Temperature-sensitive material and its manufacturing method

Abstract

To provide a temperature sensitive material, which prevents leakage deviation and with which various risks associated with small temperature changes are managed, and which may be produced at a small cost.SOLUTION: A temperature sensitive material 4 comprises Poly (NIPAM-co-AAC), which is a temperature-responsive polymer that undergoes a phase transition at a critical solution temperature in a solution, a gelling agent that maintains this solution in a gel form, and an indicator that changes color depending on pH. By virtue that Poly (NIPAM-co-AAC), which undergoes a phase transition at the critical solution temperature, releases or takes in hydrogen ions as a response to a temperature change within a predetermined range, the temperature sensitive material changes pH and color. The temperature sensitive material 4 is filled in an accommodation frame having a pair of transparent glass plates 2 that overlap each other with a gap and a spacer 3 that intervenes between them to form a storage space. The temperature change is made visible by color change through the glass plates 2 of the accommodation frame. The temperature sensitive material 4 is in the form of a gel, prevents leakage deviation from the accommodation frame, reduces the sealing strength, and facilitates production of a temperature sensitive display member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermosensitive material that can change color in response to changes in external temperature, using a temperature-responsive polymer that has the property of dispersing or aggregating around a specific temperature, and a method for producing the same. [Background technology]

[0002] Conventionally, the light-blocking materials described in Patent Documents 1 to 4 have been disclosed as examples of temperature-sensitive materials. These light-blocking materials utilize the property of N-isopropylacrylamide (hereinafter referred to as NIPAM) polymers, which expand in water due to their hydrophilic properties and become transparent, and contract due to their hydrophobic properties and become opaque, around a specific temperature (lower critical solution temperature (hereinafter referred to as LCST)), and are sealed together with a solvent such as an aqueous solution between transparent glass or synthetic resin plates or sheets. These light-blocking materials have been proposed for use in a wide range of fields, such as window glass plates that adjust sunlight into buildings and greenhouses. Furthermore, Patent Documents 5 to 7 disclose temperature indicating materials incorporating cholesteric liquid crystals that change color with temperature changes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 61-7948 [Patent Document 2] Japanese Patent Application Publication No. 6-330681 [Patent Document 3] Japanese Patent Application Publication No. 10-316453 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-211153 [Patent Document 5] Publication No. 60-031636 [Patent Document 6] Utility Model Registration No. 3189952 [Patent Document 7] Japanese Patent Application Laid-Open No. 2017-125741 Summary of the Invention [Problem to be solved by the invention]

[0004] When a solution of a temperature-responsive polymer is used in the above-mentioned conventional light-blocking materials, a high-strength, airtight sealing means is required to prevent leakage from the container that contains the temperature-responsive polymer and solvent, making the materials difficult to manufacture, expensive, and requiring relatively frequent maintenance and inspection. Furthermore, since only two temperature ranges are distinguished by the change between transparency and opacity around the LCST of NIPAM, it is not possible to express fine temperature changes. Cholesteric liquid crystals have a narrow color temperature range, and to overcome this, they are microencapsulated and have multiple identification positions for each display temperature, but this is difficult and expensive to produce, and the display temperature is dissipative, making it difficult to improve accuracy. Therefore, the present invention aims to provide a relatively simple and inexpensive temperature-sensitive material that inhibits fluidity, prevents leakage and deviation, allows relatively small temperature changes to be visually confirmed with high accuracy, can change the identification temperature range to expand the range of application, and can manage various risks associated with temperature changes. [Means for solving the problem]

[0005] The thermosensitive material of the present invention comprises Poly(NIPAM-co-AAC), a temperature-responsive polymer that undergoes a phase transition in a solvent at its critical solution temperature, a gelling agent that maintains the solution in a gel state, and an indicator that changes color in response to pH. Poly(NIPAM-co-AAC) changes color by releasing or absorbing hydrogen ions in response to temperature, changing the pH and enabling it to distinguish temperature. In addition, instead of Poly(NIPAM-co-AAC), a temperature-responsive polymer such as Poly(NIPAM-DMA-AAC) copolymerized with Poly(NIPAM-co-AAC) and dimethylacrylamide (DMA) is used. [Effects of the Invention]

[0006] The present invention enables reversible color change in response to temperature, widens the temperature range that can be visualized, and expands the range of application of warning means for small temperature changes, making it possible to avoid various risks associated with temperature changes. Furthermore, because the gel state gives it viscosity and makes it easy to set, it is less likely to flow, preventing leakage and escape from the containing member, reducing the sealing strength required for containing it, and enabling the inexpensive production of an indicator member that precisely identifies the state when it changes to a specified temperature. The target temperature range can be adjusted depending on the synthesis ratio of the copolymer with the temperature-responsive polymer, further expanding the range of temperature control applications. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a front view of a temperature-sensitive indicating member using the temperature-sensitive material of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the temperature-sensitive indicator shown in FIG. [Figure 3] FIG. 1 is a schematic diagram of equipment used in a method for producing a temperature-sensitive material. [Figure 4] FIG. 2 is a schematic diagram of a container used in the method for producing a temperature-sensitive material. [Figure 5] 10 is a graph showing a comparison of changes in pH with respect to temperature when the mixing ratio of NIPAM and AAC is changed for the temperature-sensitive material according to the first embodiment. [Figure 6] 10 is a table showing a comparison of the pH fluctuation range and the temperature range until a specific pH value is reached when the mixing ratio of NIPAM and AAC is changed for a thermosensitive material. [Figure 7] This is a photograph showing a comparison of the color change with temperature when the mixing ratio of NIPAM and AAC is changed for a thermosensitive material. [Figure 8] 1 is a graph showing a comparison of changes in pH with respect to temperature when the concentration of Poly(NIPAM-co-AAC) is changed for a thermosensitive material. [Figure 9] 10 is a table showing a comparison of the pH fluctuation range and the temperature range until a specific pH value is reached when the concentration of Poly(NIPAM-co-AAC) is changed for a thermosensitive material. [Figure 10]1 is a graph showing a comparison of changes in pH with respect to temperature when the pH adjustment value during polymer synthesis is changed for a thermosensitive material. [Figure 11] 10 is a table showing a comparison of the pH fluctuation range and the temperature range until a specific pH value is reached for thermosensitive materials in which the pH adjustment value during polymer synthesis is changed. [Figure 12] 10 is a graph showing a comparison of changes in pH with respect to temperature when different amounts of glucose are added to a temperature-sensitive material. [Figure 13] 10 is a table showing a comparison of the LCST and pH fluctuation range and the temperature range until a specific pH value is reached when the amount of glucose added to a temperature-sensitive material is changed. [Figure 14] 10 is a photograph showing a comparison of the color change process with respect to temperature between the presence and absence of added glucose in the thermosensitive material. [Figure 15] 10 is a photograph showing the color change process of a temperature-sensitive material using methyl red with respect to temperature. [Figure 16] Photographs showing the color change process of a temperature-sensitive material using methyl red-methylene blue with respect to temperature. [Figure 17] FIG. 10 is a process explanatory diagram of a method for producing a temperature-sensitive material, Poly(NIPAM-DMA-AAC), according to a second embodiment of the present invention. [Figure 18] 1 is a graph showing the change in LCST with respect to the synthesis ratio of DMA in a temperature-sensitive material. [Figure 19] 1 is a graph showing a comparison of changes in pH with respect to temperature when the synthesis ratio of DMA is changed for a thermosensitive material. [Figure 20] 1 is a table showing a comparison of the range of pH fluctuation from LCST to 80° C. when the synthesis ratio of DMA is changed for a thermosensitive material. [Figure 21] 10 is a table showing a comparison of the temperature ranges required to reach pH 5.2 or pH 6.0 when the synthesis ratio of DMA is changed for a thermosensitive material. [Figure 22] 10 is a photograph showing a comparison of the color change process with temperature using methyl red when the composition ratio of DMA is changed for a temperature-sensitive material. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described with reference to the drawings. 1 and 2, a temperature-sensitive display member 1 using a temperature-sensitive material according to the present invention is a thin, plate-like member comprising a pair of parallel, overlapping transparent glass plates 2 with a gap between them; a roughly U-shaped silicone rubber spacer 3 interposed between the glass plates 2 to form a storage space between them; and a temperature-sensitive material 4 injected and stored in the space surrounded by the spacer 3 and the glass plates 2. The temperature-sensitive display member 1 is formed by stacking the spacer 3 between the opposing glass plates 2 and the glass plates 2, with the opening end of the spacer 3 being open to the outside, allowing the temperature-sensitive material 4 to be injected. As shown in FIG. 2, the temperature-sensitive display member 1 is secured between the pair of opposing glass plates 2, sandwiching the spacer 3 between them. The side edges are secured by clamping means (in this embodiment, clips 5 are used for simplicity). To prevent deterioration due to evaporation of moisture from the temperature-sensitive display member, the temperature-sensitive display member is sealed in a storage frame secured with adhesive or a thin film. However, no sealing means, such as the addition of a sealant, is required to ensure high airtightness.

[0009] The temperature-sensitive material 4 is formed into a gel by mixing a polysaccharide, which is a gelling agent, with a solvent containing Poly(NIPAM-co-AAC), and changes color in response to the phase transition by mixing a pH indicator. Poly(NIPAM-co-AAC) is a polymer obtained by copolymerizing N-isopropylacrylamide (NIPAM), a temperature-responsive polymer, with acrylic acid (AAC), an acidic monomer. Poly(NIPAM-co-AAC) swells by hydration, attracting water molecules at temperatures below the LCST of around 35°C, and the carboxyl groups (-COOH) on the AAC side chains convert to hydrogen ions (H + ) and the carboxyl group ionizes (-COO - ), the pH drops, while at the higher temperatures, the water molecules are released and the water shrinks due to dehydration, and hydrogen ions (H +The indicator exhibits a reversible phase transition characteristic in which the pH rises as the carboxyl group (-COOH) is recombined with the carboxyl group (-COOH). The indicator changes color in response to temperature due to the change in pH that accompanies the phase transition of Poly(NIPAM-co-AAC) caused by temperature changes, and the color change or its shade continuously indicates the temperature. The pH indicator can be changed appropriately depending on the display color of the temperature-sensitive material, and well-known indicators such as Congo red solution, methyl red, methyl red-methylene blue solution, and bromothymol blue solution can be used, with the amount added being adjusted appropriately depending on the chemical solution.

[0010] As shown in Figure 3, the equipment for experimentally producing Poly(NIPAM-co-AAC) in the temperature-sensitive material 4 includes a container 6 for containing the solution, a thermostatic bath 7 in which the sealed container 6 is filled with water and immersed to adjust the solution temperature, a temperature controller 8 that detects the solution temperature in the container 6 and controls the thermostatic bath 7 to adjust it to the desired temperature, and a tank 10 that supplies nitrogen at a desired pressure into the container 6 via a flow meter 9. As shown in Figure 4, the container 6 is equipped with an exhaust pipe 12 that connects the inside and outside of the container 6 and is inserted into the container 6 through a sealing lid 11, an air supply pipe 13 that is connected to the tank 10 via the flow meter 9, a thermocouple 14 that is connected to a thermometer to detect the solution temperature, and a stirrer 15 that stirs the solution.

[0011] A method for manufacturing the temperature-sensitive material 4 will be described with reference to FIG. 50 mL of distilled water, a total of 150 to 270 mmol / L of NIPAM and acrylic acid (AAC), and 45 mg of sodium dodecyl sulfate (SDS), a negatively charged surfactant used as a dispersant, are placed in container 6 and mixed. To this mixed solution, an acidic solution such as hydrochloric acid or an alkaline solution such as sodium hydroxide is added to adjust the pH to an acidic range of 2 to 4. When polymerizing NIPAM and AAC, the presence of oxygen causes a side reaction and inhibits the polymerization of Poly(NIPAM-co-AAC). Therefore, nitrogen bubbling treatment is performed for 30 minutes through flow meter 9 and tank 10. In order to prepare a polymer with sufficient molecular weight from NIPAM and the acidic monomer acrylic acid (AAC), 1 mL of ammonium persulfate (APS) as a polymerization initiator at a concentration of 70 mg / mL is added, and then the mixture is stirred for 3 hours under a nitrogen atmosphere while adjusting the solution temperature to 40°C using a thermostatic bath 7 and a temperature controller 8 to carry out the polymerization process. Dialysis is performed for about two days using a dialysis membrane to separate Poly(NIPAM-co-AAC) in container 6 from unreacted molecules and molecules with low molecular weight. Note that the separation time depends on the concentration gradient, so it can be shortened by increasing the number of times the water outside the membrane is exchanged. After dialysis, Poly(NIPAM-co-AAC) is dissolved in water and completely separated from the water. To achieve this, the solution is transferred to another container, frozen, and then subjected to freeze-drying, which involves reducing the pressure inside the container to lower the boiling point of the water molecules and causing the ice to sublimate into water vapor, completely removing the water. This freeze-drying process allows for the extraction of Poly(NIPAM-co-AAC) in powder form. Experiments have confirmed that water removal is possible when a 100 mL solution is frozen and freeze-dried for approximately one and a half to two days using a vacuum pump with an evacuation speed of 65 L / 80 min and a vacuum level of 0.067 Pa. Note that the processing time varies depending on the volume of solution, evacuation speed, and vacuum level.

[0012] A method for producing the temperature-sensitive material 4 using the above-mentioned Poly(NIPAM-co-AAC) will be described. A container is charged with 0.05 g of Poly(NIPAM-co-AAC) per 10 mL of distilled water, the required amount of pH indicator, and 0.1 g of agar powder (gelling agent). The solution is heated to 90°C while stirring to dissolve the agar. The solution is then poured into the space between the spacer 3 and the glass plate 2, and left to stand for 12 hours or more while maintaining an atmosphere at 5°C, causing it to gel and become the temperature-sensitive material 4. It is also possible to combine multiple pH indicators to be added to produce the desired color.

[0013] When the NIPAM:AAC composition ratio of thermosensitive material 4 was varied to examine the change in pH with temperature, as shown in the graph in Figure 5, the LCST remained constant at 35°C regardless of the composition ratio, but differences in pH change became apparent above the LCST. Specifically, as shown in the table in Figure 6, for thermosensitive material 4 with different NIPAM:AAC composition ratios, the pH fluctuation range from 35 to 60°C and the temperature range up to pH 5.2, at which the pH indicator Congo Red turns red, widened as the AAC composition concentration increased. When the NIPAM:AAC composition ratio was varied to examine the color change behavior of thermosensitive material 4, the temperature range at which the color turned red gradually shifted toward higher temperatures as the AAC concentration increased, as shown in Figure 7. These results suggest that the color change temperature range of thermosensitive material 4 can be adjusted by the NIPAM / AAC composition ratio.

[0014] When the concentration of Poly(NIPAM-co-AAC) in the thermosensitive material 4 was varied to examine the change in pH versus temperature, as shown in the graph in Figure 8, the lower the concentration of Poly(NIPAM-co-AAC), the smaller the increase in pH. That is, as shown in the table in Figure 9, when the concentration of Poly(NIPAM-co-AAC) was low, the pH fluctuation range became smaller, but the temperature range over which the pH reached 5.8 expanded. These results indicate that the color-changing temperature range of the thermosensitive material can be adjusted by the concentration of Poly(NIPAM-co-AAC).

[0015] When the initial pH value during polymerization of Poly(NIPAM-co-AAC) was varied for thermosensitive material 4 to examine the change in pH with temperature, the results showed that the lower the initial pH value, the smaller the pH change, as shown in the graph in Figure 10. That is, as shown in Figure 11, the lower the initial pH, the smaller the pH fluctuation range, but the wider the temperature range over which the pH reaches 5.8. These results indicate that the color-changing temperature range of the thermosensitive material can be adjusted by changing the initial pH.

[0016] We investigated the pH change with temperature by varying the amount of glucose, the gelling agent in thermosensitive material 4. As shown in the graph in Figure 12, the pH change was greater with increasing glucose concentration. As shown in the table in Figure 13, the LCST decreased with increasing glucose concentration, and the temperature range required to reach pH 5.2 shifted to a lower temperature. This suggests that the temperature range of thermosensitive materials can be adjusted by adjusting the amount of glucose added. We also investigated the color change behavior of thermosensitive materials with and without glucose, and confirmed that the LCST decreases with the presence or absence of glucose, as shown in Figure 14. The chemical structure of PNIPAM contains hydrophilic portions (amide groups) that easily hold many water molecules. When external thermal energy is applied, the water molecules held in the hydrophilic portions are released, and the hydrophobic isopropyl groups aggregate (become cloudy) through hydrophobic interactions, changing the pH of Poly(NIPAM-co-AAC). However, because the amide groups hold a large number of water molecules, the thermal energy required for release also increases, resulting in a nearly fixed LCST. Therefore, to reduce the amount of water molecules held by PNIPAM, it is effective to add sugars such as glucose, which have many hydroxyl groups that interact strongly with water molecules, as gelling agents. Sugars with the same structure as sucrose or maltose can also be used. Furthermore, we investigated the color change process with temperature changes for thermosensitive materials manufactured using methyl red and methyl red-methylene blue solutions as indicators under conditions of NIPAM:AAC = 95:5 and the addition of 1 g of glucose. As a result, we confirmed that in both cases the color change state gradually changed depending on the temperature, as shown in Figures 15 and 16.

[0017] Another embodiment of the present invention will now be described. The temperature-sensitive material 4 uses Poly(NIPAM-DMA-AAC) instead of Poly(NIPAM-co-AAC) in the previous embodiment, and like the previous embodiment, it is made into a gel by a gelling agent and changes color in response to a phase transition by a pH indicator. Poly(NIPAM-DMA-AAC) is a polymer obtained by copolymerizing NIPAM, a temperature-responsive polymer, AAC, an acidic monomer, and dimethylacrylamide (DMA), which has a higher hydration power than NIPAM. Like the previous embodiment, Poly(NIPAM-DMA-AAC) swells due to hydration in a temperature range below the LCST, and also condenses hydrogen ions (H + ) and ionize, lowering the pH, while in the upper temperature range, dehydration causes contraction by releasing water molecules and hydrogen ions (H + ) is taken in and recombined, resulting in a reversible phase transition in which the pH rises. Furthermore, the thermosensitive material 4 has a stronger ability to retain water molecules due to DMA, which increases the thermal energy required for dehydration, so that the LCST shifts to a higher temperature than 35°C in the previous embodiment depending on the synthesis ratio of DMA.

[0018] A method for producing the temperature-sensitive material 4, Poly(NIPAM-DMA-AAC), using the equipment shown in FIGS. 3 and 4, similar to the previous embodiment, will be described with reference to FIG. To a container 6, 50 mL of distilled water, 234 mmol / L in total of NIPAM, DMA, and AAC, and 45 mg of SDS, a negatively charged surfactant, are added as a dispersant. The pH of this mixed solution is adjusted to an acidic pH of 4.1 using hydrochloric acid or sodium hydroxide solution. As described below, this pH value is allowed to be within a certain range around pH 4.0, as long as it is lower than the pH value at the LCST of Poly(NIPAM-DMA-AAC). In order to prevent the polymerization from being inhibited by a side reaction due to dissolved oxygen when polymerizing NIPAM, DMA, and AAC, nitrogen is bubbled through the flowmeter 9 and tank 10 for 30 minutes. To this mixed solution, 1 mL of APS, a polymerization initiator, is added at a concentration of 70 mg / mL, and after stirring for 1 minute, a polymerization treatment is carried out by stirring for 3 hours under a nitrogen atmosphere while maintaining the solution temperature at 45°C using a thermostatic bath 7 and a temperature controller 8. In order to separate the copolymerized Poly(NIPAM-DMA-AAC) in the vessel 6 from unreacted molecules and molecules with small molecular weights, dialysis using a dialysis membrane is carried out for about two days. To completely separate the post-dialysis Poly(NIPAM-DMA-AAC) dissolved in water, the solution is transferred to another container and frozen. The pressure inside the container is reduced to lower the boiling point of water molecules, causing the ice to sublimate into water vapor, thereby performing freeze-drying to completely remove the water.

[0019] A method for producing the temperature-sensitive material 4 using the above-mentioned Poly(NIPAM-DMA-AAC) will be described. 10 mL of distilled water, 0.05 to 0.1 g of Poly(NIPAM-DMA-AAC), the required amount of pH indicator, and 0.1 to 0.2 g of agar powder (gelling agent) are placed in a container 6, and heated to 90°C while stirring to dissolve the agar. This solution is then poured into the storage space between the spacer 3 and the glass plate 2, and left to stand for 12 hours or more while maintaining an atmosphere at 5°C to gel and produce a temperature-sensitive material 4.

[0020] When we investigated the change in LCST versus the amount of DMA for Poly(NIPAM-DMA-AAC) used in this thermosensitive material 4, we found that the LCST rose with an increase in the amount of DMA (composite ratio of NIPAM to DMA), as shown in the graph in Figure 18. This change occurs because copolymerizing DMA as a monomer with stronger hydration power than the NIPAM monomer strengthens the water molecule retention power of the Poly(NIPAM-DMA-AAC) copolymer, increasing the thermal energy required for dehydration. Monomers that behave similarly to DMA include acrylamide, N-ethylacrylamide, and N-methylacrylamide.

[0021] When the synthetic ratio of NIPAM:DMA in the temperature-sensitive material 4 was changed and the pH fluctuation range from the LCST to 80°C was investigated, the pH fluctuation range became smaller and the LCST shifted to a higher temperature as the amount of DMA increased, as shown in Figures 19 and 20. In other words, as shown in the table in Figure 21, the temperature range shifted to a higher temperature until the pH reached 5.2, the temperature at which the pH indicator Congo Red changed color, or the temperature at which the pH reached 6.0, the temperature at which the pH indicator methyl red changed color. Using methyl red as the indicator for thermosensitive material 4, the NIPAM:DMA composition ratio was changed to investigate the change in color of pH versus temperature. As a result, as shown in Figure 22, the temperature range where the color changes from red to pale orange gradually shifted to the higher temperature side as the amount of DMA increased. From these results, it was confirmed that the color change temperature range can be controlled to the higher temperature side by using Poly(NIPAM-DMA-AAC) copolymer in which DMA is copolymerized as a thermosensitive material. [Explanation of symbols]

[0022] 1 Temperature-sensitive display material 2 glass plates 2a Display section 3 spacers 4. Temperature-sensitive material 5 clips 6 containers 7 Temperature bath 8 Temperature Controller 9 Flow meter 10 Tank 11 Sealing lid 12 exhaust pipe 13 Air pipe 14 Thermocouple 15 Stirrer

Claims

1. A method for producing a thermosensitive material, comprising mixing 0.05 g of Poly(NIPAM-co-AAC), a copolymer of N-isopropylacrylamide (NIPAM) and acrylic acid (AAC), a required amount of an indicator that changes color depending on the pH, and 0.1 g of a gelling agent that maintains the material in a gel state, per 10 mL of distilled water, and then heating to dissolve and then gelling the material.

2. A method for producing the thermosensitive material described in claim 1, characterized in that 45 mg of sodium dodecyl sulfate (SDS) is added to a solution of a mixture of the NIPAM and the AAC at a concentration of 150 to 270 mmol / L per 50 mL of distilled water, the pH is adjusted to 2 to 4 with a pH adjuster, the solution is subjected to a nitrogen bubbling treatment, 1 mL of 70 mg / mL ammonium persulfate (APS) is added, polymerization is performed at 40°C under a nitrogen atmosphere, and the solution is dialyzed and freeze-dried to produce the Poly(NIPAM-co-AAC).

3. A method for detecting a temperature-responsive polymer in a solvent, a gelling agent for maintaining the solvent in a gel state, and an indicator for causing the solvent to change color depending on pH, The temperature is identified by a color change caused by a change in pH due to the temperature of the solvent being released or absorbed by the temperature-responsive polymer, The temperature-responsive polymer is a temperature-sensitive material characterized by being Poly(NIPAM-co-AAC) obtained by copolymerizing N-isopropylacrylamide (NIPAM) and acrylic acid (AAC), and Poly(NIPAM-XXX-AAC) obtained by copolymerizing any one of dimethylacrylamide, acrylamide, N-ethylacrylamide, and N-methylacrylamide.

4. A method for producing a temperature-sensitive material as described in claim 3, characterized in that 0.05 to 0.1 g of Poly(NIPAM-XXX-AAC), a required amount of the indicator, and 0.1 to 0.2 g of the gelling agent are mixed per 10 mL of distilled water, and the mixture is heated to dissolve and then gelled.

5. A method for producing a thermosensitive material as described in claim 4, characterized in that 45 mg of sodium dodecyl sulfate (SDS) is added to a solution of 95-x mol% NIPAM, x mol% dimethylacrylamide (DMA), and 5 mol% AAC mixed in 50 mL of distilled water at a concentration of 234 mmol / L, the solution is adjusted to approximately pH 4 with a pH adjuster, and then subjected to nitrogen bubbling treatment. 1 mL of 70 mg / mL ammonium persulfate (APS) is then added, and polymerization is carried out at 45°C under a nitrogen atmosphere, followed by dialysis and freeze-drying to produce Poly(NIPAM-XXX-AAC).

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