JP2010162788A - Tubular structure for transferring aqueous solution, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tubular structure requiring no washing by making the internal wall of the tubular structure completely super-hydrophobic, and a method for easily and efficiently producing the tubular structure. <P>SOLUTION: The tubular structure for transferring an aqueous solution is formed by coating the internal wall surface of a tubular solid base material (X) with a super-hydrophobic coat made of a nano-structure (Y) obtained by bonding a hydrophobic group (C) to silica nano-fiber (B). The method for producing the tubular structure for transferring the aqueous solution includes forming a polymer layer with a polyethylene-imine skeleton on the inner surface of the tubular solid base material (X), bringing the polymer layer into contact with a silica source liquid, and then performing hydrophobic treatment to form the internal wall of the base material (X) into a super-hydrophobic surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tubular structure used for aqueous solution movement, and more specifically, the inner wall of the tubular structure is covered with a superhydrophobic coating that completely repels water, so that the inner wall of the tubular structure is flowed even after flowing an aqueous solution. The present invention relates to a tubular structure that can be used as it is without washing, and a method for manufacturing the same.

  By making the solid surface superhydrophobic, that is, by increasing the contact angle of water droplets, water cannot adhere to the solid surface, and a surface function that can be called self-cleaning can be expressed. In particular, on a solid surface having a water contact angle of 170 ° or more, the water droplets roll on the surface and maintain a clean state for a long time without leaving traces of contact with water. In other words, even after an aqueous solution is poured into a container having a superhydrophobic surface, even the droplets of the solution are not left on the inner wall of the container and can be kept completely clean. Therefore, the container can be used repeatedly without washing.

  The lotus leaf in nature is the most typical example with a self-cleaning function. Lotus leaves are superhydrophobic (also called superhydrophobic), but their functions are closely related to the leaf surface structure. That is, the surface layer is formed while the nanofibers are spread over the entire surface, and micron-sized protrusions such as nanofiber aggregates are formed on the outermost surface layer at a certain distance. Hydrophobic wax is present on the surface. As a result, water does not adhere to the surface but rolls on the surface of the lotus leaf, and a so-called self-cleaning function is developed that removes surface dirt and the like by the rolling force.

  Many attempts have been made to construct a flat solid surface that exhibits superhydrophobicity by imitating a lotus leaf. For example, it has been reported that the contact angle is increased to 170 ° or more by regularly arranging the carbon nanotubes on the surface of the substrate (see, for example, Non-Patent Document 1). In addition, it has been reported that polypyrrole nanofibers are grown on a platinum-coated silicon surface by an electrochemical process to increase the surface contact angle to 170 ° or more (see, for example, Non-Patent Document 2). In addition, after forming a zinc oxide nanocrystal seed film on the surface of a glass substrate at a temperature of 400 ° C. or higher, super-hydrophobicity is manifested by growing an infinite number of rod-shaped zinc oxide nanofibers on the film. (For example, see Non-Patent Document 3).

  As a simple method, for example, a certain poor solvent is added to a solution of polypropylene, and it is cast on the surface of a substrate, and the temperature is adjusted, thereby forming a network structure composed of polypropylene nanoparticles, and thereby a contact angle. Has been reported to be increased to 160 ° (for example, see Non-Patent Document 4). In addition, a glass composed of oxides of silicon, boron, and sodium has a phase separation structure, and it is further etched by chemical treatment to induce a concavo-convex structure on the surface, and finally a fluorine compound is applied to the surface. It has also been shown that superhydrophobicity can be expressed by reaction (see, for example, Patent Document 1). Furthermore, after producing a laminated film of polyarylamine and polyacrylic acid, the surface is treated with a chemical method to induce a surface porous structure, and silica nanoparticles are fixed thereon, and finally a fluorinated alkyl. It is also known to construct a superhydrophobic surface by treating with a silane coupling agent having a residue (see, for example, Patent Document 2).

  Among the methods proposed above, in the case of a superhydrophobic surface based on an inorganic material, the process of producing the surface roughness provided with the nanostructure is complicated and expensive. Further, in the case of a superhydrophobic surface based on an organic polymer, the cost is low, but the solvent resistance and corrosion resistance of the obtained superhydrophobic surface are low, which causes a practical problem. Furthermore, the method proposed above is characterized in that it is produced on a planar solid surface, but there is no example in which a limited space called an inner wall of a tubular base material is covered with an inorganic material-based superhydrophobic surface.

Special table 2008-508181 US Patent Application Publication No. 2006/029808

Sun et al. , Acc. Chem. Res. 2005, 38, 644-652. Li et al. , J .; Mater. Chem. , 2008, 18, 2276-2280 Feng et al. , J .; Am. Chem. Soc. , 2004, 126, 62-63 Erbil et al. , Science, 2003, 299, 1377-1380

  In view of the above circumstances, the problem to be solved by the present invention is to provide a tubular structure that does not require cleaning by completely superhydrophobizing the inner wall of the tubular structure, and a simple and efficient manufacturing method thereof. is there.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a fiber-like nanostructure obtained by combining an organic polymer and an inorganic silica on the nanometer order is a tubular substrate. Tubular with a superhydrophobic surface by forming a nanostructure of complex structure on the substrate as a coating that spreads over the entire inner surface and completely covers the inner wall, and then hydrophobizing the surface The present inventors have found that a structure can be obtained and have completed the present invention.

  That is, the present invention provides a tubular structure in which the inner wall surface of a tubular substrate is coated with the superhydrophobic coating on the inner wall surface of a tubular solid substrate, and the superhydrophobic coating is hydrophobic on silica nanofibers. The present invention provides a tubular structure for transferring an aqueous solution characterized by comprising a nanostructure formed by bonding groups, and a method for producing the same.

  The tubular structure having a superhydrophobic surface of the present invention is mainly composed of a substrate such as glass, inorganic metal oxide, plastic, etc., and the solution does not adhere even after flowing an aqueous solution. It does not require post-treatment such as washing and drying. Moreover, the manufacturing method of this structure can be implemented with a general purpose equipment, and can be manufactured simply and at low cost. Therefore, the tubular structure for moving an aqueous solution provided by the present invention can be applied not only to the chemical industry using a precision synthesizer but also to medical fields.

2 is a scanning electron micrograph obtained in Example 1 before hydrophobization treatment. It is the high-speed camera photograph of the moment of the water droplet which flows in the glass tube tube after the hydrophobization process obtained in Example 1. FIG. The third part of FIG. 2 shows the calculation of the water droplet contact angle. 2 is a digital photograph of a solution obtained by washing a pipette after flowing a copper nitrate solution in Example 2. FIG. a is the cleaning solution from the pipette of the superhydrophobic inner wall, and b is the cleaning solution from the ordinary glass pipette. It is a UV-Vis spectrum of the solution obtained by flowing a copper nitrate solution in Example 2 and then washing the pipette. a is the cleaning solution from the pipette of the superhydrophobic inner wall, and b is the cleaning solution from the ordinary glass pipette. FIG. 4 is a UV-Vis spectrum of a solution obtained by washing a pipette after flowing a cobalt nitrate solution in Example 3. FIG. a is the cleaning solution from the pipette of the superhydrophobic inner wall, and b is the cleaning solution from the ordinary glass pipette.

  The present inventors have already used a crystalline aggregate in which a polymer having a linear polyethyleneimine skeleton grows in an aqueous medium in a self-organizing manner as a reaction field, and hydrolyzes alkoxysilane on the surface of the aggregate in a solution. Provided is a silica-containing nanostructure having a complicated shape having a nanofiber as a basic unit, which is obtained by decomposing condensation and precipitating silica (Japanese Patent Laid-Open No. 2005-264421, Japanese Patent Laid-Open No. 2005-336440, (See JP 2006-063097 A and JP 2007-051056 A.)

  The basic principle of this technique is to spontaneously grow a crystalline aggregate of a linear polyethyleneimine skeleton-containing polymer in a solution. Once a crystalline aggregate is formed, the crystalline aggregate is then simply used. A silica source is mixed in the dispersion liquid, and the deposition of the silica only on the surface of the crystalline aggregate is allowed to leave naturally (so-called sol-gel reaction). The silica-containing nanostructures obtained by this method basically have nanofibers as units for structure formation, and the spatial arrangement of these units induces the shape of the entire structure, so that nano-level gaps are not generated. Many have a large surface area. This is considered to be an efficient process that satisfies the rough surface structure formation at the nano level.

  The growth of the crystalline aggregate of the linear polyethyleneimine skeleton-containing polymer in the solution proposed above proceeds on the surface of a solid substrate of an arbitrary shape, and the layer of the crystalline association of the polymer on the substrate If it can form, it is thought that the nanostructure which has a new surface by which the silica and the polymer were compounded on the solid substrate can be constructed.

  Therefore, the fundamental problem in solving the above problem is only how to form a stable layer (film) of a self-assembled aggregate of linear polyethyleneimine skeleton-containing polymers on the surface of the solid substrate. An important feature of a polymer containing a polyethyleneimine skeleton is that it is basic and has a very high polarity. Therefore, the linear polyethyleneimine skeleton-containing polymer is a metal substrate, a glass substrate, an inorganic metal oxide substrate, a plastic substrate having a polar surface, a cellulose substrate, many electron acceptor substrates, Lewis acid It has a strong interaction force (adsorption force) with various surfaces such as base materials, acidic base materials, polar base materials, and hydrogen-bonding base materials. Taking advantage of this feature of the linear polyethyleneimine skeleton-containing polymer, the present inventors contacted (immersed) the inner surface of the tubular solid substrate with a molecular solution of the polyethyleneimine skeleton-containing polymer having a constant concentration and a constant temperature. The polymer in the solution is sucked to the inner surface of the tubular solid substrate, and as a result, a layer composed of molecular aggregates of the polymer can be easily formed over the entire contacted portion of the inner surface of the solid substrate. I found. Furthermore, the tubular solid base material having the polymer layer thus obtained on the inner wall is brought into contact with the silica source liquid, so that the inner surface of the tubular solid base material is a composite of silica and polymer having a complicated structure. A surface that exhibits superhydrophobicity was constructed on the inner surface of the tubular solid substrate by chemically bonding silanes having hydrophobic groups to the silica part of the nanostructure.

  In addition, in this invention, a nanostructure means the structure which has a fiber shape which consists of a repeating unit (unit) of nanometer order. The nanostructure (y1) is a structure made of nanofibers having the above-mentioned polymer and silica as main constituent components, and the nanostructure (y2) is a structure made of nanofibers having silica as main constituent components. . By subjecting these nanostructures (y1) and (y2) to a hydrophobic treatment, a nanostructure (Y) that forms a superhydrophobic film can be obtained.

  The tubular structure for aqueous solution transfer (hereinafter abbreviated as structure) of the present invention is such that the inner wall surface of the tubular solid substrate (X) is coated with a superhydrophobic coating, and the superhydrophobic coating is silica nanofiber (B). It consists of a nanostructure (Y) formed by bonding a hydrophobic group (C). Specifically, a fiber-shaped nanostructure material (y1) in which the inner wall surface of the tubular solid substrate (X) contains a polymer (A) having a polyethyleneimine skeleton (a) and silica, or the nanostructure (y1) The polymer (A) in the inside is coated with a fiber-like nanostructure material (y2) obtained by removing by baking, and a hydrophobic group (C) is bonded to the surface of the structure.

[Tubular solid substrate (X)]
The tubular solid substrate (X) used in the present invention is not particularly limited as long as the polymer (A) having a linear polyethyleneimine skeleton (a) described later can be adsorbed. For example, inorganic material base materials such as glass, metal, metal oxide, organic material base materials such as resin (plastic), cellulose, fiber, paper, etc. Furthermore, glass, metal, metal oxide, plastic surface Chemically treated substrates can be used.

  Although it does not specifically limit as an inorganic material type glass substrate, For example, glass, such as heat resistant glass (borosilicate glass), soda-lime glass, crystal glass, optical glass which does not contain lead and arsenic, is used suitably. Can do. In the use of a glass substrate, the surface can be used by etching with an alkaline solution such as sodium hydroxide, if necessary.

  Although it does not specifically limit as an inorganic material type metal base material, For example, the base material which consists of iron, copper, aluminum, stainless steel, zinc, silver, gold | metal | money, platinum, or these alloys etc. can be used suitably.

  Although it does not specifically limit as an inorganic material type metal oxide base material, For example, a tin oxide, copper oxide, a titanium oxide, a zinc oxide, an alumina etc. can be used suitably.

  As the resin base material, for example, processed products of various polymers such as polyethylene, polypropylene, polycarbonate, polyester, polystyrene, polymethacrylate, polyvinyl chloride, polyethylene alcohol, polyimide, polyamide, polyurethane, epoxy resin, and cellulose can be used. it can. In the use of various polymers, the inner wall surface may be chemically treated or treated with sulfuric acid or alkali as necessary.

  The minimum inner diameter of the tubular solid substrate (X) is 10 μm because it is necessary to form a superhydrophobic film, which will be described later, on the inner surface thereof. it can. The tubular structure in the present invention does not necessarily need to use a tubular solid base material having a uniform inner diameter, and does not need to have a shape having two or more outlets for an aqueous solution, such as a flask and a beaker. An aqueous solution moving tubular structure used for temporarily holding the aqueous solution and then transferring it to another container or the like may be used.

  In the method for producing the structure of the present invention, which will be described later, when removing the polymer (A) by the firing step, it is needless to say that a tubular solid substrate made of a material that does not deteriorate at the firing temperature must be used.

[Polymer having Polyethyleneimine Skeleton (a) (A)]
In the present invention, it is essential to use the polymer (A) having the linear polyethyleneimine skeleton (a) for the polymer layer formed on the tubular solid substrate (X). The polymer (A) having the linear polyethyleneimine skeleton (a) may be a linear, star-like or comb-like homopolymer, or a copolymer having other repeating units. good. In the case of a copolymer, the molar ratio of the linear polyethyleneimine skeleton (a) in the polymer (A) is preferably 20% or more from the viewpoint that a stable polymer layer can be formed. A block copolymer having a repeating polyethyleneimine skeleton (a) having 10 or more repeating units is more preferable.

  The polymer having the linear polyethyleneimine skeleton (a) may be a homopolymer or a copolymer, and the molecular weight corresponding to the polyethyleneimine skeleton portion is in the range of 500 to 1,000,000. When it exists, it is preferable from the point which can form a stable polymer layer on base material (X). The polymer (A) having the linear polyethyleneimine skeleton (a) can be obtained from a commercially available product or a synthesis method already disclosed by the present inventors (see the above-mentioned patent document).

  As will be described later, the polymer (A) can be used by dissolving in various solutions. At this time, in addition to the polymer (A) having a linear polyethyleneimine skeleton (a), the polymer (A) It can be used by mixing with other polymers that are compatible with. Examples of the other polymer include polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, poly (N-isopropylacrylamide), polyhydroxyethyl acrylate, polymethyloxazoline, polyethyloxazoline, and polypropyleneimine. By using these other polymers, it is possible to easily adjust the thickness of the nanostructure (Y) on the surface of the resulting structure, that is, the thickness of the superhydrophobic coating.

[Silica nanofiber (B)]
The inner wall surface of the tubular structure obtained by the present invention has silica nanofibers (hereinafter referred to as nanostructure (y1)) containing the polymer (A) and silica as main constituents, or silica nanofibers containing silica as the main constituent. It is a great feature that it is coated with a fiber (hereinafter referred to as nanostructure (y2)). As a silica source required for silica formation, for example, alkoxysilanes, water glass, hexafluorosilicon ammonium and the like can be used. The term “main component” means that other components are not included in addition to substances derived from impurities or side reactions in the raw material unless the third component is intentionally mixed. .

  As the alkoxysilanes, tetramethoxysilane, oligomers of methoxysilane condensates, tetraethoxysilane, oligomers of ethoxysilane condensates can be suitably used. Further, alkyl-substituted alkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, iso-propyltrimethoxysilane, iso-propyltriethoxysilane, etc., 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycid Xylpropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptotriethoxysilane, 3,3 -Trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, p -Chloromethylphenyltrimethoxysilane, p-chloromethylphenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane and the like can be used alone or in combination.

  In addition, other silica metal compounds may be mixed with the silica source. For example, tetrabutoxytitanium, tetraisopropoxytitanium, or an aqueous solution of titanium bis (ammonium lactate) dihydroxide stable in an aqueous medium, an aqueous solution of titanium bis (lactate), a propanol / water mixture of titanium bis (lactate), titanium (ethyl) Acetoacetate) diisopropoxide, titanium sulfate, hexafluorotitanium ammonium and the like can be used.

[Nanostructure (y1) containing polymer (A) and silica]
The nanostructure (y1) containing the polymer (A) and silica is basically a silica nanofiber (B) having a structure in which the polymer (A) is coated with silica, and this is a space on the substrate surface. While changing the arrangement, a state of covering the whole is formed, and a complicated structure is formed. For example, a rice field in which nanofabrics are formed on the entire inner surface on the tubular solid substrate (X) mainly with the long axis of the fiber growing in the vertical direction (nano turf) or slightly tilted from the vertical direction Shape (nano rice field), tatami shape (nano tatami mat) in which nanofibers lie down on the entire surface of the substrate, sponge shape in which the nanofibers form a network on the entire surface of the substrate and have a net-like structure A wide variety of hierarchical structures such as (nano sponge) can be formed.

  The thickness of the silica nanofiber (B) of the basic unit in the higher-order structure such as the nano turf shape, the nano rice field shape, the nano tatami shape, or the nano sponge shape is in the range of 10 to 200 nm, and the aspect ratio is 2 or more. is there. The length (major axis direction) of the nanofiber in the nano turf shape or the nano rice field shape can be controlled in the range of 50 nm to 2 μm.

  The thickness when coating the inner surface of the tubular solid substrate (X) is related to the spatial arrangement state of the silica nanofiber (B), but can be varied in the range of approximately 50 nm to 20 μm. It is preferable to adjust by such as. Nano-turf shape is characterized by a strong tendency of nanofibers to stand upright, the length of the fibers basically constituting the thickness, and the length of each fiber is fairly uniform. In the nano rice field, the nanofibers tend to extend obliquely, and the coating thickness is smaller than the fiber length. In addition, the thickness of the nano rice field-like layer is characterized by being determined by the overlaid state of the nanofibers. The thickness of the nanosponge-like layer is characterized in that it is determined by the degree to which the nanofibers are swelled by complex entanglements having regularity. When a network is formed, the thickness is determined depending on the overlapping state.

  In the nanostructure (y1), the component of the polymer (A) can be adjusted at 5 to 30% by mass. The spatial arrangement structure (higher order structure) can be changed by changing the content of the polymer (A) component.

[Nanostructure comprising silica as main component (y2)]
The nanostructure (y1) containing the polymer (A) obtained above and silica is baked together with the tubular solid substrate (X), so that the silica from which the polymer (A) has been removed is the main component. The structure covered with the silica nanofiber (B) which is the nanostructure (y2) to be obtained can be obtained. At this time, the polymer (A) disappears by firing, but the silica maintains its structure. Accordingly, the shape of the nanostructure (y2) is also determined by the spatial arrangement of the nanostructure (y1). That is, for example, the nanofabric is a turf shape (nano turf) in which the major axis of the fiber grows mainly on the entire surface of the solid substrate, or a rice field that is slightly tilted from the vertical direction (nano rice field) ), Tatami shape (nano tatami mat) in which nanofibers lie down on the entire surface of the substrate, and sponge shape (nano sponge) in which nanofibers form a network on the entire surface of the substrate. Make up structure.

[Hydrophobic treatment]
In the present invention, the surface of the nanostructure (y1) or nanostructure (y2), which is a silica nanofiber (B), must be modified with a hydrophobic group in order to obtain a superhydrophobic surface. The modification can be easily performed by contact with a compound having a hydrophobic group.

  Examples of the hydrophobic group include an alkyl group having 1 to 22 carbon atoms and an aromatic group which may have a substituent (as the substituent, an alkyl group having 1 to 22 carbon atoms, a fluorinated alkyl group, Hydrophobic groups such as partially fluorinated alkyl groups), fluorinated alkyl groups having 1 to 22 carbon atoms, and partially fluorinated alkyl groups having 1 to 22 carbon atoms.

  In order to efficiently modify these hydrophobic groups on the silica nanofiber (B), it is preferable to use a silane coupling agent having the hydrophobic group alone or in combination.

  Examples of the silane coupling agent include methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, iso-propyltrimethoxysilane, iso Examples thereof include alkyltrimethoxysilanes or alkyltrichlorosilanes having an alkyl group having 1 to 22 carbon atoms such as propyltriethoxysilane, pentyltrimethoxysilane, and hexyltrimethoxysilane.

  Further, as having a fluorine atom effective for lowering the surface tension, a (partially) silane coupling agent having a fluorinated alkyl group, such as 3,3,3-trifluoropropyltrimethoxysilane, tridecafluoro-1, 1,2,2-tetrahydrooctyl) trichlorosilane and the like can also be used.

  Moreover, as a silane coupling agent having an aromatic group, phenyltrimethoxysilane, phenyltriethoxysilane, p-chloromethylphenyltrimethoxysilane, p-chloromethylphenyltriethoxysilane, and the like can be taken up.

  In addition to the introduction of hydrophobic groups by the above chemical bonds, silica nanofibers (B) can be used to physically apply water-insoluble polyacrylate polymers, polyamide polymers, long-chain alkylamine compounds having an alkyl group having 1 to 22 carbon atoms, and the like. Hydrophobic groups can also be introduced by adsorption.

[Method for producing tubular structure having superhydrophobic surface]
In the method for producing a structure of the present invention, the inner wall of the tubular solid substrate (X) is contacted with a solution containing the polymer (A) having a polyethyleneimine skeleton (a), and the tubular solid substrate (X) The step (1) of forming a polymer layer on the inner surface, the tubular solid substrate (X) having the polymer layer obtained above, and the silica source liquid (B ′) are contacted to form a tubular solid substrate (X ) Step (2) for producing silica nanofibers (B) in the polymer layer on the inner surface, and silica nanofibers (B) on the inner surface of the tubular solid substrate (X) obtained in the step (2) A tubular structure having a superhydrophobic surface in which polyethyleneimine is contained in the surface composition after the step (3) of treating with a silane coupling agent (C ′) having Can be manufactured.

  Furthermore, in the method for producing a structure of the present invention, after the step (2), the tubular solid substrate (X) whose inner surface is coated with the silica nanofiber (B) is fired, and the polyethyleneimine skeleton (a ) Having a step (3 ′) of removing the polymer (A) having heat treatment, followed by a step (4) of treating with a silane coupling agent (C ′) having a hydrophobic group. Yes, it is possible to produce a structure having a superhydrophobic surface in which polyethyleneimine is not included in the surface composition.

  As the polymer (A) having the polyethyleneimine skeleton (a) used in the step (1), the aforementioned polymer can be used. In addition, the solvent that can be used for obtaining the solution of the polymer (A) is not particularly limited as long as the polymer (A) can be dissolved, and examples thereof include water, organic solvents such as methanol and ethanol, These mixed solvents can be used as appropriate.

  The concentration of the polymer (A) in the solution is not particularly limited as long as the polymer layer can be formed on the tubular solid substrate (X). When it does, it is preferable that it is the range of 0.5 mass%-50 mass%, and it is more preferable in it being the range of 5 mass%-50 mass%.

  In the solution of the polymer (A) having a polyethyleneimine skeleton (a), the above-mentioned other polymers that are soluble in the solvent and compatible with the polymer (A) can be mixed. The mixing amount of the other polymer may be higher or lower than the concentration of the polymer (A) having the polyethyleneimine skeleton (a).

  Moreover, in order to produce a polymer layer in a process (1), tubular solid base material (X) is made to contact with the solution of a polymer (A). As the contact method, it is preferable to immerse the desired tubular solid substrate (X) in the solution of the polymer (A).

  In the dipping method, the substrate and the solution can be brought into contact with each other in a manner in which the substrate is placed in the solution or the solution is placed in the substrate depending on the state of the substrate. During the immersion, the temperature of the polymer (A) solution is preferably in a heated state, and a temperature of about 50 to 90 ° C. is suitable. The time for contacting the tubular solid substrate (X) with the solution of the polymer (A) is not particularly limited, and is preferably selected within a few seconds to 1 hour according to the material of the substrate (X). When the material of the base material has a strong binding ability with polyethyleneimine, for example, it may be several seconds to several minutes for glass, metal, etc. good.

  After contacting the tubular solid substrate (X) with the polymer (A) solution, the substrate is removed from the polymer (A) solution and allowed to stand at room temperature (around 25 ° C.). An aggregate layer is formed on the surface of the substrate (X). Alternatively, the substrate (X) is taken out from the solution of the polymer (A), and then immediately put into distilled water at 4 to 30 ° C. or an aqueous ammonia solution at a room temperature to a freezing temperature, whereby the spontaneous polymer (A) An aggregate layer may be formed.

  In the step (2), the polymer layer formed via the step (1) is brought into contact with the silica source liquid (B ′) to deposit silica (B) on the surface of the polymer layer, and the polymer (A) and silica (B ) And a nanostructure (y1).

  As the silica source liquid (B ′) used at this time, the above-mentioned various silica source aqueous solutions, alcohol solvents, for example, aqueous organic solvent solutions such as methanol, ethanol and propanol, or mixed solvents of these with water A solution can be used. Moreover, the water glass aqueous solution which adjusted the pH value to the range of 9-11 can also be used. The silica source liquid (B ′) to be used can be mixed with a metal alkoxide other than silica.

  Moreover, the alkoxysilane compound as a silica source can be used even in a solvent-free bulk liquid.

  As a method for bringing the solid substrate formed with the polymer layer into contact with the silica source liquid (B ′), an immersion method can be preferably used. It is sufficient that the immersion time is 5 to 60 minutes, but the time can be further increased as necessary. The temperature of the silica source liquid (B ′) may be room temperature or a heated state. In the case of heating, it is desirable to set the temperature to 70 ° C. or lower in order to regularly precipitate silica on the surface of the tubular solid substrate (X).

  By selecting the type and concentration of the silica source, the structure of the nanostructure (y1) of the precipitated silica and the polymer (A) can be adjusted, and the type and concentration of the silica source are appropriately selected according to the purpose. It is preferable to select.

  When the polymer (B) in the nanostructure (y1) is removed by heating and baking to obtain the nanostructure (y2), the baking temperature can be set to 300 to 600 ° C. When this step is performed, the tubular solid substrate (X) is selected from heat-resistant inorganic materials such as glass, metal oxide, and metal.

  The heating and firing time is desirably in the range of 1 to 7 hours, but it may be fired for a short time when the temperature is high, and it is preferable to appropriately adjust the time such as increasing the time when the temperature is low.

  Through the step of bringing the tubular solid substrate (X) coated with the nanostructure (y1) or nanostructure (y2) obtained above into contact with the silane coupling agent having a hydrophobic group described above, Convert the surface to superhydrophobic.

  At this time, the silane coupling agent having a hydrophobic group can be used by dissolving in a solvent such as chloroform, methylene chloride, cyclohexanone, xylene, toluene, ethanol, methanol and the like. These solvents can be used alone or in combination, and the concentration of the silane coupling agent is preferably adjusted to 1 to 5 wt%.

  Furthermore, it is desirable to use the above solution by mixing it with an ethanol solution of 1-5 wt% ammonia water. As a volume ratio at the time of mixing, it is suitable to make the ammonia water ethanol solution into the range of 5-10 equivalent with respect to 1 equivalent of a silane coupling agent solution.

  The contact with the silane coupling agent is preferably carried out by a method of immersing in the mixed solution obtained above, and the silica nano where the alkylsilane of the silane coupling agent is the nanostructure (y1) or nanostructure (y2). It can be converted into a tubular structure having a superhydrophobic surface composed of the final nanostructure (Y), introduced by Si—O—Si bond to the surface of the fiber (B).

  The immersion time in the solution is preferably in the range of 1 hour to 3 days, and is suitably selected depending on the concentration of the silane coupling agent and the concentration of ammonia in the solution. The contact angle can be gradually increased as the immersion time is increased in the solution having a constant concentration, and the contact angle becomes close to the maximum value of 180 ° after the fixed time. When this number appears, the introduction of hydrophobic residues on the surface can be considered saturated. Depending on the desired level of hydrophobicity, the immersion time can be selected.

[Aqueous solution]
The tubular structure obtained by the present invention is characterized in that the aqueous solution does not remain at all on the inner wall in a state where the aqueous solution is flowed, and does not require any cleaning after use. As the aqueous solution, an aqueous solution containing a water-soluble inorganic compound, particularly, a metal ion can be suitably used.

  As the aqueous solution, an aqueous solution containing a water-soluble organic dye, a water-soluble amino acid, a water-soluble saccharide, a water-soluble vitamin, a water-soluble protein, DNA, a water-soluble drug and the like can also be used. Furthermore, even an aqueous solution containing a water-soluble organic compound, for example, an alcohol compound containing a hydroxyl group, an organic acid compound containing a carboxylic acid group, an amine compound containing an amino group, an amide compound, etc. can be suitably used.

  Hereinafter, the present invention will be described in more detail with reference to examples. Unless otherwise specified, “%” represents “mass%”.

[Shape analysis of nanostructures by scanning electron microscope]
The isolated and dried nanostructure was fixed to a sample support with a double-sided tape, and observed with a surface observation device VE-9800 manufactured by Keyence.

[Measurement of the contact angle of water droplets on the tube inner surface]
The contact angle of water on the inner wall surface of the tubular substrate was measured from an image diagram of a high-speed camera (MotionPro X4, Integrated Design Tools, Inc.) when a water droplet moves in the tube.

[Measurement of contact angle of water droplets on the surface of glass sheet]
The contact angle of the glass surface having a superhydrophobic surface was measured with a contact angle measuring device manufactured by OCA20, DataPhysics, Germany.

Synthesis example 1
<Synthesis of linear polyethyleneimine (L-PEI)>
3 g of commercially available polyethyloxazoline (number average molecular weight 50,000, average polymerization degree 5,000, manufactured by Aldrich) was dissolved in 15 mL of 5 mol / L hydrochloric acid. The solution was heated to 90 ° C. in an oil bath and stirred at that temperature for 10 hours. Acetone 50 mL was added to the reaction solution to completely precipitate the polymer, which was filtered and washed three times with methanol to obtain a white polyethyleneimine powder. When the obtained powder was identified by ¹ H-NMR (heavy water, manufactured by JEOL Ltd., AL300, 300 MHz), the peak derived from the side chain ethyl group of polyethyloxazoline was 1.2 ppm (CH ₃ ) and 2. It was confirmed that 3 ppm (CH ₂ ) disappeared completely. That is, it was shown that polyethyloxazoline was completely hydrolyzed and converted to polyethyleneimine.

  The powder was dissolved in 5 mL of distilled water, and 50 mL of 15% aqueous ammonia was added dropwise to the solution while stirring. The mixture was allowed to stand overnight, and then the precipitated polymer aggregate powder was filtered, and the polymer aggregate powder was washed three times with cold water. The crystal powder after washing was dried in a desiccator at room temperature to obtain linear polyethyleneimine (L-PEI). The yield was 2.2 g (including crystal water). In polyethyleneimine obtained by hydrolysis of polyoxazoline, only the side chain reacts and the main chain does not change. Therefore, the polymerization degree of L-PEI is the same as 5,000 before hydrolysis.

Example 1 [Tubular structure with superhydrophobic surface]
Polymer L-PEI obtained in Synthesis Example 1 was added to distilled water and heated to 90 ° C. to prepare a 4% aqueous solution. After connecting a glass pipette made of soda lime (inner diameter 6 mm, length 5 cm) and a syringe with a rubber tube, and sucking the heated polymer aqueous solution up to a certain standard in the glass tube, it was allowed to stand for 30 seconds. The polymer aqueous solution was discharged by a pushing force of a syringe. By this operation, an L-PEI polymer layer was formed on the inner wall of the glass tube. The glass tube was allowed to stand at room temperature for 5 minutes, and then the glass tube was immersed in 20 mL of a silica source solution of MS51 / water (volume ratio 1/1) for 30 minutes. After the glass tube was taken out and the inner wall of the glass tube was washed with ethanol, it was dried at room temperature. After this operation, a light blue reflected color was seen on the glass tube.
MS51: Tetramethoxysilane tetramer (Colcoat)

  The glass tube end obtained through the above process was slightly crushed, and the fragments were observed with SEM. FIG. 1 shows the results of SEM photographs of the inner surface of the glass tube. On the inner wall, a dense array film having nanofibers as a unit structure was formed. The glass pipette obtained by the above method was added to a mixed solution prepared with 3 mL of 20% strength decyltrimethoxysilane (DTMS) chloroform solution, 30 mL ethanol, 0.6 mL aqueous ammonia (concentration 28%) at room temperature for 24 hours. Soaked. The pipette was taken out, the surface was washed with ethanol, and dried while flowing nitrogen gas. The pipette thus obtained was fixed at an inclination of 27 °, and when 80 μL of water droplet was dropped therein, the water droplet flowed out of the tube instantly. When the flow of water droplets was observed with an ultra-high speed camera (FIG. 2), the water droplets flowed in a round shape in a circular shape. At this time, the speed of water droplet flow was 55.2 cm / sec. When the water droplets in the high-speed camera photograph flow, that is, the instantaneous contact angle in the dynamic process was calculated by the method of FIG. 2-3, it was 175 °. The static contact angle on the film prepared on the surface of the sheet glass by the same method was 179.6 °.

[Movement of sodium chloride aqueous solution using tubular structure with superhydrophobic surface]
Using this pipette exhibiting superhydrophobicity, a 10% sodium chloride aqueous solution migration test was performed. Each time, a solution having a constant weight (unit of several tens of mg) was sucked, the solution was transferred to another glass tube, and the change in the weight of the liquid accompanying the solution movement was examined. Even when the solution was transferred 20 times, the weight of the transferred solution did not change at all. That is, when a pipette having a superhydrophobic inner wall was used, the sucked solution could be completely transferred without any loss such as adhesion in the pipette.

  As a comparison, when a similar test was performed with an ordinary pipette, droplets always adhered and remained on the inner wall of the pipette after the solution was moved, and the remaining amount corresponded to 2 wt% of the sucked solution.

  This result suggests that a pipette having a superhydrophobic inner wall surface does not need to be washed even after transport of an aqueous sodium chloride solution and can be used repeatedly as it is.

Example 2 [Tubular structure whose inner wall of glass tube is made of superhydrophobic surface]
In the same manner as in Example 1, a polymer layer was formed on the inner wall of the pipette and then immersed in a silica source solution for 30 minutes to form a coating made of silica nanofibers in a glass pipette tube.

  This glass tube was baked at 500 ° C. for 1 hour to remove the polymer in the inner wall coating, and then 3 mL of 20% decyltrimethoxysilane (DTMS) in chloroform, 30 mL ethanol, 0.6 mL of ammonia water (concentration) 28%) was immersed for 24 hours at room temperature. The pipette was taken out, the surface was washed with ethanol, and dried while flowing nitrogen gas. The pipette thus obtained was fixed at an inclination of 27 °, and the instantaneous contact angle in the dynamic process of water droplets flowing through the pipette was calculated in the same manner as in Example 1 and found to be 176 °.

[Movement of copper nitrate aqueous solution using tubular structure with superhydrophobic surface]
Into the pipette obtained in Example 2, 2 mL of 20 wt% aqueous copper nitrate solution was sucked and allowed to stand at room temperature for 1 hour, and then the sucked solution was extruded. At this time, no water droplets remained on the inner wall of the pipette. The inner wall of the pipette was washed with 1 mL of distilled water, the washings were collected and a drop of ethylenediamine was added, and then the absorption spectrum was measured. No absorption derived from copper ions was observed.

  For comparison, a normal pipette was used and the same experiment was performed. From the liquid after washing, strong absorption derived from copper ions appeared at 625 nm.

  FIG. 3 shows a digital photograph of the collected liquid, and FIG. 4 shows a UV-Vis spectrum. The above results strongly suggest that no copper ions remain even when a high concentration aqueous copper nitrate solution is passed through a pipette having a superhydrophobic inner wall surface.

Example 3 [Transfer of Cobalt Nitrate Aqueous Solution Using Tubular Structure with Inner Wall of Glass Tube Needless to Clean Made of Superhydrophobic Surface]
Using a superhydrophobic pipette obtained in the same manner as in Example 2, 2 mL of a 20 wt% cobalt nitrate aqueous solution was sucked and allowed to stand at room temperature for 1 hour, and then the sucked solution was extruded. At this time, no water droplets remained on the inner wall of the pipette. The inner wall of the pipette was washed with 1 mL of distilled water, the washings were collected and a drop of ethylenediamine was added, and then the absorption spectrum was measured. No absorption derived from cobalt ions was observed.

  For comparison, a normal pipette was used and the same experiment was performed. From the liquid after washing, absorption derived from cobalt ions appeared widely over 300 to 800 nm. FIG. 5 shows a UV-Vis spectrum.

Example 4 [Tubular structure with inner surface of glass tube made of superhydrophobic surface]
Up to the firing treatment, the same method as in Example 2 was performed. The pipette after the baking treatment was added to a mixed solution prepared with 3 mL of 20% strength 3-heptafluoropropyloxypropyltrimethoxysilane in chloroform, 30 mL ethanol, 0.6 mL aqueous ammonia (concentration 28%) at room temperature. Soaked for hours. The pipette was taken out, the surface was washed with ethanol, and dried while flowing nitrogen gas. The pipette thus obtained was fixed at an inclination of 27 °, and the instantaneous contact angle in the dynamic process of water droplets flowing through the pipette was calculated in the same manner as in Example 1, and found to be 178 °.

[Transfer of organic dye aqueous solution using tubular structure with superhydrophobic surface]
Into the pipette obtained in Example 4, 2 mL of an aqueous solution of 0.5 wt% tetra (p-sulfonic acid phenyl) porphyrin was sucked and allowed to stand at room temperature for 1 hour, and then the sucked solution was extruded. At this time, no water droplets remained on the inner wall of the pipette. The inner wall of the pipette was washed with 2 mL of distilled water, and the washing solution was collected and the absorption spectrum was measured. No absorption derived from tetra (p-sulfonic acid phenyl) porphyrin was observed.

  For comparison, a normal pipette was used and the same experiment was performed. From the washed liquid, strong absorption derived from tetra (p-sulfonic acid phenyl) porphyrin appeared at 440 nm. The above results strongly suggest that no dye remains even when an organic dye aqueous solution is passed through a pipette having a superhydrophobic inner wall surface.

  The tubular structure for aqueous solution transfer provided by the present invention does not attach any aqueous solution to the inner wall of the tubular structure. Therefore, the microchannel, microreactor, aqueous solution transport / transfer device, blood circulation device, precision analysis measurement device It can be applied to a wide range of fields such as medical equipment, industry and medicine.

Claims (6)

A tubular structure in which the inner wall surface of the tubular solid substrate (X) is coated with a superhydrophobic coating,
A tubular structure for moving aqueous solution, wherein the superhydrophobic coating is composed of a nanostructure (Y) formed by bonding a hydrophobic group (C) to silica nanofiber (B). The tubular structure for moving an aqueous solution according to claim 1, wherein the silica nanofiber (B) has a thickness in the range of 10 to 200 nm, a length in the range of 50 nm to 2 µm, and an aspect ratio of 2 or more. The hydrophobic group (C) is an alkyl group having 1 to 22 carbon atoms and an aromatic group which may have a substituent (as the substituent, an alkyl group having 1 to 22 carbon atoms, a fluorinated alkyl group, A hydrophobic group such as a partially fluorinated alkyl group), one or more hydrophobic groups selected from the group consisting of a fluorinated alkyl group having 1 to 22 carbon atoms and a partially fluorinated alkyl group having 1 to 22 carbon atoms. Item 3. The tubular structure for moving an aqueous solution according to Item 1 or 2. The tubular structure for moving an aqueous solution according to any one of claims 1 to 3, wherein the tubular solid substrate (X) is made of glass or plastic. A step of bringing the inner wall of the tubular solid substrate (X) into contact with a solution containing the polymer (A) having a polyethyleneimine skeleton (a) to form a polymer layer on the inner surface of the tubular solid substrate (X) ( 1) and
The tubular solid substrate (X) having the polymer layer obtained above is brought into contact with the silica source liquid (B ′), and silica nanofibers (B) are placed in the polymer layer on the inner surface of the tubular solid substrate (X). Generating (2),
A step (3) of treating the silica nanofiber (B) on the inner surface of the tubular solid substrate (X) obtained in the step (2) with a silane coupling agent (C ′) having a hydrophobic group;
The manufacturing method of the tubular structure for aqueous solution movement characterized by having. A step of bringing the inner wall of the tubular solid substrate (X) into contact with a solution containing the polymer (A) having a polyethyleneimine skeleton (a) to form a polymer layer on the inner surface of the tubular solid substrate (X) ( 1) and
The tubular solid substrate (X) having the polymer layer obtained above is brought into contact with the silica source liquid (B ′), and silica nanofibers (B) are placed in the polymer layer on the inner surface of the tubular solid substrate (X). Generating (2),
A step of firing the tubular solid substrate (X) whose inner surface is coated with the silica nanofiber (B) obtained in the step (2) and heating and removing the polymer (A) having the polyethyleneimine skeleton (a). (3 ')
A step (4) of treating the silica nanofiber (B) on the inner surface of the tubular solid substrate (X) after firing obtained in the step (3 ′) with a silane coupling agent (C ′) having a hydrophobic group; ,
The manufacturing method of the tubular structure for aqueous solution movement characterized by having.