CN105887054A - High-conductivity biomass and nanometal flexible composite film and preparation method thereof - Google Patents

Abstract

The invention discloses a high-conductivity biomass/nano-metal flexible composite film and a preparation method thereof, comprising the following steps: (1) immersing the biomass substrate in a dopamine buffer solution, stirring continuously, and washing the obtained film with deionized water rinse once to obtain a composite film whose surface is covered with polydopamine; (2) immerse the above composite film in an aqueous solution of (NH ₄ ) ₂ PdCl ₄ and stir to fix the catalyst on the surface of the substrate; (3) apply step (2) The obtained composite film is rinsed with deionized water several times, then immersed in the plating solution of copper or silver or gold or nickel at room temperature for at least 5 minutes, the obtained film is washed with deionized water, and finally dried to obtain a raw material with a metallic luster on the surface. Substance/nano-metal/nano-metal composite film. The invention has the advantages of simple operation, short time consumption and low cost; the obtained biomass/nano metal composite thin film has high conductivity or high reflectivity.

Description

A kind of highly conductive biomass/nano-metal flexible composite film and preparation method thereof

technical field

The invention belongs to the fields of chemical deposition metal and photoelectrochemistry, and in particular relates to a biomass/nano-metal composite thin film and a preparation method thereof.

Background technique

The rapid development of portable and wearable electronic devices has led to a rapid increase in the demand for highly conductive and flexible materials. Polymer-based conductive materials are widely used here because of their excellent flexibility, low cost, and multifunctionality. Conductive flexible films or fabrics can be prepared from conductive polymers or flexible polymers, such as PET, paper, rubber, etc. Due to the depletion of ore resources and the aggravation of environmental problems, biopolymers have gradually become an important source of alternative petroleum-based materials. Compared with petroleum-based materials, biopolymers have their unique advantages, such as biodegradability, biocompatibility, environmental friendliness, low cost, renewable, etc. Among them, cellulose, as the most abundant resource in nature, has been widely used in packaging and other fields, especially because of its strong mechanical strength and inherent flexibility, cellulose has great potential in the fields of flexible conductivity and energy storage.

There have been a lot of researches on the composite of conductive materials such as graphene and carbon nanotubes with cellulose to form conductive flexible films. However, the preparation of these conductive products often requires complicated operation processes and the addition of expensive fillers often increases the application cost and limits the application cost. Its wide application. From the perspective of conductivity and cost, metal is still the best choice for making conductive materials.

Current methods of metal spraying mainly include physical vapor deposition, chemical vapor deposition, electrochemical metal deposition, and chemical deposition of metal. Among them, electroless metal deposition is a method that can produce high-quality metal structures on flexible and stretchable substrates. This method does not require high-temperature treatment, expensive equipment and conductive substrates, so the cost is low. The chemical deposition process includes two steps: (1) the fixation of the anchor layer on the surface of the substrate to the metal catalyst; (2) the growth of the metal in the plating solution. Among them, the anchoring layer is very important, because it not only determines the immobilization efficiency of the catalyst, thereby affecting the subsequent redox reaction, but also the anchoring layer should have a good adhesion effect on the plated metal. Therefore, it is necessary to graft polymer molecular brushes on the surface of the substrate as an anchoring layer, but the grafting method is complicated, and the equipment required is expensive and the cost is high.

Contents of the invention

The invention provides a method for preparing a polydopamine-assisted electroless deposition high-conductivity biomass/nano-metal flexible composite film, which adopts a simple impregnation method, uses biomass materials as a substrate, and polydopamine as an anchoring agent to effectively fix metal catalysts , so that redox reactions occur on the surface of biomass materials to deposit metals. The existing surface metallization technology solves the problems of cumbersome operation, long time consumption, poor electrical conductivity, and easy fall off of surface metal, and is applicable to materials of various shapes made of various biomass raw materials.

The present invention is specifically realized through the following technical solutions:

A preparation method of polydopamine-assisted electroless deposition of highly conductive biomass/nano-metal flexible composite film, comprising the steps of:

(1) Immersing the biomass substrate in a dopamine buffer solution, and continuously stirring at a speed of 100-500rpm for 0.5-24h, washing the obtained film with deionized water multiple times to obtain a composite film covered with polydopamine;

(2) immersing the above-mentioned composite film in an aqueous solution of (NH ₄ ) ₂ PdCl ₄ , stirring at 100-500 rpm for 0.5-4 hours, so that the catalyst is fixed on the surface of the substrate;

(3) After washing the composite film obtained in step (2) with deionized water several times, immerse it in the plating solution of copper or silver or gold or nickel at room temperature for at least 5min, and the obtained film is washed with deionized water, and finally Dry to obtain a biomass/nano-metal/nano-metal composite film with metallic luster on the surface.

The dopamine buffer solution in the step (1) is Tris·HCl buffer solution of dopamine, the concentration is 0.5-5 mg/ml, and the pH of the Tris·HCl buffer solution is 6.0-10.0.

The concentration of the (NH ₄ ) ₂ PdCl ₄ aqueous solution in step (2) is 0.1 mg/ml-1 mg/ml.

The soaking time in step (3) is 10-60 minutes.

The drying described in step (3) is air drying or vacuum drying, and the temperature of vacuum drying is 25-60°C.

The biomass substrate comprises two-dimensional or three-dimensional materials made from biomass raw materials.

The biomass substrate is cellulose paper, cellulose, chitosan, hemicellulose or modified transparent film, aerogel, hydrogel, fiber fabric.

The copper plating solution is a mixed solution of NaOH, CuSO ₄ 5H ₂ O, potassium sodium tartrate and reducing agent formaldehyde; the silver plating solution is a mixture of [Ag(NH ₃ ) ₂ ]NO ₃ and potassium sodium tartrate The nickel plating solution is a mixed solution of NiSO ₄ 5H ₂ O, sodium citrate, lactic acid and dimethylamine borane; the gold plating solution is HAuCl ₄ , NaOH, NH ₂ OH·HCl, Na ₂ HPO ₄ , a mixture of NaS ₂ O ₃ ·5H ₂ O and Na ₂ SO ₃ .

The plating solution of described copper is made up of 12g/L NaOH, 13g/L CuSO 5H ₂ O, 29g/L potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde _; The plating solution of described silver is made up of 1g/L [Ag (NH ₃ ) ₂ ]NO ₃ and 5g/L potassium sodium tartrate; the nickel plating solution consists of 40g/L NiSO ₄ ·5H ₂ O, 20g/L sodium citrate, 10g/L lactic acid and 1g/L Dimethylamine borane is mixed at a volume ratio of 4:1, and the pH is adjusted to 8 with ammonia water; the gold plating solution is 3.3g/L HAuCl ₄ , 0.4g/L NaOH, 6.95g/L NH ₂ OH· HCl, 11g/L Na ₂ HPO ₄ , 16g/L NaS ₂ O ₃ ·5H ₂ O and 40g/L Na ₂ SO ₃ are mixed.

In the biomass/nano-metal composite thin film prepared by the above method, the formed metal can be firmly adhered to the biomass substrate. The nitrogen-containing group of polydopamine can firmly combine with catalyst metal ions, and at the same time play a role in stabilizing the deposited metal.

The invention adopts a simple dipping method, uses polydopamine as an anchor layer, and chemically deposits metal on the surface of a cellulose substrate (or other biomass raw materials as a substrate). The prepared biomass/nano-metal composite film has good electrical conductivity, and the deposited metal can be firmly attached to the substrate surface. The preparation process is simple and easy to operate and can be completed at room temperature. The prepared biomass/nano-metal composite films have great application potential in energy storage, electronic equipment and other fields.

Compared with the existing polymer surface metallization process, the present invention has the following advantages:

(1) The present invention is simple to operate, time-consuming is shorter, and cost is lower;

(2) There is strong adhesion between the metal on the surface of the composite film prepared by the present invention and the substrate, the metal is not easy to fall off, and the formed metal layer is uniform and dense.

(3) The biomass raw materials and dopamine (belonging to biomass) used are environmentally friendly, biodegradable and biocompatible materials, and the resulting biomass/nano-metal composite film has high conductivity or high reflectivity, It can be used in metallurgy, optoelectronic devices, wearable electronic devices, chemical industry, biosensing, implantable electronic devices, energy storage, military technology and other important fields, which greatly broadens the application range of biomass materials.

Description of drawings

Fig. 1 is the mass change curve of filter paper and cotton cloth with copper plating time in Examples 1-4 of the present invention.

Fig. 2 is the variation of sheet resistance of filter paper and cotton cloth with copper plating time in Examples 1-4 of the present invention.

Fig. 3 is a SEM image (a) and an energy spectrum image (b) of the filter paper/nano-copper composite film in Example 2 of the present invention.

Fig. 4 is a SEM image (a) and an energy spectrum image (b) of the cotton cloth/nano-copper conductive fabric in Example 2 of the present invention.

5 is an SEM image of the chitosan film/nano-copper conductive composite film in Example 5 of the present invention.

Fig. 6 is a test chart of resistance stability of the filter paper/nano-copper composite film in Example 3 of the present invention.

detailed description

The present invention will be further described below in conjunction with specific examples, but not limited thereto.

Example 1

Cut filter paper or cotton cloth of a certain size and soak in 1 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stir at 300 rpm for 6 hours. The obtained filter paper or cotton cloth covered with polydopamine was rinsed with deionized water several times, soaked in 0.1 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 1 h. Wash the obtained filter paper or cotton cloth with metal catalyst adsorbed thereon several times with deionized water, then immerse in the copper plating solution for 5 minutes, the plating solution consists of 12g/L NaOH, 13g/L CuSO ₄ 5H ₂ O, 29g/L Potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde. After the reaction is completed, the metal-coated filter paper or cotton cloth is rinsed with deionized water and dried in a vacuum oven at 50°C. Weigh the quality of the filter paper and cotton cloth before and after the reaction, and test their resistance with a four-probe square resistance tester.

Example 2

Cut filter paper or cotton cloth of a certain size and soak in 1 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stir at 300 rpm for 6 hours. The obtained filter paper or cotton cloth covered with polydopamine was rinsed with deionized water several times, soaked in 0.1 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 1 h. After washing the filter paper or cotton cloth with the metal catalyst adsorbed thereon several times with deionized water, immerse it in the copper plating solution for 10 minutes. The plating solution consists of 12g/L NaOH, 13g/L CuSO ₄ 5H ₂ O, 29g/L Potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde. After the reaction is completed, the metal-coated filter paper or cotton cloth is rinsed with deionized water and dried in a vacuum oven at 50°C. Weigh the quality of the filter paper and cotton cloth before and after the reaction, and test their resistance with a four-probe square resistance tester.

Example 3

Cut filter paper or cotton cloth of a certain size and soak in 1 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stir at 300 rpm for 6 hours. The obtained filter paper or cotton cloth covered with polydopamine was rinsed with deionized water several times, soaked in 0.1 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 1 h. Wash the obtained filter paper or cotton cloth with metal catalyst adsorbed thereon with deionized water several times, then soak it in the copper plating solution for 30min, the plating solution consists of 12g/L NaOH, 13g/L CuSO ₄ 5H ₂ O, 29g/L Potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde. After the reaction is completed, the metal-coated filter paper or cotton cloth is rinsed with deionized water and dried in a vacuum oven at 50°C. Weigh the quality of the filter paper and cotton cloth before and after the reaction, and test their resistance with a four-probe square resistance tester.

Example 4

Cut filter paper or cotton cloth of a certain size and soak in 1 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stir at 300 rpm for 6 hours. The obtained filter paper or cotton cloth covered with polydopamine was rinsed with deionized water several times, soaked in 0.1 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 1 h. After washing the obtained filter paper or cotton cloth with metal catalyst adsorbed thereon several times with deionized water, immerse in the copper plating solution for 60min, the plating solution consists of 12g/L NaOH, 13g/L CuSO ₄ 5H ₂ O, 29g/L Potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde. After the reaction is completed, the metal-coated filter paper or cotton cloth is rinsed with deionized water and dried in a vacuum oven at 50°C. Weigh the quality of the filter paper and cotton cloth before and after the reaction, and test their resistance with a four-probe square resistance tester.

Example 5

A chitosan film cut to a certain size was soaked in 2 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stirred at 300 rpm for 12 hours. The resulting chitosan film covered with polydopamine was rinsed with deionized water several times, soaked in 0.5 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 3 hours. The resulting chitosan film adsorbed with a metal catalyst was washed with deionized water several times, then immersed in a copper plating solution for 5 minutes, and the plating solution consisted of 12g/L NaOH, 13g/L CuSO ₄ 5H ₂ O, 29g/L L potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde. After the reaction was completed, the metal-plated chitosan film was rinsed with deionized water and dried in a vacuum oven at 50°C. Test its resistance with a four-probe square resistance tester.

Example 6

A chitosan film cut to a certain size was soaked in 2 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stirred at 300 rpm for 12 hours. The resulting chitosan film covered with polydopamine was rinsed with deionized water several times, soaked in 0.5 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 3 hours. The resulting chitosan film adsorbed with the metal catalyst was washed with deionized water several times, and then immersed in a nickel plating solution for 10 minutes. After the reaction was completed, the metal-plated chitosan film was rinsed with deionized water, dried at room temperature, and tested for its resistance with a four-probe square resistance tester.

Example 7

A chitosan film cut to a certain size was soaked in 2 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stirred at 300 rpm for 12 hours. The resulting chitosan film covered with polydopamine was rinsed with deionized water several times, soaked in 0.5 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 3 hours. The resulting chitosan film adsorbed with the metal catalyst was washed with deionized water several times, then immersed in the copper plating solution for a few seconds, and then immersed in the silver plating solution for 30 minutes. After the reaction was completed, the metal-plated chitosan film was rinsed with deionized water, dried at room temperature, and tested for its resistance with a four-probe square resistance tester.

Example 8

A chitosan film cut to a certain size was soaked in 2 mg/ml dopamine/Tris·HCl buffer solution (pH=8.5), and stirred at 300 rpm for 12 hours. The resulting chitosan film covered with polydopamine was rinsed with deionized water several times, soaked in 0.5 mg/ml (NH ₄ ) ₂ PdCl ₄ aqueous solution, and stirred at 300 rpm for 3 hours. The resulting chitosan film adsorbed with the metal catalyst was washed with deionized water several times, then immersed in the copper plating solution for a few seconds, and then immersed in the gold plating solution for 30 minutes. After the reaction was completed, the metal-plated chitosan film was rinsed with deionized water, dried at room temperature, and tested for its resistance with a four-probe square resistance tester.

Figure 1 is the mass change curve of filter paper and cotton cloth with copper plating time. It can be seen from the figure that with the prolongation of the time of the biomass substrate in the plating solution, the metal content plated on the surface of the substrate is getting higher and higher. It shows that the metal catalyst can be successfully attached to the surface of the substrate, so that the metal can be successfully plated.

Figure 2 The sheet resistance change of filter paper and cotton cloth with copper plating time. It can be seen from the figure that whether it is filter paper or cotton cloth, with the prolongation of its time in the metal plating solution, its square resistance gradually decreases, and the variance of the surface square resistance gradually decreases, indicating that the coating is more and more uniform. Combined with Figure 1, it shows that as time increases, the metal coating gradually becomes thicker and uniform, resulting in a gradual decrease in resistance. In particular, the filter paper can reach 0.13Ω/□ when immersed in the plating solution for 10 minutes, which shows that it has good conductivity.

Figure 3 SEM image and energy spectrum of the filter paper/nano-copper composite film. It can be seen from the figure that the inner fibers of the filter paper have been coated with metal nanoparticles, indicating that the filter paper is fully impregnated when impregnated with dopamine and the subsequent metal catalyst, so that the subsequent surface metallization is also sufficient, which is its electrical conductivity. superior reason. And the coating is uniform, which is the reason why the variance of the surface resistance of the filter paper is small. It can be seen from the energy spectrum that a layer of copper particles is plated on the surface of the filter paper.

Figure 4 SEM image and energy spectrum image of cotton cloth/nano-copper conductive fabric. It can be seen from the figure that the inner fibers of the filter paper have been coated with metal nanoparticles, indicating that the filter paper is fully impregnated when impregnated with dopamine and the subsequent metal catalyst, so that the subsequent surface metallization is also sufficient, which is its electrical conductivity. superior reason. From the comparison of the SEM images of cotton cloth and filter paper, it can be seen that the cotton cloth has more pores and is not as dense as the filter paper, so it takes longer for the plating solution to enter the interior of the cotton cloth. So, cotton cloth takes longer than filter paper to achieve the same conductivity.

Fig. 5 SEM image of chitosan film/nano-copper conductive composite film. It can be seen from the figure that the surface of the chitosan film has been evenly coated with a layer of copper nanoparticles, and the copper nanoparticles are uniform in size and densely arranged. Compared with filter paper and cotton cloth, the surface of chitosan film is smoother, so the formed coating is also smoother.

Fig. 6 Resistance stability test chart of filter paper/nano-copper composite film. It can be seen from the figure that the resistance of the conductive filter paper hardly changes when the degree of bending is different, indicating that the conductive layer is firmly bonded to the filter paper, and the conductive layer will not fall off under bending, which will not affect its resistance change. However, in the case of multiple folds, due to the limited folding endurance of the paper, after more than 50 folds, the paper has been broken, resulting in discontinuity of the conductive layer and a greatly increased resistance.

The resistance value of the conductive composite film in table 1 embodiment 5-8

It can be seen from Table 1 that the resistance of the film deposited on copper is the smallest, which may be related to the faster deposition rate of copper. Therefore, it takes longer time for thin films to achieve lower resistance when depositing nickel, gold, and silver.

Claims (10)

1. A preparation method of highly conductive biomass/nano-metal flexible composite film, characterized in that, comprising the steps: (1) Immersing the biomass substrate in a dopamine buffer solution, and continuously stirring at a speed of 100-500rpm for 0.5-24h, washing the obtained film with deionized water multiple times to obtain a composite film covered with polydopamine; (2) immersing the above-mentioned composite film in an aqueous solution of (NH ₄ ) ₂ PdCl ₄ , stirring at 100-500 rpm for 0.5-4 hours, so that the catalyst is fixed on the surface of the substrate; (3) After washing the composite film obtained in step (2) with deionized water several times, immerse it in the plating solution of copper or silver or gold or nickel at room temperature for at least 5min, and the obtained film is washed with deionized water, and finally Dry to obtain a biomass/nano-metal/nano-metal composite film with metallic luster on the surface. 2. preparation method according to claim 1, is characterized in that, described in step (1) the Tris HCl damping fluid of dopamine damping fluid is the Tris HCl damping fluid of dopamine, and concentration is 0.5-5mg/ml, the pH of Tris HCl damping fluid =6.0-10.0. 3. The preparation method according to claim 1 or 2, characterized in that the concentration of the (NH ₄ ) ₂ PdCl ₄ aqueous solution in step (2) is 0.1 mg/ml-1 mg/ml. 4. The preparation method according to claim 1 or 2, characterized in that the soaking time in step (3) is 10-60 min. 5. The preparation method according to claim 1 or 2, characterized in that, the drying in step (3) is air drying or vacuum drying, and the temperature of vacuum drying is 25-60°C. 6. The preparation method according to claim 1 or 2, characterized in that, the biomass substrate comprises a two-dimensional or three-dimensional material made from biomass raw materials. 7. preparation method according to claim 6, is characterized in that, described biomass substrate is cellulose paper, cellulose, chitosan, hemicellulose or its modified transparent film, aerogel, hydrogel Glue, fiber fabric. 8. according to the described preparation method of claim 1 or 2, it is characterized in that, the plating solution of described copper is the mixed solution of NaOH, CuSO ₄ 5H ₂ O, potassium sodium tartrate and reducing agent formaldehyde; The solution is a mixed solution of [Ag(NH ₃ ) ₂ ]NO ₃ and potassium sodium tartrate, and the nickel plating solution is a mixed solution of NiSO ₄ 5H ₂ O, sodium citrate, lactic acid and dimethylamine borane; The gold plating solution mentioned above is a mixed solution of HAuCl ₄ , NaOH, NH ₂ OH·HCl, Na ₂ HPO ₄ , NaS ₂ O ₃ ·5H ₂ O and Na ₂ SO ₃ . 9. preparation method according to claim 8 is characterized in that, the plating solution of described copper is made of 12g/ _{LNaOH, 13g/L CuSO 5H 2 O} , 29g/L potassium sodium tartrate and reducing agent 9.5ml/L formaldehyde; the silver plating solution consists of 1g/L [Ag(NH ₃ ) ₂ ]NO ₃ and 5g/L potassium sodium tartrate; the nickel plating solution consists of 40g/L NiSO ₄ 5H ₂ O, 20g /L sodium citrate, 10g/L lactic acid and 1g/L dimethylamine borane are mixed at a volume ratio of 4:1, and the pH is adjusted to 8 with ammonia water; the gold plating solution is 3.3g/LHAuCl ₄ , 0.4g/L NaOH, 6.95g/L NH ₂ OH·HCl, 11g/L Na ₂ HPO ₄ , 16g/L NaS ₂ O ₃ ·5H ₂ O and 40g/L Na ₂ SO ₃ are mixed. 10. The biomass/nano-metal composite film prepared by the method according to any one of claims 1 to 9.