Preparation method of self-healing temperature-sensitive hydrogel for intelligent window

Abstract

The invention belongs to the field of high polymer materials, and discloses a preparation method of a self-healing temperature-sensitive hydrogel P (cationic monomers such as NIPAM-DMAEMA)-P (anionic monomers such as AM-AA) for an intelligent window, which comprises the following steps: taking a prepared stabilizer carboxymethyl cellulose (CMC) aqueous solution, adding NIPAM and cationic monomers (such as dimethylaminoethyl methacrylate DMAEMA), fully and uniformly mixing, adding a crosslinking agent, and uniformly stirring to obtain a gel solution; adding a cross-linking agent, fully stirring until the solution is transparent, heating to 70 DEG C, adding an initiator, starting to react, introducing nitrogen to remove oxygen during the reaction, and stirring to obtain the uniformly dispersed emulsion. Then adding acrylamide (AM) and an anionic monomer (such as acrylic acid AA), uniformly stirring and mixing, adding an initiator, loading into a mold, and carrying out polymerization reaction at 65 DEG C to obtain the temperature-sensitive self-healing hydrogel. According to the invention, the defect that the volume of the traditional hydrogel shrinks and loses water above the phase-change temperature is overcome, the phase-change temperature of the hydrogel can be regulated and controlled, sunlight can be effectively modulated, and the hydrogel can be quickly healed under the condition of damage.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and specifically relates to a self-healing thermosensitive hydrogel for smart windows and a preparation method thereof Background Art The world's annual energy consumption for heating, cooling and ventilation of buildings accounts for about 30%-40% of the world's total energy. Windows have the highest heat transfer coefficient in the building envelope, and the energy flowing in or out accounts for 50% of the building's energy consumption. Therefore, building energy conservation starting from windows can significantly reduce the energy consumption of air conditioning, heating and lighting.

[0002] At present, new smart control glass (smart window) that can dynamically adjust solar heat as the environment changes has become a research hotspot. This kind of glass can automatically adjust the transmittance of sunlight according to changes in external light, temperature or electrical signals. In hot summer, it can effectively reduce the proportion of sunlight entering the room, thereby reducing the cooling load; in cold winter, it can enhance sunlight transmission, help increase the indoor temperature, and play a role in auxiliary heating. In recent years, thermosensitive hydrogel-type thermochromic smart windows have become a hot topic of research due to their excellent dimming rate and low cost. Thermosensitive hydrogels are formed by the swelling of cross-linked polymer networks in water, and they can respond to changes in external temperature. They usually have a high critical phase transition temperature (UCST) or a low critical phase transition temperature (LCST). At a specific temperature, the volume of the hydrogel changes suddenly, affecting its optical properties. For polymers with LCST, when the temperature is lower than the LCST, the polymer exhibits hydrophilicity, the structure expands, and the hydrogel is transparent; when the temperature is higher than the LCST, the structure of the polymer shrinks and collapses, loses hydrophilicity, and the hydrogel becomes opaque.

[0003] Poly (N-isopropylacrylamide) (PNIPAM) is a common thermosensitive hydrogel material with a hydrophilic amide group and a hydrophobic isopropyl group. However, this thermosensitive hydrogel has several problems: ① After the phase transition occurs at high temperature, the volume collapse occurs, the polymer chain shrinks, and a large amount of water is discharged, which poses a risk of liquid leakage; the phase transition response time is long and cannot be widely used. Therefore, it is hoped to obtain a hydrogel polymerized monomer microsphere with a large surface area to volume ratio, and the migration and exchange of water is faster and more uniform. Under the same external environment, the microsphere can quickly reach a dynamic equilibrium of volume, avoiding the volume shrinkage phenomenon of large hydrogels during water loss. The PNIPAM hydrogel microspheres prepared by the traditional emulsion polymerization method optimize the characteristics of the slow phase change rate of the hydrogel-type smart window, but there are still some problems: ① Because the polymer particles are uniformly dispersed in the aqueous phase, the number of tiny particles and phase interfaces in the hydrogel increases, and the light is scattered multiple times when passing through, which reduces the transmittance at low temperatures and weakens its optical regulation effect. ② The polymer changes from a linear network structure to evenly distributed microspheres, and it becomes difficult to control the phase transition temperature of the hydrogel simply by adjusting the monomer concentration. ③ When the hydrogel is physically damaged (such as cutting, stretching, cracks, etc.), it cannot automatically repair itself, and the service life of the material is short, which increases the maintenance cost and the need for frequent replacement. It is not suitable for systems that require long-term stable operation. Therefore, providing a self-healing temperature-sensitive hydrogel is of great significance for current building energy conservation, smart window applications, etc. Summary of the invention

[0004] The purpose of the present invention is to solve the existing problems and first provide a method for preparing a self-healing, temperature-sensitive hydrogel, which specifically comprises the following steps: 1) Prepare carboxymethyl cellulose aqueous solution; 2) Add N-isopropylacrylamide, cationic monomer and acrylamide to the solution in step 1) and mix well; 3) Add the crosslinking agent to 2), stir thoroughly until the solution is transparent, and then heat and stir; 4) Adding an initiator under heating and stirring, stirring and reacting under nitrogen, to obtain a uniformly dispersed emulsion, in which the molecular chain of the thermosensitive polymer particles contains cations; 5) Adding acrylamide and anionic monomers to the emulsion obtained in step 4), stirring and mixing evenly to obtain a mixed solution; 6) Add an initiator to the mixed solution obtained in step 5), put it into a mold, heat it up and polymerize it to obtain a thermosensitive self-healing hydrogel.

[0005] Preferably, the concentration of the prepared carboxymethyl cellulose aqueous solution in step 1) is 0.02-0.36 wt %. The size of the microsphere particles is regulated by changing the concentration of the prepared carboxymethyl cellulose aqueous solution. The size range of the microsphere particles is 0.05-5 μm.

[0006] Preferably, in step 2), the added mass of the N-isopropylacrylamide is 0.5-10wt% of the total mass of the solution in 1); the added mass of the cationic monomer is 5-10wt% of the mass of the N-isopropylacrylamide; and the added mass of the acrylamide monomer is 10-50wt% of the N-isopropylacrylamide.

[0007] In some embodiments, the added mass ratio of the N-isopropylacrylamide, the cationic monomer, and the acrylamide monomer is (N-isopropylacrylamide / cationic monomer / acrylamide=100 / 5~10 / 10~50).

[0008] Preferably, the cationic monomer in step 2) includes dimethylaminoethyl methacrylate (DMAEMA), N,N-diethylaminoethyl acrylate, acryloyloxyethyltrimethylammonium chloride (MATAC), 4-dimethylaminostyrene, 4-vinylpyridine, N,N-dimethylallylamine, N,N-diethylallylamine, diallylmethylamine, triallylamine, 2-(dimethylamino)ethyl acrylate, etc., preferably dimethylaminoethyl methacrylate (DMAEMA), N,N-diethylaminoethyl acrylate, and 2-(dimethylamino)ethyl acrylate.

[0009] Step 3) The cross-linking agent is N,N'-methylenebisacrylamide; preferably, the added mass of the N,N'-methylenebisacrylamide is 0.05-5wt% of the monomer in step 2).

[0010] Step 4) The initiator is ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride.

[0011] Preferably, the reaction time is 30-60 min; and the stirring speed is 320 r / min.

[0012] Preferably, the anionic monomer in step 5) includes acrylic acid, methacrylic acid, crotonic acid, vinyl sulfonic acid, p-styrene sulfonic acid, maleic acid, fumaric acid, 2-acrylamide-2-methylpropane sulfonic acid, etc., preferably acrylic acid, methacrylic acid, 2-acrylamide-2-methylpropane sulfonic acid.

[0013] Step 6) The initiator is ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride The reaction does not add any crosslinking agent, and crosslinking is achieved by utilizing hydrogen bonds formed between acrylamide (AM) and anionic monomers and ionic bonds formed between anionic monomers and cationic monomer microspheres in the emulsion.

[0014] A self-healing thermosensitive hydrogel, a thermosensitive hydrogel P(cationic monomers such as NIPAM-DMAEMA)-P(anionic monomers such as AM-AA) prepared by the method, wherein the self-healing time of the self-healing thermosensitive hydrogel is within 3 minutes, more preferably within 2 minutes, and further preferably within 1.5 minutes.

[0015] The self-healing thermosensitive hydrogel prepared by the method has a self-healing thermosensitive hydrogel particle content in the range of 0.5-10%. The self-healing thermosensitive hydrogel with different thermosensitive polymer contents regulates the visible light after the thermosensitive hydrogel changes color according to the thickness. The thermosensitive polymer with a content of 5.4% corresponds to a hydrogel mold thickness of 1 mm; the thermosensitive polymer with a concentration of 0.45% corresponds to a hydrogel mold thickness of 10 mm; and the thermosensitive polymer with a concentration of 9% corresponds to a hydrogel mold thickness of 0.5 mm.

[0016] Another technical solution of the present invention is to apply the self-healing thermosensitive hydrogel to a smart window.

[0017] Compared with the prior art, the present invention has the following advantages and outstanding effects: 1. Since the method for preparing the thermosensitive hydrogel of the present invention is to first synthesize a thermosensitive polymer microsphere emulsion (containing cations in the molecular chain), and then add acrylamide monomers and anionic monomers to the thermosensitive polymer microsphere emulsion for secondary polymerization, compared with the thermosensitive hydrogel in which the thermosensitive polymer molecular chain is directly located in the cross-linked network structure, the thermosensitive polymer microspheres of the present invention have a particle size of 0.5 to 5 microns, a small particle size, and are uniformly dispersed in the polyacrylamide hydrogel matrix. The migration and exchange of water in the thermosensitive polymer microspheres are faster and more uniform, and the volume is basically unchanged under high and low temperature phase transitions, avoiding the disadvantage of water precipitation and leakage due to volume shrinkage.

[0018] 2. Since the emulsion prepared in the present invention adopts the method of dispersion polymerization, the particle size of the microsphere particles can be effectively controlled to be below 20 microns, and the microsphere particles are evenly distributed in the aqueous phase. This uniform microsphere structure can effectively scatter light when exposed to sunlight, significantly reducing the direct transmission of light. In this way, the modulation effect of the thermosensitive polymer microsphere composite hydrogel on sunlight is significantly improved, and it can effectively adjust the transmission and reflection of light at different temperatures in practical applications, and is particularly suitable for energy-saving building materials or smart window systems that require light regulation.

[0019] 3. Since the thermosensitive hydrogel provided by the present invention is copolymerized with a variety of hydrophilic monomers and N-isopropylacrylamide, the hydrophilicity of the copolymerized monomers and their ratio have an important influence on the phase transition behavior of the hydrogel. By reasonably selecting and controlling the quality of these monomers, the lower critical phase transition temperature (LCST) of the hydrogel can be flexibly adjusted to meet the needs of different environments and application scenarios, making it perform better in the fields of smart windows, sensors or temperature control materials.

[0020] 4. The present invention adopts a two-step method to synthesize thermosensitive hydrogels. In the first step, monomers containing cationic groups, such as dimethylaminoethyl methacrylate (DMAEMA) and N,N-diethylaminoethyl acrylate, are introduced into the synthesized thermosensitive polymer microspheres to make the microspheres rich in amide groups (-CONH2) and cationic groups (such as dimethylamino groups (-N(CH3)2)). In the second step, anionic monomers are introduced into the hydrogel to make the polyacrylamide molecular chain contain anionic groups such as carboxyl groups (-COOH) and sulfonic acid (-SO3H); that is, the prepared thermosensitive latex particles contain cationic polymers such as dimethylamino groups (-N(CH3)2)) and can be regarded as particles with multiple cationic functional groups, and anionic monomers containing carboxyl groups (-COOH) and other anionic polymers are introduced into the hydrogel, so that the hydrogel contains multiple anionic polymers, and the two can realize dynamic ionic bonds, thereby realizing dynamic ionic crosslinking of the hydrogel. Therefore, the cations rich in the thermosensitive polymer microspheres in the final synthesized thermosensitive hydrogel can be used as both a temperature-responsive material and an ionic crosslinker for the hydrogel. At the same time, through dynamic ionic crosslinking and hydrogen bond interactions, the thermosensitive polymer hydrogel can have excellent self-healing properties. Unlike the use of traditional crosslinkers, the thermosensitive hydrogel under this crosslinking method can repair the broken parts through hydrogen bond rearrangement and combination or electrostatic attraction between positively and negatively charged ionic groups when damaged, and has a strong self-healing ability. This self-healing ability greatly extends the service life of the material, reduces the need for frequent repairs or replacements due to material damage, and has significant advantages in systems with long-term stable operation.

[0021] 5. Since a variety of high-efficiency initiators are used in the process of synthesizing the hydrogel of the present invention, the polymerization reaction is promoted to proceed smoothly. The synergistic effect of these initiators makes the reaction faster and the conversion rate of the polymerization reaction significantly improved, thereby shortening the preparation time, reducing the generation of by-products, and improving the purity and quality of the product. The high conversion rate also means that the preparation of the material is more efficient, can achieve large-scale production, and reduce production costs.

[0022] 6. Since the present invention uses a colorless and transparent sodium carboxymethyl cellulose (CMC) solution as a polymerization stabilizer, CMC is a common natural polymer material that is easy to obtain and inexpensive. During the polymerization process, CMC can effectively stabilize the reaction system and prevent excessive aggregation of polymer particles. At the same time, the carboxyl groups contained in the molecular chain can also promote the ionic crosslinking of the hydrogel and improve the mechanical properties of the hydrogel. Since CMC has a wide range of sources and is environmentally friendly, its use not only reduces the production cost of the material, but also makes the preparation process more green and environmentally friendly, meeting the requirements of sustainable development. This further improves the economy and feasibility of the hydrogel of the present invention in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention prepares hydrogel.

[0024] Figure 2 Traditional volume shrinking hydrogel.

[0025] Figure 3 Before hydrogel phase transition.

[0026] Figure 4 After the hydrogel phase transition.

[0027] Figure 5 Phase transition blackbody temperature change diagram.

[0028] Figure 6 The self-healing effect process diagram, where 6-1 is the state before self-healing begins, 6-2 is the self-healing for 60 seconds, and 6-3 is the self-healing for 90 seconds.

[0029] Figure 7 The invention prepares a hydrogel emulsion particle size distribution diagram.

[0030] Figure 8 A schematic diagram of ionic crosslinking formed by an anionic acrylic acid (AA) monomer containing a carboxyl group (-COOH) and a cationic group monomer containing a dimethylamino group (-N(CH3)2) in a thermosensitive hydrogel provided by the present invention. DETAILED DESCRIPTION

[0031] The following embodiments are given in conjunction with the accompanying drawings and the present invention is specifically described. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Technical personnel skilled in the art may make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention, which still fall within the scope of protection of the present invention.

[0032] Example 1 This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0033] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0034] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0035] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0036] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix well.

[0037] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 1.

[0038] Sample 1 in this example is the best sample for testing. Figure 1 The corresponding effect diagram of the volume of the hydrogel of sample 1 remaining unchanged after multiple high-low temperature cycles. The specific operation of high-low temperature cycle: put the hydrogel of sample 1 into a high temperature oven of 70℃ for 10 minutes, then put it into 0℃ ice water for cooling for 10 minutes, and repeat this process 10 times.

[0039] Figure 3 Corresponding to the effect diagram of sample 1 before phase change, it can be seen that at room temperature, the hydrogel corresponding to sample 1 has good transparency; Figure 4 Corresponding to the effect diagram of sample 1 after phase change (temperature is 50°C), it can be seen that after the phase change, the hydrogel corresponding to sample 1 has a good degree of opacity.

[0040] Test experiment operation: make a self-made closed small room of 30cm*30cm*30cm, open a square notch of the same size as the mold of the present invention on the top, place the mold on the notch, irradiate with a xenon lamp at a vertical distance of 20cm from the notch, put a phase change black body in the closed room, align it with the notch on the top, and cover the surroundings with black cardboard to ensure that there is no light reflection. Figure 5Temperature variation diagram of phase change blackbody, in which the phase change blackbody simulates indoor temperature and the xenon lamp simulates sunlight. The curve corresponding to sample 1 in the figure is blue. It can be seen from the figure that as time changes, the temperature of sample 1 is stable within the simulation time and has the ability to maintain room temperature.

[0041] Use stainless steel non-contamination scissors to cut the sample 1 hydrogel in the middle. Figure 6 Corresponding to the self-healing effect diagram of sample 1 after being damaged, Figure 6 (1), (2), and (3) represent the self-healing degree of the sample after 30s, 60s, and 90s, respectively.

[0042] Figure 7 The particle size distribution of the emulsion during the preparation of this sample, where the horizontal axis of the figure represents the particle size. The following Table 1 corresponds to the detailed data of the particle size distribution of this sample. It can be seen that the particle size in the emulsion is in the range of 0.05~10 microns.

[0043] Table 1

[0044] Example 2 This example provides a thermosensitive composite hydrogel (sample 2), the preparation method of which is similar to that of example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0045] (2) Add 24 g of N-isopropylacrylamide (NIPAM) and 7.5 g of acrylamide (AM) and mix thoroughly.

[0046] (3) Add 0.32 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0047] (4) Add 0.16 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0048] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0049] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive hydrogel.

[0050] Example 3 This example provides a self-healing thermosensitive composite hydrogel (Sample 3), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0051] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 0.24 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0052] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0053] (4) Add 0.161 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0054] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0055] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0056] Example 4 This example provides a self-healing thermosensitive composite hydrogel (Sample 4), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0057] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 2.4 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0058] (3) Add 0.34 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0059] (4) Add 0.171 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0060] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0061] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0062] Example 5 This example provides a self-healing thermosensitive composite hydrogel (Sample 5), the preparation method of which is similar to that of Example 1, except that in step (2), dimethylaminoethyl methacrylate is replaced with N,N-diethylaminoethyl acrylate of the same mass, and the preparation method is the same as that of Example 1 except for the following steps: Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of N,N-diethylaminoethyl acrylate, and 7.5 g of acrylamide (AM), and mix thoroughly.

[0063] Example 6 This example provides a self-healing thermosensitive composite hydrogel (Sample 6), the preparation method of which is similar to that of Example 1, except that 1.2 g of ethyl 2-(dimethylamino)acrylate is added in step (2). The preparation method is the same as that of Example 1 except for the following steps: Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of ethyl 2-(dimethylamino)acrylate, and 7.5 g of acrylamide (AM), and mix thoroughly.

[0064] Example 7 This example provides a self-healing thermosensitive composite hydrogel (Sample 7), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0065] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 6 g of acrylamide (AM), and mix thoroughly.

[0066] (3) Add 0.31 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0067] (4) Add 0.158 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0068] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0069] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0070] Example 8 This example provides a self-healing thermosensitive composite hydrogel (Sample 8), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0071] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 4.5 g of acrylamide (AM), and mix thoroughly.

[0072] (3) Add 0.3 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0073] (4) Add 0.15 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0074] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0075] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0076] Example 9 This example provides a self-healing thermosensitive composite hydrogel (Sample 9), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0077] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 3 g of acrylamide (AM) and mix thoroughly.

[0078] (3) Add 0.28 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0079] (4) Add 0.143 g of initiator ammonium persulfate and 0.143 g of 2,2'-azobisisobutylamidine dihydrochloride to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0080] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0081] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0082] Attached Figure 5 Phase change blackbody temperature change diagram, where the phase change blackbody simulates the indoor temperature, the xenon lamp simulates the sunlight, and the curve corresponding to this sample 9 in the figure is red. It can be seen from the figure that as time changes, the temperature of sample 9 remains stable during the simulation time and has the ability to maintain room temperature.

[0083] Example 10 This embodiment provides a self-healing thermosensitive composite hydrogel (sample 10), and its preparation method is similar to that of embodiment 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0084] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 1.5 g of acrylamide (AM), and mix thoroughly.

[0085] (3) Add 0.27 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0086] (4) Add 0.135 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0087] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0088] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0089] Embodiment 11 This embodiment provides a self-healing thermosensitive composite hydrogel (Sample 11), and its preparation method is similar to that of Example 1, specifically comprising the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0090] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0091] (3) Add 0.0016 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0092] (4) Add 0.164 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0093] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0094] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0095] Example 12 This embodiment provides a self-healing thermosensitive composite hydrogel (Sample 12), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0096] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0097] (3) Add 1.65 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0098] (4) Add 0.172 g of initiator ammonium persulfate and 0.172 g of 2,2'-azobisisobutylamidine dihydrochloride to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0099] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0100] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0101] Embodiment 13 This embodiment provides a self-healing thermosensitive composite hydrogel (Sample 13), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0102] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0103] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0104] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0105] (5) Add 10 g of acrylamide (AM) and 0.1 g of acrylic acid monomer to 91 g of the emulsion in step (4), and stir to mix well.

[0106] (6) Add 0.051 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0107] Embodiment 14 This embodiment provides a self-healing thermosensitive composite hydrogel (Sample 14), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0108] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0109] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0110] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0111] (5) Add 10 g of acrylamide (AM) and 2 g of acrylic acid monomer to 108 g of the emulsion in step (4), and stir to mix well.

[0112] (6) Add 0.06 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0113] Embodiment 15 This embodiment provides a self-healing thermosensitive composite hydrogel (Sample 15), and its preparation method is similar to that of Example 1, specifically comprising the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0114] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0115] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0116] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0117] (5) Add 5 g of acrylamide (AM) and 1 g of acrylic acid monomer to 114 g of the emulsion in step (4), and stir to mix well.

[0118] (6) Add 0.03 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0119] Example 16 This embodiment provides a self-healing thermosensitive composite hydrogel (Sample 16), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0120] (2) Add 30 g of N-isopropylacrylamide (NIPAM), 1.5 g of dimethylaminoethyl methacrylate (DMAEMA), and 9.38 g of acrylamide (AM), and mix thoroughly.

[0121] (3) Add 0.41 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0122] (4) Add 0.207 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0123] (5) Add 20 g of acrylamide (AM) and 1 g of acrylic acid monomer to 84 g of the emulsion in step (4), and stir to mix evenly.

[0124] (6) Add 0.105 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, and react for 30 min to obtain a thermosensitive self-healing hydrogel.

[0125] Embodiment 17 This example provides a self-healing thermosensitive composite hydrogel (Sample 17), the preparation method of which is similar to that of Example 1, except that 1 g of methacrylic acid monomer is added in step (5). The preparation method is the same as that of Example 1 except for the following steps: Add 10 g of acrylamide (AM) and 1 g of methacrylic acid monomer into 99 g of the emulsion in step (4), and stir to mix evenly.

[0126] Embodiment 18 This example provides a self-healing thermosensitive composite hydrogel (Sample 18), the preparation method of which is similar to that of Example 1, except that 1 g of maleic acid monomer is added in step (5). The preparation method is the same as that of Example 1 except for the following steps: Add 10 g of acrylamide (AM) and 1 g of maleic acid monomer into 99 g of the emulsion in step (4), and stir to mix evenly.

[0127] Example 19 (No self-healing) This example provides a thermosensitive composite hydrogel (Sample 19), the preparation method of which is similar to that of Example 1, and specifically includes the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0128] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0129] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0130] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0131] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 98.5 g of the emulsion in step (4), and stir to mix evenly.

[0132] (6) Add 0.5 g of cross-linking agent N,N'-methylenebisacrylamide, add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, start the reaction at a high temperature of 65 °C, react for 30 min, and obtain a thermosensitive hydrogel, which is recorded as sample 19.

[0133] Example 20 (Changing the concentration of the thermosensitive polymer) This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.02 wt% carboxymethyl cellulose solution.

[0134] (2) Add 2 g of N-isopropylacrylamide (NIPAM) and 0.2 g of dimethylaminoethyl methacrylate (DMAEMA) and mix well.

[0135] (3) Add 0.042 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0136] (4) Add 0.0212 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0137] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0138] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 10 mm mold and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 20.

[0139] Attached Figure 5Phase change blackbody temperature change diagram, where the phase change blackbody simulates indoor temperature, the xenon lamp simulates sunlight, and the curve corresponding to this sample 20 in the figure is black. It can be seen from the figure that as time changes, the temperature of sample 20 rises significantly at 1200s and loses the ability to maintain room temperature.

[0140] Example 21 (Changing the concentration of the thermosensitive polymer) This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.24 wt% carboxymethyl cellulose solution.

[0141] (2) Add 24 g of N-isopropylacrylamide (NIPAM) and 1.2 g of dimethylaminoethyl methacrylate (DMAEMA) and mix thoroughly.

[0142] (3) Add 0.252 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0143] (4) Add 0.128 g of initiator ammonium persulfate and 0.128 g of 2,2'-azobisisobutylamidine dihydrochloride to start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 min to obtain a uniformly dispersed emulsion.

[0144] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix well.

[0145] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 21.

[0146] Example 22: Changing the concentration of the thermosensitive polymer This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.4 wt% carboxymethyl cellulose solution.

[0147] (2) Add 44 g of N-isopropylacrylamide (NIPAM) and 2.2 g of dimethylaminoethyl methacrylate (DMAEMA) and mix thoroughly.

[0148] (3) Add 0.462 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0149] (4) Add 0.235 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0150] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0151] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 0.5 mm mold and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 22.

[0152] Example 23: Changing the CMC content to control particle size This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.06 wt% carboxymethyl cellulose solution.

[0153] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0154] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0155] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0156] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0157] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 23.

[0158] The particle size of the latex measured at 25°C was about 0.836 μm during the sample preparation process. Embodiment 24 This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.12 wt% carboxymethyl cellulose solution.

[0159] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0160] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0161] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0162] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0163] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 24.

[0164] The particle size of the latex at 25°C was measured to be approximately 0.751 μm during the sample preparation process. Embodiment 25 This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.18 wt% carboxymethyl cellulose solution.

[0165] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0166] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0167] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0168] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0169] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 25.

[0170] The particle size of the emulsion measured during the sample preparation at 25°C was approximately 0.653 μm.

[0171] Embodiment 26 This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.30 wt% carboxymethyl cellulose solution.

[0172] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0173] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0174] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0175] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0176] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 26.

[0177] The particle size of the latex measured at 25°C was about 0.483 μm during the sample preparation process. Embodiment 27 This embodiment provides a self-healing thermosensitive composite hydrogel. This example provides a method for preparing a self-healing thermosensitive composite hydrogel, which is characterized by comprising the following steps: (1) Prepare 400 g of 0.36 wt% carboxymethyl cellulose solution.

[0178] (2) Add 24 g of N-isopropylacrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0179] (3) Add 0.33 g of cross-linking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0180] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, and start the reaction. During the reaction, nitrogen is passed to remove oxygen and stirring is continued. The reaction is continued for 30 minutes to obtain a uniformly dispersed emulsion.

[0181] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to 99 g of the emulsion in step (4), and stir to mix evenly.

[0182] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold, and start the reaction at a high temperature of 65 °C for 30 min to obtain a thermosensitive self-healing hydrogel, which is recorded as sample 27.

[0183] The particle size of the latex at 25°C was measured to be approximately 0.423 μm during the sample preparation process. Example 28 (Direct polymerization without emulsion) This embodiment provides a traditional thermosensitive composite hydrogel (sample 28), the preparation method of which does not use emulsion polymerization, including the following steps: (1) Add 24 g of N-isopropylacrylamide (NIPAM) to 400 g of water and mix thoroughly.

[0184] (2) Add 10 g of acrylamide (AM) and 0.33 g of the cross-linking agent N,N'-methylenebisacrylamide to 99 g of the solution in step (2), and stir to mix well.

[0185] (3) Add 0.17 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride respectively, put into a 1 mm mold and start the reaction at a high temperature of 65°C for 30 min to obtain a traditional thermosensitive self-healing hydrogel.

[0186] Attached Figure 2 This corresponds to the volume shrinkage effect of sample 28 hydrogel after multiple high-low temperature cycles.

[0187] Example 29 (Direct polymerization without using a temperature-sensitive monomer) This embodiment provides a method for preparing a common non-temperature-sensitive hydrogel (sample 29), comprising the following steps: (1) Add 10 g acrylamide (AM) to 99 g water and stir to mix well.

[0188] (2) Add 0.5 g of crosslinking agent N,N'-methylenebisacrylamide, add 0.01 g of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, put into a 1 mm mold, start the reaction at a high temperature of 65°C, react for 30 minutes, and obtain a common hydrogel.

[0189]

Claims

1. A method for preparing a self-healing thermosensitive hydrogel, characterized in that: The specific steps include: 1) Prepare carboxymethyl cellulose aqueous solution; 2) Add N-isopropylacrylamide, cationic monomer, and acrylamide monomer to the solution in step 1) and mix thoroughly; 3) Add the cross-linking agent N,N'-methylenebisacrylamide to 2), stir thoroughly until the solution is transparent, and then heat and stir; 4) Adding an initiator under heating and stirring, stirring and reacting under nitrogen, to obtain a uniformly dispersed emulsion, in which the molecular chain of the thermosensitive polymer particles contains cations; 5) Adding acrylamide and anionic monomers to the emulsion obtained in step 4), stirring and mixing evenly to obtain a mixed solution; 6) Add an initiator to the mixed solution obtained in step 5), put it into a mold, heat it up and polymerize it to obtain a thermosensitive self-healing hydrogel.

2. The preparation method according to claim 1, characterized in that: Step 2) The mass ratio of the N-isopropylacrylamide, the cationic monomer and the acrylamide monomer added is 100:1-10:10-50.

3. The preparation method according to claim 1, characterized in that: The added mass of the N,N'-methylenebisacrylamide in step 3) is 0.05-5.0wt% of the monomer in step 2).

4. The preparation method according to claim 1, characterized in that: In step 2), the cationic monomer includes any one or more combinations of dimethylaminoethyl methacrylate DMAEMA, N,N-diethylaminoethyl acrylate, acryloyloxyethyltrimethylammonium chloride MATAC, 4-dimethylaminostyrene, 4-vinylpyridine, N,N-dimethylallylamine, N,N-diethylallylamine, diallylmethylamine, triallylamine, and 2-(dimethylamino)ethyl acrylate.

5. The preparation method according to claim 1, characterized in that: In step 5), the anionic monomer includes any one or more combinations of acrylic acid, methacrylic acid, crotonic acid, vinyl sulfonic acid, p-styrene sulfonic acid, maleic acid, fumaric acid, and 2-acrylamido-2-methylpropane sulfonic acid.

6. The preparation method according to claim 1, characterized in that: The concentration of the prepared carboxymethyl cellulose aqueous solution is 0.02-0.36 wt %. The particle size of the microsphere particles is regulated by changing the concentration of the prepared carboxymethyl cellulose aqueous solution. The particle size range of the microsphere particles is 0.05-5 μm.

7. The self-healing thermosensitive hydrogel prepared according to the method according to any one of claims 1 to 6, characterized in that: The content of self-healing thermosensitive hydrogel particles ranges from 0.5 to 10%. Self-healing thermosensitive hydrogels with different thermosensitive polymer contents regulate the visible light after the thermosensitive hydrogel changes color according to the thickness.

8. Application of the self-healing thermosensitive hydrogel according to claim 7 in smart windows.

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