Patent Application
20140315020
The technical field relates to nano metal wire, and in particular, relates to a method for manufacturing the same.
Recently, nano technology is widely used in information technology, material technology, biotechnology, and the likes. When the size of a material is scaled down to nano scale, its properties will change according to its shape and size. For example, a silver nanorod or nanowire may have absorption peaks of longitudinal mode and traverse mode under surface plasmon resonance. The nanorod or nanowire with a larger aspect (length-diameter) ratio has a red-shifted absorption peak of longitudinal mode.
A silver nanowire or silver wire with a high aspect ratio has been disclosed by some research teams. However, the conventional silver nanowires have a length of several nanometers (nm) to several micrometers (μm), an aspect ratio of less than 1000 (or even less than 100), and low conductivity.
Accordingly, a novel method for preparing silver nanowires with high conductivity and a high aspect ratio is called-for.
One embodiment of the disclosure provides a method of manufacturing a nano metal wire, comprising: putting a metal precursor solution in a core pipe of a needle; putting a polymer solution in a shell pipe of the needle, wherein the shell pipe surrounds the core pipe; applying a voltage to the needle while simultaneously jetting the metal precursor solution and the polymer solution to form a nano line on a collector, wherein the nano line includes a metal precursor wire surrounded by a polymer tube; chemically reducing the metal precursor wire of the nano line to form a nano line of a nano metal wire surrounded by the polymer tube; and washing out the polymer tube by a solvent.
One embodiment of the disclosure provides a nano line, comprising: a metal precursor wire; and a polymer tube surrounding the metal precursor wire, wherein the metal precursor wire comprises a metal compound and a chemically reducing agent.
One embodiment of the disclosure provides a nano metal wire, having an aspect ratio of greater than 1000, and a conductivity of between 104 S/m to 107 S/m.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The disclosure can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
In the disclosure, a nano metal wire having a high aspect ratio (e.g. greater than 1000) is formed by an electrostatic spinning apparatus. As shown in
In one embodiment, a solvent of the polymer solution is an organic solvent with high-polarity such as methanol or acetone, and the corresponding polymer is polyvinylpyrrolidone (PVP). In addition, a salt such as tetrabutyl ammonium phosphate (TBAP) or cetyltrimethylammonium bromide (CTAB) can be optionally added into the polymer solution. The salt may enhance the polarization degree of the electrostatic spinning, thereby reducing the polymer amount.
In one embodiment, the additive amount of the salt is of about 1 mg/mL to 100 mg/mL. Alternatively, a solvent of the polymer solution can be an organic solvent with low-polarity such as tetrahydrofuran (THF), toluene, or chloroform. In this case, the corresponding polymer can be polyacrylonitrile (PAN), polyvinyl alcohol (PVA), or ethylene vinyl alcohol (EVA). If the solvent of the polymer solution is an organic solvent with high-polarity, it can be washed out by water to meet environmentally friendly requirements after the forming of a nano metal wire. If the solvent of the polymer solution is an organic solvent with low-polarity, the polymer solution and the metal precursor solution will be immiscible when forming the nano metal wire having a high quality. In one embodiment, the polymer in the polymer solution has a concentration of about 100 mg/mL to 200 mg/mL.
In one embodiment, the metal precursor solution includes a metal compound and chemically reducing agent. The metal compound can be a silver compound (e.g. silver nitrate or silver oxide), platinum compound (e.g. platinum chloride or platinous oxide), gold compound (e.g. gold chloride or auric acid), or combinations thereof. The selection of the chemically reducing agent depends on the metal compound type. For example, when the metal compound is silver nitrate, the chemically reducing agent can be ethylene glycol. When the metal compound is silver oxide, the chemically reducing agent can be ammonium hydroxide. When the metal compound is platinum chloride, the chemically reducing agent can be hydrazine, sodium hydroborate, hydrogen, or alcohol. When the metal compound is gold chloride, the chemically reducing agent can be an aqueous solution of sodium citrate or Vitamin C. The metal compound concentration depends on the metal compound type. For example, the silver nitrate has a concentration of about 1 mg/mL to 100 mg/mL, and the silver oxide has a concentration of about 1 mg/mL to 100 mg/mL. The chemically reducing agent concentration depends on the chemically reducing agent type. For example, the ethylene glycol may directly serve as an organic solvent with high-polarity, and the ammonium hydroxide may have a concentration of about 1 wt % to 50 wt %.
In one embodiment, the core pipe 15I of the needle 15 has a diameter of about 0.5 m to 2 mm, which is determined by the desired diameter of the nano metal wire. In one embodiment, the shell pipe 15O and the core pipe 15I of the needle 15 have a difference of about 0.01 mm to 5 mm.
In one embodiment, the voltage applied to the needle 15 is about 10 kV to 12 kV. In one embodiment, a tip of the needle 15 and the collector 19 have a distance therebetween of about 5 cm to 50 cm. If the collector 19 is a common plate, random arranged nano lines 17 will be easily formed. If the collector 19 is parallel electrode plate, parallel arranged nano lines 17 will be formed.
In one embodiment, the syringes 11 and 13 are controlled by syringe pumps 12 and 14, respectively, to tune flow rates of the polymer solution and the metal precursor solution. For example, the polymer solution is jetted out of the needle 15 with a flow rate of about 0.1 mL/hr to 5 mL/hr, and the metal precursor solution is jetted out of the needle 15 with a flow rate of about 0.01 mL/hr to 1 mL/hr.
After the described steps, the nano lines 17 can be left at room temperature under the regular atmosphere, such that the metal compound is slowly chemically reduced by the chemically reducing agent in the metal precursor wires 17A. As a result, nano metal wires 21 are obtained. In one embodiment, the nano lines 17 can be annealed under the atmosphere to accelerate chemical reduction. For example, the anneal step can be performed at a temperature of about 100° C. to 200° C. A suitable solvent can be adopted to wash out the polymer tube 17B surrounding around the nano metal wire 21. For example, when the polymer tube 17B is PVP, it can be washed out by water, and the nano metal wires 21 in
Below, exemplary embodiments will be described in detail with reference to the accompanying drawings so as to be easily realized by a person having ordinary knowledge in the art. The inventive concept may be embodied in various forms without being limited to the exemplary embodiments set forth herein. Descriptions of well-known parts are omitted for clarity, and like reference numerals refer to like elements throughout.
In following examples, the needle had a shell pipe with a diameter of 1.25 mm and a core pipe with a diameter of 0.95 mm. The needle and the parallel electrode collector plate had a distance of 13 cm therebetween. The voltage applied to the needle was 10 kV. One electrode plate of the parallel electrode collector plate was electrically connected to ground, and another electrode plate was electrically connected to a voltage of 1 kV. Diameters of the nano lines and the nano metal wires were all measured by transmission electron microscopy (TEM, JEOL JEM-2100F).
An ethylene glycol solution of silver nitrate (30 mg/mL) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP (200 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.1 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 2.2 μm was electrostatically spun.
The nano line was annealed at 150° C. under the atmosphere for about 8 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 500 nm, a length of about 10 cm, and an aspect ratio of 200000 was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 1, the difference in Example 2 was the annealing period being changed to about 20 minutes. After annealing, the nano line was washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 500 nm, a length of about 10 cm, and an aspect ratio of 200000 was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 1, the difference in Example 3 was the annealing period being changed to about 10 hours. After annealing, the nano line was washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 500 nm, a length of about 10 cm, and an aspect ratio of 200000 was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 1, the difference in Comparative Example 1 was the nano line having a diameter of 2.2 μm being directly washed by water to remove the polymer tube (without any annealing). The silver precursor wire was measured by a spectrometer to obtain its absorption spectrum as shown in
As shown in
An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 5 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP (200 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 1 μm was electrostatically spun. The nano line was left to stand at room temperature under the atmosphere for 4 hours, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 4, the difference in Example 5 was the nano line being left to stand at room temperature under the atmosphere for 4 days. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 4, the difference in Example 6 was the nano line having a diameter of about 1 μm being annealed at 200° C. under the atmosphere for 10 minutes. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 6, the difference in Example 7 was the nano line being annealed at 200° C. for 20 minutes. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
Similar to Example 6, the difference in Example 8 was the nano line being annealed at 200° C. for 30 minutes. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in
As shown in
An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 1 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 10 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.6 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 357 nm was obtained.
An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 5 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 10 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.7 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 464 nm was obtained. As known by comparison with Example 9, a nano silver wire having a larger diameter can be obtained through a higher silver oxide concentration.
An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 1 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 30 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.4 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 285 nm was obtained. As known by comparison with Example 9, a nano silver wire having a smaller diameter can be obtained through a higher TBAP concentration.
The nano silver wire in Example 11 had a resistivity of 4.3×10−4 Ω·cm. A bulk silver had a resistivity of 1.6×10−6 Ω·cm (See Applied Physics Letters 95, 103112, 2009). A single crystalline nano silver wire had a resistivity of 2.19×10−4 Ω·cm (See Applied Physics Letters 95, 103112, 2009). A poly crystalline nano silver wire had a resistivity of 8.29×10−4 Ω·cm (See Nano letter, Vol. 2, No. 2, 2002). Accordingly, the nano silver wire prepared in Example 11 of the disclosure should be a single crystalline nano silver wire. An XRD spectrum of the nano silver wire is shown in
An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 5 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 30 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.6 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 375 nm was obtained. As known by comparison with Example 11, a nano silver wire having a larger diameter can be obtained through a higher silver oxide concentration. As known by comparison with Example 10, a nano silver wire having a smaller diameter can be obtained through a higher TBAP concentration.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed methods and materials. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102125685 | Jul 2013 | TW | national |
The present application is based on, and claims priority from Taiwan Application Serial Number 102125685, filed on Jul. 18, 2013, and claims the benefit of U.S. Provisional Application No. 61/813,445, filed on Apr. 18, 2013, the entirety of which are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61813445 | Apr 2013 | US |
