JP2009149759A - Preparation of cationic organic-inorganic composite hydrogel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preparation of a novel organic-inorganic composite hydrogel having not only high dynamic physical properties but also low water swellable properties. <P>SOLUTION: The preparation of an organic-inorganic composite hydrogel with a three-dimensional network of the sodium pyrophosphate-containing water swellable clay mineral (B) and an organic polymer (A) obtained by copolymerization of a (meth)acrylamide or a derivative thereof and a polymerizable monomer having a quaternary ammonium base, comprises a step of preparing a homogeneous solution containing a (meth)acrylamide or a derivative thereof, a sodium pyrophosphate-containing water swellable clay mineral (B) and water (C), and adding a polymerizable monomer having a quaternary ammonium base simultaneously with a polymerization initiator or after addition of a polymerization initiator. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polymer gel used in the fields of medicine, architecture, civil engineering, machinery, transportation, electronic components, sewing, household goods, sanitary goods, agriculture, foods, and the like.

  It is known that (meth) acrylamide hydrogel exhibits better hydrophilicity than silicon gel and urethane gel, but is weak in mechanical strength and difficult to handle. Various efforts have been made to improve the mechanical strength. For example, as a method for greatly improving the mechanical properties of (meth) acrylamide hydrogels, the polymerization of (meth) acrylamide derivatives is carried out in the presence of clay minerals that are uniformly dispersed in water. An organic-inorganic composite hydrogel having a breaking strength has been found (Patent Document 1). Due to such improvement in mechanical strength, the practicality of these gels has become realistic. On the other hand, in order to meet various needs, it is desired to further improve or impart functionalities such as water swell resistance, antibacterial properties, and metal scavenging properties to the hydrogel as well as mechanical properties.

  Patent Document 2 discloses a technique related to an organic-inorganic composite hydrogel produced by polymerization of an acrylamide monomer in the presence of clay, and describes that an acrylamide derivative and a monomer having a quaternary ammonium base can be copolymerized. . However, this document does not disclose details of a method for stably producing an organic-inorganic composite hydrogel using a monomer having a quaternary ammonium base.

JP 2002-053629 A JP 2006-169314 A

  An object of the present invention is to provide a stable production method of an organic-inorganic composite hydrogel having not only high mechanical properties but also cationic properties.

  The present inventors have intensively studied to solve the above problems. As a result, using a sodium pyrophosphate-containing water-swellable clay mineral, a polymerizable monomer having a (meth) acrylamide derivative and a quaternary base, a sodium pyrophosphate-containing water-swellable clay mineral (B), and water (C) An organic-inorganic composite hydrogel having cationic properties is obtained by effectively lowering the viscosity of the homogeneous mixed solution and allowing copolymerization of a (meth) acrylamide derivative and a polymerizable monomer having a quaternary ammonium base, The present inventors have found that the above problems can be solved and have completed the present invention.

  That is, the present invention is a method for producing an organic-inorganic composite hydrogel in which an organic polymer (A) and a sodium pyrophosphate-containing water-swellable clay mineral (B) form a three-dimensional network, After preparing a homogeneous solution containing acrylamide or a derivative thereof, the sodium pyrophosphate-containing water-swellable clay mineral (B), and water (C), a polymerizable monomer having a quaternary ammonium base is used simultaneously with the polymerization initiator. Alternatively, the organic polymer (A) is produced by copolymerizing the (meth) acrylamide or a derivative thereof and the polymerizable monomer having a quaternary ammonium base in addition to the addition of a polymerization initiator. A method for producing a cationic organic-inorganic composite hydrogel is provided.

  The present invention also provides an organic-inorganic composite hydrogel in which an organic polymer (A) and a sodium pyrophosphate-containing water-swellable clay mineral (B) form a three-dimensional network, the organic polymer (A ) Is a copolymer of (meth) acrylamide or a derivative thereof and a polymerizable monomer having a quaternary ammonium base, to provide a cationic organic-inorganic composite hydrogel.

  According to the production method of the present invention, an organic-inorganic composite hydrogel having a cationic property can be produced stably. And the hydrogel manufactured by this invention has the high mechanical physical property of organic-inorganic composite hydrogel, and has the mechanical strength outstanding compared with the conventional organic bridge | crosslinking hydrogel. In addition, by introducing a polymerizable monomer having a quaternary ammonium base into the molecular chain, a hydrogel having low water swellability can be obtained, and it has become possible to develop applications as a biomaterial, for example, an artificial breast implanted in the body. . Moreover, since it shows cationic property, functionality, such as antibacterial property and metal scavenging property, is expected.

  The organic polymer (A) used in the present invention is obtained by copolymerization of a polymerizable monomer having a quaternary ammonium base and (meth) acrylamide and / or a derivative thereof, and is sodium pyrophosphate dispersed in water A three-dimensional network is formed by the water-swellable clay mineral (B) and noncovalent bonds such as hydrogen bonds and ionic bonds.

  The (meth) acrylamide or its derivatives constituting the organic polymer (A) includes N-substituted acrylamide derivatives, N, N-disubstituted acrylamide derivatives, N-substituted methacrylamide derivatives, N, N-disubstituted methacrylamide derivatives. Etc. Specifically, acrylamide, N-methylacrylamide, N-ethylacrylamide, N-cyclopropylacrylamide, N-isopropylacrylamide, methacrylamide, N-methylmethacrylamide, N-cyclopropylmethacrylamide, N-isopropylmethacrylamide, N, N-dimethylacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-isopropylacrylamide, N-methyl-Nn-propylacrylamide, N, N-diethylacrylamide, N-acryloylpyrrolidine, N-acryloyl Examples include piperidin, N-acryloylmethyl homopiperazine, N-acryloylmethylpiperazine and the like. Among them, N-isopropylacrylamide, N, N-diethylacrylamide, and the like having polymer properties (hydrophilicity and hydrophobicity) in an aqueous solution having LCST (lower critical solution temperature) are preferably used from the viewpoint of functionality.

  In addition, the polymerizable monomer having a quaternary ammonium base constituting the organic polymer (A) brings cationicity to the organic-inorganic composite hydrogel, and the following monomers are preferably used.

  Dimethylaminopropylacrylamide quaternary salt, dimethylaminoethyl methacrylate quaternary salt, diethylaminoethyl methacrylate quaternary salt, dimethylaminoethyl acrylate quaternary salt, diethylaminoethyl acrylate quaternary salt, 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride Etc.

  The sodium pyrophosphate-containing water-swellable clay mineral (B) used in the present invention is one that swells in water and can be uniformly dispersed, and particularly preferably can be uniformly dispersed in water at a molecular level (single layer) or a level close thereto. It is a layered clay mineral. For example, water-swellable smectite or water-swellable mica is used. Specifically, water-swellable hectorite containing sodium as an interlayer ion, water-swellable montmorillonite, water-swellable saponite, water-swellable synthetic mica, etc. Can be mentioned. These clay minerals need to be finely and uniformly dispersed in an aqueous solution before the monomer of the water-soluble organic polymer is polymerized. In particular, the clay mineral must be dispersed at the unit layer level in the aqueous solution. desirable. Here, it is necessary that there is no clay mineral aggregate that causes precipitation of clay mineral in the aqueous solution, more preferably one having a thickness of about 1 to 10 layers dispersed, particularly preferably 1 or It is dispersed with a thickness of about two layers.

  It is necessary to add sodium pyrophosphate to the above clay mineral. By adding sodium pyrophosphate, the viscosity of the clay mineral aqueous dispersion is effectively lowered, and even at high concentrations, the organic polymer monomer can be uniformly polymerized without gelation. When a monomer having a quaternary ammonium base is used, when an ordinary untreated clay mineral not added with sodium pyrophosphate-containing water-swellable clay mineral is used, an ion exchange reaction between the ammonium cation and the clay mineral is performed. Occurs, the clay mineral is hydrophobized and loses its interaction with the acrylamide derivative. Therefore, when the content rate of untreated clay mineral becomes low, the amount of unreacted clay mineral decreases, and a composite hydrogel having mechanical strength cannot be obtained. On the other hand, when the content of the untreated clay mineral is increased, the solution is gelled when the quaternary salt monomer is added, and the monomer cannot be uniformly dispersed or copolymerized. Moreover, when the monomer is dispersed in the gelled solution using a stirrer, the reaction between the monomer having a quaternary ammonium base and the untreated clay mineral is accelerated by strong stirring, and the clay mineral as an inorganic crosslinking agent is accelerated. It lost its function and no strong composite hydrogel was obtained. By using sodium pyrophosphate, the solution does not gel even in a high concentration clay mineral aqueous solution, and the copolymerization of the (meth) acrylamide derivative and the polymerizable monomer having a quaternary ammonium base can be made uniform. .

  The ratio of the organic polymer (A) in the cationic organic-inorganic composite hydrogel of the present invention to the water-swelling clay mineral (B) containing sodium pyrophosphate that can be uniformly dispersed in water is important, preferably the pyrophosphoric acid The mass ratio ((B) / (A)) of the sodium-containing water-swellable clay mineral (B) and the organic polymer (A) is 0.05-5. More preferably, the mass ratio of (B) / (A) is 0.1 to 4, particularly preferably 0.2 to 3.

  When the mass ratio of (B) / (A) is less than 0.05, the stretchability of the hydrogel of the present invention is often insufficient, and when it exceeds 5, problems in production such as the resulting hydrogel become brittle There is a case. On the other hand, the ratio of (C) water to (A) + (B) can be arbitrarily set within a wide range according to the purpose by adjusting the amount of water in the polymerization process or by subsequent swelling or drying.

  Further, in the monomer composition of the organic polymer (A), if the copolymerization ratio of the polymerizable monomer having a quaternary ammonium base is too high, the mechanical properties of the obtained hydrogel are lowered. On the other hand, if the copolymerization ratio is too low, the low water absorption of the hydrogel of the present invention cannot be obtained. Accordingly, the copolymerization ratio of the polymerizable monomer having a quaternary ammonium base in the organic polymer (A) is preferably 0.1 to 30 mol%, more preferably 0.2 to 25 mol%, based on the whole monomer. And particularly preferably 0.3 to 20 mol%, and most preferably 0.5 to 15 mol%.

  The organic-inorganic composite hydrogel having cationic property of the present invention has a critical temperature (Tc) that is transparent and / or volume swelled on the low temperature side and opaque and / or volume contracted on the high temperature side, and Tc Including those having the feature that the volume can be reversibly changed by the temperature change above and below the boundary. Such an organic-inorganic composite hydrogel can be prepared using an organic monomer exhibiting LCST (lower critical solution temperature) in an aqueous solution as an organic monomer.

  The organic-inorganic composite hydrogel having a cationic property of the present invention retains the characteristics of the organic-inorganic hydrogel, and exhibits excellent mechanical properties and the like in addition to having a low water absorption rate as compared with conventional organic crosslinked gels. For example, the organic-inorganic composite hydrogel having a cationic property in mechanical properties such as strength, elongation, and toughness is all superior to the organic crosslinked gel.

Since the mechanical properties of the organic-inorganic composite hydrogel vary depending on the water content and shape of the hydrogel, the mechanical properties of the organic-inorganic composite hydrogel having a cationic property according to the present invention include those having a water content and a cross-sectional area within a certain range. It is represented by the result of using and testing. In the present specification, specifically, a hydrogel having a cross-sectional area (initial cross-sectional area) of 0.2 to 0.5 cm ² at the start of the test is used as a test material, and the water in the organic-inorganic composite hydrogel having a cationic property is used. The mechanical properties of (C) having a content (water content) of 90% by mass were measured.

  The organic-inorganic composite hydrogel having a cationic property according to the present invention has a tensile strength of 10 to 500 kPa, more preferably 20 to 450 kPa, particularly when measured using the hydrogel having the above water content and initial cross-sectional area. It is preferably 30 to 400 kPa, and further, the tensile elongation at break is 100 to 3000%, more preferably 200 to 2500%, and particularly preferably 300 to 2000%.

  In the organic-inorganic composite hydrogel having a cationic property according to the present invention, the equilibrium swelling degree Wgel / Wdry of water is preferably 100 or less. Here, the equilibrium swelling degree Wgel / Wdry is the mass number of the hydrogel swollen per 1 g of the dried gel. Wdry is the solid content of the hydrogel, and Wgel is the mass until the hydrogel is soaked in a large amount of water and does not increase its weight. The equilibrium swelling degree Wgel / Wdry is more preferably 5 to 150, and particularly preferably 10 to 100.

  The organic-inorganic composite hydrogel having a cationic property of the present invention can be produced by the following method. After preparing a uniform solution containing a (meth) acrylamide derivative, a sodium pyrophosphate-containing water-swellable clay mineral (B) that can be uniformly dispersed in water, and water (C), the layer-exfoliated sodium pyrophosphate-containing water-swelling property Polymerization of the monomer of the organic polymer (A) is carried out in the presence of the clay mineral (B). Crosslinking agent of sodium pyrophosphate-containing water-swellable clay mineral (B) by the interaction of acrylamide derivative, which is a monomer of organic polymer (A), and sodium pyrophosphate-containing water-swellable clay mineral (B) during the polymerization process The organic polymer (A) and the sodium pyrophosphate-containing water-swellable clay mineral (B) are combined at the molecular level, and the organic polymer has a cationic property that gels by forming a three-dimensional network. An inorganic composite hydrogel is obtained.

  Specifically, a (meth) acrylamide derivative is added to an aqueous solution of sodium pyrophosphate-containing water-swellable clay mineral (B) finely dispersed in water, and radical polymerization is initiated with a polymerizable monomer having a quaternary ammonium base at low temperature. An agent is added, followed by polymerization at a predetermined temperature. Here, the addition order of the polymerizable monomer having a quaternary ammonium base is important. When a polymerizable monomer having a quaternary ammonium base is added together with the acrylamide derivative first, precipitation occurs due to an ion exchange reaction between the clay mineral and the quaternary ammonium base, and a uniform hydrogel cannot be obtained. In order to minimize sedimentation of clay minerals, (meth) acrylamide (derivative) is first added to the clay mineral aqueous dispersion, followed by the addition of a polymerizable monomer having a quaternary ammonium base and a polymerization initiator at once. Alternatively, after adding a polymerization initiator, by adding a polymerizable monomer having a quaternary ammonium base, radical polymerization is performed together with the dispersion of the monomer, and the entire system is gelled effectively. When adding a polymerization initiator and a polymerizable monomer having a quaternary ammonium base separately, it is preferable to add the monomer immediately after adding the polymerization initiator. When the polymerization initiator is added, polymerization of (meth) acrylamide (derivative) previously added to the aqueous dispersion starts. Therefore, when a polymerization initiator is added, it is preferable to add a polymerizable monomer having a quaternary ammonium base as soon as possible to promote random copolymerization and exert the effects of the present invention.

  The above radical polymerization reaction can be performed by a known method such as radical polymerization initiator and / or radiation irradiation. As the radical polymerization initiator and the catalyst, known and commonly used radical polymerization initiators and catalysts can be appropriately selected and used. Preferably, those having water dispersibility and uniformly contained in the entire system are used.

  Specifically, as a polymerization initiator, water-soluble peroxides such as potassium peroxodisulfate and ammonium peroxodisulfate, water-soluble azo compounds such as VA-044, V-50, V-501, And water-soluble radical initiators having an ethylene oxide chain. On the other hand, as the catalyst, tertiary amine compounds such as N, N, N ′, N′-tetramethylethylenediamine and β-dimethylaminopropionitryl are used.

  The polymerization temperature can be set in the range of 0 ° C. to 100 ° C. according to the type of initiator. The polymerization time varies depending on other polymerization conditions, and is generally carried out for several tens of seconds to several tens of hours.

  The invention is further illustrated by the following examples.

(Measurement condition)
In the following Examples and Comparative Examples, the tensile test was performed using an unpurified round bar-shaped hydrogel (diameter = 5.5 mm) or a flat plate-shaped hydrogel (Shimadzu Corporation) using a tabletop universal testing machine AGS-H. (Width = 10 mm, thickness = 4.5 mm) was mounted on a tensile tester without slipping at the chuck portion, and measurement was performed at a distance between gauge points = 30 mm and a pulling speed = 100 mm / min. The degree of water swelling was determined from the time dependence of the mass increase of about 0.2 g of a round rod-shaped hydrogel having a diameter of 5.5 mm immersed in a large amount of water.

(reagent)
・ Clay minerals
XLS: 6% sodium pyrophosphate water-swelling synthetic hectorite (Trademark Laponite XLS, manufactured by Nippon Silica Co., Ltd.)
XLG: Water-swellable synthetic hectorite (Trademark LAPONITE XLG, manufactured by Nippon Silica Co., Ltd.)
·monomer
DMAA: Used after removing the polymerization inhibitor using dimethylacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) and activated alumina.
NIPAM: N-isopropylacrylamide (manufactured by Kojin Co., Ltd.), recrystallized using a mixed solvent of toluene and hexane and purified into colorless needle crystals before use.
DMAPAA-Q: quaternary salt of dimethylaminopropylacrylamide, 79% aqueous solution (manufactured by Kojin Co., Ltd.)
DMAEA-Q: quaternary salt of dimethylaminoethyl acrylate, 75% aqueous solution (manufactured by Kojin Co., Ltd.)
Bremma QA: 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride, 50% aqueous solution (manufactured by NOF Corporation)
BIS: N, N'-methylenebisacrylamide (manufactured by Kanto Chemical Co., Inc.)
・ Polymerization initiator
KPS: potassium peroxodisulfate (manufactured by Kanto Chemical Co., Inc.), diluted with pure water at a ratio of KPS / water = 0.2 / 10 (g / g) and used as an aqueous solution.
・ Polymerization catalyst
TEMED: N, N, N ', N'-tetramethylethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.)

(Example 1 and Comparative Examples 1 and 2)
A uniform solution was prepared by stirring 19 g of pure water and 1.6 g of XLS in a flat bottom glass container having an inner diameter of 25 mm and a length of 80 mm. DMAA 1.9g was added to this, and nitrogen bubbling was carried out for 15 minutes. Subsequently, immediately after stirring and adding 1 g of KPS aqueous solution and 16 μl of TEMED in an ice bath, a transparent solution of 0.14 g of DMAPAA-Q and 1 g of pure water was added to obtain a uniform solution. The obtained uniform solution was immediately transferred to a glass tube container having an inner diameter of 5.5 mm and a length of 150 mm with a closed bottom so as not to come into contact with oxygen, and the upper part was sealed and subjected to stationary polymerization at 20 ° C. After 15 hours, a uniform rod-like hydrogel having elasticity and toughness was formed in the glass tube container. The hydrogel was purified by immersion in a large amount of water. The obtained purified hydrogel was dried at 100 ° C. under reduced pressure to obtain a dried hydrogel from which moisture was removed. It was confirmed that when the dried gel was immersed in water at 20 ° C., it returned to a stretchable hydrogel having the same shape as before drying. Also, thermogravimetric analysis (TG-DTA220 manufactured by Seiko Denshi Kogyo Co., Ltd .: raised to 600 ° C. at 10 ° C./min under air flow) was performed on the dried gel to obtain B / A = 0.8 (mass ratio). .

  From the above, the gel obtained in this example is a hydrogel composed of an organic polymer (a copolymer of N, N-dimethylacrylamide and DMAPAA-Q), a clay mineral, and water having a component ratio according to the charged composition. Even if no cross-linking agent is added in the synthesis of the organic polymer, a uniform hydrogel is obtained, and the dried gel obtained by removing water from the hydrogel is immersed again in water. It was concluded that a three-dimensional network in which organic polymers and clay minerals were combined at the molecular level was formed in water.

  The organic polymer synthesized under the same conditions except that no clay mineral coexists became a polymer aqueous solution and did not become a hydrogel.

  A tensile test was conducted on an unpurified round rod-shaped hydrogel, and the results are shown in FIG. In addition, the measurement result of water swellability is shown in FIG.

  In addition, an organic crosslinking gel having a cationic property of Comparative Example 1 was synthesized using an organic crosslinking agent instead of the clay mineral. The gel of Comparative Example 1 was extremely fragile and an attempt was made to perform a tensile test, but most of the samples were broken before being attached to the chuck. Moreover, even those lightly attached to the chuck were broken immediately after the test, and no physical property values were obtained.

  A hydrogel of Comparative Example 2 was synthesized in the same manner as Example 1 except that DMAPAA-Q was not used. In terms of water swellability, Example 1 of the hydrogel having a cationic property showed low water absorption as compared with Comparative Example 2 (FIG. 3).

(Examples 2, 3.4, 5, 6, 7)
Hydrogels having cationic properties of Examples 2, 3, 4, 5, 6, and 7 were synthesized in the same manner as in Example 1 with the compositions shown in Table 1. As shown in FIGS. 1 to 4, the hydrogels of Examples 2, 3, 4, 5, and 6 exhibited excellent mechanical properties and low water swellability.

(Example 8 and Comparative Example 3)
The cationic hydrogel of Example 8 having the composition shown in Table 1 and a low clay content was synthesized in the same manner as in Example 1. In addition, an attempt was made to make a hydrogel of Comparative Example 3 having the same composition as in Example 8 except that sodium pyrophosphate was not used. However, when DMAPAA-Q was added, the solution was significantly thickened and the DMAPAA-Q was homogeneous. Dispersion was not possible. Further, the monomer was dispersed in the gelled solution using a stirrer, but a uniform stretchable hydrogel could not be obtained. This is presumably because the reaction between the monomer having a quaternary ammonium base and the clay mineral was accelerated by vigorous stirring, and the function of the clay mineral as an inorganic crosslinking agent was lost.

It is a figure which shows the intensity | strength and elongation of the hydrogel obtained in Example 1,2,3,4,5,6. FIG. 4 is a view showing the strength and elongation of the hydrogel obtained in Examples 7 and 8. 2 is a graph showing the water swelling degree of hydrogels obtained in Examples 1, 2, 3, 4, 5 and Comparative Example 2. FIG. FIG. 4 is a graph showing the water swelling degree of the hydrogels obtained in Examples 6 and 7.

Claims (8)

A method for producing an organic-inorganic composite hydrogel in which an organic polymer (A) and a sodium pyrophosphate-containing water-swellable clay mineral (B) form a three-dimensional network, comprising (meth) acrylamide or a derivative thereof, After preparing a homogeneous solution containing the sodium pyrophosphate-containing water-swellable clay mineral (B) and water (C), a polymerizable monomer having a quaternary ammonium base is added simultaneously with a polymerization initiator or a polymerization initiator is added. In addition, the organic polymer (A) is produced by copolymerizing the (meth) acrylamide or a derivative thereof and the polymerizable monomer having the quaternary ammonium base. A method for producing a composite hydrogel. 2. The cationic organic-inorganic composite according to claim 1, wherein a mass ratio ((B) / (A)) of the sodium pyrophosphate-containing water-swellable clay mineral (B) and the organic polymer (A) is 0.05 to 5. A method for producing a hydrogel. 3. The method for producing a cationic organic-inorganic composite hydrogel according to claim 1, wherein the sodium pyrophosphate-containing water-swellable clay mineral (B) is a sodium pyrophosphate-containing synthetic hectorite. The polymerizable monomer having a quaternary ammonium base is dimethylaminopropylacrylamide quaternary salt, dimethylaminoethyl methacrylate quaternary salt, diethylaminoethyl methacrylate quaternary salt, dimethylaminoethyl acrylate quaternary salt, diethylaminoethyl acrylate quaternary salt, and The method for producing a cationic organic-inorganic composite hydrogel according to any one of claims 1 to 3, which is at least one selected from 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride. The cationic organic-inorganic composite hydrogel according to any one of claims 1 to 4, wherein a copolymerization ratio of the polymerizable monomer having the quaternary ammonium base in the organic polymer (A) is 30 mol% or less. Production method. A cationic organic-inorganic composite hydrogel obtained by the production method according to any one of claims 1 to 5, wherein the tensile strength at a time point when the content (water content) of water (C) is 90% by mass is 10 kPa. Cationic organic-inorganic composite hydrogel having ˜500 kPa and elongation at break of 100% to 2,000%. The cationic organic-inorganic composite hydrogel according to claim 6, wherein the equilibrium swelling degree Wgel / Wdry with water is 10 to 100. An organic-inorganic composite hydrogel in which an organic polymer (A) and a sodium pyrophosphate-containing water-swellable clay mineral (B) form a three-dimensional network, wherein the organic polymer (A) is a (meta) A cationic organic-inorganic composite hydrogel characterized by being a copolymer of acrylamide or a derivative thereof and a polymerizable monomer having a quaternary ammonium base.

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