Organic-inorganic hybrid starch composite hydrogel and preparation method thereof
By phosphorylation of starch and hybrid crosslinking with inorganic salts and antifreeze agents, a starch composite hydrogel with excellent stretching, conductivity, water retention and freezing resistance was prepared, which solved the performance problems of existing starch hydrogels at extreme temperatures and broadened its application areas.
Patent Information
- Application Number
- CN202510383409.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-28
- Publication Date
- 2025-06-10
AI Technical Summary
Existing starch hydrogel materials are prone to freeze under low temperature conditions and easily evaporate and lose water under high temperature conditions, resulting in a degradation of performance and limiting their application range.
By phosphorylation of starch with phosphate and hybrid crosslinking with inorganic salts and antifreeze, an organic-inorganic hybrid starch composite hydrogel with excellent tensile properties, conductivity, water retention and freeze resistance were prepared.
It has achieved high tensile, conductive stress stimulation response and good water retention and freezing resistance under high and low temperature environments, making it suitable for wearable materials.
Smart Images
Figure CN120118341A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of natural polymer functional materials, and particularly relates to an organic-inorganic hybrid starch composite hydrogel with high tensile, conductive, water-retaining, and antifreeze properties and a preparation method thereof. Background Art
[0002] With the development of science and technology, portable and lightweight flexible electronic devices show great application potential in the fields of human motion detection, medical monitoring, human-computer interaction, etc. Therefore, the research on electronic skin materials has attracted great interest. Flexible wearable sensors can simulate various deformations of the human skin and convert external stimuli into detectable electronic signals. Hydrogel is a commonly used material for wearable sensors. It is a water-containing material with a three-dimensional network structure and has characteristics such as good biocompatibility, self-healing property, adhesiveness, and good mechanical properties. However, due to the special water-retaining property of the hydrogel, such materials can only be used in specific environments. When the temperature is too high or too low, the water in the gel will volatilize or freeze and solidify, losing properties such as stress sensing.
[0003] As a renewable and widely sourced natural polymer material, starch has the characteristics of being green, environmentally friendly, safe, non-toxic, and biodegradable, and is widely used. However, starch hydrogels have poor tensile properties, conductivity, and mechanical properties, and there is also a problem that the water in the hydrogel is easily volatilized or frozen at high or low temperatures, which limits its scope of use. Summary of the Invention
[0004] Aiming at the deficiencies of the existing starch hydrogel materials, such as poor tensile and conductive properties, easy freezing under low-temperature conditions, and easy evaporation of water and becoming brittle under high-temperature conditions, the present invention provides an organic-inorganic hybrid starch composite hydrogel and a preparation method thereof. By compounding an organic polymer material with an inorganic material, the preparation of a starch-based composite hydrogel with excellent tensile properties, conductivity, good water retention, and antifreeze properties is realized.
[0005] To achieve the above object, the present invention adopts the following technical solutions: An organic-inorganic hybrid starch composite hydrogel, and its preparation method includes the following steps: (1) Starch phosphorylation: Add starch to water, and add phosphate. After mixing evenly, react to obtain phosphorylated starch; (2) Preparation of an organic-inorganic hybrid cross-linking agent: Add an inorganic salt to an aqueous solution of polyvinyl alcohol to obtain a transparent organic-inorganic hybrid cross-linking agent; (3)Preparation of starch hydrogel: Add the organic-inorganic hybrid crosslinking agent obtained in step (2) to the phosphorylated starch obtained in step (1), and add an aqueous borax solution. Mix well to allow the phosphorylated starch and the crosslinking agent to fully self-crosslink, obtaining an organic-inorganic hybrid starch-based colloid; (4)Antifreeze modification: Add an antifreeze to the starch-based colloid obtained in step (3), and obtain a composite starch-based colloid through physical action; (5)Fermentation of starch hydrogel: Uniformly add yeast to the composite starch-based colloid obtained in step (4). After physical action and fermentation, a starch composite hydrogel with a three-dimensional network structure is obtained.
[0006] Further, the starch described in step (1) includes one or more of corn starch, potato starch, legume starch, wheat starch, etc.
[0007] Further, the phosphate described in step (1) includes one or more of orthophosphate, pyrophosphate, metaphosphate, tripolyphosphate, etc., and its addition amount is 0.1-10% of the absolute dry mass of the starch.
[0008] Further, the temperature of the reaction described in step (1) is 80-155 °C, and the time is 1-10 h.
[0009] Further, the mass concentration of the phosphorylated starch obtained in step (1) is 20-80%.
[0010] Further, the mass concentration of the aqueous polyvinyl alcohol solution described in step (2) is 1-20%, and the polyvinyl alcohol raw materials used include granular, flaky, and flocculent forms.
[0011] Further, the inorganic salts described in step (2) include one or more of calcium chloride, magnesium chloride, iron chloride, zinc chloride, etc., and their addition amount is 50-200% of the mass of the polyvinyl alcohol used.
[0012] Further, the dosage of the organic-inorganic hybrid crosslinking agent and the phosphorylated starch in step (3) is converted according to the ratio of the absolute dry mass of the starch to the mass of the polyvinyl alcohol being 4:1.
[0013] Further, the mass concentration of the aqueous borax solution described in step (3) is 1-10%, and its addition amount is 1-10% of the sum of the absolute dry mass of the starch and the mass of the polyvinyl alcohol used.
[0014] Further, the mixing time in step (3) is 0.5-5 h.
[0015] Further, the antifreeze described in step (4) includes one or more of ethylene glycol, glycerol, isopropyl alcohol, etc., and its addition amount is 1-50% of the sum of the absolute dry mass of the starch and the mass of the polyvinyl alcohol used.
[0016] Further, the addition amount of yeast in step (5) is 1-5% of the sum of the absolute dry mass of the used starch and the mass of polyvinyl alcohol.
[0017] Further, the temperature of the fermentation described in step (5) is 10-50°C, and the time is 0.5-48 h.
[0018] Further, the physical actions described in steps (4) and (5) include one or more of physical stirring, kneading, beating, etc., and the action time is 10-60 min.
[0019] Compared with the existing antifreeze hydrogels, the advantages of the present invention are as follows: (1) The synthesis method of the present invention is simple, environmentally friendly, easy to repeat and mass-produce, and is suitable for industrialization; (2) The starch composite hydrogel prepared by the present invention has good tensile properties, electrical conductivity, adhesiveness and self-healing properties through organic and inorganic hybridization, which can broaden its application fields; (3) The present invention uses natural starch as the main raw material, and constructs a starch composite hydrogel with a uniform three-dimensional porous structure through chemical cross-linking and biological fermentation methods. It has high tensile and electrically conductive stress stimuli responses at high and low temperature environments, as well as good water retention and antifreeze properties, etc., showing its application potential in the field of wearable materials. Description of the Drawings
[0020] Figure 1 It is a macroscopic photograph of the starch composite hydrogel prepared in Example 1. As can be seen from the figure, the obtained hydrogel has good plasticity.
[0021] Figure 2 It is a tensile diagram of the starch composite hydrogel prepared in Example 1. As can be seen from the figure, the obtained hydrogel has excellent tensile properties, and the elongation at break can reach 6000%.
[0022] Figure 3 It is a comparison diagram of the mechanical properties of the starch composite hydrogel prepared in Example 1 and the pure starch hydrogel prepared in Comparative Example 1. As can be seen from the figure, compared with the pure starch hydrogel, the tensile strain and stress of the starch composite hydrogel have been effectively improved, and the mechanical properties are significantly improved.
[0023] Figure 4 It is an adhesiveness test diagram of the starch composite hydrogel prepared in Example 1. As can be seen from the figure, the starch composite hydrogel has good adhesiveness and can adhere to the surfaces of different materials (metal, pigskin, glass, wood, plastic and rubber).
[0024] Figure 5Electron micrographs of the pure starch hydrogel (a) prepared in Comparative Example 1, the starch composite hydrogel (b) prepared without fermentation in Comparative Example 5, and the starch composite hydrogel (c) prepared in Example 1. It can be seen from the figure that the pure starch hydrogel does not have a porous structure, the starch composite hydrogel prepared by adding a cross-linking agent without fermentation has a certain reticular structure, while the starch composite hydrogel prepared in the example has an obvious three-dimensional reticular structure.
[0025] Figure 6 Water retention test chart of the starch composite hydrogel prepared in Example 1. It can be seen from the figure that the starch composite hydrogel has good water retention. After being placed at 80 °C for 7 days, its water retention rate can still reach 100%. Specific implementation mode
[0026] An organic-inorganic hybrid starch composite hydrogel, and its preparation method includes the following steps: (1) Starch phosphorylation: Add starch to water, and add phosphates accounting for 0.1-10% of the absolute dry mass of the starch. After mixing evenly, react at 80-155 °C for 1-10 h to obtain phosphorylated starch with a mass concentration of 20-80%; (2) Preparation of organic-inorganic hybrid cross-linking agent: Prepare an aqueous solution of polyvinyl alcohol with a mass concentration of 1-20%, and then add inorganic salts accounting for 50-200% of the mass of the polyvinyl alcohol used in the aqueous solution of polyvinyl alcohol to obtain a transparent organic-inorganic hybrid cross-linking agent; (3) Preparation of starch hydrogel: According to the ratio of the absolute dry mass of starch to the mass of polyvinyl alcohol being 4:1, add the organic-inorganic hybrid cross-linking agent obtained in step (2) to the phosphorylated starch obtained in step (1), and add an aqueous solution of borax with a mass concentration of 1-10% (the dosage is 1-10% of the sum of the absolute dry mass of starch and the mass of polyvinyl alcohol), and mix well for 0.5-5 h to make the phosphorylated starch and the cross-linking agent fully self-cross-link to obtain an organic-inorganic hybrid starch-based colloid; (4) Antifreeze modification: Add an antifreeze accounting for 1-50% of the sum of the absolute dry mass of starch and the mass of polyvinyl alcohol to the starch-based colloid obtained in step (3), and physically act for 10-60 min to obtain a composite starch-based colloid; (5) Starch hydrogel fermentation: Uniformly add yeast accounting for 1-5% of the sum of the absolute dry mass of starch and the mass of polyvinyl alcohol to the composite starch-based colloid obtained in step (4). After physically acting for 10-60 min, ferment at 10-50 °C for 0.5-48 h to obtain a starch composite hydrogel with a three-dimensional reticular structure.
[0027] Among them, the starch in step (1) includes one or more of corn starch, potato starch, bean starch, wheat starch, etc. The phosphate includes one or more of orthophosphate, pyrophosphate, metaphosphate, tripolyphosphate, etc.
[0028] The inorganic salts in step (2) include one or more of calcium chloride, magnesium chloride, iron chloride, zinc chloride, etc.
[0029] The antifreeze in step (4) includes one or more of ethylene glycol, glycerol, isopropyl alcohol, etc.
[0030] The physical actions in steps (4) and (5) include one or more of physical stirring, kneading, beating, etc.
[0031] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.
[0032] Example 1: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead it for 20 min at room temperature to make it uniformly mixed, and then put it in a sealed glass container and react at 110 °C for 3 h to obtain phosphorylated starch with a concentration of about 60 wt%. (2) Add 15 g of polyvinyl alcohol powder to 85 mL of deionized water, heat and stir it in an oil bath at 95 °C for 0.5 h to obtain a polyvinyl alcohol aqueous solution with a concentration of 15 wt%; then add 15 g of CaCl 2 powder to the polyvinyl alcohol aqueous solution and continue to stir for 10 min to prepare a transparent organic-inorganic hybrid crosslinking agent. (3) Add 20 g of borax to 100 mL of deionized water, heat and stir it in an oil bath at 60 °C for 10 min to obtain a borax aqueous solution with a concentration of 20 wt%; add the organic-inorganic hybrid crosslinking agent prepared in step (2) to the phosphorylated starch obtained in step (1), and add 10 mL of borax aqueous solution, and physically knead it for 30 min at room temperature to make the phosphorylated starch and the crosslinking agent fully self-crosslink to obtain an organic-inorganic hybrid starch-based colloid. (4) Add 25 mL of ethylene glycol solution as an antifreeze to the starch-based colloid obtained in step (3), and physically knead it for 20 min at room temperature to prepare a composite starch-based colloid with conductivity, water retention and antifreeze properties. (5) Take 1.5 g of yeast powder and add it to the composite starch-based colloid in step (3). Physically knead it for 20 min to make it evenly mixed, and then place it under the condition of 30 °C and ferment for 10 h to prepare a conductive water-retaining and freeze-resistant starch composite hydrogel with a three-dimensional network structure and high stretchability.
[0033] Example 2: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead it at room temperature for 20 min to make it evenly mixed, and then put it in a sealed glass container and react at 110 °C for 3 h to obtain phosphorylated starch with a concentration of about 60 wt%. (2) Add 15 g of polyvinyl alcohol powder to 85 mL of deionized water, heat and stir it in an oil bath at 95 °C for 0.5 h to obtain a polyvinyl alcohol aqueous solution with a concentration of 15 wt%. Then add 5 g of CaCl 2 powder to the polyvinyl alcohol aqueous solution and continue to stir for 10 min to prepare a transparent organic-inorganic hybrid crosslinking agent. (3) Add 20 g of borax to 100 mL of deionized water, heat and stir it in an oil bath at 60 °C for 10 min to obtain a borax aqueous solution with a concentration of 20 wt%. Add the organic-inorganic hybrid crosslinking agent prepared in step (2) to the phosphorylated starch obtained in step (1), and add 10 mL of borax aqueous solution. Physically knead it at room temperature for 30 min to make the phosphorylated starch and the crosslinking agent fully self-crosslink to obtain an organic-inorganic hybrid starch-based colloid. (4) Add 25 mL of ethylene glycol solution as an antifreeze agent to the starch-based colloid obtained in step (3), and physically knead it at room temperature for 20 min to prepare a composite starch-based colloid with conductivity, water retention and freeze resistance. (5) Take 1.5 g of yeast powder and add it to the composite starch-based colloid in step (3). Physically knead it for 20 min to make it evenly mixed, and then place it under the condition of 30 °C and ferment for 10 h to prepare a conductive water-retaining and freeze-resistant starch composite hydrogel with a three-dimensional network structure and high stretchability.
[0034] Example 3: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead it at room temperature for 20 min to make it evenly mixed, and then put it in a sealed glass container and react at 110 °C for 3 h to obtain phosphorylated starch with a concentration of about 60 wt%. (2) Add 15 g of polyvinyl alcohol powder to 85 mL of deionized water, heat and stir in an oil bath at 95 °C for 0.5 h to obtain an aqueous polyvinyl alcohol solution with a concentration of 15 wt%; then add 15 g of CaCl 2 powder to the aqueous polyvinyl alcohol solution and continue stirring for 10 min to prepare a transparent organic-inorganic hybrid crosslinking agent; (3) Add 20 g of borax to 100 mL of deionized water, heat and stir in an oil bath at 60 °C for 10 min to obtain an aqueous borax solution with a concentration of 20 wt%; add the organic-inorganic hybrid crosslinking agent prepared in step (2) to the phosphorylated starch obtained in step (1), and add 10 mL of the aqueous borax solution, and physically knead at room temperature for 30 min to allow the phosphorylated starch and the crosslinking agent to fully self-crosslink to obtain an organic-inorganic hybrid starch-based colloid; (4) Add 5 mL of ethylene glycol solution as an antifreeze agent to the starch-based colloid obtained in step (3), and physically knead at room temperature for 20 min to prepare a composite starch-based colloid with conductivity, water retention and antifreeze properties; (5) Take 1.5 g of yeast powder, add it to the composite starch-based colloid in step (3), physically knead for 20 min to mix it evenly, and then place it at 30 °C for fermentation for 10 h to prepare a conductive water-retaining antifreeze starch composite hydrogel with a three-dimensional network structure and high stretchability.
[0035] Comparative Example 1: (1) Take 60 g of corn starch, add 40 mL of deionized water, and physically knead at room temperature for 20 min to mix it evenly; (2) Add 20 g of borax to 100 mL of deionized water, heat and stir in an oil bath at 60 °C for 10 min to obtain an aqueous borax solution with a concentration of 20 wt%.
[0036] (3) Add 10 mL of the aqueous borax solution to the phosphorylated starch obtained in step (1), and physically knead at room temperature for 30 min to obtain a starch-based hydrogel.
[0037] Comparative Example 2: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead at room temperature for 20 min to mix it evenly, and then place it in a sealed glass container and react at 110 °C for 3 h to obtain a phosphorylated starch with a concentration of about 60 wt%; (2) Add 20 g of borax to 100 mL of deionized water, heat and stir in an oil bath at 60 °C for 10 min to obtain an aqueous borax solution with a concentration of 20 wt%.
[0038] (3) Add 10 mL of borax aqueous solution to the phosphorylated starch obtained in step (1), and physically knead for 30 min at room temperature to obtain a phosphorylated starch-based hydrogel.
[0039] Comparative Example 3: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead at room temperature for 20 min to mix evenly, then put it in a sealed glass container and react at 110 °C for 3 h to obtain phosphorylated starch with a concentration of about 60 wt%; (2) Add 15 g of polyvinyl alcohol powder to 85 mL of deionized water, heat and stir in an oil bath at 95 °C for 0.5 h to obtain a 15 wt% polyvinyl alcohol aqueous solution; (3) Add 20 g of borax to 100 mL of deionized water, heat and stir in an oil bath at 60 °C for 10 min to obtain a 20 wt% borax aqueous solution; Add the polyvinyl alcohol aqueous solution obtained in step (2) to the phosphorylated starch obtained in step (1), and add 10 mL of borax aqueous solution, physically knead at room temperature for 30 min to obtain a starch-based colloid with a cross-linked structure.
[0040] Comparative Example 4: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead at room temperature for 20 min to mix evenly, then put it in a sealed glass container and react at 110 °C for 3 h to obtain phosphorylated starch with a concentration of about 60 wt%; (2) Add 15 g of polyvinyl alcohol powder to 85 mL of deionized water, heat and stir in an oil bath at 95 °C for 0.5 h to obtain a 15 wt% polyvinyl alcohol aqueous solution; then add 15 g of CaCl 2 powder to the polyvinyl alcohol aqueous solution and continue to stir for 10 min to prepare a transparent organic-inorganic hybrid cross-linking agent; (3) Add 20 g of borax to 100 mL of deionized water, heat and stir in an oil bath at 60 °C for 10 min to obtain a 20 wt% borax aqueous solution; Add the organic-inorganic hybrid cross-linking agent prepared in step (2) to the phosphorylated starch obtained in step (1), and add 10 mL of borax aqueous solution, physically knead at room temperature for 30 min to allow the phosphorylated starch and the cross-linking agent to fully self-cross-link to obtain an organic-inorganic hybrid starch-based colloid.
[0041] Comparative Example 5: (1) Take 60 g of corn starch, add 1 g of sodium orthophosphate and 40 mL of deionized water, physically knead for 20 min at room temperature to make them evenly mixed, then put it in a sealed glass container and react at 110 °C for 3 h to obtain phosphorylated starch with a concentration of about 60 wt%. (2) Add 15 g of polyvinyl alcohol powder to 85 mL of deionized water, heat and stir in an oil bath at 95 °C for 0.5 h to obtain a polyvinyl alcohol aqueous solution with a concentration of 15 wt%; then add 15 g of CaCl 2 powder to the polyvinyl alcohol aqueous solution and continue to stir for 10 min to prepare a transparent organic-inorganic hybrid crosslinking agent. (3) Add 20 g of borax to 100 mL of deionized water, heat and stir in an oil bath at 60 °C for 10 min to obtain a borax aqueous solution with a concentration of 20 wt%; add the organic-inorganic hybrid crosslinking agent prepared in step (2) to the phosphorylated starch obtained in step (1), and add 10 mL of borax aqueous solution, physically knead at room temperature for 30 min to make the phosphorylated starch and the crosslinking agent fully self-crosslink to obtain an organic-inorganic hybrid starch-based colloid. (4) Add 25 mL of ethylene glycol solution as an antifreeze to the starch-based colloid obtained in step (3), physically knead at room temperature for 20 min to prepare a composite starch-based colloid with conductivity, water retention and antifreeze properties.
[0042] Perform performance tests on the starch hydrogel samples prepared in the examples and comparative examples, and the results are shown in Table 1.
[0043] Table 1
[0044] As can be seen from Table 1, the unphosphorylated pure starch hydrogel (Comparative Example 1) exhibits poor properties such as tensile strain, conductivity, water retention, and low-temperature flexibility; through phosphorylation treatment (Comparative Example 2), the tensile and conductive properties of the starch composite hydrogel can be improved to a certain extent, but its water retention effect is not good and it does not have flexibility at low temperatures; through modification with polyvinyl alcohol (Comparative Example 3), the tensile properties of the starch composite hydrogel can be further improved, but its water retention effect is still not good and it does not have flexibility at low temperatures; through modification with an organic-inorganic hybrid crosslinking agent (Comparative Example 4), the tensile and conductive properties of the starch composite hydrogel can be greatly improved, but its water retention effect is still not good and it cannot maintain good flexibility under high and low temperature conditions; on this basis, through the combined modification with an antifreeze agent (Comparative Example 5), the water retention performance of the starch composite hydrogel can be improved, enabling it to maintain good conductivity and flexibility under both high and low temperature conditions, but due to the uneven dispersion of the added substances in the starch hydrogel, the conductive and tensile properties are not yet good enough. In contrast, the examples utilize the synergistic modification of phosphorylated starch, an organic-inorganic hybrid crosslinking agent, and an antifreeze agent, which can effectively improve the tensile, conductive, and water retention properties of the starch composite gel, and the fermentation treatment further improves the tensile and conductive properties of the gel. This enables the electronic devices prepared based on this starch hydrogel to be used in harsh environments and scenarios with complex deformations, and thus it shows great application prospects in the fields of flexible electronic skin, energy storage devices, etc.
[0045] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.
Claims
1. A method for preparing an organic-inorganic hybrid starch composite hydrogel, characterized in that: The following steps are involved: (1) Starch phosphorylation: Add starch to water and phosphate, mix well and react to obtain phosphorylated starch; (2) Preparation of organic-inorganic hybrid crosslinking agent: adding inorganic salt to polyvinyl alcohol aqueous solution to obtain a transparent organic-inorganic hybrid crosslinking agent; (3) Preparation of starch hydrogel: adding the organic-inorganic hybrid crosslinking agent obtained in step (2) to the phosphorylated starch obtained in step (1), and adding a borax aqueous solution, and mixing thoroughly to obtain an organic-inorganic hybrid starch-based colloid; (4) Antifreeze agent modification: adding an antifreeze agent to the starch-based colloid obtained in step (3) to obtain a composite starch-based colloid through physical action; (5) Starch hydrogel fermentation: Yeast is uniformly added to the composite starch-based colloid obtained in step (4), and after physical action and fermentation, a starch composite hydrogel with a three-dimensional network structure is obtained.
2. The method for preparing an organic-inorganic hybrid starch composite hydrogel according to claim 1, characterized in that: The phosphate in step (1) includes one or more of orthophosphate, pyrophosphate, metaphosphate, and tripolyphosphate, and the amount added is 0.1-10% of the absolute dry mass of starch; the reaction temperature is 80-155°C, and the reaction time is 1-10 h; the mass concentration of the obtained phosphorylated starch is 20-80%.
3. The method for preparing an organic-inorganic hybrid starch composite hydrogel according to claim 1, characterized in that: The mass concentration of the polyvinyl alcohol aqueous solution in step (2) is 1-20%; the inorganic salt includes one or more of calcium chloride, magnesium chloride, ferric chloride, and zinc chloride, and the added amount thereof is 50-200% of the mass of the polyvinyl alcohol used.
4. The method for preparing an organic-inorganic hybrid starch composite hydrogel according to claim 1, characterized in that: The amount of the organic-inorganic hybrid crosslinking agent and the phosphorylated starch in step (3) is calculated based on the ratio of the absolute dry mass of starch to the mass of polyvinyl alcohol of 4:1; the mass concentration of the borax aqueous solution is 1-10%, and the amount added is 1-10% of the sum of the absolute dry mass of the starch and the mass of the polyvinyl alcohol used; and the mixing time is 0.5-5 h.
5. The method for preparing an organic-inorganic hybrid starch composite hydrogel according to claim 1, characterized in that: The antifreeze agent in step (4) includes one or more of ethylene glycol, glycerol, and isopropanol, and the amount added is 1-50% of the sum of the absolute dry mass of the starch used and the mass of the polyvinyl alcohol.
6. The method for preparing an organic-inorganic hybrid starch composite hydrogel according to claim 1, characterized in that: In step (5), the amount of yeast added is 1-5% of the sum of the absolute dry mass of starch and the mass of polyvinyl alcohol used; the fermentation temperature is 10-50° C. and the fermentation time is 0.5-48 h.
7. The method for preparing an organic-inorganic hybrid starch composite hydrogel according to claim 1, characterized in that: The physical action in steps (4) and (5) includes one or more of physical stirring, kneading, and beating, and the action time is 10-60 minutes.
8. An organic-inorganic hybrid starch composite hydrogel prepared by the method as claimed in claim 1.