JP4947458B2 - Composite film and manufacturing method thereof - Google Patents

Description

  The present invention relates to a composite film in which boron nitride nanotubes are uniformly dispersed in a polyaniline film and a method for producing the same.

Composite materials composed of two or more different types of substances are discontinuously strengthened to compensate for the weaknesses of the matrix phase (also called the continuous phase) of materials such as ceramics, plastics, and metal materials. It is a material made by dispersing materials.
As an example of the first use of nanotubes as a reinforcing material for polymer composites (polymer composites), composite materials in which carbon nanotubes are added to a solvent-free liquid epoxy resin and cured are known (for example, non-patented) Reference 1).
It is expected that by making nanotubes composite, new electrical properties and optical properties are expressed, and mechanical strength and thermal conductivity are improved (for example, see Non-Patent Document 2).
On the other hand, a composite using a polyaniline film, which is a typical conductive polymer, as a matrix and carbon nanotubes as a reinforcing material is also known. Most of the carbon nanotube / polyaniline composite is manufactured by so-called in-situ polymerization in which polyaniline is polymerized in a dispersion in which carbon nanotubes are dispersed in a solvent (see, for example, Non-Patent Documents 3 to 7). ).

P.M.Ajayan et al., Science 265, 1212, 1994 P.J.F.Harris, International Materials Reviews 49, 31, 2004 R.Sainz et al., Adv.Mater.17, 278, 2005 Murielle Cochet et al., Chem. Commun. 2001, 1450 H. Zengin et al., Adv. Mater. 14, 1480, 2002 H.J.Choi et al., Diam.Relat.Mater.14, 766, 2005 X.Zhang et al., Appl.Phys.A 80, 1813, 2005

  However, a composite film using boron nitride nanotubes having a structure similar to that of carbon nanotubes as a reinforcing material and a polymer as a matrix has not been known yet.

  In view of the above situation, the present invention has an object to provide a novel composite film using boron nitride nanotubes as a reinforcing material and polyaniline as a matrix, and a method for producing the same.

In order to achieve the above object, the composite film of the present invention has boron nitride nanotubes dispersed using boron nitride nanotubes (excluding those functionalized and solubilized) as a reinforcing material and polyaniline as a matrix. It is characterized by.
In the above configuration, the weight ratio of boron nitride nanotubes to polyaniline is preferably in the range of 0.5 to 100 parts by weight of polyaniline with respect to 1 part by weight of boron nitride nanotubes. The polyaniline is preferably in the emeraldine form.
According to this configuration, it is possible to provide a composite film including a polyaniline film in which boron nitride nanotubes are used as a reinforcing material, polyaniline is used as a matrix, and boron nitride nanotubes are uniformly dispersed.

The method for producing a composite film of the present invention includes forming a polyaniline film in which boron nitride nanotubes are dispersed by adding a boron nitride nanotube and emeraldine-type polyaniline to an organic solvent and subjecting the resultant to ultrasonic treatment. Features.
In the above configuration, the boron nitride nanotubes are preferably obtained by allowing ammonia gas to act in a state where magnesium oxide, iron (II) oxide and boron are heated to 1100 to 1700 ° C.
According to this configuration, boron nitride nanotubes and emeraldine-type polyaniline are dispersed in an organic solvent such as N, N-dimethylformamide in a container to form a mixed solution, and this mixed solution is subjected to ultrasonic treatment and then allowed to stand. As a result, a polyaniline film in which boron nitride nanotubes are uniformly dispersed at the bottom of the container is formed. At that time, it is preferable to use a boron nitride nanotube having a high purity, and magnesium oxide, iron (II) oxide and boron are heated to 1100 to 1700 ° C. to generate a vapor of boron oxide. It can be obtained by allowing ammonia gas to act on. On the other hand, polyaniline can be used in the form of emeraldine soluble in organic solvents.

  According to the present invention, a composite film containing boron nitride nanotubes can be provided. Therefore, improvement in physical properties such as elastic modulus, thermal conductivity, heat resistance, and dimensional stability is expected.

First, the composite film of the present invention will be described.
The composite film of the present invention is composed of a polyaniline film in which boron nitride nanotubes are used as a reinforcing material and polyaniline is used as a matrix, and boron nitride nanotubes are uniformly dispersed. Here, the weight ratio of the boron nitride nanotube to the polyaniline is preferably such that the polyaniline contains 0.5 to 100 parts by weight with respect to 1 part by weight of the boron nitride nanotubes. When the weight part of polyaniline is more than 100 parts by weight, the amount of boron nitride nanotubes is too small and the function as a reinforcing material in the composite film is not sufficiently exhibited. On the contrary, when the weight part of polyaniline is less than 0.5 part by weight, the strength of the resulting composite film is brittle, the self-supporting property is poor, and a practical composite film cannot be obtained.

Next, the manufacturing method of this composite film is demonstrated.
The composite film is subjected to ultrasonic treatment by putting a mixture of boron nitride nanotubes, emeraldine-type polyaniline, and an organic solvent such as N, N-dimethylformamide into a container. Then, by allowing to stand, a film in which boron nitride nanotubes are uniformly dispersed is formed on the bottom of the container.
Here, as the boron nitride nanotubes, those produced by various production methods can be used. Magnesium oxide, iron (II) oxide and boron are heated to 1100 to 1700 ° C. to generate boron oxide vapor, It is preferable to use a product obtained by allowing ammonia gas to act on the generated steam from the viewpoint of yield and high purity. At this time, a heating temperature of 1900 ° C. or higher is not preferable because the yield increases but the purity decreases.
On the other hand, it is preferable to use a non-conductive emeraldine type soluble in an organic solvent as polyaniline. At that time, if a commercially available product is used, it is possible to save the trouble of producing the product.

Next, the present invention will be described more specifically with reference to examples.
First, boron nitride nanotubes were produced according to the following procedure.
A mixture of 2 g of boron powder, 1 g of iron oxide (II) (FeO) powder and 1 g of magnesium oxide (MgO) powder was placed in a boron nitride crucible, and this crucible was placed in a vertical high-frequency induction heating furnace. The mixture in the heating furnace was heated to 1400 ° C. to generate boron oxide vapor. While flowing ammonia gas so as to react with the generated vapor, heating was continued at 1400 ° C. for 2 hours to generate boron nitride nanotubes near the wall of the reaction tube in the heating furnace.
The produced boron nitride nanotubes had a diameter of 20 to 50 nm, a tube wall thickness of 6 to 18 nm, and a length of about 10 μm.

Next, 0.2 g of boron nitride nanotubes produced as described above and 0.2 g of emeraldine-based polyaniline (manufactured by Aldrich) were added to 10 cm ³ of N, N-dimethylformamide, and 1.5 g at room temperature. Sonicated for hours.
Then, the film was formed in the bottom of the glass bottle by leaving this liquid mixture still for 12 hours.

  FIG. 1 is a view showing a scanning electron microscope image of the composite film formed in the example. 1 that the composite film formed in the example is a composite film in which boron nitride nanotubes are dispersed and embedded in a matrix of polyaniline. Here, some of the boron nitride nanotubes appeared from the matrix because the composite film was damaged when the composite film was mounted on a silicon wafer.

  In the scanning electron microscope, the composite film formed in the example was irradiated with an electron beam. FIG. 2 is a diagram showing an image of the product after irradiating the composite film formed in the example with an electron beam. From FIG. 2, it can be confirmed that by irradiating the electron beam, polyaniline is decomposed and disappears, and boron nitride nanotubes appear. The morphology of boron nitride nanotubes in the composite film was similar to that of pure boron nitride nanotubes.

  FIG. 3 is a view showing a high-resolution transmission electron microscope image of the composite film formed in the above example. From FIG. 3, it was found that the boron nitride nanotubes were covered with polyaniline. Furthermore, it has been found that boron nitride maintains a completely crystalline structure.

FIG. 4 is a diagram showing X-ray diffraction patterns of the composite film (EB / BNNT), boron nitride nanotubes alone (BNNT) and emeraldine base polyaniline alone (EB) formed in the above example. The vertical axis in the figure is the X-ray diffraction intensity (arbitrary scale), and the horizontal axis is the angle (°), that is, the angle (°) corresponding to twice the incident angle θ of the X-ray to the atomic plane.
As can be seen from FIG. 4, the X-ray diffraction pattern of boron nitride nanotubes alone (BNNT) has peaks at 2θ = 26 °, 41 °, 43 ° and 54 °. The X-ray diffraction pattern of emeraldine base polyaniline alone (EB) has a broad peak centered at 2θ = 19 °. On the other hand, in the X-ray diffraction pattern of the composite film (EB / BNNT) formed in the example, there are peaks derived from single materials of emeraldine base polyaniline and boron nitride nanotube. The half-width of the peak related to emeraldine base polyaniline decreased from 10 ° to 3 ° and became sharp.
From the above, it is confirmed that a composite film in which boron nitride nanotubes are dispersed in polyaniline can be formed.

(Comparative example)
Next, a comparative example is shown.
Carbon nanotubes were used in place of boron nitride nanotubes as the reinforcing material, and carbon nanotubes and emeraldine-based polyaniline were added to N, N-dimethylformamide and sonicated in the same manner as in the examples.
As a result, no film was formed on the bottom of the glass bottle.

  Here, it is noteworthy that the film was not formed even when the same operation was performed using carbon nanotubes instead of boron nitride nanotubes.

  According to the present invention, it is possible to provide a polyaniline composite film in which boron nitride nanotubes are uniformly dispersed. Therefore, application to products requiring high strength, high elastic modulus, high thermal conductivity, etc. is expected. .

It is a figure which shows the scanning electron microscope image of the composite film formed in the Example. It is a figure which shows the image of the product after irradiating an electron beam to the composite film formed in the Example. It is a figure which shows the high-resolution transmission electron microscope image of the composite film formed in the Example. It is a figure which shows each X-ray-diffraction pattern of the composite film formed in the Example, boron nitride nanotube alone, and emeraldine base polyaniline alone.

Claims (5)

Boron nitride nanotubes (excluding those soluble functionalized) and reinforcement, the polyaniline as the matrix, characterized in that the boron nitride nanotubes are dispersed, the composite film.
  The composite film according to claim 1, wherein the weight ratio of the boron nitride nanotubes to the polyaniline is in the range of 0.5 to 100 parts by weight of polyaniline with respect to 1 part by weight of the boron nitride nanotubes.   The composite film according to claim 1, wherein the polyaniline has an emeraldine shape.   A method for producing a composite film, comprising: adding a boron nitride nanotube and an emeraldine-type polyaniline to an organic solvent and subjecting the resultant to ultrasonic treatment to form a polyaniline film in which the boron nitride nanotubes are dispersed. The composite film according to claim 4, wherein the boron nitride nanotubes are obtained by allowing ammonia gas to act in a state where magnesium oxide, iron (II) oxide and boron are heated at 1100 to 1700 ° C. Method.