CN107164820A - A kind of highly oriented composite conducting nanofiber - Google Patents

Abstract

The invention relates to a highly oriented conductive nanofiber, which is prepared by the following method: dissolving PET and a metal salt in a solvent and mixing them, adding modified carboxyl-grafted multi-walled carbon nanotubes, and ultrasonically dispersing to obtain a spinning solution, wherein : The mass percentages of metal salt, PET, solvent and carbon nanotubes are respectively: 10‐20%, 10‐20%, 60‐70%, 5‐10%; the spinning solution is subjected to electrospinning treatment: spinning The wire voltage is 10-50kv, the auxiliary electrode voltage is 10-30kv, the receiving distance is 10-30cm, the drum speed is 200-1000rpm, and the injection rate is 0.1-10ml/h. After heat treatment, the obtained conductive fibers are prepared into highly oriented conductive nanofibers. The invention has high electrical conductivity while ensuring the mechanical strength of the fiber membrane, and has good industrialization prospects.

Description

A highly oriented composite conductive nanofiber

technical field

The invention relates to a highly oriented composite conductive nanofiber, in particular to a highly oriented PET/CNTs-based composite conductive nanofiber prepared by improving the orientation of the nanofiber and adopting electrospinning technology. It belongs to the technical field of electrostatic spinning.

technical background

Conductive polymer material is a kind of functional material with conductivity close to that of metal or semiconductor. Compared with metal or semiconductor, it has the advantages of light weight, low production cost, and easy processing. Among them, conductive nanofibers have ultra-high specific surface area. , large aspect ratio and excellent conductivity, it has broad application prospects in energy, electronics, biology and other fields.

Polyethylene terephthalate (PET) is one of the most important engineering plastics at present. It has excellent mechanical properties, high impact strength, wear resistance, creep resistance, and excellent physical properties. Excellent chemical resistance, excellent electrical insulation, high heat resistance and high rigidity, high hardness, low water absorption and good dimensional stability after fiber reinforcement, widely used in food packaging and fiber field. However, PET itself has some defects. The strength of nanofibers prepared from pure PET spinning solution is not high, and its heat resistance, weather resistance and fatigue resistance are poor, and because it is an insulator, its electrical conductivity is poor.

Carbon nanotubes (CNTs) are one-dimensional tubular carbon molecules. Each carbon atom on the tube adopts SP ² hybridization and is bonded to each other by carbon-carbon σ bonds to form a hexagonal honeycomb carbon nanoskeleton. . The diameter of carbon nanotubes is generally several nanometers to tens of nanometers, and the length is several micrometers to millimeters. They have strong surface effects, quantum size effects, high temperature resistance and electrical and thermal conductivity. They are widely used in many fields, such as super capacitors, storage Hydrogen materials, lithium-ion batteries, catalyst supports, etc. However, due to the very few surface active groups of carbon nanotubes and the large surface area, they are easy to agglomerate and entangle with each other, so it is difficult to disperse uniformly in the polymer, making it difficult to exert their excellent performance.

Electrospinning is a special fiber manufacturing process. Under the force of a strong electric field, the polymer solution or solution forms a sharp Taylor cone at the needle, and extends from the tip of the cone to obtain fiber filaments. Electrospinning is the most convenient and effective method for preparing nanofibers. It has the advantages of low cost, high controllability, and uniform fiber size. The nanofiber membrane prepared by electrospinning has the advantages of large specific surface area and small pores. It is widely used in Filter materials, medical devices, tissue engineering, liquid crystal materials, catalysts, etc. At present, although there are some reports on the preparation of conductive nanofibers by electrospinning technology, they are mainly limited to doping ions and metals. On the contrary, there are few reports on improving the conductivity of fiber membranes by improving the orientation of nanofibers.

Contents of the invention

In view of the shortcomings and deficiencies of the existing technology, the present invention adopts electrospinning technology, by adding auxiliary electrodes, and adding metal ions and modified carbon nanofibers to the spinning solution, and successfully prepares highly oriented PET/CNTs-based Composite conductive nanofibers. Experiments show that the conductive nanofibers not only have excellent electrical conductivity, but also have high mechanical strength, and have good application prospects.

The purpose of the present invention is to prepare a new type of highly oriented composite conductive nanofiber, the diameter of the obtained nanofiber is controllable, and the preparation method provided is relatively simple, the cost is low, and it has high electrical conductivity while ensuring the mechanical strength of the fiber membrane. It has a good industrialization prospect.

In order to solve the above technical problems, the present invention provides the following solutions:

A highly oriented composite conductive nanofiber is characterized in that the highly oriented composite conductive nanofiber is prepared by the following method, the steps comprising:

(1) Dissolve polyethylene terephthalate (PET) in a solvent to form a stable solution a, then dissolve the metal salt in the solvent and disperse ultrasonically to form a stable solution b, and mix solution a and solution b to form a uniform Stable mixed solution, and add carbon nanotube suspension to obtain precursor, and ultrasonically disperse the precursor for 2-24 hours to obtain spinning solution, the weight of metal salt, PET, solvent and carbon nanotube in spinning solution The percentages are: 10-20%, 10-20%, 60-70%, 5-10%;

Wherein, the metal salt is zinc acetate or/and tetrabutyl titanate,

The solvent is selected from one or more of water, ethanol, acetic acid, phenol, trifluoroacetic acid, methylene chloride, dimethylformamide,

The carbon nanotubes are carboxyl-grafted multi-walled carbon nanotubes with a grafting rate of 3.84%;

(2): The spinning solution prepared in step (1) is subjected to electrospinning treatment to obtain highly oriented nanofibers, which are dried in a drying oven at 20-100° C., wherein the spinning voltage during electrospinning treatment is 10-50kv, auxiliary electrode voltage 10-30kv, receiving distance 10-30cm, drum speed 200-1000rpm, injection rate 0.1-10ml/h;

(3): heat-treating the highly oriented nanofibers prepared in step (2) to obtain the highly oriented composite conductive nanofibers.

The preferred heat treatment temperature in step (3) is 10-500° C., and the heat treatment time is 1-100 h.

The electrospinning processing device of the present invention includes: a syringe for injecting spinning liquid, a nozzle at the front end of the syringe, a drum receiver covered with aluminum foil, the positive and negative poles of the high-voltage power supply are respectively connected to the spinneret and the aluminum foil, and the nozzle and the drum receiver A pair of auxiliary electrodes parallel up and down are arranged between them, and the auxiliary electrodes are connected to a high-voltage power supply.

The electrical conductivity of the conductive nanofibers was analyzed using a resistance meter. Test method: cut conductive nanofibers into 20mm×20mm small slices, coat silver electrodes on the glaze surface at both ends, ensure that the area to be tested between the electrodes is a square, and test the surface resistance of the sample with a resistance meter; test conditions: room temperature 25°C, Air humidity 30%.

The morphology of the conductive nanofibers was analyzed by scanning electron microscopy (SEM). Test conditions: sample cutting: 2mm×2mm, gold spraying time: 30s, ambient temperature: 25°C.

The orientation crystallinity of conductive nanofibers was analyzed by X-ray diffraction (XRD). Test conditions: scanning speed: 8°/min, scanning mode: 2theta, scanning method: continue.

Thermal analysis of the conductive nanofibers was carried out by differential scanning calorimetry (DSC). Test conditions: temperature range: 25-300°C, heating rate: 10°C/min, protective atmosphere: N ₂ protection.

The mechanical properties of conductive nanofibers were analyzed using a miniature universal tensile machine. Test conditions: sample size 50mm×10mm×0.25mm, tensile rate 10mm/min.

The tensile strength of the product obtained after molding the highly oriented conductive nanofiber material of the present invention is 1.0-3MPa.

The average fiber diameter of the product obtained after molding the highly oriented conductive nanofiber material of the present invention is about 500nm, and the conductivity is between 10 ³ -10 ⁷ Ω.

The invention improves the electrical conductivity of the fiber membrane by improving the orientation of the nanofibers, while ensuring better mechanical properties of the fiber membrane. In addition, the added metal salt can form a doped structure with the carbon nanotubes to further improve the electrical conductivity of the fiber membrane. Compared with traditional conductive nanofibers, the conductive nanofibers of the present invention have better mechanical strength and durability. At the same time, due to the high spinnability of the PET solution, the preparation process is relatively simple, which is more conducive to industrial application.

Description of drawings

Fig. 1 is the optical microscope photograph of conductive nanofiber membrane, among the figure: a is the PET nanofiber membrane topography figure among the comparative example 1; B is the PET/CNTs nanofiber membrane topography figure among the comparative example 3; C is the implementation Topography of PET/CNTs/zinc ion doped nanofiber membrane in Example 3.

Fig. 2 is the scanning electron micrograph of conductive nanofibrous film, among the figure: a is the PET nanofibrous film topography figure in comparative example 1, a ' is a local enlarged view; b is PET/CNTs nanofiber in comparative example 3 The topography of the fiber membrane, b' is a partial enlarged view of b; c is the topography of the PET/CNTs/zinc ion-doped nanofiber membrane in Example 3, and c' is a partial enlarged view of c.

Fig. 3 is the X-ray diffraction spectrogram of conductive nanofiber film, and a is PET spectrogram in comparative example 1; B is PET/CNTs spectrogram in comparative example 3; C is PET/CNTs/zinc ion in embodiment 3 Doped nanofiber spectrum; d is the PET/CNTs/titanium ion doping spectrum in Example 4.

Figure 4 is an electrospinning treatment device.

Among them, 1. Syringe pump; 2. Auxiliary electrode; 3. Roller receiving device; 4. High voltage power supply U1; 5. High voltage power supply U2; 6. Ground wire

detailed description

The present invention will be further elaborated below by embodiment.

Comparative example 1

A kind of conductive nanofiber, take PET as matrix, specifically as follows:

(1) Dissolve 0.85g of PET in a solution of trifluoroacetic acid and dichloromethane with a volume ratio of 6:4 to prepare a solution (spinning solution) with a PET content of 10%.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative poles of the high-voltage power supply to the spinneret and the aluminum foil respectively. The electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the nanofibers are received by the static receiving device, and the spinning is advanced at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

The fully dried nanofiber membrane was put into a muffle furnace and heat-treated at 240°C for 50 minutes to obtain conductive nanofibers. The measured volume resistivity was 5.6×10 ¹⁴ Ω·cm, and the tensile strength was 0.75Mpa. It is characterized by a completely disordered structure, and XRD has obvious diffraction peaks at 15-20°, indicating that the fiber still has a certain degree of crystallinity.

Comparative example 2

(1) Dissolve 0.85g of PET in a solution of trifluoroacetic acid and dichloromethane with a volume ratio of 6:4 to prepare a solution with a PET content of 10%.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative poles of the high-voltage power supply to the spinneret and the aluminum foil respectively. The electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the nanofibers are received by the drum receiving device, the drum rotation speed is 600rpm, the spinning is advanced at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

The fully dried nanofiber membrane was placed in a muffle furnace and heat-treated at 240°C for 50 minutes to obtain conductive nanofibers with a measured volume resistivity of 7.2×10 ¹³ Ω·cm and a tensile strength of 0.79Mpa.

Comparative example 3

A highly oriented composite conductive nanofiber film, with PET as a matrix, and carboxyl-grafted multi-walled carbon nanotubes with a grafting rate of 3.84% as a modified body, the details are as follows:

(1) Dissolve 0.85g of PET in trifluoroacetic acid and dichloromethane solution with a volume ratio of 6:4 to prepare a solution with a PET content of 10%, then add 0.1mg of multi-walled carbon nanotubes, continue stirring for 5h, and finally The solution was ultrasonically dispersed for 1 h to obtain a spinning solution.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative poles of the high-voltage power supply to the spinneret and the aluminum foil respectively. The electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the rotating speed of the drum is 600rpm, the spinning is promoted at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

(3) Put the fully dried nanofiber membrane into a muffle furnace and heat-treat it at 240°C for 50 minutes to obtain the physical picture shown in (b) in Figure 1. The volume resistivity of the conductive nanofiber is 8.7× 10 ⁷ Ω·cm, the tensile strength is 1.74Mpa, the SEM morphology is characterized by a locally ordered structure, and the XRD diffraction peak at 15-20° is obviously weakened, indicating that the fibers form a certain orientation and inhibit their crystallization.

Example 1

A kind of highly oriented composite conductive nanofiber film of the present invention, take PET as substrate, zinc acetate is metal ion, the carboxyl grafted multi-walled carbon nanotube of graft rate 3.84% is modified body, specifically as follows:

(1) Dissolve 0.85g PET in trifluoroacetic acid and dichloromethane solution with a volume ratio of 6:4 to prepare a solution a with a PET content of 10%; dissolve 0.25g zinc acetate in absolute ethanol and ultrasonically disperse 2h to form a uniform and stable solution b; mix solution a and solution b at a ratio of 10:1 and stir under magnetic stirring for 24h to form a uniform and transparent solution, and then add 0.1mg of carboxyl grafted polysaccharide with a grafting rate of 3.84% wall carbon nanotubes, continue stirring for 5 hours, and finally ultrasonically disperse the solution for 1 hour to obtain a spinning solution.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative electrodes of the high-voltage power supply to the spinneret and the aluminum foil respectively, and the electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the rotating speed of the drum is 600rpm, the spinning is promoted at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

(3) Put the fully dried nanofiber membrane into a muffle furnace and heat-treat at 240°C for 50 minutes to obtain a conductive nanofiber membrane. The measured volume resistivity of the conductive nanofiber is 2.1×10 ⁶ Ω·cm. The tensile strength is 2.18Mpa.

Example 2

A kind of highly oriented composite conductive nanofiber film of the present invention, take PET as substrate, zinc acetate is metal ion, the carboxyl grafted multi-walled carbon nanotube of graft rate 3.84% is modified body, specifically as follows:

(1) 0.85g PET is dissolved in trifluoroacetic acid and dichloromethane solution that volume ratio is 6:4, is mixed with the solution a that PET content is 10%; With 0.25g zinc acetate, 2ml glacial acetic acid is dissolved in volume ratio In a 1:1 mixed solution of ethanol and dimethylformamide, stir at room temperature for 24 hours to form a uniform and stable solution b; mix solution a and solution b at a ratio of 3:1 and stir for 24 hours, then add 0.1 mg of grafted Carboxyl-grafted multi-walled carbon nanotubes with a rate of 3.84% were stirred for 5 hours, and finally the solution was ultrasonically dispersed for 1 hour to obtain a spinning solution.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative poles of the high-voltage power supply to the spinneret and the aluminum foil respectively. The electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the auxiliary voltage is 10kv, the drum rotation speed is 600rpm, the spinning is advanced at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

(3) Put the fully dried nanofiber membrane into a muffle furnace and heat-treat at 240°C for 50 minutes to obtain a conductive nanofiber membrane. The measured volume resistivity of the conductive nanofiber is 6.4×10 ⁴ Ω·cm. The tensile strength is 2.47Mpa.

Example 3

A kind of highly oriented composite conductive nanofiber film of the present invention, take PET as substrate, zinc acetate is metal ion, the carboxyl grafted multi-walled carbon nanotube of graft rate 3.84% is modified body, specifically as follows:

(1) 0.85g PET is dissolved in trifluoroacetic acid and dichloromethane solution that volume ratio is 6:4, is mixed with the solution a that PET content is 10%; With 0.25g zinc acetate, 2ml glacial acetic acid is dissolved in volume ratio In a 1:1 mixed solution of ethanol and dimethylformamide, stir at room temperature for 24 hours to form a uniform and stable solution b; mix solution a and solution b at a ratio of 3:1 and stir for 24 hours, then add 0.5 mg of grafting The multi-walled carbon nanotubes were grafted with 3.84% carboxyl groups, the stirring was continued for 5 hours, and finally the solution was ultrasonically dispersed for 1 hour to obtain a spinning solution.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative poles of the high-voltage power supply to the spinneret and the aluminum foil respectively. The electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the auxiliary voltage is 10kv, the rotating speed of the drum is 600rpm, the spinning is advanced at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

(3) Put the fully dried nanofiber membrane into a muffle furnace and heat-treat it at 240°C for 50 minutes to obtain a conductive nanofiber membrane. The measured volume resistivity of the conductive nanofiber is 3.5×10 ⁴ Ω·cm. The tensile strength is 2.33Mpa, the SEM morphology is characterized by a highly ordered structure, and the XRD diffraction peak almost disappears at 15-20°, indicating that the fibers are highly oriented at this time, and the crystallization characteristics completely disappear.

Example 4

A highly oriented composite conductive nanofiber film of the present invention uses PET as a matrix, tetrabutyl titanate as a metal ion, and carboxyl-grafted multi-walled carbon nanotubes with a grafting rate of 3.84% as a modified body, specifically as follows:

(1) Dissolve 0.85g PET in trifluoroacetic acid and dichloromethane solution with a volume ratio of 6:4 to prepare a solution a with a PET content of 10%; dissolve 0.4g tetrabutyl titanate and 2ml glacial acetic acid in In a mixed solution of ethanol and dimethylformamide with a volume ratio of 1:1, stir at room temperature for 24 hours to form a uniform and stable light yellow solution b; mix solution a and solution b at a ratio of 3:1 and stir for 24 hours, then Add 0.5 mg of carboxyl-grafted multi-walled carbon nanotubes with a grafting rate of 3.84%, continue stirring for 5 h, and finally ultrasonically disperse the solution for 1 h to obtain a spinning solution.

(2) Pour 10ml of spinning solution into the syringe, and wrap the aluminum foil on the drum receiver, connect the positive and negative poles of the high-voltage power supply to the spinneret and the aluminum foil respectively. The electrospinning parameters are as follows: the diameter of the nozzle is 0.6mm, and the nozzle The distance to the receiver is 15cm, the spinning voltage is 25kv, the auxiliary voltage is 10kv, the drum rotation speed is 600rpm, the spinning is advanced at a speed of 0.6ml/h, and the spinning time is 4h. Put the aluminum foil collected with the nanofibrous membrane into a vacuum drying oven to dry for 24 h.

(3) Put the fully dried nanofiber membrane into a muffle furnace and heat-treat it at 240°C for 50 minutes to obtain a conductive nanofiber membrane. The measured volume resistivity of the conductive nanofiber is 5.9×10 ⁵ Ω·cm. The tensile strength is 2.13Mpa.

Claims (2)

1. A highly oriented composite conductive nanofiber is characterized in that, described highly oriented composite conductive nanofiber is made by the following method, and its steps comprise: (1) Dissolve polyethylene terephthalate (PET) in a solvent to form a stable solution a, then dissolve the metal salt in the solvent and disperse ultrasonically to form a stable solution b, and mix solution a and solution b to form a uniform Stable mixed solution, and adding carbon nanotube suspension to obtain a precursor, ultrasonically dispersing the precursor for 2-24 hours to obtain a spinning solution, the mass of metal salt, PET, solvent and carbon nanotubes in the spinning solution The percentages are: 10‐20%, 10‐20%, 60‐70%, 5‐10%; Wherein, the metal salt is zinc acetate or/and tetrabutyl titanate, The solvent is selected from one or more of water, ethanol, acetic acid, phenol, trifluoroacetic acid, methylene chloride, dimethylformamide, The carbon nanotubes are carboxyl-grafted multi-walled carbon nanotubes with a grafting rate of 3.84%; (2): The spinning solution prepared in step (1) is subjected to electrospinning treatment to obtain highly oriented nanofibers, which are dried in a drying oven at 20-100°C, wherein the spinning voltage during electrospinning treatment is 10-50kv, auxiliary electrode voltage 10-30kv, receiving distance 10-30cm, drum speed 200-1000rpm, injection rate 0.1-10ml/h; (3): heat-treating the highly oriented nanofibers prepared in step (2) to obtain the highly oriented composite conductive nanofibers. 2. The highly oriented composite conductive nanofiber according to claim 1, characterized in that the heat treatment temperature in step (3) is 10-500°C, and the heat treatment time is 1-100h.