CN112341648B

CN112341648B - Preparation method of nano composite film containing europium ion nano cellulose/modified graphene oxide

Info

Publication number: CN112341648B
Application number: CN202011169400.7A
Authority: CN
Inventors: 郭凯; 史利娜; 沈磊; 李玉光; 季栋; 李亚军; 黄达; 刘一寰; 方正; 胡欣; 朱宁
Original assignee: Nanjing Advanced Biomaterials And Process Equipment Research Institute Co ltd
Current assignee: Nanjing Advanced Biomaterials And Process Equipment Research Institute Co ltd
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2022-03-11
Anticipated expiration: 2040-10-28
Also published as: CN112341648A

Abstract

The invention discloses a preparation method of a europium ion-containing nanocellulose/modified graphene oxide nanocomposite film. The composite film is prepared by modifying cellulose with the diameter of 3-25 nm and the length of 100-10 mu m by europium carboxylate ions and then compounding the modified cellulose with Graphene Oxide (GO) grafted by hexamethylene diisocyanate. The composite film provided by the invention has the advantages of lower dielectric loss, higher dielectric constant, breakdown field strength and energy storage density. The composite film has wide and potential application prospect in the aspect of dielectric energy storage.

Description

Preparation method of nano composite film containing europium ion nano cellulose/modified graphene oxide

Technical Field

The invention belongs to the technical field of nano composite films, and particularly relates to a preparation method of a nano composite film containing europium ion nano cellulose/modified graphene oxide.

Background

The biological polymer cellulose is an inexhaustible raw material of a plurality of environment-friendly devices and is the most abundant natural polymer on the earth. The cellulose has good biocompatibility, biodegradability and renewability, which provides a wide source for the nano-cellulose and also has the advantages of low price, large yield and the like; in addition, the cellulose nano-film has good flexibility, good light transmittance and a compact structure, and is an ideal candidate material for the bio-based dielectric material. The dielectric constant, breakdown field strength, charge-discharge efficiency and long-acting stability of the cellulose-based polymer can be obviously improved by performing functional modification and compounding on the cellulose-based polymer, so that the energy storage density and the cycle life of the cellulose-based dielectric material are improved.

Graphene has a uniform layered structure, and is widely used for preparing electrical materials due to its unique honeycomb structure, excellent electrical conductivity, low cost, easy processing, and the like. Through carrying out graft modification to graphene oxide, the problem that graphene is easy to gather in the synthetic process is solved, and the material performance composed of graphene is improved, so that the performance of GO is improved. The advantages of the nano-cellulose and the modified graphene can be fully utilized by compounding the nano-cellulose and the modified graphene, and a composite membrane material with good dielectric energy storage performance is obtained.

However, at present, the filler is usually added into the cellulose to introduce structural defects, so that the gaps of the composite layer become larger.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the defects of the prior art, the invention provides a preparation method of a nano composite film containing europium ion nano-cellulose/modified graphene oxide.

The technical scheme is as follows: in order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a nano composite film containing europium ion nano cellulose/modified graphene oxide comprises the following steps:

1) preparation of nanocellulose dispersion (TOCN):

dissolving TEMPO and NaBr, adding natural cellulose and NaClO, adjusting the pH value of a system to 9-11, carrying out oxidation reaction for 0.5-7 h at 10-30 ℃, filtering, washing, drying, and finally dispersing in deionized water to form a nano cellulose dispersion liquid;

2) preparation of graft-Modified Graphene Oxide (MGO):

dispersing Graphene (GO) in anhydrous dimethylacetamide (DMAc), adding HMDI (dimethyl formamide) and stirring at 100-120 ℃ to prepare an HMDI modified graphene oxide solution;

3) preparing a TOCN/modified graphene oxide nano dispersion liquid:

mixing the nano-cellulose dispersion liquid with the oxidized graphene solution modified by HMDI, and then stirring and ultrasonically treating the mixed dispersion liquid to prepare a TOCN/modified oxidized graphene nano-dispersion liquid;

4) preparing a nano composite film containing europium ion nano cellulose/modified graphene oxide:

casting the TOCN/modified graphene oxide dispersion liquid into a film, drying, and then immersing into Eu (NO)₃)₃Forming a hydrogel film in the solution, washing and air-drying to obtain the TOCN-Eu/MGO film.

Preferably, the method comprises the following steps:

in the step 1), TEMPO, NaBr, natural cellulose and NaClO are mixed according to the mass ratio of 1: (1-10): (10-100): (10-100).

In the step 1), the natural cellulose is one or more of wood pulp, cotton cellulose, hemp fiber, coconut shell, bagasse, corn shell, wheat straw or rice and other cellulose; the dispersion is carried out by mechanical stirring or ultrasonic.

In the step 2), the mass ratio of the graphene to the HDMI is 1: (9-11).

In the step 3), in the dispersion liquid, the nano-cellulose dispersion liquid accounts for 97-99.5% by volume, and the HMDI modified graphene oxide solution accounts for 0.5-3% by volume.

In the step 3), the concentration of the nano-cellulose dispersion liquid is 0.1-1% (mass concentration), wherein the diameter of the nano-cellulose is 3-25 nm, and the length of the nano-cellulose is 100-10 μm.

Step (ii) of4) In (1), the Eu (NO)₃)₃The concentration of the solution is 0.005-0.02 mol/L.

In the step 4), the drying temperature is 35-45 DEG^oC。

In step 4), the immersion into Eu (NO)₃)₃The time in the solution is 1-1000 minutes.

The method for preparing the nano-cellulose by the TEMPO method can effectively and selectively catalyze and oxidize primary alcohol hydroxyl on the C6 position of the cellulose into carboxyl. Under an alkaline environment, the negative potential on the surface of the nano-cellulose can be improved, so that mutual repulsion is generated between the nano-celluloses, the interaction between the nano-celluloses is weakened, and the nano-cellulose is finally separated from the natural cellulose; trivalent rare earth europium ion (Eu)³⁺) Has excellent photoelectric property, and is expected to be used for manufacturing novel anti-counterfeiting equipment, sensor systems and the like. Eu (Eu)³⁺The modified cellulose material can improve the processability of rare earth ions, reduce environmental pollution and improve the dielectric property of the cellulose-based material.

The invention adopts TEMPO method to prepare the nano-cellulose, the method is convenient and fast, the diameter of the obtained nano-cellulose is small and uniform, and the nano-cellulose can obviously play a role in enhancing when being compounded with other materials; graphene oxide with good electrical properties is selected to be grafted and modified and then used as a filler to be added into nano-cellulose to form a TOCN/MGO nano-composite material, and in order to further improve the dielectric properties of the material, the material is further soaked in Eu (NO)₃)₃In the solution, the pores in the film material can be reduced, the density of the film material can be increased, and the dielectric property of the composite material can be improved.

Has the advantages that: compared with the prior art, the invention has the following advantages:

1. according to the invention, nano-cellulose treated by a TEMPO oxidation method with a specific diameter and length is selected to be compounded with graphene oxide obtained by a specific grafting modification means, and then the compound film is soaked in a europium nitrate solution, so that pores in the obtained composite film laminated structure are reduced; the prepared composite film which is soaked in the europium nitrate solution for different time periods has lower dielectric loss, higher dielectric constant, breakdown field strength and energy storage density. The high-performance nano composite film has wide application prospect in light-emitting, photoelectric and energy storage devices as a multifunctional material.

2. According to the preparation method, the HMDI is selected to graft and modify the graphene oxide to prepare the MGO, the operation is simple, the heating and stirring are only carried out, and the prepared MGO dispersion liquid has higher stability compared with a Graphene Oxide (GO) dispersion liquid before modification.

3. The invention mixes the TOCN dispersion liquid with the MGO as a physical process, does not generate chemical reaction, and has simple process, convenient operation and no pollution to the environment; the europium nitrate is adopted to soak the TOCN/MGO composite membrane, the treatment process is simple and convenient, the requirement on the whole process equipment is not high, and the method is favorable for industrial production.

Detailed Description

The following examples are given to further illustrate the embodiments of the present invention. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Example 1

The preparation method of the europium ion-containing nanocellulose/modified graphene oxide nanocomposite film comprises the following steps:

1) preparation of TOCN dispersion: taking 0.01 g of TEMPO and 0.01 g of sodium bromide, adding the TEMPO and the sodium bromide into 1000 ml of deionized water together, magnetically stirring for 10 min at the rotating speed of 500 r/min to fully and uniformly mix the TEMPO and the sodium bromide until the TEMPO and the sodium bromide are completely dissolved, adding 1 g of cotton linter into the system, adding 0.1 g of sodium hypochlorite into the system, dropwise adding 0.1 mol/L of sodium hydroxide solution into the system to keep the pH value of the system to be 9, reacting for 5 hours, filtering oxidized cellulose, fully washing for more than 3 times by using the deionized water, and drying to obtain TEMPO oxidized cellulose; and then placing the nano-crystalline cellulose into a beaker, adding deionized water for dispersion, then mechanically stirring for 6 min, and carrying out ultrasonic treatment for 12 min to finally obtain nano-crystalline cellulose dispersion with the concentration of 0.3%, namely 0.3% TOCN dispersion.

2) Preparing Modified Graphene Oxide (MGO) by adding 20 mg of GO into 20 ml of anhydrous dimethylacetamide (DMAc), stirring and dispersing for 30 minutes, and addingIn 0.2 g of HMDI and at 110^oStirring for three hours under the condition of C.

3) Preparing a TOCN/modified graphene oxide composite membrane: mixing the prepared TOCN dispersion liquid with modified graphene oxide according to a volume ratio of 99.5:0.5 (marked as TOCN-Eu/MGO0.5), then stirring the mixed dispersion liquid with magnetons for 30 min, performing ultrasonic treatment for 4 min, casting the mixture into a film after uniform mixing, and performing film casting at 40 DEG^oC, drying in an oven to form a film; wherein the modified graphene oxide accounts for 0.5% of the total volume of the composite membrane.

4) Preparing nano composite film containing europium ion nano cellulose/modified graphene oxide (TOCN-Eu/MGO), immersing the prepared TOCN/MGO composite film into 0.01M Eu (NO)₃)₃The solution was washed with distilled water for 100 min to form a hydrogel film, and then air-dried at room temperature to prepare a TOCN-Eu/MGO0.5 film, wherein MGO is 0.5% of the total volume of the composite film.

The dielectric constant, dielectric loss and breakdown strength of the pure TOCN film prepared in the embodiment are tested by using an E4980AL-102LCR precision tester and a ZJC-50kV voltage breakdown tester, and the test result shows that the dielectric constant of the pure TOCN film prepared in the embodiment is about 118 at the frequency of 1 kHz, the dielectric loss is about 0.05 and the breakdown strength is only 143 kV/mm.

Example 2

2) Modified Graphene Oxide (MGO) was prepared by adding 20 mg of GO to 20 ml of anhydrous dimethylacetamide (DMAc), stirring for 30 minutes, adding 0.2 g of HMDI and dispersing at 110 deg.C^oStirring for three hours under the condition of C.

3) Preparing a TOCN/modified graphene oxide composite membrane: mixing the prepared TOCN dispersion liquid and modified graphene oxide according to a volume ratio of 99:1 (marked as TOCN-Eu/MGO1), then stirring magnetons of the mixed dispersion liquid for 30 min, performing ultrasonic treatment for 4 min, uniformly mixing, casting to form a film, and performing film formation at 40 DEG C^oC, drying in an oven to form a film; wherein, the modified graphene oxide accounts for 1% of the total volume of the composite membrane.

4) Preparing nano composite film containing europium ion nano cellulose/modified graphene oxide (TOCN-Eu/MGO), immersing the prepared TOCN/MGO composite film into 0.01M Eu (NO)₃)₃In solution for 1, 10, 100 or 1000 minutes to form a hydrogel film, then washed with distilled water and air-dried at room temperature to prepare a TOCN-Eu/MGO1 film, wherein MGO represents 1% of the total volume of the composite film.

The dielectric constant, dielectric loss and breakdown strength of the pure TOCN film prepared in the embodiment are tested by using an E4980AL-102LCR precision tester and a ZJC-50kV voltage breakdown tester, and the test result shows that the dielectric constant of the pure TOCN film prepared in the embodiment is about 158 at the frequency of 1 kHz, the dielectric loss is about 0.05 and the breakdown strength is only 257 kV/mm.

Example 3

3) Preparing a TOCN/modified graphene oxide composite membrane: blending the prepared TOCN dispersion liquid and modified graphene oxide according to the volume ratio of 98:2 (marked as TOCN-Eu/MGO1), then stirring magnetons of the mixed dispersion liquid for 30 min, performing ultrasonic treatment for 4 min, uniformly mixing, casting to form a film, and performing film formation at 40 DEG C^oC, drying in an oven to form a film; wherein, the modified graphene oxide accounts for 2% of the total volume of the composite membrane.

4) Preparing nano composite film containing europium ion nano cellulose/modified graphene oxide (TOCN-Eu/MGO), immersing the prepared TOCN/MGO composite film into 0.01M Eu (NO)₃)₃In solution for 1, 10, 100 or 1000 minutes to form a hydrogel film, then washed with distilled water and air-dried at room temperature to prepare a TOCN-Eu/MGO2 film, wherein MGO represents 2% of the total volume of the composite film.

The dielectric constant, dielectric loss and breakdown strength of the pure TOCN film prepared in the embodiment are tested by using an E4980AL-102LCR precision tester and a ZJC-50kV voltage breakdown tester, and the test result shows that the dielectric constant of the pure TOCN film prepared in the embodiment is about 189 at the frequency of 1 kHz, the dielectric loss is about 0.04 and the breakdown strength is only 330 kV/mm.

Example 4

3) Preparing a TOCN/modified graphene oxide composite membrane: mixing the prepared TOCN dispersion liquid with modified graphene oxide according to the volume ratio of 97:3 (marked as TOCN-Eu/MGO1), then stirring magnetons of the mixed dispersion liquid for 30 min, performing ultrasonic treatment for 4 min, uniformly mixing, casting to form a film, and performing film formation at 40 DEG C^oC, drying in an oven to form a film; wherein, the modified graphene oxide accounts for 3% of the total volume of the composite membrane.

4) Preparing nano composite film containing europium ion nano cellulose/modified graphene oxide (TOCN-Eu/MGO), immersing the prepared TOCN/MGO composite film into 0.01M Eu (NO)₃)₃In solution for 1, 10, 100 or 1000 minutes to form a hydrogel film, then washed with distilled water and air-dried at room temperature to prepare a TOCN-Eu/MGO3 film, wherein MGO represents 3% of the total volume of the composite film.

The dielectric constant, dielectric loss and breakdown strength of the pure TOCN film prepared in the embodiment are tested by using an E4980AL-102LCR precision tester and a ZJC-50kV voltage breakdown tester, and the test result shows that the dielectric constant of the pure TOCN film prepared in the embodiment is about 162 at the frequency of 1 kHz, the dielectric loss is about 0.07 and the breakdown strength is only 164 kV/mm.

Comparative example 1

A pure nanocellulose membrane (pure TOCN membrane) was prepared by the following procedure:

preparation of TOCN dispersion: taking 0.01 g of TEMPO and 0.01 g of sodium bromide, adding the TEMPO and the sodium bromide into 1000 ml of deionized water together, magnetically stirring for 10 min at the rotating speed of 500 r/min to fully and uniformly mix the TEMPO and the sodium bromide until the TEMPO and the sodium bromide are completely dissolved, adding 1 g of cotton linter into the system, adding 0.1 g of sodium hypochlorite into the system, dropwise adding 0.1 mol/L of sodium hydroxide solution into the system to keep the pH value of the system to be 9, reacting for 5 hours, filtering oxidized cellulose, fully washing for more than 3 times by using the deionized water, and drying to obtain TEMPO oxidized cellulose; and then placing the nano-crystalline cellulose into a beaker, adding deionized water for dispersion, then mechanically stirring for 6 min, and carrying out ultrasonic treatment for 12 min to finally obtain nano-crystalline cellulose dispersion with the concentration of 0.3%, namely 0.3% TOCN dispersion.

Preparation of pure TOCN films: the 0.3% TOCN dispersion was poured into a polystyrene petri dish at 40 deg.C^oAnd C, drying in an oven to obtain the product.

The appearance of the obtained TOCN dispersion liquid is tested by using a Nanosensors atomic force microscope, and the test result shows that the diameter of the TOCN obtained by the comparative example is 3-4 nm, and the average length is 3 mu m; the dielectric constant, the dielectric loss and the breakdown strength of the pure TOCN film prepared by the comparative example are tested by using an E4980AL-102LCR precision tester and a ZJC-50kV voltage breakdown tester, the test result shows that the dielectric constant of the pure TOCN film prepared by the comparative example is about 12 under the frequency of 1 kHz, the dielectric loss is about 0.04, the breakdown strength is only 15 kV/mm, the thermal stability performance is tested by using a Discovery TG thermogravimetric analyzer, and the test result shows that the temperature corresponding to the maximum decomposition rate of the pure TOCN film is 260^oC。

Comparative example 2

1) A pure nanocellulose membrane (pure TOCN membrane) was prepared by the following procedure:

2) Preparation of Modified Graphene Oxide (MGO)

20 mg of GO was added to 20 ml of anhydrous dimethylacetamide (DMAc), dispersed with stirring for 30 minutes, and then 0.2 g of HMDI was added and the mixture was stirred at 110 deg.C^oStirring for three hours under the condition of C.

3) Preparing a TOCN/modified graphene oxide composite membrane:

mixing the prepared TOCN dispersion liquid with modified graphene oxide at volume ratios of 99.5:0.5, 99:1, 98:2 and 97:3 (marked as TOCN-Eu/MGO1, TOCN-Eu/MGO2, TOCN-Eu/MGO3 and TOCN-Eu/MGO0.5), stirring the mixed dispersion liquid with magnetons for 30 min, performing ultrasonic treatment for 4 min, uniformly mixing, performing tape casting to form a film, and performing tape casting to form the film at 40^oC, drying in an oven to form a film; wherein the modified graphene oxide accounts for 0.5%, 1%, 2% and 3% of the total volume of the composite membrane.

The dielectric constant, dielectric loss and breakdown strength of the pure TOCN film prepared by the comparative example are tested by using an E4980AL-102LCR precision tester and a ZJC-50kV voltage breakdown tester, and the test result shows that the dielectric constant of the pure TOCN film prepared by the comparative example is about 78 at the frequency of 1 kHz, the dielectric loss is about 0.04 and the breakdown strength is only 89 kV/mm.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A preparation method of a nano composite film containing europium ion nano cellulose/modified graphene oxide is characterized by comprising the following steps:

1) preparing a nano-cellulose dispersion liquid TOCN:

dissolving 2,2,6, 6-tetramethylpiperidine-1-oxygen radical TEMPO and NaBr, then adding natural cellulose and NaClO, adjusting the pH value of the system to 9-11, carrying out oxidation reaction at 10-30 ℃ for 0.5-7 h, filtering, washing, drying, and finally dispersing in deionized water to form a nano-cellulose dispersion liquid;

2) preparing graft-modified graphene oxide MGO:

dispersing graphene GO in anhydrous dimethylacetamide (DMAc), adding HMDI, and stirring at 100-120 ℃ to prepare an HMDI modified graphene oxide solution;

3) preparing a TOCN/modified graphene oxide nano dispersion liquid:

2. The method for preparing a nanocomposite film according to claim 1, wherein in step 1), the TEMPO, NaBr, natural cellulose and NaClO are mixed in a mass ratio of 1: (1-10): (10-100): (10-100).

3. The method for preparing the nanocomposite film according to claim 1, wherein in the step 1), the natural cellulose is one or more of wood pulp, cotton cellulose, hemp fiber, coconut shell, bagasse, corn shell, wheat straw or rice cellulose; the dispersion is carried out by mechanical stirring or ultrasonic.

4. The method for preparing the nano composite film according to claim 1, wherein in the step 2), the mass ratio of the graphene to the HMDI is 1: (9-11).

5. The method for preparing a nano composite film according to claim 1, wherein in the step 3), the nano cellulose dispersion solution accounts for 97-99.5% by volume percentage, and the graphene oxide solution after HMDI modification accounts for 0.5-3% by volume percentage.

6. The method for preparing a nano composite film according to claim 1, wherein in the step 3), the mass concentration of the nano cellulose dispersion is 0.1-1%, wherein the diameter of the nano cellulose is 3-25 nm, and the length of the nano cellulose is 100-10 μm.

7. The method of claim 1, wherein in step 4), the Eu (NO) is used₃)₃The concentration of the solution is 0.005-0.02 mol/L.

8. The method for preparing a nanocomposite film according to claim 1, wherein the drying temperature in step 4) is 35 to 45%^oC。

9. The method for preparing a nanocomposite film according to claim 1, wherein in step 4), the immersion in Eu (NO)₃)₃The time in the solution is 1-1000 minutes.