JP2023120009A - Polymer composite thin film, gas separation device having polymer composite thin film, and method for producing polymer composite thin film - Google Patents

Abstract

To provide a polymer composite thin film which has high functionality and practical structural stability (self-standing property) by being extremely thinly configured due to such a simple constitution that a nano film having flexible functionality and a nano support excellent in mechanical strength are combined (compounded).SOLUTION: A polymer composite thin film has a first layer (reinforcement layer 3) containing a carbon nanotube 5, and a second layer (polymer thin film 2) which is mainly composed of a polymer material and is overlapped so as to be brought into contact with the first layer, wherein the second layer is configured so as to have selective permeability to predetermined gas.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a polymer composite thin film mainly containing a polymer material, particularly a polymer composite thin film having high functionality and significantly improved film strength, a gas separation device comprising the polymer composite thin film, and a high-performance polymer composite thin film. The present invention relates to a method for manufacturing a molecular composite thin film.

As highlighted in the recent IPCC report (IPCC, 2021, AR6 Climate Change 2021: The Physical Science Basis), the increase in atmospheric _CO2 concentration has been pointed out as a factor in climate change and global warming. there is Various mitigation approaches have been proposed to limit anthropogenic emissions of _CO2 , but so-called zero-emission approaches alone are not sufficient to keep global temperature rise below 1.5°C by 2050. It is said that there is In view of this situation, direct air capture (DAC), which directly captures _CO2 from the atmosphere and stores it safely and permanently, such that a net reduction in _CO2 concentration in the air is achieved. Capture) technology is strongly desired.

In DAC technology, methods of mainly absorbing _CO2 in a solvent, adsorbing it on a solid, and separating it with a gas separation membrane are known. It is considered attractive compared to other techniques because it does not involve a separation step.

In relation to gas separation membranes, interest in organic/inorganic nano-membranes has increased in recent years. In the field of inorganic systems, the peculiar physical properties of inorganic carbon compounds such as graphene have attracted worldwide attention, and the international competition for development has intensified at once. This trend has spread to other inorganic materials with nano-thickness, such as _MoS2 , and is now creating a new research field as two-dimensional materials.

On the other hand, in organic systems, there is an enormous amount of research on biological membranes with nano-order thickness from the standpoint of biochemistry and biophysics. Organic nano-films as industrial materials can be expected to have unique characteristics as two-dimensional materials, but in order to promote their practical application, it is essential to realize large areas, no defects, independence, structural stability, etc. .

As an example of organic nano-membrane as an industrial material, there are high expectations for the development of an excellent separation membrane that makes use of the nano-order thickness. In order to maximize the separation function of the separation membrane, it is desirable to make the membrane as thin as possible from the viewpoint of ensuring high permeability. However, in that case, the mechanical strength is lowered and the film becomes fragile and likely to be unusable. That is, there is a trade-off relationship between making the separation membrane thin and mechanical strength from a functional point of view. In order to solve this problem, it is thought to be effective to combine a functional membrane with a thickness as thin as possible with a strong support and framework structure that does not hinder its function.

_With respect to such _gas separation membrane technology, Kim et al. reported that the permeability of ₄ increases in proportion to the amount of open-ended carbon nanotubes in the polymer matrix, making it slightly more permeable to these gases than PDMS (polydimethylsiloxane). (Non-Patent Document 1)

In addition, Nour et al. fabricated PDMS composite materials with different contents of multi-walled carbon nanotubes (MWNTs) as 100-μm-thick membranes and evaluated their gas separation properties _. reported a 94.8% increase in the selectivity of , and that _CH4 is almost completely blocked in membranes with MWNT concentrations above 5%. (Non-Patent Document 2)

Also recently, Ashtiani et al. grew a crystalline metal-organic framework on a free-standing carbon nanotube network, which was then covered with a PDMS layer, resulting in a metal-organic framework (MOF) layer, a CNT layer, and a PDMS layer. have proposed a three-layer composite material with a 3-layer structure, and reported that this three-layer composite material exhibits excellent permselectivity. (Non-Patent Document 3)

Kim, S.; Pechar, T. W.; Marand, E.; Desalination, Poly(imide siloxane) and carbon nanotube mixed matrix membranes for gas separation, Desalination, 2006, 192, 330-339. Nour, M.; Berean, K.; Balendhran, S.; Zhen Ou, J.; Du Plessis, J.; McSweeney, C.; /PDMS composite membranes for H2 and CH4 gas separation, Inter. J. Hydrogen Energy, 2013, 38, 10494-10501. Ashtiani, S.; Sofer, Z.; Pr?a, F.; Friess, K.; Molecular-level fabrication of highly selective composite ZIF-8-CNT-PDMS membranes for effective CO2/N2, CO2/H2 and olefin. /paraffin separations, Separation and Purification Technology, 2021, 274, 119003.

As described above, it is known that the thinner the polymeric material such as PDMS is formed, the better the gas permeability. However, the thinner the polymeric material, the lower the mechanical strength. Here, according to the techniques described in Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3, although carbon nanotubes are employed as functional materials for improving or controlling the gas permeability of membranes, polymer The use of carbon nanotubes as a material for forming thin gas separation membranes composed of the material is not suggested.

In the techniques described in Non-Patent Document 1 and Non-Patent Document 2, a polymer composite thin film is formed by embedding carbon nanotubes in a polymer material. In such a configuration, the carbon nanotubes are considered to form a three-dimensional network in the polymeric material. However, assuming that the carbon nanotubes are uniformly dispersed in the polymer material, the content (concentration) of the carbon nanotubes in the film naturally increases when trying to secure the mechanical strength of the film by means of a three-dimensional network. It will be done. As a result, there is a concern that the gas permeability inherent in the polymer thin film itself may be lowered.

The present invention has been devised to solve such problems of the prior art, and rather than combining (combining) a nanomembrane with flexible functionality and a nanosupport with excellent mechanical strength, A polymer composite thin film having high functionality and practical structural stability (self-standing) due to its simple structure and extremely thin structure, a gas separation device equipped with this polymer composite thin film, and a polymer composite It aims at providing the manufacturing method of a thin film.

The present invention, which has been made to solve the above problems, is a polymer composite thin film containing a polymer material and carbon nanotubes and having selective permeability to a predetermined gas.

This makes it possible to obtain a polymer composite thin film that has both high functionality and high mechanical strength, even if the polymer thin film itself is not self-supporting.

In addition, the present invention comprises a first layer containing carbon nanotubes, and a second layer composed mainly of a polymeric material and superimposed so as to be in contact with the first layer, wherein the second layer is , is a polymeric composite membrane having selective permeability to a given gas.

As a result, even if the polymer thin film itself is not self-supporting, it is possible to obtain a polymer composite thin film that has both high functionality and high mechanical strength by being superimposed on the reinforcing layer.

Further, according to the present invention, the total average thickness of the superimposed first layer and second layer is 1700 nm or less.

Thereby, a polymer composite thin film having extremely high mechanical strength can be obtained.

Further, according to the present invention, the total average thickness of the superimposed first layer and second layer is 120 nm or less.

As a result, it is possible to obtain the polymer composite thin film 1 which is self-supporting and has a CO ₂ permeability exceeding 3000 [GPU].

Further, according to the present invention, the total average film thickness of the superimposed first layer and second layer is 50 nm or less.

As a result, it is possible to obtain the polymer composite thin film 1 which is self-supporting and has a CO ₂ permeability exceeding 20000 [GPU].

Further, according to the present invention, the total average film thickness of the superimposed first layer and second layer is 30 nm or less.

As a result, it is possible to obtain the polymer composite thin film 1 which is self-supporting and has a CO ₂ permeability exceeding 40000 [GPU].

Further, according to the present invention, the first layer includes a first region A1 in which a plurality of the carbon nanotubes exist and a single carbon nanotube in the thickness direction of the first layer in the plane A. and a third region A3 where the carbon nanotube is absent.

As a result, the first layer containing carbon nanotubes can be composed of a tube network, and both the mechanical strength and gas permeability of the polymer composite thin film can be achieved at high levels.

Further, according to the present invention, the second layer selectively permeates carbon dioxide and oxygen.

As a result, by using a gas separator composed of a polymer thin film, oxygen-enriched air with a higher oxygen concentration than normal air, carbon dioxide-enriched air with more carbon dioxide than air, and nitrogen than air It becomes possible to obtain nitrogen-enriched air with a high concentration.

Further, according to the present invention, the carbon nanotubes are dispersed in the polymer material and have selective permeability to a predetermined gas.

As a result, even if the molecular thin film itself is not self-supporting, it is possible to obtain a polymer composite thin film having both high functionality and high mechanical strength by dispersing the carbon nanotubes.

In the present invention, the polymer composite thin film has a first region A1 in which a plurality of the carbon nanotubes are present and a single carbon nanotube in the thickness direction of the polymer composite thin film in the plane A. and a third region A3 where the carbon nanotube is absent.

As a result, the tube network of carbon nanotubes formed in the polymer thin film makes it possible to achieve both high levels of mechanical strength and gas permeability of the polymer composite thin film.

Further, in the present invention, when the area of the first region A1 is S1, the area of the second region A2 is S2, and the area of the third region A3 is S3, the first layer is S1 <S2<S3.

As a result, the tube network composed of carbon nanotubes can be formed extremely sparsely, and both the mechanical strength and the gas permeability of the polymer composite thin film can be achieved at high levels.

Also, in the present invention, polysiloxane is mainly used as the polymer material.

This makes it possible to manufacture a polymer composite thin film at a lower cost using commonly available materials.

Further, the present invention is a gas separation device comprising the polymer composite thin film and a gas supply section for supplying gas to the polymer composite thin film.

This makes it possible to obtain oxygen-enriched air, carbon dioxide-enriched air, and nitrogen-enriched air using the polymer composite thin film 1 .

Further, the present invention includes the polymer composite thin film, and a gas supply unit that supplies a gas to the polymer composite thin film, and the gas supply unit supplies the second layer and the first layer. It is a gas separator that supplies gas so that the gas permeates in the order of.

This makes it possible to obtain oxygen-enriched air, carbon dioxide-enriched air, and nitrogen-enriched air with high efficiency using the polymer composite thin film 1 .

Further, the present invention provides a first step of preparing a carbon nanotube aqueous dispersion containing carbon nanotubes and a polymer material-containing solution containing a polymer material, and forming the sacrificial layer on a base material on which a sacrificial layer is formed. a second step of forming a first layer mainly composed of the carbon nanotubes by applying and drying the carbon nanotube aqueous dispersion so as to cover the layer; A third step of forming a second layer by applying and curing a polymer material-containing solution, and dissolving the sacrificial layer to form a polymer composite thin film composed of the first layer and the second layer. and a fourth step of peeling from the substrate.

As a result, it is possible to produce a polymer composite thin film that is self-supporting and has high functionality.

Further, in the present invention, the first step includes a filtering step of filtering the carbon nanotube aqueous dispersion to generate a post-filtration dispersion, and the filtering step removes the carbon nanotubes from the carbon nanotube aqueous dispersion. It removes at least part of the aggregates and limits the size of the carbon nanotubes contained in the post-filtration dispersion.

As a result, defects in the polymer composite thin film 1 can be significantly suppressed, and it is possible to manufacture a polymer composite thin film having self-supporting properties and high functionality.

Further, the present invention provides a first step of diluting a carbon nanotube aqueous dispersion containing carbon nanotubes with a first solvent to prepare a water-first solvent dispersion, and adding a polymer material to the water-first solvent dispersion. After adding and kneading the main agent, a second step of adding a curing agent for curing the polymer material and kneading it to obtain a mixed solution, and diluting the mixed solution with a second solvent and after dilution a third step of obtaining a mixed solution; and a fourth step of forming a polymer composite thin film by applying and curing the diluted mixed solution so as to coat the sacrificial layer on the substrate on which the sacrificial layer is formed. and a fifth step of dissolving the sacrificial layer and peeling the polymer composite thin film from the substrate.

As a result, it is possible to produce a polymer composite thin film that is self-supporting and has high functionality.

Also, in the present invention, ethanol is used as the first solvent, and hexane is used as the second solvent.

This makes it possible to produce polymer composite thin films using readily available solvents.

As described above, according to the present invention, a polymer composite thin film having high functionality and practical structural stability (self-standing) due to its extremely thin structure, and a gas separation device equipped with this polymer composite thin film are provided. can be obtained.

(a) and (b) are explanatory views showing the configuration of the polymer composite thin film 1 according to the first embodiment and the gas separator 6 composed of the polymer composite thin film 1. SEM image of cross section of 0.5 v/v% PDMS/0.1 wt% CNT film SEM image of cross section of 0.5v/v% PDMS/0.02wt% CNT film SEM image of cross section of 0.5v/v% PDMS/0.01wt% CNT film SEM image of cross section of 0.12 v/v% PDMS (x 2)/0.005 wt% CNT film SEM image of cross section of 0.12 v/v% PDMS (x 2)/0.001 wt% CNT film (a) and (b) are SEM images showing the residue on the polycarbonate filter after the first suction filtration. SEM image of reinforcing layer 3 formed on sacrificial layer SEM image of cross section of 0.12 v/v% PDMS (×2)/0.005 wt% CNT film after filtration SEM image of cross section of 10v/v% PDMS/0.01wt% CNT film SEM image of cross section of 5v/v% PDMS/0.01wt% CNT film SEM image of cross section of 3 v/v% PDMS/0.01 wt% CNT film SEM image of cross section of second 3 v/v % PDMS/0.01 wt % CNT film (a) and (b) are photographs showing the deflection of the films obtained in Comparative Example 2 and Example 11 when the same load was applied. Graph showing the relationship between stress (σ) and deflection (ε) in the films obtained in Comparative Example 2 and Example 11 Explanatory drawing showing the structure of the polymer composite thin film 1 according to the second embodiment and the gas separator 6 composed of the polymer composite thin film 1 SEM image of cross section of 2 v/v% PDMS-CNT film SEM image of cross section of 0.5v/v% PDMS-CNT film Explanatory drawing showing the configuration of a gas separation device 10 to which the gas separator 6 is applied

(First embodiment)
FIGS. 1(a) and 1(b) are explanatory diagrams showing the configuration of a polymer composite thin film 1 according to the present invention and a gas separator 6 composed of the polymer composite thin film 1. FIG. A first embodiment of the present invention will be described below with reference to FIG.

The gas separator 6 is composed of the polymer composite thin film 1 and the support 4 . As shown in FIG. 1, the polymer composite thin film 1 includes a reinforcement layer 3 (first layer) containing carbon nanotubes 5 and a polymer layer mainly composed of a polymer material and superimposed so as to be in contact with the reinforcement layer 3 . and a thin film 2 (second layer). That is, the carbon nanotubes 5 are locally (unevenly distributed) arranged in the polymer composite thin film 1 . And the second layer has selective permeability to a predetermined gas. A gas separator 6 is constructed by stacking the polymer composite thin film 1 on the support 4 .

As will be described later, the polymer composite thin film 1 is formed by forming the reinforcing layer 3 as the first layer and then forming the polymer thin film 2 as the second layer so as to cover the reinforcing layer 3. , the reinforcing layer 3 contains a mixture of the carbon nanotubes 5 and the polymeric material (that is, the reinforcing layer 3 contains at least the carbon nanotubes 5).

From this point of view, the polymer composite thin film 1 according to the present invention has a configuration in which the polymer thin film 2 includes the carbon nanotubes 5, or the polymer composite thin film 1 includes the polymer thin film 2 and the carbon nanotubes 5. It can also be said to have a compounded configuration. The carbon nanotube 5 has a high mechanical strength as a material, and when combined with the polymer thin film 2, the polymer composite thin film 1 exhibits extremely high mechanical strength.

In the first embodiment, either a single-walled carbon nanotube (SWNT) or a multi-walled carbon nanotube (MWNT) may be used as the carbon nanotube 5 . The carbon nanotubes 5 can form a network of tubes due to their high aspect ratio (0.5 to 3 nm in diameter and ~10 µm in length for SWNTs, and 5 to 100 nm in diameter and ~20 µm in length for MWNTs). , its mechanical properties are obtained by a combination of stiffness, strength and tensile strength.

As a material for forming the polymer thin film 2, for example, vinyl polymer, polysiloxane, and crosslinkable polymer can be preferably used. Here, vinyl polymers and polysiloxanes are considered to be difficult to ensure mechanical strength (self-supporting property) with a film thickness (e.g., 100 nm or less) capable of effectively exhibiting functionality such as gas separation. ing. In this case, by combining the polymer thin film 2 mainly composed of vinyl polymer or polysiloxane with the carbon nanotubes 5, it is possible to achieve both functionality and independence of the polymer composite thin film 1. .

When the polymer thin film 2 is mainly made of vinyl polymer or mainly polysiloxane, the gas separator 6 preferably has the structure shown in FIG. A reinforcing layer 3 is provided between the body 4 and the polymer thin film 2 so as to adhere to at least the polymer thin film 2 . Alternatively, as shown in FIG. 1(b), a configuration may be adopted in which a polymer thin film 2 is formed between the support 4 and the reinforcing layer 3 so as to be in close contact with at least the reinforcing layer 3. FIG.

That is, the gas separator 6 is obtained by superimposing the reinforcing layer 3 and the polymer thin film 2 on the support 4 so as to be in close contact with the polymer thin film 2 . 1(a) is selected by bringing the reinforcing layer 3 into contact with the support 4 in the fourth step (transfer step) of the manufacturing process of the gas separator 6, which will be described later. By contacting the molecular thin film 2, the configuration of FIG. 1(b) can be selected.

On the other hand, the crosslinkable polymer is said to be self-sustaining as a material even at a film thickness (for example, 100 nm or less) capable of effectively exhibiting its functionality. Here, a crosslinkable polymer (crosslinked polymer) refers to a polymer having a three-dimensional network structure (crosslinked structure) by chemically bonding a plurality of linear polymer chains. Contains epoxy resins in which epoxy groups and amino groups as are crosslinked by a chemical reaction.

As for the epoxy resin, an example of a self-supporting polymer thin film having a thickness of 20 nm is described in A Large, Freestanding, 20 nm Thick Nanomembrane Based on an Epoxy Resin, H. Watanabe T. Kunitake, ADVANCED MATERIALS Volume 19, Issue 7, Pages 909-912, 2007
(https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.200601630)
is published in

Of course, the polymer thin film 2 mainly composed of the crosslinkable polymer and the reinforcing layer 3 containing the carbon nanotubes 5 may be combined to form the polymer composite thin film 1. Together with this, it becomes possible to ensure even stronger mechanical strength.

In the first embodiment, the thickness of the polymer composite thin film 1, that is, the average thickness of the sum of the thicknesses of the superimposed reinforcing layer 3 and polymer thin film 2 is set to 1700 nm or less. When the polymer composite thin film 1 is required to have particularly high mechanical strength, such as for industrial plant applications, the average film thickness of the polymer composite thin film 1 should be about 1700 nm to 1000 nm (larger than 1000 nm and 1700 nm or less). By doing so, the polymer composite thin film 1 having extremely high mechanical strength can be obtained. Further, based on which of gas permeability and mechanical strength should be prioritized, the average film thickness of the polymer composite thin film 1 can be appropriately selected in the range of 1000 nm to 120 nm (larger than 120 nm and 1000 nm or less). .

In order to achieve both gas permeability and mechanical strength in a well-balanced manner, the average film thickness of the polymer composite thin film 1 should be 120 nm or less. By setting the average thickness to 120 nm to 50 nm (larger than 50 nm and 120 nm or less), it is possible to obtain the polymer composite thin film 1 that is self-supporting and has a CO ₂ permeability exceeding 3000 [GPU].

When high gas permeability is required, the average film thickness of the polymer composite thin film 1 is preferably 50 nm or less. By setting the average thickness to 50 nm to 30 nm (larger than 30 nm and 50 nm or less), it is possible to obtain the polymer composite thin film 1 which is self-supporting and has a CO ₂ permeability exceeding 20000 [GPU].

If higher gas permeability is required, the average film thickness of the polymer composite thin film 1 is preferably 30 nm or less. By setting the average film thickness to 30 nm or less (27 nm or more), it is possible to obtain the polymer composite thin film 1 which is self-supporting and has a CO ₂ permeability exceeding 40000 [GPU].

The carbon nanotube 5 has a diameter smaller than the film thickness of the polymer composite thin film 1 . By selecting the carbon nanotube 5 whose diameter is smaller than the film thickness of the polymer composite thin film 1, the functionality of the polymer composite thin film 1 can be fully exhibited. Conversely, if carbon nanotubes 5 having a diameter equal to or larger than the film thickness of the polymer composite thin film 1 are mixed in the polymer composite thin film 1, the polymer thin film 2 is likely to have defects, etc., and the functionality cannot be sufficiently exhibited. becomes difficult.

In FIG. 1, the carbon nanotubes 5 having the same fiber length are shown aligned in a specific direction, but this is merely a schematic illustration. The length of the carbon nanotubes 5 varies (up to 20 μm), and the carbon nanotubes 5 are oriented in all directions and are included in the polymer composite thin film 1 in an entangled state (tube network). However, as will be described in detail later in Examples, the distribution of the tube network in the reinforcing layer 3 is restricted (controlled) so that the density of the carbon nanotubes 5 is sparse, and as a result, the polymer composite thin film 1 is formed. Greatly enhances functionality.

Here, the support 4 is made of, for example, polyacrylonitrile (hereinafter sometimes referred to as "PAN"). PAN is a plastic whose main component is a base polymer containing 50% or more acrylonitrile, and has characteristics such as gas barrier properties and high rigidity. On the other hand, by applying tension to a membrane composed of PAN (PAN membrane), it is possible to obtain a porous PAN membrane having countless fine voids and high gas permeability. In the first embodiment, a porous PAN membrane (PAN support membrane) having high gas permeability is used as the support 4 .

Now, when the gas to be separated (the gas containing the gas molecules to be separated) is supplied from the side of the support 4, the polymer composite thin film 1 and the support 4 may separate from each other. , (b), it is preferable to supply the gas to be separated from the polymer composite thin film 1 side of the gas separator 6 .

The outline of the manufacturing process of the polymer composite thin film 1 and the gas separator 6 provided with the polymer composite thin film 1 will be described below.
<First step>
In manufacturing the polymer composite thin film 1, the carbon nanotubes 5 (hereinafter sometimes referred to as "CNT") are dispersed in pure water in advance, and a carbon nanotube aqueous dispersion (hereinafter referred to as "CNT aqueous dispersion") is prepared. ) should be prepared. As the CNT, for example, TUBALL BATT H2O (TUBALL is a registered trademark) manufactured by OCSiAl can be preferably used. The CNT aqueous dispersion is used in the second step, which will be described later. Since the carbon nanotubes 5 are usually difficult to disperse in water, a so-called dispersant is used when preparing the CNT aqueous dispersion.

Examples of dispersants include N-iodosuccinimide (NIS), sodium dodecylbenzene sulfate (SDBS), sodium cholate (SC), sodium deoxycholate (DOC), polyvinylpyrrolidone (PVP), and carboxymethylcellulose (CMC). Although it can be used, it is preferable to use SDBS or PVP from the viewpoint of the curability of the polymeric material (here, PDMS) when superimposed on the reinforcing layer 3 and the dispersibility of the carbon nanotubes 5 .

The first step preferably includes a filtration step of filtering the aqueous CNT dispersion to produce a post-filtration dispersion. This filtration step removes at least a portion of the aggregates of the carbon nanotubes 5 from the aqueous CNT dispersion and substantially limits the size of the carbon nanotubes 5 contained in the post-filtration dispersion. That is, by adding a filtration step, the size or size distribution of the carbon nanotubes 5 contained in the post-filtration dispersion can be controlled.

Of course, not all the aggregates contained in the CNT aqueous dispersion are removed by the filtration process, but by using the post-filtration dispersion, the defects in the polymer composite thin film 1 are greatly suppressed, and the selection against gas is reduced. Permeability (here O ₂ /N ₂ selectivity, CO ₂ /N ₂ selectivity) is improved (see Example 6 below). It was also found that the aqueous CNT dispersion that has undergone the filtration process is less prone to aggregation and the like over time.

In the first step, a polymeric material (precursor) is dissolved in a solvent such as hexane, which has low water solubility, to prepare a polymeric material-containing solution. The polymeric material-containing solution is used in the third step, which will be described later.

<Second step>
Next, a CNT aqueous dispersion is applied onto a glass substrate (hereinafter sometimes referred to as a “base material”) on which a sacrificial layer is formed so as to cover the sacrificial layer, and then dried to form a substrate mainly composed of carbon. A reinforcing layer 3 (first layer) composed of nanotubes 5 is formed.

A spin coating method or a dip coating method can be used to apply the CNT aqueous dispersion onto the substrate. In particular, by employing the spin coating method, a strong external force acts on the carbon nanotubes 5 contained in the CNT aqueous dispersion, and the substantially rigid carbon nanotubes 5 form a three-dimensional tube network, that is, in the thickness direction of the film. Not configurable. As a result, the carbon nanotubes 5 are swept away by water and arranged on a plane, forming a two-dimensional tube network.

<Third step>
A polymeric material-containing solution is applied and cured to form a polymeric thin film 2 (second layer) so as to further cover the reinforcing layer 3 formed on the substrate. At this time, the polymer material-containing solution completely covers the carbon nanotubes 5 forming the reinforcing layer 3, so that the reinforcing layer 3 forms a layer in which the carbon nanotubes 5 and the polymer material are mixed. Then, the polymer thin film 2 is superimposed (combined or practically integrated) with the reinforcing layer 3, so that even if the polymer thin film 2 is extremely thin and cannot stand on its own, 1 can be configured.

<Fourth step>
The sacrificial layer is dissolved in a predetermined solvent, and the polymer composite thin film 1 composed of the reinforcing layer 3 and the polymer thin film 2 is peeled off from the substrate. Thereafter, the peeled polymer composite thin film 1 is transferred to the support 4 to obtain the gas separator 6 .

Thus, in the method for producing the polymer composite thin film 1 of the first embodiment, the first step of preparing the carbon nanotube aqueous dispersion containing the carbon nanotubes 5 and preparing the polymer material-containing solution containing the polymer material. Then, the carbon nanotube aqueous dispersion is applied and dried on the substrate on which the sacrificial layer is formed so as to cover the sacrificial layer, thereby forming a first layer (reinforcing layer 3) mainly composed of carbon nanotubes 5. a third step of forming a second layer (polymer thin film 2) by applying and curing a polymeric material-containing solution so as to cover the first layer; and dissolving the sacrificial layer. , and a fourth step of peeling the polymer composite thin film 1 composed of the first layer and the second layer from the base material, and the first step includes filtering the carbon nanotube aqueous dispersion after filtration. A filtration step is included to produce a dispersion.

The filtration step included in the first step removes aggregates of the carbon nanotubes 5 from the carbon nanotube aqueous dispersion, and limits the size or size distribution of the carbon nanotubes 5 contained in the post-filtration dispersion.

Examples of the polymer composite thin film 1 according to the first embodiment will be described below.

An aqueous CNT dispersion was prepared by adding a dispersant to 0.2% by weight of CNT, and this was diluted with ion-exchanged water to prepare a 0.1% by weight CNT aqueous dispersion. This was subjected to ultrasonic treatment and centrifugation treatment to obtain a supernatant (hereinafter sometimes referred to as "0.1 wt% CNT"). However, since the carbon nanotubes 5 are hardly sedimented by the centrifugation treatment, the centrifugation treatment may be omitted. (Same for other examples)

Separately, polydimethylsiloxane (PDMS) resin (manufactured by Dow Corning Toray Co., Ltd., SYLGARD184 (SYLGARD is a registered trademark)), which is one of silicone polymers, is mixed with a main agent and a curing agent at a ratio of 10:1, and hexane is added to the mixture. A 10% by volume PDMS/hexane solution was prepared. A predetermined amount of hexane was added to this to prepare a 0.5% by volume PDMS/hexane solution (hereinafter sometimes referred to as "0.5v/v% PDMS"), which was used in subsequent operations. .

Prior to the preparation of the polymer composite thin film 1, first, a polyhydroxystyrene (PHS)/ethanol solution (15% by weight) was spin-coated (3000 rpm/1 minute) on the substrate to form a PHS layer (sacrificial layer), and then dried. and further hydrophilized the surface of the base material. Furthermore, 0.1 wt % CNTs produced by the above-described operation were applied onto this base material by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

0.5 v/v % PDMS was then spin-coated to cover the reinforcing layer 3, after which the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed.

After allowing to cool to room temperature, this base material was immersed in ethanol, and the polymer composite thin film 1 in which the reinforcing layer 3 and the polymer thin film 2 were superimposed was peeled off from the base material. Thereafter, the peeled polymer composite thin film 1 was transferred to the support 4 to prepare the gas separator 6 . Hereinafter, the polymer composite thin film 1 produced in Example 1 will be referred to as "0.5 v/v % PDMS/0.1 wt % CNT film".

FIG. 2 is a cross-sectional SEM image of a 0.5 v/v % PDMS/0.1 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 120 nm±30 nm (average film thickness thickness (based on multi-point measurement; hereinafter the same)=120 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 3353 [GPU] and the N ₂ permeability was 645 [GPU].

An aqueous CNT dispersion was prepared by adding a dispersant to 0.2% by weight of CNT, and this was diluted with ion-exchanged water to prepare a 0.02% by weight CNT aqueous dispersion. This was subjected to ultrasonic treatment and centrifugation treatment to obtain a supernatant liquid (hereinafter sometimes referred to as "0.02 wt% CNT").

A polymer composite thin film 1 and a gas separator 6 were produced under the same conditions as in Example 1, except that 0.02 wt % CNT was used. Hereinafter, the polymer composite thin film 1 produced in Example 2 is referred to as "0.5 v/v % PDMS/0.02 wt % CNT film".

FIG. 3 is a cross-sectional SEM image of a 0.5 v/v % PDMS/0.02 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 67 nm±5 nm (average film thickness thickness = 67 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 13019 [GPU] and the N ₂ permeability was 1759 [GPU].

An aqueous CNT dispersion was prepared by adding a dispersant to 0.2% by weight of CNT, and this was diluted with ion-exchanged water to prepare a 0.01% by weight CNT aqueous dispersion. This was subjected to ultrasonic treatment and centrifugation treatment to obtain a supernatant (hereinafter sometimes referred to as "0.01 wt% CNT").

A polymer composite thin film 1 and a gas separator 6 were produced under the same conditions as in Example 1, except that 0.01 wt % CNT was used. Hereinafter, the polymer composite thin film 1 produced in Example 3 will be referred to as "0.5 v/v % PDMS/0.01 wt % CNT film".

FIG. 4 is a cross-sectional SEM image of a 0.5 v/v % PDMS/0.01 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 48 nm±8 nm (average film thickness thickness = 48 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 24094 [GPU] and the N ₂ permeability was 2930 [GPU].

An aqueous CNT dispersion was prepared by adding a dispersant to 0.2% by weight of CNT, and this was diluted with ion-exchanged water to prepare a 0.005% by weight CNT aqueous dispersion. This was subjected to ultrasonic treatment and centrifugation treatment to obtain a supernatant (hereinafter sometimes referred to as "0.005 wt% CNT").

Separately, a main agent of PDMS and a curing agent were mixed at a ratio of 10:1, and hexane was added thereto to prepare a 10% by volume PDMS/hexane solution. A predetermined amount of hexane was added to this to prepare a 0.12 volume % PDMS/hexane solution (hereinafter sometimes referred to as "0.12 v/v % PDMS").

As in Example 1 and the like, a sacrificial layer was formed on the base material, and 0.005 wt % CNTs produced by the above operation were applied thereon by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

Next, 0.12 v/v% PDMS was formed into a film by spin coating so as to cover the reinforcing layer 3, and then the substrate was heated to cure the PDMS. A film of 0.12 v/v% PDMS was further formed on the cured PDMS by spin coating, and then the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed. As described above, in Example 4, the polymer thin film 2 is formed by coating and drying 0.12 v/v % PDMS twice.

After standing to cool to room temperature, this base material is immersed in ethanol to dissolve the sacrificial layer, and the polymer composite thin film 1 in which the reinforcing layer 3 and the polymer thin film 2 are superimposed is peeled off from the base material, and the gas separator 6 is obtained. It was created. Hereinafter, the polymer composite thin film 1 produced in Example 4 is referred to as "0.12 v/v% PDMS (x2)/0.005 wt% CNT film".

FIG. 5 is a cross-sectional SEM image of a 0.12 v/v % PDMS (×2)/0.005 wt % CNT film. However, in FIG. 5, the gas separator 6 as an object is slightly inclined, and the surface of the polymer thin film 2 is photographed in the upper part. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 50 nm±10 nm (average film thickness thickness = 50 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 10741 [GPU], the N ₂ permeability was 1634 [GPU], and the O ₂ permeability was 2714 [GPU]. Met.

An aqueous CNT dispersion was prepared by adding a dispersant to 0.2% by weight of CNT, and this was diluted with ion-exchanged water to prepare a 0.001% by weight CNT aqueous dispersion. This was subjected to ultrasonic treatment and centrifugation treatment to obtain a supernatant (hereinafter sometimes referred to as "0.001 wt% CNT").

Polymer composite thin film 1 and gas separator 6 were produced under the same conditions as in Example 4, except that 0.001 wt % CNT was used. Also in Example 5, the polymer thin film 2 is formed by coating and drying 0.12 v/v % PDMS twice. Hereinafter, the polymer composite thin film 1 produced in Example 5 is referred to as "0.12 v/v% PDMS (x2)/0.001 wt% CNT film".

FIG. 6 is a cross-sectional SEM image of a 0.12 v/v % PDMS (×2)/0.001 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 45 nm±10 nm (average film thickness thickness = 45 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 27990 [GPU], the N ₂ permeability was 3307 [GPU], and the O ₂ permeability was 6639 [GPU]. Met.

0.01 wt% CNT was obtained in the same manner as in Example 3. This 0.01 wt% CNT was subjected to repeated suction filtration using a polycarbonate filter. Filtered 0.01 wt% CNT is diluted by adding ion-exchanged water, and then subjected to ultrasonic treatment and filtration to obtain a post-filtration dispersion (hereinafter sometimes referred to as "post-filtration 0.005 wt% CNT". ) was obtained.

Thus, in Example 6, the step of preparing the aqueous CNT dispersion (first step) includes a filtration step of filtering the dispersion to produce a post-filtration dispersion.

FIGS. 7(a) and (b) are SEM images showing residues on the polycarbonate filter after the first suction filtration. In the polycarbonate filter after the first suction filtration, there are huge bundles 7 of carbon nanotubes 5 (with a width of several hundred nm; see FIG. 7(a)) and aggregates 8 (with a diameter of about several hundred nm) that do not pass through the filter. (see FIG. 7(b)). However, almost no such residue remained when the second and third filtrations were carried out.

Next, in the same manner as in Example 1 and the like, a sacrificial layer was formed on the base material, and 0.005 wt % CNTs after filtering produced by the above operation were applied thereon by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

FIG. 8 is an SEM image of the reinforcement layer 3 formed on the sacrificial layer. FIG. 8 shows the state before the polymer thin film 2 is formed on the reinforcing layer 3, and shows the state of the carbon nanotubes 5 constituting the reinforcing layer 3. FIG.

According to FIG. 8, in Example 6, the carbon nanotubes 5 form an extremely sparse tube network. That is, this sparse tube network has a first region A1 in which a plurality of carbon nanotubes 5 exist and a second region A1 in which a single carbon nanotube 5 exists in the thickness direction of the reinforcing layer 3 in the plane A. A region A2 and a third region A3 in which the carbon nanotubes 5 are absent are mixed. This can also be rephrased as having a region where the plurality of carbon nanotubes 5 do not overlap each other in the thickness direction of the reinforcing layer 3 in a part of the plane that the reinforcing layer 3 forms. In addition, in FIG. 8, the first area A1, the second area A2, and the third area A3 show only representative parts that are relatively easy to illustrate.

Further, in the reinforcing layer 3, when the area of the first region A1 is S1, the area of the second region A2 is S2, and the area of the third region A3 is S3, the reinforcing layer 3 satisfies S1<S2<S3 is configured to be Assuming that the proportion of S3 in plane A is the porosity, it can be seen from FIG. 8 that the porosity clearly exceeds 90%.

In addition, in the first region A1 where a plurality of carbon nanotubes 5 are present, it is observed that two carbon nanotubes 5 (two layers) overlap in the thickness direction of the reinforcing layer 3, but three (three layers) A region where the above carbon nanotubes 5 overlap is not found. That is, in Example 6, the reinforcing layer 3 was mainly composed of a single layer (single) or two layers (two layers) of the carbon nanotubes 5 stacked in the thickness direction of the reinforcing layer 3 at the portion where the carbon nanotubes 5 exist. It can be said that it has a configuration.

Now, the filtering process increases the probability of removing (long) carbon nanotubes 5 that are at least larger than the pore size of the polycarbonate filter (here, 5 μm). Furthermore, it can be said that the residue shown in FIG. 7 constitutes an extremely dense tube network. limit the size of

That is, the filtering process can control the size and size distribution of the carbon nanotubes 5 contained in the filtered dispersion. Furthermore, it is clear that the weight percent of CNTs contained in the aqueous CNT dispersion of the post-filtration dispersion is reduced by the filtration process compared to that before filtration. This provides a very sparse network of tubes as shown in FIG.

As described above, SWNTs have a diameter of 0.5 to 3 nm and a length of up to 10 μm, and MWNTs have a diameter of 5 to 100 nm and a length of up to 20 μm. Commercially available carbon nanotubes 5 usually contain a mixture of SWNTs and MWNTs, but it is believed that the filtration process increases the proportion of smaller size SWNTs in the dispersion after filtration.

Next, 0.12 v/v% PDMS was formed into a film by spin coating so as to cover the reinforcing layer 3, and then the substrate was heated to cure the PDMS. A film of 0.12 v/v% PDMS was further formed on the cured PDMS by spin coating, and then the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed. Thus, in Example 6, similarly to Example 4, the polymer thin film 2 is formed by applying and drying 0.12 v/v % PDMS twice.

After standing to cool to room temperature, this base material is immersed in ethanol to dissolve the sacrificial layer, and the polymer composite thin film 1 in which the reinforcing layer 3 and the polymer thin film 2 are superimposed is peeled off from the base material, and the gas separator 6 is obtained. It was created. Hereinafter, the polymer composite thin film 1 prepared in Example 6 is referred to as "0.12 v/v % PDMS (x2)/0.005 wt % CNT film after filtration".

FIG. 9 is a cross-sectional SEM image of a 0.12 v/v % PDMS (×2)/0.005 wt % CNT film after filtration. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 27 nm ± 8 nm (average film thickness thickness = 27 nm). In addition, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 42463 [GPU], the N ₂ permeability was 4260 [GPU], and the O ₂ permeability was 9463 [GPU]. Met.

0.01 wt% CNT was obtained in the same manner as in Example 3. Separately, a PDMS main agent and a curing agent are mixed at a ratio of 10:1, and hexane is added to this to obtain a 10% by volume PDMS/hexane solution (hereinafter sometimes referred to as "10 v/v% PDMS"). prepared.

A sacrificial layer was formed on the substrate in the same manner as in Example 1, and 0.01 wt % CNT was applied onto this substrate by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

Next, 10 v/v% PDMS was formed into a film by spin coating so as to cover the reinforcing layer 3, and then the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed.

After allowing to cool to room temperature, the polymer composite thin film 1 was peeled off from the substrate in the same manner as in Example 1. Thereafter, the peeled polymer composite thin film 1 was transferred to the support 4 to prepare the gas separator 6 . Hereinafter, the polymer composite thin film 1 produced in Example 7 is referred to as "10 v/v % PDMS/0.01 wt % CNT film".

FIG. 10 is a cross-sectional SEM image of a 10 v/v % PDMS/0.01 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 1740 nm±40 nm (average film thickness thickness = 1740 nm). In addition, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 2412 [GPU], the N ₂ permeability was 218 [GPU], and the O ₂ permeability was 481 [GPU]. Met.

0.01 wt% CNT was obtained in the same manner as in Example 3. Separately, the main agent of PDMS and the curing agent are mixed at a ratio of 10: 1, and hexane is added to this to obtain a 5% by volume PDMS/hexane solution (hereinafter sometimes referred to as "5v/v% PDMS"). prepared.

A sacrificial layer was formed on the substrate in the same manner as in Example 1, and 0.01 wt % CNT was applied onto this substrate by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

Next, 5 v/v% PDMS was formed into a film by spin coating so as to cover the reinforcing layer 3, and then the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed.

After allowing to cool to room temperature, the polymer composite thin film 1 was peeled off from the substrate in the same manner as in Example 1. Thereafter, the peeled polymer composite thin film 1 was transferred to the support 4 to prepare the gas separator 6 . Hereinafter, the polymer composite thin film 1 produced in Example 8 is referred to as "5 v/v % PDMS/0.01 wt % CNT film".

FIG. 11 is a cross-sectional SEM image of a 5 v/v % PDMS/0.01 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 1240 nm±10 nm (average film thickness thickness = 1240 nm). In addition, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 3162 [GPU], the N ₂ permeability was 288 [GPU], and the O ₂ permeability was 628 [GPU]. Met.

0.01 wt% CNT was obtained in the same manner as in Example 3. Separately, the main agent of PDMS and the curing agent are mixed at a ratio of 10: 1, and hexane is added to this to obtain a 3% by volume PDMS/hexane solution (hereinafter sometimes referred to as "3v/v% PDMS"). prepared.

A sacrificial layer was formed on the substrate in the same manner as in Example 1, and 0.01 wt % CNT was applied onto this substrate by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

Next, 3 v/v% PDMS was formed into a film by spin coating so as to cover the reinforcing layer 3, and then the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed.

After allowing to cool to room temperature, the polymer composite thin film 1 was peeled off from the substrate in the same manner as in Example 1. Thereafter, the peeled polymer composite thin film 1 was transferred to the support 4 to prepare the gas separator 6 . Hereinafter, the polymer composite thin film 1 produced in Example 9 is referred to as "3 v/v % PDMS/0.01 wt % CNT film".

FIG. 12 is a cross-sectional SEM image of a 3 v/v % PDMS/0.01 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 412 nm±15 nm (average film thickness thickness = 412 nm). In addition, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 8706 [GPU], the N ₂ permeability was 793 [GPU], and the O ₂ permeability was 1707 [GPU]. Met.

Polymer composite thin film 1 and gas separator 6 were prepared under the same conditions as in Example 9, except that the spin coating conditions for forming polymer thin film 2 were changed. Hereinafter, the polymer composite thin film 1 produced in Example 10 is referred to as "second 3 v/v % PDMS/0.01 wt % CNT film".

FIG. 13 is a cross-sectional SEM image of the second 3 v/v % PDMS/0.01 wt % CNT film. As shown in the figure, the boundary between the polymer thin film 2 and the reinforcing layer 3 is not clear, but the thickness D1 of the polymer composite thin film 1, which is the sum of the polymer thin film 2 and the reinforcing layer 3, is 341 nm±10 nm (average film thickness thickness = 341 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the CO ₂ permeability was 9956 [GPU], the N ₂ permeability was 900 [GPU], and the O ₂ permeability was 1924 [GPU]. Met.

Comparative example 1

In the same manner as in Example 1, 0.5 v / v% PDMS was prepared, a sacrificial layer was formed on the substrate, and then 0.5 v / v% PDMS was formed by spin coating. Heat was applied to cure the PDMS. Thus, a polymer thin film 2 (hereinafter sometimes referred to as "0.5 v/v % PDMS film") was formed. That is, in Comparative Example 1, the reinforcing layer 3 is not formed.

It should be noted that the film thickness of about 150 nm is the limit for the polymer thin film 2 composed only of PDMS to be self-supporting, and if the film is made thinner than that, the film breakage rate becomes extremely high. Therefore, in Comparative Example 1, the 0.5 v/v % PDMS film was scooped onto the PAN support membrane (support 4) in the stripping solution without being pulled up into the air.

The thickness of the 0.5 v/v % PDMS film of Comparative Example 1 was about 50 nm. A gas permeability test was performed and the _CO2 permeability was 39679 [GPU] and the _N2 permeability was 3654.

[Table 1] below shows the presence or absence of self-standing, the film thickness of the polymer composite thin film 1 (polymer thin film 2 + reinforcing layer 3), and the rotation speed of spin coating during PDMS film formation for Examples 1 to 10. , volume % of PDMS contained in polymer material-containing solution (PDMS concentration), weight % of CNT contained in CNT aqueous dispersion (CNT concentration), permeability of CO ₂ , N ₂ , O ₂ , selection for N ₂ The ratios are shown together. The data of Comparative Example 1 are also shown in [Table 1]. Further, (×2) in Examples 4 to 6 means that the polymer thin film 2 was formed in two steps.

As shown in [Table 1], all of Examples 1 to 10 were self-supporting, while Comparative Example 1 was not self-supporting. In addition, the presence or absence of self-standing is determined by removing the thin film from the base material in the stripping solution, and then lifting the film floating in the solution into the air without breaking, etc., and maintaining a flat film shape. It is judged based on the criteria of whether or not it can be held. That is, when the film structure is maintained without breaking even in the air, the self-supporting condition is “yes”, and when the film structure is suspended in the stripping solution after the substrate is removed, the film structure is maintained, but the film structure is taken out into the air. If it breaks easily, it is judged to be self-sustaining "none". It is clear that the reinforcement layer 3 containing the carbon nanotubes 5 greatly improved the mechanical strength of the polymer composite thin film 1 .

As shown in [Table 1], the average film thickness of each polymer composite thin film 1 produced in Examples 1 to 10 is in the range of 27 nm to 1740 nm (that is, 30 nm or more and 1700 nm or less). Here, in Examples 1 to 3, the PDMS concentration was set to 0.5% by weight, and only the CNT concentration was changed. According to Examples 1 to 3, it can be seen that the CNT concentration greatly affects the film thickness of the polymer composite thin film 1 .

As shown in Examples 1 to 6, in order to make the polymer composite thin film 1 thinner, it is effective to lower the PDMS concentration or the CNT concentration. On the other hand, as shown in Examples 7 to 10, it is possible to increase the thickness of the polymer composite thin film 1 by increasing the PDMS concentration. Furthermore, it is also effective to control the rotation speed during spin coating to a low speed for thickening the film. Conversely, for thinning, the rotation speed during spin coating should be controlled to a high speed. By controlling the CNT concentration or the rotation speed during spin coating, a polymer composite thin film 1 with a thickness of about 1000 nm can be produced.

The average film thickness of the polymer composite thin films 1 produced in Examples 7 to 10 is 341 nm to 1740 nm. As the film thickness increases, the gas permeability decreases. In addition, when the film is formed to such a thickness, the polymer thin film 2 is self-supporting even if it is composed only of PDMS, but by adding the reinforcing layer 3, the mechanical strength is extremely high and the durability is excellent. It becomes possible to realize the polymer composite thin film 1 . By increasing the mechanical strength, breakage of the polymer composite thin film 1 is prevented even if the pressure difference between the two surfaces of the film is increased, making it suitable for applications requiring extremely high durability, such as industrial plant applications. can be used for

Among Examples 1 to 10, only polymer composite thin film 1 obtained in Example 6 exceeded Comparative Example 1 in terms of gas permeability. However, from the viewpoint of mechanical strength (durability, robustness) required for industrial products and ease of handling based on these, Comparative Example 1 is not practical. On the other hand, Examples 1 to 10 are all self-supporting and have advantageous characteristics that Comparative Example 1 does not have. In particular, the polymer composite thin film 1 of Example 6 exceeds that of Comparative Example 1 in both gas permeability and self-standing (mechanical strength).

0.1 wt% CNTs were prepared in the same manner as in Example 1. Next, 0.1 wt % CNT was subjected to suction filtration once using a polycarbonate filter with a pore size of 10 μm, and then suction filtration was performed for the second and third times using a polycarbonate filter with a pore size of 5 μm. As a result, a post-filtration dispersion (hereinafter sometimes referred to as “post-filtration 0.1 wt % CNT”) was obtained.

A PDMS main agent and a curing agent were mixed at a ratio of 10:1, and hexane was added thereto to prepare a 10% by volume PDMS/hexane solution. A predetermined amount of hexane was added to this to prepare a 1.5 vol% PDMS/hexane solution (hereinafter sometimes referred to as "1.5 v/v% PDMS"), which was used in subsequent operations. .

Next, after forming a sacrificial layer on the base material, it was dried to further hydrophilize the surface of the base material. Furthermore, the 0.1 wt % CNTs after filtration produced by the above operation were applied onto this base material by spin coating, followed by heating and drying. The reinforcement layer 3 was formed by this.

Next, 1.5 v/v% PDMS was formed into a film by spin coating so as to cover the reinforcing layer 3, and then the substrate was heated to cure the PDMS. Thus, a polymer thin film 2 was formed.

After allowing to cool to room temperature, this base material was immersed in ethanol to dissolve the sacrificial layer, and the polymer composite thin film 1 in which the reinforcing layer 3 and the polymer thin film 2 were superimposed was peeled off from the base material. Hereinafter, the polymer composite thin film 1 prepared in Example 11 is referred to as "1.5 v/v % PDMS/0.1 wt % CNT film after filtration".

Comparative example 2

1.5 v/v % PDMS was prepared in the same manner as in Example 11. After forming a sacrificial layer on the base material, 1.5 v/v % PDMS was formed into a film by spin coating, and then the base material was heated to cure the PDMS. Thus, a polymer thin film 2 (hereinafter sometimes referred to as "1.5 v/v % PDMS film") was formed. That is, in Comparative Example 2, the reinforcing layer 3 is not formed.

Comparative Example 2 (1.5 v/v% PDMS film) in which the polymer thin film 2 was prepared under the same conditions as in Example 11 except that the reinforcing layer 3 was not provided, and Example 11 (1.5 v/v% PDMS/0.1 wt% CNT film after filtration) was evaluated in the bulge test.

FIGS. 14(a) and 14(b) are photographs showing deflection of the films obtained in Comparative Example 2 and Example 11 when the same load is applied. Here, FIG. 14(a) shows the state of 1.5 v/v % PDMS film, and FIG. 14(b) shows the state of 1.5 v/v % PDMS/0.1 wt % CNT film after filtration. Specifically, when the same load (water: 3.5 mL introduced, liquid pressure: about 437 Pa) was applied to Comparative Example 2 and Example 11, film deflection was observed.

15 is a graph showing the relationship between stress (σ) and deflection (ε) in the films obtained in Comparative Example 2 and Example 11. FIG. FIG. 15 shows the relationship between the applied pressure, the film radius, the film thickness, the deflection length, the stress (σ) calculated from the film arc length at the time of deflection, and the deflection (ε) for each film.

14 and 15, there is clearly a difference in film deflection under water pressure load between Comparative Example 2 and Example 11, and the mechanical properties of the polymer composite thin film 1 including the reinforcing layer 3 obtained in Example 11 A significant improvement in strength is evident. Furthermore, when the biaxial elastic modulus was calculated for Comparative Example 2 and Example 11, it was found that Example 11 showed a value 40 to 50 times that of Comparative Example 2.

(Second embodiment)
FIG. 16 is an explanatory view showing the configuration of the polymer composite thin film 1 and the gas separator 6 composed of the polymer composite thin film 1 according to the second embodiment. A second embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 16, the gas separator 6 is composed of the polymer composite thin film 1 and the support 4 . In the second embodiment, the polymer composite thin film 1 is constructed by uniformly dispersing the carbon nanotubes 5 in the polymer thin film 2 . Then, the polymer composite thin film 1 and the support 4 are superimposed so that they are in contact with each other to form the gas separator 6 . Of course, the polymer composite thin film 1 and the reinforcing layer 3 may be brought into close contact with each other and overlapped on the support 4 to form the gas separator 6 .

Examples of the polymer composite thin film 1 according to the second embodiment will be described below. The average film thickness of the polymer composite thin film 1 produced in the second embodiment (Examples 12 and 13) is in the range of 66 nm or more and 170 nm or less (for details, refer to the description of each example). reference).

<First step>
An aqueous CNT dispersion was prepared by adding a dispersant to 0.2% by weight of CNT, and this was diluted with ion-exchanged water to prepare a 0.01% by weight CNT aqueous dispersion. This was subjected to ultrasonic treatment and centrifugation treatment to obtain a supernatant liquid (0.01 wt % CNT).

Next, 0.01 wt% CNT was diluted 10-fold with ethanol to obtain a dispersion of water and ethanol (hereinafter sometimes referred to as "0.001 wt% CNT-ethanol dispersion"). That is, the first step in the second embodiment is a step of diluting a carbon nanotube aqueous dispersion containing carbon nanotubes 5 with a first solvent (here, ethanol) to prepare a water-first solvent dispersion.

<Second step>
Next, the main agent of polydimethylsiloxane (PDMS) resin (manufactured by Toray Dow Corning, SYLGARD184), which is one of silicone polymers, and a 0.001 wt% CNT-ethanol dispersion are kneaded in a defoaming kneader, and cured. The agent was added and further kneaded to obtain a mixed solution (hereinafter sometimes referred to as “PDMS-CNT”). That is, in the second step in the second embodiment, after adding the main agent of the polymeric material to the water-first solvent dispersion and kneading, a curing agent for curing the polymeric material is added and kneaded. This is the step of obtaining a mixed solution.

<Third step>
Hexane was added to this mixed solution to prepare a 2 vol% PDMS-CNT/hexane solution (hereinafter sometimes referred to as “2 v/v% PDMS-CNT”), which was used in subsequent operations. That is, the third step in the second embodiment is a step of diluting the mixed solution with a second solvent (here, hexane) to obtain a diluted mixed solution.

<Fourth step>
Prior to the preparation of the polymer composite thin film 1, first, a polyhydroxystyrene (PHS)/ethanol solution was spin-coated on the substrate to form a PHS layer (sacrificial layer), which was then dried, and the surface of the substrate was hydrophilized. . Furthermore, 2 v/v % PDMS-CNT prepared by the above-described operation was applied onto this substrate by spin coating, and heated and cured. Thus, a polymer composite thin film 1 was formed. That is, the fourth step in the second embodiment is a step of forming the polymer composite thin film 1 by applying and curing the diluted mixed solution so as to cover the sacrificial layer on the base material on which the sacrificial layer is formed. be.

<Fifth step>
After allowing to cool to room temperature, this base material was immersed in ethanol to dissolve the sacrificial layer, and the polymer composite thin film 1 was peeled off from the base material. The peeled polymer composite thin film 1 was self-supporting. Thereafter, the peeled polymer composite thin film 1 was transferred to the support 4 to prepare the gas separator 6 . Hereinafter, the polymer composite thin film 1 prepared in Example 12 is referred to as "2 v/v % PDMS-CNT film".

FIG. 17 is a cross-sectional SEM image of a 2 v/v % PDMS-CNT film. As shown, the film thickness D1 of the polymer composite thin film 1 was 170 nm±20 nm (average film thickness=170 nm). In addition, when a gas permeability test was performed on the obtained gas separator 6, the _CO2 permeability was 16934 [GPU], the _N2 permeability was 1560 [GPU], and the _O2 permeability was 3363. .

Polymer composite thin film 1 was prepared in the same step as in Example 12, except that in the third step described in Example 12, the amount of hexane added was changed and a 0.5% by volume PDMS-CNT/hexane solution was used. was formed. The polymer composite thin film 1 separated from the base material was self-supporting. Hereinafter, the polymer composite thin film 1 prepared in Example 13 is referred to as "0.5 v/v % PDMS-CNT film".

FIG. 18 is a cross-sectional SEM image of a 0.5 v/v % PDMS-CNT film. As shown, the film thickness D1 of the polymer composite thin film 1 was 66 nm±15 nm (average film thickness=66 nm). Further, when a gas permeability test was performed on the obtained gas separator 6, the _CO2 permeability was 25710 [GPU], the _N2 permeability was 2927 [GPU], and the _O2 permeability was 5922. .

The polymer composite thin films 1 obtained in Examples 12 and 13 each have a structure in which carbon nanotubes 5 are uniformly dispersed in PDMS as a polymer material. In the second step of the second embodiment, the mixed solution (PDMS-CNT) before being diluted with hexane specifically contains 1100 mg of the PDMS main agent, 110 mg of the curing agent, and 0.0016 mg of the carbon nanotubes 5. (strictly including water and ethanol). In the third step, the PDMS-CNT is diluted with hexane. In the fourth step, water, ethanol, and hexane are volatilized during the process of curing the polymer composite thin film 1 by heating, resulting in a polymer composite thin film. 1 is mainly composed of a polymer material and carbon nanotubes 5 .

At this time, the weight ratio of PDMS to carbon nanotube 5 is 1210:0.0016 (756250:1). Thus, in the second embodiment, the polymer composite thin film 1 contains an extremely small amount of carbon nanotubes 5 . The polymer composite thin films 1 produced in Examples 12 and 13 have average film thicknesses of about 170 nm and 66 nm, with no carbon nanotubes 5 exposed on the surface. Furthermore, considering the CO ₂ permeability, the N ₂ permeability (for example, Example 6), etc., even in the second embodiment, a very small amount of carbon nanotubes 5 constitute a sparse tube network in the polymer composite thin film 1. It is thought that And its mode is considered to be substantially equivalent to that shown in FIG.

That is, referring to FIG. 8, the polymer composite thin film 1 of the second embodiment has a first region A1 in which a plurality of carbon nanotubes 5 are present and a , a second region A2 in which a single carbon nanotube 5 is present, and a third region A3 in which no carbon nanotube 5 is present, and the area of the first region A1 is S1, and the second region is S1<S2<S3, where S2 is the area of A2 and S3 is the area of the third region A3.

Now, in Examples 12 and 13, ethanol was used as the solvent (first solvent) for diluting the aqueous CNT dispersion in the first step, and as the solvent (second solvent) for diluting the mixed solution in the third step. Although hexane is used, it is possible to use other solvents for the first and second solvents. That is, the first solvent (e.g., ethanol) is a solvent that is readily miscible with water and is readily miscible with a second solvent (e.g., hexane), and the second solvent is not completely miscible with water, but Any solvent that can be easily mixed with the mixed solution of water, the first solvent, and the polymer material (eg, PDMS-CNT described above) can be substituted.

(Third embodiment)
A third embodiment of the present invention will be described below. The polymer composite thin film 1 used in the third embodiment constitutes the gas separator 6 as described in the first and second embodiments. This gas separator 6 is incorporated in, for example, a gas separation device 10 and used for removing or concentrating a predetermined gas contained in the air.

As shown in FIG. 1(a), gas is supplied from the polymer thin film 2 side to the support 4 via the reinforcing layer 3 as a configuration for guiding the gas to the gas separator 6 described in the first embodiment. (hereinafter sometimes referred to as “a configuration in which the gas is supplied from the PDMS side”), and as shown in FIG. 2 and discharged from the support 4 (sometimes referred to as "a configuration in which the gas is supplied from the CNT side").

Gas separator 6 provided with 0.5 v/v% PDMS/0.1 wt% CNT film prepared in Example 1 (hereinafter sometimes referred to as “gas separator 6A”), and prepared in Example 2 A configuration in which gas is supplied from the PDMS side to the gas separator 6 (hereinafter sometimes referred to as "gas separator 6B") comprising a 0.5 v/v% PDMS/0.02 wt% CNT film; A gas separation test was conducted for each of the configuration in which the gas is supplied from the CNT side.

<Gas separator 6A>
Configuration in which gas is supplied from the PDMS side (see column of Example 1 in [Table 1])
_CO2 permeability: 3353 [GPU]
_CO2 / _N2 : 5.2
Configuration to supply gas from CNT side CO ₂ permeability: 187 [GPU]
_CO2 / _N2 : 1.6
<Gas separator 6B>
Configuration in which gas is supplied from the PDMS side (see column of Example 2 in [Table 1])
_CO2 permeability: 13019 [GPU]
_CO2 / _N2 : 7.4
Configuration to supply gas from the CNT side CO ₂ permeability: 11090 [GPU]
_CO2 / _N2 : 5.2

Thus, for both the gas separators 6A and 6B, the gas permeability was higher in the configuration in which the gas was supplied from the PDMS side than in the configuration in which the gas was supplied from the CNT side. Also, from the viewpoint of gas selectivity (CO ₂ /N ₂ ), the configuration in which the gas is supplied from the PDMS side showed better characteristics.

This means that the behavior (efficiency) of the molecules constituting the gas when permeating the polymer thin film 2 differs between the configuration in which the gas is supplied from the PDMS side and the configuration in which the gas is supplied from the CNT side. ing. Here, although PDMS has high mobility as a material, when the carbon nanotube 5 comes into contact with the surface of the polymer thin film 2 into which the gas flows, the mobility of the molecules constituting the gas is reduced. is supplied from the CNT side, the gas permeability is considered to deteriorate.

FIG. 19 is an explanatory diagram showing the configuration of a gas separator 10 to which the gas separator 6 is applied. As shown in FIG. 19, the gas separation device 10 includes a blower 14, a prefilter 11, a dust collection filter 12, and a gas separator 6, and a first blowout port 16a (and a second blowout port 16b) from a suction port 15. An air flow path 19 is formed through the .

The configuration of the gas separation device 10 of the third embodiment will be described below with reference to FIG. 19 . The blower 14 is composed of, for example, an air compressor. Air sucked from the suction port 15 by driving the air blower 14 passes through the flow path 19 in order of the pre-filter 11, the dust collection filter 12, and the gas separator 6 as an air flow AF.

The air that permeates the gas separator 6 is discharged from the first outlet 16a provided downstream of the gas separator 6 as an air flow AFO. On the other hand, the air that has not passed through the gas separator 6 is discharged from the second outlet 16b provided upstream of the gas separator 6 as an air flow AFN.

Here, in order to perform gas separation, a predetermined pressure difference is required between the space on the upstream side (the first space S1) and the space on the downstream side (here, the external space S0) across the gas separator 6. . In the gas separation apparatus 10 of the third embodiment, in order to secure the pressure difference, an air cock 17 is connected to the second blowout port 16b to limit the amount of outflow of the air flow AFN, and the compressed air is sent out by the blower 14. Thus, the first space S1 is adjusted to have a positive pressure with respect to the external space S0 (1 atmospheric pressure). In addition, the permeability of the polymer composite thin film 1 (see FIG. 1) mounted on the gas separator 6 is very high (for example, Examples 2 to 6, or Examples 9 and 10, etc. shown in [Table 1] ), the air pressure in the first space S1 can be set to a moderate value, for example, about 2 atmospheres (the difference in pressure between the first space S1 and the outer space S0=1 atmosphere).

The pre-filter 11 is a filter through which the air sucked by the blower 14 first passes, and collects relatively large dust contained in the airflow AF. The dust collection filter 12 is a filter through which the air that has passed through the pre-filter 11 passes next, and for example, a HEPA (High Efficiency Particulate Air) filter is preferably used. The HEPA filter has a collection rate of 99.97% or more for particles with a particle size of 0.3 μm contained in the air, and collects microparticles such as bacteria and PM2.5.

The gas separator 6 has therein the polymer composite thin film 1 described in the first embodiment. As for the relationship between the gas supplied to the gas separator 6 and the polymer composite thin film 1, the above-described "configuration to supply from the PDMS side" is adopted. That is, in the gas separator 6, the airflow AF is supplied from the polymer thin film 2 side and discharged from the support 4 side through the reinforcing layer 3 (see FIG. 1(a)).

Thus, the gas separation device 10 of the third embodiment includes the polymer composite thin film 1 described in the first embodiment or the second embodiment, and the gas supply unit ( Here, a blower 14) is provided.

Further, the gas separation device 10 includes the polymer composite thin film 1 described in the first embodiment, and a gas supply unit (blower 14) that supplies gas to the polymer composite thin film 1. The gas supply unit is , the polymer thin film 2 (second layer), and the reinforcing layer 3 (first layer) so that the gas permeates them in this order.

As shown in [Table 1], the polymer composite thin film 1 according to _{the present invention has a higher permeability of carbon dioxide (CO 2 )} and oxygen (O ₂ ) than nitrogen (N 2 ), so gas The air flow AFO that passes through the separator 6 and is discharged from the first outlet 16a has higher concentrations of O ₂ and CO ₂ than normal air (that is, oxygen-enriched air, carbon dioxide-enriched air ). On the other hand, the air flow AFN discharged from the second outlet 16b without passing through the gas separator 6 has a higher concentration of nitrogen than normal air (that is, nitrogen-enriched air).

If the gas separation device 10 has only the gas separation function, the pre-filter 11 and the dust collection filter 12 are not essential components. However, it is desirable to provide a pre-filter 11 and a dust collection filter 12 upstream of the gas separator 6 in order to prevent the polymer composite thin film 1 from clogging.

Since the air flow AFO is enriched with CO ₂ in the air, the gas separation device 10 can function as a CO ₂ recovery device that captures carbon dioxide-enriched air. Here, in the gas separator 6, a plurality of polymer composite thin films 1 may be provided in series to form a multistage configuration. Here, when the O ₂ /N ₂ selection ratio of one polymer composite thin film 1 is 2.2, the O ₂ /N 2 of the gas separator ₆ as a whole when the number of stages of the polymer composite thin film 1 is P. The selection ratio is 2.2̂P, and the oxygen concentration can be increased by increasing the number of stages. Of course, when P is increased, the total gas permeability in the gas separator 6 decreases. This case can be dealt with by increasing the capacity of the air compressor that constitutes the blower 14 .

For example, in "Polymer Journal (2021) 53:111-119 A new strategy for membrane-based direct air capture", the present inventors described that by making the polymer thin film 2 in the gas separator 6 a multistage configuration, air It has been reported that the CO ₂ (0.04%) inside can be concentrated to 40% or more. The gas separation device 10 with the multistage polymer thin film 2 can be introduced in various sizes and scales, and can be a new CO ₂ recovery technology (DAC).

Further, the airflow AFO is utilized in fish farms utilizing oxygen-enriched air, oxyfuel power plants, oxyfuel boilers, and the like. Although the airflow AFO has an increased CO ₂ concentration, it is relatively easy to remove CO ₂ from the airflow AFO by passing activated carbon, water, etc., for example, and the increase in CO ₂ concentration was suppressed. It is possible to obtain large amounts of oxygen-enriched air.

On the other hand, the airflow AFN can be used for fire fighting applications, for example. Combustion requires three elements: a combustible material, an oxygen supply, and an ignition source. However, combustion of combustible materials does not continue unless the concentration of oxygen in the air exceeds the limit. Combustion can be suppressed for most combustibles by keeping the nitrogen concentration above 85% (oxygen concentration below 14%). In other words, the fire can be extinguished by covering the burning material with nitrogen-enriched air. Water is often used as a fire extinguishing medium, but if it is difficult to do so, oxygen-diluted air can be substituted for water.

Furthermore, the airflow AFN (nitrogen-enriched air) can be utilized for corrosion and putrefaction suppression systems (preservation systems) for preventing the deterioration of foodstuffs, works of art, etc. due to oxidation.

In addition, in thermal power plants where fossil fuels such as coal, petroleum, and LNG gas are burned in a boiler and the power of the steam produced by the heat is used to turn a turbine to generate electricity, air flow AFO (oxygen enrichment) is normally used. On the other hand, if the boiler, etc. becomes abnormally hot due to a malfunction, etc., it is possible to prevent a fire by supplying air flow AFN (nitrogen enriched air). Become.

Among polysiloxanes, PDMS is known to have a particularly large free volume ratio. The cavity radius inside the polymer actually estimated by the positron annihilation method is 1 nm or less (Yampolskii, Pinnau, Freeman, 2006 John Wiley & Sons, Ltd "Materials Science of Membranes for Gas and Vapor Separation " p.125). Therefore, so-called nanoparticles exceeding this size are difficult to permeate the PDMS membrane, and the air flow AFO becomes clean air that does not even contain nanoparticles.

As described above, the gas separation device 10 equipped with the polymer composite thin film 1 according to the present invention has a function of removing nano-sized fine particles that cannot be removed even by the dust collection filter 12 described above, in addition to high permeability. By applying the polymer composite thin film 1, it is possible to realize a clean room system (air purifier) with extremely high cleanliness.

As described above, the polymer composite thin film 1 and the gas separation device 10 according to the present invention have been described based on specific embodiments or examples, but these are only examples, and the present invention is based on these embodiments and examples. It is not limited. For example, the "sparse tube network" (see FIG. 8) that constitutes the reinforcing layer 3 described in Example 6 can naturally be applied to other embodiments and examples.

The polymer composite thin film 1 according to the present invention has high functionality and high mechanical strength, and the gas separation device 10 provided with the polymer composite thin film 1 has high gas separation characteristics. CCS (Carbon dioxide Capture and Storage), which separates and captures _CO2 , which is a greenhouse gas generated in the air, from sources such as power plants and factories, and DAC, which directly captures _CO2 from the air. Is possible.

1 polymer composite thin film 2 polymer thin film (second layer)
3 Reinforcement layer (first layer)
4 support 5 carbon nanotube 6 gas separator 10 gas separator 14 blower

Claims (18)

A polymer composite thin film comprising a polymer material and carbon nanotubes and having selective permeability to a predetermined gas. a first layer containing the carbon nanotubes;
a second layer composed mainly of the polymeric material and superimposed so as to be in contact with the first layer;
2. The polymer composite thin film according to claim 1, wherein said second layer has selective permeability to a predetermined gas. 3. The polymer composite thin film according to claim 2, wherein the total average thickness of the superimposed first layer and second layer is 1700 nm or less. 3. The polymer composite thin film according to claim 2, wherein the total average thickness of the superimposed first layer and second layer is 120 nm or less. 3. The polymer composite thin film according to claim 2, wherein the total average thickness of the superimposed first layer and second layer is 50 nm or less. 3. The polymer composite thin film according to claim 2, wherein the total average thickness of the superimposed first layer and second layer is 30 nm or less. The first layer has, in its plane A,
In the thickness direction of the first layer,
a first region A1 in which the plurality of carbon nanotubes are present;
a second region A2 in which the single carbon nanotube is present;
a third region A3 in which the carbon nanotubes are absent;
The polymer composite thin film according to any one of claims 2 to 6, comprising: The polymer composite thin film according to any one of claims 2 to 7, wherein the second layer selectively permeates carbon dioxide and oxygen. 2. The polymer composite thin film according to claim 1, wherein said carbon nanotubes are dispersed in said polymer material and have selective permeability to a predetermined gas. In the plane A of the polymer composite thin film,
In the thickness direction of the polymer composite thin film,
a first region A1 in which the plurality of carbon nanotubes are present;
a second region A2 in which the single carbon nanotube is present;
a third region A3 in which the carbon nanotubes are absent;
The polymer composite thin film according to claim 9, comprising: S1<S2<S3, where S1 is the area of the first area A1, S2 is the area of the second area A2, and S3 is the area of the third area A3. The polymer composite thin film according to claim 7 or 10, characterized by: 12. The polymer composite thin film according to any one of claims 1 to 11, wherein polysiloxane is mainly used as the polymer material. A polymer composite thin film according to any one of claims 1 to 12,
a gas supply unit that supplies gas to the polymer composite thin film;
A gas separation device comprising: A polymer composite thin film according to any one of claims 2 to 8,
a gas supply unit that supplies gas to the polymer composite thin film;
with
The gas separation device, wherein the gas supply unit supplies the gas so that the gas permeates the second layer and the first layer in this order. A first step of preparing a carbon nanotube aqueous dispersion containing carbon nanotubes and preparing a polymer material-containing solution containing a polymer material;
a second step of applying and drying the aqueous dispersion of carbon nanotubes on the substrate on which the sacrificial layer is formed so as to cover the sacrificial layer, thereby forming a first layer mainly composed of the carbon nanotubes; ,
a third step of applying and curing the polymer material-containing solution so as to cover the first layer to form a second layer;
a fourth step of dissolving the sacrificial layer and peeling the polymer composite thin film composed of the first layer and the second layer from the substrate;
A method for producing a polymer composite thin film, comprising: The first step includes a filtration step of filtering the aqueous carbon nanotube dispersion to produce a post-filtration dispersion, wherein at least a portion of the aggregates of the carbon nanotubes are removed from the aqueous carbon nanotube dispersion by the filtration step. 16. The method for producing a polymer composite thin film according to claim 15, wherein the size of the carbon nanotubes contained in the post-filtration dispersion is restricted while removing the . a first step of diluting a carbon nanotube aqueous dispersion containing carbon nanotubes with a first solvent to prepare a water-first solvent dispersion;
a second step of adding a main agent of a polymeric material to the water-first solvent dispersion and kneading, adding a curing agent for curing the polymeric material, and kneading the mixture to obtain a mixed solution;
a third step of diluting the mixed solution with a second solvent to obtain a diluted mixed solution;
a fourth step of applying and curing the post-dilution mixed solution to form a polymer composite thin film so as to cover the sacrificial layer on the substrate on which the sacrificial layer is formed;
a fifth step of dissolving the sacrificial layer and peeling the polymer composite thin film from the substrate;
A method for producing a polymer composite thin film, comprising: 18. The method for producing a polymer composite thin film according to claim 17, wherein the first solvent is ethanol and the second solvent is hexane.

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