A GO-g-BT / PVDF composite membrane, its preparation method and application

Abstract

The present invention relates to the field of dielectric thin film materials, and discloses a GO-g-BT / PVDF composite film, a preparation method thereof and an application thereof. The method includes: (1) subjecting GO-IPDI and 3-aminophenoxyphthalonitrile to a first contact reaction to obtain GO-CN; (2) subjecting barium titanate cyanide and the GO-CN to a second contact reaction in the presence of a catalyst; (3) subjecting a mixed solution containing polyvinylidene fluoride and the GO-g-BT filler to a film-forming treatment to obtain a GO-g-BT / PVDF composite film. The GO-g-BT / PVDF composite film provided by the present invention has a higher dielectric constant, energy storage density and breakdown strength, and can be widely applied to the field of dielectric thin film materials.

Description

Technical Field

[0001] The present invention relates to the field of dielectric thin film materials, and particularly to a GO-g-BT / PVDF composite film, a preparation method thereof, and an application thereof. Background Art

[0002] High-energy storage film capacitors have the characteristics of high energy storage density, fast charge and discharge speed, good chemical stability, high temperature resistance, etc., and play an important role in the power system. Among capacitor materials, polymers have become excellent candidate materials due to their high temperature resistance, low dielectric loss, fast charging speed, and low cost.

[0003] However, most polymers used in capacitors have low dielectric constants and energy storage densities, and need to be compounded with inorganic particles to obtain composite energy storage thin films with high energy storage density, high breakdown strength, and high dielectric constant. Among them, the compatibility between inorganic particles and polymers is the key to the performance of composite thin films, and chemical modification is a commonly used method to solve the interface compatibility problem.

[0004] CN102675779A discloses a high-dielectric constant three-phase composite material containing modified graphene. The three-phase composite material includes a polymer matrix polyvinylidene fluoride, and filler particles barium titanate and graphene particles modified by intrinsic polyaniline. Although this prior art has the advantages of high dielectric constant, good bonding performance, and simple preparation process, it cannot be applied in energy storage materials.

[0005] CN109942997A discloses a graphene oxide-barium titanate dielectric composite film and a preparation method thereof. The method includes: hydroxylating and aminating barium titanate with hydrogen peroxide and 3-aminopropyltrimethoxysilane in sequence to obtain aminated barium titanate powder, and then compounding BaTiO3-NH2 and graphene oxide in a DMF solution to obtain graphene oxide-barium titanate nanosheets; dissolving PVDF powder in DMF under ultrasonic conditions, ultrasonically mixing it with a uniform dispersion of GO-BT nanosheets in DMF until uniform, and then casting a film on a glass mold. The composite thin film prepared by this prior art can be used in high-performance dielectric energy storage devices such as wearable electronics, optoelectronic intelligent sensing, embedded capacitors, electric stress control, and high-power storage devices, but the filler particles are relatively low, there is no post-treatment, and the relative dielectric constant is low, making it difficult to obtain high-energy storage materials. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems of low energy storage density, breakdown strength, and dielectric constant existing in the dielectric thin films of the prior art.

[0007] To achieve the above purpose, in the first aspect of the present invention, a method for preparing a GO-g-BT / PVDF composite film is provided. The method includes:

[0008] (1) First, subject GO-IPDI and 3-aminophenoxyphthalonitrile to a first contact reaction to obtain GO-CN;

[0009] (2) In the presence of a catalyst, subject barium titanate cyanide and the GO-CN to a second contact reaction to obtain GO-g-BT filler; the weight ratio of the amounts of the GO-CN and the barium titanate cyanide used is 1:8 - 12;

[0010] (3) Subject a mixed solution containing polyvinylidene fluoride and the GO-g-BT filler to a film-forming treatment to obtain a GO-g-BT / PVDF composite film; the weight ratio of the amounts of the GO-g-BT filler and the polyvinylidene fluoride used is 1:1 - 6.

[0011] Preferably, in step (1), the first contact reaction is carried out under stirring conditions, and the conditions of the first contact reaction include: the stirring speed is 200 - 800 rpm, the temperature is 60 - 100 °C, and the time is 4 - 8 h.

[0012] More preferably, in step (1), in the first contact reaction, the weight ratio of the amounts of the GO-IPDI and the 3-aminophenoxyphthalonitrile used is 1:0.5 - 1.

[0013] Preferably, in step (2), the second contact reaction is carried out in the presence of a protective gas, and the conditions of the second contact reaction include: the temperature is 120 - 180 °C, and the time is 4 - 8 h.

[0014] Preferably, in step (2), in the second contact reaction, the weight ratio of the amounts of the GO-CN and the catalyst used is 1:4 - 8.

[0015] Preferably, in step (2), the method further includes preparing the barium titanate cyanide by an operation comprising the following steps:

[0016] S1: Under stirring, subject barium titanate and a hydrogen peroxide solution to a heating treatment to obtain an intermediate material;

[0017] S2: Mix and react 4-nitrophthalonitrile, potassium carbonate with the intermediate material to obtain the barium titanate cyanide.

[0018] Preferably, in step (3), the weight ratio of the amounts of the GO-g-BT filler and the polyvinylidene fluoride used is 1:2 - 4.

[0019] Preferably, in step (3), the film-forming treatment step includes: subjecting the mixed solution containing the polyvinylidene fluoride and the GO-g-BT filler to film-forming treatment successively under a first condition, a second condition, a third condition, a fourth condition, and a fifth condition;

[0020] The first condition includes: a temperature of 70 - 80 °C and a time of 1.5 - 2.5 h; the second condition includes: a temperature of 90 - 100 °C and a time of 1.5 - 2.5 h; the third condition includes: a temperature of 110 - 120 °C and a time of 1.5 - 2.5 h; the fourth condition includes: a temperature of 130 - 140 °C and a time of 1.5 - 2.5 h; the fifth condition includes: a temperature of 150 - 160 °C and a time of 1.5 - 2.5 h.

[0021] The second aspect of the present invention provides a GO-g-BT / PVDF composite membrane prepared by the method described in the first aspect.

[0022] The third aspect of the present invention provides the application of the GO-g-BT / PVDF composite membrane described in the second aspect in dielectric thin film materials.

[0023] The GO-g-BT / PVDF composite membrane provided by the present invention has a higher dielectric constant, a high energy storage density, and a high breakdown strength, and can be widely applied in the field of dielectric thin film materials. Detailed implementation manners

[0024] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0025] As described above, the first aspect of the present invention provides a method for preparing a GO-g-BT / PVDF composite membrane, and this method includes:

[0026] (1) Conduct a first contact reaction between GO-IPDI and 3-aminophenoxyphthalonitrile to obtain GO-CN;

[0027] (2) In the presence of a catalyst, conduct a second contact reaction between barium titanate cyanide and the GO-CN to obtain a GO-g-BT filler; the weight ratio of the GO-CN to the barium titanate cyanide is 1:8 - 12;

[0028] (3) Perform film-forming treatment on the mixed solution containing polyvinylidene fluoride and the GO-g-BT filler to obtain a GO-g-BT / PVDF composite membrane; the weight ratio of the GO-g-BT filler to the polyvinylidene fluoride is 1:1 - 6.

[0029] According to a preferred specific embodiment, in step (1), the preparation steps of the GO-IPDI include: under stirring and ultrasonic treatment (preferably, the stirring speed is 300 - 600 rpm and the ultrasonic power is 30 - 40 kW), add graphene oxide to dimethylacetamide, mix for 0.5 - 1.5 h, then add isophorone diisocyanate, and continue to mix and stir in an N2 atmosphere for 6 - 8 h to obtain a mixture; wash the mixture with acetone 3 - 5 times, and then dry it at 60 - 70 °C for 10 - 14 h to obtain the GO-IPDI.

[0030] Preferably, in step (1), in the preparation steps of the GO-IPDI, the conditions of the mixing and stirring include: the stirring speed is 300 - 600 rpm and the temperature is 50 - 55 °C.

[0031] More preferably, in step (1), in the preparation steps of the GO-IPDI, the dosage of the isophorone diisocyanate is 8 - 15 mL relative to each gram of the graphene oxide. Further preferably, in step (1), in the preparation steps of the GO-IPDI, the dosage of the dimethylacetamide is 50 - 80 mL relative to each gram of the graphene oxide.

[0032] Preferably, in step (1), in the preparation steps of the graphene oxide, the preparation steps of the graphene oxide include: in a water bath at 0 - 25 °C, mix graphite with concentrated sulfuric acid, concentrated phosphoric acid, and potassium permanganate, raise the water bath temperature to 45 - 55 °C and then stir (the stirring speed is 500 - 800 rpm) and perform ultrasonic treatment (the ultrasonic power is 30 - 40 kW) for 10 - 15 h, then add hydrogen peroxide to remove the unreacted potassium permanganate to obtain a reaction product; let the reaction product stand for 8 - 12 h, remove the supernatant to obtain a precipitate, wash the precipitate with hydrochloric acid and water in sequence until it is neutral, and then dry it at 60 - 80 °C for 18 - 26 h to obtain the graphene oxide.

[0033] Preferably, in step (1), the first contact reaction is carried out under stirring conditions, and the conditions of the first contact reaction include: the stirring speed is 200 - 800 rpm, the temperature is 60 - 100 °C, and the time is 4 - 8 h.

[0034] According to a preferred specific embodiment, in step (1), the steps of the first contact reaction include: under stirring and ultrasonic treatment (stirring speed is 300 - 600 rpm, ultrasonic power is 30 - 40 kW), adding the GO-IPDI into dimethylacetamide, mixing for 0.5 - 1.5 h, then adding 3-aminophenoxyphthalonitrile, and carrying out stirring and mixing in an N2 atmosphere to obtain a mixture; washing the mixture with acetone and dichloromethane 3 - 5 times in sequence, then carrying out suction filtration and drying treatment to obtain the GO-CN.

[0035] More preferably, in step (1), in the steps of the first contact reaction, the conditions of the stirring and mixing include: stirring speed is 300 - 600 rpm, temperature is 80 - 85 °C, and time is 5 - 6 h.

[0036] Further preferably, in step (1), in the steps of the first contact reaction, the dosage of dimethylacetamide is 50 - 80 mL relative to each gram of the GO-IPDI.

[0037] Particularly preferably, in step (1), in the first contact reaction, the weight ratio of the dosages of the GO-IPDI and the 3-aminophenoxyphthalonitrile is 1:0.5 - 1.

[0038] Preferably, in step (1), the preparation method of the 3-aminophenoxyphthalonitrile includes: under stirring, mixing and reacting 4-nitrophthalic dimethyl, 3-aminophenol and potassium carbonate to obtain 3-aminophenoxyphthalonitrile.

[0039] According to a preferred specific embodiment, in step (1), the preparation steps of the 3-aminophenoxyphthalonitrile further include: under stirring, adding 4-nitrophthalic dimethyl, 3-aminophenol and potassium carbonate into dimethylformamide, carrying out mixing reaction, then washing with acetone, water and ethanol in sequence to obtain a product, and carrying out suction filtration and drying treatment on the product to obtain the 3-aminophenoxyphthalonitrile.

[0040] More preferably, in step (1), in the preparation steps of the 3-aminophenoxyphthalonitrile, the weight ratio of the dosages of the 4-nitrophthalic dimethyl, the 3-aminophenol and the potassium carbonate is 1:0.4 - 0.7:0.6 - 1.

[0041] Further preferably, in step (1), in the preparation steps of the 3-aminophenoxyphthalonitrile, the dosage of dimethylformamide is 3 - 7 mL relative to each gram of the 4-nitrophthalic dimethyl.

[0042] Particularly preferably, in step (1), in the preparation step of the 3-aminophenoxyphthalonitrile, the conditions for the mixing reaction include: a stirring speed of 300-600 rpm, a temperature of 75-80 °C, and a time of 12-16 h.

[0043] Preferably, in step (2), the second contacting reaction is carried out in the presence of a protective gas, and the conditions for the second contacting reaction include: a temperature of 120-180 °C and a time of 4-8 h.

[0044] According to a preferred specific embodiment, in step (2), the process of the second contacting reaction includes: under stirring, adding barium titanate cyanide and the GO-CN into dimethylacetamide for mixing, then adding a catalyst, and carrying out a contacting reaction in an N2 atmosphere to obtain a reactant; washing the reactant with dimethylacetamide and water successively 3-5 times, and then carrying out suction filtration and drying treatment to obtain the GO-g-BT filler.

[0045] Preferably, the catalyst is copper chloride.

[0046] More preferably, in step (2), during the second contacting reaction, the conditions for the contacting reaction include: a stirring speed of 300-600 rpm, a temperature of 155-165 °C, and a time of 6-7 h.

[0047] Further preferably, the dosage of dimethylacetamide is 60-80 mL relative to each g of the GO-CN.

[0048] Particularly preferably, in step (2), in the second contacting reaction, the weight ratio of the dosages of the GO-CN and the catalyst is 1:4-8.

[0049] Preferably, in step (2), the method further includes an operation containing the following steps to prepare the barium titanate cyanide:

[0050] S1: Under stirring, heating barium titanate and a hydrogen peroxide solution to obtain an intermediate material;

[0051] S2: Mixing 4-nitrophthalonitrile, potassium carbonate with the intermediate material for a reaction to obtain the barium titanate cyanide.

[0052] More preferably, in step (2), the preparation step of the barium titanate cyanide further includes:

[0053] SS1: Under stirring and ultrasound (ultrasound power is 30 - 40 kW), mix barium titanate and hydrogen peroxide solution for 0.5 - 1.5 h, then carry out a reflux reaction in an oil bath to obtain a reaction product. After subjecting the reaction product to suction filtration, wash it with water and ethanol successively 3 - 5 times, and then dry it at 65 - 75 °C for 10 - 14 h to obtain an intermediate material;

[0054] SS2: Under stirring and ultrasound (ultrasound power is 30 - 40 kW), add the intermediate material to dimethylacetamide, mix for 0.5 - 1.5 h, then add 4 - nitrophthalonitrile and potassium carbonate, and carry out a mixing reaction in an N2 atmosphere to obtain a product. After subjecting the product to suction filtration, wash it with water and ethanol successively 5 - 8 times, and then dry it at 65 - 75 °C for 12 - 16 h to obtain the cyanated barium titanate.

[0055] Further preferably, in step (2), in the preparation step of the cyanated barium titanate, the conditions of the reflux reaction include: stirring speed is 200 - 400 rpm, and the time is 3 - 5 h; the conditions of the mixing reaction include: stirring speed is 300 - 600 rpm, the temperature is 75 - 85 °C, and the time is 6 - 7 h.

[0056] Particularly preferably, in step (2), in the preparation step of the cyanated barium titanate, the weight ratio of the amounts of the intermediate material, the 4 - nitrophthalonitrile, and the potassium carbonate is 1:0.1 - 0.4:0.1 - 0.4.

[0057] According to a preferred specific embodiment, in step (2), in the preparation step of the cyanated barium titanate, the amount of dimethylacetamide used is 20 - 40 mL relative to each g of the barium titanate.

[0058] Preferably, in step (3), the weight ratio of the amounts of the GO - g - BT filler and the polyvinylidene fluoride is 1:2 - 4. The inventors found that under this preferred embodiment, the GO - g - BT / PVDF composite membrane provided by the present invention has a higher dielectric constant and energy storage density.

[0059] Preferably, in step (3), the film - forming treatment step includes: subjecting the mixed solution containing the polyvinylidene fluoride and the GO - g - BT filler to film - forming treatment successively under the first condition, the second condition, the third condition, the fourth condition, and the fifth condition;

[0060] The first condition includes: temperature is 70 - 80 °C and time is 1.5 - 2.5 h; the second condition includes: temperature is 90 - 100 °C and time is 1.5 - 2.5 h; the third condition includes: temperature is 110 - 120 °C and time is 1.5 - 2.5 h; the fourth condition includes: temperature is 130 - 140 °C and time is 1.5 - 2.5 h; the fifth condition includes: temperature is 150 - 160 °C and time is 1.5 - 2.5 h.

[0061] According to a preferred specific embodiment, in step (3), the preparation process of the mixed solution includes:

[0062] S-1: Under ultrasonic wave (ultrasonic power is 30 - 40 kW), add the GO-g-BT filler into N,N-dimethylformamide and disperse and mix evenly for 1.0 - 1.5 h to obtain Material I;

[0063] S-2: Add polyvinylidene fluoride into N,N-dimethylformamide and carry out reflux stirring treatment to obtain Material II;

[0064] S-3: Ultrasonically mix (ultrasonic power is 30 - 40 kW) Material I and Material II for 2 - 3 h to obtain the mixed solution.

[0065] More preferably, in step (3), during the preparation process of the mixed solution, the conditions of the reflux stirring treatment include: stirring speed is 200 - 350 rpm and time is 1 - 1.5 h.

[0066] As described above, the second aspect of the present invention provides a GO-g-BT / PVDF composite membrane prepared by the method described in the first aspect above.

[0067] As described above, the third aspect of the present invention provides the application of the GO-g-BT / PVDF composite membrane described in the second aspect above in dielectric thin film materials.

[0068] The present invention will be described in detail below through examples.

[0069] In the following examples, unless otherwise specified, the experimental instruments, reagents and raw materials involved are all commercially available products, and the reagents are all analytical pure products.

[0070] In the present invention, unless otherwise specified, the room temperature means 25 ± 2 °C.

[0071] Raw materials

[0072] Barium titanate: average particle size is 60 nm, TPL Co., Ltd., USA;

[0073] Graphite: with an average particle size of 45 μm, purchased from Qingdao Yanxin Graphite Co., Ltd.;

[0074] Polyvinylidene fluoride: grade FR901, purchased from Shanghai 3F Co., Ltd.

[0075] In the following examples, the performance testing methods involved are as follows:

[0076] 1. The dielectric constant was tested using a Tonghui Electronics TH2819A LCR digital bridge meter. The test frequency range was 100 Hz - 1 MHz, and the test sample size was 10 mm × 10 mm;

[0077] 2. The breakdown voltage was tested using a Zhonghang Times Co., Ltd. ZJC - 50KV electric withstand voltage tester. The sample size was 5 cm × 5 cm, and the sample test was carried out in accordance with GB527 - 76;

[0078] 3. The energy storage density (Ue) was calculated based on the dielectric constant and the breakdown voltage: Ue = 0.5ε0ε r E b 2 , where ε0 is 8.85×10 -12 F / m, ε r is the dielectric constant, and E b is the breakdown strength.

[0079] Preparation Example 1

[0080] Under a water bath at 20 °C, with stirring and ultrasonic treatment (stirring speed of 500 rpm, ultrasonic power of 40 kW), 4 g of graphite was mixed with 450 mL of 98 wt% concentrated sulfuric acid, 54 mL of 85 wt% concentrated phosphoric acid, and 24 g of potassium permanganate. Then, the water bath temperature was raised to 50 °C, and after continuing to stir for 12 h, the temperature was lowered to room temperature; 800 mL of water and 8 mL of hydrogen peroxide were added to remove the unreacted potassium permanganate to obtain a reaction product; the reaction product was allowed to stand for 12 h, and the supernatant was removed to obtain a precipitate. The precipitate was washed repeatedly with 35 wt% hydrochloric acid and water until neutral, and then dried at 80 °C for 24 h to obtain graphene oxide.

[0081] Preparation Example 2

[0082] Under stirring and ultrasonic treatment (stirring speed of 300 rpm, ultrasonic power of 40 kW), 1 g of the graphene oxide obtained in Preparation Example 1 was added to 70 mL of dimethylacetamide and mixed for 1 h. Then, 10 mL of isophorone diisocyanate was added, and the mixture was continuously stirred in a N2 atmosphere for 7 h to obtain a mixture; the mixture was washed 3 times with acetone, then subjected to suction filtration, and dried at 70 °C for 12 h to obtain GO - IPDI;

[0083] Among them, the conditions for the mixing and stirring are: the stirring speed is 400 rpm, and the temperature is 50 °C.

[0084] Preparation Example 3

[0085] Under stirring, 17.3 g of 4-nitrophthalic dimethyl, 10.9 g of 3-aminophenol, and 13.8 g of potassium carbonate were added to 70 mL of dimethylformamide for a mixing reaction. Then, it was washed three times with acetone, water, and absolute ethanol in sequence to obtain a product. The product was subjected to suction filtration and dried at 70 °C for 12 h to obtain 3-aminophenoxyphthalonitrile;

[0086] Among them, the conditions for the mixing reaction are: the stirring speed is 300 rpm, the temperature is 75 °C, and the time is 12 h.

[0087] Preparation Example 4

[0088] (1) Under stirring and ultrasound (ultrasound power is 40 kW), 3 g of barium titanate and 80 mL of hydrogen peroxide solution were mixed for 1 h, and then reflux reaction was carried out in an oil bath to obtain a reaction product. The reaction product was subjected to suction filtration and then washed three times with water and absolute ethanol in sequence, and then dried at 75 °C for 12 h to obtain an intermediate material;

[0089] (2) Under stirring and ultrasound (ultrasound power is 40 kW), 3 g of the intermediate material was added to 100 mL of dimethylacetamide and mixed for 1 h. Then, 0.6 g of 4-nitrophthalonitrile and 1 g of potassium carbonate were added for a mixing reaction in an N2 atmosphere to obtain a product; the product was subjected to suction filtration and then washed five times with water and absolute ethanol in sequence, and then dried at 75 °C for 14 h to obtain cyanated barium titanate;

[0090] Among them, the conditions for the reflux reaction are: the stirring speed is 300 rpm, and the time is 4 h; the conditions for the mixing reaction are: the stirring speed is 400 rpm, the temperature is 80 °C, and the time is 6 h.

[0091] Example 1

[0092] This example is used to illustrate that the GO-g-BT / PVDF composite membrane of the present invention is prepared according to the formula and process parameters in Table 1 and the method described as follows.

[0093] The method for preparing the GO-g-BT / PVDF composite membrane includes the following steps:

[0094] (1) Under stirring and ultrasonic treatment (stirring speed: 300 rpm, ultrasonic power: 35 kW), GO-IPDI was added to 80 mL of dimethylacetamide and mixed for 1 h. Then, 3-aminophenoxyphthalonitrile was added, and the mixture was stirred and mixed in an N2 atmosphere to obtain a mixture. The mixture was washed three times with acetone and dichloromethane respectively, followed by suction filtration and drying at 70 °C for 20 h to obtain GO-CN;

[0095] (2) Under stirring, barium titanate cyanide and the obtained GO-CN were added to dimethylacetamide for mixing. Then, copper chloride was added, and a contact reaction was carried out in an N2 atmosphere to obtain a reactant. The reactant was washed three times with dimethylacetamide and water respectively, followed by suction filtration and drying at 80 °C for 24 h to obtain GO-g-BT filler;

[0096] (3) Under ultrasonic treatment (ultrasonic power: 35 kW), the obtained GO-g-BT filler was added to 16 mL of N,N-dimethylformamide and dispersed and mixed evenly for 1 h to obtain Material I. Polyvinylidene fluoride was added to 14 mL of N,N-dimethylformamide, and reflux stirring treatment was carried out to obtain Material II. Material I and Material II were mixed ultrasonically (ultrasonic power: 35 kW) for 3 h to obtain a mixed solution. The mixed solution was subjected to film-forming treatment on a clean plane under the first condition, the second condition, the third condition, the fourth condition, and the fifth condition in sequence, and then cooled to room temperature to obtain GO-g-BT / PVDF composite membrane S1;

[0097] The total amount of the GO-g-BT filler and the polyvinylidene fluoride was 2 g.

[0098] Example 2 and Example 3 were carried out using a process similar to that of Example 1, except that the formulation and process parameters for preparing the GO-g-BT / PVDF composite membrane were different. For details, see Table 1 (note: the parameters not listed in Table 1 are the same as the corresponding parameters in Example 1).

[0099] Table 1

[0100]

[0101] Example 4

[0102] This example was carried out using a method similar to that of Example 1. The difference was that in step (3), the total amount of the GO-g-BT filler and the polyvinylidene fluoride in this example was 2 g, and the weight ratio of the GO-g-BT filler to the polyvinylidene fluoride was 1:5.

[0103] The rest were the same as those in Example 1.

[0104] The GO-g-BT / PVDF composite membrane S4 was prepared.

[0105] Comparative Example 1

[0106] This comparative example was carried out according to a method similar to that of Example 1. The difference was that in step (2), the amount of GO-CN used in this comparative example was 1.2 g, and the weight ratio of the amount of GO-CN to the amount of cyanated barium titanate was 1:5.

[0107] The rest were the same as those in Example 1.

[0108] The graphene thermal conductive silicone grease DS1 was prepared.

[0109] Comparative Example 2

[0110] This comparative example was carried out according to a method similar to that of Example 1. The difference was that in step (3), the total amount of the GO-g-BT filler and the polyvinylidene fluoride used in this comparative example was 2 g, and the weight ratio of the amount of the GO-g-BT filler to the amount of the polyvinylidene fluoride was 1:20.

[0111] The rest were the same as those in Example 1.

[0112] The graphene thermal conductive silicone grease DS2 was prepared.

[0113] Comparative Example 3

[0114] This comparative example was carried out according to a method similar to that of Example 1. The difference was that in this comparative example, the GO-g-BT filler was not prepared, but GO-CN, cyanated barium titanate and polyvinylidene fluoride were directly mixed. Specifically, the method was as follows:

[0115] (1) GO-CN was prepared by the same operation as in step (1) of Example 1;

[0116] (2) Under ultrasound (ultrasound power was 35 kW), GO-CN and cyanated barium titanate were added to 16 mL of N,N-dimethylformamide and dispersed and mixed evenly for 1 h to obtain Material I; polyvinylidene fluoride was added to 14 mL of N,N-dimethylformamide and subjected to reflux stirring treatment to obtain Material II; Material I and Material II were ultrasonically mixed (ultrasound power was 35 kW) for 3 h to obtain a mixed solution; the mixed solution was subjected to film-forming treatment on a clean plane under the first condition, the second condition, the third condition, the fourth condition, and the fifth condition in sequence, and then cooled to room temperature to obtain the GO / BT / PVDF composite membrane DS3;

[0117] The total amount of GO-CN and cyanated barium titanate was 0.4 g, and the weight ratio of the amount of GO-CN to the amount of cyanated barium titanate was 1:10;

[0118] The dosage of the polyvinylidene fluoride is 1.6 g;

[0119] The conditions of the reflux stirring treatment are: the stirring speed is 350 rpm and the time is 1 h;

[0120] The first condition is: the temperature is 80 °C and the time is 2 h; the second condition is: the temperature is 100 °C and the time is 2 h; the third condition is: the temperature is 120 °C and the time is 2 h; the fourth condition is: the temperature is 140 °C and the time is 2 h; the fifth condition is: the temperature is 160 °C and the time is 2 h.

[0121] Test example

[0122] The performance of the composite membranes obtained in each of the examples and comparative examples was measured by the aforementioned test method, and the specific results are shown in Table 2.

[0123] Table 2

[0124]

[0125]

[0126] It can be seen from the results in Table 2 that the GO-g-BT / PVDF composite membrane prepared by the method of the present invention has higher dielectric constant, energy storage density and breakdown strength.

[0127] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing GO-g-BT / PVDF composite membrane, characterized in that, The method includes: (1) First contacting GO-IPDI with 3-aminophenoxyphthalonitrile to obtain GO-CN; (2) Second contacting barium titanate cyanide and the GO-CN in the presence of a catalyst to obtain GO-g-BT filler; the weight ratio of the amounts of the GO-CN and the barium titanate cyanide is 1:8 - 12; (3) Film-forming treatment is performed on a mixed solution containing polyvinylidene fluoride and the GO-g-BT filler to obtain a GO-g-BT / PVDF composite film; the weight ratio of the amounts of the GO-g-BT filler and the polyvinylidene fluoride is 1:2 - 4.

2. The method according to claim 1, wherein In step (1), the first contact reaction is carried out under stirring conditions, and the conditions of the first contact reaction include: the stirring speed is 200 - 800 rpm, the temperature is 60 - 100 °C, and the time is 4 - 8 h.

3. The method according to claim 1 or 2, characterized in that, In step (1), in the first contact reaction, the weight ratio of the amounts of the GO-IPDI and the 3-aminophenoxyphthalonitrile is 1:0.5 - 1.

4. The method according to claim 1 or 2, characterized in that In step (2), the second contact reaction is carried out in the presence of a protective gas, and the conditions of the second contact reaction include: the temperature is 120 - 180 °C, and the time is 4 - 8 h.

5. The method according to claim 1 or 2, characterized in that, In step (2), in the second contact reaction, the weight ratio of the amounts of the GO-CN and the catalyst is 1:4 - 8.

6. The method according to claim 1 or 2, characterized in that, In step (2), the method further includes preparing the barium titanate cyanide by an operation containing the following steps: S1: Under stirring, heating barium titanate and a hydrogen peroxide solution to obtain an intermediate material; S2: Mixing and reacting 4-nitrophthalonitrile, potassium carbonate with the intermediate material to obtain the barium titanate cyanide.

7. The method according to claim 1 or 2, characterized in that, In step (3), the steps of the film-forming treatment include: performing film-forming treatment on the mixed solution containing the polyvinylidene fluoride and the GO-g-BT filler under the first condition, the second condition, the third condition, the fourth condition, and the fifth condition in sequence; The first condition includes: the temperature is 70 - 80 °C, and the time is 1.5 - 2.5 h; the second condition includes: the temperature is 90 - 100 °C, and the time is 1.5 - 2.5 h; the third condition includes: the temperature is 110 - 120 °C, and the time is 1.5 - 2.5 h; the fourth condition includes: the temperature is 130 - 140 °C, and the time is 1.5 - 2.5 h; the fifth condition includes: the temperature is 150 - 160 °C, and the time is 1.5 - 2.5 h.

8. The GO-g-BT / PVDF composite film prepared by the method according to any one of claims 1 - 7.

9. The application of the GO-g-BT / PVDF composite film according to claim 8 in dielectric and energy storage thin film materials.

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