KR101800825B1 - Methods of fabricating Superionic Conductive Polymer-Silver Iodide Hybrid Nanofiber - Google Patents

Abstract

The present invention relates to a method for producing an ion-conductive polymer-silver iodide hybrid nanofiber and, more specifically, to a method for producing an ion-conductive polymer-silver iodide organic/inorganic hybrid nanofiber which ensures lightweightness as well as excellent ion-conductivity and specific surface area by dispersing and binding a silver iodide -crystal capable of being formed and maintained at room temperature in a fibrous polymeric structure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for manufacturing an ion conductive polymer-silver iodide hybrid nanofiber,

The present invention relates to a method for preparing ion-conductive polymer-silver iodide hybrid nanofibers, and more particularly, to a method for producing ion-conductive polymer-silver iodide hybrid nanofibers by dispersing and bonding? -Crystals of silver iodide capable of being formed and maintained at room temperature in a fiber polymer structure to exhibit excellent ion conductivity and specific surface area The present invention also relates to a method for producing an ion conductive polymer-iodinated organic / inorganic hybrid nanofiber exhibiting lightweight properties.

In general, the crystal structure of silver iodide is temperature-dependent. Of these,? -Crystals are known to have a high ionic conductivity similar to that of a liquid electrolyte at a high temperature of 147 ° C or higher. In the case of a solid, those having an electric conductivity in the range of 10 ^-4 to 10 ^-1 S / cm near room temperature are called super-ion conductors, and various studies have been conducted to apply such super-ion conductive crystals to a high ion conductive structure.

In order to apply high ion conductive silver iodide to an ion conductive structure, it is important to stably maintain this crystal structure, which is a high temperature crystal, near room temperature. For this purpose, there have been made examples of silver iodide compounds, There have been examples of application to electrolytes in the form of salts, which is not good.

In addition, there is an example in which silver iodide is formed in an inorganic nano-pore to form a wire-shaped silver iodide nanostructure. However, supra-ionic silver iodide has failed to form an a-crystal at room temperature (in situ x-ray diffraction study on AgI nanowire arrays, Wang, Y., Ye, C. et al., Appl Phys Lett 2003, 82, 4253.)

As a method of forming silver iodide in a polymer structure, there has been an example of producing a polymer / iodinated silver nanocomposite material by sequentially treating a polymer film with an aqueous solution of iodine / potassium iodide (I ₂ / KI) and an aqueous silver nitrate solution. However, In the process of adsorption of iodine ions, the treatment time is as long as 24 to 48 hours. In this process, due to the excessive swelling of the film, the size of the silver iodide crystals formed later increases greatly, Crystal structure of a polyamide / silver iodide nanocomposite, Fujimori, Y., Gotoh, Y. et al. J Appl Polym Sci 2008, 108, 2814.).

In addition, when poly-N-vinyl-2-pyrrolidone (PVP) -coated silver iodide nanoparticles have a particle size of about 10 nm by solution mixing and filtration under atmospheric pressure at room temperature, There have been studies to obtain ion conductivity close to liquid electrolyte at a temperature near room temperature.

However, this is a synthesis of polyvinylpyrrolidone-coated silver iodide nanoparticles, which requires post-processing such as dispersion and surface adhesion of the synthesized nanoparticles, and the need for consideration of the thermal stability of polyvinylidone in the secondary processing Problems still remain as a challenge (Size-controlled stabilization of the superionic phase in room temperature in polymer-coated AgI nanoparticles, Nature Materials 2009, 8, 476).

Therefore, in order to realize ultra-high ionic conductivity of silver iodide at room temperature, research and development for forming and maintaining? -Crystals stable at room temperature are required.

 In situ x-ray diffraction study on AgI nanowire arrays, Wang, Y., Ye, C. et al. Appl Phys Lett 2003, 82, 4253.  Conductivity and structure of a polyamide / silver iodide nanocomposite, Fujimori, Y., Gotoh, Y. et al. J Appl Polym Sci 2008, 108, 2814.  Size-controlled stabilization of the superionic phase to room temperature in polymer-coated AgI nanoparticles, Nature Materials 2009, 8, 476.

As a result of intensive studies to solve the above problems in the process for producing an ion conductive polymer-iodinated silver nanofiber of the present invention,

The silver iodide which can be formed and maintained at room temperature is stably formed at the molecular level within the fiber structure by producing the iodide-silver nanocrystal, so that the nanofiber exhibits high ion conductivity and maximizes the specific surface area, Lightweight characteristics can be exhibited, and the present invention has been completed.

Accordingly, an object of the present invention is to provide a method for producing ion-conductive polymer-iodinated organic / inorganic hybrid nanofibers that exhibits excellent ion conductivity and specific surface area as well as light weight properties.

On the other hand,

(i) dissolving a polymer in a solvent to prepare a polymer solution;

(ii) dissolving an iodine flame in a solvent to prepare an iodine solution;

(iii) mixing the polymer solution and the iodine solution to prepare a polymer / iodine complex spinning solution;

(iv) electrospinning the spinning solution to prepare a polymer / iodine composite nanofiber; And

and (v) treating the nanofibers with a silver nitrate solution to form silver iodide silver nanocrystals in the nanofibers to prepare a polymer / iodide silver hybrid nanofiber. ≪ / RTI >

In one embodiment of the present invention, the solvent is at least one selected from the group consisting of formic acid, water, methanol, ethanol, propanol, butanol, benzyl alcohol, dimethylformamide and tetrahydrofuran.

In one embodiment of the present invention, the polymer is characterized by being polyamide, polyvinyl alcohol, polyacrylonitrile or polyvinylpyrrolidone.

Here, the polyamide polymer may be polyamide 6, polyamide 66, polyamide 610, polyamide 12, polyamide 46 or polyamide 4.

In one embodiment of the present invention, the method further comprises stirring the spinning solution prepared in step (iii) before step (iv).

In one embodiment of the present invention, the concentration of the polymer solution is 0.5 to 2.5 M, the concentration of the iodine solution is 0.1 to 2.0 M, and the concentration of the spinning solution is 0.1 to 2.5 M.

The ion conductive polymer-iodinated silver hybrid nanofiber according to the present invention can exhibit high ionic conductivity, maximize specific surface area, and lightweight property due to the iodinated silver nanocrystal.

The high ion conductive hybrid nanofiber according to the present invention can exhibit flexibility and stable physical properties of the fiber polymer by stably dispersing and bonding the super-ion conductive silver iodide silver nanocrystals in the fiber polymer structure at the molecular level.

Accordingly, the nanofiber according to the present invention can be applied to a flexible battery which can be easily transformed into various shapes as a power source of a wearable electronic device, which can generate electricity in a form capable of transmitting signals by utilizing the flexibility and stability.

In addition, the nanofibers may be made of a lightweight ion conductive nanofiber nonwoven fabric having a high air content.

The method for producing an ion conductive hybrid nanofiber according to the present invention can introduce a bicomponent composite spinning technique including a modified cross section instead of a general circular cross section by designing a nozzle differently.

1 is an electron microscope (SEM) photograph of nanofibers of Examples 1 to 3 and Comparative Example 1 of the present invention.
2 is an X-ray diffraction analysis graph of the nanofiber of Example 3 and Comparative Example 1 of the present invention.
3 is a graph showing a thermogravimetric analysis of nanofibers of Example 3 and Comparative Example 1 of the present invention.
4 is a graph showing the electrical conductivities of the nanofibers of Examples 1 to 3 and Comparative Example 1 of the present invention.

Hereinafter, the present invention will be described in more detail.

A method for producing an ion conductive polymer-iodinated silver nanofiber according to an embodiment of the present invention includes:

(i) dissolving a polymer in a solvent to prepare a polymer solution;

(ii) dissolving an iodine flame in a solvent to prepare an iodine solution;

(iii) mixing the polymer solution and the iodine solution to prepare a polymer / iodine complex spinning solution;

(iv) electrospinning the spinning solution to prepare a polymer / iodine composite nanofiber; And

(v) treating the nanofibers with a silver nitrate solution to form silver iodide-silver nanocrystals in the nanofibers to prepare a polymer / iodide silver hybrid nanofiber.

According to the present invention, a polymer / iodine ion complex spinning solution can be prepared by electrospinning a polymer / iodine composite nanofiber by irradiating the polymer / iodine ion complex spinning solution with the property that polar iodide ions bind to polar polymer molecules to form a complex, And the ion conductive hybrid nanofiber can be prepared by treating the composite nanofiber with an aqueous solution of silver nitrate.

Also, the nano-sized silver iodide crystal is stably formed in the fiber polymer structure, and the phase transition temperature of the silver iodide crystal is lowered to room temperature, whereby the high ion conductive nanofiber can be produced at room temperature.

In one embodiment of the present invention, the solvent may be selected in consideration of polarity, dielectric constant, and dipole moment, and specifically, formic acid, water, methanol, ethanol, propanol, butanol, benzyl alcohol, dimethylformamide, Furan, and the like may be used, but the present invention is not limited thereto.

These solvents may be used alone or in combination.

In one embodiment of the present invention, the polymer may be a polyamide, a polyvinyl alcohol, a polyacrylonitrile, or a polyvinylpyrrolidone, It is preferable to use a polymer.

Examples of the polyamide-based polymer include polyamide 6, polyamide 66, polyamide 610, polyamide 12, polyamide 46, and polyamide 4, but the present invention is not limited thereto.

By the production method according to the present invention, it is possible to manufacture fibers of various diameters by applying to the wet spinning process by controlling the concentration of the spinning solution, and it can be made into general fibers other than the nanofiber web.

The concentration of the polymer solution is preferably 0.5 to 2.5 M, the concentration of the iodine solution is preferably 0.1 to 2.0 M, the concentration of the spinning solution is preferably 0.1 to 2.5 M, Fabrication of nanofibers by electrospinning may or may not be easy.

In one embodiment of the present invention, the method may further include stirring the spinning solution prepared in step (iii) before the step (iv).

In one embodiment of the present invention, potassium iodide (KI), sodium iodide (NaI), or the like may be used as the iodine flame, and potassium iodide is preferably used.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are for illustrative purpose only and that the scope of the present invention is not limited to these embodiments.

Example  1: ionic conductivity Polyamide 6 / Silver iodide hybrid  Manufacture of nanofibers

Example 1-1: Preparation of polyamide 6 polymer solution

A polyamide 6 polymer solution was prepared by dissolving polyamide 6 polymer (molecular weight: 35,000) in formic acid to 15 wt% (1.64M).

Example 1-2: Preparation of potassium iodide solution

Potassium iodide was dissolved in formic acid to 5 wt% (0.37M) to prepare a potassium iodide solution.

Example 1-3: Preparation of spinning solution

The polyamide 6 polymer solution prepared in Examples 1-1 and 1-2 and the potassium iodide solution were mixed at a volume ratio of 1: 1 and sufficiently stirred to prepare a polyamide 6 / potassium iodide complex spinning solution (1.0M) .

Examples 1-4: Preparation of composite nanofibers by electrospinning

The polyamide 6 / iodide composite spinning solution prepared in Example 1-3 was electrospun, then washed with water and naturally dried to prepare polyamide 6 / iodine composite nanofiber. The electrospinning conditions were 20 gauge nozzle, voltage 19 kV, extrusion speed 12 m / s, and the distance between the nozzle tip and collector was 20 m.

Example 1-5: Post-treatment process

The polyamide 6 / iodide hybrid nanofiber prepared in Example 1-4 was treated with a 10 wt% silver nitrate aqueous solution to prepare a polyamide 6 / iodide hybrid nanofiber. At this time, the treatment time was taken at the time when the color of the composite nanofiber changed to a pale yellow, specifically about 3 to 4 minutes.

Example 2: Preparation of ion conductive polyamide 6 / silver iodide hybrid nanofiber

Example 2-1: Preparation of polyamide 6 polymer solution

A polyamide 6 polymer solution was prepared in the same manner as in Example 1-1.

Example 2-2: Preparation of potassium iodide solution

Potassium iodide was dissolved in formic acid to 10 wt% (0.73M) to prepare a potassium iodide solution.

Example 2-3: Preparation of spinning solution

The polyamide 6 polymer solution prepared in Examples 2-1 and 2-2 and the potassium iodide solution were mixed at a volume ratio of 1: 1 and sufficiently stirred to prepare a polyamide 6 / potassium iodide complex spinning solution (1.18M) .

Example 2-4: Preparation of composite nanofiber by electrospinning

Electrospinning was carried out in the same manner as in Example 1-4, except that the polyamide 6 / potassium iodide solution prepared in Example 2-3 was used instead of the solution prepared in Example 1-3. To prepare a polyamide 6 / iodine composite nanofiber.

Example 2-5: Post-treatment process

The polyamide 6 / iodide hybrid nanofiber prepared in Example 2-4 was treated in the same manner as Example 1-5 to prepare a polyamide 6 / iodide hybrid nanofiber.

Example 3: Preparation of ion conductive polyamide 6 / silver iodide hybrid nanofiber

Example 3-1: Preparation of polyamide 6 polymer solution

A polyamide 6 polymer solution was prepared in the same manner as in Example 1-1.

Example 3-2: Preparation of potassium iodide solution

Potassium iodide was dissolved in 15 wt% (1.10 M) of formic acid to prepare a potassium iodide solution.

Example 3-3: Preparation of spinning solution

The polyamide 6 polymer solution prepared in Examples 3-1 and 3-2 and the potassium iodide solution were mixed at a volume ratio of 1: 1 and sufficiently stirred to prepare a polyamide 6 / potassium iodide complex spinning solution (1.37M) .

Example 3-4: Preparation of composite nanofiber by electrospinning

Electrospinning was carried out in the same manner as in Example 1-4, except that the polyamide 6 / potassium iodide solution prepared in Example 3-3 was used instead of the solution prepared in Example 1-3. To prepare a polyamide 6 / iodine composite nanofiber.

Example 3-5: Post-treatment process

The polyamide 6 / iodide hybrid nanofiber prepared in Example 3-4 was treated in the same manner as in Example 1-5 to prepare a polyamide 6 / iodide hybrid nanofiber.

Comparative Example  One: Polyamide 6  Fabrication of nanofibers, polyamide 6 / iodide complex nanofibers by potassium iodide adsorption and silver nitrate treatment

A polyamide 6 polymer solution was prepared in the same manner as in Example 1-1 and the polyamide 6 nanofiber was prepared by electrospinning the solution in the same manner as in Example 1-4 using the solution as a spinning solution. Then, the resultant was treated with an aqueous solution of potassium iodide and post-treated with an aqueous solution of silver nitrate to prepare polyamide 6 / silver iodide nanofiber.

Experimental Example 1: Evaluation of structure and physical properties of nanofiber

In order to evaluate the structure and physical properties of the nanofibers prepared in Examples 1 to 3 and Comparative Example 1, electron microscopic observation and electrical conductivity measurement were performed, and X-ray diffraction analysis and thermogravimetric analysis were performed.

Experimental example 1-1: Electron microscopic observation

The structure of the nanofibers prepared in Examples 1 to 3 and Comparative Example 1 was observed using a scanning electron microscope (SEM, HITACHI S3500N), which is shown in Fig.

Referring to FIG. 1, the diameters of the nanofibers prepared in Examples 1 to 3 and Comparative Example 1 were about 30 to 300 nm.

Experimental Example 1-2: X-ray diffraction analysis

X-ray diffraction (XRD) analysis was performed on the nanofibers prepared in Example 3 and Comparative Example 1 using a diffractometer (Rigaku, D / max-A) having Cu-k? Emission, Respectively.

Referring to FIG. 2, the diffraction peaks of the nanofibers prepared in Example 3 were confirmed by AgI crystals, but the nanofibers prepared in Comparative Example 1 showed only diffraction of polyamide 6 which was close to amorphous.

Experimental Example 1-3: Thermogravimetric analysis

In order to analyze the thermal properties of electrospun nanofibers in Example 3 and Comparative Example 1, a thermogravimetric analyzer (TGA Q 500, manufactured by Tosoh Corporation) was used, in which nitrogen gas was introduced at a rate of 100 ml / min and heated at a rate of 10 / TA Instruments), which is shown in FIG.

Referring to FIG. 3, in the result of thermogravimetric analysis (FIG. 3 (a)) of the nanofiber prepared in Comparative Example 1, loss by main chain decomposition was observed at about 417 ° C., and about 1.09% of ash remained . On the other hand, in the result of thermogravimetric analysis (FIG. 3 (b)) of the nanofibers prepared in Example 3, loss by decomposition was observed at 201, 407 and 610 ° C. Loss at 210 ℃ shows a modification of the decomposition loss of the main chain by a reduction in, 407 ℃ will due to volatilization of iodine molecule (I ₂₎ is potassium nitrate (see Formula 1) formed by the nitric acid process moves to the low temperature , And the reduction at 610 ° C was attributed to the decomposition of potassium nitrate. As a result, it was confirmed that as many as 18.6% of ash remained, and thus a large number of AgI crystals were formed in the nanofiber prepared in Example 3. [

[Chemical Formula 1]

_{^{PA6-I - + AgNO 3 -}} > PA6 + AgI + KNO 3

Experimental example 1-4: Measurement of electrical conductivity

The electrical conductivities of the nanofibers prepared in Examples 1 to 3 and Comparative Example 1 were measured using a 4-point probe (M4P302-System, Keithley Instruments Inc., USA) Device, which is shown in FIG.

In Fig. 4,? Represents the result before the nitric acid treatment and? Represents the conductivity of the nitrate-treated nanofiber (Comparative Example 1). Referring to FIG. 4, the electrical conductivity of the nanofibers prepared in Examples 1 to 3 was found to be increased as compared with that of the nanofiber prepared in Comparative Example 1. In particular, the electrical conductivity of the nanofiber prepared in Example 3 Was 2.9 × 10 ^-2 S / cm, indicating very high conductivity.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Do. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims (6)

(i) dissolving a polymer in a solvent to prepare a polymer solution;
(ii) dissolving an iodine flame in a solvent to prepare an iodine solution;
(iii) mixing the polymer solution and the iodine solution to prepare a polymer / iodine complex spinning solution;
(iv) electrospinning the spinning solution to prepare a polymer / iodine composite nanofiber; And
and (v) treating the nanofibers with a silver nitrate solution to form silver iodide silver nanocrystals in the nanofibers to prepare a polymer / iodide silver hybrid nanofiber. Way. The method according to claim 1, wherein the solvent of steps (i) and (ii) is at least one selected from the group consisting of formic acid, water, methanol, ethanol, propanol, butanol, benzyl alcohol, dimethylformamide and tetrahydrofuran Wherein the ion-conductive polymer is a silver-iodide hybrid nanofiber. The method according to claim 1, wherein the polymer is polyamide, polyvinyl alcohol, polyacrylonitrile, or polyvinylpyrrolidone. The method for producing an ion conductive polymer-iodide silver hybrid nanofiber according to claim 3, wherein the polyamide polymer is polyamide 6, polyamide 66, polyamide 610, polyamide 12, polyamide 46 or polyamide 4 . The method of manufacturing an ion conductive polymer-iodide silver hybrid nanofiber according to claim 1, further comprising stirring the spinning solution prepared in step (iii) before step (iv).
The method of claim 1, wherein the concentration of the polymer solution is 0.5 to 2.5M, the concentration of the iodine solution is 0.1 to 2.0M, and the concentration of the spinning solution is 0.1 to 2.5M. A method for producing hybrid nanofibers.

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