CN112980191A

CN112980191A - Preparation method of nickel-plated carbon nanotube enhanced PDMS composite film conductive performance and product thereof

Info

Publication number: CN112980191A
Application number: CN202110153920.7A
Authority: CN
Inventors: 向珊
Original assignee: Southwest Jiaotong University
Current assignee: Southwest Jiaotong University
Priority date: 2021-02-04
Filing date: 2021-02-04
Publication date: 2021-06-18

Abstract

The invention discloses a preparation method of a nickel-plated carbon nanotube reinforced PDMS composite film with conductive performance and a product thereof, belonging to the technical field of nickel-plated carbon nanotube reinforced polymer composite materials, wherein the preparation method comprises the following steps: pretreating the carbon nano tube to prepare an oxidized carbon nano tube; nickel plating is carried out on the oxidized carbon nanotube by a chemical deposition method to prepare the MWCNT-Ni composite material; the MWCNT-Ni composite material is dispersed in a PDMS matrix through a solvent method to prepare a PDMS/MWCNT/Ni composite film; the invention takes the nickel-plated carbon nano tube as the filler of the polymer composite material, shows more excellent dispersibility in the PDMS matrix than the pure carbon nano tube, and improves the conductivity to a certain extent.

Description

Preparation method of nickel-plated carbon nanotube enhanced PDMS composite film conductive performance and product thereof

Technical Field

The invention belongs to the technical field of nickel-plated carbon nanotube reinforced polymer composite materials, and particularly relates to a preparation method of a nickel-plated carbon nanotube reinforced PDMS composite film with conductive performance and a product thereof.

Background

In recent years, the development of novel multi-component composites in which conductive nanomaterials are incorporated into a polymer matrix has been an attractive subject of research, such as silicone Polymers (PDMS) that can achieve excellent stretchability and high conductivity by filling with nano-conductive particles. Various nanofillers include metal particles, carbon-containing derivative materials (carbon black (CB), graphene, carbon fibers, carbon nanotubes), metal fibers, etc., and carbon nanotubes are very attractive due to their high electrical conductivity and excellent aspect ratio, and are often used as ideal composite additives, and a flexible thin film material with uniform structure, high electrical conductivity and stable performance can be prepared by uniformly dispersing carbon nanotubes in a PDMS matrix.

However, the carbon nanotube bundles are highly polarized inside and have smooth walls, and in carbon nanotube reinforced nanocomposites, the original MWCNTs tend to aggregate into bundles, resulting in a high degree of anisotropy of the composite and thus impairing its performance. Therefore, controlling the effective dispersion of MWCNTs in a polymer matrix is one of the key issues.

In addition to having strong cohesive force, the smooth sidewall of the carbon nanotube causes very weak interfacial interaction between the carbon nanotube and the polymer matrix, and the polymer is easily slipped along the surface of the carbon nanotube, which also seriously affects the performance of the composite material.

Therefore, when the MWCNT is used as the conductive filler to prepare the nano polymer composite material, the technical problems that the MWCNT is easy to agglomerate and tangle in a polymer matrix and the interface between the MWCNT and the polymer matrix is weaker are solved, and a preparation method for enhancing the conductivity of the PDMS composite film by using the nickel-plated carbon nanotube and a product thereof need to be researched.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method of a nickel-plated carbon nanotube enhanced PDMS composite film with conductive performance and a product thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of nickel-plated carbon nanotube enhanced PDMS composite film conductive performance comprises the following steps:

1) pretreating the carbon nano tube to prepare an oxidized carbon nano tube;

2) nickel plating is carried out on the oxidized carbon nanotube by a chemical deposition method to prepare the MWCNT-Ni composite material;

3) the MWCNT-Ni composite material is dispersed in a PDMS matrix through a solvent method to prepare a PDMS/MWCNT/Ni composite film.

Further, in step 1), the preparation method of the oxidized carbon nanotube comprises: placing the carbon nano tube in absolute ethyl alcohol to prepare a dispersion liquid, crushing the carbon nano tube in the dispersion liquid through ultrasonic crushing treatment, then carrying out suction filtration and washing, placing the crushed carbon nano tube in a nitric acid solution for oxidation treatment, finally washing the carbon nano tube to be neutral through deionized water, and drying the carbon nano tube to obtain the carbon nano tube. All subsequent steps of washing to be neutral by deionized water are convenient for the subsequent steps to be carried out, and the negative influence of pH is reduced.

Further, in the step 1), the adjusting power of the ultrasonic crushing treatment is 200-300W, and the time of the ultrasonic crushing treatment is 30-60 min; the concentration of nitric acid in the nitric acid solution is 4-5.6mol/L, the concentration of the carbon nano tube in the dispersion liquid is 0.15-0.3g/L, the reaction temperature of the oxidation treatment is 70-85 ℃, the reaction time of the oxidation treatment is 1-2h, and the concentration of the carbon nano tube in the nitric acid solution is 0.15-0.3 g/L. The steps of the ultrasonic crushing treatment in the parameters belong to the original technical scheme, the technical parameters are reasonable and feasible, and the carbon nano tubes are promoted to be better dispersed in the solution by carrying out the ultrasonic pre-crushing treatment on the carbon nano tubes, so that the subsequent uniform deposition of the Sn-Pd active sites is facilitated. If technical parameters which are not in the range are used, for example, if the ultrasonic power is too high, more defects are generated on the carbon nanotubes, the material performance is affected, and if the power is too low, a good dispersion effect cannot be achieved.

Further, in the step 2), the preparation method of the MWCNT-Ni composite material comprises the following steps: and (2) carrying out sensitization reaction and activation reaction on the carbon oxide nano tube in sequence, uniformly dispersing the carbon oxide nano tube subjected to the activation reaction in a chemical plating solution, carrying out chemical nickel plating, washing the carbon oxide nano tube to be neutral by deionized water, and drying the carbon oxide nano tube to obtain the carbon oxide nano tube.

Further, in the step 2), the sensitizing solution in the sensitization reaction is SnCl₂-HClMixed solution of SnCl₂The concentration of (A) is 15-20g/L, SnCl₂The molar ratio of HCl to HCl is 1: 3-5; the temperature of the sensitization reaction is 40-50 ℃, the time of the sensitization reaction is 30-45min, and the concentration of the oxidized carbon nano tube in the sensitization liquid is 0.45-0.65 g/L; the activating solution in the activation reaction is PdCl₂HCl solution, in which PdCl₂The concentration of (A) is 1-1.5g/L, PdCl₂The mol ratio of the carbon nano tube to HCl is 1:100-120, the temperature of the activation reaction is 40-50 ℃, the time of the activation reaction is 30-45min, and the concentration of the carbon nano tube oxide in the activation solution is 0.45-0.65 g/L; the carbon oxide nanotubes after the sensitization reaction and the activation reaction are repeatedly washed to be neutral by deionized water and dried. The mass concentration and the reaction time of sensitization and activation related to the parameters are the original parameter ranges of the scheme, the proper quantity of Sn-Pd nuclei can be obtained through regulating and controlling the mass concentration and the reaction time and can be used as active sites, the effect of controlling and optimizing the plating layer can be achieved, and if the technical parameters which are not in the ranges are used, the nickel layer is discontinuously distributed and seriously accumulated, and the quality of the plating layer is influenced.

Further, step 2), the chemical plating solution comprises NiCl₂·6H₂O、H₂NNH₂·H₂O, aminoacetic acid, boric acid and deionized water, wherein NiCl₂·6H₂O concentration of 11.87-13.87g/L, H₂NNH₂·H₂The concentration of O is 20-23g/L, the concentration of glycine is 22.5-24.5g/L, and the concentration of boric acid is 30.9-32.9 g/L; the concentration of the carbon oxide nano tube after the activation reaction in the chemical plating solution is 0.45-0.65 g/L. The formula and concentration parameters of the whole plating solution related to the parameters are the original parameter range of the scheme, the scheme uses the hydrazine reduction method to prepare the nickel-plated carbon nano tube, the purity of the generated plating layer is high, the bonding force is good, and if the technical parameters which are not in the range are used, by-products such as Ni-P, Ni-B and the like are generated if other reducing agents (sodium hypophosphite and potassium borohydride) are replaced, so that the plating efficiency and the plating quality are influenced.

Further, in the step 2), the chemical plating solution is adjusted to pH 10.5-12.5 by using potassium hydroxide; the temperature of the chemical nickel plating is 85-90 ℃, and the time of the chemical nickel plating is 15-30 min. The pH range and the nickel plating temperature related in the parameters are the original parameter range of the scheme, the nickel plating reaction can be normally carried out in the range, a certain reaction rate is maintained, and a uniform and high-quality metal nickel plating layer is obtained.

Further, in the step 3), the preparation method of the PDMS/MWCNT/Ni composite film comprises: putting the MWCNT-Ni composite material into an ethanol solution, performing ultrasonic dispersion to obtain MWCNT-Ni suspension, then adding PDMS, heating and stirring, volatilizing ethanol to obtain a scorched black mixture, then cooling to room temperature, adding a curing agent, stirring, removing bubbles in vacuum at normal temperature, and finally heating, curing and molding to obtain the MWCNT-Ni composite material. This step was sonicated using a sonicator. And transferring the mixture subjected to bubble removal in vacuum into a square mold with the size of 3cm by 0.2mm, heating for curing and molding, and peeling to obtain the PDMS/MWCNT/Ni composite film. The room temperature is 20-40 deg.C, and can be adjusted within the range according to different seasons and environments.

Further, step 3), the power of ultrasonic dispersion is 200-300W, and the time of ultrasonic dispersion is 1-2 h; the heating and stirring temperature is 120-150 ℃; the mass ratio of PDMS to curing agent is 5-10: 1; the curing agent is SYLGUARD-184B; the time of vacuum de-bubbling is 30-60 min; the temperature for heating, curing and molding is 80-120 ℃. The concentration of the ethanol solution is not limited, and a commercially available ethanol solution may be purchased. The parameters (power and time) of ultrasonic dispersion in the above parameters are the original parameter range of the scheme, and the carbon nano tube can realize good dispersion in the polymer matrix under the parameter range, which is beneficial to the excellent conductivity of the composite material.

Further, the thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

The method firstly carries out surface oxidation treatment on the carbon nano tube, introduces reactive groups such as hydroxyl and the like, provides active sites, enhances the direct interface adhesion of Ni and MWCNT, weakens the Van der Waals force and the coulomb attraction force between tube bundles to a certain extent, and avoids the strong aggregation phenomenon of the carbon nano tube in the solution. It is also necessary to perform an oxidation treatment on the carbon nanotubes before electroless nickel plating, in which process the amorphous carbon and catalyst are removed and at the same time oxygen-containing functional groups such as-COOH are generated, the surface energy of the MWCNT is reduced, the activator is attached, which facilitates the further modification treatment of the MWCNT, and at the same time, promotes the more uniform dispersion of the MWCNT in the solution, avoids agglomeration, and thus allows uniform nickel plating.

In addition, the nano nickel is loaded on the MWCNT, so that the MWCNT can be prevented from agglomerating in a polymer, the interface combination is improved, and the mechanical strength and the electrical property are improved. Therefore, the surface modification of the carbon nanotubes is an effective method for improving the dispersibility of the carbon nanotubes in the polymer matrix and enhancing the interfacial bonding. The interface performance between MWCNT and PDMS in the nano composite material is improved, the rheological behavior of the nano composite material proves the good dispersion behavior of the MWCNT coated with Ni in the matrix, and the high mechanical interface performance of the final composite material is proved.

The MWCNT-Ni composite material is obtained by loading nano-nickel on the surface of the carbon nano tube by adopting a chemical plating method and is used as a filler of a PDMS polymer composite material, metal bone nodes which are firmly combined are formed on the surface of the carbon nano tube attached with metal nickel particles, a pinning inlay is formed in a polymer matrix, the carbon nano tube is prevented from caking in the PDMS matrix, the possibility that the polymer matrix slides along the surface of the carbon nano tube is avoided, and the conductivity of the composite film is improved to a certain extent under the condition that the metal nickel particles exist.

The invention has the beneficial effects that:

1. according to the invention, metal nickel is uniformly loaded on the carbon nano tube by a hydrazine reduction method, the obtained metal nickel coating is uniform and good in combination and high in purity, and the average size of nickel particles is 2 nm;

2. the raw materials used in the invention all belong to chemical raw materials which are already industrially produced, are available in the market and are easily obtained, and the synthesis process is simple, the reaction period is short, the energy consumption in the reaction process is low, and the pollution is low;

3. according to the invention, the carbon nano tube is subjected to oxidation treatment by using dilute nitric acid, so that the defect of the carbon nano tube caused by strong acid treatment is avoided, the hydrophilic reaction functional group is successfully introduced, and the conductivity of the final composite material is not influenced while the good dispersibility is ensured;

4. the invention takes the nickel-plated carbon nano tube as the filler of the polymer composite material, shows more excellent dispersibility in the PDMS matrix than the pure carbon nano tube, and improves the conductivity to a certain extent.

Drawings

FIG. 1 is a scanning electron microscope image of the carbon oxide nanotubes of example 1;

FIG. 2 is a Fourier transform infrared spectrum of the oxidized carbon nanotube of example 1;

FIG. 3 is an X-ray spectrometer spectra of the activated MWCNT and the nickel-plated MWCNT of example 1;

FIG. 4 is a scanning electron microscopy micrograph of MWCNT-Ni of example 1;

FIG. 5 is a scanning electron microscopy atlas of PDMS/MWCNT/Ni in example 1;

FIG. 6 is an X-ray diffraction pattern of MWCNT-Ni and PDMS/MWCNT/Ni obtained in example 1;

FIG. 7 is a plot of the current-voltage characteristics of the PDMS/MWCNT/Ni composite film obtained in example 1;

FIG. 8 is a scanning electron microscope atlas of the PDMS/MWCNT composite film obtained in comparative example 1;

FIG. 9 is a graph of conductivity curves of the PDMS/MWCNT/Ni composite film obtained in example 1 and the PDMS/MWCNT composite film obtained in comparative example 1;

FIG. 10 is a scanning electron microscope atlas of the Ni-P/MWCNT composite obtained in comparative example 2;

FIG. 11 is a scanning electron microscope atlas of the Ni-B/MWCNT composite obtained in comparative example 2.

Detailed Description

In order to further illustrate the technical effects of the present invention, the present invention is specifically described below by way of examples. The MWCNT in the scheme is a multi-walled carbon nano tube, and the PDMS is polydimethylsiloxane.

Example 1

1) preparing the oxidized carbon nanotube: placing the carbon nano tube in absolute ethyl alcohol to prepare dispersion liquid, carrying out pre-crushing by using an ultrasonic cell crusher, adjusting the power to be 200W, the time to be 30min, and adjusting the concentration of the carbon nano tube in the absolute ethyl alcohol to be 0.15 g/L. And (3) carrying out suction filtration and washing on the reaction product, then placing the reaction product into 5.6mol/L nitric acid solution for oxidation treatment, wherein the hydrothermal reaction condition is that the reaction temperature is 70 ℃, the reaction time is 1.5h, the concentration of the carbon nano tube in the nitric acid solution is 0.15g/L, and after the reaction is finished, repeatedly washing the reaction product to be neutral by deionized water and drying the reaction product to obtain the oxidized carbon nano tube.

In order to prove the structural characteristics of the carbon oxide nanotubes, scanning electron microscope detection is carried out, and the result is shown in fig. 1, after oxidation treatment, the tube walls of the carbon oxide nanotubes are smooth, no catalyst, impurities and amorphous carbon are attached, the tube bundles are in a uniformly dispersed state, no obvious agglomeration and entanglement exist, and the dispersibility is obviously improved.

In order to prove the component characteristics of the oxidized carbon nanotube, Fourier infrared spectrum characterization is carried out, and the result is shown in figure 2, and after oxidation treatment, the concentration of the carbon nanotube is 3000-3500 cm^-1A very obvious hydroxyl absorption peak appears at 1624.16cm^-1The existence of two absorption peaks shows that after nitric acid oxidation treatment, the oxidized carbon nanotube shows that-COOH or-COO groups are generated through reaction, and a high-activity hydrophilic group is successfully introduced into the side wall of the oxidized carbon nanotube.

2) Preparation of MWCNT-Ni composite: separately preparing SnCl₂-HCl mixed solution as sensitizing solution and PdCl₂-HCl mixed solution as activating solution, wherein SnCl₂Has a concentration of 15g/L and SnCl₂The molar ratio of HCl to HCl is 1: 3.7; PdCl₂Has a concentration of 1g/L, PdCl₂Molar ratio to HCl 1: 116. placing the carbon oxide nanotube in sensitizing solution for sensitizing reaction at 50 deg.C for 30min to obtain carbon oxide nanotube with concentration of 0.5g/L, repeatedly washing with deionized water to neutralPlacing the carbon nano tube into an activating solution, wherein the activating reaction condition is the same as the sensitization reaction condition, namely the reaction temperature is 50 ℃, the reaction time is 30min, the mass concentration of the carbon nano tube oxide in the activating solution is 0.6g/L, and after the reaction is finished, repeatedly washing the carbon nano tube oxide to be neutral by deionized water and drying the carbon nano tube oxide.

Preparing NiCl-containing material in a certain proportion relation₂·6H₂O、H₂NNH₂·H₂Taking O, aminoacetic acid, boric acid and deionized water as chemical plating solution, enabling the concentration of the activated carbon oxide nano tube in the chemical plating solution to be 0.5g/L, uniformly dispersing the activated carbon oxide nano tube in the chemical plating solution, adjusting the pH to 12 through potassium hydroxide, carrying out chemical nickel plating at 90 ℃, carrying out plating time of 15min, repeatedly washing the carbon oxide nano tube to be neutral through the deionized water after the reaction is finished, and drying the carbon oxide nano tube to obtain the MWCNT-Ni composite material.

In an electroless bath, NiCl₂·6H₂O、H₂NNH₂·H₂The mass concentrations of O, glycine and boric acid are respectively 11.87g/L, 20g/L, 22.50g/L and 30.90 g/L.

In order to prove the component characteristics of the oxidized carbon nanotube, the oxidized carbon nanotube after the activation reaction and the oxidized carbon nanotube after the nickel plating, the detection of an X-ray energy spectrometer is respectively carried out, and the result is shown in figure 3, wherein characteristic peaks of corresponding elements of Sn and Pd appear in the figure, which indicates that an Sn/Pd atomic nucleus is formed through the steps of sensitization and activation, and simultaneously, a characteristic peak of a Ni element also exists, which indicates that the Ni nanoparticles are successfully deposited on the MWCNT.

In order to verify the structural characteristics of the MWCNT-Ni composite material obtained in step 2, scanning electron microscope examination was performed, and the results are shown in fig. 4, in which the outer diameter of the carbon tube is granular nickel nanoparticles, Ni particles are uniformly deposited on the surface of the MWCNT, a continuous nickel layer is formed on the surface of the MWCNT, and the diameter of the tube is increased.

3) Preparation of PDMS/MWCNT/Ni composite film: putting MWCNT-Ni into an ethanol solution, dispersing by using an ultrasonic cell disruption instrument, performing ultrasonic dispersion for 2h at 200W to obtain a well-dispersed MWCNT-Ni suspension, then adding PDMS, heating by using a heating platform at 150 ℃ and continuously stirring, volatilizing ethanol to obtain a pasty black mixture, cooling to room temperature, adding a certain curing agent, stirring, wherein the mass ratio of PDMS to the curing agent is 10:1, the curing agent is SYLGUARD-184B, performing vacuum degassing for 1h at normal temperature, transferring the mixture without bubbles into a square mold with the size of 3cm x 0.2mm, heating, curing and stripping to obtain the PDMS/MWCNT/Ni composite film, wherein the temperature for heating, curing and molding is 100 ℃. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

In order to verify the structural characteristics of the PDMS/MWCNT/Ni composite film, scanning electron microscopy was performed to examine the structure as shown in fig. 5, in which MWCNTs were uniformly dispersed in the PDMS matrix and no agglomeration occurred, and it was observed that the MWCNTs were relatively concentrated in distribution, interconnected with each other, and formed a large number of conductive networks inside the composite film.

In order to confirm the MWCNT-Ni composite and the PDMS/MWCNT/Ni composite film, X-ray diffraction measurements were performed, respectively, and the results are shown in fig. 6.

The MWCNT-Ni composite material has a characteristic peak of nano nickel, and a diffraction peak of a carbon element of the MWCNT still exists, so that the MWCNT-Ni composite material is successfully synthesized in the step 2).

The PDMS/MWCNT/Ni composite film obtained in the step 3) has a characteristic peak coincident with the MWCNT and the PDMS, and a characteristic peak of nano nickel appears, which indicates that the PDMS/MWCNT/Ni composite material is successfully prepared.

In addition, electrical properties of PDMS/MWCNT/Ni composite films of different mass percentages were tested at room temperature, and the conductivity of the composite films was calculated from the length and cross-sectional area of the sample. The resistance of the sample was tested in a digital giga-hour meter (keithley 2400) with the aid of a data acquisition unit.

The voltammetry characteristic curves (current-voltage) of the composite film after different MWCNT-Ni composite materials are tested to fill the PDMS matrix under the room temperature condition are shown in figure 7, and it can be seen that the voltammetry curve of the PDMS/MWCNT/Ni composite film is good in linearity, linear in law and well consistent with ohm law within the range of 0-12V, and the material resistance is reduced in a number-step mode along with the increase of MWCNT-Ni conductive fillers in PDMSThat is to say, under the condition of high MWCNT content, the direct mutual bridging and linking of the carbon nanotubes are realized in the composite material, an effective conductive network is formed, and the maximum conductivity is 0.004S-cm^-1。

Example 2

1) preparing the oxidized carbon nanotube: placing the carbon nano tube in absolute ethyl alcohol to prepare dispersion liquid, carrying out pre-crushing by using an ultrasonic cell crusher, adjusting the power to 300W, the time to 45min, and the concentration of the carbon nano tube in the absolute ethyl alcohol to be 0.3 g/L. And (3) carrying out suction filtration and washing on the reaction product, then placing the reaction product into 5mol/L nitric acid solution for oxidation treatment, wherein the hydrothermal reaction condition is that the reaction temperature is 85 ℃, the reaction time is 1h, the concentration of the carbon nano tube in the nitric acid solution is 0.3g/L, and after the reaction is finished, repeatedly washing the reaction product to be neutral by deionized water and drying the reaction product to obtain the oxidized carbon nano tube.

2) Preparation of MWCNT-Ni composite: separately preparing SnCl₂-HCl mixed solution as sensitizing solution and PdCl₂-HCl mixed solution as activating solution, wherein SnCl₂Has a concentration of 20g/L and SnCl₂The molar ratio of HCl to HCl is 1: 3; PdCl₂Has a concentration of 1.5g/L and PdCl₂Molar ratio to HCl 1: 100. putting the carbon oxide nano tube into a sensitizing solution for sensitizing reaction treatment, wherein the sensitizing temperature is 40 ℃, the sensitizing time is 45min, the concentration of the carbon oxide nano tube in the sensitizing solution is 0.55g/L, repeatedly washing the carbon oxide nano tube to be neutral by deionized water after the reaction is finished, putting the carbon oxide nano tube into an activating solution, the activating reaction condition is the same as the sensitizing reaction condition, namely the reaction temperature is 40 ℃, the reaction time is 45min, the mass concentration of the carbon oxide nano tube in the activating solution is 0.65g/L, repeatedly washing the carbon oxide nano tube to be neutral by the deionized water after the reaction is finished, and drying the carbon oxide nano tube.

Preparing NiCl-containing material in a certain proportion relation₂·6H₂O、H₂NNH₂·H₂O, aminoacetic acid, boric acid and deionized water are used as chemical plating solution, the concentration of the carbon oxide nano tube after the activation reaction in the chemical plating solution is 0.65g/L, and the carbon oxide nano tube after the activation reaction is subjected to chemical platingUniformly dispersing in chemical plating solution, adjusting pH to 12.5 by potassium hydroxide, carrying out chemical nickel plating at 88 ℃, carrying out plating for 25min, repeatedly washing to neutrality by deionized water after the reaction is finished, and drying to obtain the MWCNT-Ni composite material.

In an electroless bath, NiCl₂·6H₂O、H₂NNH₂·H₂The mass concentrations of O, glycine and boric acid are respectively 13.87g/L, 23g/L, 24.50g/L and 32.90 g/L.

Preparation of PDMS/MWCNT/Ni composite film: putting MWCNT-Ni into an ethanol solution, dispersing by using a bath type ultrasonic tank, performing ultrasonic dispersion for 1h at 300W to obtain a well-dispersed MWCNT-Ni suspension, then adding PDMS, heating by using a heating platform at 130 ℃ and continuously stirring, obtaining a pasty black mixture after ethanol is volatilized, cooling to room temperature, adding a certain curing agent, stirring, wherein the mass ratio of PDMS to the curing agent is 8:1, the curing agent is SYLGUARD-184B, performing vacuum degassing for 30min at normal temperature, transferring the mixture without bubbles into a square mold with the size of 3cm to 0.2mm, heating, curing and molding at 80 ℃, and peeling to obtain the PDMS/MWCNT/Ni composite film. The composite film exhibits a conductive characteristic with an electrical conductivity of at most 0.00388S-cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Example 3

1) preparing the oxidized carbon nanotube: placing the carbon nano tube in absolute ethyl alcohol to prepare dispersion liquid, carrying out pre-crushing by using an ultrasonic cell crusher, adjusting the power to 250W and the time to 60min, wherein the concentration of the carbon nano tube in the absolute ethyl alcohol is 0.2 g/L. And (3) carrying out suction filtration and washing on the reaction product, then placing the reaction product into 4mol/L nitric acid solution for oxidation treatment, wherein the hydrothermal reaction condition is that the reaction temperature is 75 ℃, the reaction time is 2h, the concentration of the carbon nano tube in the nitric acid solution is 0.2g/L, and after the reaction is finished, repeatedly washing the reaction product to be neutral by deionized water and drying the reaction product to obtain the oxidized carbon nano tube.

2) Preparation of MWCNT-Ni composite: separately preparing SnCl₂-HCl mixed solution as sensitizing solution and PdCl₂-HCl mixed solution as activating solution, wherein SnCl₂Has a concentration of 17g/L and SnCl₂The molar ratio of HCl to HCl is 1: 5; PdCl₂Has a concentration of 1.2g/L and PdCl₂Molar ratio to HCl 1: 120. putting the carbon oxide nano tube into a sensitizing solution for sensitizing reaction treatment, wherein the sensitizing temperature is 45 ℃, the sensitizing time is 35min, the concentration of the carbon oxide nano tube in the sensitizing solution is 0.65g/L, repeatedly washing the carbon oxide nano tube to be neutral by deionized water after the reaction is finished, putting the carbon oxide nano tube into an activating solution, the activating reaction condition is the same as the sensitizing reaction condition, namely the reaction temperature is 45 ℃, the reaction time is 35min, the mass concentration of the carbon oxide nano tube in the activating solution is 0.45g/L, repeatedly washing the carbon oxide nano tube to be neutral by the deionized water after the reaction is finished, and drying the carbon oxide nano tube.

Preparing NiCl-containing material in a certain proportion relation₂·6H₂O、H₂NNH₂·H₂Taking O, aminoacetic acid, boric acid and deionized water as chemical plating solution, wherein the concentration of the activated carbon oxide nano tube in the chemical plating solution is 0.45g/L, uniformly dispersing the activated carbon oxide nano tube in the chemical plating solution, adjusting the pH to 10.5 by potassium hydroxide, carrying out chemical nickel plating at 85 ℃, carrying out plating time of 30min, repeatedly washing the carbon oxide nano tube to be neutral by the deionized water after the reaction is finished, and drying the carbon oxide nano tube to obtain the MWCNT-Ni composite material.

In an electroless bath, NiCl₂·6H₂O、H₂NNH₂·H₂The mass concentrations of O, glycine and boric acid are respectively 12.87g/L, 22g/L, 23.50g/L and 31.90 g/L.

3) Preparation of PDMS/MWCNT/Ni composite film: putting MWCNT-Ni into an ethanol solution, dispersing by using a bath type ultrasonic tank, performing ultrasonic dispersion for 1.5h at 250W to obtain a well-dispersed MWCNT-Ni suspension, then adding PDMS (polydimethylsiloxane), heating by using a heating platform at 120 ℃ and continuously stirring, obtaining a scorched black mixture after volatilizing ethanol, cooling to room temperature, adding a certain curing agent for stirring, wherein the mass ratio of the PDMS to the curing agent is 5:1, the curing agent is SYLGUARD-184B, and then performing ultrasonic dispersion at normal temperatureVacuum degassing for 45min, transferring the mixture without bubbles into a square mold with the size of 3cm by 0.2mm, heating, curing and molding at 120 ℃, and stripping to obtain the PDMS/MWCNT/Ni composite film. The composite film exhibits a conductive characteristic with an electrical conductivity of at most 0.00376S-cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Comparative example 1

To demonstrate the effect of nickel plating on the surface of carbon nanotubes on the conductivity of the composite film, a PDMS/MWCNT/Ni composite film was prepared using MWCNTs as the conductive filler, so comparative example 1 was provided.

The PDMS/MWCNT/Ni composite material was prepared using MWCNT as a conductive additive, and the steps not specifically described were the same as the preparation method of example 1, except that: the surface oxidation treatment and nickel particle deposition operation were not performed on the carbon nanotubes, and the MWCNT was directly used to prepare the composite film in step 3, and the rest of the steps were the same as in example 1, and the obtained material was PDMS/MWCNT.

The scanning electron microscope examination of the obtained PDMS/MWCNT thin film material shows that the result is shown in fig. 8, and the picture shows that when the original MWCNT is directly used as the conductive filler to prepare the PDMS/MWCNT composite film, the MWCNT exhibits a severe strong aggregation phenomenon in the PDMS matrix, and cannot be dispersed well.

And electrical property characterization is carried out, and the result is shown in fig. 9, and the result shows that the electrical property of the PDMS/MWCNT/Ni composite film is improved by several orders of magnitude compared with that of the PDMS/MWCNT, and the electrical conductivity is effectively improved, which indicates that the electrical conductivity of the composite material can be improved to a certain extent by carrying out nickel plating treatment on the carbon nanotube. The conductivity is at most 0.00276S cm^-1。

Comparative example 2

To prove that the hydrazine reduction method for preparing the nickel-plated carbon nanotube can obtain a good and uniform plating layer, other reducing agents, namely sodium hypophosphite and potassium borohydride, are adopted as reducing agents for nickel plating reaction, so that a comparative example 2 is provided, and steps which are not specifically described are the same as the preparation method of the example 1, except that: in the nickel plating process, other sodium hypophosphite and potassium borohydride are used as reducing agents to reduce nickel ions, which are respectively marked as Ni-P/MWCNT and Ni-B/MWCNT.

The obtained Ni-P/MWCNT and Ni-B/MWCNT composite materials are respectively subjected to scanning electron microscope detection, and the results are shown in fig. 10 and fig. 11. The conductivity is at most 0.00269S cm^-1。

Comparative example 3

In the comparative example, in the step 1), the adjusting power of the ultrasonic crushing treatment is 500W, and the time of the ultrasonic crushing treatment is 20 min; the rest of the steps are consistent with example 1; the maximum conductivity of the PDMS/MWCNT/Ni composite film is 0.00277S cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Comparative example 4

In the comparative example, in the step 2), the sensitizing solution in the sensitization reaction was SnCl₂-HCl mixed solution, wherein SnCl₂Has a concentration of 10g/L and SnCl₂The molar ratio of HCl to HCl is 1: 1; the temperature of the sensitization reaction is 30 ℃, the time of the sensitization reaction is 20min, and the concentration of the oxidized carbon nano tube in the sensitization liquid is 0.3 g/L; the activating solution in the activation reaction is PdCl₂HCl solution, in which PdCl₂Has a concentration of 0.5g/L and PdCl₂Molar ratio to HCl 1: 50, the temperature of the activation reaction is 30 ℃, the time of the activation reaction is 20min, and the concentration of the oxidized carbon nano tube in the activation solution is 0.3 g/L; the rest of the steps are consistent with example 1; the maximum conductivity of the PDMS/MWCNT/Ni composite film is 0.00268S-cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Comparative example 5

In this comparative example, in step 2), NiCl was added₂·6H₂O concentration of 10g/L, H₂NNH₂·H₂The concentration of O is 15g/L, the concentration of glycine is 20g/L, and the concentration of boric acid is 25 g/L; the rest of the steps are consistent with example 1; the maximum conductivity of the PDMS/MWCNT/Ni composite film is 0.00257S cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Comparative example 6

Comparative exampleIn the step 2), the chemical plating solution is adjusted to pH 8 by using potassium hydroxide; the temperature of the chemical nickel plating is 70 ℃, and the time of the chemical nickel plating is 10 min; the rest of the steps are consistent with example 1; the maximum conductivity of the PDMS/MWCNT/Ni composite film is 0.00259S cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Comparative example 7

In the comparative example, in the step 3), the power of ultrasonic dispersion is 100W, and the time of ultrasonic dispersion is 3 h; the rest of the steps are consistent with example 1; the maximum conductivity of the PDMS/MWCNT/Ni composite film is 0.00248S cm^-1. The thickness of the prepared PDMS/MWCNT/Ni composite film is 200 microns.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the technical solutions of the present invention are described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A preparation method of nickel-plated carbon nanotube enhanced PDMS composite film conductive performance is characterized by comprising the following steps:

1) pretreating the carbon nano tube to prepare an oxidized carbon nano tube;

2. The method of claim 1, wherein the step 1) comprises the steps of: placing the carbon nano tube in absolute ethyl alcohol to prepare dispersion, crushing the carbon nano tube by using an ultrasonic cell crusher, then carrying out suction filtration and washing, placing the crushed carbon nano tube in a nitric acid solution for oxidation treatment, finally washing the carbon nano tube to be neutral by using deionized water, and drying the carbon nano tube to obtain the nano tube.

3. The preparation method as claimed in claim 2, wherein in the step 1), the adjusting power of the ultrasonication treatment is 200- "300W", and the time of the ultrasonication treatment is 30-60 min; the concentration of nitric acid in the nitric acid solution is 4-5.6mol/L, the concentration of the carbon nano tube in the dispersion liquid is 0.15-0.3g/L, the reaction temperature of the oxidation treatment is 70-85 ℃, the reaction time of the oxidation treatment is 1-2h, and the concentration of the carbon nano tube in the nitric acid solution is 0.15-0.3 g/L.

4. The method according to claim 1, wherein the MWCNT-Ni composite material is prepared by the method of step 2): and (2) carrying out sensitization reaction and activation reaction on the carbon oxide nano tube in sequence, uniformly dispersing the carbon oxide nano tube subjected to the activation reaction in a chemical plating solution, carrying out chemical nickel plating, washing the carbon oxide nano tube to be neutral by deionized water, and drying the carbon oxide nano tube to obtain the carbon oxide nano tube.

5. The method according to claim 4, wherein the sensitizing solution in the sensitization reaction in step 2) is SnCl₂-HCl mixed solution, wherein SnCl₂The concentration of (A) is 15-20g/L, SnCl₂The molar ratio of HCl to HCl is 1: 3-5; the temperature of the sensitization reaction is 40-50 ℃, the time of the sensitization reaction is 30-45min, and the concentration of the oxidized carbon nano tube in the sensitization liquid is 0.45-0.65 g/L; the activating solution in the activation reaction is PdCl₂HCl solution, in which PdCl₂The concentration of (A) is 1-1.5g/L, PdCl₂The mol ratio of the carbon nano tube to HCl is 1:100-120, the temperature of the activation reaction is 40-50 ℃, the time of the activation reaction is 30-45min, and the concentration of the carbon nano tube oxide in the activation solution is 0.45-0.65 g/L; the carbon oxide nanotubes after the sensitization reaction and the activation reaction are repeatedly washed to be neutral by deionized water and dried.

6. The method of claim 5, wherein the electroless plating solution of step 2) comprises NiCl₂·6H₂O、H₂NNH₂·H₂O, aminoacetic acid, boric acid and deionized water,wherein NiCl₂·6H₂O concentration of 11.87-13.87g/L, H₂NNH₂·H₂The concentration of O is 20-23g/L, the concentration of glycine is 22.5-24.5g/L, and the concentration of boric acid is 30.9-32.9 g/L; the concentration of the carbon oxide nano tube after the activation reaction in the chemical plating solution is 0.45-0.65 g/L.

7. The method according to claim 6, wherein in the step 2), the electroless plating solution is adjusted to pH 10.5 to 12.5 using potassium hydroxide; the temperature of the chemical nickel plating is 85-90 ℃, and the time of the chemical nickel plating is 15-30 min.

8. The method according to claim 1, wherein the PDMS/MWCNT/Ni composite film in step 3) is prepared by: putting the MWCNT-Ni composite material into an ethanol solution, performing ultrasonic dispersion by using an ultrasonic cell disruption instrument to obtain MWCNT-Ni suspension, then adding PDMS, heating and stirring, volatilizing ethanol to obtain a coke-paste black mixture, then cooling to room temperature, adding a curing agent, stirring, performing vacuum defoaming at normal temperature, and finally heating, curing and molding to obtain the MWCNT-Ni composite material.

9. The preparation method according to claim 8, wherein the power of the ultrasonic dispersion in step 3) is 200-300W, and the time of the ultrasonic dispersion is 1-2 h; the heating and stirring temperature is 120-150 ℃; the mass ratio of PDMS to curing agent is 5-10: 1; the curing agent is SYLGUARD-184B; the time of vacuum de-bubbling is 30-60 min; the temperature for heating, curing and molding is 80-120 ℃.

10. A PDMS/MWCNT/Ni composite film manufactured by the manufacturing method according to any one of claims 1 to 9.