JPH08311231A - Honeycomb-like porous material and its production - Google Patents

Abstract

PURPOSE: To provide an inexpensive easily producible honeycomb-like porous material and to provide a process for its production. CONSTITUTION: A linear polymer 21 is dissolved in a solvent 22, the prepared solution 20 is cooled to condense vapors such as water vapor 230 in an atmosphere and to thereby incorporate part of the liquid drops such as water drops 23 into the solution 20 from its surface. The solvent 22 is then evaporated, and the liquid drops are removed. Thus, a honeycomb-like material in which many pores 3 are formed on the surface of a base material 2 can be obtained. As the linear polymer, a linear polystyrene or the like is used. It is desirable that dichloromethane is used as the solvent. The above polymer solution may be replaced by a solution formed by feeding a solvent to the surface of a base material made of a linear polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a honeycomb porous body having a large number of pores and a method for producing the same.

[0002]

2. Description of the Related Art Honeycomb-like porous materials are used, for example, for drugs,
It is expected to be applied to capsules for biological substances, templates for synthesizing materials with ordered structure, and optical materials. As a method for manufacturing the above honeycomb-shaped porous body, for example, G.
Wideski: Nature, vol. 369,
p. 387, 1994.

This method comprises preparing a solution containing a star polymer,
By drying in the presence of water vapor with carbon disulfide as a solvent, as shown in FIG.
This is to obtain a honeycomb-shaped porous body 82 in which 0 μm pores 81 are regularly arranged on the surface of the substrate 85.

In manufacturing the above-mentioned honeycomb-shaped porous body, it is considered necessary for the polymer solution to gel at room temperature. Therefore, as the star-shaped polymer, for example, as shown in FIG. 9, a star-shaped polystyrene 72 (FIG. 9A) in which a plurality of polystyrenes 71 are bonded to each other in a central portion 710, and a plurality of polystyrenes 73 are spherical. The block copolymer 75 (FIG. 9 (b)) obtained by copolymerization via the polyparaphenylene 74 is used.

[0005]

[Problems to be Solved] However, in the production of the above-mentioned star-shaped polymer, there are drawbacks that the number of synthetic steps is large and complicated. Therefore, if the star-shaped polymer is used, the manufacturing cost of the honeycomb-shaped porous body increases.

Therefore, instead of the expensive star polymer,
It is conceivable to use an inexpensive linear polymer. However, linear polymers are described in G. A honeycomb-shaped porous body cannot be obtained by the method by Widawski (ibid., P. 387, line 35). It is considered that the reason is that the gelling temperature of the linear polymer solution is generally low, and the gelling does not occur at room temperature.

Further, it is said that a solution containing linear polystyrene, which is a kind of linear polymer, does not gel at room temperature even if carbon disulfide or dichloromethane is used as a good solvent (H. Tan: Macromolecule).
s, Vol. 16, p. 28, 1983).

Therefore, it has been conventionally considered difficult to obtain a honeycomb-shaped porous body made of a linear polymer. Therefore, the inventors conducted a sharp study in order to inexpensively and easily manufacture a honeycomb-shaped porous body. As a result, they invented a method for producing a honeycomb-shaped porous body using the above linear polymer.

In view of such conventional problems, the present invention aims to provide a honeycomb porous body which is inexpensive and easy to manufacture, and a manufacturing method thereof.

[0010]

According to a first aspect of the present invention, a linear polymer is dissolved in a solvent to prepare a polymer solution, and then the polymer solution is cooled to condense vapor in an atmosphere. A method for producing a honeycomb-shaped porous body, characterized in that a part of droplets are allowed to enter the inside of the polymer solution from the surface thereof, the solvent is then evaporated, and then the condensed droplets are removed. is there.

What is most noticeable in the present invention is that a linear polymer is used, a polymer solution containing the linear polymer is cooled so that a part of condensed liquid droplets can enter therein, and the liquid. Drops are to be removed after solvent evaporation.

In the above linear polymer, the presence or absence of side chains and the length thereof are not particularly limited as long as the main chains are linearly connected (see FIG. 2).

The weight average molecular weight (M
w) is preferably 1000 to 1,000,000. When it is less than 1000, the strength of the honeycomb porous body may not be sufficiently obtained. On the other hand, 100,000
If it exceeds 0, the polymer may not be sufficiently dissolved in the solvent.

The degree of dispersion of the above linear polymer (Mw /
Mn) is not particularly limited. The degree of dispersion (Mw / Mn) of the linear polymer is determined by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn).

The linear polymer is not particularly limited as long as it is soluble in a solvent. Examples of the linear polymer include linear polystyrene, polymethylmethacrylate, and polycarbonate. Of these, it is particularly preferable to use linear polystyrene. The reason is that there are many types of solvents for polystyrene and their solubility is high. The linear polystyrene is, for example, one in which the main chain of polystyrene is linearly connected.

The boiling point of the solvent is preferably lower than the boiling point of the liquid droplets to be condensed. The reason is that the condensed liquid droplets may evaporate as the solvent evaporates, and the pores may not be formed.

The boiling point of the solvent is preferably the same as or higher than the normal temperature. The reason is that if the temperature is lower than room temperature, it is difficult to prepare the polymer solution at room temperature. Further, the boiling point of the solvent is preferably the same as or slightly higher than normal temperature. As a result, the solvent can be rapidly evaporated at room temperature. Further, the polymer solution can be cooled by the heat of vaporization that accompanies the rapid evaporation of the solvent.

From the above, the boiling point of the solvent is 20 to 1
It is preferably 00 ° C. If the temperature is below 20 ℃,
There is difficulty in preparing a polymer solution at room temperature. On the other hand, 10
Above 0 ° C., it is necessary to expose the polymer solution to high temperatures due to evaporation of the solvent. Therefore, it is difficult to condense the vapor in the atmosphere. The lower limit is particularly preferably 30 ° C and the upper limit is 50 ° C.

The specific gravity of the solvent is preferably larger than the specific gravity of the droplet. For example, when water vapor is condensed as droplets, the specific gravity of the solvent is preferably larger than 1. The reason is that when the specific gravity of the solvent is lower than that of water, water droplets may not float on the surface of the polymer solution, and pores may not be formed on the surface.

Examples of the solvent having the above characteristics include dichloromethane and carbon disulfide. Of these, it is particularly preferable to use dichloromethane. The reason is that dichloromethane has a low boiling point. The droplet is not particularly limited as long as it does not dissolve the linear polymer and is incompatible with the solvent. The relationship between the boiling point and specific gravity of the droplet and that of the solvent is as described above.
The droplet having the above-mentioned characteristics is, for example, a water droplet.

The concentration of the linear polymer in the polymer solution before cooling is preferably 0.01 to 0.1 g / cc. If it is less than 0.01 g / cc, it may take a long time to evaporate the solvent. On the other hand, 0.1 g / c
If it exceeds c, it may be difficult to dissolve all linear polymers in a solvent.

Next, the polymer solution is cooled. The cooling temperature is lower than the boiling point of the droplet and higher than the solidification temperature of the polymer solution. As a cooling method,
For example, a method of cooling the polymer solution by heat of vaporization accompanying evaporation of the solvent, the polymer solution itself,
There is a method of cooling with a cooling means such as a refrigerator or cold water.

The cooling is performed in an atmosphere in which steam exists. As a result, the vapor in the atmosphere is condensed, and a part of the droplets enters from the surface of the polymer solution to the inside. Also, the relative partial pressure of vapor in the atmosphere varies depending on the polymer solution, the droplets to be condensed, and the cooling conditions.
It is preferably 20 to 100%. If it is less than 20%, there is a possibility that a sufficient amount of droplets for forming a porous body may not be condensed on the surface of the polymer solution.

The evaporation of the solvent can be carried out by, for example, natural drying of the solvent, forced drying by blowing an air stream, or a method of evaporating the solvent by actively heating. It is preferable to evaporate the solvent under the condition that the droplets in the polymer solution do not evaporate. This is because when the droplets evaporate prior to the solvent, pores may not be formed in the polymer solution.

The droplets in the polymer solution can be removed by, for example, blowing hot air or vacuum drying. Further, it is preferable to keep in mind that the temperature is not higher than the softening point of the linear polymer when removing the droplets. The reason is that the honeycomb porous structure may be destroyed.

Next, in the second invention of the present application, a solvent that dissolves the linear polymer is supplied to the surface of a substrate made of the linear polymer to dissolve the linear polymer, and then the linear polymer is dissolved. By cooling the solution part of the polymer and allowing the vapor in the atmosphere to condense, a part of the droplet is made to enter from the surface of the solution part of the linear polymer to the inside, and then the solvent is evaporated, and then The method for manufacturing a honeycomb-shaped porous body is characterized by removing the condensed droplets.

The above manufacturing method is different from the first invention in which a polymer solution is used in that a solvent is supplied to the surface of a substrate made of a linear polymer.

In the present invention, the substrate made of the linear polymer is not particularly limited as long as at least the surface thereof is made of the linear polymer. For example, the base material may be a linear polymer itself, or a film of the linear polymer only in the surface portion thereof, and a metal or ceramic inside thereof.

A solvent is supplied to the surface of the base material. Examples of the supply method include a method of immersing the base material in a solvent, a method of spraying the solvent with a spray, and a method of dropping the solvent with a dropper. The cooling of the linear polymer, the solvent, the solution portion of the linear polymer, the evaporation of the solvent, and the removal of the condensed droplets are preferably the same as those in the first invention described above.

Next, the honeycomb-shaped porous body produced by the first and second inventions comprises, for example, a base material made of a linear polymer and a large number of pores formed on the surface of the base material. And the pores are regularly arranged in a honeycomb shape,
There is a honeycomb porous body having a diameter of 0.2 to 10 μm.

The diameter of the pores is 0.2 to 10 μm. It is difficult to form pores having a diameter outside this range by the above manufacturing method. Further, if it is less than 0.2 μm, there is a problem that the fine pores are not arranged finely. If it exceeds 10 μm, there is a problem that the diameter of the pores becomes non-uniform.

The above-mentioned honeycomb-shaped porous body is, for example, a molecular sieve for macromolecules such as proteins, a template for inorganic fine particles, a template for synthesizing a material having an ordered structure, a drug, a capsule for bio-related substances, or an optical material. There are uses.

[0033]

In the first invention of the present application, the vapor in the atmosphere is condensed due to the cooling of the polymer solution, and a part of the droplets enters from the surface of the polymer solution.

Next, the solvent is evaporated. At the beginning of evaporation,
The concentration of linear polymer in the polymer solution is low and its viscosity is low. In this case, the droplets can move on the surface of the polymer solution and finely aggregate while growing spherically. Further, as the evaporation proceeds, the concentration of the linear polymer increases, and the viscosity increases accordingly.

Then, in the latter stage of evaporation, when the viscosity of the polymer solution exceeds a certain critical point, a base material in a state in which droplets can no longer grow or move can be obtained. Then, the droplets are removed from the base material. As a result, pores are formed in the portions of the base material where the droplets were present, and a honeycomb-shaped porous body having a porous structure is obtained.

Therefore, according to the above-mentioned manufacturing method, it is possible to obtain a honeycomb porous body by using a linear polymer which has been conventionally considered to be difficult to gel or does not gel. Moreover, since the linear polymer is easy and inexpensive to manufacture, the manufacturing cost of the honeycomb-shaped porous body can be reduced.

In the second invention of the present application, after the solvent is supplied to the surface of the base material made of the linear polymer, the base material is cooled, the solvent is evaporated, and the droplets are removed. for that reason,
Similar to the first invention, the honeycomb-shaped porous body can be easily manufactured at low cost. Further, according to the honeycomb-shaped porous body of the present invention, cost reduction can be achieved.

According to the present invention, it is possible to provide an inexpensive honeycomb-shaped porous body and a method for manufacturing the same.

[0039]

Embodiments of the present invention will be described with reference to FIGS. The honeycomb porous body 1 of this example is shown in FIG.
As shown in (1), it comprises a base material 2 made of a linear polymer and a large number of pores 3 formed on the surface of the base material 2.

The base material 2 is a polymer film having an average thickness of 20 μm. As shown in FIG. 2, the shape of the linear polymer is such that the main chains of the polymers are linearly connected. The linear polymer consists of linear polystyrene. The weight average molecular weight (Mw) of this linear polystyrene is 14,000, its number average molecular weight (Mn) is 4,800, and its dispersity (Mw / Mn) is 3.0.

The pores 3 are approximately 2.2 μm on the surface of the base material 2.
The cells are regularly arranged in a honeycomb shape at regular intervals, and their average diameter is about 1.5 μm. An optical micrograph of the surface of the polymer thin film that is the honeycomb-shaped porous body is shown in FIG. In the figure, the hexagonal black portion is the pore 3.

Next, a method for manufacturing the above honeycomb-shaped porous body will be described. First, the linear polystyrene is dissolved in dichloromethane (specific gravity: 1.32) as a solvent to prepare a polymer solution. The concentration of linear polystyrene is 0.05 g / cc.

Next, as shown in FIG. 4, the desiccator 91
A mounting table 92 is installed in the container, and a flat plate 93 is fixed thereon. The inside size of the desiccator 91 is 200 m wide.
m × depth 150 mm × height 170 mm. Flat plate 9
A base 94 is fixed to the central portion of 3, and a slide glass 95 is placed thereon. In addition, in the flat plate 93, the base 9
Distilled water 96 for keeping the inside of the desiccator at a saturated vapor pressure is put in the vicinity of 4. At the top of the desiccator 91,
Insert the rubber stopper 97. Then, the inside of the desiccator 91 is sealed, and the atmosphere therein is set to a temperature of 21 ° C. and a humidity of 100%.
Hold at RH.

Next, the above polymer solution is put into a syringe, the needle of the syringe is inserted into the rubber stopper 97, and 0.04 ml is placed on the slide glass 95 in the desiccator 91.
Polymer solution 20 of 1 is dropped and left to stand. As a result, a honeycomb-shaped porous body is formed as shown in FIG.

That is, when the polymer solution is left to stand, the solvent evaporates. Then, the heat of vaporization cools the polymer solution. Then, as shown in FIG. 5A, the water vapor 230 in the atmosphere inside the desiccator 91 is condensed,
A part of the water drops 23 enters the inside of the polymer solution 20 from the surface.

At the initial stage of evaporation of the solvent, the concentration of the linear polymer 21 in the polymer solution 20 is low and its viscosity is low. In this case, as shown in FIG. 5B, the water droplets 23 can move on the surface of the polymer solution 20 and finely aggregate while growing spherically.

Further, as the evaporation of the solvent 22 progresses, the concentration of the linear polymer 21 in the polymer solution 20 increases and its viscosity also increases. Then, when the viscosity of the polymer solution 20 exceeds a certain critical point in the latter stage of evaporation of the solvent, as shown in FIG.
As shown in (c), the base material 2 is obtained in which the water droplets 23 can no longer grow or move.

After that, the water droplets 23 partially entering the inside of the base material 2 are evaporated. As a result, the pores 3 are formed in the portions of the base material 2 where the water droplets were present. Then, as shown in FIG. 5D, the honeycomb-shaped porous body having the above-described porous structure having a large number of pores 3 on the surface of the base material 2 is formed.

Therefore, according to the above-mentioned manufacturing method, it is possible to obtain a honeycomb-shaped porous body by using a linear polymer which is conventionally considered to be difficult to gel or does not gel. Moreover, since the linear polymer is easy and inexpensive to manufacture, the manufacturing cost of the honeycomb-shaped porous body can be reduced.

Example 2 A honeycomb-shaped porous body of this example comprises a base material made of a linear polymer injection-molded substrate and a large number of pores formed on the surface portion of the base material. The linear polymer is linear polystyrene. This linear polystyrene has a weight average molecular weight (Mw) of 270000, and its number average molecular weight (Mw).
n) is 108000 and the dispersity (Mw / Mn) is 2.5.

The pores are regularly arranged in a honeycomb pattern on the surface of the base material at a period of about 5.2 μm, and the average diameter thereof is about 3.3 μm. An optical micrograph showing a fine pattern formed on the injection-molded substrate that is the above-mentioned honeycomb-shaped porous body is shown in FIG. Further, FIG. 7 shows an optical micrograph showing a fine pattern formed on the injection-molded substrate on which silica beads (average diameter 5 μm) are placed. Figure 7
In, the part of the sphere that appears white and blurred is silica beads. From the figure, it can be seen that silica beads are regularly arranged on the pores.

Next, a method for manufacturing the above honeycomb-shaped porous body will be described. First, a base material made of the injection molded plate is prepared. Next, the atmosphere (temperature 22 ℃, humidity 60
% RH), about 0.1 ml of dichloromethane as a solvent is dropped on the surface of the base material using a dropper. Subsequently, the substrate surface is dried by drafting for 3 minutes in the atmosphere. As a result, the honeycomb-shaped porous body is obtained.

In this example, a solvent is supplied to the surface of a base material made of a linear polymer to form a polymer solution portion, which is dried. During this drying, as in Example 1, phenomena such as cooling of the solution portion by evaporation of the solvent, generation of water droplets due to water vapor in the atmosphere, increase in viscosity of the solution portion, and evaporation of water droplets occur. Therefore, a honeycomb-shaped porous body having a large number of pores can be obtained in the same manner as in Example 1 above. Further, since the base material made of an inexpensive linear polymer is used, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a honeycomb-shaped porous body of Example 1.

FIG. 2 is an explanatory view of a linear polymer of Example 1.

FIG. 3 is a drawing-substitute photograph of a thin film that is a honeycomb-shaped porous body, taken by an optical microscope in Example 1.

FIG. 4 is an explanatory view showing the method for manufacturing the honeycomb-shaped porous body of Example 1.

FIG. 5 is an explanatory view of the surface portion of the base material, showing the method for manufacturing the honeycomb-shaped porous body of Example 1.

6 is a drawing-substituting photograph showing a fine pattern formed on an injection-molded substrate which is a honeycomb-shaped porous body, taken by an optical microscope, in Example 2. FIG.

FIG. 7 is a drawing-substituting photograph showing a fine pattern of a honeycomb-shaped porous body formed on an injection-molded substrate on which silica beads are placed, which is photographed by an optical microscope in Example 2.

FIG. 8 is an explanatory view showing pores of a honeycomb-shaped porous body of a conventional example.

FIG. 9 is an explanatory diagram of a star polymer of a conventional example.

[Explanation of symbols]

 1. ． ． Honeycomb-like porous body, 2. ． ． Base material, 20. ． ． Polymer solution, 21. ． ． Linear polymers, 22. ． ． Solvent, 23. ． ． Water drop, 3. ． ． pore,

Claims (4)

[Claims] 1. A linear polymer is dissolved in a solvent to prepare a polymer solution, and then the polymer solution is cooled to cause vapor in the atmosphere to condense so that a part of the liquid droplets becomes part of the polymer solution. A method for manufacturing a honeycomb-shaped porous body, characterized in that the solvent is evaporated from the surface thereof, the solvent is then evaporated, and then the condensed droplets are removed. 2. A solvent for dissolving the linear polymer is supplied to the surface of a substrate made of the linear polymer to dissolve the linear polymer, and then a solution portion of the linear polymer is cooled, Dew condensation of vapor in the atmosphere causes a part of the droplet to enter inside from the surface of the solution portion of the linear polymer, then the solvent is evaporated, and then the condensed droplet is removed. A method for manufacturing a honeycomb-shaped porous body, comprising: 3. The method for producing a honeycomb-shaped porous body according to claim 1 or 2, wherein the linear polymer is linear polystyrene. 4. A substrate comprising a linear polymer and a large number of pores formed on the surface of the substrate. The pores are regularly arranged in a honeycomb shape and have a diameter of 0.2. ~ 10μ
A honeycomb-shaped porous body characterized in that it is m.