Preparation method of high-solid-content dual-network polyacrylamide / polyvinyl alcohol composite gel

Abstract

The invention discloses a preparation method of high-solid-content dual-network polyacrylamide / polyvinyl alcohol composite gel, which comprises the following steps: by taking polyvinyl alcohol as a raw material, firstly heating and dissolving the polyvinyl alcohol in a solvent, then adding acrylamide, polyethylene glycol diacrylate and 2, 2 '-azobis (isobutylamidine) dihydrochloride into a polyvinyl alcohol solution, and after all the components are dissolved, adding a cross-linking agent and a cross-linking agent, so as to obtain the high-solid-content dual-network polyacrylamide / polyvinyl alcohol composite gel. The preparation method comprises the following steps: dropwise adding a boric acid-ethylene glycol solution while mechanically stirring, then adding solid particles, uniformly mixing, transferring to a glass mold, and carrying out thermal initiation in an environment of 50-60 DEG C, thereby constructing the double-network composite gel with excellent mechanical properties and high solid particle content. The method is simple and easy to implement, the adjustable range of the loading capacity of the solid particles is wide, the shape and size of the composite gel can be directionally selected according to a mold, the prepared composite gel has certain stability and mechanical performance, and a new thought and method are provided for preparing the micro-nano particle composite gel material.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation, and relates to a method for preparing a composite gel material, in particular to a method for preparing a high-solid content double-network polyacrylamide / polyvinyl alcohol composite gel. Background Art

[0002] Organic hydrogel materials have been widely studied and applied in the field of materials science due to their unique three-dimensional cross-linked structure, adjustable physical properties, and excellent biocompatibility and environmental adaptability. In recent years, researchers have introduced inorganic micro- and nano-solid particles such as gold, silver, zinc oxide, and ferroferric oxide into gel systems to produce composite gel materials. This not only changes the mechanical properties of the gel but also imparts functional properties such as magnetism, electrical conductivity, thermal conductivity, and optical properties to the material, making the application prospects of composite gel materials in fields such as sensors, electronic skin, soft robotics, and biomedicine increasingly broad. For composite materials to have excellent functionality, a high filler loading is generally required. For example, excellent thermal conductivity requires a filler loading greater than 50%. More magnetic particles can improve the magnetic-mechanical coupling performance of magnetic composites, while more antibacterial particles and conductive fillers can enhance their corresponding functionality.

[0003] As the particle content increases, how to ensure the uniform distribution of particles and avoid particle sedimentation or agglomeration has always been a major challenge facing composite gel materials. At the same time, for practical applications, composite gels need to have appropriate mechanical properties, and the gel as a substrate for supporting particles is crucial to the mechanical properties of composite gels. With the growing demand for highly functional composite materials, the limitations of traditional gel materials have become increasingly apparent, especially when it is necessary to enhance the physical properties of the gel and the functionality of the composite material. A single gel system often cannot meet these requirements. In recent years, people have explored a variety of strategies for preparing new organic hydrogels with excellent mechanical properties, including double network (DN) gels, sliding ring hydrogels, and microsphere hydrogels. Among them, the DN gel strategy has been widely used in the preparation of composite gels to optimize mechanical properties.

[0004] Researchers have developed PNaAMPS / PAAM / Laponite / NdFeB magnetic composite gel materials through 3D printing. Microgel powder prepared by polymerization of 2-acrylamide-2-methylpropanesulfonic acid (NaAMPS), nanoclay (Laponite), acrylamide (AM) monomer and its crosslinker and initiator, and 5μm neodymium iron boron (NdFeB) (accounting for 50% of the total weight of acrylamide and deionized water, and approximately 33.33% of the total mass) are blended and made using 3D printing. The embedding of hard magnetic NdFeB gives the material programmable complex deformation in response to an external magnetic field. The addition of microgel and nanoclay is used to increase the viscosity of the precursor and prevent the sedimentation of NdFeB particles. The participation of microgel forms a dual network topology structure, which is used to improve the mechanical properties of magnetic hydrogels (Advanced Intelligent Systems, 2022, 4(1): 2100139.). The double network structure is prepared based on the first synthesis of microgels. The gel base of the composite gel is not a uniform double network structure. Moreover, the use of 3D printing to prepare composite gels requires precise control of the mixing ratio of multiple materials, printing parameters, etc. This method is more suitable for laboratory tests. In addition, based on the Hoffmeister effect and the toughening method of double network hydrogels, the researchers prepared a Fe3O4 / CS (chitosan)-PAAM double network electromagnetically conductive responsive hydrogel with ultra-high toughness through ionic crosslinking, molecular entanglement, and hydrogen bond enhancement between nanoparticles and polymer networks. The magnetic particle content can reach 43wt% (43% is relative to the total weight of polymer and water, accounting for approximately 30.07% of the total mass). The modulus of the prepared hydrogel is 1.3MPa, and the toughness exceeds 54KJ / m 2 . The addition of chitosan not only increases the viscosity of the precursor and prevents particle sedimentation, but also forms a double network substrate together with the PAAM network, optimizing the mechanical properties of the composite gel (Composites Part A: Applied Science and Manufacturing, 2023, 168: 107478.). This method involves multiple interactions, and the preparation process requires precise control of each reaction condition, which places high demands on the experimental equipment and professional skills of the operator; the price of chitosan is relatively high, and the material preparation cost is high; it is not conducive to industrial production. The solid particle loading of the composite gel obtained by the above two methods is about 30% of the total mass, the solid particle loading is limited, and the application scenarios are limited. Summary of the Invention

[0005] In view of the common problems of existing composite gels, such as difficulty in loading high-content solid particles, uneven particle distribution and poor mechanical properties, the present invention provides a method for preparing a high-solid-content double-network polyacrylamide / polyvinyl alcohol composite gel. The method is based on improving the uniformity and stability of the solid particle gel precursor mixture by increasing the viscosity of the system, optimizing the mechanical properties of the gel based on the concept of hybrid double network, and developing high-content micro-nano particle gel materials. Taking the loading of zinc oxide solid particles as an example, a polyvinyl alcohol-borax dynamic cross-linking network and a polyacrylamide chemical cross-linking network are selected to jointly construct the gel base, and finally a hybrid double-network high-content micro-nano particle gel composite material with uniform solid particle distribution and excellent mechanical properties is obtained. The present invention is simple and easy to implement, the loading amount of solid particles can be adjusted in a wide range, the shape and size of the composite gel can be selected according to the mold, and the prepared composite gel has certain stability and mechanical properties.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a high-solid content double-network polyacrylamide / polyvinyl alcohol composite gel comprises the following steps:

[0008] Step 1: adding polyvinyl alcohol to a solvent and heating and dissolving it to obtain a polyvinyl alcohol solution, wherein: the solvent is ethylene glycol or water, the heating and dissolving temperature is 70-80° C., and the concentration of the polyvinyl alcohol solution is 3-10%;

[0009] Step 2: adding acrylamide, polyethylene glycol diacrylate and 2,2'-azobisisobutylamidine dihydrochloride to the polyvinyl alcohol solution obtained in step 1 in sequence to obtain a uniform mixed solution, wherein: the amount of acrylamide added is 40-100% of the molar amount of the polyvinyl alcohol repeating unit, the amount of polyethylene glycol diacrylate added is 0.4-1% of the molar amount of the acrylamide, and the amount of 2,2'-azobisisobutylamidine dihydrochloride added is 1-2% of the molar amount of the acrylamide;

[0010] Step 3: Adding a borax-ethylene glycol solution dropwise to the uniform mixed solution obtained in step 2 to obtain a mixed solution having dynamic crosslinking sites, wherein the concentration of the borax-ethylene glycol solution is 7-20%, and the amount added is 0.4-2% of the molar amount of the polyvinyl alcohol repeating unit;

[0011] Step 4: adding solid particles in batches to the mixed solution having dynamic crosslinking sites obtained in step 3 to obtain a solid-liquid mixed system, wherein the solid particles are one of zinc oxide, ferroferric oxide, cobalt oxide, iron powder, etc., and the amount added is 50-85% of the total mass of the solid-liquid mixed system;

[0012] Step 5: Transfer the solid-liquid mixed system obtained in step 4 to a glass mold sprayed with a release agent, and place it in an oven for thermally initiated polymerization to obtain a high-solid content double-network polyacrylamide / polyvinyl alcohol composite gel, wherein: the oven temperature is 50-60°C, and the thermally initiated polymerization reaction time is 4-8h.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] The composite gel constructed in the present invention can have a zinc oxide solid particle loading of up to 85%. The solid particles are evenly dispersed, and the composite gel has a certain degree of stability. Furthermore, the solid particle loading is not limited to zinc oxide, and can also support the loading of other types or mixtures of multiple types of solid particles.

[0015] 2. The composite gel constructed by the present invention has certain strength and toughness.

[0016] 3. The composite gel constructed by the present invention has a wide adjustable range of performance. By rationally designing the ratio between the dual networks and the content of each substance, the overall mechanical properties of the composite gel can be adjusted.

[0017] 4. The viscosity of polyvinyl alcohol-borax can be adjusted in a wide range, which supports the dispersion of large-sized solid particles and avoids sedimentation. At the same time, it has the characteristics of shear thinning, which facilitates the uniform dispersion of solid particles in the system during the preparation process.

[0018] 5. The preparation method of the present invention is simple, easy to scale up for preparation, has strong stability during operation, and has practical application prospects and sustainability.

[0019] 6. In order to overcome the problem of uniform distribution of solid particles in high-content micro-nano particle gel composite materials and ensure good mechanical properties of the composite materials, the present invention constructs a high-content micro-nano particle composite gel material based on the conceptual design of hybrid double networks, which ensures that a large number of solid particles are uniformly distributed in the system while having good mechanical properties, providing a new idea and method for the preparation of micro-nano particle composite gel materials.

[0020] 7. The present invention is expected to develop composite gel materials with high practical value in many fields, including but not limited to high-solid content gel propellants, high-solid content conductive hydrogels, high-solid content magnetron gels, etc., showing important application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 These are photos of composite gel precursor mixtures with solid contents of 50%, 60%, 70%, 80%, and 85% (first row) and photos of composite gels with solid contents of 50%, 60%, 70%, 80%, and 85% (second row).

[0022] Figure 2 These are photos of swelling tests of composite gels with solid contents of 70% and 85%.

[0023] Figure 3 These are the Fourier transform infrared spectra of the double network gel and composite gel.

[0024] Figure 4 These are the thermogravimetric curves of composite gels with solid contents of 50%, 60%, 70%, 80%, and 85%.

[0025] Figure 5 These are SEM images of composite gels with solid contents of 50%, 60%, 70%, 80%, and 85%.

[0026] Figure 6 This is the element distribution diagram of composite gel with solid content of 50% and 80%.

[0027] Figure 7 It is a uniaxial stress-strain curve diagram of composite gel with solid content of 50%, 60%, 70%, 80% and 85%.

[0028] Figure 8 These are photos of composite gels with solid contents of 50%, 60%, 70%, 80%, and 85% before, during, and after compression.

[0029] Figure 9 These are the compression force-displacement curves and stress-strain curves of composite gels with solid contents of 50%, 60%, 70%, 80% and 85%. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below with reference to the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0031] The present invention provides a method for preparing a high solid content double network polyacrylamide / polyvinyl alcohol composite gel. The method uses polyvinyl alcohol as a raw material, firstly heats and dissolves the polyvinyl alcohol in a solvent, and then adds acrylamide and polyethylene glycol diacrylate (M n =700g / mol), 2,2'-azobisisobutylamidine dihydrochloride, after all dissolved, adding boric acid-ethylene glycol solution dropwise while mechanically stirring, then adding solid particles, mixing evenly, transferring the mixture to a glass mold, placing it in an environment of 50-60°C for thermal initiation, thereby constructing a double-network composite gel with excellent mechanical properties and high solid particle content, which specifically includes the following steps:

[0032] Step 1: Add polyvinyl alcohol to a solvent, heat and dissolve in an oil bath to obtain a polyvinyl alcohol solution, wherein: the solvent is ethylene glycol or water, the oil bath temperature is 70-80° C., and the mass concentration of the polyvinyl alcohol solution is 3-10%.

[0033] Step 2: Add borax to ethylene glycol and dissolve it in an ultrasonic cleaner for a period of time to obtain a borax-ethylene glycol (Borax-EG) solution, wherein the mass concentration of the borax-ethylene glycol solution is 7-20%.

[0034] Step 3: adding acrylamide, polyethylene glycol diacrylate and 2,2'-azobisisobutylamidine dihydrochloride in sequence to the polyvinyl alcohol solution obtained in step 1, and stirring to obtain a uniform solution, wherein: the amount of acrylamide added is 40-100% of the molar amount of the polyvinyl alcohol repeating unit, the amount of polyethylene glycol diacrylate added is 0.4-1% of the molar amount of acrylamide, and the amount of 2,2'-azobisisobutylamidine dihydrochloride added is 1-2% of the molar amount of acrylamide.

[0035] Step 4: Using mechanical stirring, while simultaneously adding a borax-ethylene glycol solution to the uniformly mixed solution obtained in Step 3, a uniform mixed solution with dynamic crosslinking sites is obtained. The amount of borax-ethylene glycol solution added is 0.4-2% of the molar weight of the polyvinyl alcohol repeating unit. The addition of the borax-ethylene glycol solution in this step creates dynamic crosslinking sites in the polyvinyl alcohol, which increases the viscosity of the precursor solution. Furthermore, because the bonds at the crosslinking sites in the dynamic crosslinking network can reversibly break and rebond, the network exhibits shear-thinning properties. This allows the solid particles to be evenly dispersed in the gel precursor mixture. When the external force is removed, the viscosity of the system rises sharply, preventing particle aggregation.

[0036] Step 5: Continue stirring by mechanical stirring, and add solid particles in small amounts and batches to the mixed solution with dynamic cross-linking sites obtained in step 4. After mixing evenly, stop mechanical stirring to obtain a solid-liquid mixed system, wherein: the solid particles are one of zinc oxide (diameter of about 1 μm), ferrosoferric oxide, cobalt oxide, aluminum powder, iron powder, etc., and the addition amount is 50-85% of the total mass of the solid-liquid mixed system.

[0037] Step 6: The solid-liquid mixture obtained in Step 5 is transferred to a glass mold sprayed with a release agent and placed in an oven for thermal polymerization to produce a high-solids composite gel with specific mechanical properties and stability. The oven temperature is 50-60°C and the thermal polymerization reaction time is 4-8 hours. In this step, the addition of a large amount of zinc oxide, through chemical crosslinking, imparts a stable structure and specific mechanical properties to the system, resulting in a hybrid double-network high-content micro-nanoparticle gel composite material with uniform solid particle distribution and excellent mechanical properties.

[0038] Example 1:

[0039] At room temperature and pressure, add 1g of polyvinyl alcohol to 12ml of ethylene glycol, heat in an oil bath at 70℃, stir and dissolve to obtain a polyvinyl alcohol solution; take 2g of polyvinyl alcohol solution, add 0.213g of acrylamide, 0.011g of polyethylene glycol diacrylate, and 0.012g of 2,2'-azobisisobutylamidine dihydrochloride in sequence, and stir to obtain a uniform solution; start mechanical stirring, add 15μl of 0.2g / ml borax-ethylene glycol solution dropwise, and stir until uniform; add 2.239g / 3.359 g / 5.224 g / 8.956 g / 12.688 g of 1 μm zinc oxide were added thereto and stirred evenly before stopping the mechanical stirring; the uniform mixture was then transferred to a glass mold sprayed with a release agent, placed in an oven at 50°C for 4 hours to initiate thermal polymerization, and removed from the mold to obtain composite gels having a specific shape, good mechanical properties, and good stability, with solid contents of approximately 50%, 60%, 70%, 80%, and 85% (the characterization data below are based on the materials obtained in this example).

[0040] Example 2:

[0041] At room temperature and pressure, 1 g of polyvinyl alcohol is added to 10 ml of deionized water, and the mixture is heated and stirred in an oil bath at 70°C to dissolve the polyvinyl alcohol aqueous solution; 2 g of the polyvinyl alcohol aqueous solution is added sequentially with 0.284 g of acrylamide, 0.028 g of polyethylene glycol diacrylate, and 0.011 g of 2,2'-azobisisobutylamidine dihydrochloride, and stirred to obtain a uniform solution; mechanical stirring is turned on, and 25 μl of a 0.2 g / ml borax-ethylene glycol solution is added dropwise, and the mixture is stirred until uniform; 5.537 g of 1 μm zinc oxide is added, stirred until uniform, and the mechanical stirring can be stopped; the uniform mixture is then transferred to a glass mold sprayed with a release agent, placed in a 50°C oven for 6 hours to initiate thermal polymerization, and removed from the mold to obtain a composite gel with a specific shape, good mechanical properties, good stability, and a solid content of approximately 70%.

[0042] Example 3:

[0043] At room temperature and pressure, 1 g of polyvinyl alcohol is added to 14 ml of ethylene glycol, and the mixture is heated and stirred in an 80°C oil bath to dissolve to obtain a polyvinyl alcohol solution; 2 g of the polyvinyl alcohol solution is taken, and 0.355 g of acrylamide, 0.018 g of polyethylene glycol diacrylate, and 0.014 g of 2,2'-azobisisobutylamidine dihydrochloride are added thereto in sequence, and stirred to obtain a uniform solution; mechanical stirring is turned on, and 60 μl of a 0.2 g / ml borax ethylene glycol solution is added dropwise, and the mixture is stirred until uniform; 2.399 g of 1 μm zinc oxide is added thereto, and the mixture is stirred until uniform and the mechanical stirring can be stopped; the uniform mixture is then transferred to a polytetrafluoroethylene mold sprayed with a release agent, placed in a 60°C oven for 6 hours to initiate thermal polymerization, and removed from the mold to obtain a composite gel with a specific shape, good mechanical properties, good stability, and a solid content of approximately 50%.

[0044] Example 4:

[0045] At room temperature and pressure, 1 g of polyvinyl alcohol is added to 11 ml of ethylene glycol, and the mixture is heated and stirred in an oil bath at 70°C to dissolve the mixture to obtain a polyvinyl alcohol solution; 2 g of the polyvinyl alcohol solution is added sequentially with 0.320 g of acrylamide, 0.015 g of polyethylene glycol diacrylate, and 0.012 g of 2,2'-azobisisobutylamidine dihydrochloride, and stirred to obtain a uniform solution; mechanical stirring is started, and 30 μl of a 0.2 g / ml borax-ethylene glycol solution is added dropwise, and the mixture is stirred until uniformly mixed; 5.49 g of 500 nm ferrosoferric oxide is added, stirred until uniformly mixed, and the mechanical stirring can be stopped; the uniform mixture is then transferred to a glass mold sprayed with a release agent, placed in a 50°C oven for 4 hours to initiate thermal polymerization, and removed from the mold to obtain a composite gel with a specific shape, good mechanical properties, good stability, and a solid content of approximately 70%.

[0046] Depend on Figure 1 As can be seen in the first row, a batch of gel precursor mixtures with varying zinc oxide content (50, 60, 70, 80, and 85%) were mixed. As the solid particle content increased, the mixture's state gradually changed from a fluid state to a paste and finally a doughy state. Each precursor mixture was heated to induce acrylamide polymerization and cross-linking to produce a composite gel material. This composite gel was uniformly formed into sheets with a diameter of 20 mm and a thickness of 1 mm. As shown in the second row, the softness of the composite gel gradually decreased with increasing solid content.

[0047] Depend on Figure 2 It can be seen that the composite gel material was subjected to a swelling test. The composite gel materials with ZnO contents of 70% and 85% were immersed in deionized water and ethylene glycol for 24 hours respectively. The materials swelled but did not dissolve, which is consistent with the characteristics of the gel.

[0048] Figure 3The infrared spectra of 0%, 60%, 70%, and 80% ZnO / PAAM / PVA-Borax composite gels are shown in Figure 2. For PAAM / PVA-Borax gel, the peaks at 3369, 1616, 1323, and 1087 cm -1 The absorption peaks at 500cm are caused by the stretching vibration, NH bending vibration, NH2 in-plane shear vibration and NH plane vibration of OH of PVA and PAAM respectively. -1 A clear absorption peak appears near the Zn-O bending vibration peak. Simultaneously, the vibration peaks of OH and NH undergo a significant red shift, indicating hydrogen bonding interactions with the zinc oxide particles. The red shift becomes more pronounced as the amount of zinc oxide increases. These results demonstrate the successful preparation of the zinc oxide double-network composite gel and the presence of hydrogen bonding interactions between the double networks and the zinc oxide particles.

[0049] Depend on Figure 4 It can be seen that the double-network composite gel materials with different contents of zinc oxide were subjected to thermogravimetric characterization. The composite gels with different solid contents showed two weight loss platforms as the temperature increased in the TGA test. In the temperature range of 30 to 195°C, the gel composite first desolvated and volatilized the small molecule components. Starting from around 195°C, the high molecular weight polymer in the material gradually began to oxidatively decompose, and the mass reached the lowest value at around 500°C. At this time, the residue was mainly zinc oxide. It can be seen from the proportion of components that the composite material is composed of a gel matrix and a certain amount of solid particles, and the content of solid particles can be as high as 85% of the total mass.

[0050] The present invention uses SEM to observe the microstructure of the cross section of the ZnO / PAAM / PVA-Borax gel composite material after liquid nitrogen freeze-drying. Figure 5 The following are SEM images of cross-sections of ZnO double-network gel composites with different contents (50, 60, 70, 80, and 85%). It can be seen from the images that the interaction between the solid particles and the gel matrix results in a dense, uniform, and continuous material.

[0051] In order to prove the uniformity of the material structure from a microscopic perspective, the element distribution characterization analysis of the ZnO / PAAM / PVA-Borax composite gel material after liquid nitrogen freeze-drying was further carried out. Figure 6 The C, N, O, and Zn elements on the uneven cross-sectional surface are uniform in color and evenly distributed, which to some extent indicates that the hybrid double-network gel material is uniformly loaded with a large number of zinc oxide solid particles.

[0052] Figure 7The following are uniaxial tensile stress-strain curves for ZnO / PAAM / PVA-Borax composite gels with zinc oxide contents of 50, 60, 70, 80, and 85%, respectively. As can be seen, the slope of the curve increases significantly with increasing solid particle content in the composite gel, indicating that the zinc oxide particles strengthen the gel. Furthermore, more zinc oxide occupies more space in the gel network, making it more crowded and disordered. This makes it less likely to deform significantly during stretching and more prone to fracture.

[0053] Figure 8 The following are photos of the compression process of ZnO / PAAM / PVA-Borax composite gel materials with zinc oxide contents of 50%, 60%, 70%, 80%, and 85%, respectively. The images are taken before compression (1), under a load of 100 N (2), and 2 minutes after unloading (3). As can be seen from the figure, as the zinc oxide content increases, the degree of deformation of the material under a load of 100 N decreases, indicating that deformation becomes increasingly difficult and the compression modulus increases.

[0054] Figure 9 The following are the compression force-displacement and stress-strain curves of the material during compression. As can be seen from the figure, the curves exhibit typical nonlinear characteristics. As displacement increases, the curves gradually bend upward, and the compression force continues to increase. The materials can withstand a compressive stress of 300 kPa without reaching a yield point. With the increase of zinc oxide, the rigidity of the gel system increases, introducing more interactions and increasing the number of crosslinks between molecular chains. The gel network structure becomes tighter and more stable, restricting the freedom of movement of the polyvinyl alcohol and polyacrylamide molecular chains. This improves the resistance to deformation under compression.

Claims

1. A method for preparing a high solid content double network polyacrylamide / polyvinyl alcohol composite gel, characterized in that The method comprises the following steps: Step 1: adding polyvinyl alcohol to a solvent and heating to dissolve it to obtain a polyvinyl alcohol solution with a concentration of 3 to 10%; Step 2: adding acrylamide, polyethylene glycol diacrylate and 2,2'-azobisisobutylamidine dihydrochloride to the polyvinyl alcohol solution obtained in step 1 in sequence to obtain a uniform mixed solution, wherein: the amount of acrylamide added is 40-100% of the molar amount of the polyvinyl alcohol repeating unit, the amount of polyethylene glycol diacrylate added is 0.4-1% of the molar amount of the acrylamide, and the amount of 2,2'-azobisisobutylamidine dihydrochloride added is 1-2% of the molar amount of the acrylamide; Step 3: Adding a borax-ethylene glycol solution dropwise to the uniform mixed solution obtained in step 2 to obtain a mixed solution having dynamic crosslinking sites, wherein the concentration of the borax-ethylene glycol solution is 7-20%, and the amount added is 0.4-2% of the molar amount of the polyvinyl alcohol repeating unit; Step 4: adding solid particles in batches to the mixed solution having dynamic crosslinking sites obtained in step 3 to obtain a solid-liquid mixed system, wherein the amount of solid particles added is 50-85% of the total mass of the solid-liquid mixed system; Step 5: Transfer the solid-liquid mixed system obtained in step 4 to a glass mold sprayed with a release agent, and place it in an oven for thermally initiated polymerization to obtain a high solid content double-network polyacrylamide / polyvinyl alcohol composite gel.

2. The method for preparing the high solid content double network polyacrylamide / polyvinyl alcohol composite gel according to claim 1, characterized in that The solvent is ethylene glycol or water.

3. The method for preparing the high solid content double network polyacrylamide / polyvinyl alcohol composite gel according to claim 1, characterized in that The heating and dissolving temperature is 70-80°C.

4. The method for preparing the high solid content double network polyacrylamide / polyvinyl alcohol composite gel according to claim 1, characterized in that The solid particles are one of zinc oxide, ferroferric oxide, cobalt oxide and iron powder.

5. The method for preparing the high solid content double network polyacrylamide / polyvinyl alcohol composite gel according to claim 1, characterized in that The oven temperature is 50-60°C.

6. The method for preparing the high solid content double network polyacrylamide / polyvinyl alcohol composite gel according to claim 1, characterized in that The thermally initiated polymerization reaction time is 4 to 8 hours.

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