Flexible silver reinforced carbon fiber composite material as well as preparation method and application thereof
Through dopamine activation treatment and electroless plating, the impedance mismatch caused by the high conductivity of carbon fibers is solved, and efficient electromagnetic shielding performance and material flexibility and stability are achieved. It is suitable for the new generation of wearable electronic products.
Patent Information
- Application Number
- CN202311186482.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-14
- Publication Date
- 2024-12-20
AI Technical Summary
In the prior art, the high conductivity of carbon fibers leads to impedance mismatch, complex pretreatment processes and expensive reagents are required, and additional reducing agents are required during the electroless silver plating process, which affects the weight gain, flexibility and EMI shielding of the material. characteristic.
Dopamine activation treatment is used to adhere the polydopamine film on the carbon fiber surface, promoting silver loading, and without additional reducing agents during the electroless plating process, silver nanoparticles are directly formed through the reduction of dopamine, simplifying the process and improving silver loading efficiency.
It realizes efficient electromagnetic shielding performance, with silver load reaching 50.12dB, excellent SE value of 1044.82dB cm2/g, and maintains the flexibility and stability of the material. After 100 bending times, the EMI SE retention rate reaches 92%, which is suitable for for wearable sensors and flexible electronic devices.
Smart Images
Figure CN119162821A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electromagnetic interference shielding materials, and in particular to a flexible silver-reinforced carbon fiber composite material, a preparation method thereof, and application thereof in electromagnetic interference shielding. Background Art
[0002] The booming development of 5G communications and electronic products has brought great convenience and entertainment to human beings. At the same time, the electromagnetic radiation generated also poses a serious threat to human health. Therefore, it is urgent to explore efficient and flexible electromagnetic interference (EMI) shielding materials to solve the problem of electromagnetic pollution.
[0003] Carbon fibers (CFs) have attracted much attention due to their excellent electrical properties, low density, and good mechanical properties. However, the high electrical conductivity of carbon fibers (CFs) can lead to impedance mismatch, resulting in strong reflection of incident electromagnetic waves and secondary pollution. Therefore, in order to improve the electromagnetic shielding performance, it is necessary to modify the surface of carbon fibers to solve the problem of impedance mismatch caused by the high electrical conductivity of carbon fibers.
[0004] In the prior art, in order to improve electromagnetic shielding performance, silver-reinforced composite materials are usually prepared by chemically plating silver on carbon fibers. The introduction of silver particles can promote an efficient conductive three-dimensional network and provide more interface reflection and reabsorption for electromagnetic waves.
[0005] Since the surface of carbon fiber has no catalytic activity, it is generally necessary to perform sensitization, activation, and reduction treatments before implementing the chemical silver plating process. The pretreatment process before implementing chemical silver plating is often related to the success or failure of the chemical silver plating process. For example, prior art 1 (Guan Hua, Pan Gongpei, Hou Wei, et al. Optimization of chemical silver plating process for carbon fiber cloth [J]. Electroplating and Finishing, 2008 (27): 20-23.) discloses a chemical silver plating process for carbon fiber cloth, which specifically includes: 1) pre-treating the surface of the carbon fiber cloth before chemical silver plating; the pre-treatment process mainly includes five steps: degumming, degreasing, roughening, sensitization, and activation. 2) The pre-treated carbon fiber cloth is then transferred to the chemical silver plating solution for plating: 10.5g / L silver nitrate, 100mL / L ammonia water, 10g / L sodium hydroxide, 22.5g / L glucose, 50mL / L ethanol, plating temperature 20°C, plating time 10min.
[0006] In the pretreatment process of prior art 1, reagents such as stannous chloride and palladium chloride are required, but these reagents are expensive, the method is relatively complicated, and heavy metal ion waste liquid is generated. In addition, in the plating process of prior art 1, the additional reducing agent glucose needs to be added. The amount of glucose added will not only affect the weight gain rate of the silver-plated carbon fiber cloth, but also affect its softness and EMI shielding properties. Therefore, in order to avoid the influence of the additional reducing agent on the weight gain rate, softness and EMI shielding properties of the carbon fiber cloth, it is necessary to provide a silver-reinforced carbon fiber composite material with lightweight, flexible and efficient EMI shielding properties to meet the application needs of the new generation of wearable electronic products. Summary of the invention
[0007] In order to solve the problems of high cost, heavy metal ion waste liquid generated in the prior art and the need to add additional reducing agent during the plating process, the purpose of the present invention is to provide a flexible silver reinforced carbon fiber composite material and a preparation method and use in electromagnetic interference shielding.
[0008] The present invention utilizes activation treatment of dopamine to make a layer of polydopamine film adhere to the surface of the carbon fiber, which plays an interface bonding role and promotes the loading of silver; and dopamine also has a certain reducing effect, so there is no need to add additional reducing agent during the chemical plating process, and it will not affect the weight gain rate, softness and EMI shielding characteristics of the carbon fiber composite material.
[0009] To achieve the above objectives, the technical solution of the present invention is as follows.
[0010] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0011] S1. placing the carbon fiber material in a Tris buffer solution, then adding dopamine hydrochloride under stirring, continuing to stir the reaction, filtering, and obtaining a carbon fiber material activated with dopamine;
[0012] S2. Immersing the carbon fiber material activated by dopamine in a silver ammonia solution for chemical plating, filtering, and obtaining a flexible silver-reinforced carbon fiber composite material.
[0013] As a biological reagent, dopamine can self-oxidize and polymerize on the carbon fiber surface to form a polydopamine film layer. This layer has certain reducing and hydrophilic properties of catechol, which can adsorb metal Ag. + And it is directly reduced to Ag particles loaded on the surface of carbon fiber. If dopamine is not added, silver nanoparticles cannot be formed. At present, with the widespread application of a new generation of wearable electronic products, higher requirements are placed on electromagnetic shielding materials in terms of lightness, flexibility, and stability. The method of treating carbon fiber with dopamine and then chemically plating silver is simple and environmentally friendly, and the prepared Ag / CFs is stable and does not fall off, showing good electromagnetic shielding effectiveness.
[0014] Further, in S1, the carbon fiber material is carbon fiber or carbon fiber cloth.
[0015] Furthermore, in S1, the mass ratio of the carbon fiber material to dopamine hydrochloride is 1:1-4.
[0016] Furthermore, in S1, the stirring reaction time is continued for 6 to 12 hours.
[0017] Furthermore, in S1, washing is also included after filtering, and the specific operation of washing is: washing with water at least once.
[0018] Further, in S2, the preparation of the silver ammonia solution is as follows:
[0019] To the aqueous silver nitrate solution, sodium hydroxide solution is added until a precipitate forms in the solution, and then aqueous ammonia is added until the solution becomes clear to obtain a silver ammonia solution.
[0020] Furthermore, the molar concentration of the sodium hydroxide solution is 0.1 to 1 mol / L.
[0021] Furthermore, the mass concentration of the silver nitrate aqueous solution is 2 to 10 g / L.
[0022] Furthermore, in S2, the chemical plating time is 30 to 60 minutes.
[0023] Further, in S2, the mass percentage of silver in the flexible silver-reinforced carbon fiber composite material is 10 to 66%.
[0024] The present invention also provides a flexible silver-reinforced carbon fiber composite material prepared by the method.
[0025] The present invention also provides a use of a flexible silver-reinforced carbon fiber composite material in electromagnetic interference shielding. Specifically, the flexible silver-reinforced carbon fiber composite material of the present invention can be applied to wearable sensors, flexible electronic devices and electromagnetic interference shielding materials.
[0026] Beneficial effects of the present invention:
[0027] 1. The present invention adopts simple dopamine active treatment and then chemical plating to prepare silver-enhanced carbon fiber composite material (Ag / CFs). Due to the advantages of enhanced interface reflection and reabsorption, the Ag / CFs has a high-efficiency EMI shielding effect (SE) of 50.12 dB and an excellent specific SE (SSE / t) of 1044.82 dB cm 2 / g.
[0028] 2. The flexible silver-reinforced carbon fiber composite material of the present invention exhibits excellent flexibility and stability. After bending 100 times, the EMI SE retention rate is 92%. The Ag / CFs prepared by the present invention can be applied to wearable sensors, flexible electronic devices and electromagnetic interference shielding materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 (a) for different Ag + XRD spectra of Ag / CFs samples prepared with high concentrations. Figure 1 (b) for different Ag + Raman spectrum of Ag / CFs samples prepared with high concentration. Figure 1 (c) for different Ag + XPS spectra of Ag / CFs samples prepared with high concentrations. Figure 1 (d) is the high-resolution XPS spectrum of Ag3d.
[0030] Figure 2 (a) is the SEM image of CFs. Figure 2 (b) SEM image of CFs activated by dopamine. Figure 2 (cf) for different Ag + SEM images of Ag / CFs samples prepared with high concentrations. Figure 2 (gk) is the EDS spectrum of Ag / CFs-10 sample.
[0031] Figure 3 EMI shielding performance test results. Among them, (a) is SE T Test results,(b)SE A Test results, (c)SE R Test results, (d)SE A ,SE R ,SE T Bar chart.
[0032] Figure 4 Ag / CFs-10 sample: (a) bending test, (b) lightweight properties, (c) SE after bending T Value, (d) Propagation of electromagnetic waves in Ag / CFs. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0034] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.
[0035] Here, we prepared Ag-reinforced carbon fiber composites (Ag / CFs) by simple dopamine activation treatment and chemical plating. The structure and morphology of Ag / CFs were characterized by XRD, Raman, XPS and SEM. + Effects of ion concentration and bending test on EMI shielding performance.
[0036] Example 1
[0037] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0038] S1. Preparation of Tris buffer solution:
[0039] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0040] S2. Preparation of silver ammonia solution
[0041] 0.2 g of silver nitrate was dissolved in 100 mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 2 g / L. Then, 0.1 mol / L of sodium hydroxide solution was added until the clear solution became turbid. Then, a small amount of ammonia water was added until the solution became clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0042] S3. Dopamine activation treatment of carbon fiber
[0043] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 1 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0044] S4, chemical silver plating
[0045] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs-2) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 2 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs-2).
[0046] Example 2
[0047] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0048] S1. Preparation of Tris buffer solution:
[0049] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0050] S2. Preparation of silver ammonia solution
[0051] 0.5 g of silver nitrate was dissolved in 100 mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 5 g / L. Then, 0.1 mol / L of sodium hydroxide solution was added until the clear solution became turbid. Then, a small amount of ammonia water was added until the solution became clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0052] S3. Dopamine activation treatment of carbon fiber
[0053] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 1 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0054] S4, chemical silver plating
[0055] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs-5) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 5 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs-5).
[0056] Example 3
[0057] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0058] S1. Preparation of Tris buffer solution:
[0059] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0060] S2. Preparation of silver ammonia solution
[0061] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0062] S3. Dopamine activation treatment of carbon fiber
[0063] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 1 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0064] S4, chemical silver plating
[0065] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs-10) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs-10).
[0066] Example 4
[0067] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0068] S1. Preparation of Tris buffer solution:
[0069] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0070] S2. Preparation of silver ammonia solution
[0071] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0072] S3. Dopamine activation treatment of carbon fiber
[0073] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 2 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0074] S4, chemical silver plating
[0075] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs-10) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs-10).
[0076] Example 5
[0077] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0078] S1. Preparation of Tris buffer solution:
[0079] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0080] S2. Preparation of silver ammonia solution
[0081] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0082] S3. Dopamine activation treatment of carbon fiber
[0083] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 3 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0084] S4, chemical silver plating
[0085] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag +The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0086] Example 6
[0087] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0088] S1. Preparation of Tris buffer solution:
[0089] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0090] S2. Preparation of silver ammonia solution
[0091] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0092] S3. Dopamine activation treatment of carbon fiber
[0093] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 4 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0094] S4, chemical silver plating
[0095] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0096] Example 7
[0097] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0098] S1. Preparation of Tris buffer solution:
[0099] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0100] S2. Preparation of silver ammonia solution
[0101] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0102] S3. Dopamine activation treatment of carbon fiber
[0103] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 5 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0104] S4, chemical silver plating
[0105] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0106] Example 8
[0107] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0108] S1. Preparation of Tris buffer solution:
[0109] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0110] S2. Preparation of silver ammonia solution
[0111] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2]OH).
[0112] S3. Dopamine activation treatment of carbon fiber
[0113] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 0.1 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The CFs was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0114] S4, chemical silver plating
[0115] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0116] Example 9
[0117] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0118] S1. Preparation of Tris buffer solution:
[0119] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0120] S2. Preparation of silver ammonia solution
[0121] Dissolve 1g of silver nitrate in 100mL of deionized water to prepare a silver nitrate aqueous solution with a mass concentration of 10g / L. Then add 0.1mol / L of sodium hydroxide solution until the clear solution becomes turbid. Then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0122] S3. Dopamine activation treatment of carbon fiber
[0123] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 2 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 8 h. The mixture was filtered, washed repeatedly with deionized water for 3 times, and then dried at 60 ° C to obtain a carbon fiber material activated with dopamine.
[0124] S4, chemical silver plating
[0125] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 10 g / L and dispersing the mixture evenly, then chemically plating the mixture for 30 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0126] Example 10
[0127] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0128] S1. Preparation of Tris buffer solution:
[0129] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0130] S2. Preparation of silver ammonia solution
[0131] Dissolve 0.3 g of silver nitrate in 100 mL of deionized water to prepare a 3 g / L silver nitrate aqueous solution, then add 0.5 mol / L of sodium hydroxide solution until the clear solution becomes turbid, then add a small amount of ammonia water until the solution becomes clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0132] S3. Dopamine activation treatment of carbon fiber
[0133] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 1 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 6 h. The mixture was filtered, washed repeatedly with deionized water for 1 to 3 times, and then dried at 60°C to obtain a carbon fiber material activated with dopamine.
[0134] S4, chemical silver plating
[0135] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 3 g / L and dispersing the mixture evenly, then chemically plating the mixture for 50 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0136] Embodiment 11
[0137] A method for preparing a flexible silver-reinforced carbon fiber composite material comprises the following steps:
[0138] S1. Preparation of Tris buffer solution:
[0139] 0.3 g of Tris was dissolved in 250 mL of deionized water, and an appropriate amount of concentrated hydrochloric acid (36-38% wt.) was added to control the pH value to about 8.5 to prepare a Tris buffer solution.
[0140] S2. Preparation of silver ammonia solution
[0141] 0.8 g of silver nitrate was dissolved in 100 mL of deionized water to prepare an aqueous silver nitrate solution with a mass concentration of 8 g / L. Then, 1 mol / L of sodium hydroxide solution was added until the clear solution became turbid. Then, a small amount of ammonia water was added until the solution became clear again to prepare a silver ammonia solution ([Ag(NH 3 ) 2 ]OH).
[0142] S3. Dopamine activation treatment of carbon fiber
[0143] 1 g of carbon fiber material (CFs) was added to 100 mL of Tris buffer solution at room temperature and magnetically stirred for 30 min. Then, 1 g of dopamine hydrochloride was added under stirring, and the stirring reaction was continued for 12 h. The CFs was filtered, washed repeatedly with deionized water for 1 to 3 times, and then dried at 60°C to obtain a carbon fiber material activated with dopamine.
[0144] S4, chemical silver plating
[0145] The carbon fiber material activated by dopamine was immersed in a silver ammonia solution (Ag + The silver-reinforced carbon fiber composite material (Ag / CFs) was obtained by mixing the silver-reinforced carbon fiber with a concentration of 8 g / L and dispersing the mixture evenly, then chemically plating the mixture for 60 min, filtering the mixture, washing the mixture with deionized water, and then filtering the mixture to obtain a flexible silver-reinforced carbon fiber composite material (Ag / CFs).
[0146] Next, we conduct performance test analysis on the flexible silver-reinforced carbon fiber composite materials (Ag / CFs) prepared in the above examples. The performance of the composite materials of Examples 10 to 11 is parallel to that of Example 1. Therefore, only the composite materials of Examples 1 to 9 and Comparative Example 1 are compared and analyzed.
[0147] 1. Different Ag + Analysis of Ag / CFs samples prepared by concentration
[0148] For comparison, we use Ag + Flexible silver-reinforced carbon fiber composite materials were prepared with concentrations of 2 g / L, 5 g / L and 10 g / L, and were named Ag / CFs-2 (Example 1), Ag / CFs-5 (Example 2), and Ag / CFs-10 (Example 3) respectively.
[0149] 1.1 XRD analysis
[0150] For different Ag prepared in Examples 1 to 3 + The XRD analysis of Ag / CFs samples with different concentrations is shown in Figure 1 (a).
[0151] Figure 1 (a) for different Ag + XRD patterns of Ag / CFs samples prepared with high concentrations.
[0152] from Figure 1 As can be seen in (a), a broad diffraction peak can be observed at 24°, corresponding to the (002) crystal plane of the carbon material. In addition, obvious diffraction peaks appear at 2θ of 38.04°, 44.19°, 64.43°, 77.36° and 81.56°, corresponding to the (111), (200), (220), (311) and (222) crystal planes of Ag, respectively. It can be concluded that as Ag + With the increase of concentration, the amount of silver loaded on the surface of carbon material also gradually increases, which also shows that carbon fiber activated by dopamine can promote the loading of silver.
[0153] 1.2 Raman spectroscopy analysis
[0154] For different Ag prepared in Examples 1 to 3 + The Raman spectroscopy analysis of Ag / CFs samples with different concentrations is shown in Figure 1 (b).
[0155] Figure 1 (b) for different Ag + Raman spectrum of Ag / CFs samples prepared with high concentration.
[0156] Figure 1 (b) shows that the typical Raman characteristic peak appears at 1360 cm -1 , 1580cm -1 At , it corresponds to the D peak and G peak of carbon material. The D peak represents the defect of C atom lattice, and the G peak represents the SP of C atom. 2 Hybrid in-plane stretching vibration.
[0157] Table 1 Different Ag + I of Ag / CFs samples with different concentrations G / I D Value comparison results
[0158] Example <![CDATA[Ag + Concentration]]> Sample <![CDATA[I G Value]]> <![CDATA[I D Value]]> <![CDATA[I G / I D value]]> 1 2g / L Ag / CFs-2 1944.97 1774.76 1.10 2 5g / L Ag / CFs-5 1774.30 1697.65 1.05 3 10g / L Ag / CFs-10 1907.20 1650.27 1.16
[0159] Note: I G The value is the intensity of the G peak; I D The value is the intensity of peak D; I G / I DThe value is the ratio of the intensity of the G peak to the intensity of the D peak, which is used to indicate relevant information such as the degree of graphitization of carbon materials.
[0160] The results show that the I of Ag / CFs-10 prepared in Example 3 G / I D The value is higher than that of other samples. This shows that the Ag / CFs-10 sample prepared in Example 3 has a relatively high degree of graphitization, and a higher degree of graphitization is conducive to obtaining better electrical conductivity, which further demonstrates that the Ag / CFs-10 sample prepared in Example 3 has relatively good electrical conductivity.
[0161] 1.3 XPS spectral analysis
[0162] The XPS spectrum analysis of the Ag / CFs-10 sample prepared in Example 3 shows Figure 1 (c) and (d).
[0163] Figure 1 (c) is the XPS measurement spectrum of Ag / CFs-10 sample. Figure 1 (d) is the high-resolution XPS spectrum of Ag3d.
[0164] like Figure 1 As shown in (c) and (d), Ag / CFs-10 sample has Ag 3d at 368.8eV and 374.5eV, respectively. 5 / 2 and Ag 3d 3 / 2 The characteristic peaks of Ag / CFs-10 were obtained, which indicated that Ag / CFs-10 was successfully prepared.
[0165] We also performed XPS spectral analysis on the samples of Example 1 and Example 2, and observed Ag 3d 5 / 2 and Ag 3d 3 / 2 The characteristic peaks of + The corresponding Ag / CFs samples were successfully prepared with a high concentration, which further verified that carbon fibers activated by dopamine can promote the loading of silver.
[0166] 1.4 SEM analysis
[0167] For different Ag prepared in Examples 1 to 3 + The Ag / CFs samples with different concentrations were subjected to SEM (scanning electron microscope) analysis to observe the microstructure of the samples. The results are shown in Figure 2 .
[0168] Figure 2 (a) is the SEM image of CFs (carbon fiber material). Figure 2(b) SEM image of CFs treated with dopamine activity.
[0169] from Figure 2 (a) It can be seen that the original carbon fiber (CFs) has a smooth surface and a diameter of about 50 μm. After the dopamine active treatment, a thin layer of polydopamine film is formed on the surface of the carbon fiber (see Figure 2 (b)), which is Ag + In situ reduction to Ag particles provides a large number of active sites.
[0170] Figure 2 (c) is the SEM image of the Ag / CFs-2 sample prepared in Example 1. Figure 2 (d) is the SEM image of the Ag / CFs-5 sample prepared in Example 2. Figure 2 (e) is the SEM image of the Ag / CFs-10 sample prepared in Example 3. Figure 2 (f) Figure 2 (e) A partial enlarged view.
[0171] Figure 2 (c) to (f) show different concentrations of Ag + The microstructure of the prepared Ag / CFs. It was observed that a layer of silver particles was tightly attached to the surface of the carbon fiber, and along with the Ag + With the increase of concentration, the silver particles gradually increase in size, and the modification of the carbon fiber surface becomes more uniform. Figure 2 (c) to (f) it can be seen that the prepared Ag / CFs has a three-dimensional network structure, which can provide more interface reflection and scattering of electromagnetic waves. This also shows that the Ag / CFs prepared in the embodiment of the present invention can be applied to wearable sensors, flexible electronic devices and electromagnetic interference shielding materials.
[0172] Figure 2 (g) to (k) are SEM images and EDS spectra of the Ag / CFs-10 sample prepared in Example 3.
[0173] Depend on Figure 2 The SEM images and EDS spectra in (g) to (k) further show that the C, O and Ag elements are uniformly distributed in the Ag / CFs-10 sample, with the mass percentage being 27.43:6.21:66.36.
[0174] Table 2 Different Ag + The proportion of C, O and Ag elements in Ag / CFs samples with different concentrations
[0175] Example <![CDATA[Ag + Concentration]]> Sample Ag element / wt% C element / wt% O element / wt% 1 2g / L Ag / CFs-2 10.72 77.10 12.18 2 5g / L Ag / CFs-5 38.47 52.38 9.15 3 10g / L Ag / CFs-10 66.36 27.43 6.21
[0176] From the results in Table 2, we can see that with the increase of Ag +With the increase of concentration, the amount of silver loaded on the surface of carbon material also gradually increases, which also shows that carbon fiber activated by dopamine can promote the loading of silver, which further verifies the results of XRD analysis.
[0177] 2. Analysis of Ag / CFs samples prepared with different dopamine dosages
[0178] For comparison, we prepared flexible silver-reinforced carbon fiber composites (Ag / CFs) with dopamine (DA) in amounts ranging from 0.1 g to 5 g, and studied the effects of different amounts of dopamine on the silver loading and flexibility of the carbon materials.
[0179] During the test, it was found that if the amount of dopamine added was too little (<1g, Examples 8-9), the amount of silver loaded on the surface of the carbon material would also decrease, and sufficient silver particle loading sites could not be provided. As the amount of dopamine added increased (1-5g, Examples 3-7), a dense polydopamine coating was formed on the surface of the carbon fiber, and the amount of silver loaded tended to increase slightly with the increase in the amount of dopamine added, and the size of the surface silver crystals increased.
[0180] However, with the increase of dopamine dosage, the single fiber tensile strength of the Ag / CFs sample gradually decreased, and when the dopamine dosage was 5g, the single fiber tensile strength of the Ag / CFs sample decreased the most. Therefore, taking all factors into consideration, the silver loading and flexibility of the flexible silver reinforced carbon fiber composite material are optimal when the mass ratio of carbon fiber material to dopamine hydrochloride is 1:1-4.
[0181] 3. EMI shielding performance analysis
[0182] According to the Sherkunov theory, the electromagnetic interference shielding effectiveness (SE T ) including absorption loss (SE A ), reflection loss (SE R ), multiple reflection loss (SE M ), and calculated as follows:
[0183] SE T (dB) = SE A +SE R +SE M ≈SE A +SE R (1)
[0184] SE A (dB) = -10log[S 21 2 / (1-S 11 2 )] (2)
[0185] SER (dB) = -10log(1-S 11 2 ) (3)
[0186] Among them, S 11 and S 22 is the reflection coefficient, S 12 and S 21 is the absorption coefficient. When SE T ≥15dB, SE M Usually can be ignored.
[0187] Figure 3 The EMI shielding performance test results are shown in Figure 2. Among them, (a) is the different Ag prepared in Examples 1 to 3. + The electromagnetic interference shielding effectiveness (SE) of Ag / CFs samples with different concentrations T ) Test results. (b) The different Ag prepared in Examples 1 to 3 + The absorption loss of Ag / CFs samples with different concentrations (SE A ) Test results. (c) The different Ag prepared in Examples 1 to 3 + The reflection loss (SE R ) Test results. (d) is the test results of different Ag prepared in Examples 1 to 3 + SE of Ag / CFs samples with different concentrations A ,SE R ,SE T Bar chart.
[0188] right Figure 3 Analysis shows that in Figure 3 In (d), the EMI SE value of the original carbon fiber (CFs) is relatively low, which is 25.38 dB. + With the increase of Ag concentration, the EMI SE value gradually increases, which shows that chemical silver plating helps to improve the EMI shielding performance of Ag / CFs composites. + When the concentration is 10 g / L, the EMI SE value reaches a maximum and can reach 50.12 dB, which indicates that 99.9% of the incident electromagnetic wave radiation can be attenuated.
[0189] Figure 3 (a) to (c) show the electromagnetic shielding performance of CFs and Ag / CFs at 8.2 to 12.4 GHz (X band). Figure 3 (b) and (c) show that the absorption loss SE A It is a reflection SE RThis result further confirms the absorption-dominated shielding mechanism of Ag / CFs, which can reduce the harm of secondary radiation electromagnetic waves.
[0190] It is worth noting that in this work, Ag / CFs exhibited a significant EMI shielding ratio (SSE / t value) of 1044.82 dB cm 2 / g. The high efficiency of electromagnetic shielding performance of the composite material is mainly attributed to the synergistic effect between Ag and CFs. On the one hand, the introduction of silver particles provides a higher conductivity of the three-dimensional network carbon fiber, and on the other hand, the prepared Ag / CFs attenuates electromagnetic waves through multiple interface reflections and secondary absorption.
[0191] 4. Bending test
[0192] In order to test the flexibility of Ag / CFs, bending tests were performed on the Ag / CFs samples.
[0193] Taking the Ag / CFs-10 sample prepared in Example 3 as an example, the Ag / CFs-10 sample prepared in Example 3 was bent 20 times, 50 times, and 100 times, respectively, and then recovered to test its electromagnetic shielding value.
[0194] Figure 4 The process and results of the bending test of the Ag / CFs-10 sample prepared in Example 3. (a) is the test process of the bending test of the Ag / CFs-10 sample. (b) is the test process of the lightweight characteristics of the Ag / CFs-10 sample. (c) is the SE of the Ag / CFs-10 sample after bending 20 times, 50 times, and 100 times. T (d) is the principle diagram of electromagnetic wave propagation in Ag / CFs-10 sample.
[0195] Depend on Figure 4 (b) It can be seen that Ag / CFs-10 has obvious lightweight properties.
[0196] Depend on Figure 4 The results of (a) and (c) show that Ag / CFs-10 exhibits excellent flexibility and stability. After bending 100 times, the EMI SE is 46.10 dB and the retention rate is 92%. The main reason is that the polydopamine film in the experiment provides a strong interface interaction for the silver particles to tightly load the carbon fiber, which is conducive to obtaining stable electromagnetic shielding performance. This further proves that the Ag / CFs prepared in the embodiment of the present invention well meets the higher requirements of the new generation of electronic products in terms of light weight, flexibility, and efficient EMI shielding characteristics.
[0197] In summary, lightweight and flexible Ag / CFs with high electromagnetic shielding performance were prepared by activating carbon fibers with dopamine and then chemically plating Ag on the surface. Due to multiple reflections and absorption of electromagnetic waves, Ag / CFs showed a high EMI SE of 50.12 dB and an excellent EMI shielding ratio (SSE / t value) of 1044.82 dB cm 2 / g. In particular, Ag / CFs also exhibits excellent flexibility and stability. After 100 bends, the EMI SE is 46.10 dB, and the retention rate is 92%. Therefore, the Ag / CFs prepared in the embodiment of the present invention will become an ideal electromagnetic interference shielding material in the application environment of a new generation of flexible wearable electronic products.
[0198] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing a flexible silver-reinforced carbon fiber composite material, It is characterized in that The following steps are involved: S1. placing the carbon fiber material in a Tris buffer solution, then adding dopamine hydrochloride under stirring, continuing to stir the reaction, filtering, and obtaining a carbon fiber material treated with dopamine activity; S2. Immersing the carbon fiber material treated with dopamine activity into a silver ammonia solution for chemical plating, filtering, and obtaining a flexible silver-reinforced carbon fiber composite material.
2. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 1, It is characterized in that In S1, the carbon fiber material is carbon fiber or carbon fiber cloth.
3. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 1, It is characterized in that In S1, the mass ratio of the carbon fiber material to dopamine hydrochloride is 1:1-4.
4. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 1, It is characterized in that In S1, the stirring reaction time is continued for 6 to 12 hours.
5. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 1, It is characterized in that In S2, the silver ammonia solution is prepared as follows: To the aqueous silver nitrate solution, sodium hydroxide solution is added until a precipitate forms in the solution, and then aqueous ammonia is added until the solution becomes clear to obtain a silver ammonia solution.
6. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 5, It is characterized in that The molar concentration of the sodium hydroxide solution is 0.1 to 1 mol / L; The mass concentration of the silver nitrate aqueous solution is 2 to 10 g / L.
7. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 1, It is characterized in that In S2, the chemical plating time is 30 to 60 minutes.
8. The method for preparing the flexible silver-reinforced carbon fiber composite material according to claim 1, It is characterized in that In S2, the mass percentage of silver in the flexible silver-reinforced carbon fiber composite material is 10-66%.
9. A flexible silver-reinforced carbon fiber composite material prepared by the method according to any one of claims 1 to 8.
10. Use of the flexible silver-reinforced carbon fiber composite material according to claim 9 in electromagnetic interference shielding.