CN111086986B - A kind of p-aminoazobenzene functionalized graphene material and preparation method thereof - Google Patents

Abstract

The invention discloses a p-aminoazobenzene functionalized graphene material and a preparation method thereof. The p-aminoazobenzene is obtained by a method of polymerization and recrystallization, and then a diazotization reaction is used to convert the azobenzene with amino functional groups at both ends. Molecules are grafted on the graphene surface. After characterization analysis, azobenzene molecules were successfully grafted on the surface of graphene, and the molar grafting rate could reach 10%, and the surface of graphene functionalized with p-aminoazobenzene was intact without obvious structural damage. The invention provides a method and application premise for surface modification of azobenzene material graphene.

Description

A kind of p-aminoazobenzene functionalized graphene material and preparation method thereof

technical field

The invention belongs to the field of nano-composite materials, and more particularly relates to a graphene material functionalized with p-aminoazobenzene and a preparation method thereof.

Background technique

Since 2010, graphene materials have developed rapidly in various fields such as energy, machinery, biology, and medicine due to their excellent electrical and thermal conductivity and stable structure. However, the research found that graphene has a relatively simple structure, less surface functional groups, and poor dispersibility, so it has been greatly limited in many research applications. In order to improve this defect, researchers advocate the surface functionalization of graphene to increase the active sites of graphene and change its dispersion properties, especially adding special functional groups of graphene, such as amino groups, sulfonic acid groups, hydroxyl groups, according to demand. Wait. Azobenzene is a common dye, not only rich in functional groups on the surface, but also its unique isomerization makes azobenzene molecules widely used in the fields of solar thermal storage and optical control. Azobenzene molecules with amino groups have high activity, and the amino groups on the surface are often used as active functional groups to provide growth sites for the polymerization of various polymer materials. This technology is widely used in the research and development of capacitors, the design of anti-corrosion materials and so on. With the continuous improvement of people's quality of life, and issues such as energy storage and environmental friendliness are becoming more and more sensitive, it has become very important to develop environmentally friendly materials for energy storage. After a long period of research, it has been found that azobenzene molecules with amino groups can be grafted on the surface of graphene by the method of covalent bond functionalization, and show high energy storage density, isomerization rate and long half-life, etc. performance. Moreover, azobenzene-functionalized graphene molecules can be compounded with various materials to obtain different kinds of graphene composite materials, such as azobenzene-functionalized graphene/polyaniline composite materials, azobenzene-functionalized graphite ene/polypyrrole composites, etc. Therefore, obtaining a preparation method or process of p-aminoazobenzene functionalized graphene has great potential for the development of energy storage, material anticorrosion, aerospace equipment and other aspects.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the deficiencies of the prior art, provide a kind of p-aminoazobenzene functionalized graphene material and preparation method thereof, namely prepare a kind of p-aminoazobenzene functionalized graphene material, p-aminoazobenzene functionalized graphene material Benzene molecules are grafted on the graphene surface in the form of covalent bonds.

The technical purpose of the present invention is achieved through the following technical solutions.

A p-aminoazobenzene functionalized graphene material has the structure shown in the following chemical formula.

That is, p-aminoazobenzene molecules are grafted to the graphene surface in the form of covalent bonds.

Moreover, the graphene is the graphene obtained by reducing the raw material graphene or graphene oxide (ie, reduced graphene oxide).

Furthermore, the p-aminoazobenzene molecule has a structure represented by the following molecular formula.

The p-aminoazobenzene molecules are grafted to the graphene surface in the form of covalent bonds, and the molar graft ratio is 10-30%, preferably 20-30%.

The preparation method of the graphene material of p-aminoazobenzene functionalization is carried out according to the following steps:

Step 1, synthesizing p-aminoazobenzene monomer (that is, the method for preparing p-aminoazobenzene)

The p-nitroaniline is evenly dispersed in concentrated sulfuric acid and diluted with water. After the temperature is raised to 70-80 degrees Celsius, ammonium persulfate is added for the reaction. Drying treatment; then disperse the dried product and sodium sulfide in a mixed solution of deionized water and ethanol, react at 80-90 degrees Celsius, and recrystallize the reacted precipitate in alcohol, at 60-90 degrees Celsius Vacuum drying at 70 degrees Celsius to obtain an orange powder, which is p-aminoazobenzene

In step 1, the molar ratio of ammonium persulfate and p-nitroaniline is (1-5):1, preferably (2-3):1.

In step 1, the molar ratio of sodium sulfide and p-nitroaniline is (2-5):1, preferably (2.5-3):1.

In step 1, p-nitroaniline is uniformly dispersed in concentrated sulfuric acid and diluted with water, the volume ratio of water and concentrated sulfuric acid is (1-5): 1, and the concentrated sulfuric acid is sulfuric acid with a mass percentage of 95-98 wt.

In step 1, the time for adding ammonium persulfate to carry out the reaction is 1-5 hours, preferably 3-5 hours.

In step 1, the reaction is carried out at 80-90 degrees Celsius for 1-5 hours, preferably 3-5 hours.

In step 1, mechanical or ultrasonic stirring is selected during the reaction, and the stirring speed is 100-300 revolutions per minute.

In step 1, in a mixed solution of deionized water and ethanol, the two are in an equal volume ratio.

Step 2, prepare p-aminoazobenzene functionalized graphene material

p-aminoazobenzene and graphene are dispersed in hydrochloric acid to form a suspension, the aqueous solution of sodium nitrite is added dropwise to it under ice-bath conditions, and the reaction is continuously stirred to obtain p-aminoazobenzene functionalized graphene material , p-aminoazobenzene and sodium nitrite are in an equimolar ratio.

In step 2, the ice bath condition is 0-5 degrees Celsius.

In step 2, mechanical or ultrasonic agitation is used, and the speed is 100-500 revolutions per minute.

In step 2, the hydrochloric acid is an aqueous hydrogen chloride solution with a concentration of 1-5 mol/L.

In step 2, the dropping rate is 1-10 ml per minute, and the entire reaction time is 10-30 hours, preferably 15-26 hours.

In step 2, after the reaction is completed, filter, wash twice with absolute ethanol and deionized water each, that is, the graphene material functionalized with p-aminoazobenzene.

In the technical scheme of the present invention, graphene selects the graphene obtained by reduction of graphene oxide, first obtains graphene oxide suspension according to Hummers method or improved method, and then adopts hydrazine hydrate and nitrogen atmosphere for reduction, such as at 80- The reaction is carried out at 90 degrees Celsius for 6-8 hours to obtain reduced graphene oxide (ie, graphene). This method avoids the influence of substances such as sodium borohydride and sodium hydroxide in the previous scheme (such as salt generation), and obtains relatively The perfect graphene structure avoids the damage of the benzene ring structure of graphene caused by the previous oxidation treatment. In the process of preparing p-aminoazobenzene functionalized graphene material, the method of first dispersing the reaction substances (p-aminoazobenzene, graphene), and then dropwise addition of sodium nitrite, makes each participating substance react effectively, The formation of azobenzene salt and the amide-bonded benzene ring are carried out almost at the same time, which improves the overall reaction efficiency and avoids the defects of forming azobenzene salt and then adding graphene for the reaction in the previous scheme, such as insufficient reaction and bonding of azobenzene salt. Branches etc. The prepared p-aminoazobenzene-functionalized graphene material has both the properties of graphene and azobenzene molecules, and will be used in heat storage materials, polymer structure skeleton materials and photodeformation in the future, and has broad application prospects.

Description of drawings

Fig. 1 is the nuclear magnetic resonance spectrum of p-aminoazobenzene prepared by the present invention.

Fig. 2 is the scanning electron microscope photograph of the p-aminoazobenzene functionalized graphene prepared by the present invention.

Fig. 3 is the infrared spectrogram of the p-aminoazobenzene functionalized graphene prepared by the present invention.

Fig. 4 is the XPS spectrogram (1) of the p-aminoazobenzene functionalized graphene prepared by the present invention.

Fig. 5 is the XPS spectrum (2) of the p-aminoazobenzene functionalized graphene prepared by the present invention.

Detailed ways

The technical solutions of the present invention will be further described in detail below with reference to specific embodiments, rather than limiting the scope of the present invention. Mechanical stirring was adopted in the reaction, and the speed was 200 revolutions per minute; the dropping rate was 10 ml per minute; and the temperature of the ice bath was controlled to be 0-4 degrees Celsius.

Example 1

1) Synthesis of p-aminoazobenzene monomer: 10 g of p-nitroaniline was dispersed in 80 mL of concentrated sulfuric acid, then slowly added to 160 mL of deionized water for dilution, the temperature was raised to 70 ° C, and 3 times of p-nitroso was slowly added. The molar amount of ammonium persulfate of aniline was added and the reaction was continued for 5 hours. The precipitate was recrystallized in glacial acetic acid, and the product was vacuum-dried at 70°C for 24 hours. Then, the above product and 2.5 times the molar amount of p-nitroaniline sodium sulfide were dispersed in a mixed solution of deionized water and ethanol (equivalent volume ratio), and reacted at 85 ° C for 3 hours, and the precipitate was recrystallized in alcohol, Then vacuum-dried at 70 °C for 24 h to obtain an orange-yellow powder, which is p-aminoazobenzene.

2) Preparation of p-aminoazobenzene-functionalized graphene material: using diazotization reaction, first disperse 1.5 g p-aminoazobenzene in 100 mL of 1 mol/L hydrochloric acid solution, treat in an ice bath for 1 h, and then disperse the graphite The alkene material was dispersed in the above mixed solution and reacted for 2h. Then, sodium nitrite in an equimolar amount with p-aminoazobenzene was dissolved in deionized water, and slowly added dropwise to the mixed solution. After the dropwise addition was completed, the reaction was continued for 24 hours in an ice bath. After the reaction is completed, filter, wash twice with absolute ethanol and deionized water each, and vacuum dry at 80° C. to obtain a graphene material functionalized with p-aminoazobenzene.

Example 2

1) Synthesis of p-aminoazobenzene monomer: 15 g of p-nitroaniline was dispersed in 100 mL of concentrated sulfuric acid, then slowly added to 150 mL of deionized water for dilution, the temperature was raised to 70°C, and 5 times of p-nitroaniline was slowly added. The molar amount of ammonium persulfate of aniline was added and the reaction was continued for 1 h. The precipitate was recrystallized in glacial acetic acid, and the product was vacuum-dried at 70 °C for 24 h. Then, the above product and 5 times the molar amount of p-nitroaniline sodium sulfide were dispersed in a mixed solution of deionized water and ethanol (equivalent volume ratio), and reacted at 85 ° C for 5 hours, and the precipitate was recrystallized in alcohol. , and then vacuum-dried at 70 °C for 24 h to obtain an orange powder, which is p-aminoazobenzene.

2) Preparation of p-aminoazobenzene functionalized graphene material: Utilize diazotization reaction, at first 2g p-aminoazobenzene is dispersed in the hydrochloric acid solution of 80mL 1mol/L, then graphene material is dispersed in above-mentioned mixing solution and react for 3h. Then, sodium nitrite in an equimolar amount with p-aminoazobenzene was dissolved in deionized water, and slowly added dropwise to the mixed solution. After the dropwise addition was completed, the reaction was continued for 24 hours in an ice bath. After the reaction is completed, filter, wash twice with absolute ethanol and deionized water each, and vacuum dry at 80° C. to obtain a graphene material functionalized with p-aminoazobenzene.

Example 3

1) Synthesis of p-aminoazobenzene monomer: 10 g of p-nitroaniline was dispersed in 80 mL of concentrated sulfuric acid, then slowly added to 160 mL of deionized water for dilution, the temperature was raised to 70°C, and 2 times of p-nitroso was slowly added. The molar amount of ammonium persulfate of aniline was added and the reaction continued for 3 hours, the precipitate was recrystallized in glacial acetic acid, and the product was vacuum-dried at 70°C for 24 hours. Then, the above product and 3 times the molar amount of p-nitroaniline sodium sulfide were dispersed in a mixed solution of deionized water and ethanol (equivalent volume ratio), and reacted at 85 ° C for 5 h, and the precipitate was recrystallized in alcohol. , and then vacuum-dried at 70 °C for 24 h to obtain an orange powder, which is p-aminoazobenzene.

2) Preparation of p-aminoazobenzene functionalized graphene material: Utilize diazotization reaction, at first 1.5g p-aminoazobenzene is dispersed in the hydrochloric acid solution of 100mL 1mol/L, then graphene material is dispersed in the above-mentioned hydrochloric acid solution. mixed solution and reacted for 3h. Then, sodium nitrite in an equimolar amount with p-aminoazobenzene was dissolved in deionized water, and slowly added dropwise to the mixed solution. After the dropwise addition was completed, the reaction was continued for 24 hours in an ice bath. After the reaction is completed, filter, wash twice with absolute ethanol and deionized water each, and vacuum dry at 80° C. to obtain a graphene material functionalized with p-aminoazobenzene.

为-NH₂的积分面积，S_N为N元素的积分面积。代入计算数据N＝(0.108/1)*100％＝10.8％，所以判定偶氮的(摩尔)接枝率约为10.8％。The p-aminoazobenzene and p-aminoazobenzene-functionalized graphene of the present invention are characterized, taking Example 1 as an example. As shown in Figure 1, the instrument used for the detection is a nuclear magnetic resonance analyzer of Varian Company. As can be seen from the figure, there are three peaks in the spectrum, δ=6.27 is the vibration peak at p-aminoazobenzene-NH ₂ , δ=6.83(t, 2H), 8.06(t, 2H) is the azobenzene ring On the vibration peak of H, the NMR results proved that the p-aminoazobenzene material was successfully prepared. As shown in Figure 2, it can be clearly seen that the graphene nanosheets are transparent and have a clear wrinkle shape, which proves that the graphene oxide under the new process is very thin and has a large specific surface area. The structure is not damaged such as agglomeration, and the structure is complete. This also directly proves that under the process of the present invention, the graphene preparation effect is more remarkable. Figure 3 is the FTIR image of graphene G and p-aminoazobenzene-functionalized graphene G-PAZO. It can be seen from the figure that the spectrum of G and G-PAZO has an absorption peak at 3400cm ^-1 , which is graphene OH stretching vibration peak of 1730cm ^-1 is the stretching vibration peak of C=O, 1626cm ^-1 is the stretching vibration peak of C=C, 1356cm ^-1 is the bending vibration peak of N=N, 1147cm ^-1 is the -CN- The stretching vibration peak of , the N element comes from azobenzene, which proves that G-PAZO was successfully prepared. XPS is a characterization method used to determine the elemental and elemental content composition of a sample. It can be seen from Fig. 4 that the prepared materials have C and N elements, and Fig. 5 is the peak effect diagram of the N element of the p-aminoazobenzene-functionalized graphene G-PAZO. The integral area of all N elements is used as the denominator. The integral area of the sub-peak corresponding to _-NH2 is the molecule, and the molar graft ratio is calculated. It can be seen from the figure that the peaks of nitrogen-containing compounds can be decomposed into four peaks at 398.8eV, 399.6eV, 400.3eV and 401.7eV, corresponding to aniline (=N-), quinoid amine (-NH-), Nitrogen cation radicals (NH ⁺ ) and amino cations (-NH ₂ ). The elemental content was calculated using the following formula: where

is the integral area of _-NH2 , and S _N is the integral area of the N element. Substituting the calculation data N=(0.108/1)*100%=10.8%, it is determined that the (molar) graft ratio of azo is about 10.8%.

By adjusting the process parameters according to the content of the present invention, the preparation of the material of the present invention can be realized, and the performance is basically consistent with the present invention, that is, the grafting rate can reach 10-30%. The present invention has been exemplarily described above. It should be noted that, without departing from the core of the present invention, any simple deformation, modification, or other equivalent replacements that can be performed by those skilled in the art without any creative effort fall into the scope of the present invention. the scope of protection of the invention.

Claims (7)

1. a p-aminoazobenzene functionalized graphene material, is characterized in that, has the structure shown in the following chemical formula, p-aminoazobenzene molecule is grafted to graphene surface with covalent bond form, and the molar graft ratio is 10-30%;

The p-aminoazobenzene molecule has the structure shown in the following molecular formula:

The p-aminoazobenzene functionalized graphene material is carried out according to the following steps: Step 1, Synthesis of p-aminoazobenzene monomer The p-nitroaniline is evenly dispersed in concentrated sulfuric acid and diluted with water. After the temperature is raised to 70-80 degrees Celsius, ammonium persulfate is added for the reaction. Drying treatment; then disperse the dried product and sodium sulfide in a mixed solution of deionized water and ethanol, react at 80-90 degrees Celsius, and recrystallize the reacted precipitate in alcohol, at 60-90 degrees Celsius Vacuum drying at 70 degrees Celsius to obtain orange powder, which is p-aminoazobenzene; Step 2, prepare p-aminoazobenzene functionalized graphene material p-aminoazobenzene and graphene are dispersed in hydrochloric acid to form a suspension, the aqueous solution of sodium nitrite is added dropwise to it under ice-bath conditions, and the reaction is continuously stirred to obtain p-aminoazobenzene functionalized graphene material , p-aminoazobenzene and sodium nitrite are in an equimolar ratio. 2. a kind of p-aminoazobenzene functionalized graphene material according to claim 1 is characterized in that, graphene is raw material graphene, or selects the graphene obtained after graphene oxide is reduced by hydrazine hydrate. 3. a kind of p-aminoazobenzene functionalized graphene material according to claim 1 or 2, is characterized in that, p-aminoazobenzene molecule is grafted to graphene surface with covalent bond form, and the molar graft ratio 20-30%. 4. a preparation method of the functionalized graphene material of p-aminoazobenzene, is characterized in that, carry out according to the following steps: Step 1, Synthesis of p-aminoazobenzene monomer The p-nitroaniline is evenly dispersed in concentrated sulfuric acid and diluted with water. After the temperature is raised to 70-80 degrees Celsius, ammonium persulfate is added for the reaction. Drying treatment; then disperse the dried product and sodium sulfide in a mixed solution of deionized water and ethanol, react at 80-90 degrees Celsius, and recrystallize the reacted precipitate in alcohol, at 60-90 degrees Celsius Vacuum drying at 70 degrees Celsius to obtain orange powder, which is p-aminoazobenzene; Step 2, prepare p-aminoazobenzene functionalized graphene material p-aminoazobenzene and graphene are dispersed in hydrochloric acid to form a suspension, an aqueous solution of sodium nitrite is added dropwise to it under ice bath conditions, and the reaction is continuously stirred to obtain p-aminoazobenzene functionalized graphene material , p-aminoazobenzene and sodium nitrite are in an equimolar ratio. 5. the preparation method of a kind of p-aminoazobenzene functionalized graphene material according to claim 4, is characterized in that, in step 1, the mol ratio of ammonium persulfate and p-nitroaniline is (1- 5): 1; the mol ratio of sodium sulfide and p-nitroaniline is (2-5): 1; p-nitroaniline is evenly dispersed in the vitriol oil and diluted with water, and the volume ratio of water and vitriol oil is (1) -5): 1, the vitriol oil is the sulfuric acid of mass percent 95-98wt; In the mixed solution of deionized water and ethanol, the two are equal volume ratios. 6. the preparation method of a kind of p-aminoazobenzene functionalized graphene material according to claim 4, is characterized in that, in step 1, the time that adds ammonium persulfate to react is 1-5 hours; The reaction is carried out at 80-90 degrees Celsius for 1-5 hours; mechanical or ultrasonic stirring is selected during the reaction, and the stirring speed is 100-300 revolutions per minute. 7. the preparation method of a kind of p-aminoazobenzene functionalized graphene material according to claim 4, is characterized in that, in step 2, ice bath condition is 0-5 degrees Celsius; Adopt mechanical or ultrasonic to stir , the speed is 100-500 rpm; the hydrochloric acid is an aqueous solution of hydrogen chloride with a concentration of 1-5 mol/L; the dropping rate is 1-10 ml per minute, and the entire reaction time is 10-30 hours.

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