High-toughness hydrogel with interlayer mineralization structure as well as preparation method and application of high-toughness hydrogel

Abstract

The invention belongs to the technical field of hydrogel material preparation, and particularly relates to high-toughness hydrogel with an interlayer mineralization structure and a preparation method and application of the high-toughness hydrogel. The preparation method comprises the following steps: S1, preparing the water-soluble salt and the polymer into a uniform precursor aqueous solution; s2, freezing the precursor aqueous solution into pregel at low temperature; s3, the pre-frozen gel precursor is put into an induction solution for structure induction, and an interlayer mineralization structure is generated. The hydrogel has a remarkable sandwich structure and is composed of an outer compact hydrogel layer, an inner porous hydrogel layer and nano-scale to micron-scale mineral particles dispersed in the whole hydrogel. Due to asymmetry of the compact layer and the porous layer in the deformation process under the action of stress, energy dissipation occurs on a multi-layer interface, so that the energy dissipation level is greatly improved; meanwhile, highly entangled molecular chains and in-situ mineralized minerals can effectively absorb and disperse stress, and then high strength and high toughness are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogel material preparation, and specifically relates to a high-strength and tough hydrogel with a sandwich mineralized structure, and a preparation method and application thereof. Background Art

[0002] The development of hydrogels with excellent mechanical properties has promoted the rapid development of related fields such as flexible electronics, energy devices, soft robotics, and human-machine interfaces. However, due to the loose cross-linking, low solid content, and lack of a hierarchical structure of traditional hydrogels, it is challenging to impart strength, toughness, and tear resistance to them. As a result, hydrogels exhibit fragile properties in practical applications, limiting the in-depth application of their products.

[0003] The key to improving the mechanical properties of hydrogels is to construct an effective energy dissipation mechanism. The main energy dissipation strategies can be divided into three types: topological structure design, such as highly entangled networks and sliding ring structures; sacrificial bond design, including metal coordination bonds and hydrogen bonds; and the incorporation of higher-order structures, such as microphase separation structures, microcrystals and microfibers, strain-induced crystallization, and double-layered structures. Topological structure and sacrificial bond strategies partially alleviate the inherent brittleness of traditional hydrogels under mechanical stress. However, due to the lack of well-organized hierarchical structures from the molecular to the macroscopic scale, it remains challenging to construct hydrogels that can withstand stress failure in certain extreme environments where strength and toughness are required.

[0004] Introducing higher-order structures is one of the most effective methods to enhance the mechanical properties of hydrogels, especially their fracture energy. Current higher-order hydrogels are mainly based on nanoscale or microscale mechanisms, including microcrystals and microfibers or nanolayer structures. Inspired by biomaterials, larger-scale higher-order structures can effectively enhance gel materials, such as the millimeter or submillimeter layered structures of fish scales and shells. However, there is still a lack of effective and simple hydrogels and their preparation methods to achieve efficient reinforcement and toughening based on such large-scale structures. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-strength and tough hydrogel with a sandwich mineralized structure, a preparation method thereof, and an application thereof in order to at least solve one of the problems existing in the current prior art. The hydrogel has a significant sandwich structure, consisting of an outer dense hydrogel layer, an inner porous hydrogel layer, and nano- to micron-sized mineral particles dispersed throughout the hydrogel. The outer dense hydrogel layer and the inner porous hydrogel layer are the same polymer, derived from the same precursor material through a one-step in-situ dynamic evolution. The outer dense hydrogel layer has a high degree of entanglement, a high polymer chain density, and a low water content. The tough dense layer directly and efficiently improves the modulus and strength of the gel. The porous structure of the inner porous hydrogel layer ensures that the hydrogel has a high water content while ensuring the excellent stretchability of the gel as a whole. Due to the asymmetry of the dense layer and the porous layer during deformation under stress, the molecular chains across the interface of the two layers slip and pull out, thereby greatly improving the energy dissipation level, thereby achieving high strength and high toughness. The high degree of entanglement and in-situ mineralization centers of the gel further achieve reinforcement and toughening.

[0006] In order to achieve the above object of the invention, the specific technical solutions of the present invention are as follows:

[0007] A method for preparing a high-strength and tough hydrogel with a sandwich mineralized structure comprises the following steps:

[0008] S1. preparing a water-soluble salt and a polymer into a uniform precursor aqueous solution;

[0009] S2, freezing the precursor aqueous solution obtained in S1 at low temperature to form a pre-gel precursor;

[0010] S3. The gel precursor obtained in S2 is placed in an induction solution for structural induction to produce a sandwich mineralized structure, thereby obtaining a high-strength and tough hydrogel having a sandwich mineralized structure.

[0011] Furthermore, in S1 of the method for preparing a high-strength and tough hydrogel with a sandwich mineralized structure, the water-soluble salt has the ability to induce mineral precipitation with anions or cations in the solution; the total anion concentration is 0.25 to 2 mol / L; and the polymer is a soluble polymer rich in hydrogen bonds.

[0012] Furthermore, the water-soluble salt is a water-soluble salt that has the ability to form mineral precipitation with water-soluble salts.

[0013] The polymer includes polyvinyl alcohol, chitosan, gelatin and other soluble polymers rich in hydrogen bonds; the water-soluble salt includes calcium chloride, magnesium chloride, barium chloride, strontium chloride, ferric chloride, calcium sulfate, silver nitrate and other water-soluble salts that have the ability to form mineral precipitation with water-soluble salts;

[0014] Preferably, in S1, the mass concentration of the polymer in the precursor solution is 5% to 20%;

[0015] Preferably, in S1, the molar concentration of the water-soluble salt calcium chloride in the precursor solution is 0.034 mol / kg to 0.180 mol / kg.

[0016] Furthermore, in the method S2 for preparing a high-strength and tough hydrogel with a sandwich mineralized structure, the low-temperature freezing temperature is -5°C to -196°C, specifically -5°C, -10°C, -20°C, -30°C, -40°C, -50°C, -60°C, -70°C, -80°C, -90°C, -100°C, -110°C, -120°C, -130°C, -140°C, -150°C, -160°C, -170°C, -180°C, -190°C, -196°C, etc.

[0017] Furthermore, the freezing method is directional freezing; the cold field setting can be directional or non-directional, and the purpose of freezing is to pre-aggregate the molecular chains and create a pore structure.

[0018] The freezing chamber is a rectangular parallelepiped with a bottom length of 15mm, a bottom width of 0.5-4mm and a height of 15mm. A directional freezing temperature gradient is set on the side, with a cold source at the lower end of -80℃ guided by a steel plate and gradually increasing to the upper end.

[0019] Furthermore, in S3 of the method for preparing a high-strength and tough hydrogel with a sandwich mineralized structure, the induction solution is composed of one or more salt solutions, one or more components of which have a strong Hofmeister effect, and one or more components have the ability to precipitate one or more ions in the precursor.

[0020] Furthermore, the component having a significant Hofmeister effect is any one or a mixture of citrate, carbonate, sulfate, and potassium ions; the component having the ability to precipitate ions in the precursor solution is any one or a mixture of carbonate, sulfate, silver ions, and calcium ions.

[0021] In S3, the inducing component in the inducing solution is sodium carbonate, the phase separation driving component is sodium citrate, the total anion concentration is 0.25-2 mol / L, and the ratio of citrate to carbonate is (1.5-9):1.

[0022] Furthermore, in step S3, the induced soaking time is 12 to 48 hours.

[0023] The present invention also protects a high-strength and tough hydrogel having a sandwich mineralized structure that can be prepared by any of the above methods or any combination of steps.

[0024] The present invention also protects the use of the above-mentioned high-strength and tough hydrogel with a sandwich mineralized structure in shock-absorbing materials, vibration-absorbing materials, drug sustained-release materials, conductive materials, thermal conductive materials, energy storage materials, etc.

[0025] During the stretching process of the sandwich structure, the inherent difference in Poisson's ratio between the dense and porous layers causes stress concentration at the molecular chains' interfaces, gradually pulling them out. The uniform and continuous interlayer interface enhances energy dissipation. The in-situ mineralized mineral particles act like fiber clamps, securing the polymer fibers within the gel. Stress is transmitted and dissipated layer by layer between the mineral particles and the polymer, between the mineral particles, and within the mineral particles themselves, significantly reducing the likelihood of crack initiation and propagation. Furthermore, the highly entangled molecular chains gradually slip, untangle, and break, transferring tension between the chains, effectively dissipating elastic energy and thus improving the material's toughness.

[0026] This multi-level energy dissipation structure gives the hydrogel enhanced mechanical strength, high strain capacity and unprecedented tear resistance. This structure is a universal reinforcement method that can be used to prepare tough, crack-resistant hydrogels based on a series of minerals (such as calcium carbonate, calcium sulfate, magnesium carbonate, etc.) and polymers (such as polyvinyl alcohol, chitosan, etc.).

[0027] A high-strength, tear-resistant hydrogel with a sandwich mineralized structure can be used in typical impact resistance and buffering scenarios. It can efficiently absorb external stress and perform work while ensuring structural integrity.

[0028] The high-strength and tough hydrogel with a sandwich mineralized structure prepared by the present invention has a structure, thickness, and proportion of each layer of the hydrogel that changes with the preparation process, and the morphology and size of the mineralized particles that change with the preparation process.

[0029] The present invention prepares a high-strength and tough hydrogel with a sandwich mineralized structure into a fiber shape and fixes it between two cotton fiber bundles to obtain a simple tensile impact shock absorber. By monitoring the force oscillation changes caused by the free fall of a 500g weight, it was confirmed that the shock absorber with a composite SM-PVA fiber with a cross-sectional size of 0.8×1.2mm reduced the maximum impact force from 57.88N to only 19.50N, achieving efficient kinetic energy absorption while maintaining structural integrity and preventing cotton fiber breakage. Partial fiber breakage occurred in the cotton fiber bundle without the use of hydrogel. During the first maximum stress period, the shock absorber absorbed 1.76kJ of energy within 78ms. This shows that the hydrogel has excellent application potential in shock absorption, security components, and load-bearing structural materials.

[0030] Compared with the existing technology, the beneficial effects of the present invention are:

[0031] (1) In the design of tough hydrogel, the present invention constructs a unique sandwich mineralized structure hydrogel on a large scale of millimeter level. Through a simple method, the dense-porous-dense heterogeneous structure of the homogeneous matrix and the physical cross-linking structure of the mineralized center are realized, forming a multi-level structure from chain entanglement-chain crystallization-microscopic fiber bundles-macroscopic stratification, with high tensile strength (33.51MPa), high toughness (177.39MJ·m -3 ), high tear resistance (286.39kJ·m -2 ) and high stretchability (1026.55%), avoiding the problem of homogeneous, loose hydrogel networks breaking under stress. The tensile strength, toughness, and tear resistance far exceed those of most single-polymer hydrogels, dual / multi-network hydrogels, and nanocomposite hydrogels.

[0032] (2) This tough hydrogel has excellent recyclability, and its performance does not show significant decrease compared with the initial sample after two recycling cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 These are electron scanning microscopy and energy spectrum scanning images of the freeze-dried interlayer mineralized hydrogel in an embodiment of the present invention;

[0034] Figure 2 Graphs showing tensile test curves, pure shear test curves, and modulus, strength, toughness, and fracture energy test results of different hydrogels in the examples and comparative examples of the present invention;

[0035] Figure 3 1 is a comparison chart of strength test results of different hydrogels in the embodiments of the present invention;

[0036] Figure 4 Graph showing the results of a shock absorber and pure cotton thread buffering experiment in an embodiment of the present invention;

[0037] Figure 5 Graph showing the test results of strength, toughness, and fracture energy of different hydrogels in the embodiments of the present invention;

[0038] Figure 6 This is a graph showing the test results of the hydrogel recovery performance experiment in an embodiment of the present invention;

[0039] Figure 7 Graph showing the test results of the interlayer mineralized hydrogel modulus, strength, toughness, fracture energy, and elongation at break in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0041] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0042] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0043] In this application, all raw materials and reagents are commercially available products. In the following examples, the brand of PVA is 2099.

[0044] Example 1

[0045] 10g PVA and 0.5g CaCl2 were added to 89.5g deionized water and fully dissolved by heating in a 90℃ water bath and magnetic stirring. Subsequently, 50g PVA / CaCl2 solution was poured into a directional freezing mold, which consists of a long steel plate whose bottom is in contact with the cold source, and a solution directional freezing chamber located at the upper end of the steel plate and surrounded by a silicone strip and a polytetrafluoroethylene (PTFE) plate. The exposed steel plate portion at the bottom of the mold was immersed in a -80℃ ethanol bath. After the solution was completely frozen, it was taken out and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After soaking for 24h, a high-strength, tear-resistant hydrogel was obtained, which was recorded as SM-PVA-5%CaCl2.

[0046] Example 2

[0047] 10g PVA and 1g CaCl2 were added to 89g deionized water and fully dissolved by heating in a 90°C water bath and magnetic stirring. Subsequently, 50g PVA / CaCl2 solution was poured into the directional freezing mold in Example 1, and the exposed steel plate portion at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was taken out and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After soaking for 24h, a high-strength, tear-resistant hydrogel was obtained, which was recorded as SM-10% CaCl2PVA (referred to as SM-PVA in the figure).

[0048] Example 3

[0049] 10g of PVA and 2g of CaCl2 were added to 88g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA-20%CaCl2.

[0050] Example 4

[0051] 10g of PVA and 3g of CaCl2 were added to 87g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA-30%CaCl2.

[0052] Example 5

[0053] 10g of PVA and 1g of CaCl2 were added to 89g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1. The exposed steel plate at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of 2mol / L sodium citrate induction solution. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA / 0% Na2CO3.

[0054] Example 6

[0055] 10g of PVA and 1g of CaCl2 were added to 89g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.8mol / L sodium citrate and 0.2mol / L sodium carbonate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA / 10% Na2CO3.

[0056] Example 7

[0057] 10g of PVA and 1g of CaCl2 were added to 89g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.6mol / L sodium citrate and 0.4mol / L sodium carbonate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA / 20% Na2CO3.

[0058] Example 8

[0059] 10g of PVA and 1g of CaCl2 were added to 89g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.4mol / L sodium citrate and 0.6mol / L sodium carbonate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA / 30% Na2CO3.

[0060] Example 9

[0061] 10g of PVA and 1g of CaCl2 were added to 89g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.2mol / L sodium citrate and 0.8mol / L sodium carbonate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA / 40% Na2CO3.

[0062] Example 10

[0063] 10g of PVA and 1.43g of SrCl2 were added to 88.57g of deionized water and fully dissolved by heating in a 90°C water bath and magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After soaking for 24 hours, a highly tough, tear-resistant hydrogel was obtained, which was designated SM-PVA / SrCO3.

[0064] Example 11

[0065] 10g of PVA and 1.88g of BaCl2 were added to 88.12g of deionized water and fully dissolved by heating in a 90°C water bath and magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold of Example 1, and the exposed steel plate portion at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After soaking for 24 hours, a high-strength, tear-resistant hydrogel was obtained, which was recorded as SM-PVA / BaCO3.

[0066] Example 12

[0067] 10g of PVA and 0.86g of MgCl2 were added to 89.14g of deionized water and fully dissolved by heating in a 90°C water bath and magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold of Example 1, and the exposed steel plate portion at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After soaking for 24h, a high-strength, tear-resistant hydrogel was obtained, which was recorded as SM-PVA / MgCO3.

[0068] Example 13

[0069] 10g of PVA and 1g of CaCl2 were added to 89g of deionized water and thoroughly dissolved by heating in a 90°C water bath with magnetic stirring. Subsequently, 50g of the PVA / CaCl2 solution was poured into the directional freezing mold described in Example 1, and the exposed steel plate portion at the bottom of the mold was immersed in a -80°C ethanol bath. After the solution was completely frozen, it was removed and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium sulfate. After immersion for 24 hours, a highly tough, tear-resistant hydrogel was obtained, designated SM-PVA / CaSO4.

[0070] Comparative Example 1

[0071] 10g of PVA was added to 90g of deionized water and fully dissolved by heating in a 90°C waterbath with magnetic stirring. 50g of this solution was then directionally frozen in the mold of Example 1 at -80°C, removed, and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium carbonate. After immersion for 24 hours, comparative hydrogel 1 was obtained, designated FS-PVA.

[0072] Comparative Example 2

[0073] 10g of PVA was added to 90g of deionized water and thoroughly dissolved by heating in a 90°C waterbath with magnetic stirring. 50g of this solution was then directionally frozen in the mold described in Example 1 at -80°C, removed, and allowed to thaw naturally at room temperature. This material is labeled FT-PVA.

[0074] Comparative Example 3

[0075] 10g of PVA was added to 90g of deionized water and fully dissolved by heating in a 90°C water bath and magnetic stirring. 50g of this solution was then directionally frozen in the mold of Example 1 at -80°C, taken out and immersed in 500ml of a mixed induction solution of 1.5mol / L sodium citrate and 0.5mol / L sodium sulfate. After immersion for 24h, comparative hydrogel 3 was obtained, which was designated as FS-PVA / SO4. 2- .

[0076] Characterization results of the structure and properties of hydrogels under different parameters.

[0077] 1. The microstructure of the SM-PVA hydrogel prepared in Example 2 was characterized as follows: Figure 1 As shown by Figure 1 a It can be seen that the gel has a significant three-layer structure, in which the upper and lower layers have a denser structure, while the middle layer has a rich pore structure; Figure 1 b shows the distribution of micron-sized nanoparticles in the dense layer (i, ii) and porous layer (iii, iv) at a more microscopic scale, and displays the distribution of calcium elements through energy spectrum scanning.

[0078] 2. The SM-PVA hydrogel in Example 2 and the FS-PVA and FT-PVA hydrogels in the comparative example were subjected to tensile tests and pure shear tests. The test curves are shown in FIG. Figure 2 As shown in a and b, the test results show that SM-PVA hydrogel exhibits an ultra-high ultimate stress of 25.79 MPa and a high thermal conductivity of 120.98 MJ·m -3 The excellent toughness of SM-PVA is 807.49% and the modulus is 13.3Mpa. Compared with FS-PVA, the mechanical properties are fully enhanced. The strength of SM-PVA is 1611 times that of FT-PVA (0.016MPa), while the toughness is 3102 times that of FT-PVA (0.039MJ·m -3 ). In addition, SM-PVA showed 201.14 kJ·m -2 The excellent fracture energy of FT-PVA (0.32kJ·m -2 ) and FS-PVA (36.73 kJ·m -2 ) 628 times and 5 times ( Figure 2 c).

[0079] 3. The tensile test was carried out on the hydrogels prepared under different calcium chloride contents and different induction liquid ratios in the examples. The test results showed that as the content of Ca 2+ With the increase of concentration, the strength and toughness of the hydrogel first increase and then decrease. When the amount of calcium chloride added accounts for about 10wt% of the total mass of PVA, the strength of the gel reaches its peak. Figure 3 a. In addition, C6H5O7 in the induction solution 3- and CO3 2- The different ratios of also significantly affected the gel strength ( Figure 3 b) When the total concentration is 2M, the mechanical strength of the hydrogel increases with the increase of CO3 2- As the percentage increases, it first increases and then decreases, and the optimal enhancement ratio is 3:1.

[0080] 4. The potential application of this method in engineering scenarios was demonstrated by monitoring the time-dependent force oscillation caused by the free fall of a 500g weight. A simple shock absorber made of SM-PVA fiber with a cross-section of 0.8×1.2mm was successfully used to reduce the maximum impact force from 57.88N to only 19.50N ( Figure 4 c, d), while maintaining the integrity of the gel structure and preventing the breakage of cotton fibers, while some fibers broke in the cotton fiber bundles without hydrogel ( Figure 4 a, b).

[0081] 5. The mechanical properties of the hydrogels with different mineralized ion pairs in the examples were tested. Figure 5 As shown in a and b, compared with FS-PVA and FS-PVA / SO4 2- Compared with hydrogel, SM-PVA / SrCO3 (24.96MPa,

[0082] 115.50MJ·m -3 , 91.10 kJ·m -2 ), SM-PVA / BaCO3 (21.59MPa, 89.79MJ·m -3 、116.20kJ·m -2 ), SM-PVA / MgCO3 (21.45MPa, 99.95MJ·m -3 、158.20kJ·m -2 ), CaSO4 (24.53MPa, 118.50MJ·m -3 , 289.61 kJ·m -2 )The strength, toughness, and elongation at break of the hydrogels were significantly enhanced, indicating the versatility of this method.

[0083] 6. In addition, the various gels in the examples all showed excellent cycle performance and recyclability. The tensile test of the recycled SM-PVA hydrogel showed no decrease in mechanical properties after two recycling cycles, and the strength remained above 25 MPa ( Figure 6 ).

[0084] 7. When the PVA concentration is increased to 15wt%, the gel strength, toughness, fracture energy and elongation at break can be significantly increased to 33.51MPa, 177.39MJ·m -3 、286.39kJ·m -2 and 1026.55% ( Figure 7 ).

[0085] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

[0086] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of the description in this section that did not constitute prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A method for preparing a high-strength and tough hydrogel with a sandwich mineralized structure, characterized in that The following steps are involved: S1. preparing a water-soluble salt and a polymer into a uniform precursor aqueous solution; S2, freezing the precursor aqueous solution in S1 at low temperature to form a pre-gel precursor; S3. The pregel precursor of S2 is placed in an induction solution for structural induction to produce a sandwich mineralized structure, thereby obtaining a high-strength and tough hydrogel with a sandwich mineralized structure.

2. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 1, wherein: In S1, the water-soluble salt has the ability to produce mineral precipitation with anions or cations in the induction solution; wherein the total concentration of anions in the induction solution is 0.25 to 2 mol / L; and the polymer is a soluble polymer rich in hydrogen bonds.

3. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 1, wherein: In S2, the cryogenic freezing temperature is -5°C to -196°C.

4. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 1, wherein: In S3, the inducing solution is composed of one or more salt solutions, one or more components of which have a strong Hofmeister effect and serve as phase separation driving components; one or more components have the ability to precipitate one or more ions in the precursor and serve as inducing components.

5. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 2, wherein: The water-soluble salt is a water-soluble salt that has the ability to form mineral precipitation with water-soluble salts.

6. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 4, wherein: The component with a significant Hofmeister effect is any one or a mixture of several of citrate, carbonate, sulfate, and potassium ions; the component with the ability to precipitate ions in the precursor solution is any one or a mixture of several of carbonate, sulfate, silver ions, and calcium ions; the above-mentioned components with a significant Hofmeister effect and components with the ability to precipitate ions in the precursor solution cannot affect their presence in the induction solution in the form of ions.

7. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 1 or 2, characterized in that: In S1, the polymer is any one of polyvinyl alcohol, chitosan, and gelatin, or a mixture of several thereof; the water-soluble salt is any one of calcium chloride, magnesium chloride, barium chloride, strontium chloride, ferric chloride, calcium nitrate, silver nitrate, sodium carbonate, potassium carbonate, sodium sulfate, and a mixture of several thereof.

8. The method for preparing a high-strength and tough hydrogel having a sandwich mineralized structure according to claim 4 or 6, characterized in that: The inducing component in the inducing solution is sodium carbonate, the phase separation driving component is sodium citrate, the ratio of citrate to carbonate is 1.5-9:1, and the inducing soaking time is 12-48 hours.

9. A high-strength and tough hydrogel having a sandwich mineralized structure prepared by the method according to any one of claims 1 to 8.

10. Use of the high-strength and tough hydrogel with a sandwich mineralized structure as claimed in claim 9 in shock-absorbing materials, drug sustained-release materials, conductive materials, thermal conductive materials, and energy storage materials.

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