JP2007327148A - Polyelectrolyte fiber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a new polyelectrolyte fiber. <P>SOLUTION: The method for producing the new polyelectrolyte fiber is to use a solution containing a polyelectrolyte, a sol/gel reaction precursor and a sol/gel reaction catalyst and to produce the fiber by electrospray deposition method. Although not necessarily limited, the polyelectrolyte preferably is a high molecular compound having a plurality of charged groups; the charged group is either one selected from negative charge groups, positive charge groups and amphoteric charge groups or a combination of either two or more species of the groups. The sol/gel reaction precursor preferably comprises a metal alkoxide, but it is not limited. The sol/gel reaction catalyst preferably comprises an acid or a base, but it is not limited. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a novel polyelectrolyte fiber.
The present invention also relates to a novel method for producing a polymer electrolyte fiber.

  Fibers with charged groups, so-called “ion exchange fibers”, are used in organic synthesis from filters in separation, purification, and purification processes for the purpose of adsorption removal of gas components in the gas phase and removal of ionic substances in the liquid phase. Even catalysts are widely used.

  Conventionally, the production of ion exchange fibers includes (1) a method of introducing charged groups into fibers such as polyolefin or hollow fibers, (2) a method of introducing charged groups into fibers produced by composite spinning, and (3) glass fibers. For example, a method of coating the surface of this material with an ion exchange resin has been used. In such a method, the diameter of the fiber used as the base material for introducing the charged group is several microns or more, and the specific surface area is increased by reducing the diameter of the fiber in order to realize a high-efficiency process using the ion exchange fiber. Is required. Moreover, in the conventional manufacturing method, since charged groups are introduced after spinning of a polymer or an inorganic material, a plurality of steps are required, and the manufacturing cost is high.

  On the other hand, the electrospray deposition method, which is a microfabrication technology using an electric field, can produce fibers with diameters on the order of nano to micron easily at room temperature and atmospheric pressure. (See, for example, Non-Patent Document 1). Furthermore, in the electrospray deposition method, a hollow fiber having a diameter of nano to micron order can be produced in one step by using a coaxial double tube as a spray nozzle (see, for example, Non-Patent Document 2). .

  Production of polyelectrolyte fibers using the electrospray deposition method has already been reported for the production of polyelectrolyte fibers having a weak electrolyte such as an amino group or a carboxyl group as a charged group (for example, Non-Patent Document 3 and (Refer nonpatent literature 4.).

  In addition, by introducing a sulfonic acid group or a quaternary base into a polymer fiber produced using the electrospray deposition method by secondary chemical treatment, a polymer fiber having a strong electrolyte as a charged group is produced. (For example, see Non-Patent Document 5.)

Supervised by Tatsuya Motomiya, Advanced industrial excavation strategy using nanofiber technology, CM Publishing Company, 2004 I. G. Loscrertales, A. Barrero, M. Marquez, R. Spretz, R. Velarde-Oritz, G. Larsen, J. Am. Chem. Soc. 2004, 126, 5376-5377. L. Li, Y.-L. Hsieh, Polymer 2005, 46, 5133-5139. M. G. McKee, M. T. Hunley, J. M. Layman, T. E. Long, Macromolecules 2006, 39, 575-583. H. Matsumoto, Y. Wakamatsu, M. Minagawa, A. Tannioka, J. Colloid Interface Sci., 2006, 263, 143-150.

  As described above, the production of polymer electrolyte fibers using the electrospray deposition method has already been reported on the production of polymer electrolyte fibers having a weak electrolyte such as an amino group or a carboxyl group as a charged group.

  However, it is considered difficult to fiberize a polymer electrolyte using a strong electrolyte such as a sulfonic acid group or a quaternary base as a charged group. Electrospray is a phenomenon based on electrostatic repulsion between charges induced on the solution surface at the tip of the spray nozzle by an electric field. Therefore, in a solution having high electrical conductivity such as a polymer electrolyte having a strong electrolyte as a charged group, It is considered that the reason is that the electric charge induced by the electric field flows as an electric current in the solution, thereby preventing the charge accumulation on the solution surface at the nozzle tip (charging relaxation).

  In addition, by introducing a sulfonic acid group or a quaternary base into a polymer fiber produced using the electrospray deposition method by secondary chemical treatment, a polymer fiber having a strong electrolyte as a charged group is produced. Yes.

  However, this method requires a reaction step of introducing a charged group after spinning, leading to an increase in production cost.

Therefore, development of a novel polymer electrolyte fiber that solves such problems is desired.
In addition, development of a method for producing a novel polymer electrolyte fiber is desired.

The present invention has been made in view of such problems, and an object thereof is to provide a novel polymer electrolyte fiber.
Another object of the present invention is to provide a novel method for producing a polymer electrolyte fiber.

  In order to solve the above problems and achieve the object of the present invention, the polymer electrolyte fiber of the present invention includes a polymer electrolyte and a sol-gel reaction product.

  Here, although not limited, the polymer electrolyte is a polymer compound having a plurality of charged groups, and the charged groups include a carboxyl group, a phosphate group, a negatively charged group of a sulfonate group, an amino group. , Pyridyl group, imidazole group, quaternary ammonium group, quaternary pyridinium base, quaternary imidazole group positively charged group, betaine group, phosphatidylcholine group, amphoteric charged group of amino acid group, or any two It is preferable to consist of a combination of more than one species.

  Further, although not limited, the polymer electrolyte is a copolymer of perfluorosulfonic acid and polytetrafluoroethylene, polystyrene sulfonic acid and its copolymer, sulfonated polysulfone, sulfonated polyetheretherketone, sulfuric acid. Cellulose, carboxymethylcellulose, polyacrylic acid, polyvinylpyridine and its quaternized product, polyvinylbenzyltrimethylammonium, polyallylamine, polyethyleneimine and its quaternized product, 2-methacryloyloxyethyl phosphorylcholine homopolymer and copolymer It is preferable to consist of any one type or a combination of any two or more types.

  Although not limited, the sol-gel reaction product is a reaction product from a sol-gel reaction precursor, the sol-gel reaction precursor is made of a metal alkoxide, and the metal of the metal alkoxide. Consists of any one selected from Si, Ta, Nb, Ti, Zr, Al, Ge, B, Na, Ga, Ce, V, Ta, P, Sb, or a combination of any two or more, The alkoxy group of the metal alkoxide is any one selected from an alkoxy group having a carbon number n (n is an integer of 1 to 8), including a methoxy group, an ethoxy group, a propoxy group, and a butoxy group, or any two It is preferable to consist of a combination of more than one species.

  Moreover, although not necessarily limited, electrolyte fiber can have a hollow structure.

  In the method for producing a polymer electrolyte fiber of the present invention, a fiber is produced by an electrospray deposition method using a solution containing a polymer electrolyte, a sol-gel reaction precursor, and a sol-gel reaction catalyst.

  Here, although not limited, the polymer electrolyte is a polymer compound having a plurality of charged groups, and the charged groups include a carboxyl group, a phosphate group, a negatively charged group of a sulfonate group, an amino group. , Pyridyl group, imidazole group, quaternary ammonium group, quaternary pyridinium base, quaternary imidazole group positively charged group, betaine group, phosphatidylcholine group, amphoteric charged group of amino acid group, or any two It is preferable to consist of a combination of more than one species.

  Further, although not limited, the polymer electrolyte is a copolymer of perfluorosulfonic acid and polytetrafluoroethylene, polystyrene sulfonic acid and its copolymer, sulfonated polysulfone, sulfonated polyetheretherketone, sulfuric acid. Cellulose, carboxymethylcellulose, polyacrylic acid, polyvinylpyridine and its quaternized product, polyvinylbenzyltrimethylammonium, polyallylamine, polyethyleneimine and its quaternized product, 2-methacryloyloxyethyl phosphorylcholine homopolymer and copolymer It is preferable to consist of any one type or a combination of any two or more types.

  Although not limited, the sol-gel reaction precursor is made of a metal alkoxide, and the metal of the metal alkoxide is Si, Ta, Nb, Ti, Zr, Al, Ge, B, Na, Ga, Ce. , V, Ta, P, or Sb, or a combination of any two or more thereof, and the alkoxy group of the metal alkoxide includes a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. It is preferably composed of any one selected from alkoxy groups having the number n (n is an integer of 1 to 8), or any combination of two or more.

  Although not limited, the sol-gel reaction catalyst comprises an acid or a base, and the acid is any one selected from hydrochloric acid, sulfuric acid, nitric acid, inorganic acids of boric acid, acetic acid, and organic acids of citric acid. Preferably, the base is composed of one kind or a combination of two or more kinds, and the base is composed of ammonia.

Moreover, although not necessarily limited, it is preferable that a solution contains a fiberization promoter.
Moreover, although not necessarily limited, the fiberization accelerator is composed of any one selected from polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyhydroxyethyl methacrylate, and polyacrylamide, or a combination of any two or more. It is preferable.

  The present invention has the following effects.

  Since the present invention includes a polymer electrolyte and a sol-gel reaction product, a novel polymer electrolyte fiber can be provided.

  The present invention uses a solution containing a polymer electrolyte, a sol-gel reaction precursor, and a sol-gel reaction catalyst to produce fibers by an electrospray deposition method, and therefore provides a novel method for producing polymer electrolyte fibers. can do.

  Hereinafter, the best mode for carrying out the invention relating to a polymer electrolyte fiber and a method for producing the same will be described.

  A method for producing the polymer electrolyte fiber will be described. The method for producing a polymer electrolyte fiber is a method for producing a fiber by an electrospray deposition method using a solution containing a polymer electrolyte, a sol-gel reaction precursor, and a sol-gel reaction catalyst.

  A polymer electrolyte is a polymer compound having many charged groups. As the charged group, a negatively charged group such as a carboxyl group, a phosphoric acid group, and a sulfonic acid group, a positively charged group such as an amino group, a pyridyl group, an imidazole group, a quaternary ammonium group, a quaternary pyridinium base, and a quaternary imidazole group, Any one type selected from amphoteric charged groups such as a betaine group, a phosphatidylcholine group, and an amino acid group, or a combination of any two or more types can be adopted.

  Specific examples of the polymer electrolyte include a copolymer of perfluorosulfonic acid and polytetrafluoroethylene (for example, Nafion (registered trademark)), polystyrene sulfonic acid and its copolymer, sulfonated polysulfone, and sulfonated polyether ether. Ketone, cellulose sulfate, carboxymethylcellulose, polyacrylic acid, polyvinylpyridine and its quaternized product, polyvinylbenzyltrimethylammonium, polyallylamine, polyethyleneimine and its quaternized product, homopolymer and copolymer of 2-methacryloyloxyethyl phosphorylcholine Any one type selected from the above or a combination of any two or more types can be adopted.

  The concentration of the polymer electrolyte is preferably in the range of 1 to 50% by mass. The concentration of the polymer electrolyte is more preferably in the range of 5 to 20% by mass.

  When the concentration of the polymer electrolyte exceeds 50% by mass, the charge relaxation phenomenon occurs due to an increase in solution electric conduction, and there is a possibility that no spray is generated even when an electric field is applied. In particular, when the charged group of the polymer electrolyte is a strong electrolyte, the concentration is preferably 20% by mass or less.

  If the concentration of the polymer electrolyte is less than 5% by mass, it may be difficult for the formed body to form a uniform fiber structure by spraying. In particular, when the concentration of the polymer electrolyte is less than 1% by mass, this effect may become more remarkable.

  The sol-gel reaction precursor will be described. In the sol-gel reaction, a metal compound is used as a starting material (precursor). In particular, metal alkoxide is preferable as a sol-gel reaction precursor because it is highly reactive and forms a metal oxide sol having an oxygen-metal-oxygen bond in a solution. In addition to the metal alkoxide, an acid or a base can be added to the sol-gel reaction precursor solution as a hydrolysis catalyst. Moreover, the solvent for diluting the water for promoting a hydrolysis and a precursor solution can also be added as needed.

  The metal alkoxide used as the sol-gel reaction precursor is selected from Si, Ta, Nb, Ti, Zr, Al, Ge, B, Na, Ga, Ce, V, Ta, P, Sb, etc. 1 type or the combination of any 2 or more types can be adopted. Since the sol-gel reaction precursor used in the electrospray deposition method is preferably a liquid, Si and Ti are particularly preferable. As an alkoxy group, any 1 type chosen from the alkoxy group which has carbon number n (n is an integer of 1-8) including a methoxy group, an ethoxy group, a propoxy group, and a butoxy group, or any 2 or more types Combinations can be employed. More preferred are methoxy and ethoxy. Particularly preferred metal alkoxides include tetramethoxysilane and tetraethoxysilane.

  The concentration of the metal alkoxide serving as the sol-gel reaction precursor is preferably in the range of 0.1 to 50% by mass. Further, the concentration of the metal alkoxide is more preferably in the range of 0.5 to 10% by mass.

  When the concentration of the metal alkoxide is 0.1% by mass or more, there is an advantage that charging relaxation during application of an electric field can be suppressed. This effect becomes more remarkable when the concentration of the metal alkoxide is 0.5% by mass or more.

  When the concentration of the metal alkoxide is 50% by mass or less, there is an advantage that the ratio of the polymer electrolyte component contained in the prepared fiber is increased. When the concentration of the metal alkoxide is 10% by mass or less, in addition to this effect, the fiber diameter is further reduced.

  An acid or base is used as the sol-gel reaction catalyst. As the acid, any one selected from inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and boric acid, and organic acids such as acetic acid and citric acid, or a combination of any two or more can be employed. As the base, volatile ammonia which can be easily removed after the reaction is used. In the production of fibers and hollow fibers using the electrospray deposition method, an acid catalyst that promotes the formation of a linear inorganic polymer is preferred.

  The concentration of the acid constituting the sol-gel reaction catalyst is preferably in the range of 0.01 to 5% by mass. The acid concentration is more preferably in the range of 0.05 to 1% by mass.

  When the acid concentration is 0.01% by mass or more, the molecular weight of the inorganic molecules increases due to the progress of the hydrolysis / condensation reaction, and there is an advantage that charging relaxation during application of an electric field can be suppressed. When the acid concentration is 0.05% by mass or more, this effect becomes more remarkable.

  When the acid concentration is 5% by mass or less, there is an advantage that it is possible to avoid a decrease in spinnability of the polymer electrolyte solution accompanying an increase in the molecular weight of the inorganic molecules due to the progress of the hydrolysis / condensation reaction. This effect becomes more remarkable when the concentration of the acid is 1% by mass or less.

The concentration of the base constituting the sol-gel reaction catalyst is preferably in the range of 1.0 × 10 ^{−7 to} 2.0 × 10 ⁻⁴ mass%. Further, the concentration of the base is more preferably in the range of 5.0 × 10 ^{−7 to} 2.0 × 10 ⁻⁶ mass%.

When the concentration of the base is 1.0 × 10 ⁻⁷ mass% or more, the molecular weight of the inorganic molecules increases due to the progress of the hydrolysis / condensation reaction, and there is an advantage that charging relaxation at the time of applying an electric field can be suppressed. This effect becomes more remarkable when the concentration of the base is 5.0 × 10 ⁻⁷ mass% or more.

The advantage that when the base concentration is 2.0 × 10 ⁻⁴ mass% or less, it is possible to avoid a decrease in the spinnability of the polymer electrolyte solution accompanying an increase in the molecular weight of the inorganic molecules due to the progress of the hydrolysis and condensation reaction. There is. This effect becomes more remarkable when the concentration of the base is 2.0 × 10 ⁻⁶ mass% or less.

  In the method for producing a polyelectrolyte fiber, a fiberization accelerator can be included in the solution. As a fiberization accelerator compatible with the metal alkoxide which is a sol-gel precursor, any one selected from hydrophilic polymers such as polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyhydroxyethyl methacrylate, polyacrylamide, Or any 2 or more types of combination is employable.

  It is preferable that the density | concentration of a fiberization accelerator exists in the range of 0.01-10 mass%. The concentration of the fiberization accelerator is more preferably in the range of 0.1 to 5% by mass.

  When the concentration of the fiberization accelerator is 0.01% by mass or more, there is an advantage that the spinnability is improved by the effect of the fiberization accelerator. This effect becomes more remarkable when the concentration of the fiberization accelerator is 0.1% by mass or more.

  There exists an advantage that the ratio of the polymer electrolyte contained in the produced polymer electrolyte fiber becomes large as the density | concentration of a fiberization promoter is 10 mass% or less. This effect becomes more prominent when the concentration of the fiberization accelerator is 5% by mass or less.

  As the solvent for the polymer electrolyte solution, water, methanol, ethanol, 1-propyl alcohol, 2-propyl alcohol, butanol, acetic acid, protic polar solvents such as formic acid, acetone, methyl ethyl ketone, acetonitrile, N, N-dimethylformamide, Aprotic polar solvents such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, hexane, cyclohexane, cyclohexanone, dichloromethane, dichloroethane, trichloroethane, chloroform, trichloroethylene, benzene, ethylbenzene, xylene, toluene, diethyl Any one selected from the group of nonpolar solvents such as ether, 1,4-dioxane, methyl acetate, ethyl acetate, tetrahydrofuran, and methylene chloride, or any Mixture may be employed either of two or more combinations.

  In the method for producing a polymer electrolyte fiber, an electrolyte fiber having a hollow structure can be produced by using a coaxial double tube nozzle (described later). The core forming agent supplied to the inner tube of the coaxial double tube nozzle is preferably a hydrophobic liquid that is not compatible with the polymer electrolyte solution (outer tube solution) containing a sol-gel precursor such as mineral oil. In addition, a polymer solution that is not compatible with the outer tube solution may be employed.

  The applied electric field between the nozzle and the conductive substrate (described later) is preferably in the range of 5 to 500 kV / m. An electric field of at least about 5 kV / m is necessary for the phenomenon of electrospray. As the electric field strength increases, the sprayability and spinnability improve, but when the applied voltage exceeds 500 kV / m, the spray state at the nozzle tip becomes unstable.

  The supply flow rate of the syringe in a nozzle composed of a single tube (described later) is preferably in the range of 1 to 500 μL / min. When the supply flow rate of the syringe is 1 μL / min or more, there is an advantage that a stable spray state can be maintained for a long time without insufficient solution supply at the nozzle tip. When the supply flow rate of the syringe is 500 μL / min or less, there is an advantage that a stable spray state without dripping from the nozzle tip can be maintained for a long time.

  The supply flow rate of the syringe in the inner tube of the coaxial double tube nozzle is preferably in the range of 0.1 to 500 μL / min. When the supply flow rate of the syringe is smaller than 0.1 μL / min, formation of the hollow structure may be hindered. When the supply flow rate of the syringe exceeds 500 μL / min, there is a possibility that a stable spray cannot be maintained when an electric field is applied.

  The supply flow rate of the syringe in the outer tube of the coaxial double tube nozzle is preferably in the range of 1 to 500 μL / min. If the supply flow rate of the syringe is less than 1 μL / min, formation of a uniform hollow structure may be hindered. When the supply flow rate of the syringe exceeds 500 μL / min, there is a possibility that a stable spray cannot be maintained when an electric field is applied.

  In the method for producing a polymer electrolyte fiber, the spinning temperature is preferably in the range of 10 to 50 ° C. When the spinning temperature exceeds 50 ° C., the solvent may evaporate in some polymer electrolyte solutions. If the spinning temperature is less than 10 ° C., the solvent may be solidified in some polymer electrolyte solutions.

  The polymer electrolyte fiber produced by the method of the present invention will be described.

The polymer electrolyte fiber contains a polymer electrolyte and a sol-gel reaction product.
The sol-gel reaction product is a reaction product from a sol-gel reaction precursor. In the metal alkoxide which is one of the sol-gel reaction precursors, a hydrolysis reaction and a dehydration or dealcohol condensation reaction proceed under a sol-gel reaction catalyst to produce a polymer composed of a metal-oxygen bond. . In particular, when the metal is silicon, a polymer (polysiloxane) composed of a silicon-oxygen bond (siloxane bond) is produced. In electrospray deposition, it is considered that the hydrolysis reaction first proceeds in the solution, and then the polycondensation reaction proceeds with the evaporation of the solvent in the electrospray.

  The average fiber diameter of the polymer electrolyte fiber is preferably in the range of 5 nm to 50 μm. The average fiber diameter of the polymer electrolyte fiber is more preferably in the range of 50 nm to 5 μm.

  When the average fiber diameter of the polymer electrolyte fiber is 50 μm or less, an effect of increasing the specific surface area of the polymer electrolyte fiber and the polymer electrolyte fiber aggregate can be expected. This effect becomes more prominent as the average fiber diameter decreases. When the fiber diameter is nano-order, the mechanical strength of one fiber is not sufficient and handling becomes difficult, so the average fiber diameter is preferably 5 nm or more, and more preferably 50 nm or more.

  Examples of the polymer electrolyte fiber aggregate include those in which a nonwoven fabric, a membrane, a membrane module, and a polymer electrolyte fiber are integrated with a support such as a substrate or a porous body.

  From the above, according to the best mode for carrying out the present invention, the following effects can be obtained.

  The present inventors noted that the curing of the sol-gel reaction precursor is accelerated by solvent evaporation, and the charging relaxation phenomenon at the nozzle tip is suppressed by adding the sol-gel reaction precursor to the polymer electrolyte solution. We found out that we could do this, and realized the spinning of polymer electrolytes by electrospray deposition. Since the fiber size can be easily controlled in the production method of the present invention, a polymer electrolyte fiber having a diameter of nano to micro scale can be efficiently produced at normal temperature and atmospheric pressure.

In addition, it was found that a polymer electrolyte solution having a sol-gel reaction precursor can be used to produce a polymer electrolyte fiber having a hollow structure by an electrospray deposition method using a coaxial double tube nozzle.
Moreover, those aggregates can be efficiently produced from fibers or hollow fibers made of a polymer electrolyte having a diameter of nano to micron order.

  Such fibers or fiber aggregates can be used for water treatment materials, filter materials, fuel cell materials, sensor materials and the like. Nano- to micro-scale hollow polymer electrolyte fibers are novel ion exchange materials, and are expected to be developed into high-capacity hollow fiber membrane modules, nano / microfluidic devices, and nano / microtube fuel cells.

  The present invention is not limited to the best mode for carrying out the above-described invention, and various other configurations can be adopted without departing from the gist of the present invention.

  Next, specific examples of the present invention will be described. However, it goes without saying that the present invention is not limited to these examples.

[Example 1] (Effect of addition of sol-gel reaction precursor and sol-gel reaction catalyst)

<Preparation of sample solution>
Commercially available 20% by mass Nafion solution (DE2021, manufactured by Wako Pure Chemical Industries, Ltd., solvent 34% by mass water and 44% by mass 1-propanol), tetraethoxysilane (TEOS, Kanto Chemical Co., Ltd. organic synthesis reagent) and boric acid (H ₃ BO ₃ , a Wako Pure Chemicals special grade reagent) was added to prepare a sample solution. In this solution, the polymer electrolyte (Nafion) concentration was 13.1% by mass, the sol-gel reaction precursor (TEOS) concentration was 1.6% by mass, and the sol-gel reaction catalyst (H ₃ BO ₃ ) concentration was 0. 2% by mass. Nafion is a perfluorosulfonic acid and polytetrafluoroethylene copolymer, and is a fluorine-based polymer electrolyte having a sulfonic acid group, which is a strong electrolyte, as a charged group. Since it is a polymer electrolyte excellent in chemical stability and proton conductivity, it is used as an electrolyte membrane for fuel cells, a sensor material, and a catalyst.

<Production of polymer electrolyte fiber>
An apparatus as shown in FIG. 1 was used for the electrospray deposition method. The apparatus is composed of a DC high-voltage stabilized power supply 1 (HDV-20K manufactured by Pulse Electronics Industry), a syringe pump 2 (MCIP-III manufactured by Minato Concept), and a conductive substrate 3 (aluminum plate). The sample solution is placed in a glass syringe 5 having a capacity of 1 mL to which a nozzle 4 made of a single tube made of stainless steel having an inner diameter of 1 mm is attached, and this syringe is attached to a syringe pump. In FIG. 1, the positions of the nozzle and the conductive substrate are installed in the vertical direction, but the nozzle can be installed in the horizontal direction with respect to the conductive substrate. The electrospray conditions were an applied voltage of 15 kV, a nozzle-conductive substrate distance of 10 cm, and a syringe solution supply flow rate of 5 μL / min.

<Observation / Measurement Method>
As for the spray state, the nozzle tip was irradiated with a 250 W metal halide lamp (LS-M250 manufactured by Megilo Procedure) and observed using a scattered image. In addition, the structure of the fiber was observed using a scanning electron microscope (SEM, SM-200 manufactured by TOPCON). Observation was performed under the condition of an acceleration voltage of 10 kV. As an observation sample, a surface of a polymer fiber coated with gold having a thickness of about 5 nm using a fine coater (JFC-1200 manufactured by JEOL Ltd.) was used. From the obtained secondary electron image, the fiber diameters at 100 arbitrary points on the fiber were measured, and the average fiber diameter was determined.

<Observation and measurement results>
After applying the electric field, spraying of the solution from the nozzle tip was confirmed. FIG. 2 shows a secondary electron image of the polymer electrolyte fiber obtained by SEM observation. The produced polymer electrolyte fiber had an average fiber diameter of 2.5 μm.

  By adding the sol-gel reaction precursor and reaction catalyst to the polymer electrolyte solution, a spray that did not occur with Nafion alone solution was realized, and the polyelectrolyte fiberization in one step using the electrospray deposition method Became possible. Here, it is considered that the addition of the sol-gel reaction precursor and the reaction catalyst contributes to the suppression of the charge relaxation when the electric field is applied.

  If a substance that increases the viscosity of the polymer electrolyte solution with the progress of the reaction is added to the polymer electrolyte solution with high electrical conductivity, the charge relaxation caused by the current generated in the solution when an electric field is applied can be suppressed. One-step polyelectrolyte solution using the deposition method is considered possible.

[Comparative Example 1]

<Preparation of sample solution>
For comparison, a 13.1% by weight Nafion single solution was prepared.

<Production of polymer electrolyte fiber>
The apparatus and production conditions used for production of the polymer electrolyte fiber are the same as those in Example 1.

<Observation / Measurement Method>
The observation of the spray state and the method for observing the polymer electrolyte fiber using the scanning electron microscope and the method for evaluating the fiber diameter are the same as in Example 1.

<Observation and measurement results>
Even when an electric field was applied, spraying of a Nafion single solution could not be confirmed.

[Example 2] (Effect of addition of fiberization accelerator)

<Preparation of sample solution>
Commercially available 20% by mass Nafion solution (DE2021, manufactured by Wako Pure Chemical Industries, Ltd., solvent: 34% by mass water and 44% by mass 1-propanol) and polyvinyl alcohol (PVA, manufactured by Wako Pure Chemical Industries) with an average weight molecular weight of about 80,000 in water. A dissolved 7% by mass aqueous solution is mixed at a weight ratio of 40:20, and tetraethoxysilane (TEOS, a reagent for organic synthesis manufactured by Kanto Chemical) and boric acid (H ₃ BO ₃ , a special grade reagent manufactured by Wako Pure Chemical Industries) are further added. In addition, a sample solution was prepared. This solution has a polyelectrolyte (Nafion) concentration of 13.1% by mass, a fiberization accelerator (PVA) concentration of 2.6% by mass, a sol-gel reaction precursor (TEOS) concentration of 1.6% by mass, a sol gel catalyst (H ₃ BO ₃₎ concentration is 0.2 wt%.

<Production of polymer electrolyte fiber>
The apparatus and production conditions used for production of the polymer electrolyte fiber are the same as those in Example 1.

<Observation / Measurement Method>
The observation of the spray state and the method for observing the polymer electrolyte fiber using the scanning electron microscope and the method for evaluating the fiber diameter are the same as in Example 1.

<Observation and measurement results>
After application of the electric field, a more stable spray was obtained than in Example 1. FIG. 3 shows a secondary electron image of the polymer electrolyte fiber obtained by SEM observation. The average fiber diameter of the polymer electrolyte fiber obtained from the secondary electron image was 430 nm.

  By adding a fiberization accelerator, a sol-gel reaction precursor and a reaction catalyst to the polymer electrolyte solution, stable sprayability was realized, and uniform fibers could be produced. In addition, the fiber diameter was thinner than when no accelerator was added. The reason for this is considered to be an improvement in the spinnability of the polymer electrolyte solution by the addition of a high molecular weight linear polymer.

[Example 3] (Effect of syringe supply flow rate)

<Preparation of sample solution>
Commercially available 20% by mass Nafion solution (DE2021, manufactured by Wako Pure Chemical Industries, Ltd., solvent: 34% by mass water and 44% by mass 1-propanol) and polyvinyl alcohol (PVA, manufactured by Wako Pure Chemical Industries) with an average weight molecular weight of about 80,000 in water. A dissolved 7% by mass aqueous solution is mixed at a weight ratio of 40:20, and tetraethoxysilane (TEOS, a reagent for organic synthesis manufactured by Kanto Chemical) and boric acid (H ₃ BO ₃ , a special grade reagent manufactured by Wako Pure Chemical Industries) are further added. In addition, a sample solution was prepared. Here, as in Example 2, the concentration of the polymer electrolyte (Nafion) was 13.1% by mass, the concentration of the fiberization accelerator (PVA) was 2.6% by mass, and the concentration of the sol-gel reaction precursor (TEOS) Was 1.6 mass%, and the sol-gel reaction catalyst (H ₃ BO ₃ ) concentration was 0.2 mass%.

<Production of polymer electrolyte fiber>
The apparatus used for producing the polyelectrolyte fiber is the same as in Example 1. The electrospray conditions were an applied voltage of 15 kV, a nozzle-conductive substrate distance of 10 cm, and a syringe supply flow rate of 10 μL / min.

<Observation / Measurement Method>
The observation of the spray state and the method for observing the polymer electrolyte fiber using the scanning electron microscope and the method for evaluating the fiber diameter are the same as in Example 1.

<Observation and measurement results>
Under the condition of a syringe supply flow rate of 10 μL / min, the stability of the spray state after application of the electric field decreased. The average fiber diameter of the polymer electrolyte fiber obtained from the secondary electron image was 490 nm.

  Compared to Example 2 (syringe supply flow rate 5 μL / min, average fiber diameter 430 nm), the fiber diameter of the polymer electrolyte fiber slightly increased as the syringe supply flow rate increased. The reason for this may be that the amount of solution spray per unit time increases due to an increase in the syringe supply flow rate.

[Example 4] (Effect of concentration of sol-gel reaction precursor and sol-gel reaction catalyst)

<Preparation of sample solution>
Commercially available 20% by mass Nafion solution (DE2021, manufactured by Wako Pure Chemical Industries, Ltd., solvent: 34% by mass water and 44% by mass 1-propanol) and polyvinyl alcohol (PVA, manufactured by Wako Pure Chemical Industries) with an average weight molecular weight of about 80,000 in water. A dissolved 7% by mass aqueous solution is mixed at a weight ratio of 40:20, and tetraethoxysilane (TEOS, a reagent for organic synthesis manufactured by Kanto Chemical) and boric acid (H ₃ BO ₃ , a special grade reagent manufactured by Wako Pure Chemical Industries) are further added. In addition, a sample solution was prepared. Here, as in Example 2, the polymer electrolyte (Nafion) concentration was fixed at 13.1% by mass, and the fiberization accelerator (PVA) concentration was fixed at 2.6% by mass, and the sol-gel reaction precursor (TEOS) was fixed. ) Was changed to 3.2 mass% and 6.4 mass%. The sol-gel reaction catalyst (H ₃ BO ₃ ) concentration was 0.4% by mass and 0.8% by mass, respectively.

<Production of polymer electrolyte fiber>
The apparatus used for producing the polyelectrolyte fiber is the same as in Example 1. The electrospray conditions were an applied voltage of 15 kV, a nozzle-conductive substrate distance of 10 cm, and a syringe supply flow rate of 10 μL /.

<Observation / Measurement Method>
The observation of the spray state and the method for observing the polymer electrolyte fiber using the scanning electron microscope and the method for evaluating the fiber diameter are the same as in Example 1.

<Observation and measurement results>
After application of the electric field, the same stable spray state as in Example 2 was obtained. 4 and 5 show secondary electron images of polymer electrolyte fibers prepared from a 3.2 mass% TEOS solution and a 6.4 mass% TEOS solution, respectively. The average fiber diameter of the obtained polymer electrolyte fiber was 890 nm for a fiber prepared from a 3.2 mass% TEOS solution and 1.82 μm for a fiber prepared from a 6.4 mass% TEOS solution.

  As the concentration of the sol-gel reaction precursor increased, the fiber diameter of the polymer electrolyte fiber increased. The reason for this is considered that the increase in the molecular weight of inorganic molecules formed in the solution by the sol-gel reaction is promoted as the precursor concentration increases.

[Example 5] (Effect of applied voltage between nozzle and conductive substrate)

<Preparation of sample solution>
Commercially available 20% by mass Nafion solution (DE2021, manufactured by Wako Pure Chemical Industries, Ltd., solvent: 34% by mass water and 44% by mass 1-propanol) and polyvinyl alcohol (PVA, manufactured by Wako Pure Chemical Industries) with an average weight molecular weight of about 80,000 in water. A dissolved 7% by mass aqueous solution is mixed at a weight ratio of 40:20, and tetraethoxysilane (TEOS, a reagent for organic synthesis manufactured by Kanto Chemical) and boric acid (H ₃ BO ₃ , a special grade reagent manufactured by Wako Pure Chemical Industries) are further added. In addition, a sample solution was prepared. Here, as in Example 2, the concentration of the polymer electrolyte (Nafion) was 13.1% by mass, the concentration of the fiberization accelerator (PVA) was 2.6% by mass, and the concentration of the sol-gel reaction precursor (TEOS) Was 1.6 mass%, and the sol-gel reaction catalyst (H ₃ BO ₃ ) concentration was 0.2 mass%.

<Production of polymer electrolyte fiber>
The apparatus used for producing the polyelectrolyte fiber is the same as in Example 1. The electrospray conditions were an applied voltage of 20 kV, a nozzle-conductive substrate distance of 10 cm, and a syringe supply flow rate of 5 μL / min.

<Observation / Measurement Method>
The observation of the spray state and the method for observing the polymer electrolyte fiber using the scanning electron microscope and the method for evaluating the fiber diameter are the same as in Example 1.

<Observation and measurement results>
Even under the condition of an applied voltage of 20 kV, a stable spray state was obtained after application of the electric field. The average fiber diameter of the polymer electrolyte fiber obtained from the secondary electron image was 520 nm.

  Compared to Example 2 (applied voltage 15 kV, average fiber diameter 430 nm), the fiber diameter of the polymer electrolyte fiber increased with the increase of the applied voltage. As a reason for this, it is conceivable that the amount of solution spray per unit time increases due to an increase in charge amount accompanying an increase in voltage.

[Example 6] (Effect of supply flow rate of syringe in coaxial double tube nozzle)

<Preparation of sample solution>
Commercially available 20% by mass Nafion solution (DE2021, manufactured by Wako Pure Chemical Industries, Ltd., solvent: 34% by mass water and 44% by mass 1-propanol) and polyvinyl alcohol (PVA, manufactured by Wako Pure Chemical Industries) with an average weight molecular weight of about 80,000 in water. A dissolved 7% by mass aqueous solution is mixed at a weight ratio of 40:20, and tetraethoxysilane (TEOS, a reagent for organic synthesis manufactured by Kanto Chemical) and boric acid (H ₃ BO ₃ , a special grade reagent manufactured by Wako Pure Chemical Industries) are further added. In addition, a sample solution was prepared. Here, the polymer electrolyte (Nafion) concentration is 12.9% by mass, the fiberization accelerator (PVA) concentration is 2.3% by mass, and the concentration of the sol-gel reaction precursor (TEOS) is 3.2% by mass. The sol-gel reaction catalyst (H ₃ BO ₃ ) concentration was 0.4% by mass, and this solution was used as the outer tube liquid.

<Production of polymer electrolyte fiber>
The apparatus used for producing the polyelectrolyte fiber is almost the same as in Example 1. The difference is that instead of a stainless steel nozzle, a steel coaxial double tube nozzle as shown in Fig. 6 was used, and the inner tube and the outer tube of the double tube nozzle each had a syringe containing a sample solution. It is a point connected to the mounted syringe pump. The above polymer electrolyte solution was supplied to the outer tube, and mineral oil (Aldrich reagent) was supplied to the inner tube, and electrospraying was performed. The electrospray conditions were an applied voltage of 15 kV, a nozzle-conductive substrate distance of 10 cm, an outer tube supply flow rate of 10 μL / min, and an inner tube supply flow rate of 3 μL / min. Spraying was also performed when the supply flow rate of the outer tube was fixed at 10 μL / min and the supply flow rate of the inner tube was changed to 1 μL / min.

<Observation / Measurement Method>
The observation of the spray state and the method for observing the polymer electrolyte fiber using the scanning electron microscope and the method for evaluating the fiber diameter are the same as in Example 1. Moreover, cross-sectional structure observation of the fiber sample produced using the high-resolution transmission type | mold analytical electron microscope (EM-002B / P-20 and STEM system by TOPCON) was also performed. Observation was performed under the condition of an acceleration voltage of 200 kV. As an observation sample, a polymer fiber dyed with an osmic acid solution, embedded in an epoxy resin, and sectioned using an ultramicrotome was used.

<Observation and measurement results>
A stable spray state was obtained after applying the electric field. As a result of spraying, when the outer tube supply flow rate was 10 μL / min and the inner tube supply flow rate was 3 μL / min, core-sheath fibers having the cross-sectional structure shown in FIG. 7 were obtained. The outer black portion is a polyelectrolyte (Nafion) stained with osmic acid, and the inner white portion is mineral oil. The core portion was removed by immersing this fiber in octane for 12 hours to obtain a fiber having a hollow structure shown in FIG. The hollow structure fiber had an outer diameter of 1.51 μm and an inner diameter of 1.22 μm. Further, when the outer tube supply flow rate was 10 μL / min and the inner tube supply flow rate was 1 μL / min, the hollow fiber had an outer diameter of 1.58 μm and an inner diameter of 1.00 μm.

  By using a double tube nozzle, a polymer electrolyte hollow structure fiber could be produced. Further, the inner diameter and wall thickness of the hollow structure fiber changed due to the change in the inner pipe supply flow rate. From this, it is considered that friction and other forces are acting at the interface between the spray from the inner tube and the spray from the outer tube in the coaxial jet immediately after spraying.

It is a figure which shows the apparatus used for the electrospray deposition method. It is a SEM photograph which shows the secondary electron image of the polymer electrolyte fiber after adding a sol-gel precursor and a sol-gel reaction catalyst. It is a SEM photograph which shows the secondary electron image of the polymer electrolyte fiber after adding a fiberization promoter. It is a SEM photograph which shows the secondary electron image of the polymer electrolyte fiber produced from the TEOS3.2 mass% solution. It is a SEM photograph which shows the secondary electron image of the polymer electrolyte fiber produced from the TEOS6.4 mass% solution. It is a figure which shows the coaxial double tube nozzle of the apparatus used for the electrospray deposition method. It is a TEM photograph which shows the core-sheath structure of the polymer electrolyte fiber produced using the coaxial double tube nozzle. It is a SEM photograph which shows the hollow polymer electrolyte fiber which removed the core part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Power supply, 2 ... Syringe pump, 3 ... Conductive substrate, 4 ... Nozzle, 5 ... Syringe, 6 ... Coaxial double pipe nozzle, 7 ... Inner pipe, 8 ... Inner pipe liquid, 9 ... Outer tube, 10 ... Outer tube liquid, 11 ... Coaxial spray jet

Claims (19)

A polyelectrolyte fiber comprising a polyelectrolyte and a sol-gel reaction product. A polymer electrolyte is a polymer compound having a plurality of charged groups,
The charged group is a negatively charged group of a carboxyl group, a phosphate group, a sulfonate group, an amino group, a pyridyl group, an imidazole group, a quaternary ammonium group, a quaternary pyridinium base, a quaternary imidazole group, a positively charged group, or a betaine group. 2. The polymer electrolyte fiber according to claim 1, comprising any one selected from a phosphatidylcholine group and an amphoteric charged group of an amino acid group, or a combination of any two or more thereof. The polymer electrolyte is a copolymer of perfluorosulfonic acid and polytetrafluoroethylene, polystyrene sulfonic acid and its copolymer, sulfonated polysulfone, sulfonated polyetheretherketone, cellulose sulfate, carboxymethylcellulose, polyacrylic acid, polyvinyl Any one or any two selected from pyridine and its quaternized product, polyvinylbenzyltrimethylammonium, polyallylamine, polyethyleneimine and its quaternized product, 2-methacryloyloxyethyl phosphorylcholine homopolymer and copolymer The polymer electrolyte fiber according to claim 1, comprising the above combination. The sol-gel reaction product is a reaction product from a sol-gel reaction precursor,
The sol-gel reaction precursor comprises a metal alkoxide,
The metal of the metal alkoxide is any one selected from Si, Ta, Nb, Ti, Zr, Al, Ge, B, Na, Ga, Ce, V, Ta, P, and Sb, or any two or more A combination of
The alkoxy group of the metal alkoxide is any one selected from an alkoxy group having a carbon number n (n is an integer of 1 to 8), including a methoxy group, an ethoxy group, a propoxy group, and a butoxy group, or any two The polymer electrolyte fiber according to claim 1, comprising a combination of at least species. The polymer electrolyte fiber according to claim 1, wherein the fiber diameter is 5 nm to 50 μm. The polymer electrolyte fiber according to claim 1, wherein the polymer electrolyte is made of a copolymer of perfluorosulfonic acid and polytetrafluoroethylene. The sol-gel reaction product is a reaction product from a sol-gel reaction precursor,
The polymer electrolyte fiber according to claim 6, wherein the sol-gel reaction precursor is made of tetraethoxysilane. The polymer electrolyte fiber according to claim 1, wherein the electrolyte fiber has a hollow structure. The polymer electrolyte fiber according to claim 8, wherein the fiber diameter (outer diameter) is 5 nm to 50 μm. A method for producing a polymer electrolyte fiber, comprising producing a fiber by an electrospray deposition method using a solution containing a polymer electrolyte, a sol-gel reaction precursor, and a sol-gel reaction catalyst. A polymer electrolyte is a polymer compound having a plurality of charged groups,
The charged group is a negatively charged group of a carboxyl group, a phosphate group, a sulfonate group, an amino group, a pyridyl group, an imidazole group, a quaternary ammonium group, a quaternary pyridinium base, a quaternary imidazole group, a positively charged group, or a betaine group. The method for producing a polyelectrolyte fiber according to claim 10, comprising any one selected from the group consisting of phosphatidylcholine groups and amphoteric charged groups of amino acid groups, or a combination of any two or more thereof. The polymer electrolyte is a copolymer of perfluorosulfonic acid and polytetrafluoroethylene, polystyrene sulfonic acid and its copolymer, sulfonated polysulfone, sulfonated polyetheretherketone, cellulose sulfate, carboxymethylcellulose, polyacrylic acid, polyvinyl Any one or any two selected from pyridine and its quaternized product, polyvinylbenzyltrimethylammonium, polyallylamine, polyethyleneimine and its quaternized product, 2-methacryloyloxyethyl phosphorylcholine homopolymer and copolymer It consists of the above combination. The manufacturing method of the polymer electrolyte fiber of Claim 10. The sol-gel reaction precursor consists of a metal alkoxide,
The metal of the metal alkoxide is any one selected from Si, Ta, Nb, Ti, Zr, Al, Ge, B, Na, Ga, Ce, V, Ta, P, and Sb, or any two or more A combination of
The alkoxy group of the metal alkoxide is any one selected from an alkoxy group having a carbon number n (n is an integer of 1 to 8), including a methoxy group, an ethoxy group, a propoxy group, and a butoxy group, or any two The method for producing a polymer electrolyte fiber according to claim 10, comprising a combination of at least species. The sol-gel reaction catalyst consists of an acid or a base,
The acid is any one selected from hydrochloric acid, sulfuric acid, nitric acid, inorganic acid such as boric acid, acetic acid, organic acid such as citric acid, or any combination of two or more thereof.
The method for producing a polymer electrolyte fiber according to claim 10, wherein the base is made of ammonia. The method for producing a polymer electrolyte fiber according to claim 10, wherein the solution contains a fiberization accelerator. 16. The polymer electrolyte fiber according to claim 15, wherein the fiberization accelerator comprises any one selected from polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyhydroxyethyl methacrylate, and polyacrylamide, or a combination of any two or more thereof. Production method. The method for producing a polymer electrolyte fiber according to claim 10, wherein the polymer electrolyte comprises a copolymer of perfluorosulfonic acid and polytetrafluoroethylene. The sol-gel reaction precursor consists of tetraethoxysilane,
The method for producing a polymer electrolyte fiber according to claim 17, wherein the sol-gel reaction catalyst comprises boric acid. The method for producing a polymer electrolyte fiber according to claim 17, wherein the solution contains polyvinyl alcohol.

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