JP4106432B2 - Organic-inorganic nanocomposite and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention can be applied to optical functional materials, sensor materials, catalyst carriers, adsorbents or inclusion compound host materials, etc., and a zinc hydroxide layer and an organic layer, particularly a surfactant layer, are on the order of nanometers. The present invention relates to a layered organic-inorganic nanocomposite having a structure in which the layers are alternately stacked and a method for producing the same.
[0002]
[Prior art]
In recent years, organic-inorganic composite materials have attracted attention because they can improve the properties of organic materials that are relatively weak to heat, or can impart the functions of organic molecules to inorganic compounds. In particular, organic-inorganic nanocomposites with a composite structure size range on the order of nanometers are composed of molecules, nanometer-sized clusters and fine particles, and molecules and quantum size effects that exist in the nanocomposite. It is expected to exhibit new physical properties due to the above, and is a very promising substance as an optical functional material or a sensor material.
Furthermore, if a layered structure can be introduced into these nanocomposites, new molecules can be intercalated between nanometer-order layers, making it extremely suitable as a catalyst support, an adsorbent, or an inclusion compound host material. It is a promising substance.
[0003]
So far, a method using a reaction between amorphous zinc hydroxide and organic oxychloride or organic carboxylic acid has been known as a method for producing a layered substance having zinc hydroxide as a basic skeleton (for example, non-patent literature). 1).
In addition, as a method for producing a layered material having a zinc-containing double hydroxide and a surfactant as a basic skeleton, a micellar organic anionic surfactant and an uncharged organic layer are provided between layers having a layered double hydroxide as a basic skeleton layer. A method of inserting a substance between layers has also been reported (for example, see Patent Document 1).
However, in the case of these production methods, a step of mixing and reacting hydroxides such as zinc hydroxide and layered double hydroxide, which are the basic skeleton of the layered substance, and organic molecules such as carboxylic acid and anionic surfactant. Before the process for synthesizing these hydroxides is necessary, there is a drawback that the operation becomes extremely complicated. In addition, it has not been possible to produce a layered organic-inorganic nanocomposite composed only of zinc hydroxide and a surfactant.
[0004]
On the other hand, there is also a report of a technique for performing laser ablation using a surfactant aqueous solution. However, in this case, both are methods for adjusting the size of noble metal nanoparticles or obtaining manganese nanowires, and are merely methods for preparing particles of a single metal (see Non-Patent Documents 2 and 3 and Patent Document 2).
[0005]
[Non-Patent Document 1]
Functional material, “Control of layer space and form of layered structure by reaction of zinc hydroxide and organic carboxylic acid” Vol. 12, No. 10, pp. 45-52, 2001 [Non-patent Document 2]
“Full physical preparation of size-selected gold nanoparticles in solution: Laser ablation and laser-induced size control”, Mafune F, Kohno JY, Takeda Y, Kondow T, JOURNAL OF PHYSICAL CHEMISTRY B, 106 (31): 7575-7577 AUG 8 2002.
[Non-Patent Document 3]
“Growth of gold clusters into nanoparticles in a solution following laser-induced fragmentation”, Mafune F, Kohno JY, Takeda Y, Kondow T, JOURNAL OF PHYSICAL CHEMISTRY B, 106 (34): 8555-8561 AUG 29 2002.
[Patent Document 1]
JP-A-6-48742 [Patent Document 2]
Japanese Patent Laid-Open No. 2003-2651
[Problems to be solved by the invention]
The object of the present invention is a zinc hydroxide-surfactant composed of only zinc hydroxide and a surfactant, which has been considered to be difficult to produce by a very simple process, eliminating the above-mentioned problems of the prior art. It is to provide a layered organic-inorganic nanocomposite and a method for producing the same.
[0007]
[Means for Solving the Problems]
As a result of diligent research to achieve the object of the present invention, a strong energy is applied to the surface of zinc metal in an anionic surfactant aqueous solution to release zinc as an atom, ion or cluster in the aqueous solution. The inventors have found that a nanocomposite crystal of zinc hydroxide-organic layer can be obtained by a very simple process.
The present invention
(1) zinc hydroxide layer and wherein _{C n H 2n + 1 O 4} SNa
( N = 12 )
An organic-inorganic nanocomposite characterized in that it has a structure in which layers of sodium dodecyl sulfate are alternately laminated in nanometer order.
Further, the present invention provides a compound of formula C _n H _{2n + 1} O ₄ SNa between zinc hydroxide layers.
( N = 12 )
An organic-inorganic nanocomposite characterized in that sodium dodecyl sulfate has a lamellar structure.
Furthermore, the present invention relates to the formula C _n H _{2n + 1} O ₄ SNa
In a sodium dodecyl sulfate surfactant aqueous solution represented by ( n = 12 ), by applying focused laser beam irradiation energy to the surface of metallic zinc, zinc is released into the aqueous solution as atoms, ions, and clusters. A method for producing an organic-inorganic nanocomposite, characterized in that a zinc hydroxide layer and a layer of sodium dodecyl sulfate are alternately laminated in nanometer order.
[0008]
Furthermore, in the production method of the present invention, the focused laser beam irradiation energy can be 50 mJ / pulse or more .
Furthermore, in the manufacturing method of this invention, the pulse laser beam energy density of 1 J / cm < ² > or more can be provided to the metal zinc target surface .
Moreover, in the manufacturing method of this invention, the density | concentration of the said sodium dodecyl sulfate in aqueous solution can be 0.0001 mol / L or more.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the present invention applies a strong energy to the surface of metallic zinc in an aqueous anionic surfactant solution to release zinc as atoms, ions or clusters in the aqueous solution, and the presence of the anionic surfactant and water. The zinc hydroxide-layered organic-inorganic nanocomposite crystal is produced by a very simple process, but the metal zinc target is focused and irradiated with pulsed laser light in an anionic surfactant solution. When pulse laser ablation is performed by applying energy by the above, a zinc hydroxide-surfactant layered organic-inorganic nanocomposite crystal can be obtained with high efficiency.
In the practice of the present invention, pulse laser ablation is particularly effective. However, for example, a method such as pulse discharge may be applied as long as strong energy capable of releasing zinc as atoms, ions, or clusters can be applied. it can.
[0010]
FIG. 1 shows an apparatus for manufacturing a zinc hydroxide-surfactant layered organic-inorganic nanocomposite (vertical cell system manufacturing apparatus 1-1 and horizontal cell system manufacturing apparatus 1-2). A laser is irradiated from a laser device 2 to a zinc metal plate target 7 placed in a quartz glass cell 5 through a laser light reflecting mirror 3 and a condenser lens 4.
A zinc metal plate having a purity of 98% or more is used for the zinc metal plate target 7. The zinc metal plate target 7 is fixed to the bottom of the quartz glass cell 5 or the shaft 10 on the table 9. An appropriate amount of a surfactant aqueous solution, for example, an anionic surfactant aqueous solution, is added to the quartz glass cell 5. Reference numeral 11 denotes a gear box, and reference numeral 12 denotes a target rotation driving motor.
As the usable surfactant, any surfactant can be used as long as it does not absorb light strongly with respect to the wavelength of the laser beam to be used. For example, alkyl sulfates: C _n H _{2n + 1} O ₄ SNa (n = 10 to 18) can be used.
[0011]
The concentration of the surfactant, for example, the concentration of the anionic surfactant may be 0.0001 mol / L or more, preferably 0.001 mol / L or more and less than the saturation concentration of the surfactant.
The usable laser beam wavelength of the laser device 2 is not required to have strong absorption with respect to the anionic surfactant to be used. For example, the fundamental wave (wavelength: 1064 nm) and second harmonic wave (wavelength) of a pulsed Nd: YAG laser. : 532 nm), third harmonic (wavelength: 355 nm), etc. can be used.
As the energy of the laser light, it is sufficient that the target zinc metal is released as atoms, ions or clusters in the aqueous solution. When a pulse laser is used as an energy source, the laser ablation phenomenon of zinc metal appears. It is enough if there is enough energy.
As energy per pulse, 50 mJ / pulse or more is sufficient. The energy density of the laser beam on the target surface may be 1 J / cm ² or more, preferably ² J / cm ² .
[0012]
Next, actual experimental results will be described. FIG. 2 shows the preparation and analysis procedure. This aqueous solution was prepared by using sodium dodecyl sulfate, which is a cationic surfactant, as a surfactant. In the aqueous solution, sodium dodecyl sulfate is ionized into sodium ion (Na ⁺ ) and dodecyl sulfate cation (C ₁₂ H ₂₅ OSO ₃ ⁻ ). The concentration of sodium dodecyl sulfate was varied in the range of 0.0001 mol / L to 0.1 mol / L.
A zinc plate of 99.9% purity (size 20 mm × 20 mm, thickness 5 mm) was mounted on the apparatus of FIG. 1, and a repetition frequency of 10 Hz was used with the third harmonic (wavelength: 355 nm) of a pulsed Nd: YAG laser. .
[0013]
After adjusting the position of the lens so that the laser beam spot size on the target has a diameter of 1.5 mm with a pulse energy of 100 mJ / pulse, the target is rotated in the sodium dodecyl sulfate aqueous solution via the target rotation drive motor. The pulse laser beam was irradiated for 1 hour.
As a result, zinc was released into the aqueous solution as atoms, ions, and clusters, and reacted immediately in the presence of dodecyl sulfate cation and water to form a zinc hydroxide-surfactant layered organic-inorganic nanocomposite.
[0014]
The obtained solid was washed after centrifugation. Washing and centrifugation were repeated several times to recover a white solid product. The obtained solid product was dried at room temperature in dry air, and then X-ray diffraction analysis, structural analysis by transmission electron microscopy and transmission electron diffraction, energy dispersive X-ray analysis, Fourier transform infrared absorption spectrum measurement and heat The zinc hydroxide-surfactant layered organic-inorganic nanocomposite was characterized by analysis and the like.
[0015]
FIG. 3 shows an X-ray diffraction pattern of the zinc hydroxide-surfactant layered organic-inorganic nanocomposite. A diffraction peak corresponding to the (00l) plane is observed, and it can be seen that the product has a layered structure.
From the peak position of the diffraction peak, it was found that the layer interval was 26.52 mm. The layer spacing can be controlled by the type of anionic surfactant used.
[0016]
In general, an anionic surfactant is composed of an ionized head group and a hydrophobic hydrocarbon chain bonded to the head group, and the longer the chain length of the hydrocarbon chain, the more obtainable is the zinc hydroxide-surfactant. The layer spacing of the layered organic-inorganic nanocomposite tends to increase.
FIG. 4 shows a transmission electron micrograph and a transmission electron diffraction pattern of the zinc hydroxide-surfactant layered organic-inorganic nanocomposite. The product is an octagonal plate-like crystal, and the transmission electron diffraction pattern shows that the zinc hydroxide layer, which is an inorganic layer skeleton, has a β - Zn (OH) ₂ structure having hexagonal crystals.
[0017]
From the Fourier transform infrared absorption spectrum measurement shown in FIG. 5, it was also found that the product clearly contained hydroxyl groups and hydrated water, and dodecyl sulfate groups were inserted between the layers.
Further, from the energy dispersive X-ray analysis, the product does not contain any sodium contained in the anionic surfactant, the Zn to S ratio is 1: 0.35, and the Zn to C ratio is 1: I also found that it was 4.23.
From the results of thermogravimetry shown in FIG. 5, it was also found that the hydroxyl (OH) to H ₂ O ratio was 1: 0.13. The chemical formula of the zinc hydroxide-surfactant layered organic-inorganic nanocomposite formed by laser ablation of zinc in an aqueous sodium dodecyl sulfate solution determined from these results is shown in the following formula.
Zn (OH) _1.66 (C ₁₂ H ₂₅ SO ₄ ) _0.34 · 0.22 H ₂ O
[0018]
Furthermore, by calculating the length of the dodecyl sulfate anion molecule by molecular model simulation and analyzing the arrangement structure of the dodecyl sulfate anion in the layered organic-inorganic nanocomposite, the arrangement structure of the dodecyl sulfate anion in the zinc hydroxide layer is It is considered that a lamellar structure is formed between the zinc hydroxide layers as shown in FIG.
Moreover, when the length of the octadecyl sulfate cation (C ₁₈ H ₃₇ OSO ₃ ⁻ ) is calculated by molecular model simulation and the layer interval of the obtained layered organic-inorganic nanocomposite is estimated, the maximum is 6 nm depending on the inclination of the cation molecule. It was observed that the reaching zinc hydroxide-surfactant layered organic-inorganic nanocomposite was also present.
As described above, when a pulsed laser beam is focused on the surface of metallic zinc in an anionic surfactant aqueous solution and zinc is released into the aqueous solution as atoms, ions, and clusters, organic anions are formed between the layers of zinc hydroxide. A zinc hydroxide-surfactant layered organic-inorganic nanocomposite crystal having a structure inserted with a lamella array can be obtained by a very simple process.
[0019]
【The invention's effect】
In the present invention, zinc hydroxide and organic layers are alternately laminated in nanometer order by applying strong energy to the surface of zinc metal in an aqueous surfactant solution to release zinc into the aqueous solution as atoms, ions or clusters. Zinc hydroxide-surfactant layered organic-inorganic nanocomposite composed of only zinc hydroxide and surfactant, which have been difficult to manufacture in a very simple process. Moreover, it has the outstanding effect that the manufacturing method can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of an apparatus for producing a zinc hydroxide-surfactant layered organic-inorganic nanocomposite.
FIG. 2 is a diagram showing preparation and analysis steps of a zinc hydroxide-surfactant layered organic-inorganic nanocomposite.
FIG. 3 is a diagram showing an X-ray diffraction pattern of a zinc hydroxide-surfactant layered organic-inorganic nanocomposite.
FIG. 4 is a transmission electron micrograph and a transmission electron beam diffraction pattern of a zinc hydroxide-surfactant layered organic-inorganic nanocomposite.
FIG. 5 is a diagram showing a Fourier transform infrared absorption spectrum of a zinc hydroxide-surfactant layered organic-inorganic nanocomposite.
FIG. 6 is a schematic diagram in which a dodecyl sulfate anion forms a lamellar structure in a zinc hydroxide layer.
[Explanation of symbols]
1-1 Vertical Cell System Manufacturing Device 1-2 Horizontal Cell System Manufacturing Device 2 Laser Device 3 Laser Light Reflecting Mirror 4 Condensing Lens 5 Quartz Glass Cell 6 Laser Light 7 Zinc Metal Plate Target 8 Surfactant Aqueous Solution 9 Unit 10 Axis 11 Gearbox 12 Target rotation drive motor

Claims (6)

Zinc hydroxide layer and wherein _{C n H 2n + 1 O 4} SNa
( N = 12 )
An organic-inorganic nanocomposite having a structure in which sodium dodecyl sulfate layers are alternately laminated in nanometer order. Between the layers of zinc hydroxide the formula C _n H _{2n + 1} O ₄ SNa
( N = 12 )
2. The organic-inorganic nanocomposite according to claim 1, wherein sodium dodecyl sulfate has a lamellar arrangement. Formula _{C n H 2n + 1 O 4} SNa
In a sodium dodecyl sulfate surfactant aqueous solution represented by ( n = 12 ), by applying focused laser beam irradiation energy to the surface of metallic zinc, zinc is released into the aqueous solution as atoms, ions, and clusters. A method for producing an organic-inorganic nanocomposite, comprising forming a structure in which zinc hydroxide layers and sodium dodecyl sulfate layers are alternately laminated in nanometer order.   The method for producing an organic-inorganic nanocomposite according to claim 3, wherein the focused irradiation energy of the pulse laser beam is 50 mJ / pulse or more. The method for producing an organic-inorganic nanocomposite according to claim 4, wherein a pulse laser light energy density of 1 J / cm ² or more is imparted to the surface of the metal zinc target. The method for producing an organic-inorganic nanocomposite according to any one of claims 3 to 5, wherein the concentration of the sodium dodecyl sulfate in the aqueous solution is 0.0001 mol / L or more.

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