A method for preparing a self-healing temperature-sensitive hydrogel for smart windows

Abstract

The application belongs to the field of high polymer materials, and discloses a preparation method of a self-healing temperature-sensitive hydrogel P(NIPAM-DMAEMA cationic monomer)-P(AM-AA anionic monomer) for a smart window; a prepared stabilizer carboxymethyl cellulose (CMC) aqueous solution is taken, NIPAM and a cationic monomer (such as dimethylaminoethyl methacrylate DMAEMA) are added, and the mixture is uniformly mixed; a crosslinking agent is added, the solution is stirred until transparent, and then heated to 70 DEG C; an initiator is added, and the reaction is started; nitrogen is passed to remove oxygen and the solution is stirred; a uniformly dispersed emulsion is obtained; then acrylamide (AM) and an anionic monomer (such as acrylic acid AA) are added, the mixture is uniformly stirred, an initiator is added, and the mixture is poured into a mold; a polymerization reaction is carried out at 65 DEG C; and a temperature-sensitive self-healing hydrogel is obtained. The application overcomes the defect of volume shrinkage and water loss of a traditional hydrogel above a phase transition temperature, can realize the regulation of the phase transition temperature of the hydrogel and the effective modulation of sunlight, and can quickly heal in a damaged condition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and particularly relates to a self-healing temperature-sensitive hydrogel for smart windows and a preparation method thereof BACKGROUND

[0002] The energy consumption for providing heating, cooling and ventilation for buildings accounts for about 30%-40% of the total global energy consumption every year, and the window is the part with the highest heat transfer coefficient in the building envelope, and the energy inflow or loss accounts for 50% of the building energy consumption. Therefore, starting from the window for building energy saving can significantly reduce the energy consumption of air conditioning, heating and lighting.

[0003] At present, with the change of environment, a new type of intelligent control glass (smart window) capable of dynamically adjusting solar heat has become a research hotspot. This glass can automatically adjust the transmittance of sunlight according to the changes of external light, temperature or electrical signals and other factors. In hot summer, it can effectively reduce the proportion of sunlight entering the room, thereby reducing the cooling load; while in cold winter, it can enhance the sunlight transmission to help improve the indoor temperature, playing the role of auxiliary heating. In recent years, the temperature-sensitive hydrogel type thermochromic smart window has become a research hotspot due to its excellent light modulation rate and low cost. The temperature-sensitive hydrogel is formed by the swelling of a cross-linked polymer network in water, which can respond to the changes of external temperature. It usually has a high critical phase transition temperature (UCST) or a low critical phase transition temperature (LCST). At a certain temperature, the volume of the hydrogel will suddenly change, thereby affecting its optical properties. For the polymer with LCST, when the temperature is lower than LCST, the polymer shows hydrophilicity, the structure expands, and the hydrogel presents a transparent state; when the temperature is higher than LCST, the structure of the polymer shrinks and collapses, loses hydrophilicity, and the hydrogel becomes opaque.

[0004] Poly(N-isopropylacrylamide) (PNIPAM) is a common thermosensitive hydrogel material, possessing hydrophilic amide groups and hydrophobic isopropyl groups. However, this thermosensitive hydrogel has several problems: ① After a phase transition at high temperatures, volume collapse occurs, polymer chains shrink, and a large amount of water is expelled, posing a risk of liquid leakage; the phase transition response time is long, limiting its widespread application. Therefore, it is desirable to obtain hydrogel polymer monomer microspheres with a large surface area to volume ratio, allowing for faster and more uniform water migration and exchange. Under the same external environment, the microspheres can quickly reach dynamic volume equilibrium, avoiding the volume shrinkage phenomenon that occurs in bulk hydrogels during water loss. PNIPAM hydrogel microspheres prepared by traditional emulsion polymerization optimize the slow phase transition rate characteristic of hydrogel-type smart windows, but some problems still exist: ① Because the polymer particles are uniformly dispersed in the aqueous phase, the number of tiny particles and phase interfaces within the hydrogel increases, causing multiple scattering of light as it passes through, reducing the transmittance at low temperatures and weakening its optical modulation effect. ② As the polymer transforms from a linear network structure into uniformly distributed microspheres, controlling the hydrogel phase transition temperature solely by adjusting the monomer concentration becomes difficult. ③ Hydrogels cannot automatically repair themselves when subjected to physical damage (such as cutting, stretching, or cracking), resulting in a short material lifespan, increased maintenance costs, and the need for frequent replacements, making them unsuitable for systems requiring long-term stable operation. Therefore, providing a self-healing temperature-sensitive hydrogel is of great significance for current applications in building energy conservation and smart windows. Summary of the Invention

[0005] The purpose of this invention is to address existing problems by providing a method for preparing a self-healing, temperature-sensitive hydrogel, specifically including the following steps:

[0006] 1) Prepare an aqueous solution of carboxymethyl cellulose;

[0007] 2) Add N-isopropylacrylamide, a cationic monomer, and acrylamide to the solution in step 1), and mix thoroughly.

[0008] 3) Add the cross-linking agent to 2), stir thoroughly until the solution becomes clear, then heat and stir.

[0009] 4) Add the initiator while heating and stirring, and stir the reaction under nitrogen to obtain a uniformly dispersed emulsion, in which the thermosensitive polymer particles contain cations in their molecular chains;

[0010] 5) Add acrylamide and anionic monomer to the emulsion obtained in step 4), stir and mix evenly to obtain a mixture;

[0011] 6) Add an initiator to the mixture obtained in step 5), put it into a mold, heat it to polymerize, and obtain a thermosensitive self-healing hydrogel.

[0012] Preferably, the concentration of the prepared carboxymethyl cellulose aqueous solution in step 1) is 0.02-0.36 wt%, and the particle size of the microspheres is controlled by changing the concentration of the prepared carboxymethyl cellulose aqueous solution, and the particle size of the microspheres is 0.05-5 μm.

[0013] Preferably, the addition amount of the N-isopropyl acrylamide in step 2) is 0.5-10 wt% of the total mass of the solution in step 1); the addition amount of the cationic monomer is 5-10 wt% of the mass of the N-isopropyl acrylamide; and the addition amount of the acrylamide monomer is 10-50 wt% of the mass of the N-isopropyl acrylamide.

[0014] In some embodiments, the addition amount of the N-isopropyl acrylamide, the cationic monomer, and the acrylamide monomer is in a ratio of (N-isopropyl acrylamide / cationic monomer / acrylamide = 100 / 5-10 / 10-50).

[0015] Preferably, the cationic monomer in step 2) includes dimethylaminoethyl methacrylate (DMAEMA), N,N-diethylaminoethyl acrylate, methacryloyloxyethyl trimethylammonium 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.

[0016] The crosslinking agent in step 3) is N,N'-methylenebisacrylamide; preferably, the addition amount of the N,N'-methylenebisacrylamide is 0.05-5 wt% of the monomers in step 2).

[0017] The initiator in step 4) is ammonium persulfate and 2,2'-azobis(2-methylpropionamide) dihydrochloride.

[0018] Preferably, the reaction time is 30-60 min, and the stirring speed is 320 r / min.

[0019] Preferably, the anionic monomer in step 5) includes acrylic acid, methacrylic acid, crotonic acid, vinylsulfonic acid, p-styrenesulfonic acid, maleic acid, fumaric acid, and 2-acrylamido-2-methylpropanesulfonic acid, preferably acrylic acid, methacrylic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0020] The initiator in step 6) is ammonium persulfate and 2,2'-azobis(2-methylpropionamide) dihydrochloride.

[0021] The reaction does not add any crosslinking agent, and the crosslinking is completed by hydrogen bonds formed between acrylamide (AM) and anionic monomers and ionic bonds formed between the anionic monomers and cationic monomer microspheres in the emulsion.

[0022] A self-healing temperature-sensitive hydrogel is prepared by the method, and the self-healing temperature-sensitive hydrogel P(NIPAM-DMAEMA and other cationic monomers)-P(AM-AA and other anionic monomers) has a self-healing time of less than 3 min, preferably less than 2 min, and more preferably less than 1.5 min.

[0023] The self-healing temperature-sensitive hydrogel prepared by the method has a particle content of the self-healing temperature-sensitive hydrogel in the range of 0.5-10%, and the self-healing temperature-sensitive hydrogel with different contents of temperature-sensitive polymers can be adjusted according to the thickness to regulate the visible light after the temperature-sensitive hydrogel changes color, the temperature-sensitive polymer has a content of 5.4%, and the hydrogel mold has a thickness of 1 mm; the temperature-sensitive polymer has a concentration of 0.45%, and the hydrogel mold has a thickness of 10 mm; the temperature-sensitive polymer has a concentration of 9%, and the hydrogel mold has a thickness of 0.5 mm.

[0024] Another technical scheme of the present application is the application of the self-healing temperature-sensitive hydrogel to an intelligent window.

[0025] Compared with the prior art, the present application has the following advantages and outstanding effects:

[0026] 1. The method for preparing the temperature-sensitive hydrogel in the present application is to first synthesize a temperature-sensitive polymer microsphere emulsion (containing cations in the molecular chain), and then to form the temperature-sensitive hydrogel by adding acrylamide monomers and anionic monomers for secondary polymerization, compared with the temperature-sensitive hydrogel in which the temperature-sensitive polymer molecular chain is directly located in the crosslinked network structure, in the present application, the temperature-sensitive polymer microspheres have a particle size of 0.5-5 microns, the particle size is small, and the temperature-sensitive polymer microspheres are uniformly dispersed in the polyacrylamide hydrogel matrix, the migration and exchange of water in the temperature-sensitive polymer microspheres are faster and more uniform, the volume basically does not change under high and low temperature phase transition, and the problem of water leakage caused by volume shrinkage is avoided.

[0027] 2. The emulsion prepared in the present application adopts the dispersion polymerization method, so that the particle size of the microspheres can be effectively controlled to be below 20 microns, and the microspheres are uniformly distributed in the water phase, the uniform microsphere structure can effectively scatter light when the sun is irradiated, and the direct transmission of light is significantly reduced. In this way, the light modulation effect of the temperature-sensitive polymer microsphere composite hydrogel is significantly improved, and the effective adjustment of light transmission and reflection at different temperatures can be realized in actual application, and the temperature-sensitive polymer microsphere composite hydrogel is particularly suitable for energy-saving building materials or intelligent window systems that require light modulation.

[0028] 3. The temperature-sensitive hydrogel provided by the present application uses a variety of hydrophilic monomers to copolymerize with N-isopropyl acrylamide, and the hydrophilicity and proportion of the comonomers have an important influence on the phase transition behavior of the hydrogel. By reasonably selecting and controlling the mass of these monomers, the low critical solution temperature (LCST) of the hydrogel can be flexibly adjusted to meet the needs of different environments and application scenarios, making it perform more superiorly in the fields of smart windows, sensors or temperature control materials, etc.

[0029] 4. The two-step method used in the present application to synthesize temperature-sensitive hydrogel first synthesizes temperature-sensitive polymer microspheres, and then introduces monomers containing cationic groups, such as dimethylaminoethyl methacrylate (DMAEMA) and N,N-diethylaminoethyl acrylate, to make the microspheres rich in amide groups (–CONH2) and cationic groups (such as dimethylamino groups (–N(CH3)2)); In the second step of synthesizing the hydrogel, anionic monomers are introduced to make the polyacrylamide molecular chain contain carboxyl groups (–COOH), sulfonic acid groups (–SO3H) and other anionic groups; That is, the temperature-sensitive latex particles prepared contain dimethylamino groups (–N(CH3)2) and other cationic polymers, which can be regarded as particles with multiple cationic functional groups, and the hydrogel contains multiple anionic polymers by introducing anionic monomers containing carboxyl groups (–COOH), etc. Dynamic ionic bonds can be achieved between the two, thereby realizing the dynamic ionic crosslinking of the hydrogel. Therefore, the cations rich in the temperature-sensitive polymer microspheres in the finally synthesized temperature-sensitive hydrogel can be used as temperature-responsive materials and as ionic crosslinking agents for the hydrogel. At the same time, through dynamic ionic crosslinking and hydrogen bond interaction, the temperature-sensitive polymer hydrogel can have excellent self-healing properties. Unlike the use of traditional crosslinking agents, the temperature-sensitive hydrogel under this kind of crosslinking mode can repair the broken parts through hydrogen bond rearrangement and combination or electrostatic attraction between ion groups with positive and negative charges when damaged, and has strong self-healing ability. This self-healing ability greatly prolongs the service life of the material, reduces the need for frequent maintenance or replacement due to material damage, and has significant advantages in long-term stable operation systems.

[0030] 5. The use of a variety of high-efficiency initiators in the synthesis of the hydrogel of the present application promotes the smooth progress of the polymerization reaction. The synergistic effect of these initiators makes the reaction faster, and the conversion rate of the polymerization reaction is significantly improved, thereby shortening the preparation time, reducing the generation of by-products, and improving the purity and quality of the product. High conversion rate also means that the material is more efficient to prepare, can realize large-scale production, and reduces production costs.

[0031] 6. Since the present application uses colorless and transparent sodium carboxymethyl cellulose (CMC) solution as a polymer stabilizer, CMC is a common natural polymer material, easy to obtain and low in price. During polymerization, CMC can effectively stabilize the reaction system and prevent the polymer particles from excessive aggregation, and the carboxyl contained in the molecular chain can also promote the ionic crosslinking of the hydrogel and improve the mechanical properties of the hydrogel. Because CMC is widely available and 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 enhances the economic and feasibility of the present application in practical applications. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The present application prepares a hydrogel.

[0033] Figure 2 Traditional volume shrinkage hydrogel.

[0034] Figure 3 Before the phase change of the hydrogel.

[0035] Figure 4 After the phase change of the hydrogel.

[0036] Figure 5 Phase change blackbody temperature change diagram.

[0037] Figure 6 Process diagram of self-healing effect, wherein 6-1 is the state of not starting self-healing, 6-2 is the state of self-healing for 60s, and 6-3 is the state of self-healing for 90s.

[0038] Figure 7 The present application prepares a hydrogel emulsion particle size distribution diagram.

[0039] Figure 8 The present application provides a schematic diagram of an anionic acrylic acid (AA) monomer containing a carboxyl group (-COOH) and a cationic monomer containing a dimethylamino group (-N(CH3)2) forming an ionic bond crosslinked hydrogel. DETAILED DESCRIPTION

[0040] The following examples are given in conjunction with the accompanying drawings and a more detailed description of the application, it is necessary to point out that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content of the present application, which still belong to the protection scope of the present application.

[0041] Example 1

[0042] This embodiment provides a self-healing temperature-sensitive composite hydrogel, and this embodiment also provides a method for preparing the self-healing temperature-sensitive composite hydrogel, characterized by the following steps:

[0043] (1) Prepare 400g of 0.24wt% carboxymethyl cellulose solution.

[0044] (2) Add 24g N-isopropylacrylamide (NIPAM), 1.2g dimethylaminoethyl methacrylate (DMAEMA), and 7.5g acrylamide (AM), and mix thoroughly.

[0045] (3) Add 0.33g of crosslinking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70℃.

[0046] (4) Add 0.165 g each of ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride to start the reaction. During the reaction, nitrogen is purged to remove oxygen and the mixture is stirred continuously. After 30 min, a uniformly dispersed emulsion is obtained.

[0047] (5) Add 10g of acrylamide (AM) and 1g of acrylic monomer to the 99g emulsion in step (4) and stir to mix evenly.

[0048] (6) Add 0.055 g each of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, place them in a 1 mm mold, and start the reaction in a high temperature environment of 65°C. After 30 min of reaction, a temperature-sensitive self-healing hydrogel is obtained, which is recorded as sample 1.

[0049] Sample 1 in this example is the optimal sample for testing. Figure 1 The image shows the effect of the hydrogel of sample 1 maintaining its volume after multiple high-low temperature cycles. The specific procedure for high-low temperature cycling is as follows: place the hydrogel of sample 1 in a 70°C oven for 10 minutes, then cool it in 0°C ice water for 10 minutes, repeating this process 10 times.

[0050] Figure 3 The image corresponding to sample 1 before the phase transition shows that the hydrogel of sample 1 has good transparency at room temperature. Figure 4 The image corresponding to sample 1 after the phase transition (at a temperature of 50°C) shows that the hydrogel of sample 1 has good opacity after the phase transition.

[0051] Test procedure: Create a closed small room of 30cm*30cm*30cm, and make a square notch at the top with the same size as the mold described in this invention. Place the mold at the notch and irradiate it with a xenon lamp at a vertical distance of 20cm from the notch. Place a phase change black body in the closed room, align it with the top notch, and cover the sides with black cardboard to ensure no light reflection. Figure 5Phase transition black body temperature change chart, where the phase transition black body simulates indoor temperature, xenon lamp simulates sunlight, the curve corresponding to sample 1 in the chart is blue, and it can be seen from the chart that the temperature of sample 1 is stable over time and has the ability to maintain room temperature.

[0052] The sample 1 hydrogel is cut in half in the middle with a stainless steel non-polluting scissors, Figure 6 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.

[0053] Figure 7 The particle size distribution of the emulsion during the preparation of this sample, where the abscissa of the chart 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 interval of 0.05-10 microns.

[0054] Table 1

[0055]

[0056] Example 2

[0057] This example provides a temperature-sensitive composite hydrogel (sample 2), which is prepared by a method similar to that of Example 1, specifically including the following steps:

[0058] (1) Prepare a 0.24wt% carboxymethyl cellulose solution of 400g.

[0059] (2) Add 24g of N-isopropyl acrylamide (NIPAM) and 7.5g of acrylamide (AM) and mix thoroughly.

[0060] (3) Add 0.32g of crosslinking agent N,N'-methylene bisacrylamide, and after the solution is transparent, heat to 70℃.

[0061] (4) Add 0.16g of initiator ammonium persulfate and 2,2'-azobisdimethylamino dihydrochloride, start the reaction, and during the reaction, continuously stir and remove oxygen by passing nitrogen, and react for 30min to obtain a uniformly dispersed emulsion.

[0062] (5) Add 10g of acrylamide (AM) and 1g of acrylic acid monomer to the 99g emulsion of step (4) and mix thoroughly.

[0063] (6) Add 0.055g of initiator ammonium persulfate and 2,2'-azobisdimethylamino dihydrochloride, and place it in a 1mm mold, start the reaction in a high temperature 65℃ environment, and react for 30min to obtain a temperature-sensitive hydrogel.

[0064] Example 3

[0065] This embodiment provides a self-healing temperature-sensitive composite hydrogel (sample 3), which is prepared by a method similar to that of Example 1, specifically comprising the following steps:

[0066] (1) Prepare a 0.24wt% carboxymethyl cellulose solution of 400g.

[0067] (2) Add 24g of N-isopropyl acrylamide (NIPAM), 0.24g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5g of acrylamide (AM), and mix thoroughly.

[0068] (3) Add 0.33g of crosslinking agent N,N'-methylene bisacrylamide, and stir thoroughly until the solution is transparent, then heat to 70°C.

[0069] (4) Add 0.161g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, start the reaction, and continuously stir and deoxygenate with nitrogen during the reaction, and react for 30min to obtain a uniformly dispersed emulsion.

[0070] (5) Add 10g of acrylamide (AM) and 1g of acrylic acid monomer to the 99g emulsion of step (4), and mix thoroughly.

[0071] (6) Add 0.055g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, and place in a 1mm mold, start the reaction in a high temperature 65°C environment, and react for 30min to obtain a temperature-sensitive self-healing hydrogel.

[0072] Example 4

[0073] This embodiment provides a self-healing temperature-sensitive composite hydrogel (sample 4), which is prepared by a method similar to that of Example 1, specifically comprising the following steps:

[0074] (1) Prepare a 0.24wt% carboxymethyl cellulose solution of 400g.

[0075] (2) Add 24g of N-isopropyl acrylamide (NIPAM), 2.4g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5g of acrylamide (AM), and mix thoroughly.

[0076] (3) Add 0.34g of crosslinking agent N,N'-methylene bisacrylamide, and stir thoroughly until the solution is transparent, then heat to 70°C.

[0077] (4) Add 0.171g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, start the reaction, and continuously stir and deoxygenate with nitrogen during the reaction, and react for 30min to obtain a uniformly dispersed emulsion.

[0078] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 99 g emulsion from step (4) and mix well.

[0079] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride, and place in a 1 mm mold. Start the reaction at a high temperature of 65°C and react for 30 min to obtain a warm-sensitive self-healing hydrogel.

[0080] Example 5

[0081] This example provides a self-healing warm-sensitive composite hydrogel (sample 5), which is prepared by a method similar to that of Example 1, except that in step (2), dimethylaminoethyl methacrylate is replaced by the same mass of N,N-diethylaminoethyl acrylate, and the following steps are consistent with Example 1:

[0082] Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of N,N-diethylaminoethyl acrylate, and 7.5 g of acrylamide (AM), and mix well.

[0083] Example 6

[0084] This example provides a self-healing warm-sensitive composite hydrogel (sample 6), which is prepared by a method similar to that of Example 1, except that in step (2), 1.2 g of 2-(dimethylamino)ethyl acrylate is added, and the following steps are consistent with Example 1:

[0085] Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of 2-(dimethylamino)ethyl acrylate, and 7.5 g of acrylamide (AM), and mix well.

[0086] Example 7

[0087] This example provides a self-healing warm-sensitive composite hydrogel (sample 7), which is prepared by a method similar to that of Example 1, and specifically includes the following steps:

[0088] (1) Prepare a 0.24 wt% carboxymethyl cellulose solution of 400 g.

[0089] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 6 g of acrylamide (AM), and mix well.

[0090] (3) Add 0.31 g of crosslinking agent N,N'-methylenebisacrylamide, and mix well until the solution is transparent. Then heat to 70°C.

[0091] (4) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.158 g, start reaction, nitrogen is passed during the reaction to remove oxygen and do not stop stirring, reaction for 30 min, get uniform dispersion emulsion.

[0092] (5) Add 10 g of acrylamide (AM), 1 g of acrylic acid monomer to the 99 g emulsion of step (4), stir and mix evenly.

[0093] (6) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.055 g, put into 1 mm mold, start reaction in high temperature 65 ℃ environment, reaction for 30 min, get temperature-sensitive self-healing hydrogel.

[0094] Example 8

[0095] This example provides a self-healing temperature-sensitive composite hydrogel (sample 8), the preparation method is similar to example 1, which specifically includes the following steps:

[0096] (1) Prepare 0.24wt% carboxymethyl cellulose solution 400 g.

[0097] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), 4.5 g of acrylamide (AM), and mix thoroughly.

[0098] (3) Add 0.3 g of crosslinking agent N,N'-methylene bisacrylamide, stir thoroughly, then heat to 70 ℃.

[0099] (4) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.15 g, start reaction, nitrogen is passed during the reaction to remove oxygen and do not stop stirring, reaction for 30 min, get uniform dispersion emulsion.

[0100] (5) Add 10 g of acrylamide (AM), 1 g of acrylic acid monomer to the 99 g emulsion of step (4), stir and mix evenly.

[0101] (6) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.055 g, put into 1 mm mold, start reaction in high temperature 65 ℃ environment, reaction for 30 min, get temperature-sensitive self-healing hydrogel.

[0102] Example 9

[0103] This example provides a self-healing temperature-sensitive composite hydrogel (sample 9), the preparation method is similar to example 1, which specifically includes the following steps:

[0104] (1) Prepare 0.24wt% carboxymethyl cellulose solution 400 g.

[0105] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), 3 g of acrylamide (AM), and mix well.

[0106] (3) Add 0.28 g of crosslinking agent N,N'-methylene bisacrylamide, and stir well until the solution is transparent. Then heat to 70°C.

[0107] (4) Add 0.143 g of initiator ammonium persulfate and 2,2'-azobisdimethylamino dihydrochloride, start the reaction, and continuously stir while purging nitrogen to remove oxygen. React for 30 min to obtain a uniformly dispersed emulsion.

[0108] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 99 g emulsion of step (4), and mix well.

[0109] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylamino dihydrochloride, and place in a 1 mm mold. Start the reaction at a high temperature of 65°C, and react for 30 min to obtain a temperature-sensitive self-healing hydrogel.

[0110] Figure 9 Figure 5 Phase change blackbody temperature change diagram, where the phase change blackbody simulates indoor temperature and the xenon lamp simulates sunlight. The curve corresponding to sample 9 in the figure is red. As can be seen from the figure, the temperature of sample 9 remains stable over time within the simulated time, indicating its ability to maintain room temperature.

[0111] Example 10

[0112] This example provides a self-healing temperature-sensitive composite hydrogel (sample 10), which is prepared by a method similar to that of example 1, specifically comprising the following steps:

[0113] (1) Prepare a 0.24 wt% carboxymethyl cellulose solution of 400 g.

[0114] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 1.5 g of acrylamide (AM), and mix well.

[0115] (3) Add 0.27 g of crosslinking agent N,N'-methylene bisacrylamide, and stir well until the solution is transparent. Then heat to 70°C.

[0116] (4) Add 0.135 g of initiator ammonium persulfate and 2,2'-azobisdimethylamino dihydrochloride, start the reaction, and continuously stir while purging nitrogen to remove oxygen. React for 30 min to obtain a uniformly dispersed emulsion.

[0117] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 99 g emulsion of step (4) and mix well.

[0118] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, respectively, into a 1 mm mold, start the reaction in a high temperature 65°C environment, and react for 30 min to obtain a temperature-sensitive self-healing hydrogel.

[0119] Example 11

[0120] This example provides a self-healing temperature-sensitive composite hydrogel (sample 11), and the preparation method is similar to that of example 1, which specifically includes the following steps:

[0121] (1) Prepare a 0.24wt% carboxymethyl cellulose solution of 400 g.

[0122] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix well.

[0123] (3) Add 0.0016 g of crosslinking agent N,N'-methylene bisacrylamide, and after the solution is transparent, heat to 70°C.

[0124] (4) Add 0.164 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, respectively, start the reaction, and during the reaction, continuously stir and remove oxygen by nitrogen, and react for 30 min to obtain a uniformly dispersed emulsion.

[0125] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 99 g emulsion of step (4) and mix well.

[0126] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, respectively, into a 1 mm mold, start the reaction in a high temperature 65°C environment, and react for 30 min to obtain a temperature-sensitive self-healing hydrogel.

[0127] Example 12

[0128] This example provides a self-healing temperature-sensitive composite hydrogel (sample 12), and the preparation method is similar to that of example 1, which specifically includes the following steps:

[0129] (1) Prepare a 0.24wt% carboxymethyl cellulose solution of 400 g.

[0130] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), 7.5 g of acrylamide (AM), and mix well.

[0131] (3) Add 1.65 g of crosslinking agent N,N'-methylenebisacrylamide, and stir well until the solution is transparent. Then heat to 70°C.

[0132] (4) Add 0.172 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, start the reaction, and continuously stir while purging nitrogen to remove oxygen. The reaction is carried out for 30 min to obtain a uniformly dispersed emulsion.

[0133] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 99 g emulsion of step (4), and mix well.

[0134] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, and place in a 1 mm mold. Start the reaction at a high temperature of 65°C, and the reaction is carried out for 30 min to obtain a temperature-sensitive self-healing hydrogel.

[0135] Example 13

[0136] This example provides a self-healing temperature-sensitive composite hydrogel (sample 13), which is prepared by a method similar to that of example 1, and specifically includes the following steps:

[0137] (1) Prepare a 0.24 wt% carboxymethyl cellulose solution of 400 g.

[0138] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix well.

[0139] (3) Add 0.33 g of crosslinking agent N,N'-methylenebisacrylamide, and stir well until the solution is transparent. Then heat to 70°C.

[0140] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, start the reaction, and continuously stir while purging nitrogen to remove oxygen. The reaction is carried out for 30 min to obtain a uniformly dispersed emulsion.

[0141] (5) Add 10 g of acrylamide (AM) and 0.1 g of acrylic acid monomer to the 91 g emulsion of step (4), and mix well.

[0142] (6) Add initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride 0.051 g each, put into 1 mm mold, start reaction in high temperature 65℃ environment, reaction for 30 min, get temperature-sensitive self-healing hydrogel.

[0143] Example 14

[0144] This example provides a self-healing temperature-sensitive composite hydrogel (sample 14), its preparation method is similar to example 1, specifically including the following steps:

[0145] (1) Prepare 0.24wt% carboxymethyl cellulose solution 400g.

[0146] (2) Add 24g N-isopropyl acrylamide (NIPAM), 1.2g of dimethylaminoethyl methacrylate (DMAEMA), 7.5g of acrylamide (AM), mix well.

[0147] (3) Add 0.33g crosslinking agent N,N'-methylene bisacrylamide, fully stir until the solution is transparent, then heat to 70℃.

[0148] (4) Add initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride 0.165 g each, start reaction, nitrogen is passed during the reaction to remove oxygen and stirring is not stopped, reaction for 30 min, get uniform dispersion emulsion.

[0149] (5) Add 10g acrylamide (AM), 2g acrylic acid monomer to 108g emulsion in step (4), mix well.

[0150] (6) Add initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride 0.06 g each, put into 1 mm mold, start reaction in high temperature 65℃ environment, reaction for 30 min, get temperature-sensitive self-healing hydrogel.

[0151] Example 15

[0152] This example provides a self-healing temperature-sensitive composite hydrogel (sample 15), its preparation method is similar to example 1, specifically including the following steps:

[0153] (1) Prepare 0.24wt% carboxymethyl cellulose solution 400g.

[0154] (2) Add 24g N-isopropyl acrylamide (NIPAM), 1.2g of dimethylaminoethyl methacrylate (DMAEMA), 7.5g of acrylamide (AM), mix well.

[0155] (3) Add 0.33g crosslinking agent N,N'-methylene bisacrylamide, fully stir until the solution is transparent, then heat to 70℃.

[0156] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride, respectively, start the reaction, and continuously stir and deoxygenate with nitrogen during the reaction. After 30 min, a uniformly dispersed emulsion is obtained.

[0157] (5) Add 5 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 114 g emulsion obtained in step (4) and mix well.

[0158] (6) Add 0.03 g of initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride, respectively, and place in a 1 mm mold. Start the reaction at a high temperature of 65°C, and after 30 min, a temperature-sensitive self-healing hydrogel is obtained.

[0159] Example 16

[0160] This example provides a self-healing temperature-sensitive composite hydrogel (sample 16), which is prepared by a method similar to that of Example 1 and specifically includes the following steps:

[0161] (1) Prepare a 0.24 wt% carboxymethyl cellulose solution of 400 g.

[0162] (2) Add 30 g of N-isopropyl acrylamide (NIPAM), 1.5 g of dimethylaminoethyl methacrylate (DMAEMA), and 9.38 g of acrylamide (AM), and mix well.

[0163] (3) Add 0.41 g of crosslinking agent N,N'-methylenebisacrylamide, and after the solution is well stirred and transparent, heat to 70°C.

[0164] (4) Add 0.207 g of initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride, respectively, start the reaction, and continuously stir and deoxygenate with nitrogen during the reaction. After 30 min, a uniformly dispersed emulsion is obtained.

[0165] (5) Add 20 g of acrylamide (AM) and 1 g of acrylic acid monomer to the 84 g emulsion obtained in step (4) and mix well.

[0166] (6) Add 0.105 g of initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride, respectively, and place in a 1 mm mold. Start the reaction at a high temperature of 65°C, and after 30 min, a temperature-sensitive self-healing hydrogel is obtained.

[0167] Example 17

[0168] This example provides a self-healing temperature-sensitive composite hydrogel (sample 17), which is prepared by a method similar to that of Example 1, except that 1 g of methacrylic acid monomer is added in step (5).

[0169] Add 10 g of acrylamide (AM) and 1 g of methacrylic acid monomer into the 99 g emulsion of step (4) and mix well.

[0170] Example 18

[0171] This example provides a self-healing temperature-sensitive composite hydrogel (sample 18) which is prepared in a similar manner to example 1, except that 1 g of maleic acid monomer is added in step (5) and the following steps are consistent with example 1:

[0172] Add 10 g of acrylamide (AM) and 1 g of maleic acid monomer into the 99 g emulsion of step (4) and mix well.

[0173] Example 19 (no self-healing)

[0174] This example provides a temperature-sensitive composite hydrogel (sample 19) which is prepared in a similar manner to example 1, and specifically includes the following steps:

[0175] (1) Prepare a 0.24 wt% carboxymethyl cellulose solution of 400 g.

[0176] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM) and mix well.

[0177] (3) Add 0.33 g of crosslinking agent N,N'-methylene bisacrylamide, and after the solution is fully stirred and transparent, heat to 70°C.

[0178] (4) Add 0.165 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, start the reaction, and during the reaction, continuously stir and purge nitrogen to remove oxygen, and react for 30 min to obtain a uniformly dispersed emulsion.

[0179] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic acid monomer into the 98.5 g emulsion of step (4) and mix well.

[0180] (6) Add 0.5 g of crosslinking agent N,N'-methylene bisacrylamide, and add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, and place in a 1 mm mold, start the reaction in a high temperature 65°C environment, and react for 30 min to obtain a temperature-sensitive hydrogel, which is sample 19.

[0181] Example 20 (change the concentration of temperature-sensitive polymer)

[0182] This embodiment provides a self-healing temperature-sensitive composite hydrogel, and this embodiment also provides a method for preparing the self-healing temperature-sensitive composite hydrogel, characterized by the following steps:

[0183] (1) Prepare 400g of 0.02wt% carboxymethyl cellulose solution.

[0184] (2) Add 2g of N-isopropylacrylamide (NIPAM) and 0.2g of dimethylaminoethyl methacrylate (DMAEMA) and mix thoroughly.

[0185] (3) Add 0.042g of crosslinking agent N,N'-methylenebisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70℃.

[0186] (4) Add 0.0212 g each of ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride to start the reaction. During the reaction, nitrogen is purged to remove oxygen and the mixture is stirred continuously. After 30 min, a uniformly dispersed emulsion is obtained.

[0187] (5) Add 10g of acrylamide (AM) and 1g of acrylic monomer to the 99g emulsion in step (4) and stir to mix evenly.

[0188] (6) Add 0.055 g each of initiator ammonium persulfate and 2,2'-azobisisobutylamidine dihydrochloride, place them in a 10 mm mold, and start the reaction at a high temperature of 65 °C. After reacting for 30 min, a thermosensitive self-healing hydrogel is obtained, which is recorded as sample 20.

[0189] Appendix Figure 5 The graph shows the temperature change of a phase-change blackbody, where the blackbody simulates indoor temperature and the xenon lamp simulates sunlight. The curve corresponding to sample 20 in the graph is black. As can be seen from the graph, the temperature of sample 20 increases significantly at 1200 s, losing its ability to maintain room temperature.

[0190] Example 21 (Changing the concentration of the temperature-sensitive polymer)

[0191] This embodiment provides a self-healing temperature-sensitive composite hydrogel, and this embodiment also provides a method for preparing the self-healing temperature-sensitive composite hydrogel, characterized by the following steps:

[0192] (1) Prepare 400g of 0.24wt% carboxymethyl cellulose solution.

[0193] (2) Add 24g of N-isopropylacrylamide (NIPAM) and 1.2g of dimethylaminoethyl methacrylate (DMAEMA) and mix thoroughly.

[0194] (3) Add 0.252 g of crosslinking agent N,N'-methylene bisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0195] (4) Add 0.128 g of initiator ammonium persulfate and 2,2'-azobisdimethylvaleric acid dihydrochloride, respectively, start the reaction, and continuously stir while purging oxygen with nitrogen during the reaction, and react for 30 min to obtain a uniformly dispersed emulsion.

[0196] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic monomer to the 99 g emulsion of step (4), and mix uniformly.

[0197] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylvaleric acid dihydrochloride, respectively, and place in a 1 mm mold, start the reaction in a high-temperature 65°C environment, and react for 30 min to obtain a temperature-sensitive self-healing hydrogel, which is recorded as sample 21.

[0198] Example 22 Change the concentration of temperature-sensitive polymers

[0199] The present embodiment provides a self-healing temperature-sensitive composite hydrogel, and the present embodiment provides a preparation method of a self-healing temperature-sensitive composite hydrogel, characterized in that it specifically comprises the following steps:

[0200] (1) Prepare a 0.4 wt% carboxymethyl cellulose solution of 400 g.

[0201] (2) Add 44 g of N-isopropyl acrylamide (NIPAM) and 2.2 g of dimethylaminoethyl methacrylate (DMAEMA), and mix thoroughly.

[0202] (3) Add 0.462 g of crosslinking agent N,N'-methylene bisacrylamide, stir thoroughly until the solution is transparent, and then heat to 70°C.

[0203] (4) Add 0.235 g of initiator ammonium persulfate and 2,2'-azobisdimethylvaleric acid dihydrochloride, respectively, start the reaction, and continuously stir while purging oxygen with nitrogen during the reaction, and react for 30 min to obtain a uniformly dispersed emulsion.

[0204] (5) Add 10 g of acrylamide (AM) and 1 g of acrylic monomer to the 99 g emulsion of step (4), and mix uniformly.

[0205] (6) Add 0.055 g of initiator ammonium persulfate and 2,2'-azobisdimethylvaleric acid dihydrochloride, respectively, and place in a 0.5 mm mold, start the reaction in a high-temperature 65°C environment, and react for 30 min to obtain a temperature-sensitive self-healing hydrogel, which is recorded as sample 22.

[0206] Example 23 Change the amount of CMC to control the particle size

[0207] The embodiment provides a self-healing temperature-sensitive composite hydrogel, and the embodiment provides a preparation method of the self-healing temperature-sensitive composite hydrogel.

[0208] (1) 400 g of a 0.06 wt% carboxymethyl cellulose solution is prepared.

[0209] (2) 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA) and 7.5 g of acrylamide (AM) are added and uniformly mixed.

[0210] (3) 0.33 g of a crosslinking agent N,N'-methylene bisacrylamide is added, and after the solution is fully stirred and transparent, heating is performed to 70 DEG C.

[0211] (4) 0.165 g of each of initiators ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride are added, and the reaction is started, during which nitrogen is passed to remove oxygen and stirring is not stopped, and the reaction is performed for 30 min, to obtain a uniformly dispersed emulsion.

[0212] (5) 10 g of acrylamide (AM) and 1 g of acrylic acid monomer are added to the 99 g emulsion in step (4) and uniformly mixed.

[0213] (6) 0.055 g of each of initiators ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride is added, and the reaction is started in a 1 mm mold at a high temperature of 65 DEG C, and the reaction is performed for 30 min, to obtain a temperature-sensitive self-healing hydrogel, which is recorded as sample 23.

[0214] The particle size of the emulsion at 25 DEG C is about 0.836 microns during the preparation of the sample.

[0215] Example 24

[0216] The embodiment provides a self-healing temperature-sensitive composite hydrogel, and the embodiment provides a preparation method of the self-healing temperature-sensitive composite hydrogel.

[0217] (1) 400 g of a 0.12 wt% carboxymethyl cellulose solution is prepared.

[0218] (2) 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA) and 7.5 g of acrylamide (AM) are added and uniformly mixed.

[0219] (3) 0.33 g of a crosslinking agent N,N'-methylene bisacrylamide is added, and after the solution is fully stirred and transparent, heating is performed to 70 DEG C.

[0220] (4) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.165 g, start the reaction, nitrogen is blown to remove oxygen and stirring is not stopped during the reaction, and the reaction is carried out for 30 min to obtain a uniformly dispersed emulsion.

[0221] (5) 10 g of acrylamide (AM) and 1 g of acrylic acid monomer are added to the 99 g emulsion of step (4) and stirred and mixed uniformly.

[0222] (6) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.055 g, put into a 1 mm mold, start the reaction in a high temperature 65℃ environment, and the reaction is carried out for 30 min to obtain a temperature-sensitive self-healing hydrogel, which is recorded as sample 24.

[0223] The particle size of the emulsion at 25℃ is about 0.751 microns during the preparation of this sample.

[0224] Example 25

[0225] The present embodiment provides a self-healing temperature-sensitive composite hydrogel, and the present embodiment provides a preparation method of a self-healing temperature-sensitive composite hydrogel, which is characterized by comprising the following steps:

[0226] (1) Prepare a 0.18wt% carboxymethyl cellulose solution of 400 g.

[0227] (2) Add 24 g of N-isopropyl acrylamide (NIPAM), 1.2 g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5 g of acrylamide (AM), and mix thoroughly.

[0228] (3) Add 0.33 g of crosslinking agent N,N'-methylene bisacrylamide, and stir thoroughly until the solution is transparent, and then heat to 70℃.

[0229] (4) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.165 g, start the reaction, nitrogen is blown to remove oxygen and stirring is not stopped during the reaction, and the reaction is carried out for 30 min to obtain a uniformly dispersed emulsion.

[0230] (5) 10 g of acrylamide (AM) and 1 g of acrylic acid monomer are added to the 99 g emulsion of step (4) and stirred and mixed uniformly.

[0231] (6) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.055 g, put into a 1 mm mold, start the reaction in a high temperature 65℃ environment, and the reaction is carried out for 30 min to obtain a temperature-sensitive self-healing hydrogel, which is recorded as sample 25.

[0232] The particle size of the emulsion at 25℃ is about 0.653 microns during the preparation of this sample.

[0233] Example 26

[0234] The present embodiment provides a self-healing temperature-sensitive composite hydrogel, and the present embodiment provides a preparation method of the self-healing temperature-sensitive composite hydrogel, which is characterized by comprising the following steps:

[0235] (1) Prepare a 0.30wt% carboxymethyl cellulose solution of 400g.

[0236] (2) Add 24g of N-isopropyl acrylamide (NIPAM), 1.2g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5g of acrylamide (AM), and mix thoroughly.

[0237] (3) Add 0.33g of crosslinking agent N,N'-methylene bisacrylamide, and heat to 70°C after thorough stirring until the solution is transparent.

[0238] (4) Add 0.165g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, start the reaction, and continuously stir and deoxygenate with nitrogen during the reaction, and react for 30min to obtain a uniformly dispersed emulsion.

[0239] (5) Add 10g of acrylamide (AM) and 1g of acrylic acid monomer to the 99g emulsion of step (4), and mix thoroughly.

[0240] (6) Add 0.055g of initiator ammonium persulfate and 2,2'-azobisdimethylaminoethyl methacrylate dihydrochloride, and place it in a 1mm mold, start the reaction in a high-temperature 65°C environment, and react for 30min to obtain a temperature-sensitive self-healing hydrogel, which is recorded as sample 26.

[0241] The particle size of the emulsion at 25°C is about 0.483 microns during the preparation of this sample

[0242] Example 27

[0243] The present embodiment provides a self-healing temperature-sensitive composite hydrogel, and the present embodiment provides a preparation method of the self-healing temperature-sensitive composite hydrogel, which is characterized by comprising the following steps:

[0244] (1) Prepare a 0.36wt% carboxymethyl cellulose solution of 400g.

[0245] (2) Add 24g of N-isopropyl acrylamide (NIPAM), 1.2g of dimethylaminoethyl methacrylate (DMAEMA), and 7.5g of acrylamide (AM), and mix thoroughly.

[0246] (3) Add 0.33g of crosslinking agent N,N'-methylene bisacrylamide, and heat to 70°C after thorough stirring until the solution is transparent.

[0247] (4) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.165g, start reaction, during the period of nitrogen to remove oxygen and do not stop stirring, reaction 30min, get uniform dispersion emulsion.

[0248] (5) Add 10g acrylamide (AM), 1g acrylic acid monomer to 99g emulsion in step (4), stir and mix evenly.

[0249] (6) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.055g, put into 1mm mold, start reaction in high temperature 65℃ environment, reaction 30min, get temperature-sensitive self-healing hydrogel, recorded as sample 27.

[0250] The particle size of the emulsion measured during the preparation of this sample is about 0.423 microns at 25℃

[0251] Example 28 (direct polymerization without using emulsion)

[0252] This example provides a traditional temperature-sensitive composite hydrogel (sample 28), which is prepared without using emulsion polymerization, including the following steps:

[0253] (1) Add 24g N-isopropyl acrylamide (NIPAM) to 400g water, mix well.

[0254] (2) Add 10g acrylamide (AM) and 0.33g crosslinking agent N,N'-methylene bisacrylamide to 99g solution in step (2), stir and mix evenly.

[0255] (3) Add initiator ammonium persulfate and 2,2'-azobis (isobutyrylimide) dihydrochloride each 0.17g, put into 1mm mold, start reaction in high temperature 65℃ environment, reaction 30min, get traditional temperature-sensitive self-healing hydrogel.

[0256] Appendix Figure 2 The effect picture of volume shrinkage of sample 28 hydrogel after multiple high-low temperature cycles.

[0257] Example 29 (direct polymerization without using temperature-sensitive monomer)

[0258] This example provides a method for preparing a common non-temperature-sensitive hydrogel (sample 29), including the following steps:

[0259] (1) Add 10g acrylamide (AM) to 99g water, stir and mix evenly.

[0260] (2) Add 0.5 g of crosslinking agent N,N'-methylene bisacrylamide, add 0.01 g of initiator ammonium persulfate and 2,2'-azobis isobutyl imidamide dihydrochloride respectively, put into 1 mm mold, start reaction in high temperature 65℃ environment, reaction for 30 min, get ordinary hydrogel.

[0261]

Claims

1. A method for preparing a self-healing thermosensitive hydrogel, characterized in that, Specifically, the following steps are included: 1) Prepare an aqueous solution of carboxymethyl cellulose; 2) Add N-isopropylacrylamide, cationic monomer, and acrylamide monomer to the solution in step 1), and mix thoroughly. The mass ratio of N-isopropylacrylamide, cationic monomer, and acrylamide monomer is 100:1~10:10~50. The cationic monomer is any one or a combination of DMAEMA, N,N-diethylaminoethyl acrylate, MATAC, 4-dimethylaminostyrene, 4-vinylpyridine, N,N-dimethylallylamine, N,N-diethylallylamine, diallylmethylamine, triallylamine, and 2-(dimethylamino)ethyl acrylate. 3) Add the crosslinking agent N,N'-methylenebisacrylamide to 2), stir thoroughly until the solution becomes clear, and then heat and stir. 4) Add the initiator while heating and stirring, and stir the reaction under nitrogen to obtain a uniformly dispersed emulsion, in which the thermosensitive polymer particles contain cations in their molecular chains; 5) Add acrylamide and anionic monomer to the emulsion obtained in step 4), stir and mix evenly to obtain a mixture; 6) Add an initiator to the mixture obtained in step 5), put it into a mold, heat it to polymerize, and obtain a thermosensitive self-healing hydrogel.

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

3. 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-methylpropanesulfonic acid.

4. The preparation method according to claim 1, characterized in that, The concentration of the prepared carboxymethyl cellulose aqueous solution is 0.02~0.36wt%.

5. The self-healing thermosensitive hydrogel prepared according to any one of claims 1-4, characterized in that, The self-healing thermosensitive hydrogel particle content ranges from 0.5% to 10%. The self-healing thermosensitive hydrogel with different thermosensitive polymer contents can regulate the visible light after the thermosensitive hydrogel changes color according to the thickness.

6. The application of the self-healing thermosensitive hydrogel according to claim 5 in smart windows.

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