, adding 1 equivalent 3, 5-dimethoxyaniline, and continuously reacting the solution for 2 hours under the protection of nitrogen to obtain azobenzene molecules.
2) Pretreatment of reduced graphene oxide: adjusting the pH of the aqueous solution of the dispersed graphene oxide to 8 by using 20% sodium carbonate aqueous solution in percentage by mass, adding 40ml of the pH-adjusted graphene oxide aqueous solution into 20mg/ml sodium borohydride aqueous solution, and standing at 85 ℃ for 8 hours; obtaining the required RGO by centrifugation, filtration and washing with distilled water; and then redispersed in water by sonication.
3) Preparing an azobenzene graphene composite material: dissolving 2mmol of azobenzene molecules obtained in the step 1) and equivalent sodium nitrite in deionized water, dropwise adding the solution into 1mol/l hydrochloric acid solution under an ice bath condition, reacting for 1 hour, dropwise adding the solution into 20mg of the aqueous solution (60 ml of aqueous solution) of reduced graphene oxide obtained in the step 2) under the ice bath condition, reacting for 8 hours in an ice bath, and then reacting for 24 hours at room temperature; and (3) carrying out vacuum filtration, repeatedly washing with deionized water and DMF for many times, and finally carrying out vacuum drying to obtain the target product azobenzene graphene composite material.
4) Preparing an azobenzene graphene system color-changing encryption security material: cutting 40mg of the azobenzene graphene film obtained by suction filtration in the step 3) into a regular rectangle, and then printing the 65 ℃ thermochromic pigment on the surface of the polypropylene adhesive sticker by silk screen printing. And (3) sticking a polypropylene film on the surface of the azobenzene graphene composite material, irradiating the azobenzene graphene composite material by areas according to information content for 6 hours by using ultraviolet light for heat charging, and shielding other areas to avoid any stimulation. And finally, placing the material on a heating table, heating to 60 ℃, and releasing heat of the thermally-charged azobenzene graphene composite material under the heating stimulation, so that the temperature difference of 5 ℃ exists between the area irradiated by the ultraviolet light and the area not irradiated, the color of the thermochromic pigment is changed, the information is displayed, and the encryption and confidentiality processes are completed.
Example 3
1) Preparation of azobenzene molecules: dissolving 25mmol of 5-amino-1, 3-benzene disulfonic acid and equivalent sodium hydroxide in deionized water, dropwise adding 1.2 equivalent sodium nitrite solution into the deionized water, dispersing the solution uniformly, slowly dropwise adding the solution into 4 equivalent 1mol/l hydrochloric acid, stirring the solution for 2 hours under ice bath condition, adding 1.2 equivalent 3, 5-dimethoxyaniline, and continuously reacting for 3 hours under the protection of nitrogen to obtain azobenzene molecules.
2) Pretreatment of reduced graphene oxide: adjusting the pH of the aqueous solution of the dispersed graphene oxide to 9 by using 25% by mass of a sodium carbonate aqueous solution, adding 40ml of the pH-adjusted graphene oxide aqueous solution into 20mg/ml of a sodium borohydride aqueous solution, and standing at 90 ℃ for 7 hours; obtaining the required RGO by centrifugation, filtration and washing with distilled water; and then redispersed in water by sonication.
3) Preparing an azobenzene graphene composite material: dissolving 3mmol of azobenzene molecules obtained in the step 1) and equivalent sodium nitrite in deionized water, dropwise adding the solution into 1mol/l hydrochloric acid solution under an ice bath condition, reacting for 2 hours, dropwise adding the solution into 30mg of reduced graphene oxide aqueous solution (the volume of water is 50ml) obtained in the step 2) under the ice bath condition, reacting for 10 hours in the ice bath, and then reacting for 30 hours at room temperature; and (3) carrying out vacuum filtration, repeatedly washing with deionized water and DMF for many times, and finally carrying out vacuum drying to obtain the target product azobenzene graphene composite material.
4) Preparing an azobenzene graphene system color-changing encryption security material: cutting 60mg of the azobenzene graphene film obtained by suction filtration in the step 3) into a regular rectangle, and then printing the 65 ℃ thermochromic pigment on the surface of the polypropylene adhesive sticker by silk screen printing. And (3) sticking a polypropylene film on the surface of the azobenzene graphene composite material, irradiating the azobenzene graphene composite material by areas according to information content for 6 hours by using ultraviolet light for heat charging, and shielding other areas to avoid any stimulation. And finally, placing the material on a heating table, heating to 60 ℃, and releasing heat of the thermally-charged azobenzene graphene composite material under the heating stimulation, so that the temperature difference of 5 ℃ exists between the area irradiated by the ultraviolet light and the area not irradiated, the color of the thermochromic pigment is changed, the information is displayed, and the encryption and confidentiality processes are completed.
Infrared characterization was performed on azobenzene molecules prepared in the examples, as shown in FIG. 1, 1045cm-1And 1201cm-1Respectively belong to SO3-symmetric extensional vibration peak and antisymmetric extensional vibration peak. 1272cm-1The absorption peak of (A) is a C-O stretching vibration peak. 1340cm-1The absorption peak of (a) is an-N ═ N-group. 1430-1602 cm-1The absorption peak of (2) is a characteristic absorption peak of a benzene ring. The absorption peak of C-H in methoxyl is 2870cm-1And 2940cm-1About 3400-3500 cm-1The absorption peak of (A) is-OH group covered with-NH2The absorption peak of (1). From the above analysis, the target azobenzene molecule was successfully synthesized. The azobenzene-graphene composite material in the embodiment of the invention is characterized, as shown in the attached figures 2-3, the RGO surface has obvious folds, which shows that azobenzene molecules are grafted to the RGO surface, and the folds are mutually interpenetrated and stacked to be beneficial to the interaction between the RGOs and the formation of an interpenetration structure between the molecules; by DSC (differential Heat)Scanning calorimetry) to obtain exothermic peak of the material, then integrating the exothermic peak by software to obtain released energy, dividing the released energy by mass, and calculating corresponding energy density to reach 130-150 Wh/kg on average.
As shown in fig. 4, the thermochromic pigment and the azobenzene-graphene composite material are arranged in an information content area, ultraviolet light is used for irradiating and heating part of the azobenzene-graphene composite material in the information content area, other areas are shielded and do not receive any stimulation, finally, the information content area is heated to be below the color change temperature of the thermochromic pigment, the azobenzene-graphene composite material which is irradiated and heated is heated to release heat under the heating stimulation, the information content area corresponding to the azobenzene-graphene composite material is heated to reach the color change temperature of the thermochromic pigment, so that the temperature difference exists between the area irradiated by the ultraviolet light and the area not irradiated in the information content area, the thermochromic pigment is caused to change the color, corresponding information is displayed, and the encryption and confidentiality processes are completed. According to the invention, the preparation of the azobenzene molecule and the related azobenzene-graphene composite material is related to Chinese patents, and the prepared azobenzene molecule and the related azobenzene-graphene composite material show energy storage performance and can be suitable for the information encryption and confidentiality and information display process shown in the attached figure 4.
The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.
Claims (10)
1. An azobenzene-graphene composite material is characterized by having a structure shown in the following molecular formula.
2. The azobenzene-graphene composite material according to claim 1, wherein one heterocyclic azobenzene molecule is grafted per 20-50 carbon atoms, preferably per 20-30 carbon atoms, and the heterocyclic azobenzene molecule is represented by the following chemical formula.
3. The preparation method of the azobenzene-graphene composite material according to claim 1, wherein azobenzene molecules and sodium nitrite are uniformly dispersed in deionized water, and the mixture is dripped into hydrochloric acid under the ice bath condition to react to obtain an aqueous solution containing azobenzene; and dropwise adding the water solution containing azobenzene into the water solution dispersed with the reduced graphene oxide under the ice bath condition to react to obtain the azobenzene-graphene composite material.
4. The method for preparing an azobenzene-graphene composite material according to claim 3, wherein the Reduced Graphene Oxide (RGO) treatment: and adjusting the pH value of the aqueous solution of the uniformly dispersed graphene oxide to 8-9 by using sodium hydroxide, adding sodium borohydride, and reducing the graphene oxide by using the sodium borohydride under inert protective gas to obtain reduced graphene oxide. Centrifuging, filtering and washing the product for multiple times to obtain the prepared product; finally, the mixture is dispersed in water by using ultrasound.
5. The method for preparing the azobenzene-graphene composite material according to claim 3, wherein 5-amino-1, 3-benzene disulfonic acid and sodium hydroxide are uniformly dispersed in deionized water, a sodium nitrite aqueous solution is added, and a diazonium salt solution is formed through stirring reaction; dropwise adding the diazonium salt solution into hydrochloric acid for reaction in an ice bath, adding 3, 5-dimethoxyaniline, and continuously reacting in an inert protective gas atmosphere to obtain azobenzene molecules.
6. The method for preparing an azobenzene-graphene composite material according to any one of claims 3 to 5, wherein the 5-amino-1, 3-benzenedisulfonic acid is used in an amount of 20 to 30 parts by mole, each part by mole being 1 mmol; the molar ratio of the 5-amino-1, 3-benzene disulfonic acid to the sodium hydroxide is 1: 1; the molar ratio of the 5-amino-1, 3-benzene disulfonic acid to the sodium nitrite is 1: (1-1.5); the mol ratio of the 5-amino-1, 3-benzene disulfonic acid to the hydrogen chloride in the hydrochloric acid is 1: (3-5), wherein the concentration of hydrochloric acid is 1 mol/L; stirring at 100-300 rpm, and inert gas such as nitrogen, helium or argon; the diazonium salt solution is dropwise added to hydrochloric acid for 20-30 min, reacted for 1-2 hours in an ice bath, and continuously stirred and reacted for 1-5 hours, preferably 2-3 hours under the inert protective gas atmosphere.
7. The method for preparing azobenzene-graphene composite material according to any one of claims 3 to 4, wherein in the Reduced Graphene Oxide (RGO) treatment, stirring is adopted to uniformly disperse and react, the stirring speed is 100-300 revolutions per minute, and the inert shielding gas is nitrogen, helium or argon; during the reaction, the reaction is carried out for 1 to 5 hours, preferably 2 to 3 hours at the temperature of 80 to 90 ℃; the concentration of sodium borohydride is 10-30mg/ml (mass of sodium borohydride, mg/volume of water, ml), and the amount of sodium borohydride is excessive relative to graphene oxide, so that graphene oxide is fully reduced.
8. The method for preparing azobenzene-graphene composite material according to one of claims 3 to 5, wherein azobenzene molecules and sodium nitrite are in an equimolar ratio, and the azobenzene molecules and the sodium nitrite are reacted for 1 to 5 hours, preferably 1 to 2 hours, under ice bath conditions to obtain an aqueous solution containing azobenzene, wherein the hydrochloric acid concentration is 1M, and the amounts of the hydrochloric acid and the deionized water are in an equal volume ratio; the molecular amount of azobenzene is 1-5 mol portions, each mol portion is 1 mmol; dropwise adding an aqueous solution containing azobenzene into an aqueous solution of uniformly dispersed reduced graphene oxide, reacting for 5-10 hours, preferably 8-10 hours, under an ice bath condition, and then continuing to react for 20-50 hours, preferably 24-48 hours, at the room temperature of 20-25 ℃ so as to graft azobenzene onto the surface of graphene in a covalent bond manner; in the aqueous solution in which reduced graphene oxide is dispersed, the amount of reduced graphene oxide is 20 to 50 parts by mass, each part by mass being 1mg, preferably 20 to 30 parts by mass, and the amount of the aqueous solution in which reduced graphene oxide is uniformly dispersed is 50 to 100 parts by volume, each part by volume being 1ml, preferably 60 to 80 parts by volume.
9. The heterocyclic azobenzene molecule is applied to color-changing encryption security and information storage display, and is characterized by having a structure shown in one of molecular formulas.
X＝F，Cl，Br
10. The azobenzene-graphene composite material is applied to color-changing encryption security and information storage and display, and is characterized in that heterocyclic azobenzene molecules are bonded to the surface of graphene, and the structure is shown in one of the following molecular formulas.
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| CN117645296A (en) * | 2024-01-30 | 2024-03-05 | 四川大学 | High-heat-conductivity aromatic heterocyclic polymer-based graphite film and preparation method thereof |
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