LU501683B1

LU501683B1 - Cyanoethyl cellulose-based high-dielectric nano composite film and preparation method thereof

Info

Publication number: LU501683B1
Application number: LU501683A
Authority: LU
Inventors: Minghua Wang; Yudong Bi; yalong Wang; Feijun Wang; Houyu Liu; Ziqiang Shao
Original assignee: Beijing Institute Tech; Shandong Head Co Ltd
Priority date: 2022-03-18
Filing date: 2022-03-18
Publication date: 2022-09-19

Abstract

The present invention relates to a cyanoethyl cellulose-based high-dielectric nano composite film and a preparation method thereof and aims to provide a degradable high-dielectric flexible nano composite film with high dielectric constant, low dielectric loss, good mechanical properties and excellent thermal performance, and a preparation method thereof. The composite film is prepared by the following steps: preparing a solution from cyanoethyl cellulose as a base, graphene as a filler and montmorillonite as a dispersant by using a solvent, and forming the film by casting. The cyanoethyl cellulose for preparing the high-dielectric flexible nano composite film is a renewable source; the composite film is high in dielectric performance and low in dielectric loss, applicable to electronics, motor and cable industries and promising in the fields of artificial muscle, wave-absorbing materials and drug slow release; the production method is safe, the process is simple, and the production cost is low.

Description

CYANOETHYL CELLULOSE-BASED HIGH-DIELECTRIC NANO LUS01683

COMPOSITE FILM AND PREPARATION METHOD THEREOF TECHNICAL FIELD

[01] The present invention relates to a high-dielectric material and a preparation method thereof, in particular to a cyanoethyl cellulose-based high-dielectric nano composite film and a preparation method thereof.

BACKGROUND ART

[02] A high-dielectric material is a material having a very extensive application prospect. With the development of numerous important electronic devices such as capacitors, resonators, filters and memories towards high performance and miniaturization, polymer-based nano composites with high dielectric constants have been valued by more and more researchers. Polymers are often used for energy storage because of their high breakdown strength, low dielectric loss, good processability and low cost. However, the dielectric constants of general polymers are low, so how to improve the dielectric performance of polymers on the basis of retaining their original good properties has become an important topic.

[03] Many systems have been developed by researchers in order to improve the dielectric performance of polymer-based composites. One simple method is to add a ceramic filler with a high dielectric constant to a polymer matrix, but with this method, it is difficult to obtain a composite with a dielectric constant of higher than 100 even by adding a high content of ceramic filler, and a high filler content will enable the composite to have a high mass density, more holes and a poor flexibility. Another common method is to add to a polymer matrix a conductive filler such as carbon nanotubes, carbon black, graphene, carbon fiber, metal particles and the like. Among these conductive fillers, graphene has attracted more attention because of its extremely high specific surface area and excellent optical, electrical, thermal and mechanical properties as well as its lower percolation threshold in composites. According to a percolation theory, when an addition amount of graphene is close to its percolation threshold, a dielectric constant of a composite can be significantly increased. However, due to a powerful Van Der Waals force between graphene sheets, the graphene sheets are very easy to aggregate, resulting in poor dispersion in the composite.

[04] Preparation of a cyanoethyl cellulose/graphene composite from cyanoethyl cellulose as a base was reported in CN201310089200.4. But the preparation method is complicated, and in-situ reduction with highly corrosive hydrogen iodide causes a great corrosion damage to the surface of the composite. In order to improve a dispersivity and compatibility of graphene in a base, there are two comparatively effective methods. One is a physical method, i.e. dispersing graphene through an electrostatic action and improving the compatibility of graphene, so as to improve a dielectric constant of graphene; another method is a chemical method, i.e. covalently modifying the surface of graphene and introducing polymer chains to the surface of graphene, so as to inhibit an agglomeration between graphene sheets. However, a chemical preparation process is relatively complex, while the physical method is relatively simple in operation and can 1 be regarded as an efficient approach. In order to improve the dispersivity of the nano LU501683 filler in the base, CN104672502A invented a method for dispersing carbon nanotubes using barium titanate nano particles, which can prove that the physical method can effectively improve the dispersivity and compatibility of the nano filler in the base and obtain a nano composite with a high dielectric constant.

[05] Currently, a base of a polymer-based high-dielectric composite is mainly prepared from polyvinylidene fluoride (PVDF) copolymer, polyimide, epoxy resin, polyethylene, polymethylmethacrylate and the like as bases through doping and compounding of ceramic, metal or organic semiconductors. A dielectric constant of common polymer bases is less than 5 except that a dielectric constant of polyvinylidene fluoride and its copolymer is greater than 5. CN201410638440.X and CN201210179758.7 disclosed a graphene/polymer-based high-dielectric material, but common polymer bases such as PVDF are difficult to degrade, and raw materials are nonrenewable. Therefore, it is an inevitable trend to prepare a new, widely sourced and biodegradable high-dielectric-constant composite.

[06] Cellulose is a natural polymer most widely distributed and reserved in the largest amount in nature, and has the advantages of complete degradation, no pollution and good biocompatibility. It is an inexhaustible renewable resource and is recognized as a future energy and chemical material. Cellulose derivatives inherit the biocompatibility and degradability of cellulose. Cyanoethyl cellulose (CEC) is a cellulose ether with a high dielectric constant generally above 10. CEC with a high degree of substitution also features high water resistance, high insulation, self-extinguishment and the like. High-dielectric materials prepared from CEC as a base have a wide application prospect in the field of bioengineering because of their good dielectric properties and good biocompatibility.

SUMMARY

[07] The present invention is intended to provide a degradable high-dielectric flexible nano composite film with high dielectric constant, low dielectric loss, good mechanical properties and excellent thermal performance, and a preparation method thereof.

[08] To achieve the above-mentioned purpose, the technical solution used herein is that: a cyanoethyl cellulose-based high-dielectric nano composite film includes the following components based on parts by weight: 10 parts of cyanoethyl cellulose,

0.1-1.5 parts of graphene, and 300-500 parts of solvent, the nano composite film is prepared by the following steps: preparing a solution from the cyanoethyl cellulose as a base, the graphene as a filler and montmorillonite as a dispersant by using the solvent, and forming the film by casting.

[09] Further, the nano composite film includes the following components based on parts by weight: 10 parts of cyanoethyl cellulose, 1 part of graphene, and 400 parts of solvent.

[10] Further, the degree of substitution of the cyanoethyl cellulose is 2.4-2.6.

[11] Further, the carbon-oxygen ratio of the graphene is 7-18.

[12] Further, the solvent is any one of N,N-dimethylformamide, 2

N,N-dimethylacetamide and N-methylpyrrolidone. LU501683

[13] Further, the thickness of the dried composite film is 0.030-0.100 mm.

[14] The method for preparing the cyanoethyl cellulose-based high-dielectric nano composite film includes the following steps:

[15] A. Preparing graphene oxide: preparing graphene oxide by a Hummers method,

[16] B. Reducing graphene oxide: reducing graphene oxide prepared in step A by a microwave method or heating method, wherein the microwave method includes the following steps: ultrasonically dispersing 10 parts of graphene oxide into a solvent, adding 0.01 part of reductant, placing the reaction mixture in a microwave reactor for a reduction reaction at a power of 100-800 W and a temperature of 40-60°C for a reaction time of 5-20 min, and obtaining reduced graphene oxide through centrifugation, washing and drying after the end of the reaction;

[17] Reduction by the heating method includes the following steps: reducing graphene oxide at 980-1000°C for 30 s;

[18] C. Preparing a composite film: dissolving 10 parts of cyanoethyl cellulose in 300 parts of solvent, dispersing 0.5-2 parts of graphene and 0.1-1 part of montmorillonite into 100 parts of solvent, adding the latter solution to a cyanoethyl cellulose solution while stirring to prepare a casting solution, pouring the casting solution onto a culture dish with a smooth surface, forming a film by casting, then placing the film into an oven and drying the film at 50-60°C to obtain the composite film.

[19] Further, the reductant is phenylhydrazine or hydrazine hydrate. That is to say, both reductants can be used for the method for preparing the high-dielectric flexible nano composite film described herein.

[20] Further, the solvent in the method for preparing the cyanoethyl cellulose-based high-dielectric nano composite film is one of water, N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

[21] The preparation of the high-dielectric flexible nano composite film by the method of the present invention has the following advantages:

[22] 1. The raw material for preparing cyanoethyl cellulose is an inexhaustible and renewable resource because of its extensive sources, complete biodegradability and non-pollution.

[23] 2. The cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film prepared is high in dielectric performance and low in dielectric loss, applicable to electronics, motor and cable industries and promising in the fields of artificial muscle, wave-absorbing materials and drug slow release.

[24] 3. The cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film prepared has a glossy surface, beautiful appearance and certain flexibility.

[25] 4. The cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film prepared has good mechanical and thermal properties.

[26] 5. The production method of the cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film prepared is safe, the process is simple, the production cost is low, so that the film has a promising market prospect.

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[27] ©. The dielectric constant of the cyanoethyl cellulose/graphene/montmorillonite LU501683 flexible high-dielectric nano composite film prepared is higher than that without montmorillonite. For example, when all contents of graphene sheets are 5%, the dielectric constants of the cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film prepared are 39.6 and 21.9 respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

[28] FIG 1 is a digital photo taken 5 days after graphene and graphene/montmorillonite were respectively dispersed in DMF and kept still.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[29] The present invention will be further described below in association with the specific embodiments. The embodiments described are only the preferred embodiments of the present invention and are not intended to limit the present invention. Various alterations and changes of the present invention are possible for those skilled in the art. Any and all modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present invention shall be included in the scope of protection of the present invention. In examples I to IV, the dielectric performance of the product was determined by Agilent 4294A Impedance Analyzer, and a thermal stability was determined by TG-DTA 6200LAB SYS Thermogravimetry/Differential Thermal Simultaneous Thermal Analyzer.

[30] In FIG 1, flask a, i.e. the flask on the left, is a photo of graphene 5 days after being dispersed in DMF and kept still, flask b, i.e. the flask on the right, is a photo of graphene/montmorillonite 3 days after being dispersed in DMF and kept still, and it is intuitively obvious that the dispersion effects of graphene in the two photos are completely different, and the dispersion effect of the latter is much better than that of the former.

[31] Example I

[32] 0.6 g of cyanoethyl cellulose was dissolved in 20 g of DMF, magnetically stirred for 2 h and dissolved. 0.006 g of graphene and 0.06 g of montmorillonite were ultrasonically dispersed into 20 g of DMF, stirred for 1 h, and ultrasonically dispersed for 6 h. A dispersed graphene/montmorillonite suspension was added to a solution of cyanoethyl cellulose to obtain a mixed solution, and the mixed solution was magnetically stirred for 4 h and ultrasonically dispersed for 4 h. A film-forming solution was poured into a watch glass, placed into an oven, dried at 60°C for around 48 h and cooled, then the film was uncovered to obtain the cyanoethyl cellulose/graphene/montmorillonite high-dielectric flexible nano composite film.

[33] The cyanoethyl cellulose-based high-dielectric flexible nano composite film prepared from such components based on weight grams has the property that: the dielectric constant and dielectric loss are respectively 27.0 and 0.46 (100 Hz), the thermal decomposition temperature is 327°C.

[34] Example II

[35] 0.6g of cyanoethyl cellulose was dissolved in 20 g of DMF, magnetically stirred for 2 h and dissolved. 0.03 g of graphene and 0.06 g of montmorillonite were 4 ultrasonically dispersed in 20 g of DMF, stirred for 1 h, and ultrasonically dispersed for LU501683 6 h. A dispersed graphene/montmorillonite suspension was added to a solution of cyanoethyl cellulose to obtain a mixed solution, and the mixed solution was magnetically stirred for 4 h and ultrasonically dispersed for 4 h. A film-forming solution was poured into a watch glass, placed into an oven, dried at 60°C for around 48 h and cooled, then the film was uncovered to obtain the cyanoethyl cellulose/graphene/montmorillonite high-dielectric flexible nano composite film.

[36] The cyanoethyl cellulose-based high-dielectric flexible nano composite film prepared from such components based on weight grams has the property that: the dielectric constant and dielectric loss are respectively 39.6 and 0.047 (100 Hz); the thermal decomposition temperature is 319.3°C.

[37] Example III

[38] 0.6g of cyanoethyl cellulose was dissolved in 20 g of DMF, magnetically stirred for 2 h and dissolved. 0.042 g of graphene and 0.06 g of montmorillonite were ultrasonically dispersed in 20 g of DMF, stirred for 1 h, and ultrasonically dispersed for 6 h. A dispersed graphene/montmorillonite suspension was added to a solution of cyanoethyl cellulose to obtain a mixed solution, and the mixed solution was magnetically stirred for 4 h and ultrasonically dispersed for 4 h. A film-forming solution was poured into a watch glass, placed into an oven, dried at 60°C for around 48 h and cooled, then the film was uncovered to obtain the cyanoethyl cellulose/graphene/montmorillonite high-dielectric flexible nano composite film.

[39] The cyanoethyl cellulose-based high-dielectric flexible nano composite film prepared from such components based on weight grams has the property that: the dielectric constant and dielectric loss are respectively 62.7 and 0.073 (100 Hz); the thermal decomposition temperatures are 266.6°C and 315.6°C.

[40] Example IV

[41] A cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film had components and weight grams of 0.6 g of cyanoethyl cellulose,

0.072 g of thermally reduced graphene, and 0.036 g of montmorillonite.

[42] 0.6 g of cyanoethyl cellulose was dissolved in 20 g of DMF, magnetically stirred for 2 h and dissolved. 0.072 g of graphene and 0.06 g of montmorillonite were ultrasonically dispersed in 20 g of DMF, stirred for 1 h, and ultrasonically dispersed for 6 h. Dissolved polyacrylonitrile grafting modified graphene was added to a solution of cyanoethyl cellulose to obtain a mixed solution, and the mixed solution was magnetically stirred for 4 h and ultrasonically dispersed for 4 h. A film-forming solution was poured into a watch glass, placed into an oven, dried at 60°C for around 48 h and cooled, then the film was uncovered to obtain the cyanoethyl cellulose/graphene/montmorillonite high-dielectric flexible nano composite film.

[43] The cyanoethyl cellulose-based high-dielectric flexible nano composite film prepared from such components based on weight grams has the property that: the dielectric constant and dielectric loss are respectively 912 and 17 (100 Hz); the thermal decomposition temperature is 313.3 °C.

[44] Example V

[45] 0.6g of cyanoethyl cellulose was dissolved in 20 g of DMF, magnetically stirred for 2 h and dissolved. 0.03 g of graphene and 0.06 g of montmorillonite were LU501683 ultrasonically dispersed in 20 g of DMEF, stirred for 1 h, and ultrasonically dispersed for 6 h. A dispersed graphene/montmorillonite suspension was added to a solution of cyanoethyl cellulose to obtain a mixed solution, and the mixed solution was magnetically stirred for 4 h and ultrasonically dispersed for 4 h. A film-forming solution was poured into a watch glass, placed into an oven, dried at 60°C for around 48 h and cooled, then the film was uncovered to obtain the cyanoethyl cellulose/graphene/montmorillonite high-dielectric flexible nano composite film.

[46] The cyanoethyl cellulose-based high-dielectric flexible nano composite film prepared from such components based on weight grams has the property that: the dielectric constant and dielectric loss are respectively 30.01 and 0.404 (100Hz).

[47] Example VI

[48] A cyanoethyl cellulose/graphene/montmorillonite flexible high-dielectric nano composite film was prepared from 0.6 g of cyanoethyl cellulose, 0.06 g of microwave-reduced graphene, and 0.06g of montmorillonite.

[49] 0.6g of cyanoethyl cellulose was dissolved in 20 g of DMF, magnetically stirred for 2 h and dissolved. 0.06 g of graphene and 0.06 g of montmorillonite were ultrasonically dispersed in 20 g of DMEF, stirred for 1 h, and ultrasonically dispersed for 6 h. A dispersed graphene/montmorillonite suspension was added to a solution of cyanoethyl cellulose to obtain a mixed solution, and the mixed solution was magnetically stirred for 4 h and ultrasonically dispersed for 4 h. A film-forming solution was poured into a watch glass, placed into an oven, dried at 60°C for around 48 h and cooled, then the film was uncovered to obtain the cyanoethyl cellulose/graphene/montmorillonite high-dielectric flexible nano composite film.

[50] The cyanoethyl cellulose-based high-dielectric flexible nano composite film prepared from such components based on weight grams has the property that: the dielectric constant and dielectric loss are respectively 110.1 and 0.75 (100 Hz).

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Claims

WHAT IS CLAIMED IS: LUs01683

1. A cyanoethyl cellulose-based high-dielectric nano composite film, comprising the following components based on parts by weight: 10 parts of cyanoethyl cellulose,

0.1-1.5 parts of graphene, and 300-500 parts of solvent, the composite film is prepared by the following steps: preparing a solution from the cyanoethyl cellulose as a base, the graphene as a filler and montmorillonite as a dispersant by using the solvent, and forming the film by casting.

2. The nano composite film of claim 1, wherein the nano composite film comprises the following components based on parts by weight: 10 parts of cyanoethyl cellulose,

0.1-1 part of graphene, and 300-500 parts of solvent.

3. The nano composite film of claim 1 or 2, wherein the degree of substitution of the cyanoethyl cellulose is 2.4-2.6.

4. The nano composite film of claim 1 or 2, wherein the carbon-oxygen ratio of the graphene is 7-18.

5. The nano composite film of claim 1 or 2, wherein the solvent is any of N,N- dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

6. The nano composite film of claim 1 or 2, wherein the thickness of the dried composite film is 0.030-0.100 mm.

7. A method for preparing the cyanoethyl cellulose-based high-dielectric nano composite film of any of claims 1-6, comprising the following steps: A. Preparing graphene oxide: preparing graphene oxide by a Hummers method; B. Reducing graphene oxide: reducing graphene oxide prepared in step A by a microwave method or heating method, wherein the microwave method includes the following steps: ultrasonically dispersing 10 parts of graphene oxide into the solvent, adding 0.01 part of reductant, placing the reaction mixture in a microwave reactor for a reduction reaction at a power of 100-800 W and a temperature of 40-60°C for a reaction time of 5-20 min, and obtaining reduced graphene oxide through centrifugation, washing and drying upon completion of the reaction; Reduction by the heating method includes the following steps: reducing graphene oxide at 980-1,000°C for 30 s; and C. Preparing a composite film: dissolving 10 parts of cyanoethyl cellulose in 300 parts of solvent, dispersing 0.1-1 part of graphene and 0.1-1 part of montmorillonite into 100 parts of solvent, adding the latter solution to a cyanoethyl cellulose solution under stirring to prepare a casting solution, pouring the casting solution onto a culture dish with a smooth surface, forming a film by casting, then placing the film into an oven and drying the film at 50-60°C to obtain the composite film.

8. The method for preparing the nano composite film of claim 7, wherein the reductant is phenylhydrazine or hydrazine hydrate.

9. The method for preparing the nano composite film of claim 7, wherein the solvent is one of water, N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

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