KR20240127251A - Nanocomposite fiber using organic silicon compounds and method for preparing the same - Google Patents

Abstract

The present invention relates to a method for producing composite nanofibers, comprising the steps of: mixing an organosilicon compound and a first organic solvent, and adding a metal compound to produce a first solution; heating the first solution to have a first viscosity to produce an electrospinning solution; electrospinning the electrospinning solution to produce a fiber precursor in the form of fibers; and heat-treating the fiber precursor at a first temperature.

Description

{NANOCOMPOSITE FIBER USING ORGANIC SILICON COMPOUNDS AND METHOD FOR PREPARING THE SAME}

The present invention relates to a composite nanofiber using an organosilicon compound and a method for producing the same, and more specifically, to a composite nanofiber including an organosilicon compound having a high degree of polymerization and various metals and a method for producing the same.

Recently, much attention has been focused on developing and applying nano-sized fibers by incorporating nanotechnology into the textile industry. One of the most notable characteristics of nanofibers is their high surface area to mass ratio. This facilitates the introduction of functional groups, ionization reactions, and particle adsorption. Through this, they are being applied in various fields such as sensors, filters, catalysts, and batteries.

Electrospinning, a method for producing nanofibers, has been studied extensively since it was known in the early 18th century that solid fibers could be created from electrically charged metals. In the late 1960s, G. I. Taylor defined the funnel shape (Taylor cone) created from a polymer melt droplet under an electric field, and completed the theoretical foundation of electrospinning. The electrospinning process is a process of applying high voltage to a polymer solution such as PVP, PAN, and PVA to produce fibers ranging from hundreds of nanometers to several micrometers in a short period of time through a jet.

The electrospinning process has been recognized as a very practical technology that can efficiently and inexpensively implement nanostructured materials. In the electrospinning process for manufacturing fibers, it is important to optimize the viscosity conditions that enable spinning. Early studies mainly focused on spinning polymer nanofibers, but as the research area of electrospinning technology has expanded from polymer nanofibers to inorganic nanofibers, it has expanded to all material fields including polymers, ceramics, and metals without any limitations on the material. Accordingly, recent studies have been conducted on methods of mixing organic polymers and inorganic materials or using fiber materials as coupling agents. Accordingly, research on nanofibers with various functions using various materials is continuously being conducted.

Prior patent: Korean registered patent 10-0871440 (2008.11.25)

The technical problem that this application seeks to solve is to provide a composite nanofiber using an organosilicon compound using a novel manufacturing method and a manufacturing method thereof.

Another technical problem that the present application seeks to solve is to provide a composite nanofiber having various functions by using an organic silsesquioxane having a high degree of polymerization and mixing it with various metals, and a method for producing the same.

The technical problems that this application seeks to solve are not limited to those described above.

To solve the above technical problems, the present invention provides a composite nanofiber and a method for manufacturing the same.

In one embodiment, the present invention provides a method for producing a composite nanofiber, including the steps of: mixing an organosilicon compound and a first organic solvent, and adding a metal compound to prepare a first solution; heating the first solution to have a first viscosity to prepare an electrospinning solution; electrospinning the electrospinning solution to produce a fiber precursor in the form of a fiber; and heat-treating the fiber precursor at a first temperature.

In one embodiment, the organosilicon compound may have a three-dimensional structure, the viscosity of the first solution may be 50 poise to 100 poise at 25° C., and the first viscosity of the electrospinning solution may be 120 poise to 180 poise at 25° C.

In one embodiment, the organosilicon compound is provided in a particle form, and the particle form may have an average particle diameter of 50 nm to 5 μm.

In one embodiment, the glass silicon compound is provided in the form of particles having a functional group on the surface, and the functional group may include at least one of a cyanide group, an amine group, a hydroxyl group, a carboxyl group, a halide group, a nitrate group, a thiocyanate group, and a thiosulfate group.

In one embodiment, the organosilicon compound is represented by the following chemical formula 1 or chemical formula 2, and may include a solid powder in the form of spherical particles or pellets of ormosil.

(Chemical formula 1) (R1SiO _3/2 )

(Chemical Formula 2) (R1SiO _3/2 )-(R2SiO _3/2 )

In the above chemical formula 1 or chemical formula 2, R1 is a substituted or unsubstituted C _5-15 aryl group, and R2 is independently selected from the group consisting of hydrogen, a substituted or unsubstituted C _1-18 alkyl group, and a substituted or unsubstituted C _5-15 aryl group.

In one embodiment, R1 may be a phenyl group, and R2 may be a substituted or unsubstituted C _1-3 alkyl group, or a substituted or unsubstituted C _5-15 aryl group.

In one embodiment, R1 is a phenyl group, R2 is a phenyl group or a substituted or unsubstituted C _1-3 alkyl group, and the molar ratio of R1:R2 can be 10:0 to 5.

In one embodiment, the first organic solvent may include at least one of tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N-methylformamide (NMF), N-methylpyrrolidone (NMP), acetone, and an amine solvent.

In one embodiment, the step of preparing the first solution further includes preparing the organosilicon compound, and the step of preparing the organosilicon compound includes adding a first base solution silane compound and stirring at a temperature of 50° C. to 80° C. and 150 rpm to 500 rpm to prepare a solid, and filtering and drying the solid, and the organosilicon compound may include at least one of phenyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, chloropropyltrimethoxysilane, 2-phenylethyltrimethoxysilane, chloropropylmethoxysilane, and 2-phenylethyltrimethoxysilane.

In one embodiment, the step of preparing the first solution further includes preparing the metal compound using a metal element, wherein preparing the metal compound comprises adding a ligand to a second base solution, stirring the solution at 40 to 60° C. for 0.5 to 3 hours, adding a metal solution in which the metal element is dissolved, stirring the solution for 0.5 to 3 hours to prepare a precipitate, filtering and washing the precipitate three or more times, and then drying the precipitate in an oven to prepare a powder form, and the metal element may be selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, Cd, and Yb.

In one embodiment, the electrospinning solution can be prepared by heating at a temperature of 50° C. to 110° C. to evaporate the solvent so that the amount of the electrospinning solution is 50 wt% to 90 wt% based on the total weight of the first solution.

In one embodiment, the electrospinning solution may be composed of a mixture of an inorganic polymer-resin type compound of ormosil represented by the following chemical formula 3 and a metal precursor.

(chemical formula 3)

(RSiO _3/2 ) + MLx

Here, R is a substituted or unsubstituted C _5-15 aryl group, M is selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, and Yb, L is selected from the group consisting of -NO ₃ , -OR (R is C _1-6 alkyl), -NR ₂ (R is C _1-6 alkyl), -COOR (R is C _1-6 alkyl), acetate, acetylacetonate, beta-ketonate, diamide, and ditholate, and x can be the number of ligands depending on the oxidation number of M.

In one embodiment, the L may be a kind of organometallic complex selected from the group consisting of -OR (R is C _1-6 alkyl), -NR ₂ (R is C _1-6 alkyl), -COOR (R is C _1-6 alkyl), acetylacetonate, beta-ketonate, diamide, and ditholate, which exhibit high solubility in an organic solvent.

In one embodiment, the organosilicon compound and the metal compound may be mixed in the electrospinning solution at a molar ratio of 1:0.1 to 1.

In one embodiment, the electrospinning is performed using a single nozzle, and the electrospinning solution can be performed under the conditions of a spinning voltage of 8-15 kV, a spinning distance of 10-30 cm, and a spinning flow rate of 1-3 mL/hr.

In one embodiment, the first temperature is less than 200° C. to 600° C., and the composite nanofibers may be in the form of an organic-inorganic hybrid including carbon.

In one embodiment, the first temperature is 600° C. to 1500° C., and the composite nanofibers may include SiO ₂ and a metal.

In one embodiment, after the step of heat-treating the fiber precursor at the first temperature, a post-treatment step is further included, wherein the post-treatment step may perform a surface treatment or an etching process on the heat-treated fiber precursor.

In one embodiment, the etching process may increase the surface area by etching the surface of the heat-treated fiber precursor using a hydrofluoric acid solution to form pores.

In one embodiment, the invention includes a composite nanofiber manufactured according to the manufacturing method described above.

In one embodiment, the composite nanofibers may have a diameter of 100 to 1000 nm.

In one embodiment, the composite nanofiber comprises one or more metal particles, the metal particles having a diameter of 5 nm to 70 nm, and the metal particles can be selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, Cd and Yb.

In one embodiment, the present invention includes a fabric or film-shaped material manufactured using the composite nanofibers.

In one embodiment, the invention includes an organic-inorganic composite resin material manufactured using the composite nanofibers and polymer resin.

According to the present invention as described above, the composite nanofibers using the organosilicon compound according to the present invention and the method for manufacturing the same are provided with a uniform diameter while having various performances by controlling various process conditions, and thus can be used as biomaterials and electronic materials.

In addition, the composite nanofiber using an organosilicon compound according to the present invention and the method for manufacturing the same use an organosilicon compound having a high degree of polymerization is manufactured to have a three-dimensional structure, thereby controlling performance so that the metal is uniformly dispersed and can be applied to various purposes.

Figure 1 is a flow chart of a method for manufacturing composite nanofibers according to an embodiment of the present invention.
Figure 2 is a drawing showing a composite nanofiber according to an embodiment of the present invention.
Figure 3 is a schematic diagram of the electrospinning device used in this example.
FIG. 4 is a schematic diagram showing a method for manufacturing composite nanofibers using organo-silsesquioxane according to another embodiment of the present invention. FIG. 5 is an image showing (a) PTMS-Ti(acac) ₂ (OiPr) ₂ , (b) PTMS-V(acac) ₃ , (c) PTMS-Cu(ND) ₂ , (d) PTMS-Ag(ND) mixed precursor solutions and (e) composite nanofibers in the form of an electrospun greedy body according to an embodiment of the present invention.
Figure 6 is an optical microscope image of a composite nanofiber according to an embodiment of the present invention.
Figure 7 shows SEM and TEM images of composite nanofibers according to an embodiment of the present invention.
FIG. 8 is a thermogravimetric curve of (a) PTMS-based green fiber and (b) PTMS-Copper ND composite green fiber according to an embodiment of the present invention.
Figure 9 shows the results of analyzing the crystal structure after heat treatment of composite nanofibers according to an embodiment of the present invention.
Figure 10 shows FT-IR spectra of SiO ₂ -TiO ₂ composite nanofibers at temperature conditions of (a) 300 ℃, (b) 500 ℃, (c) 800 ℃, and (d) 1000 ℃.
Figure 11 shows the TGA results of (a) PTMS fibers and (b) TiO ₂ -PTMS fibers.
Figure 12 shows the results of confirming the solvent resistance according to heat treatment of SiO ₂ -TiO ₂ composite nanofibers with a molar ratio of 2:1.
Figure 13 shows the results of comparing XRD of (a) SiO ₂ -TiO ₂ and (b) SiO ₂ -TiO ₂ /Ag composite nanofibers after heat treatment at 1000 ℃.
Figure 14 shows the results of analysis using TEM of SiO ₂ -TiO ₂ /Ag composite nanofibers after heat treatment at 1000 ℃.
Figure 15 shows the results of specific atomic distribution analysis of the surface of composite nanofibers for (a) Si, (b) Ti, and (c) Ag using SEM-EDX.
Figure 16 shows etching TEM images of composite nanofibers heat-treated at 1000°C (a) before etching and (b) after etching.
Figure 17 shows the UV spectrum of Rhodamine B photocatalytic degradation results for each of (a) SiO ₂ -TiO ₂ composite nanofibers, (b) SiO ₂ -TiO ₂ /Ag composite nanofibers, (c) SiO ₂ -TiO ₂ Etching composite nanofibers, and (d) SiO ₂ -TiO ₂ /Ag Etching composite nanofibers.
Figure 18 shows the results of comparing the photocatalytic decomposition rates for Rhodamine B.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. However, the technical idea of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content can be thorough and complete and so that the idea of the present invention can be sufficiently conveyed to those skilled in the art.

In this specification, when it is mentioned that a component is on another component, it means that it can be formed directly on the other component, or a third component can be interposed between them. Also, in the drawings, the thickness of films and regions is exaggerated for the effective explanation of the technical contents.

Also, although terms such as first, second, third, etc. have been used in various embodiments of this specification to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Also, "and/or" has been used herein to mean including at least one of the components listed before and after.

In the specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Also, terms such as "comprises" or "has" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, but should not be construed as excluding the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

In addition, when describing the present invention below, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Figure 1 is a flow chart of a method for manufacturing composite nanofibers according to an embodiment of the present invention. Figure 2 is a drawing showing composite nanofibers according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, an embodiment of the present invention relates to a method for manufacturing a composite nanofiber, the method including: a step of mixing an organosilicon compound and a first organic solvent, and adding a metal compound to prepare a first solution; a step of heating the first solution to have a first viscosity to prepare an electrospinning solution; a step of electrospinning the electrospinning solution to produce a fiber precursor in the form of a fiber; and a step of heat-treating the fiber precursor at a first temperature.

Typically, most research on composite nanofibers has been limited to manufacturing fibers by mixing organic polymers and inorganic raw materials or modifying existing fiber materials to use them as coupling agents. These methods have the following problems: the process steps are complicated and time-consuming, the surface of the material becomes rough when the organic polymer is removed through heat treatment, the physical shape of the fiber becomes poor, there is an uneven distribution of functional groups, a decrease in crystallinity, and it is not economical. Nevertheless, the reason why research on manufacturing fibers using pure inorganic raw materials has not been conducted is because it is difficult to manufacture a solution containing inorganic raw materials with an appropriate viscosity that allows electrospinning without using organic polymers. Therefore, a technology for manufacturing composite fibers based on inorganic polymers/resin that overcomes these problems is very important for the overall industrial sector.

On the other hand, the method for manufacturing composite nanofibers according to the present embodiment uses an inorganic polymer/resin-based organo-silsesquioxane as a precursor, so that functional organic-inorganic hybrid fiber composite nanofibers or inorganic composite nanofibers can be manufactured through an electrospinning process without using an organic polymer. In the process of manufacturing the composite nanofibers, process variables such as the concentration of the first and second solutions, the viscosity of the electrospinning solution, voltage, and release rate can be controlled to manufacture composite nanofibers having a uniform diameter. In addition, the fiber precursor in the form of a fiber manufactured through electrospinning can be made to have various chemical structures and physical properties by controlling the heat treatment temperature and process conditions. In addition, by introducing an etching process after the heat treatment, the functionality and specific surface area of the composite nanofibers could be improved.

The above organosilicon compound may be provided in a three-dimensional structure. In addition, the viscosity of the first solution may be 50 poise to 100 poise at 25° C., and the first viscosity of the electrospinning solution may be 120 poise to 180 poise at 25° C.

When the viscosity of the first solution is less than 50 poise, the organosilicon compound and the metal compound are not uniformly mixed with each other in the solution, which causes a problem, and when it exceeds 100 poise, the organosilicon compound and the metal compound are not sufficiently dissolved in the solution, which causes a problem. In addition, by maintaining the first viscosity of the electrospinning solution within the above-mentioned range, the electrospinning can be efficiently performed without problems such as nozzle clogging or electrospinning not being performed during the electrospinning process. Specifically, the first viscosity may be 50 poise to 90 poise, or 60 poise to 90 poise at 25°C, and the second viscosity may be 120 poise to 170 poise, or 120 poise to 160 poise, or 130 poise to 160 poise at 25°C.

The above organosilicon compound is provided in a particle form, and the particle form may have an average particle diameter of 50 nm to 5 μm.

The above organosilicon compound is represented by the following chemical formula 1 or chemical formula 2, and may include a solid powder in the form of spherical particles or pellets of ormosil (organically modified silicates).

(chemical formula 1)

(R1SiO _3/2 )

(chemical formula 2)

(R1SiO _3/2 )-(R2SiO _3/2 )

In the above chemical formula 1 or chemical formula 2, R1 is a substituted or unsubstituted C _5-15 aryl group, and R2 is independently selected from the group consisting of hydrogen, a substituted or unsubstituted C _1-18 alkyl group, and a substituted or unsubstituted C _5-15 aryl group.

Specifically, R1 is a phenyl group, R2 can be a substituted or unsubstituted C _1-3 alkyl group, and a substituted or unsubstituted C _5-15 aryl group, and more specifically, R1 is a phenyl group, R2 is a phenyl group or a substituted or unsubstituted C _1-3 alkyl group, and the molar ratio of R1: R2 can be 10:0 to 5. In the molar ratio of R2 to R1, when R2 exceeds 5, there is a problem that the properties of the organosilicon compound deteriorate, making it difficult to perform a subsequent process.

Specifically, when the above organosilicon compound has chemical formula 1, it can be represented by the structural formula below.

(constitutional formula)

In addition, when the organosilicon compound has chemical formula 2, (R1SiO _3/2 ) and (R2SiO _3/2 ) may be connected by a chemical bond. Specifically, the molar ratio of R1: R2 may be 10:0.01 to 5.

Alternatively, the glass silicon compound may be provided in the form of particles having a functional group on the surface. Specifically, the functional group may include at least one of a cyanogen group, an amine group, a hydroxyl group, a carboxyl group, a halide group, a nitrate group, a thiocyanate group, and a thiosulfuric acid group. The organosilicon compound may be provided with a functional group on the surface by adding a basic catalyst or an acidic catalyst to the mixture solution, and the mixture solution may be reacted while stirring at a temperature of 20° C. to 60° C. The organosilicon compound may be prepared in the form of particles having at least one of the functional groups on the surface by performing a hydrolysis reaction or a condensation polymerization reaction, etc., in the mixture solution. The organosilicon compound is provided in the form of a porous ormosil spherical particle, and the functional group may be stably provided within the pores of the organosilicon compound.

Specifically, an organosilicon compound having a functional group on the surface can be produced using the basic catalyst, and the basic catalyst can be any one selected from the group consisting of triethylamine, ammonia water, and tetramethylammonium hydroxide.

The first organic solvent may include at least one of tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N-methylformamide (NMF), N-methylpyrrolidone (NMP), acetone, and an amine solvent.

The step of preparing the first solution may further include preparing the organosilicon compound.

The step of producing the above organosilicon compound can be performed by adding a silane compound to a first base solution and stirring at 150 to 500 rpm at a temperature of 50 to 80° C. to produce a solid. The solid can be filtered and dried to produce an organosilicon compound.

The above first base solution is prepared by adding a basic substance such as anhydrous ammonia, ammonium hydroxide, or sodium hydroxide to distilled water, and the organosilicon compound may include at least one of phenyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, chloropropyltrimethoxysilane, 2-phenylethyltrimethoxysilane, chloropropylmethoxysilane, and 2-phenylethyltrimethoxysilane.

Specifically, the silane compound can be manufactured into a solid by hydrolysis and condensation reaction in the first base solution, filtering the obtained solid using a membrane filter, and washing it several times with purified water. The drying can be performed using a vacuum oven at 100° C. to 150° C. for 1 to 5 hours.

The above metal compound may be provided in the form of a compound containing a metal element. The above metal element may be selected from the group consisting of alkali and alkaline earth metals (Li, Cs, Be, Mg, Ca, Ba, Sr, etc.), main group metals (Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, etc.), and transition metals (d-group transition metals such as Ti, Zr, Cu, Ag, Cd, and f-group transition metals such as Er, Pr, Yb, etc.).

The above metal compound can be prepared using the above metal element. Specifically, a complex compound can be prepared by adding a ligand for forming a complex compound to a second base solution, stirring at 40° C. to 60° C. for 0.5 to 3 hours, and then adding a metal solution in which the metal element is dissolved therein, and stirring for 0.5 to 3 hours. The complex compound is provided in the form of a precipitate, and after filtering and washing are repeated three or more times, it can be prepared in the form of a powder by drying in an oven.

The ligand may include an organic coordination material used to prepare a metal precursor compound in the form of a complex compound that exists as a solid in an aqueous solution but is soluble in an organic solvent. Specifically, the ligand may include at least one of neodecanoic acid, a carboxylic acid having 8 to 18 carbon atoms, and an alkyl amine having 6 or more carbon atoms. More specifically, the ligand may include neodecanoic acid, and the complex compound may be a neodecanoic acid metal salt.

Specifically, the second base solution can be prepared by dissolving anhydrous ammonia, ammonium hydroxide, or sodium hydroxide in distilled water, and the metal solution can be prepared by dissolving silver nitrate in distilled water. The filtration can be performed using a membrane filter and washing three or more times with purified water, and finally washing once or more with methanol. The oven includes a vacuum oven, and drying can be performed at 28° C. to 40° C. for 10 to 24 hours.

The above electrospinning solution can be prepared by heating at a temperature of 50° C. to 110° C. to evaporate the solvent so that the amount of the electrospinning solution is 50 wt% to 90 wt% based on the total weight of the first solution. Since the electrospinning solution is provided in a range of 50 wt% to 90 wt% based on the total weight of the first solution, the subsequent electrospinning process can be easily performed, and the properties of the manufactured composite nanofibers can be efficiently maintained.

In addition, when evaporating the solvent, if the temperature is below 50°C, it is difficult to efficiently evaporate the solvent, and if it exceeds 110°C, the properties of the electrospinning solution may be altered or the viscosity may not be controlled, which may cause problems in the electrospinning process.

The above electrospinning solution may be composed of a mixture of an inorganic polymer-resin type compound of ormosil represented by the following chemical formula 3 and a metal precursor.

(chemical formula 3)

(RSiO _3/2 ) + MLx

Here, R is a substituted or unsubstituted C _6-15 aryl group, M is selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, and Yb, and L can be selected from the group consisting of -NO ₃ , -OR (R is C _1-6 alkyl), -NR ₂ (R is C _1-6 alkyl), -COOR (R is C _1-6 alkyl), acetate, acetylacetonate, beta-ketonate, diamide, and ditholate. Herein, x is the number of ligands depending on the oxidation number of M.

The above L can be selected from the group consisting of -OR (R is C _1-6 alkyl), -NR ₂ (R is C _1-6 alkyl), -COOR (R is C _1-6 alkyl), acetylacetonate, beta-ketonate, diamide, and ditholate, which show high solubility in organic solvents.

In the above electrospinning solution, the organosilicon compound and the metal compound can be mixed in a molar ratio of 1:0.1 to 1. If the molar ratio of the organosilicon compound to the metal compound is less than 0.1, the mechanical properties of the composite nanofiber may deteriorate, and if it exceeds 1, it is difficult to control the diameter of the composite nanofiber and the efficiency of the electrospinning process is reduced, which is a problem.

Figure 3 is a schematic diagram of the electrospinning device used in this example.

Referring to FIG. 3, the electrospinning is performed using a single nozzle, and the electrospinning solution can be performed under the conditions of a spinning voltage of 8-15 kV, a spinning distance of 10-30 cm, and a spinning flow rate of 1-3 mL/hr. The electrospinning solution is controlled to the first viscosity, and the spinning voltage, spinning distance, and spinning flow rate are controlled within the above-mentioned ranges to perform the electrospinning process, thereby maintaining the diameter of the composite nanofiber within a predetermined range and having uniform physical properties.

The above-mentioned electrospinning device may be composed of one or more inlets capable of injecting an electrospinning solution, a high voltage generator capable of applying an electric field, a current collector, and a syringe pump capable of discharging the electrospinning solution at a constant speed. By discharging the electrospinning solution at a constant speed using the syringe pump and applying voltage between the nozzle and the current collector, the solution can be manufactured into a fiber shape.

The method for manufacturing composite nanofibers according to the present embodiment can manufacture composite nanofibers containing one or more metals through a single nozzle. By manufacturing through a single nozzle, a post-processing process is not required, thereby improving the efficiency of the electrospinning process, and a large amount of composite nanofibers can be manufactured without differences in physical properties per batch. In addition, the composite nanofibers according to the present embodiment can easily include various metals, thereby providing composite nanofibers having various functions.

Composite nanofibers according to an embodiment of the present invention can be variously controlled within the first viscosity of the electrospinning solution used for electrospinning, so that composite nanofibers having various diameters can be easily manufactured with a uniform thickness. In addition, composite nanofibers including an organosilicon compound and a metal can be manufactured using an electrospinning process without adding an additional polymer.

In the step of heat-treating the fiber precursor at a first temperature, the form of the composite nanofiber may vary depending on the first temperature. Specifically, when the first temperature is less than 200°C to 600°C, the composite nanofiber may be in the form of an organic-inorganic hybrid including carbon. In addition, when the first temperature is 600°C to 1500°C, the composite nanofiber may be in the form of an inorganic hybrid including SiO ₂ and a metal.

When the first temperature is less than 200° C. to 600° C., the polymer constituting the composite nanofibers is not decomposed, and the composite nanofibers can be provided in the form of an organic-inorganic hybrid including a silicone polymer/resin and a metal. When the first temperature is 600° C. to 1500° C., the polymer in the organic silicon compound is decomposed and the silicon is oxidized to form SiO ₂ , and the composite nanofibers can be provided in the form of an inorganic hybrid.

The method for manufacturing a composite nanofiber according to the present embodiment may further include a post-treatment step after the step of heat-treating the fiber precursor at a first temperature.

The above post-processing step may include surface treating the heat-treated fiber precursor or performing an etching process.

According to the above post-processing step, the surface of the composite nanofiber can be controlled into various shapes, so that the composite nanofiber according to the present embodiment can be used in a wider range of fields.

The above surface treatment can be performed by impregnating the composite nanofibers with a solution containing a functional group or by using low-temperature plasma to provide the surface of the composite nanofibers with at least one functional group among a hydroxyl group (-OH), a carboxyl group (-COOH), and a peroxy acid (-COOOH).

The above etching process can increase the pores and surface area by etching the surface of the heat-treated fiber precursor using a hydrofluoric acid solution. Through the etching process, the surface of the composite nanofiber is partially dissolved, thereby increasing the surface area of the composite nanofiber and exposing it to the outside of the metal.

According to another aspect of the present invention, the present invention comprises a composite nanofiber manufactured according to the method described above.

The above composite nanofibers may have a diameter of 50 nm to 1000 nm. If the diameter of the composite nanofibers is less than 50 nm, it is difficult to uniformly fix the metal element or silicon oxide provided in the form of internal particles, and if it exceeds 1000 nm, it is difficult to efficiently perform the electrospinning process.

Additionally, the composite nanofibers include one or more metal particles, and the metal particles may have a diameter of 1 nm to 100 nm.

The above metal particles may be selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, Cd and Yb.

The present invention includes a fabric or film-shaped material manufactured using the composite nanofibers described above.

In addition, the present invention includes an organic-inorganic composite resin material manufactured using the above-described composite nanofibers and polymer resin.

FIG. 4 is a drawing schematically illustrating a method for manufacturing composite nanofibers using organo-silsesquioxane according to another embodiment of the present invention.

Referring to FIG. 4, the organosilicon compound according to the present embodiment may include organo-silsesquioxane.

After dissolving the above organic silsesquioxane in a solution, one or more metal compounds are added to prepare an electrospinning solution having a first viscosity, and the electrospinning solution can be used to prepare composite nanofibers having diameters ranging from several nanometers to micrometers through electrospinning.

The above organic silsesquioxane may be at least one of phenyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, chloropropyltrimethoxysilane, 2-phenylethyltrimethoxysilane, chloropropylmethoxysilane, and 2-phenylethyltrimethoxysilane. Specifically, the above organic silsesquioxane may be at least one of phenyltrimethoxysilane, phenylethyltrimethoxysilane, and 2-phenylethyltrimethoxysilane.

The above metal compound may include one or more, and the metal compound may include a metal element selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, Cd and Yb.

The above electrospinning solution can have a viscosity controlled from 120 poise to 180 poise at 25°C, and the electrospinning solution with controlled viscosity can be manufactured into composite nanofibers through an electrospinning device.

The above composite nanofiber is an organo-silsesquioxane hybrid material, and provides a new material that overcomes the limitations of the properties of existing organic polymer fibers by drawing out the synergistic effect of the properties of inorganic materials such as corrosion resistance, high strength, heat resistance, and chemical resistance, and organic materials such as excellent formability, hydrophobicity, and flexibility. Therefore, the functional composite nanofiber manufactured by the present invention can be applied in various ways as a biomaterial or electronic material, and can be used in a wide range of industrial fields such as catalysts, bio, and secondary batteries, for example.

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only preferred embodiments of the present invention, and the scope of the rights of the present invention is not limited by the following examples.

1. Materials

To prepare composite nanofibers, phenyltrimethoxysilane (PTMS, 97%, Alfa-Aesar), vinyltrimethoxysilane (VTMS, 97%, Alfa-Aesar), ammonium hydroxide (NH4OH, 25-28%, Daejung), acetylacetone (acacH, 97%, Alfa-Aesar), titanium isopropoxide (TTIP, 97%, Alfa-Aesar), titanium diisopropoxide bis(acetylacetonate) in 75 wt % isopropanol (Ti(acac) ₂ (OiPr) ₂ , 98%, STREM), zirconium isopropoxide (Zr(OiPr) _4, 99.8%, Sigma-Aldrich), cadmium(II) acetate (Cd(acetate) _2, 99.8%, Sigma-Aldrich), erbium nitrate (Er(NO ₃ ) _3, 99.8%, Sigma-Aldrich), triethylamine (TEA _, 99.8%, Sigma-Aldrich), silver nitrate (Ag(NO ₃ ), 99.8%, JUNSEI, neodecanoic acid (ND, 99.8%, STREM), aluminum nitrate (Al(NO ₃ ) _3, 99.8%, Sigma-Aldrich), Gallium(III) nitrate, Ga( _NO3 ) _3, 99.8%, Sigma-Aldrich), Indium(III) nitrate, In( _NO3 ) _3, 99.8%, Sigma-Aldrich, Zirconium(IV) isopropoxide, Zr(OPr) _4, 99.8%, Sigma-Aldrich, Cadmium nitrate, Cd( _NO3 ) _2, 99.8%, Sigma-Aldrich, Lithium nitrate, Li( _NO3 ) _, 99.8%, Sigma-Aldrich, Praseodymium(III) nitrate, Pr( _NO3 ) _3, Erbium(III) nitrate (Er( _NO3 ) _3, 99.8%, Sigma-Aldrich), copper(II) nitrate (Cu( _NO3 ) _2, 99.8%, Sigma-Aldrich), ethyl acetoacetic acid (99.8%, Sigma-Aldrich), praseodymium nitrate (praseodymium nitrate _, 99.8% _, Sigma-Aldrich), copper(II) nitrate (Cu( _NO3 ) _2, 99.8%, Sigma-Aldrich), N,N-Dimethylformamide anhydrous (DMF, 99.8%, Sigma-Aldrich) were purchased and used without purification.

2. Analysis method

Using a Simultaneous Thermal Analyzer (STA, STA 449 F3 Jupiter, NETZSCH), thermal characteristics of temperature change and weight change were measured simultaneously in a single analysis. The measurement conditions were a heating rate of 10 ℃/min in air, and the temperature corresponding to the decomposition of metal compounds and organic groups, their respective contents in the fiber, and changes in the material properties of the fiber according to temperature were analyzed.

To confirm the change in the chemical structure of the fiber depending on the manufactured fiber and heat treatment temperature, Fourier transform infrared spectroscopy (FT-IR, AAB FTLA2000) was used for analysis.

To investigate the physical flexibility of the fibers, solvent resistance, and dispersion morphology of the precursors, a drop of the sample of the fibers dispersed in ethanol was applied to a carbon-coated copper grid and analyzed by scanning electron microscopy (EF-TEM, JEM-2000EXLL JEOL).

The crystal phases of TiO ₂ nanoparticles and Ag metal were characterized by X-ray powder diffraction (XRD) patterns using a Rigaku D/RAD-C diffractometer with Cu-Kα radiation (λ = 1.5418 nm) at 40 kV and 100 mA.

The change in the crystallinity of each metal according to the heat treatment temperature was confirmed. Since the difference in the distribution of each metal corresponding to TiO ₂ and Ag on the surface of the nanofibers could not be known, the distribution corresponding to each TiO ₂ and Ag according to the color was confirmed using a scanning electron microscope (FE-SEM-EDX, Verios G4UC).

3. Manufacturing of nanofibers

Manufacturing Example 1 (PTMS-based organic silsesquinoxane particles)

A 250-ml three-necked flask was filled with 100 ml of purified water and _NH4OH (0.1 ml, 2.9 mmol), the temperature was adjusted to 70 ℃, and the mixture was stirred at 350 rpm. After 10 minutes, 14.36 ml of PTMS (phenyltrimethoxysilane) (0.0775 mol) was added to the solution using a syringe and reacted for 3 hours. PTMS particles were formed by hydrolysis and condensation reactions. The obtained PTMS particles after 3 hours were filtered using a membrane filter and washed several times with purified water. 9.98 g of PTMS particles were prepared by drying in a vacuum oven at 110 ℃ for 2 hours, and the results are shown in Table 1. The PTMS particles were obtained in a yield of 99.8%.

Manufacturing Example 2 (PTMS/VTMS-based composite organic silsesquinoxane particles)

A 250-ml three-necked flask was charged with 100 ml of purified water, 10 ml of methyl alcohol, and 10 ml of _NH4OH , the temperature was adjusted to 60 ℃, and the mixture was stirred at 450 rpm. After 1 minute, 5.4 ml of PTMS (0.0289 mol) was added to the solution using a syringe, and the mixture was reacted for 1.5 hours. After that, 0.6 ml of VTMS (Vinyltrimethoxysilane) (0.0029 mmol) was additionally added using a syringe, and the mixture was stirred for an additional 1.5 hours. PTMS-VTMS-based composite component particles having a ratio of 9:1 were formed by hydrolysis and condensation reactions. After 3 hours, the obtained composite particles were filtered using a membrane filter and washed several times with purified water. 9.8 g of PTMS-VTMS composite particles were prepared by drying in a vacuum oven at 110 ℃ for 2 hours, and the results are shown in Table 1. The yield of composite particles was obtained as 99.2%.

Manufacturing Examples 3 to 5 (Ti precursor, Zr precursor, Cd precursor)

Titanium(IV) diisopropoxide bis(acetylacetonate) (Ti(acac) ₂ (OiPr) ₂ ) was prepared as a Ti precursor by the following method. 4.4 g (11.5 mmol) of titanium isopropoxide (TTIP) was added to 3.1 g (23.0 mmol) of acetylacetone (acacH), and the mixture was stirred at 300 rpm for 30 minutes to synthesize Ti(acac) ₂ (OiPr) ₂ .

In addition, zirconium diisopropoxide bis(acetylacetonate) (Zirconium(IV) diisopropoxide bis(acetylacetonate), Zr(acac) ₂ (OiPr) ₂ ) was prepared as a Zr precursor and cadmium acetylacetonate (Cd(acac) ₂ ) was prepared as a Cd precursor, respectively. The Zr and Cd precursors were prepared in the same manner as the Ti precursor described above, except that zirconium isopropoxide (Zr(OiPr) ₄ ) and cadmium acetate (Cadmium(II) acetate, Cd(acetate) ₂ ) were used as the metal raw materials, respectively, and are shown in Table 1.

Manufacturing Examples 6 to 8 (Er precursor, In precursor, V precursor)

Erbium(III) acetylacetonate (Er(acac) ₃ ) as an Er precursor was prepared by the following method. 32.6 ml of 1 M erbium nitrate (Er(NO ₃ ) ₃ ) (42.55 mmol) solution was added to 100 ml of distilled water. 12.8 g of acetylacetone (acacH) (127.8 mmole) was added, and 24.9 ml of triethylamine (TEA) (178.7 mmole) was added dropwise over 3 minutes, followed by stirring at a speed of 300 rpm to synthesize Er(acac) ₃ .

In addition, indium acetylacetonate (Indium(III) acetylacetonate, In(acac) ₃ ) as an In precursor and vanadium acetylacetonate (Vanadium(III) acetylacetonate, V(acac) ₃ ) as a V precursor were respectively manufactured. Except that indium nitrate (Indium(III) nitrate, In(NO ₃ ) ₃ ) was used as the metal raw material for the In precursor and vanadium oxynitrate (Vanadium(V) oxytrinitrate, VO(NO ₃ ) ₃ ) for the V precursor were used as the metal raw material, the manufacturing methods were the same as those for the Er precursor described above and are shown in Table 1.

division type Raw materials Manufacturing example 1 PTMS particles PTMS Manufacturing example 2 PTMS/VTMS particles PTMS, VTMS Manufacturing example 3 Ti precursor (Ti(acac)2(OiPr) ₂ ) TTIP Manufacturing example 4 Zr precursor (Zr(acac)2(OiPr) ₂ ) Zr(OiPr) ₄ Manufacturing example 5 Cd precursor (Cd(acac) ₂ ) Cd(acetate) ₂ Manufacturing example 6 Er precursor (Er(acac) ₃ ) Er(NO ₃ ) ₃ Manufacturing example 7 In precursor (In(acac) ₃ ) In(NO ₃ ) ₃ Manufacturing example 8 V precursor (V(acac) ₃ ) V(NO ₃ ) ₃

Manufacturing Examples 9 to 18 (Ag precursor, Al precursor, Ga precursor, In precursor, Zr precursor, Cd precursor, Li precursor, Pr precursor, Er precursor, Cu precursor)

0.7 g of sodium hydroxide (0.0179 mol) was dissolved in 50 ml of distilled water, 3.08 g of neodecanoic acid (0.0179 mol) was added, the temperature was adjusted to 50 ℃, and the mixture was stirred for 1 hour. Here, a solution of 3.04 g of silver nitrate (Ag( _NO3 ) (0.0179 mol) dissolved in 50 ml of distilled water was added and stirred for 1 hour. A white precipitate of silver neodecanoate (Ag(ND)) was generated, which was filtered using a membrane filter, washed with purified water at least three times, and finally washed once with methanol. It was dried in a vacuum oven at 30°C for 12 hours. 4.44 g of silver neodecanoate (Ag(ND)) powder (yield 88.8%) was obtained.

Also, aluminum nitrate (Al( _NO3 ) ₃ ), gallium nitrate (Gallium(III) nitrate) (Ga( _NO3 ) ₃ ), indium nitrate (In( _NO3 ) ₃ ), zirconium(IV) isopropoxide (Zr(OPr) ₄ ), cadmium nitrate (Cd( _NO3 ) ₂ ), lithium nitrate (Li( _NO3 )), praseodymium nitrate (Pr( _NO3 ) ₃ ), erbium nitrate (Er( _NO3 ) ₃ ), copper nitrate (Copper(II) nitrate) (Cu( _NO3 ) ₂ ) was used as a metal raw material in the same manner as the Ag precursor described above, except that the Al precursor (Al(ND) ₃ ), Ga precursor (Ga(ND) ₃ ), In precursor (In(ND) ₃ ), Zr precursor (Zr(ND) ₄ ), Cd precursor (Cd(ND) ₂ ), Li precursor (LiND), Pr precursor (Pr(ND) ₃ ), Er precursor (Er(ND) ₃ ), and Cu precursor (Cu(ND) ₂ ) were manufactured, respectively, and are shown in Table 2.

division type Raw materials Manufacturing example 9 Ag precursor (Ag(ND)) Ag(NO ₃ ) Manufacturing example 10 Al precursor (Al(ND)3) Al(NO ₃ ) ₃ Manufacturing example 11 Ga precursor (Ga(ND) ₃ ) Ga(NO ₃ ) ₃ Manufacturing example 12 In precursor (In(ND) ₃ ) In(NO ₃ ) ₃ Manufacturing example 13 Zr precursor (Zr(ND) ₄ ) Zr(OPr) ₄ Manufacturing example 14 Cd precursor (Cd(ND) ₂ ) Cd(NO ₃ ) ₂ Manufacturing example 15 Li precursor (LiND) Li(NO ₃ ) Manufacturing example 16 Pr precursor (Pr(ND) ₃ ) Pr(NO ₃ ) ₃ Manufacturing example 17 Er precursor (Er(ND) ₃ ) Er(NO ₃ ) ₃ Manufacturing example 18 Cu precursor (Cu(ND) ₂ ) Cu(NO ₃ ) ₂

Manufacturing Examples 19 and 20 (Pr-EAA precursor, Cu-EAA precursor)

0.7 g of sodium hydroxide (0.017 9 mol) was dissolved in 50 ml of distilled water, 3.08 g of ethyl acetoacetic acid (130.14, 1.02 g/ml 0.0179 mol) was added, the temperature was adjusted to 50 ℃, and the mixture was stirred for 1 hour. To this, a solution of 3.04 g of praseodymium nitrate (326.92, 0.0179 mol) dissolved in 50 ml of distilled water was added, and the mixture was stirred for 1 hour. Praseodymium ethyl acetoacetate (Pr(EAA) ₃ ) (Pr-EAA precursor) as a white precipitate was generated, filtered using a membrane filter, washed with purified water three times or more, and finally washed once with methanol. It was dried in a vacuum oven at 30 ℃ for 12 hours. 4.44 g of praseodymium neodecanoate (Pr-EAA precursor) powder (yield 88.8%) was obtained.

In addition, copper(II) ethyl acetoacetate (Cu(EAA) ₂ ) was prepared as a Cu-EAA precursor. The Cu-EAA precursor was prepared in the same manner as the Pr-EAA precursor described above, except that copper(II) nitrate (Cu(NO ₃ ) ₂ ) was used as the metal raw material, and is shown in Table 3.

division type Raw materials Manufacturing example 19 Pr-EAA precursor (Pr(EAA) ₃ ) Pr(NO ₃ ) ₃ Manufacturing example 20 Cu-EAA precursor (Cu(EAA) ₂ ) Cu(NO ₃ ) ₂

Experimental examples 1 to 8 (Preparation of precursor solution for electrospinning using organic silsesquioxane particles)

The PTMS-based organic silsesquioxane particles (hereinafter, PTMS particles) or (PTMS/VTMS-based composite organic silsesquioxane particles (hereinafter, PTMS/VTMS particles) manufactured in Manufacturing Example 1 or Manufacturing Example 2 were each dissolved in anhydrous DMF to prepare an electrospinning solution. The amount of the PTMS particles or PTMS/VTMS particles was fixed to 3 g, and the amount of the solvent was adjusted so that the solid contents were 68, 70, 72, and 74 wt%, respectively, and the particles were dissolved by stirring at a speed of 150 rpm at 50 °C for 3 hours to prepare a precursor solution for spinning, which is shown in Table 4. Table 4 shows electrospinning solutions manufactured with different solid contents.

division Particle type Particle content menstruum Solids content Experimental Example 1 PTMS particles 3g Anhydrous DMF 68wt% Experimental example 2 PTMS particles 3g Anhydrous DMF 70wt% Experimental Example 3 PTMS particles 3g Anhydrous DMF 72wt% Experimental example 4 PTMS particles 3g Anhydrous DMF 74wt% Experimental Example 5 PTMS/VTMS particles 3g Anhydrous DMF 68wt% Experimental example 6 PTMS/VTMS particles 3g Anhydrous DMF 70wt% Experimental example 7 PTMS/VTMS particles 3g Anhydrous DMF 72wt% Experimental Example 8 PTMS/VTMS particles 3g Anhydrous DMF 74wt%

Experimental examples 9 to 12 (Preparation of precursor solution for electrospinning using PTMS particles and Ti precursor)

3 g of PTMS particles manufactured according to Manufacturing Example 1 were dissolved in anhydrous DMF, and then Ti(acac) ₂ (OiPr) ₂ as a Ti precursor was added to the solution at a molar ratio of 2:1 to prepare a solution. In order to control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100 °C to prepare an electrospinning solution having an appropriate viscosity. At this time, the viscosity was approximately 140 poise.

In addition, after dissolving the manufactured PTMS particles in anhydrous DMF, Ti(acac) ₂ (OiPr) ₂ as a Ti precursor was added to the solution at molar ratios of 4:1, 3:1, and 1.5:1, and inorganic composite fiber precursor solutions having different ratios were manufactured using the same method as described above, and the results are shown in Table 5.

division Particle type Particle content Metal precursor PTMS:Ti molar ratio menstruum viscosity Experimental Example 9 PTMS particles 3g Ti precursor 2:1 Anhydrous DMF 140 poise Experimental Example 10 PTMS particles 3g Ti precursor 4:1 Anhydrous DMF 140 poise Experimental Example 11 PTMS particles 3g Ti precursor 3:1 Anhydrous DMF 140 poise Experimental Example 12 PTMS particles 3g Ti precursor 1.5:1 Anhydrous DMF 140 poise

Experimental examples 13 to 16 (Preparation of precursor solution for electrospinning using PTMS particles and Er precursor)

3 g of PTMS particles manufactured according to Manufacturing Example 1 were dissolved in anhydrous DMF, and then Er(acac) ₃ as an Er precursor was added to the solution at a molar ratio of 2:1 to prepare a solution. In order to control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100 °C to prepare an electrospinning solution having an appropriate viscosity. At this time, the viscosity was approximately 140 poise.

In addition, after dissolving the manufactured PTMS particles in anhydrous DMF, Er(acac) ₃ as an Er precursor was added to the solution at molar ratios of 4:1, 3:1, and 1.5:1, and inorganic composite fiber precursor solutions having different ratios were manufactured using the same method as described above, and the results are shown in Table 6.

division Particle type Particle content Metal precursor PTMS:Er mol ratio menstruum viscosity Experimental Example 13 PTMS particles 3g Er precursor 2:1 Anhydrous DMF 140 poise Experimental Example 14 PTMS particles 3g Er precursor 4:1 Anhydrous DMF 140 poise Experimental Example 15 PTMS particles 3g Er precursor 3:1 Anhydrous DMF 140 poise Experimental Example 16 PTMS particles 3g Er precursor 1.5:1 Anhydrous DMF 140 poise

Experimental examples 17 to 20 (Preparation of precursor solution for electrospinning using PTMS particles and Ag precursor)

3 g of PTMS particles manufactured according to Manufacturing Example 1 were dissolved in anhydrous DMF, and Ag(ND) as an Ag precursor was added to the solution at a molar ratio of 2:1 to prepare a solution. In order to control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100°C to prepare an electrospinning solution having an appropriate viscosity. At this time, the viscosity was approximately 140 poise.

In addition, after dissolving the manufactured PTMS particles in anhydrous DMF, Ag(ND) as an Ag precursor was added to the solution at molar ratios of 4:1, 3:1, and 1.5:1, and inorganic composite fiber precursor solutions having different ratios were manufactured using the same method as described above, and are shown in Table 7.

division Particle type Particle content Metal precursor PTMS:Ag molar ratio menstruum viscosity Experimental Example 17 PTMS particles 3g Ag precursor 2:1 Anhydrous DMF 140 poise Experimental Example 18 PTMS particles 3g Ag precursor 4:1 Anhydrous DMF 140 poise Experimental Example 19 PTMS particles 3g Ag precursor 3:1 Anhydrous DMF 140 poise Experimental Example 20 PTMS particles 3g Ag precursor 1.5:1 Anhydrous DMF 140 poise

Experimental examples 21 to 24 (Preparation of precursor solution for electrospinning using PTMS particles and Pr-EAA precursor)

3 g of PTMS particles manufactured according to Manufacturing Example 1 were dissolved in anhydrous DMF, and then Pr(EAA) ₃ as a Pr-EAA precursor was added to the solution at a molar ratio of 2:1 to prepare a solution. In order to control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100°C to prepare an electrospinning solution having an appropriate viscosity. At this time, the viscosity was approximately 140 poise.

In addition, after dissolving the manufactured PTMS particles in anhydrous DMF, Pr(EAA) ₃ as a Pr-EAA precursor was added to the solution at molar ratios of 4:1, 3:1, and 1.5:1 to manufacture inorganic composite fiber precursor solutions at different ratios, which are shown in Table 8.

division Particle type Particle content Metal precursor PTMS:EAA molar ratio menstruum viscosity Experimental Example 21 PTMS particles 3g Pr-EAA precursor 2:1 Anhydrous DMF 140 poise Experimental Example 22 PTMS particles 3g Pr-EAA precursor 4:1 Anhydrous DMF 140 poise Experimental Example 23 PTMS particles 3g Pr-EAA precursor 3:1 Anhydrous DMF 140 poise Experimental example 24 PTMS particles 3g Pr-EAA precursor 1.5:1 Anhydrous DMF 140 poise

Experimental examples 25 to 28 (Preparation of precursor solution for electrospinning using PTMS particles and Ti precursor, Ag precursor)

According to Manufacturing Example 1, 3 g of PTMS particles were dissolved in anhydrous DMF, and then Ti(acac) ₂ (OiPr) ₂ as a Ti precursor was added to the solution at a molar ratio of 2:1 to prepare a mixed solution. A solution was prepared by adding Ag precursor (Ag(ND)) to the solution containing Ti at a molar ratio of Ti to Ag of 1:1. In order to control the viscosity, the solution was stirred at 240 rpm at 100 °C for 1 hour to prepare an electrospinning solution having an appropriate viscosity. At this time, the viscosity was about 140 poise.

In addition, after dissolving the manufactured PTMS particles in anhydrous DMF, the molar ratios of Ti precursor and Ag precursor were added to the solution at molar ratios of 2:1, 1.5:1, and 0.5:1, thereby manufacturing inorganic composite fiber precursor solutions containing different ratios of metal precursors, which are shown in Table 9.

division Particle type Particle content Metal precursor PTMS:Ti molar ratio Ti:Ag molar ratio menstruum viscosity Experimental example 25 PTMS particles 3g Ti precursor, Ag precursor 2:1 1:1 Anhydrous DMF 140 poise Experimental example 26 PTMS particles 3g Ti precursor, Ag precursor 2:1 2:1 Anhydrous DMF 140 poise Experimental example 27 PTMS particles 3g Ti precursor, Ag precursor 2:1 1.5:1 Anhydrous DMF 140 poise Experimental Example 28 PTMS particles 3g Ti precursor, Ag precursor 2:1 0.5:1 Anhydrous DMF 140 poise

Experimental Example 29 (Preparation of Precursor Solution for Electrospinning Using PTMS Particles, Ag Precursor, and Cu Precursor)

According to Manufacturing Example 1, 3 g of PTMS particles were dissolved in anhydrous DMF, and Ag(ND) was added as an Ag precursor to the solution to prepare a solution. A Cu precursor (Cu(ND) ₂ ) was added to the solution containing Ag, and the molar ratio of PTMS:Ag:Cu was 3:0.5:0.5. In order to control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100 °C to prepare an electrospinning solution having an appropriate viscosity, which is shown in Table 10. At this time, the viscosity was about 140 poise.

division Particle type Particle content Metal precursor PTMS:Ag:Cu molar ratio menstruum viscosity Experimental example 25 PTMS particles 3g Ag precursor, Cu precursor 3:0.5:0.5 Anhydrous DMF 140 poise

Experimental examples 30 to 47 (Preparation of precursor solutions for electrospinning using PTMS particles and various metal precursors)

3 g of PTMS particles manufactured according to Manufacturing Example 1 were dissolved in anhydrous DMF, and then a Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) was added to the solution at a molar ratio of 2:1 to prepare a solution. In order to control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100 °C to prepare an electrospinning solution having an appropriate viscosity. At this time, the viscosity was approximately 140 poise.

In addition, after dissolving the manufactured PTMS particles in anhydrous DMF, instead of the Ti precursor, the metal precursors listed in Table 11 were added to the solution using the same method and molar ratio, and inorganic composite fiber precursor solutions containing different types of metal precursors were manufactured.

division Particle type Particle content Metal precursor PTMS:Metal Molar Ratio menstruum viscosity Experimental example 30 PTMS particles 3g Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) 2:1 Anhydrous DMF 140 poise Experimental Example 31 PTMS particles 3g Zr precursor (Zr(acac) ₂ (OiPr) ₂ ) 2:1 Anhydrous DMF 140 poise Experimental example 32 PTMS particles 3g Cd precursor (Cd(acac) ₂ ) 2:1 Anhydrous DMF 140 poise Experimental example 33 PTMS particles 3g Er precursor (Er(acac) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental example 34 PTMS particles 3g In precursor (In(acac) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental example 35 PTMS particles 3g V precursor (V(acac) ₃₎ 2:1 Anhydrous DMF 140 poise Experimental example 36 PTMS particles 3g Ag precursor (Ag(ND)) 2:1 Anhydrous DMF 140 poise Experimental example 37 PTMS particles 3g Al precursor (Al(ND) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental example 38 PTMS particles 3g Ga precursor (Ga(ND) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental example 39 PTMS particles 3g In precursor (In(ND) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental Example 40 PTMS particles 3g Zr precursor (Zr(ND) ₄ ) 2:1 Anhydrous DMF 140 poise Experimental Example 41 PTMS particles 3g Cd precursor (Cd(ND) ₂ ) 2:1 Anhydrous DMF 140 poise Experimental example 42 PTMS particles 3g Li precursor (LiND) 2:1 Anhydrous DMF 140 poise Experimental example 43 PTMS particles 3g Pr precursor (Pr(ND) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental Example 44 PTMS particles 3g Er precursor (Er(ND) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental example 45 PTMS particles 3g Cu precursor (Cu(ND) ₂ ) 2:1 Anhydrous DMF 140 poise Experimental example 46 PTMS particles 3g Pr-EAA precursor (Pr(EAA) ₃ ) 2:1 Anhydrous DMF 140 poise Experimental Example 47 PTMS particles 3g Cu-EAA precursor (Cu(EAA) ₂ ) 2:1 Anhydrous DMF 140 poise

Experimental examples 48 to 51 (Preparation of precursor solution for electrospinning according to viscosity using PTMS particles and Ti precursor)

3 g of PTMS particles manufactured according to Manufacturing Example 1 were dissolved in anhydrous DMF, and then a Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) was added to the solution at a molar ratio of 2:1 to prepare a solution. To control the viscosity, the solution was stirred at 240 rpm for 1 hour at 100 °C. At this time, the viscosity was varied by controlling the amount of solvent evaporation as described in Table 12 to prepare an electrospinning solution.

division Particle type Particle content Metal precursor Molar ratio of metal precursor to particle menstruum viscosity Experimental Example 48 PTMS particles 3g Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) 2:1 Anhydrous DMF 100 poise Experimental Example 49 PTMS particles 3g Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) 2:1 Anhydrous DMF 120 poise Experimental Example 50 PTMS particles 3g Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) 2:1 Anhydrous DMF 180 poise Experimental Example 51 PTMS particles 3g Ti precursor (Ti(acac) ₂ (OiPr) ₂ ) 2:1 Anhydrous DMF 200 poise

Manufacturing of composite inorganic fibers using electrospinning

The electrospinning device used in this experiment was a lab-type horizontal electrospinning device (NNC-ESP200) and components of the spinning device, including a syringe pump, a high-voltage power supply (NNC-HV60), a collector (78-1200, KDS-200, 206395), and a nozzle, sold by Nano NC, a venture company specializing in manufacturing and selling electrospinning devices for producing nanofibers and electrospray devices capable of producing nano- to micro-particles. The electrospinning device consists of a syringe pump (KDS-200) that supplies the solution, a high-voltage power supply (Power supply) that supplies voltage, and a collector where the fibers are collected. One of the precursor solutions manufactured in the experimental example described above is injected into a 10 ml syringe and then mounted on the syringe pump. A 21G (0.49 mm) syringe tip was used, and the solution was supplied by adjusting the solution discharge speed through the pump to 1 ml/hr. The voltage to the syringe tip was adjusted within the range of 8 kV and supplied, and the distance between the syringe and the tip (TCD, Tip to Collector Distance) was adjusted to 15 cm. The collector used a flat plate wrapped with aluminum foil to capture fibers. The solution formed at the tip of the syringe tip forms a jet by receiving voltage, and fibers are obtained at the collector.

Preparation of organic-inorganic hybrid fibers and composite inorganic fibers by heat treatment of electrospun inorganic composite fibers

Inorganic fibers manufactured using electrospinning were heat-treated at temperatures of 300 ℃, 500 ℃, 800 ℃, and 1000 ℃ in an air atmosphere. The heat treatment was performed by heating to the corresponding temperature at a heating rate of 10 ℃/min, maintaining the temperature for one hour, and then cooling to room temperature. After the heat treatment, the solvent resistance of the heat-treated fibers was confirmed by putting them in solvents such as ethanol, acetone, and DMF.

Surface etching (dissolution) process of organic-inorganic hybrid fibers and inorganic composite fibers

In order to increase the specific surface area and pores of heat-treated organic-inorganic hybrid fibers and inorganic composite fibers and to expose the metal distributed inside the fibers to the outside to increase the functionality and increase the surface area, the surface of the fibers was partially dissolved. To this end, 1 g of heat-treated SiO ₂ -TiO ₂ fibers were immersed in a solution prepared by adding 0.1 ml HF (50% aqueous solution) to 9 mL of purified water to make a 0.5 M solution and maintained for 10 minutes. In addition, the degree of surface dissolution was controlled by changing the immersion time in the acid solution to 20 and 30 minutes.

The photocatalytic properties of titania composite fibers were investigated according to the presence or absence of Ag. 0.01 g of fibers were placed in 30 ml (1 x 10 ^-5 M) of Rhodamine B organic dye aqueous solution, wrapped with aluminum foil to block light, and stirred for about 15 minutes to disperse them. A UV light source (light source in the range of 300-420 nm, maximum intensity 7.6 mW/cm ² at 365 nm, Raynics co.) was used. The concentration of Rhodamine B was measured by taking it out of the vial at time intervals of 30, 60, 90, 120, 150, and 180 min, extracting about 3 ml of the solution with a syringe, and measuring the absorbance. In the case of the photocatalytic experiment for etching, the same content was used based on the TiO ₂ in the fiber.

4. Evaluation and Results

FIG. 5 is an image showing (a) PTMS-Ti(acac) ₂ (OiPr) ₂ , (b) PTMS-V(acac) ₃ , (c) PTMS-Cu(ND) ₂ , (d) PTMS-Ag(ND) mixed precursor solutions and (e) electrospun greedy body-shaped composite nanofibers according to an embodiment of the present invention. FIG. 6 is an optical microscope image of composite nanofibers according to an embodiment of the present invention. FIG. 7 is SEM and TEM images of composite nanofibers according to an embodiment of the present invention.

In Fig. 5, (a) shows photographs of the precursor solutions for electrospinning of Experimental Example 9, (b) shows photographs of Experimental Example 35, (c) shows photographs of Experimental Example 45, and (d) shows photographs of Experimental Example 36. Fig. 5 (e) and Figs. 6 and 7 show photographs of composite nanofibers manufactured by performing electrospinning using the precursor for electrospinning of Experimental Example 9. When performing electrospinning, spinning was performed by fixing the process variables at an injection rate of 1 ml/hr, a voltage of 8 kV, and a TCD of 15 cm.

Referring to FIGS. 5 to 7, it was confirmed that no solid material was visible in the manufactured precursor solution for electrospinning, and that both PTMS particles and metal precursors were uniformly dissolved. When electrospinning was performed with the manufactured precursor solution for electrospinning, no problems such as nozzle clogging occurred, and fibers with a uniform thickness of approximately 500 nm were manufactured without breaking in the middle, confirming that mass production was possible.

Figure 8 shows thermogravimetric curves of (a) PTMS-based green fiber and (b) PTMS and Cu(ND) ₂ composite nanofibers according to an embodiment of the present invention.

Fig. 8 (a) shows a composite nanofiber manufactured using Experimental Example 1, and (b) shows a composite nanofiber manufactured according to Experimental Example 45. Referring to Fig. 8, it was confirmed that, unlike the composite nanofiber using only PTMS, the thermogravimetric curve appeared step by step in the case of the composite nanofiber containing more copper.

Figure 9 shows the results of analyzing the crystal structure after heat treatment of composite nanofibers according to an embodiment of the present invention.

Fig. 9 shows the results of fabricating composite nanofibers by electrospinning using an electrospinning precursor solution, heat-treating the fabricated composite nanofibers at 800°C for 1 hour, and confirming the crystal structure. In Fig. 9, (a) shows the results for Experimental Example 17, (b) shows the results for Experimental Example 25, (c) shows the results for Experimental Example 43, and (d) shows the results for Experimental Example 44. Referring to Fig. 9, it was confirmed that the composite nanofibers fabricated using each electrospinning precursor solution maintained the metal included in the electrospinning precursor solution even after the heat treatment. In addition, in the case of some metal precursors, it was confirmed that the metal included in the metal precursor appeared in the form of metal oxide after the heat treatment.

Referring to Experimental Examples 9 to 12, Ti(acac) ₂ (OiPr) ₂ as a Ti precursor was added to the PTMS solution in which PTMS particles were dissolved to prepare precursor solutions for electrospinning at various molar ratios (4:1, 2:1, 1.5:1, 1:1). When electrospinning was performed, the process variables were fixed to an injection rate of 1 ml/hr, a voltage of 8 kV, and a TCD of 15 cm, and spinning was performed. When the molar ratio was less than 4:1, the titania content was low, and the titania crystallinity could not be confirmed after heat treatment. On the other hand, when the molar ratio was 1.5:1, electrospinning was possible, but the PTMS fibers were partially melted, making it difficult to maintain the shape of the fibers. It was confirmed that electrospinning was not possible when the molar ratio was 1:1. That is, when a metal precursor having the same molar ratio as that of silica was mixed, fibers could not be obtained by electrospinning.

Electrospun inorganic composite fibers obtained using a 2:1 molar ratio electrospinning precursor solution sample according to Experimental Example 9 were dried in a vacuum oven at 80 ℃ for 1 hour and then heated at temperatures of 300 ℃, 500 ℃, 800 ℃, and 1000 ℃ at a heating rate of 10 ℃/min. Then, the temperature was maintained for 1 hour and heat-treated. The before and after heat treatment were visually compared. The composite nanofibers immediately after fabrication before heat treatment and the composite nanofibers after drying at 80 ℃ exhibited a light yellow color due to the mixed use of Ti(acac) ₂ (OiPr) ₂ reagent as a Ti precursor. On the other hand, composite nanofibers exhibited colors of dark yellow, ivory, and white above 300 ℃, 500 ℃, and 800 ℃, respectively.

Figure 10 shows FT-IR spectra of SiO ₂ -TiO ₂ composite nanofibers at temperature conditions of (a) 300 ℃, (b) 500 ℃, (c) 800 ℃, and (d) 1000 ℃.

Referring to Fig. 10, the chemical changes in the inorganic composite fiber of Experimental Example 9 having a molar ratio of 2:1 were confirmed according to the heat treatment temperature conditions of 300 ℃, 500 ℃, 800 ℃, and 1000 ℃ using FT-IR analysis.

At a temperature of 300 ℃, the CH peaks appearing in the phenyl group were 2915 cm ^-1 , 2848 cm ^-1 , the C = C peak was 1432 cm ^-1 , the C - C peak was 739 cm ^-1 , 682 cm ^-1 , the peaks of Si-O-Si were 1136 cm ^-1 , 1030 cm ^-1 , the peaks of C = O were 1595 cm ^-1 , 1644 cm ^-1 , the peak of Ti-O-Si was 948 cm ^-1 , and the CH peak corresponding to iso-propoxide was confirmed at 1429 cm ^-1 . At a temperature of 500 ℃, the peaks corresponding to the phenyl group were thermally decomposed and disappeared. At temperatures above 1000 ℃, the peak of Ti-O-Ti appeared at 652 cm ^-1 , and it was confirmed that the Ti-O-Si peak decreased in contrast to the growth of the Ti-O-Ti peak.

Figure 11 shows the TGA results of (a) PTMS fibers and (b) TiO ₂ -PTMS fibers. In Figure 11, (a) Experimental Example 1 and (b) Experimental Example 9 were used as precursors for electrospinning, and the fibers were manufactured by electrospinning and confirmed.

Based on the color change of inorganic composite nanofibers according to heat treatment temperature, TGA analysis was used to confirm the temperature and mass change in the section corresponding to the decomposition substance. TGA was performed on a 2:1 molar ratio fiber sample manufactured in the form of fibers by electrospinning (without heat treatment), and the temperature was increased from room temperature to 700 ℃ at a heating rate of 10 ℃ per minute in air. A mass decrease occurred around 100 ℃ due to the vaporization of DMF solvent and moisture present in the sample. At 245 ℃, acac and isopropoxide corresponding to Ti(acac) ₂ (OiPr) ₂ began to decompose, and at temperatures above 500 ℃, phenyl groups began to thermally decompose, resulting in a mass decrease.

Additionally, in order to confirm the difference with the silane-based fiber depending on the addition of the titania precursor, the PTMS fiber was compared through TGA analysis. The PTMS fiber has a silica and organic group content of approximately 46% and 54%, respectively. According to the TGA results, the residue of the PTMS fiber was 49%. It is judged that organic groups that were not decomposed during the heat treatment may remain. The fiber containing titania showed a residue of 36% due to the heat treatment process, but when converted by calculating the corresponding 10% due to the initial mass loss due to the solvent and moisture, it was confirmed to be approximately 46%. The PTMS fiber rapidly decreased in mass after 600 ℃ as the decomposition of the phenyl group began. Therefore, it was confirmed that the decomposition temperature of the organic group in the composite fiber containing the titania metal precursor occurred at a lower temperature than that of the PTMS fiber itself.

Figure 12 shows the results of confirming the solvent resistance according to the heat treatment of SiO ₂ -TiO ₂ composite nanofibers with a molar ratio of 2:1. In Figure 12, (a) EtOH solvent after drying at 80°C, (b) Acetone solvent after drying at 80°C, (C) DMF solvent after drying at 80°C, and (d) DMF solvent after heat treatment at 300°C were confirmed.

To verify the physical stability of the photocatalytic fibers according to the component ratio and heat treatment, fibers with a molar ratio of 4:1 (Experimental Example 10) and 2:1 (Experimental Example 9) were heat-treated in a vacuum oven at 80°C for 1 hour and 300°C for 1 hour. After the heat treatment, the fibers were added to solvents such as ethanol, acetone, and DMF, and their solubility in these was verified using an optical microscope.

When heat-treated at 80 ℃ for 1 hour, it was confirmed with the naked eye that the fibers dissolved immediately in the solvent because the Ti content was low under conditions of a molar ratio of less than 4:1 and cross-linking of the fibers did not occur by drying alone. On the other hand, under conditions of a molar ratio of 4:1 or more, the fibers did not dissolve in ethanol and acetone after drying, and the shape of the fibers was maintained, and they dissolved in DMF after a period of time.

After heat treatment at temperatures above 300°C, it was confirmed that all fibers manufactured regardless of molar ratio were insoluble in all solvents.

Figure 13 shows the results of comparing XRD of (a) SiO ₂ -TiO ₂ and (b) SiO ₂ -TiO ₂ /Ag composite nanofibers after heat treatment at 1000°C. In Figure 13, (a) is Experimental Example 9, and (b) is Experimental Example 25.

In the case of Ag(ND) used as an Ag precursor, a metal compound was prepared through a reaction of substituting silver nitrate using sodium hydroxide in neodecanoic acid. Carboxylated silver oxide using a carboxylic acid fatty acid does not dissolve in organic solvents, but neodecanoic acid is a fatty acid with a branched chain structure, and since two methyl groups are bonded to the carbon corresponding to the branch structure, a weak bond was formed, so it was confirmed that it was dissolved in an organic solvent. Therefore, Ag(ND) was dissolved in anhydrous DMF, and the titania precursor was added to the solution mixed with the PTMS solution to prepare a precursor solution for electrospinning with a molar ratio of titania (TiO ₂ ) and Ag of 1:1 (Experimental Example 25).

When performing electrospinning, the process variables were fixed as injection rate 1 ml/hr, voltage 8 kV, and TCD 15 cm, and spinning was performed. Referring to Experimental Examples 25 to 28, when the content of titania and silver increased beyond the mixing ratio of titania and silver exceeding 1:1, when a high voltage was applied to the syringe nozzle, cross-linking occurred between the metals in the composite nanofibers, and the phenomenon of the precursor solution for electrospinning solidifying at the syringe tip was confirmed.

In order to confirm the crystal phase change of the fiber sample according to the heat treatment temperature (800 ℃ and 1000 ℃), X-ray diffraction analysis was performed using a sample of titania/silver composite nanofibers (Experimental Example 25). As the temperature increased, the titania/silver composite nanofibers began to show a cubic metallic Ag crystal phase at 800 ℃, and the titania Anatase crystal phase and the Ag crystal phase were confirmed at 1000 ℃. Generally, titania particles grow from an amorphous to an Anatase phase at 200 ℃, and a phase transition occurs to a stable Rutile phase at a temperature of 700 ℃ or higher. On the other hand, the titania in the fibers showed an Anatase crystal phase under the heat treatment condition of 1000 ℃. This is thought to be due to the inhibition of the phase transition by the movement of the titania particles caused by silica.

Additionally, the difference in crystallinity according to heat treatment at 800 ℃ and 1000 ℃ of the titania composite fiber Experimental Example 9 and the silver-doped titania composite fiber Experimental Example 25 was compared. The size of the anatase particles of titania grown during the heat treatment at 1000 ℃ was compared between the two fibers using the Scherrer equation. It was confirmed that titania crystals in the TiO ₂ composite fiber and TiO ₂ /Ag composite fiber were approximately 7.78 nm and 9.45 nm in size, respectively, and silver crystals were formed with a size of 11.35 nm.

Figure 14 shows the results of analysis using TEM of SiO ₂ -TiO ₂ /Ag composite nanofibers after heat treatment at 1000 ℃. Figure 15 shows the results of analysis of specific atomic distributions of (a) Si, (b) Ti, and (c) Ag on the surface of composite nanofibers using SEM-EDX.

In order to confirm the shape of the fiber according to the heat treatment at 1000 ℃ of the TiO ₂ composite nanofibers with added Ag using Experimental Example 25, TEM analysis was performed. Referring to Fig. 14, it was confirmed that the inorganic composite fibers confirmed by TEM appeared as smooth fibers with a diameter of about 533 nm even after the heat treatment at 1000 ℃. The internal shape of the fiber is that the metal precursor is distributed within the fiber in the form of particles close to spherical in shape, with an average crystal size of 18.77 nm (approximately ±0.19 nm).

Since it is difficult to confirm the distribution by type of metal through TEM, the surface of the fiber heat-treated at 1000 ℃ was mapped using SEM-EDX to confirm the distribution of each of Si, Ti, and Ag present on the surface. Figure 15 shows the results of the distribution of atomic components corresponding to Si, Ti, and Ag, respectively. The distribution of Si, Ti, and Ag atoms on the surface of the fiber shows the shape of the fiber and was confirmed to be evenly distributed overall. On the other hand, the component corresponding to a specific element Si seems to be slightly preferentially distributed, and the metal distributions of Ti and Ag seem to be evenly distributed with a similar density as if they correspond to a molar ratio of 1:1.

Figure 16 shows etching TEM images of composite nanofibers heat-treated at 1000°C (a) before etching and (b) after etching.

In order to increase the photodegradation efficiency, an experiment was conducted to etch the surface of TiO ₂ /Ag inorganic composite nanofibers (Experimental Example 25) heat-treated at 1000 ℃ with acid. TEM was used to compare the etching presence and the fiber shapes before and after etching. No changes in color and weight were observed with the naked eye after etching, and the difference in diameter before and after etching was confirmed. Before etching, the fiber had a diameter of 583 nm, and after etching with 0.05% hydrofluoric acid for 10 minutes, it became 433 nm. It was confirmed that approximately 150 nm was etched. Through this, the surface was roughened by etching about half of the fiber diameter for approximately 30 minutes, and then a photodegradation experiment was conducted.

Figure 17 shows the UV spectrum of Rhodamine B photocatalytic degradation results for (a) SiO ₂ -TiO ₂ composite nanofibers, (b) SiO ₂ -TiO ₂ /Ag composite nanofibers, (c) SiO ₂ -TiO ₂ Etching composite nanofibers, and (d) SiO ₂ -TiO ₂ /Ag Etching composite nanofibers, respectively. Figure 18 shows the results of comparing the photocatalytic degradation rates for Rhodamine B.

In Fig. 17, (a) is the case where only a Ti precursor is used as a metal precursor and then heat-treated, (b) is the case where a Ti precursor and an Ag precursor are used and then heat-treated, (c) is the case where the composite nanofibers of (a) are etched with hydrofluoric acid, and (d) is the case where the composite nanofibers of (b) are etched with hydrofluoric acid.

The photocatalytic properties of SiO ₂ -TiO ₂ fibers heat-treated at 1000 ℃ (Experimental Example 9) and SiO ₂ -TiO ₂ /Ag (Experimental Example 25) and fibers manufactured through etching were investigated through a photodecomposition experiment for Rhodamine B. The change in absorbance at 554 nm, which is the maximum absorption wavelength of Rhodamine B, was measured using UV-Vis spectroscopy (S-4100, Scinco). Rhodamine B decomposition was performed for 180 minutes at 30-minute intervals. The change in absorption spectrum according to the UV measurement results was confirmed.

Before UV irradiation, no concentration change due to dye adsorption was observed. When photodegradation was performed for 180 minutes, the samples of SiO ₂ -TiO ₂ , SiO ₂ -TiO ₂ /Ag, SiO ₂ -TiO ₂ Etching, and SiO ₂ -TiO ₂ /Ag Etching composite nanofibers were confirmed to have gradually increased decomposition rates of 51%, 72%, 75%, and 91%, respectively. Using the absorbance data, the degree of dye decomposition over time was calculated by dividing the current concentration by the initial concentration, and the decomposition rate is shown in Fig. 18.

Previous studies have shown that photodegradation of Rhodamine B using TiO ₂ @mercaptopropyl-functionalized silica(TiO ₂ @MPS) particles exhibited 50% photodegradation efficiency in just 10 minutes (GM Bang, YJ Kim, SH Kim, Preparation of Mesoporous Titanium Oxides by Template Synthesis and Phase Transition of TiO2 inside Mesoporous Silica, Korean Chem. Eng. Res ., 2018, 56, 261-268). On the other hand, the photodegradation of SiO ₂ -TiO ₂ , SiO ₂ -TiO ₂ /Ag, SiO ₂ -TiO ₂ Etching, and SiO ₂ -TiO ₂ /Ag Etching composite nanofibers according to the present example all showed a decomposition efficiency of more than 50% after 180 minutes.

In addition, in the previous study of TiO ₂ @mercaptopropyl-functionalized silica(TiO ₂ @MPS) Particles, the molar ratio of silica and titania was mixed at a 1:1 ratio, whereas in the present example, the SiO ₂ -TiO ₂ fibers have a molar ratio of 2:1 and contain a small content of titania, which is a photocatalytic material, and it is judged that they exhibit high decomposition efficiency because they have more reaction sites between titania and dye when they are in the form of particles than when they are present on the surface of the fiber. In addition, the composite nanofibers according to the present example were able to overcome the limitation of dye penetration into titania present in the fiber due to surface etching, and to increase the exposed area with dye in an aqueous solution.

It was confirmed that the photodegradation efficiency of SiO ₂ -TiO ₂ composite nanofibers showed a large difference before and after etching. In the previous study, the fibers were manufactured in the form of a core-shell with a ratio of silica and titania of 2:1 to increase the surface area of the fibers and increase the reaction site from titania to dye, and a decomposition rate of about 90% was observed during a reaction time of 180 minutes (HH Yun, JS Kim, EH Kim, Enhanced photocatalytic activity of _{TiO2@mercapto@functionalized silica toward colored organic dyes, J Mater Sci, 2015, 50, 2577-2586). On the other hand, in the present example, when the decomposition reaction was performed under the same conditions, a decomposition rate of about 80% was observed 120 minutes after surface etching of SiO 2} -TiO ₂ composite nanofibers using acid.

Typically, precious metals such as Pt and Au are mixed into the fibers of TiO ₂ , a photocatalytic material, to enhance the photocatalytic performance. However, the synthesis process is complex, which causes deformation of the TiO ₂ crystal structure and has the disadvantage of high cost.

On the other hand, the composite nanofibers according to the present example were able to efficiently manufacture composite nanofibers by introducing Ag into the fibers of TiO ₂ . In addition, when Ag was introduced, a decomposition rate of about 60% was shown for 180 minutes. It was confirmed that the efficiency tended to improve when Ag was introduced compared to when only titania was present. Additionally, when the etching process was performed, it was confirmed that all of the Rhodamine B dye was decomposed in just 120 minutes. The photodecomposition reaction was greatly improved in photodecomposition efficiency due to the exposed surface area of titania or silver. It is judged that Ag nanoparticles suppress the binding reaction of excited electrons and positive spaces in TiO ₂ , and that the Ag nanoparticles themselves also increase the photocatalytic efficiency.

In Experimental Examples 1 to 8, PTMS particles and PTMS/VTMS particles were dissolved in anhydrous DMF to have various solid contents, and it was confirmed whether the electrospinning process was performed using an electrospinning device. In Experimental Examples 1 to 8, the solvent was evaporated to the same viscosity of 140 poise, and then the electrospinning process was performed. When performing electrospinning, the process variables were fixed to an injection speed of 1 ml/hr, a voltage of 8 kV, and a TCD of 15 cm, and spinning was performed. As a result of performing the electrospinning process, it was confirmed that the nozzle was not clogged and that the particles were well spun into a fiber shape. That is, it was confirmed that a solid content of 68 wt% to 74 wt% of PTMS or PTMS/VTMS can all be appropriately used for electrospinning, and that the solid content can be controlled depending on the properties of the composite nanofiber or the characteristics of the metal precursor and used as a precursor solution for electrospinning.

In Experimental Examples 13 to 16, precursor solutions for electrospinning were prepared using Er precursors at various molar ratios of metals, and electrospinning was performed. When performing electrospinning, the process variables were fixed to an injection rate of 1 ml/hr, a voltage of 8 kV, and a TCD of 15 cm. The concentration of PTMS particles in the PTMS solution in which the PTMS particles were dissolved was kept the same, and the molar ratio of Er(acac) ₃ , which is an Er precursor added, was variously changed to 4:1, 2:1, 1.5:1, and 1:1. When the molar ratio was 4:1, the content of Er included in the prepared composite nanofibers was too low, and when the molar ratio was 1:1, electrospinning was impossible.

In Experimental Examples 17 to 20, precursor solutions for electrospinning were prepared at various molar ratios using Ag precursors. Electrospinning was performed at a fixed injection rate of 1 ml/hr, voltage of 8 kV, and TCD of 15 cm. As the content of Ag(ND), which is the added Ag precursor, increased, it became difficult to prepare fibers during electrospinning, but electrospinning was performed well in the ranges of 4:1, 2:1, and 1.5:1.

In Experimental Examples 21 to 24, precursor solutions for electrospinning were prepared at various molar ratios using Pr-EAA precursors. Electrospinning was performed at a fixed injection rate of 1 ml/hr, voltage of 8 kV, and TCD of 15 cm. Similar to the other metal precursors described above, it was confirmed that electrospinning was possible at other molar ratios, but electrospinning was not possible when the molar ratio was 1:1. That is, it was confirmed that similar effects were exhibited even when the ligand bound to the metal of Pr(EAA) ₃ in the form of silver neodecanoate (AgND) or the like was different as in the present example, as in other examples.

In Experimental Examples 30 to 47, precursor solutions for electrospinning were prepared under the same conditions using various metal precursors prepared according to Preparation Examples 3 to 30, and electrospinning was performed under the same conditions. Electrospinning was performed at a fixed injection rate of 1 ml/hr, voltage of 8 kV, and TCD of 15 cm. The composite nanofibers prepared according to Experimental Examples 30 to 47 had similar thicknesses (in the range of approximately 500 nm to 550 nm), and electrospinning was performed well for all of them. In addition, it was confirmed that the composite nanofibers were prepared with uniform thickness and overall uniform physical properties, even when they were prepared in large quantities.

In Experimental Examples 48 to 51, precursor solutions for electrospinning were prepared using a Ti precursor. At this time, the temperature and time for heating the precursor solution for electrospinning were changed to control the viscosity of the prepared precursor solution for electrospinning to be different. When the viscosity of Experimental Example 48 was 100 poise, electrospinning was difficult, and when the viscosity of Experimental Example 51 was 200 poise, electrospinning was performed, but the thickness of the prepared composite nanofibers was not uniform.

In a composite nanofiber according to an embodiment of the present invention, spherical PTMS particles were prepared as an organic-inorganic hybrid composite material in which a portion of the network structure of siloxane is bonded to an organic group, and an electrospinning solution was prepared using the prepared particles without using an organic polymer in the electrospinning process. Functional fibers were prepared based on PTMS, which is an organic silane, through electrospinning. Composite nanofibers with a uniform thickness of several hundred nm were prepared by controlling the process variables of solution concentration, electrospinning voltage, and release rate during fiber preparation.

Inorganic materials were added to functional fibers based on phenyl for various applications. Various metal precursors, including Ti precursors, were mixed with a solution containing organic silsesquioxane and spun to prepare a ratio of a spinnable solution. In order to understand the changes in the fibers according to the heat treatment temperature, the chemical structure after heat treatment, and the physical shape changes according to the solvent were analyzed. When the metal precursors were mixed during the heat treatment, the phenyl group was thermally decomposed at a lower temperature than in the phneyl group-based PTMS fibers and converted to SiO ₂ -TiO ₂ fibers, and it was confirmed that titania in the anatase crystal phase was evenly distributed in the fibers through the 1000 ℃ heat treatment process. In addition, even when an Ag precursor was further introduced after the introduction of the Ti precursor, it was confirmed through the analysis of the crystallinity of the metal according to the heat treatment temperature that the chemical structure and physical shape of the fibers did not change significantly. Through a heat treatment process at 800°C, a cubic silver crystal phase appeared, and at 1000°C, an anatase crystal phase of titania appeared together, producing a composite nanofiber in which silver and titania were evenly distributed.

Titania, a representative photocatalytic material, is mainly used in the form of nanoparticles. However, this study attempted to overcome the problems of dispersibility due to nanoparticles in aqueous solution and rapid recombination of electrons and holes excited by light, which lowers the photocatalytic efficiency. One of the methods to generally solve the problem of lowering the photocatalytic efficiency of TiO ₂ is to mix in expensive noble metals such as Pt and Au, but the synthesis process is complicated, which causes deformation of the TiO ₂ crystal structure and has the disadvantage of high cost. To solve this problem, Ag was introduced to manufacture SiO ₂ -TiO ₂ /Ag composite fibers. Etching was performed on the SiO ₂ -TiO ₂ /Ag composite fibers to increase the photodegradation efficiency. The photodegradation efficiency was confirmed in the fibers both before and after etching.

The possibility of manufacturing functional nanofibers with excellent thermal and physical stability was confirmed by manufacturing organic/inorganic composite nanofibers containing various metal precursors based on pure organic silane through the electrospinning process. The manufactured various metal oxide nanofibers are expected to be utilized in various fields such as sensors, catalysts, and batteries by utilizing their large surface area and porous structure.

Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing its technical idea or essential characteristics. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims (24)

A step of preparing a first solution by mixing an organosilicon compound and a first organic solvent and adding a metal compound;
A step of preparing an electrospinning solution by heating the first solution to have a first viscosity;
A step of manufacturing a fiber precursor in the form of fibers by electrospinning the above electrospinning solution; and
A method for manufacturing a composite nanofiber, comprising: a step of heat-treating the fiber precursor at a first temperature. In the first paragraph,
The above organosilicon compound has a three-dimensional structure,
The viscosity of the first solution is 50 poise to 100 poise at 25°C,
A method for producing composite nanofibers, wherein the first viscosity of the electrospinning solution is 120 poise to 180 poise at 25°C. In the first paragraph,
The above organic silicon compound is provided in particle form,
A method for manufacturing composite nanofibers having the above particle shape and an average particle diameter of 50 nm to 5 μm. In the first paragraph,
The above glass silicon compound is provided in the form of particles having functional groups on the surface,
A method for producing a composite nanofiber, wherein the functional group includes at least one of a cyanogen group, an amine group, a hydroxyl group, a carboxyl group, a halide group, a nitrate group, a thiocyanate group, and a thiosulfate group. In the first paragraph,
A method for producing a composite nanofiber, wherein the above organosilicon compound is represented by the following chemical formula 1 or chemical formula 2 and includes a solid powder in the form of spherical particles or pellets of ormosil.
(chemical formula 1)
(R1SiO _3/2 )
(chemical formula 2)
(R1SiO _3/2 )-(R2SiO _3/2 )
In the above chemical formula 1 or chemical formula 2, R1 is a substituted or unsubstituted C _5-15 aryl group, and R2 is independently selected from the group consisting of hydrogen, a substituted or unsubstituted C _1-18 alkyl group, and a substituted or unsubstituted C _5-15 aryl group. In paragraph 5,
A method for producing a composite nanofiber, wherein the above R1 is a phenyl group, R2 is a substituted or unsubstituted C _1-3 alkyl group, and a substituted or unsubstituted C _5-15 aryl group. In Article 6,
The above R1 is a phenyl group, R2 is a phenyl group or a substituted or unsubstituted C _1-3 alkyl group,
A method for manufacturing a composite nanofiber having a molar ratio of R1:R2 of 10:0 to 5. In the first paragraph,
A method for producing composite nanofibers, wherein the first organic solvent comprises at least one of tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N-methylformamide (NMF), N-methylpyrrolidone (NMP), acetone, and an amine solvent. In the first paragraph,
The step of preparing the first solution further includes preparing the organosilicon compound,
The step of manufacturing the above organosilicon compound is:
After adding the first base solution silane compound, a solid is prepared by stirring at 150 rpm to 500 rpm at a temperature of 50 ℃ to 80 ℃,
The above solid comprises filtering and drying,
A method for producing a composite nanofiber, wherein the above organosilicon compound comprises at least one of phenyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, chloropropyltrimethoxysilane, 2-phenylethyltrimethoxysilane, chloropropylmethoxysilane, and 2-phenylethyltrimethoxysilane. In the first paragraph,
The step of preparing the first solution further includes preparing the metal compound using a metal element,
The production of the above metal compound comprises:
After adding the ligand to the second base solution, stir at 40°C to 60°C for 0.5 to 3 hours.
A metal solution containing the above metal elements is added and stirred for 0.5 to 3 hours to produce a precipitate.
After filtering and washing the above sediment three or more times, it is dried in an oven and manufactured into a powder form.
A method for manufacturing a composite nanofiber, wherein the metal element is selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, Cd and Yb. In the first paragraph,
A method for producing composite nanofibers, wherein the electrospinning solution is heated at a temperature of 50° C. to 110° C. to evaporate the solvent so that the electrospinning solution is 50 wt% to 90 wt% based on the total weight of the first solution. In the first paragraph,
The above electrospinning solution is a method for manufacturing composite nanofibers comprising a mixture of an inorganic polymer-resin type compound of ormosil represented by the following chemical formula 3 and a metal precursor:
(chemical formula 3)
(RSiO _3/2 ) + MLx
Here, R is a substituted or unsubstituted C _5-15 aryl group,
M is selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, and Yb,
L is selected from the group consisting of -NO ₃ , -OR (R is C _1-6 alkyl), -NR ₂ (R is C _1-6 alkyl), -COOR (R is C _1-6 alkyl), acetate, acetylacetonate, beta-ketonate, diamide, and ditholate,
x is the number of ligands depending on the oxidation number of M. In Article 12,
A method for producing a composite nanofiber, wherein the above L is a type of organometallic complex selected from the group consisting of -OR (R is C _1-6 alkyl), -NR ₂ (R is C _1-6 alkyl), -COOR (R is C _1-6 alkyl), acetylacetonate, beta-ketonate, diamide, and ditholate, which exhibit high solubility in organic solvents. In Article 12,
A method for producing composite nanofibers, wherein the organosilicon compound and the metal compound are mixed in a molar ratio of 1:0.1 to 1 in the electrospinning solution. In the first paragraph,
The above electrospinning is performed using a single nozzle.
A method for producing composite nanofibers, wherein the electrospinning solution is performed under the conditions of a spinning voltage of 8-15 kV, a spinning distance of 10-30 cm, and a spinning flow rate of 1-3 mL/hr. In the first paragraph,
The above first temperature is less than 200 ℃ to 600 ℃,
A method for manufacturing a composite nanofiber, wherein the composite nanofiber is in the form of an organic-inorganic hybrid containing carbon. In the first paragraph,
The above first temperature is 600 ℃ to 1500 ℃,
A method for manufacturing a composite nanofiber, wherein the composite nanofiber is in the form of an inorganic hybrid containing SiO ₂ and a metal. In the first paragraph,
After the step of heat-treating the fiber precursor at the first temperature, a post-treatment step is further included,
The above post-processing step is,
A method for manufacturing a composite nanofiber, comprising surface-treating or etching the heat-treated fiber precursor. In Article 18,
The above etching process is a method for manufacturing a composite nanofiber by etching the surface of the heat-treated fiber precursor using a hydrofluoric acid solution to form holes and increase the surface area. A composite nanofiber manufactured according to a manufacturing method according to any one of claims 1 to 19. In Article 20,
The above composite nanofiber is a composite nanofiber having a diameter of 100 to 1000 nm. In Article 20,
The above composite nanofibers contain one or more metal particles,
The above metal particles have a diameter of 5 nm to 70 nm,
A composite nanofiber wherein the metal particles are selected from the group consisting of Li, Cs, Be, Mg, Ca, Ba, Sr, Al, Ga, In, Ge, Ge, Sn, Pb, As, Sb, Ti, Zr, Cu, Ag, Er, Pr, Cd and Yb. A fabric or film-shaped material manufactured using composite nanofibers according to Article 20. An organic-inorganic composite resin material manufactured using a composite nanofiber and a polymer resin according to Article 20.