Triple-network hydrogel material and preparation method thereof

Abstract

The invention provides a triple network hydrogel material and a preparation method thereof, and belongs to the technical field of high-molecular compounds. The triple-network hydrogel material comprises a sodium alginate first-level network, a polyvinyl alcohol second-level network and a polyacrylamide third-level network. Wherein the sodium alginate primary network and the polyvinyl alcohol secondary network are connected through hydrogen-bond interaction, the polyacrylamide tertiary network is connected with the sodium alginate primary network and the polyvinyl alcohol secondary network through chain entanglement and hydrogen-bond interaction, and a uniform interpenetrating triple network structure is formed in the hydrogel. On the other hand, the invention also provides a preparation method of the triple network hydrogel material.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer compounds, and in particular, mainly relates to a triple network hydrogel material and a preparation method thereof. Background Art

[0002] Hydrogel is a three-dimensional network structure material formed by chemical or physical crosslinking of hydrophilic polymers. It has the characteristics of high water content, biocompatibility and environmental responsiveness. It has broad application prospects in biomedicine (such as tissue engineering scaffolds, drug sustained-release carriers), flexible electronic devices (such as sensors, wearable devices) and smart materials. In recent years, the development of hydrogels with both high mechanical properties and optical transparency has become an important research direction in the field of materials science. The core challenge lies in how to coordinate the contradictory relationship between mechanical enhancement mechanism and optical performance.

[0003] The current mainstream methods for improving the mechanical properties of hydrogels can be divided into four categories: salting-out induced phase transition, directional stretching orientation, multi-cycle freeze-thaw treatment and nanocomposite strategies. The salting-out method introduces a high concentration of salt solution (such as sodium sulfate, sodium citrate) to promote the desolvation of polymer chains to form a dense cross-linked network. However, when placed in a pure water environment, the diffusion of salt ions will cause the cross-linked network to dissociate, and the hydrogel prepared by the salting-out method is difficult to maintain stability under long-term hydration conditions. Mechanical stretching or repeated freeze-thaw can induce the orientation of polymer chains to form an anisotropic structure, but the microfibrillar structure formed by stretching will cause light scattering. The introduction of nanofillers such as nanoclay, cellulose nanocrystals (CNC) or graphene can significantly improve the modulus and fracture energy of hydrogels. However, high-content nanoparticles (e.g. >5wt%) are prone to agglomeration to form submicron clusters, which aggravate light loss and cause fluctuations in mechanical properties.

[0004] In summary, the synergistic optimization of the mechanical and optical properties of hydrogels has not yet been achieved in the relevant technologies of hydrogels. Therefore, it is of far-reaching practical significance to develop new preparation strategies and design hydrogels that have both high mechanical properties and high transparency. Summary of the invention

[0005] In view of this, in order to solve at least one technical problem in related technologies and other aspects, the present invention proposes a triple network hydrogel material, including: a primary network of sodium alginate, a secondary network of polyvinyl alcohol, and a tertiary network of polyacrylamide, wherein the primary network of sodium alginate and the secondary network of polyvinyl alcohol are connected by hydrogen bonding, and the tertiary network of polyacrylamide is connected with the primary network of sodium alginate and the secondary network of polyvinyl alcohol by chain entanglement and hydrogen bonding, forming a uniform interpenetrating triple network structure in the hydrogel.

[0006] According to an embodiment of the present invention, the visible light transmittance of the triple network hydrogel material is 45% to 90%.

[0007] According to an embodiment of the present invention, the elongation at break of the triple network hydrogel material is 600% to 1100%, the tensile strength of the triple network hydrogel material is 10 to 45 MPa, and the toughness of the triple network hydrogel material is 20 to 160 MJ / m 3 .

[0008] In another aspect of the present invention, a preparation method of the aforementioned triple network hydrogel material is also proposed, comprising: dropping a spreading solution comprising polyvinyl alcohol and sodium alginate onto a forming template, super-spreading the spreading solution to form a film, cross-linking the sodium alginate to form a primary network of sodium alginate, and obtaining a hydrogel precursor, wherein the forming template is a polyacrylamide hydrogel soaked in an ionic crosslinking agent; annealing the hydrogel precursor to produce crystalline domains of polyvinyl alcohol to form a secondary network of polyvinyl alcohol to obtain a dry gel; soaking the dry gel or the hydrogel formed after soaking the dry gel in water in an immersion solution comprising acrylamide monomers, and then irradiating the swollen hydrogel to polymerize the acrylamide monomers to form a tertiary network of polyacrylamide, and the tertiary network of polyacrylamide is connected with the primary network of sodium alginate and the secondary network of polyvinyl alcohol through chain entanglement to obtain a triple network hydrogel material.

[0009] According to an embodiment of the present invention, in the spreading solution, the mass ratio of polyvinyl alcohol to sodium alginate is 16:1-4:1.

[0010] According to an embodiment of the present invention, the ionic cross-linking agent includes any one of a soluble calcium ion solution and a soluble aluminum ion solution.

[0011] According to an embodiment of the present invention, in the annealing process, the annealing temperature is 90-110° C., and the annealing time is 60-100 min.

[0012] According to an embodiment of the present invention, the soaking liquid further includes a photoinitiator and deionized water, and the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0013] According to an embodiment of the present invention, in the soaking liquid, the mass concentration of acrylamide monomer is 40wt%~70wt%.

[0014] According to an embodiment of the present invention, the wavelength of the illumination is 365 nm, and the illumination time is 30 s to 2 min.

[0015] According to the embodiments of the present invention, the triple network hydrogel proposed in the present invention forms a triple uniform interpenetrating hydrogel network through the three-level network structure design of "sodium alginate-polyvinyl alcohol-polyacrylamide". The triple network hydrogel integrates (intramolecular and intermolecular) hydrogen bonds, (sodium alginate primary network) ionic crosslinking, (polyvinyl alcohol secondary network) crystal domain enhancement and (polyacrylamide tertiary network) chain entanglement mechanism, so that the material has high strength and toughness, high transparency and excellent underwater stability at the same time, and realizes the coordinated optimization of mechanical enhancement mechanism and optical properties at the molecular scale, breaking through the technical bottleneck that traditional hydrogels are difficult to achieve both strength and toughness and transparency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the microstructure of the triple network hydrogel material prepared in an embodiment of the present invention;

[0017] Figure 2 is a cross-sectional electron micrograph of the hydrogel 5 prepared in an embodiment of the present invention;

[0018] Figure 3 is a cross-sectional energy dispersive X-ray spectrum of the hydrogel 5 prepared in an embodiment of the present invention, wherein a is an energy dispersive X-ray spectrum of carbon element, b is an energy dispersive X-ray spectrum of oxygen element, c is an energy dispersive X-ray spectrum of nitrogen element, and d is an energy dispersive X-ray spectrum of calcium element;

[0019] Figure 4 is a comparison diagram of tensile stress-strain curves of hydrogels 2-5 prepared in the examples of the present invention;

[0020] Figure 5 is a transparency test chart of the hydrogel 5 prepared in an embodiment of the present invention;

[0021] Figure 6 is a test diagram of the antifouling performance of the hydrogel 5 prepared in an embodiment of the present invention;

[0022] Figure 7 1 is a test chart of the anti-fog performance of the hydrogel 5 prepared in the embodiment of the present invention, wherein a is a test chart of the lens before being treated with high-temperature water vapor, and b is a test chart of the lens after being treated with high-temperature water vapor;

[0023] Figure 8 1 is a test diagram of the anti-friction performance of hydrogel 1 and hydrogel 5 prepared in the embodiment of the present invention, wherein a is the result diagram of hydrogel 1 after testing for 1 hour, and b is the test diagram of hydrogel 5 after testing for 7 hours;

[0024] Fig. 9This is a test chart of the visible light transmittance of the hydrogel 5 prepared in the embodiment of the present invention under water and in the air. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0026] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0028] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. If the full text involves descriptions such as "first", "second", etc., the descriptions such as "first", "second", etc. are only used to distinguish similar objects, and cannot be understood as indicating or implying their relative importance, order of precedence, or implicitly indicating the number of technical features indicated. It should be understood that the data described by "first", "second", etc. can be interchangeable under appropriate circumstances.

[0030] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] The purpose of the present invention is to provide a hydrogel with high toughness and high transparency and a preparation method thereof. Through the strategy of "super spreading-annealing-in situ polymerization", a variety of effective strengthening and toughening mechanisms are gradually introduced, such as ionic cross-linking, crystallization domain, and chain entanglement, to improve the mechanical properties of the hydrogel. At the same time, the constructed multilayer network is uniform and dense, giving the hydrogel high transparency and high underwater mechanical properties.

[0032] Figure 1 It is a schematic diagram of the microstructure of the triple network hydrogel material prepared in an embodiment of the present invention.

[0033] The present invention proposes a triple network hydrogel material, such as Figure 1 As shown, it includes: sodium alginate (SA) primary network, polyvinyl alcohol (PVA) secondary network, and polyacrylamide (PAAm) tertiary network. Among them, the sodium alginate primary network and the polyvinyl alcohol secondary network are connected by hydrogen bonding, and the polyacrylamide tertiary network is connected with the sodium alginate primary network and the polyvinyl alcohol secondary network through chain entanglement and hydrogen bonding, forming a uniform interpenetrating triple network structure in the hydrogel.

[0034] According to the embodiments of the present invention, the triple network hydrogel proposed in the present invention forms a triple uniform interpenetrating hydrogel network through the three-level network structure design of "sodium alginate-polyvinyl alcohol-polyacrylamide". The triple network hydrogel integrates (intramolecular and intermolecular) hydrogen bonds, (sodium alginate primary network) ionic crosslinking, (polyvinyl alcohol secondary network) crystal domain enhancement and (polyacrylamide tertiary network) chain entanglement mechanism, so that the material has high strength and toughness, high transparency and excellent underwater stability at the same time, and realizes the coordinated optimization of mechanical enhancement mechanism and optical properties at the molecular scale, breaking through the technical bottleneck that traditional hydrogels are difficult to achieve both strength and toughness and transparency.

[0035] Specifically, the primary alginate network is based on dynamic ionic crosslinks (e.g., Ca 2+Coordination), when subjected to stress, it preferentially dissipates energy through reversible bond breaking, which can delay crack initiation; the secondary network of polyvinyl alcohol provides rigid support through a physical cross-linked network connected by hydrogen bonds, and its nanocrystalline domains break during deformation as "sacrificial bonds", which can further absorb energy; the long chain entanglement of the tertiary network of polyacrylamide forms a topological interpenetrating structure, which disperses stress through slip reconstruction during macroscopic stretching, which is beneficial to prevent crack propagation. At the same time, the strong hydrogen bonding between hydroxyl and carboxyl groups between the various levels of networks enhances the stress transfer efficiency between the two networks and reduces the performance loss caused by interface slip; the tertiary network of polyacrylamide also penetrates the primary network of sodium alginate and the secondary network of polyvinyl alcohol through physical entanglement to form a "molecular anchor point", which realizes energy redistribution through chain segment slip and reorganization during deformation, avoiding the brittleness caused by chemical cross-linking. The hierarchical response mechanism of the triple network enables the hydrogel material to have both high toughness and high strength, breaking through the performance limit of a single network or a double network. Furthermore, the uniform distribution of ionic crosslinking points and hydrogen bond crosslinking points and the reasonable setting of crystallization domains avoid various types of optical scattering, and the absence of external fillers also avoids the introduction of colored or opaque substances to reduce transparency.

[0036] In some specific embodiments, the triple network hydrogel material proposed in the present invention has no nanofillers or chemical crosslinking agent residues, can be used as an all-natural / bionic polymer composition, and is suitable for implantable medical devices; its high underwater transparency and anti-swelling properties meet the stringent requirements of deep-sea flexible electronics and underwater optical devices; the open structure of the three-level network also allows the introduction of functional monomers (such as thermosensitive NIPAM, conductive polyaniline), and expands to the fields of intelligent sensing and driving. Compared with the existing high mechanical properties hydrogel, the hydrogel material prepared by the present invention also has higher transparency, thereby broadening the application range of the hydrogel. The hydrogel material prepared by the present invention can be adhered to materials such as glass plates and swimming goggles to achieve anti-fouling and anti-fogging protection, and has broad application prospects in the fields of underwater detectors.

[0037] In some specific embodiments, the thickness of the triple network hydrogel material is 30-40 μm, and the mass ratio of the primary network, the secondary network, and the tertiary network is 16:1:5-16:1:15. The thinner triple network hydrogel material ensures sufficient dispersion of the ionic crosslinker and the acrylamide monomer.

[0038] According to an embodiment of the present invention, the visible light transmittance of the triple network hydrogel material is 45% to 90%.

[0039] According to an embodiment of the present invention, the present invention proposes a triple network hydrogel material that has excellent visible light transparency and good ultraviolet transmittance, especially in an underwater environment. The regulation of ultraviolet transmittance can adapt to scene requirements such as phototherapy, ultraviolet shielding or photocatalysis.

[0040] According to the embodiment of the present invention, the elongation at break of the triple network hydrogel is 600%~1100%, the tensile strength of the triple network hydrogel is 10~45MPa, and the toughness of the triple network hydrogel is 20~160MJ / m 3 .

[0041] In another aspect of the present invention, a preparation method of the aforementioned triple network hydrogel material is also proposed, comprising: dropping a spreading solution comprising polyvinyl alcohol and sodium alginate onto a forming template, super-spreading the spreading solution to form a film, cross-linking the sodium alginate to form a primary network of sodium alginate, and obtaining a hydrogel precursor, wherein the forming template is a polyacrylamide hydrogel soaked in an ionic crosslinking agent; annealing the hydrogel precursor to produce crystalline domains of polyvinyl alcohol to form a secondary network of polyvinyl alcohol to obtain a dry gel; soaking the dry gel or the hydrogel formed after soaking the dry gel in water in an immersion solution comprising acrylamide monomers, and then irradiating the swollen hydrogel to polymerize the acrylamide monomers to form a tertiary network of polyacrylamide, and the tertiary network of polyacrylamide is connected with the primary network of sodium alginate and the secondary network of polyvinyl alcohol through chain entanglement to obtain a triple network hydrogel material.

[0042] According to the embodiment of the present invention, the preparation method realizes the uniform construction and performance synergy of the triple network at the molecular scale through the three-step process of "template-guided super spreading-controlled annealing-in situ photopolymerization". Specifically, firstly, the pre-cross-linked polyacrylamide hydrogel is used as a template, and its surface hydrophilicity and microporous structure are used to guide the uniform extension of the spreading solution, combined with the slow release of Ca in the template. 2+ The ionic crosslinking points are evenly distributed; the hydrogel precursor is then annealed to precisely control the mobility of the PVA molecular chain, inducing the formation of a secondary polyvinyl alcohol network with a nanoscale crystal domain mechanism; finally, the dry gel (or its hydrogel) is immersed in an acrylamide monomer solution, and its swelling effect is used to allow the acrylamide monomer molecules to fully penetrate into the double network pores, followed by photoinitiated in-situ polymerization. The tertiary network formed by the long chain of polyacrylamide forms an interpenetrating structure of chain entanglement through physical entanglement with the primary network of sodium alginate and the secondary network of polyvinyl alcohol, significantly improving the fracture energy, and the entanglement does not introduce chemical crosslinking agents, maintaining the consistency of the optical refractive index.

[0043] Specifically, the elastic modulus of the polyacrylamide template matches the surface tension of the spreading solution, suppressing wrinkles or ruptures during the film-forming process and ensuring the integrity of the primary network structure. The use of the molding template helps to accurately control the structure of the triple network hydrogel material. The pre-formed structure of the polyacrylamide template is conducive to guiding the spreading of the primary network of sodium alginate to form a more uniform film. Pre-immersion of the ionic crosslinker can ensure the uniformity of the crosslinking of sodium alginate, avoid local over-crosslinking or under-crosslinking, and thus improve the overall performance. At the same time, the ionic crosslinking is limited to the primary network, and the dense structure of the triple network suppresses the loss of ions in a pure water environment.

[0044] In some specific embodiments, the method for preparing the molding template includes preparing a polyacrylamide hydrogel for auxiliary molding, placing the polyacrylamide hydrogel in water to swell to saturation, and placing the swelled auxiliary molding hydrogel in a solution that is immiscible with the hydrogel.

[0045] According to an embodiment of the present invention, in the spreading solution, the mass ratio of polyvinyl alcohol to sodium alginate is 16:1-4:1.

[0046] According to an embodiment of the present invention, a higher PVA ratio is beneficial to enhancing the flexibility and ductility of the triple network hydrogel material while reducing brittleness, and is suitable for scenarios that require repeated deformation (such as flexible sensors). A higher sodium alginate ratio can increase the crosslinking density and rigidity of the triple network hydrogel material, which is suitable for load-bearing biological scaffolds. The hydroxyl group of PVA and the carboxyl group of sodium alginate can form hydrogen bonds, inhibit phase separation, and improve light transmittance. This ratio range takes into account mechanical strength, swelling stability, and processing feasibility by finely regulating the synergistic effect of the two phases.

[0047] According to an embodiment of the present invention, the ionic cross-linking agent includes any one of a soluble calcium ion solution and a soluble aluminum ion solution.

[0048] According to an embodiment of the present invention, in the annealing process, the annealing temperature is 90-110° C., for example, 90° C., 100° C., 110° C., etc., and the annealing time is 60-100 min.

[0049] According to an embodiment of the present invention, the annealing temperature is close to the glass transition temperature of PVA (50~85°C), which ensures moderate movement of the molecular chains, induces the formation of nanoscale crystalline domains, avoids the formation of excessive crystals in the secondary network of polyvinyl alcohol and causes light scattering, and the crystallinity increases with the annealing time, which is beneficial to improving the modulus while avoiding brittleness caused by excessive crystallization.

[0050] According to an embodiment of the present invention, the soaking liquid further includes a photoinitiator and deionized water, and the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0051] According to an embodiment of the present invention, in the soaking liquid, the mass concentration of acrylamide monomer is 40wt%~70wt%.

[0052] According to an embodiment of the present invention, a higher concentration of acrylamide monomer can significantly improve the monomer penetration efficiency, shorten the swelling time, ensure that the tertiary network of polyacrylamide fully penetrates the primary network of sodium alginate and the secondary network of polyvinyl alcohol, and enhances the interfacial bonding force. A lower concentration can avoid network damage caused by excessive swelling and maintain structural stability. This concentration range achieves synergistic optimization of mechanical and optical properties by balancing swelling, polymerization and structural stability, providing key parameter support for the efficient preparation of triple network hydrogels.

[0053] According to an embodiment of the present invention, the wavelength of the illumination is 365 nm, and the illumination time is 30 s to 2 min.

[0054] According to an embodiment of the present invention, photopolymerization is completed at room temperature, avoiding high temperature-induced melting of the crystalline domains of the PVA secondary network or degradation of the sodium alginate primary network, thereby ensuring the stability of the triple network.

[0055] It should be noted that the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0056] Example 1

[0057] 15g acrylamide monomer, 0.3g N,N-methylenebisacrylamide (MBAAm) cross-linker and 0.3g ammonium persulfate (APS) initiator were dissolved in 100mL deionized water (DI), 300μL N,N,N',N'-tetramethylethylenediamine (TEMED) catalyst was added and stirred quickly and evenly, and the mixed solution was poured into a mold and placed at room temperature for 5min to gel. Then the gel was demolded and placed in deionized water to fully swell and remove the unreacted monomer to prepare polyacrylamide hydrogel as a molding template.

[0058] The molded substrate was cut into a size of 10 cm × 10 cm, and then immersed in a 1M calcium chloride solution (CaCl2) to fully absorb the CaCl2 solution.

[0059] 16g of polyvinyl alcohol (PVA) solid particles were added to 500mL of deionized water, heated and stirred at 110ºC for 6h to obtain a 4wt% PVA solution; 2g of sodium alginate (SA) powder was added to 100mL of deionized water, stirred at room temperature for 12h to obtain a 2wt% SA solution. 4wt% PVA solution, 2wt% SA solution and deionized water were mixed in a volume ratio of 8:1:4, and ultrasonicated for 5min to remove bubbles to obtain a spreading solution (referred to as PVA / SA reaction solution).

[0060] The spreading solution was continuously added dropwise to the Ca 2+ The spreading solution is super-spread on the surface of the forming template, and reacts rapidly at the interface to form a film, forming a primary network of sodium alginate to obtain a hydrogel precursor. After the reaction is completed, the formed hydrogel precursor is transferred to polytetrafluoroethylene (PTFE) and dried at room temperature. After sufficient drying, the PTFE membrane carrying the dried hydrogel precursor is immersed in deionized water for 30 minutes, and then annealed in a 100ºC oven for 90 minutes to form a polyvinyl alcohol secondary network to obtain a dry gel (recorded as PVA / CA dry gel). After annealing, the dry gel is peeled off the PTFE membrane and fully immersed in deionized water to obtain a PVA / CA hydrogel (recorded as hydrogel 1).

[0061] At room temperature, 104g of acrylamide monomer and 0.4g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (I2959) photoinitiator were dissolved in 150g, 100g, 80g and 64g of deionized water, respectively, to obtain acrylamide (AAm) monomer solutions of different concentrations as soaking solutions (respectively recorded as soaking solution 1, soaking solution 2, soaking solution 3, soaking solution 4). PVA / CA hydrogel was soaked in the above soaking solutions of different concentrations to fully swell. After swelling equilibrium, the hydrogel was taken out and the excess monomer solution on the surface of the gel was removed. The hydrogel was exposed to a 365nm wavelength ultraviolet lamp for 1min, and the acrylamide monomer was induced by ultraviolet light to undergo free radical polymerization to form a polyacrylamide tertiary network, thereby obtaining a triple network hydrogel material.

[0062] After the illumination, the triple network hydrogel material was immersed in deionized water to remove the unreacted monomers and fully swell to obtain a series of PVA / CA / PAAm-W hydrogels with different polyacrylamide contents, where W represents the molar ratio of acrylamide monomer to deionized water in the immersion solution.

[0063] The morphology and performance of the hydrogel materials prepared in Example 1 were tested. Among them, the PVA / CA hydrogel without soaking in the soaking solution was recorded as hydrogel 1, and the triple network hydrogel materials prepared by soaking in soaking solutions with different acrylamide monomer concentrations were recorded as hydrogel 2 (W=0.18), hydrogel 3 (W=0.26), hydrogel 4 (W=0.33), and hydrogel 5 (W=0.41). Specifically, the composition of the soaking solution in hydrogels 1-5 is shown in Table 1.

[0064] Table 1

[0065]

[0066] The microscopic morphology of hydrogel 5 was observed.

[0067] Figure 2 is a cross-sectional electron micrograph of the hydrogel 5 prepared in an embodiment of the present invention; Figure 3 is an energy dispersive X-ray spectrum (EDS) of a cross section of the hydrogel 5 prepared in an embodiment of the present invention, wherein a is an energy dispersive X-ray spectrum of the carbon (C) element, b is an energy dispersive X-ray spectrum of the oxygen (O) element, c is an energy dispersive X-ray spectrum of the nitrogen (N) element, and d is an energy dispersive X-ray spectrum of the calcium (Ca) element.

[0068] like Figure 2 As shown in the figure, the three networks are evenly distributed in the hydrogel without obvious phase separation or agglomeration, which indicates that during the preparation process, the various network components were fully mixed and cross-linked to form a uniform triple network structure.

[0069] like Figure 3 a in Figure 3 b in Figure 3 c in Figure 3 As shown in d, the carbon and nitrogen elements in hydrogel 5 come from the raw materials of hydrogel 5, such as sodium alginate and other organic components. Oxygen is a common element in hydrogels and comes from hydroxyl groups and other oxygen-containing functional groups. Calcium can exist in the hydrogel as an ion or in the form of combination with other compounds. Different elements are evenly distributed without obvious agglomeration, which proves the uniformity of the triple network.

[0070] The mechanical properties of the hydrogel prepared in Example 1 were tested, and the specific results are recorded in Table 2 below.

[0071] Table 2

[0072]

[0073] Figure 43 is a comparison diagram of the tensile stress-strain curves of the hydrogels 2-5 prepared in the examples of the present invention.

[0074] As shown in Table 2 and Figure 4 As shown, the hydrogel material prepared by the present invention has good mechanical properties. As the concentration of acrylamide monomer in the immersion solution increases, the mechanical properties of the hydrogel material are significantly improved, which is significantly better than the hydrogel 1 with a double network structure.

[0075] The covering power performance of the hydrogel prepared in Example 1 was tested.

[0076] Figure 5 This is a transparency test chart of the hydrogel 5 prepared in the embodiment of the present invention.

[0077] like Figure 5 As shown, when the triple network hydrogel prepared by the present invention is covered on a colored flower, the color and shape of the flower can be clearly seen, and there is almost no fuzzy area, which reflects the extremely high transparency of the triple network hydrogel.

[0078] The hydrogel prepared in Example 1 was attached to one end of a glass sheet and placed in water containing oil, and the antifouling performance of the hydrogel prepared in Example 1 was tested.

[0079] Figure 6 This is a test chart of the antifouling performance of the hydrogel 5 prepared in the embodiment of the present invention.

[0080] like Figure 6 As shown, it can be observed that there is almost no residual oil on the glass sheet with hydrogel 5 attached, while in contrast, a large amount of oil is stained on the glass sheet without hydrogel attached. This shows that the triple network hydrogel material proposed in the present invention has an anti-fouling function.

[0081] The hydrogel prepared in Example 1 was attached to the inner side of one lens of the swimming goggles and placed on the upper end of hot water vapor, and the anti-fogging performance of the hydrogel prepared in Example 1 was tested.

[0082] Figure 7 3 is a test chart of the anti-fog performance of the hydrogel 5 prepared in the embodiment of the present invention, wherein a is a test chart of the lens before being treated with high-temperature water vapor, and b is a test chart of the lens after being treated with high-temperature water vapor.

[0083] like Figure 7 a and Figure 7As shown in b, the lens with hydrogel attached remains transparent, and the object behind can be clearly observed through the lens. In contrast, the lens without hydrogel attached produces water mist on the surface, and the object behind the lens cannot be clearly observed. This shows that the triple network hydrogel material proposed in the present invention has an anti-fog function.

[0084] The hydrogel prepared in Example 1 was subjected to a friction test.

[0085] Figure 8 3 are test diagrams of the anti-friction performance of hydrogel 1 and hydrogel 5 prepared in the embodiments of the present invention, wherein a is the result diagram of hydrogel 1 after testing for 1 hour, and b is the test diagram of hydrogel 5 after testing for 7 hours.

[0086] like Figure 8 a and Figure 8 As shown in b, hydrogel 5 remains intact after 7 hours of friction, while hydrogel 1 is damaged after 1 hour of friction. This shows that the triple network hydrogel material proposed in the present invention has an anti-friction protective function.

[0087] The hydrogel prepared in Example 1 was tested for light transmittance.

[0088] Fig. 9 This is a light transmittance test chart of the hydrogel 5 prepared in the embodiment of the present invention.

[0089] like Fig. 9 As shown, the visible light transmittance of the hydrogel 5 in the air is 45%-60%, and the visible light transmittance underwater can reach 80%-90%, which has excellent visible light transmittance performance.

[0090] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A triple network hydrogel material, characterized in that: The triple network hydrogel material comprises: a primary network of sodium alginate, a secondary network of polyvinyl alcohol, and a tertiary network of polyacrylamide; The primary network of sodium alginate and the secondary network of polyvinyl alcohol are connected by hydrogen bonding, and the tertiary network of polyacrylamide is connected with the primary network of sodium alginate and the secondary network of polyvinyl alcohol by chain entanglement and hydrogen bonding, forming a uniform interpenetrating triple network structure in the hydrogel.

2. The triple network hydrogel material according to claim 1, characterized in that: The visible light transmittance of the triple network hydrogel material is 45% to 90%.

3. The triple network hydrogel material according to claim 1, characterized in that: The elongation at break of the triple network hydrogel material is 600% to 1100%, the tensile strength of the triple network hydrogel material is 10 to 45 MPa, and the toughness of the triple network hydrogel material is 20 to 160 MJ / m 3 .

4. A method for preparing a triple network hydrogel material according to any one of claims 1 to 3, characterized in that: The preparation method comprises: A spreading solution containing polyvinyl alcohol and sodium alginate is dripped onto a forming template, the spreading solution is super-spread to form a film, and the sodium alginate is cross-linked to form a primary network of sodium alginate to obtain a hydrogel precursor, wherein the forming template is a polyacrylamide hydrogel soaked in an ionic cross-linking agent; Annealing the hydrogel precursor to generate crystalline domains in the polyvinyl alcohol and form a polyvinyl alcohol secondary network to obtain a dry gel; The dry gel or the hydrogel formed after the dry gel is immersed in water is immersed in an immersion solution containing acrylamide monomers, and then the swollen hydrogel is irradiated with light to polymerize the acrylamide monomers to form a polyacrylamide tertiary network. The polyacrylamide tertiary network is connected with the sodium alginate primary network and the polyvinyl alcohol secondary network through chain entanglement to obtain a triple network hydrogel material.

5. The preparation method according to claim 4, characterized in that: In the spreading solution, the mass ratio of the polyvinyl alcohol to the sodium alginate is 16:1 to 4:

1.

6. The preparation method according to claim 4, characterized in that: The ionic crosslinking agent includes any one of a soluble calcium ion solution and a soluble aluminum ion solution.

7. The preparation method according to claim 4, characterized in that: In the annealing treatment, the annealing temperature is 90-110° C. and the annealing time is 60-100 min.

8. The preparation method according to claim 4, characterized in that: The soaking liquid also includes a photoinitiator and deionized water, and the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

9. The preparation method according to claim 8, characterized in that: In the soaking liquid, the mass concentration of the acrylamide monomer is 40wt%~70wt%.

10. The preparation method according to claim 4, characterized in that: The wavelength of the illumination is 365 nm, and the duration of the illumination is 30 s to 2 min.

Images