JP7315949B2 - HIGH STRENGTH GEL BODY AND METHOD FOR MAKING THE SAME AND HYDROGEL AND METHOD FOR MAKING THE SAME - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Proceedings of the 67th SPSJ Annual Meeting Publisher: The Society of Polymer Science, Japan Publication date: May 8, 2018

TECHNICAL FIELD The present invention relates to a high-strength gel body and a method for producing the same. The present invention also relates to hydrogels and methods of making the same.

A gel body has a three-dimensional network structure in which polymer chains are linked by cross-linking, and exhibits properties very similar to those of living tissue due to its high water absorption and flexibility. Therefore, gel bodies are expected to be applied to biomimetic materials and the like. However, the gel body has very low mechanical strength and is easily broken by stretching or compressing several times. The breaking energy of the gel body is about 1/100 of that of a living tissue such as cartilage. Various high-strength gels have been reported to overcome this vulnerability. For example, a topological gel using polyrotaxane has been reported in which cyclic cross-linking points can move freely along the polymer chain (for example, Y. Okumura and K. Ito, Advanced Materials, 13, 485 (2001 )”, etc.). This topological gel can be stretched 10 times or more compared to gels synthesized by conventional free radical reactions . In addition, nanocomposite gels using nanoclays at cross-linking points exhibit high elongation like topological gels (see, for example, K. Haraguchi and T. Takehisa, Advanced Materials, 14, 1120 (2002)). Furthermore, a double network gel (DN gel) consisting of two types of networks can withstand stress of several tens of MPa in addition to high stretching (for example, "JP Gong, Y. Katsuyama, T. Kurokawa and Y Osad, Advanced Materials, 15, 1155 (2003)”. Such high-strength gels are expected to be applied as cartilage imitation materials and new soft materials. These high-strength gels have high mechanical properties by designing special network structures and can be made by special synthetic methods as described above.

Y. Okumura and K. Ito, Advanced Materials, 13, 485 (2001) K. Haraguchi and T. Takehisa, Advanced Materials, 14, 1120 (2002) J. P. Gong, Y. Katsuyama, T. Kurokawa and Y. Osad, Advanced Materials, 15, 1155 (2003)

An object of the present invention is to propose a novel method for producing high-strength gels. Another object of the present invention is to propose a novel method for producing a high-strength hydrogel.

A method for producing a high-strength gel body according to the first aspect of the present invention includes a gel body production step, a theoretical crosslink density calculation step, an elastic modulus measurement step, an effective crosslink density calculation step, a ratio calculation step, and a selection step. The theoretical crosslink density calculation step may be performed any time before the ratio calculation step (before the gel body preparation step), or may be performed simultaneously with other steps. In the gel body preparation step, a plurality of types of gel bodies are prepared while changing at least one of the monomer concentration and the added amount of the cross-linking agent. In the theoretical cross-linking density calculation step, the theoretical cross-linking density of each of the plurality of types of gel bodies is obtained. In the elastic modulus measuring step, the elastic moduli of each of the plurality of types of gel bodies are measured. In the effective cross-linking density calculation step, the elastic modulus is used to obtain the effective cross-linking density of each of the plurality of types of gel bodies. In the ratio calculation step, the ratio of the effective crosslink density to the theoretical crosslink density is obtained for each of the plurality of types of gel bodies. In the selection step, gel bodies having a ratio of effective crosslink density to theoretical crosslink density greater than 1 are selected.

As a result of diligent investigations by the inventors of the present application, when a plurality of types of gel bodies were produced by changing at least one of the monomer concentration and the amount of the cross-linking agent added, there was a gel body having an effective cross-linking density exceeding the theoretical cross-linking density. It has been found that such gel bodies exist and exhibit higher strength than gel bodies with effective crosslink densities equal to the theoretical crosslink density and gel bodies with effective crosslink densities below the theoretical crosslink density. Therefore, if a gel body is produced according to this method for producing a high-strength gel body, a high-strength gel can be obtained in the production of a gel body having an unknown composition.

A method for producing a high-strength gel body according to the second aspect of the present invention includes a condition selection step, a pre-gel solution preparation step, and a gel body production step. In the condition selection step, the monomer concentration and the amount of cross-linking agent added are selected so that the ratio of the effective cross-linking density to the theoretical cross-linking density of the gel body exceeds 1. In the pre-gel solution preparation step, the monomer is dissolved in the liquid to match the monomer concentration, and the amount of the cross-linking agent that matches the amount of the cross-linking agent added is dissolved in the liquid. In the gel body-producing step, the monomer and the cross-linking agent are reacted to produce a gel body.

By converting the findings obtained by the method for producing a high-strength gel according to the first aspect into data, it is possible to obtain a high-strength gel according to this method for producing a high-strength gel without screening.

A high-strength gel body according to a third aspect of the present invention comprises a polymer network body and a liquid. The polymer network is obtained by a radical reaction between a vinyl-based monomer component containing acrylamide and N,N'-methylenebisacrylamide as a cross-linking agent. A liquid is contained in the polymer network. In this high-strength gel body, the ratio of the effective crosslink density to the theoretical crosslink density exceeds 1.

As a result of intensive studies by the inventors of the present application, it was found that a gel body having an effective cross-linking density exceeding the theoretical cross-linking density is a gel body having an effective cross-linking density equal to the theoretical cross-linking density and a gel body having an effective cross-linking density lower than the theoretical cross-linking density. It was found to exhibit higher strength than

In the hydrogel production method according to the fourth aspect of the present invention, in water, a vinyl-based monomer component containing acrylamide at a concentration within the range of 2.5 mol / L or more and 5.0 mol / L or less, and the vinyl-based monomer component On the other hand, N,N'-methylenebisacrylamide as a cross-linking agent added at a concentration within the range of 0.001 mol % or more and 0.01 mol % or less is radically reacted to produce a hydrogel. Examples of monomers other than acrylamide contained in the vinyl-based monomer component include vinyl monomers capable of polymerizing with acrylamide (eg, acrylate-based monomers, methacrylate-based monomers, etc.). The acrylamide content in the vinyl-based monomer component is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, and particularly preferably 90 mol% or more. preferable. Also, the acrylamide content in the vinyl-based monomer component may be 100 mol (in such a case, the entire vinyl-based monomer component is acrylamide).

As a result of intensive studies by the inventors of the present application, it has become clear that the above hydrogel production method can produce a hydrogel that is superior in strength to a hydrogel produced with a charge concentration different from the above. In addition, in the hydrogel production method described above, a desired hydrogel can be produced by performing a radical reaction . Therefore, this hydrogel has a relatively simple structure. Therefore, in the hydrogel production method according to the present invention, a high-strength gel having a relatively simple structure can be synthesized relatively easily.

The hydrogel according to the fifth aspect of the present invention includes, in water, a vinyl-based monomer component containing acrylamide at a concentration within the range of 2.5 mol / L or more and 5.0 mol / L or less, and with respect to the vinyl-based monomer component It is formed by radical reaction with N,N'-methylenebisacrylamide as a cross-linking agent having a concentration within the range of 0.001 mol % or more and 0.01 mol % or less. Examples of monomers other than acrylamide contained in the vinyl-based monomer component include vinyl monomers capable of polymerizing with acrylamide (eg, acrylate-based monomers, methacrylate-based monomers, etc.). The acrylamide content in the vinyl-based monomer component is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, and particularly preferably 90 mol% or more. preferable. Also, the acrylamide content in the vinyl-based monomer component may be 100 mol % (in such a case, the entire vinyl-based monomer component is acrylamide).

This hydrogel is produced by a radical reaction . Therefore, this hydrogel has a relatively simple structure. Therefore, the hydrogel according to the present invention has a relatively simple structure and can be synthesized relatively easily.

FIG. 2 is a diagram plotting effective crosslink density/theoretical crosslink density versus crosslinker concentration during preparation of hydrogels according to Examples 1 to 12 and Comparative Examples 1 to 4 and 7 to 9. FIG. In the figure, the plots indicated by black circles are for the hydrogels of Examples 1 to 5 and Comparative Examples 1 to 3, and the plots indicated by gray circles are for the hydrogels of Examples 6 to 10 and Comparative Example 4. The plots indicated by open circles are those of hydrogels according to Examples 11 and 12 and Comparative Examples 5-7. 1 shows stress-strain curves when hydrogels according to Examples 1 to 5 and Comparative Examples 1 to 3 and 10 are stretched. In the figure, the stress-strain curve indicated by "a" is for the hydrogel according to Example 1, and the stress-strain curve indicated by "b" is for the hydrogel according to Example 2. , the stress-strain curve denoted by "c" is that of the hydrogel according to Example 3, the stress-strain curve denoted by "d" is that of the hydrogel according to Example 4, and "e" The stress-strain curve indicated by is that of the hydrogel according to Example 5, the stress-strain curve indicated by "f" is that of the hydrogel according to Comparative Example 1, and the stress indicated by "g" - the strain curve is that of the hydrogel according to Comparative Example 2, the stress-strain curve denoted by "h" is that of the hydrogel according to Comparative Example 3, and the stress-strain curve denoted by "z" is It is of the control sample according to Comparative Example 10. FIG. 2 is a diagram showing the effect of effective crosslink density/theoretical crosslink density on the fracture energy of hydrogels according to Examples 1 to 12 and Comparative Examples 1 to 4 and 7 to 9. FIG. In addition, in this figure, the curve when the acrylamide concentration in the monomer aqueous solution is 1.0 mol / L, the curve when the same concentration is 2.5 mol / L, and the curve when the same concentration is 5.0 mol / L The time curves are shown together. 1 shows stress-strain curves when hydrogels according to Examples 1 to 5 and Comparative Examples 1 to 3 and 10 are compressed. In the figure, the stress-strain curve indicated by "a" is for the hydrogel according to Example 1, and the stress-strain curve indicated by "b" is for the hydrogel according to Example 2. , the stress-strain curve denoted by "c" is that of the hydrogel according to Example 3, the stress-strain curve denoted by "d" is that of the hydrogel according to Example 4, and "e" The stress-strain curve indicated by is that of the hydrogel according to Example 5, the stress-strain curve indicated by "f" is that of the hydrogel according to Comparative Example 1, and the stress indicated by "g" - the strain curve is that of the hydrogel according to Comparative Example 2, the stress-strain curve denoted by "h" is that of the hydrogel according to Comparative Example 3, and the stress-strain curve denoted by "z" is It is of the control sample according to Comparative Example 10. It is a stress-strain curve when the hydrogels according to Examples 6 to 10 and Comparative Examples 4 to 6 are pulled. In the figure, the stress-strain curve indicated by "i" is for the hydrogel according to Example 6, and the stress-strain curve indicated by "j" is for the hydrogel according to Example 7. , the stress-strain curve denoted by “k” is that of the hydrogel according to Example 8, the stress-strain curve denoted by “l” is that of the hydrogel according to Example 9, and “m” The stress-strain curve indicated by is for the hydrogel according to Example 10, the stress-strain curve indicated by "n" is for the hydrogel according to Comparative Example 4, and the stress indicated by "o" The -strain curve is for the hydrogel according to Comparative Example 5 and the stress-strain curve denoted by "p" is for the hydrogel according to Comparative Example 6. It is a stress-strain curve when the hydrogels according to Examples 6 to 10 and Comparative Examples 4 to 6 are compressed. In the figure, the stress-strain curve indicated by "i" is for the hydrogel according to Example 6, and the stress-strain curve indicated by "j" is for the hydrogel according to Example 7. , the stress-strain curve denoted by “k” is that of the hydrogel according to Example 8, the stress-strain curve denoted by “l” is that of the hydrogel according to Example 9, and “m” The stress-strain curve indicated by is for the hydrogel according to Example 10, the stress-strain curve indicated by "n" is for the hydrogel according to Comparative Example 4, and the stress indicated by "o" The -strain curve is for the hydrogel according to Comparative Example 5 and the stress-strain curve denoted by "p" is for the hydrogel according to Comparative Example 6. It is a stress-strain curve when the hydrogels according to Examples 11 and 12 and Comparative Examples 7-9 are stretched. In the figure, the stress-strain curve indicated by "q" is for the hydrogel according to Example 11, and the stress-strain curve indicated by "r" is for the hydrogel according to Example 12. , the stress-strain curve denoted by “s” is that of the hydrogel according to Comparative Example 7, the stress-strain curve denoted by “t” is that of the hydrogel according to Comparative Example 8, and “u” The stress-strain curve indicated by is that of the hydrogel according to Comparative Example 9. It is a stress-strain curve when compressing the hydrogels according to Examples 11 and 12 and Comparative Examples 7-9. In the figure, the stress-strain curve indicated by "q" is for the hydrogel according to Example 11, and the stress-strain curve indicated by "r" is for the hydrogel according to Example 12. , the stress-strain curve denoted by "s" is that of the hydrogel according to Comparative Example 7, the stress-strain curve denoted by "t" is that of the hydrogel according to Comparative Example 8, and "u" The stress-strain curve indicated by is that of the hydrogel according to Comparative Example 9. FIG. 2 is a diagram showing the effect of cross-linking agent concentration on the water content of hydrogels according to Examples 1 to 12 and Comparative Examples 1 to 9. FIG. In addition, in this figure, the curve when the acrylamide concentration in the monomer aqueous solution is 1.0 mol / L, the curve when the same concentration is 2.5 mol / L, and the curve when the same concentration is 5.0 mol / L The time curves are shown together. 1 is a stress-strain curve showing the results of subjecting the hydrogel of Example 1 immediately after production to a cyclic tensile test. In the figure, the stress-strain curve indicated by "a01" is the one at the time of the first tension of the hydrogel immediately after preparation, and the stress-strain curve indicated by "a02" is the hydrogel immediately after preparation. The stress-strain curve indicated by "a03" is the one at the time of the third tension of the hydrogel immediately after preparation, and the stress-strain curve indicated by "a04" is the time immediately after preparation. The stress-strain curve indicated by "a05" is for the 5th stretch of the hydrogel immediately after preparation. FIG. 10 is a stress-strain curve showing the results of subjecting the hydrogel immediately after preparation of Example 13 to a cyclic tensile test. FIG. In the figure, the stress-strain curve indicated by "a01u" is the one at the time of the first tension of the hydrogel immediately after preparation, and the stress-strain curve indicated by "a02u" is the hydrogel immediately after preparation. The stress-strain curve indicated by "a03u" is the time when the hydrogel was stretched for the third time immediately after preparation, and the stress-strain curve indicated by "a04u" is the time when the hydrogel was prepared immediately after preparation. The stress-strain curve indicated by "a05u" is the result of the hydrogel being stretched for the 4th time, and the hydrogel immediately after preparation was being stretched for the 5th time. FIG. 4 is a diagram showing an example of a stress-displacement curve; FIG. 4 is a diagram conceptually showing a method of obtaining fracture energy from a stress-displacement curve.

A method for producing a high-strength gel body according to an embodiment of the present invention includes a gel body production step, a theoretical crosslink density calculation step, an elastic modulus measurement step, an effective crosslink density calculation step, a ratio calculation step, and a selection step. The theoretical crosslink density calculation step may be performed any time before the ratio calculation step (before the gel body preparation step), or may be performed simultaneously with other steps. Each step will be described in detail below.

(1) Gel Body Preparing Step In the gel body preparing step, a plurality of types of gel bodies are prepared while changing at least one of the monomer concentration and the amount of the cross-linking agent added. There are no particular restrictions on the monomers and cross-linking agents used in this step, but examples of monomers include vinyl-based monomers. Examples of vinyl-based monomers include acrylic-based monomers such as acrylamide and 2-methacryloyloxyethylphosphorylcholine, and methacrylic-based monomers. On the other hand, examples of the cross-linking agent include cross-linking agents having a plurality of vinyl groups. Examples of cross-linking agents having multiple vinyl groups include N,N'-methylenebisacrylamide.

(2) Theoretical Crosslink Density Calculation Step In the theoretical crosslink density calculation step, the theoretical crosslink density of each of the plurality of types of gel bodies is obtained. In addition, the theoretical crosslink density is obtained by the following formula (I).

In the above formula (I), “ν _theo ” represents the theoretical cross-linking density, “C” represents the cross-linking agent concentration (molar ratio of the cross-linking agent to the monomer), and “f” represents the number of functional groups of the cross-linking agent. , “Conversion” represents the conversion rate. Note that "Conversion" is 1 in the above formula (I). Also, the number of functional groups (f) of N,N'-methylenebisacrylamide is two. By the way, when the gel body has already been prepared and the monomers constituting the gel body, the cross-linking agent, and the cross-linking agent concentration are unknown, “ν _theo ” is the result of NMR measurement, IR measurement, etc. of the gel body. After identifying the monomer and the cross-linking agent from the formula (I) and deriving the cross-linking agent concentration of the gel, the number of functional groups of the cross-linking agent and the cross-linking agent concentration are substituted into the above formula (I).

(3) Elastic modulus measurement step In the elastic modulus measurement step, the elastic modulus of each of the multiple types of gel bodies is measured. In addition, it is preferable to measure a dynamic storage elastic modulus as an elastic modulus. A dynamic storage modulus can be measured, for example, using a dynamic viscoelasticity measuring device. Also, when measuring the dynamic storage modulus, it is desirable to record the temperature at the time of the measurement.

(4) Effective Crosslink Density Calculation Step In the effective crosslink density calculation step, the elastic modulus is used to obtain the effective crosslink density of each of the plurality of types of gel bodies. The effective crosslink density is determined by the following formula (II).

In the above formula (II), “ν _e ” represents the effective crosslink density (mol/m ³ ), “G” represents the elastic modulus (Pa), and “R” represents the gas constant (J/K mol ), “T” represents the absolute temperature (K) during the modulus measurement, and “v ₂ ” represents the volume fraction of the polymer in the gel body. The gas constant is 8.3144 J/K·mol. “v ₂ ” is calculated from the weight W _hg of the (water-containing) gel, the dry weight W _d of the gel, the density ρ _d of the dried gel, and the density ρ _w of water by the following formula. v ₂ = (W _d /ρ _d )/(W _d /ρ _d +(W _hg −W _d )/ρ _w )

(5) Ratio Calculation Step In the ratio calculation step, the ratio of the effective crosslink density (ν _e ) to the theoretical crosslink density (ν _theo ) for each of a plurality of types of gel bodies (that is, effective crosslink density (ν _e )/theoretical crosslink density ( ν _theo )) is required.

(6) Selection step In the selection step, a gel body having a ratio of effective crosslink density to theoretical crosslink density exceeding 1 is selected. In this step, a gel having an effective cross-linking density to theoretical cross-linking density ratio of more than 5 may be selected, a gel having a ratio of more than 10 may be selected, or a gel having a ratio of more than 50 may be selected. A body may be selected, or a gel body with a ratio greater than 100 may be selected.

By accumulating the data obtained as described above, when producing a gel body of the same type, the ratio of the effective crosslink density to the theoretical crosslink density of the gel body exceeds 1. The monomer concentration and the amount of crosslinker added A desired high-strength gel can be produced by selecting a combination of

EXAMPLES The present invention will now be described in more detail with reference to examples and comparative examples. In addition, the present invention is not limited to the following examples.

(Example 1) 1. Synthesis of hydrogel The concentration of acrylamide (hereinafter sometimes abbreviated as “AAm”) represented by the following chemical formula (A) is 5.0 mol/L, and N, N represented by the following chemical formula (B) The concentration of '-methylenebisacrylamide (hereinafter sometimes abbreviated as "MBAA") is 5.12 × 10 ^-5 mol/L, and N, N, N', Monomer by mixing AAm, MBAA, TEMED and water so that the concentration of N'-tetramethylethylenediamine (hereinafter sometimes abbreviated as "TEMED") is 4.0×10 ⁻³ mol/L. An aqueous solution was prepared (at this time, the molar ratio of MBAA to AAm (ie, crosslinker concentration) was 0.001 mol%).

Next, water was added to ammonium persulfate (hereinafter sometimes abbreviated as "APS") represented by the following chemical formula (D) to prepare an APS aqueous solution.

Subsequently, the aqueous monomer solution and the APS aqueous solution were subjected to freeze deaeration treatment to remove dissolved oxygen from the monomer aqueous solution and the APS aqueous solution. Then, a pregel solution was prepared by adding an aqueous APS solution to the aqueous monomer solution so that the concentration of APS in the aqueous monomer solution was 0.47×10 ⁻³ mol/L. Then, the pregel solution was placed in a cylindrical mold (5 mm in diameter, 5 mm in thickness) and AAm and MBAA were polymerized at a temperature of 25° C. to obtain the intended hydrogel.

2. Ratio of Effective Crosslinking Density (ν _e ) to Theoretical Crosslinking Density (ν _theo ) (1) Calculation of Theoretical Crosslinking Density The theoretical crosslinking density of the obtained hydrogel was calculated from the above formula (I). (2) Calculation of Effective Crosslink Density The effective crosslink density of the obtained hydrogel was calculated from the above formula (II). The elastic modulus (G) was measured at 25° C. using the hydrogel obtained as described above with a dynamic viscoelasticity measuring device. (3) Calculation of the ratio of the effective crosslink density to the theoretical crosslink density The effective crosslink density (ν _e ) obtained in (2) above is divided by the theoretical crosslink density obtained in (1) above to obtain the effective crosslink density relative to the theoretical crosslink density. The crosslink density ratio was found to be 75.62 (see FIG. 1, etc.).

3. Tensile test A pre-gel solution was placed in a dumbbell-shaped mold (overall thickness 1.76 mm, width of rectangular plate 5 mm, length of rectangular plate 20 mm, diameter of disc provided at both ends of rectangular plate 10 mm), and 25 AAm and MBAA were polymerized under a temperature condition of °C to obtain hydrogel specimens for tensile tests. Then, when the hydrogel test piece was subjected to a tensile test, the stress-strain curve (a) shown in FIG. 2 was obtained. This tensile test was performed using a small desktop tester EZ Test (SMTI-2-N) manufactured by Shimadzu Corporation. Furthermore, when the fracture energy was obtained from the stress-displacement curve (see FIG. 12) obtained by plotting the displacement amount on the horizontal axis and the stress on the vertical axis, the fracture energy (stress-displacement curve and The area value of the figure sandwiched between the horizontal axis (see FIG. 13)) was 24.32 kJ/m ² (see FIG. 3).

4. Compression Test When the hydrogel obtained as described above was subjected to a compression test, the stress-strain curve (a) shown in FIG. 4 was obtained. This compression test was performed with a compression force of 100 N using a small desktop tester EZ Test (SMTI-2-N) manufactured by Shimadzu Corporation.

5. Water content measurement After measuring the weight of the hydrogel obtained as described above, put the hydrogel in a dryer set at 70 ° C. and dry it for 48 hours to measure the dry weight. The water content of the hydrogel was determined. And the result was shown in FIG. (Water content) (%) = {(weight of hydrogel) - (dry weight)} / (weight of hydrogel) x 100

(Example 2) 1. Synthesis of Hydrogel A target hydrogel was obtained in the same manner as in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 2.58×10 ⁻⁴ mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.005 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, and the ratio was 13.76 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. b) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 30.38 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (b) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

6. Repeated tensile test Put the pre-gel solution into a dumbbell-shaped mold (total thickness 1.76 mm, rectangular plate width 5 mm, rectangular plate length 20 mm, disc diameter 10 mm provided at both ends of the rectangular plate). AAm and MBAA were polymerized under a temperature condition of 25° C. to obtain a hydrogel test piece for a tensile test. Then, when the hydrogel test piece was subjected to a repeated tensile test, the stress-strain curve (a01 to a05) shown in FIG. 10 was obtained. This tensile test was performed using a small desktop tester EZ Test (SMTI-2-N) manufactured by Shimadzu Corporation. Also, in this test, the hydrogel test piece was stretched three times at a speed of 5 mm/min, then the chuck on the drive side was returned to the initial position, and this cycle was repeated five times.

(Example 3) 1. Synthesis of Hydrogel A target hydrogel was obtained in the same manner as in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 5.00×10 ⁻⁴ mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.01 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 3.18 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. c) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 26.14 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (c) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 4) 1. Synthesis of Hydrogel A target hydrogel was obtained in the same manner as in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 2.57×10 ⁻³ mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.05 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, and the ratio was 4.65 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. d) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 8.79 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (d) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 5) 1. Synthesis of Hydrogel A target hydrogel was obtained in the same manner as in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 5.00×10 ⁻³ mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.1 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 1.83 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. e) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 4.06 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (e) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 1) 1. Synthesis of Hydrogel A target hydrogel was obtained in the same manner as in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 2.56×10 ⁻² mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.5 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 0.36 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. f) was obtained. Further, the fracture energy obtained from the stress-displacement curve was 0.61 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (f) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 2) 1. Synthesis of Hydrogel A desired hydrogel was obtained in the same manner as in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 5.00×10 ⁻² mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 1.0 mol %.

2. Ratio of Effective Crosslink Density (ν _e ) to Theoretical Crosslink Density (ν _theo ) When the ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, the ratio was 0.03 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. g) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 0.24 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and the stress-strain curve (g) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 3) 1. Synthesis of Hydrogel A target hydrogel was obtained as described in Example 1, except that the concentration of MBAA in preparing the aqueous monomer solution was changed to 2.44×10 ⁻¹ mol/L. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 5.0 mol %.

2. Ratio of Effective Crosslink Density (ν _e ) to Theoretical Crosslink Density (ν _theo ) When the ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, the ratio was 0.04 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. h) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 0.02 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (h) shown in FIG. 4 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 6) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 2.5×10 ⁻⁵ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.001 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, and the ratio was 166.82 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. i) was obtained. Further, the fracture energy obtained from the stress-displacement curve was 4.41 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (i) shown in FIG. 6 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 7) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 1.25×10 ⁻⁴ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.005 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, and the ratio was 62.89 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. j) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 9.84 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (j) shown in FIG. 6 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 8) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 2.5×10 ⁻⁴ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.01 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, and the ratio was 24.08 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. k) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 11.71 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (k) shown in FIG. 6 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 9) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 1.25×10 ⁻³ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.05 mol %.

2. Ratio of Effective Crosslink Density (ν _e ) to Theoretical Crosslink Density (ν _theo ) When the ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, the ratio was 2.55 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. l) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 5.22 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (l) shown in FIG. 6 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 10) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 2.5×10 ⁻³ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.1 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 5.39 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. m) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 4.65 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (m) shown in FIG. 6 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 4) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 1.25×10 ⁻² mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.5 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 0.26 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. n) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 0.16 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (n) shown in FIG. 6 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 5) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 1.25×10 ⁻² mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.5 mol %.

2. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. o) was obtained.

3. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (o) shown in FIG. 6 was obtained.

4. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 6) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 2.5 mol/L and the concentration of MBAA was changed to 1.25×10 ⁻² mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.5 mol %.

2. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. p) was obtained.

3. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and the stress-strain curve (p) shown in FIG. 6 was obtained.

4. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 11) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 1.0 mol/L and the concentration of MBAA was changed to 0.5×10 ⁻³ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.05 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 1.65 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. q) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 1.19 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (q) shown in FIG. 8 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Example 12) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 1.0 mol/L and the concentration of MBAA was changed to 1.0×10 ⁻³ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.1 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1, and the ratio was 1.71 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. r) was obtained. In addition, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 0.39 k
J/ ^m2 (see Figure 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (r) shown in FIG. 8 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 7) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 1.0 mol/L and the concentration of MBAA was changed to 0.5×10 ⁻² mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.5 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 0.61 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. s) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 0.47 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (s) shown in FIG. 8 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 8) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 1.0 mol/L and the concentration of MBAA was changed to 1.0×10 ⁻² mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 1.0 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 0.42 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. t) was obtained. Further, when the fracture energy was obtained from the stress-displacement curve, the fracture energy was 0.26 kJ/m ² (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (t) shown in FIG. 8 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 9) 1. Synthesis of Hydrogel As shown in Example 1, except that the concentration of AAm was changed to 1.0 mol/L and the concentration of MBAA was changed to 0.5×10 ⁻¹ mol/L when preparing the aqueous monomer solution. A desired hydrogel was obtained. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 5.0 mol %.

2. Ratio of effective crosslink density (ν _e ) to theoretical crosslink density (ν _theo ) The ratio of effective crosslink density to theoretical crosslink density was determined in the same manner as in Example 1 and found to be 0.09 (Fig. 1 etc.).

3. Tensile test A hydrogel test piece for a tensile test was obtained from the pregel solution of this comparative example in the same manner as in Example 1, and the hydrogel test piece was subjected to a tensile test. u) was obtained. Further, the fracture energy obtained from the stress-displacement curve was 0.06 kJ (see FIG. 3).

4. Compression Test The hydrogel obtained as described above was subjected to a compression test in the same manner as in Example 1, and a stress-strain curve (u) shown in FIG. 8 was obtained.

5. Water Content Measurement The water content of the hydrogel obtained as described above was determined in the same manner as in Example 1. And the result was shown in FIG.

(Comparative Example 10) 1. Synthesis of Control Sample The desired control sample was obtained as described in Example 1, except that no MBAA was added. At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0 mol %.

2. Tensile test A test piece for a tensile test was obtained from the monomer solution of this comparative example in the same manner as in Example 1, and the test piece was subjected to a tensile test. As a result, the stress-strain curve (z) shown in FIG. 2 was obtained. was taken.

3. Compression Test The control sample obtained as described above was subjected to compression test in the same manner as in Example 1, resulting in the stress-strain curve (z) shown in FIG.

(Example 13) 1. Synthesis of hydrogel Water was replaced with a 2 mol / L urea aqueous solution, and a cylindrical mold (diameter 5 mm, thickness 5 mm) was replaced with a dumbbell mold (total thickness 1.76 mm, rectangular plate width 5 mm, rectangular plate portion The target hydrogel was obtained as shown in Example 2, except that the length was 20 mm and the diameter of the disk portions provided at both ends of the rectangular plate portion was 10 mm). At this time, the molar ratio of MBAA to AAm (that is, the cross-linking agent concentration) was 0.005 mol %.

2. Repeated Tensile Test The hydrogel obtained in this example was subjected to a repeated tensile test in the same manner as in Example 2, and the stress-strain curves (a01u to a05u) shown in FIG. 11 were obtained.

<Summary> According to the above examples and _comparative examples, the effective _cross -linking density (ν _e )/theoretical cross-linking density (ν _theo ) of hydrogels exceeding 1 is 1. Compared to the following hydrogels, it was clarified that not only was it less likely to be broken during tension and compression, it was also superior in tensile strength and compressive strength, and had sufficiently high breaking energy. Therefore, by using effective crosslink density (ν _e )/theoretical crosslink density (ν _theo )>1 as an index, a high-strength hydrogel can be produced.

In the compression test, the hydrogel with a cross-linking agent concentration of 1.0 mol% was broken by about 70% compression, but the hydrogel with a cross-linking agent concentration of 0.001 mol% to 0.01 mol% was about 90%. It did not break even when compressed and showed good strength. Hydrogels with crosslinker concentrations of 0.001 mol % to 0.01 mol % also showed good results in tensile tests. It was also found that, when the concentration of the cross-linking agent is the same, the higher the concentration of AAm in the preparation of the aqueous monomer solution, the higher the tensile strength. This is probably because the higher the concentration of AAm during the preparation of the aqueous monomer solution, the more the molecular chains are entangled with each other, resulting in a higher energy dissipation effect.

Moreover, as shown in FIGS. 10 and 11, no hysteresis was observed in the hydrogels according to Examples 2 and 13. Also, the hydrogel according to Example 13 showed slightly better tensile strength than the hydrogel according to Example 2.

Since the method for producing a high-strength gel body according to the present invention is an unprecedented method, it is possible to provide an unprecedented high-strength gel body.

Claims (5)

a gel body preparation step of preparing a plurality of types of gel bodies while changing at least one of the monomer concentration and the added amount of the cross-linking agent;
a theoretical cross-linking density calculating step for obtaining the theoretical cross-linking density of each of the plurality of types of gel bodies;
an elastic modulus measuring step of measuring the elastic modulus of each of the plurality of types of gel bodies;
an effective cross-linking density calculating step of obtaining the effective cross-linking density of each of the plurality of types of gel bodies using the elastic modulus;
a ratio calculating step of obtaining a ratio of the effective crosslink density to the theoretical crosslink density for each of the plurality of types of gel bodies;
A method for producing a high-strength gel body, comprising a selection step of selecting a gel body in which the ratio of the effective crosslink density to the theoretical crosslink density exceeds 1. A condition selection step of selecting a monomer concentration and a cross-linking agent addition amount such that the ratio of the effective cross-linking density to the theoretical cross-linking density of the gel body exceeds 1;
A pre-gel solution preparation step of dissolving a monomer in a liquid to match the monomer concentration and dissolving an amount of a cross-linking agent in the liquid that matches the amount of the cross-linking agent added;
A method for producing a high-strength gel body, comprising a gel body-producing step of reacting the monomer and the cross-linking agent to produce a gel body. a polymer network obtained by radically reacting a vinyl-based monomer component containing acrylamide with N,N'-methylenebisacrylamide as a cross-linking agent;
a liquid contained in the polymer network;
with
The vinyl-based monomer component contains 90 mol% or more of the acrylamide,
The ratio of effective crosslink density to theoretical crosslink density is greater than 1
High strength gel body. a vinyl-based monomer component containing acrylamide at a concentration in the range of 2.5 mol/L or more and 5.0 mol/L or less in water and containing 90 mol% or more of the acrylamide ; and 0.001 mol with respect to the vinyl-based monomer component. % or more and 0.01 mol % or less, and N,N'-methylenebisacrylamide as a cross-linking agent added at a concentration within the range of 0.01 mol % or less is radically reacted to obtain a hydrogel. a vinyl-based monomer component containing acrylamide at a concentration in the range of 2.5 mol/L or more and 5.0 mol/L or less in water and containing 90 mol% or more of the acrylamide ; and 0.001 mol with respect to the vinyl-based monomer component. % or more and 0.01 mol % or less, and N,N'-methylenebisacrylamide as a cross-linking agent is radically reacted with the hydrogel.

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