A porous hydrogel and a preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JILIN VOCATIONAL COLLEGE OF IND & TECH
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-23
AI Technical Summary
Existing porous hydrogel preparation techniques suffer from problems such as template residue or uncontrollable pore structure, making it difficult to construct interconnected and size-controllable porous structures inside the hydrogel, which affects water transport paths and photothermal conversion performance.
A nanofiber framework was pre-constructed using electrospinning technology, and in-situ pore-forming was achieved through a bio-fermentation process. CO2 bubbles generated by yeast were used to form a multi-level porous structure in the electrospinned material, and an interpenetrating network structure was formed through a freeze-thaw cycle.
The controllable construction of porous hydrogels and the uniform distribution of functional fillers were achieved, which improved the mechanical properties and photothermal conversion capacity of hydrogels and increased the efficiency of interfacial water evaporation.
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Figure CN122252104A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrogel technology, specifically providing a porous hydrogel, its preparation method, and its application. Background Technology
[0002] Interfacial solar-driven water evaporation technology has attracted much attention due to its enormous application potential in seawater desalination, wastewater treatment, and industrial wastewater concentration. The core of this technology lies in developing photothermal conversion materials capable of efficiently absorbing sunlight and converting it into heat energy, while simultaneously achieving rapid water transport and evaporation. Hydrogels, as soft materials with a hydrophilic three-dimensional network structure, exhibit significant advantages in constructing efficient interfacial evaporators due to their excellent water retention and tunable physicochemical properties.
[0003] Ideally, a hydrogel for photothermal evaporation should possess the following characteristics: a broad-spectrum, high-absorption-rate photothermal conversion capability; sufficient water transport channels to maintain continuous evaporation; and good structural stability and mechanical strength to withstand practical application environments. Currently, researchers are enhancing the photothermal conversion performance of hydrogels by introducing carbon-based materials (such as carbon nanotubes and graphene) into the hydrogel matrix. However, how to construct interconnected and size-controllable porous structures within the hydrogel to optimize water transport pathways and reduce enthalpy of evaporation, while ensuring that the mechanical properties of the composite material do not significantly decrease due to the introduction of porous structures, remains a major challenge in this field.
[0004] Existing techniques for preparing porous hydrogels mainly include template methods, freeze-drying methods, phase separation methods, and foaming methods. However, these methods often have limitations: for example, template methods are difficult to completely remove template agents, which may introduce impurities; freeze-drying methods are energy-intensive and the pore structure is usually isotropic; traditional chemical foaming methods are difficult to control and tend to produce closed-pore structures, which are not conducive to the directional transport of water. Therefore, there is an urgent need to develop a preparation method that is simple in process, has a controllable structure, and can simultaneously improve the mechanical properties, photothermal conversion efficiency, and water transport capacity of hydrogels. Summary of the Invention
[0005] This invention aims to at least partially address one of the technical problems in the prior art. Therefore, one objective of this invention is to provide a porous hydrogel, its preparation method, and its applications, to solve problems such as template residue or uncontrollable pore structure in the prior art.
[0006] In a first aspect, the present invention provides a method for preparing a porous hydrogel, comprising:
[0007] (1) The first mixture is electrospun to obtain an electrospun material. The first mixture includes carbon-based materials, polyvinyl alcohol, yeast, glucose, and water. The mass ratio of polyvinyl alcohol to water is 1:(10-15).Figure 1 ;
[0008] (2) The second mixture and the electrospinning material are brought into contact and composited to obtain a composite structure. The second mixture includes carbon-based material, polyvinyl alcohol, yeast, glucose and water. The mass ratio of polyvinyl alcohol to water is 1:(2-10).
[0009] (3) The composite structure is fermented and then freeze-thawed to obtain a porous hydrogel.
[0010] According to the method for preparing the porous hydrogel provided by the present invention, a first mixture and a second mixture, both containing polyvinyl alcohol, water, glucose, and carbon-based materials, are first prepared. Then, the first mixture is processed into an electrospun material with a nanowire or nanorod structure using a high-voltage electrospinning process. Next, the electrospun material is combined with the second mixture to form a composite structure. Finally, the composite structure is fermented at a suitable temperature. Using yeast gas production and the guidance of the electrospun nanostructure, a rich porous structure is formed inside the material. After fermentation, the material is subjected to a freeze-thaw cycle to obtain a composite porous hydrogel with an interpenetrating network structure.
[0011] Specifically, after obtaining the composite structure, fermentation is carried out. The yeast in the second mixture utilizes glucose to produce gas, generating a large number of CO2 bubbles. Simultaneously, the nanofiber structure in the electrospun material guides the directional growth of the bubbles, forming an interconnected microporous structure within the material. During fermentation, the unspun second mixture gradually gels and partially diffuses into the electrospun material layer, forming a preliminary composite hydrogel.
[0012] This invention creatively combines electrospinning with bio-fermentation to achieve the controllable construction of a hierarchical porous structure and the uniform dispersion of functional fillers, thereby significantly improving the mechanical properties and photothermal conversion capacity of the hydrogel. Its interconnected internal channels facilitate rapid water transport and significantly enhance interfacial water evaporation efficiency, showing broad application prospects in seawater desalination, wastewater treatment, and other fields. Furthermore, this method is simple, convenient, low-cost, and easy to implement and promote.
[0013] In some embodiments of the present invention, in step (1), the electrospinning material is a nanowire or nanorod structure.
[0014] In some embodiments of the present invention, the mass ratio of polyvinyl alcohol to water in the first mixture is different from the mass ratio of polyvinyl alcohol to water in the second mixture.
[0015] In some embodiments of the present invention, the carbon-based materials in steps (1) and (2) respectively include at least one of nanotubes and graphene.
[0016] In some embodiments of the present invention, the number average molecular weight of the polyvinyl alcohol in steps (1) and (2) is 1700-1800.
[0017] In some embodiments of the present invention, the mass ratio of glucose to water in steps (1) and (2) is independently 1:(30-90).
[0018] In some embodiments of the present invention, the mass ratio of the carbon-based material to the water in steps (1) and (2) is independently 1:(60-200).
[0019] In some embodiments of the present invention, the yeast mass fraction in the first mixture is 0.1-3%.
[0020] In some embodiments of the present invention, the yeast mass fraction in the second mixture is 0.1-3%.
[0021] In some embodiments of the present invention, the composite method in step (2) includes: alternatingly stacking the electrospinning material and the second mixture in a vertical direction or alternatingly stacking the electrospinning material and the second mixture in a horizontal direction.
[0022] As an example, refer to Figure 2 The electrospun material obtained by electrospinning the first mixture is alternately layered with the second mixture. In order to maintain the shape of the second mixture, a container can be used to fix it so that it maintains a constant temperature contact surface with the electrospun material and overcomes its fluidity.
[0023] As an example, refer to Figure 3 A composite structure with alternating layers along the horizontal direction can be prepared by directional filling. The electrospun material is placed in the center of a hollow glass tube, and the glass tube is placed in a container. A second mixture is filled between the glass tube and the container wall. After the first fermentation, the glass tube is removed, allowing the two materials to come into contact and further ferment to form a layered hydrogel structure with a fixed shape.
[0024] In some embodiments of the present invention, in step (3), the fermentation temperature is 30~40℃ and the fermentation time is 5-8h.
[0025] In some embodiments of the present invention, the freeze-thaw process includes freezing and thawing.
[0026] In some embodiments of the present invention, the freezing temperature is -25°C to -15°C, and the freezing time is 10-15 hours;
[0027] In some embodiments of the present invention, the thawing temperature is room temperature, and the thawing time is 1-3 hours;
[0028] In some embodiments of the present invention, the freezing and thawing cycles are repeated 2-4 times.
[0029] In a second aspect, the present invention provides a porous hydrogel prepared by the above method.
[0030] Preferably, the hydrogel comprises, from top to bottom, an electrospun layer, a hydrogel layer, an electrospun layer, a hydrogel layer, an electrospun layer, a hydrogel layer, and an electrospun layer, wherein the hydrogel A layer is formed of an electrospun material, and the hydrogel layer is formed of a second mixture; more preferably, the hydrogel layer encapsulates the electrospun layer.
[0031] Preferably, the hydrogel comprises, from left to right, a hydrogel layer, an electrospinning layer, and another hydrogel layer, wherein the hydrogel layer is formed by a second mixture, and the electrospinning layer is formed by an electrospinning material; more preferably, the hydrogel layer encapsulates the electrospinning layer.
[0032] Those skilled in the art will understand that the present invention does not impose a particular limitation on the number of hydrogel A layer and hydrogel B layer, as long as the two are stacked alternately. Those skilled in the art can select the specific number of layers according to actual needs.
[0033] In a third aspect, the present invention provides an interfacial water evaporation device comprising the aforementioned porous hydrogel.
[0034] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:
[0035] By pre-constructing a nanofiber framework using electrospinning technology and then combining it with in-situ pore creation during bio-fermentation, a controllable construction of hierarchical porous structures and uniform distribution of functional fillers were achieved. This method not only simplifies the preparation process of porous hydrogels and avoids problems such as template residue or uncontrollable pore structures, but also results in hydrogels with good internal pore connectivity, synergistic improvement in mechanical properties and photothermal conversion capacity, and can significantly improve interfacial water evaporation efficiency, showing broad application prospects in seawater desalination, wastewater treatment, and other fields.
[0036] The porous hydrogel provided by this invention, when used for interfacial water evaporation, has interconnected pores that facilitate rapid water transport, and the uniform distribution of carbon-based materials endows it with excellent photothermal conversion capabilities, which can significantly improve the efficiency of interfacial water evaporation. Attached Figure Description
[0037] Figure 1 This is a schematic diagram of the preparation process for preparing electrospun materials according to an embodiment of the present invention;
[0038] Figure 2 This is a schematic diagram of the preparation process of the porous hydrogel in Example 1 of the present invention;
[0039] Figure 3 This is a structural diagram of the porous hydrogel of Embodiment 1 of the present invention;
[0040] Figure 4 This is a schematic diagram of the preparation process of the porous hydrogel in Example 2 of the present invention;
[0041] Figure 5 This is a structural diagram of the porous hydrogel in Embodiment 2 of the present invention. Detailed Implementation
[0042] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.
[0043] Example 1
[0044] This embodiment provides a porous hydrogel with alternating layers in a vertical direction, as shown in the reference. Figure 2 The specific preparation process is as follows:
[0045] Step 1: Prepare the first mixture
[0046] Following a polyvinyl alcohol (PVA) to water mass ratio of 1:12, 5g of PVA was added to 60g of deionized water and heated and stirred in a 90℃ water bath for 2 hours until completely dissolved. After the solution cooled to room temperature, 0.5g of glucose (glucose to water mass ratio of 1:120), 0.1g of carbon nanotubes (CNTs, carbon-based material to water mass ratio of 1:600), and 0.2g of yeast powder were added and stirred evenly to obtain the first mixture.
[0047] Step 2: Prepare the second mixture
[0048] According to the PVA to water mass ratio of 1:6, 10g of PVA was added to 60g of deionized water and heated and stirred in a 90℃ water bath for 2 hours until completely dissolved. After the solution cooled to room temperature, 0.5g of glucose (glucose to water mass ratio of 1:120), 0.1g of CNTs (carbon-based material to water mass ratio of 1:600), and 0.3g of yeast powder were added and stirred evenly to obtain the second mixture.
[0049] Step 3: Electrospinning to prepare nanofiber materials
[0050] The first mixture was loaded into a syringe equipped with a stainless steel needle and fixed to a pusher. The pusher speed was set to 0.5 mL / h, the distance between the needle and the collection plate was 15 cm, and a high voltage of 18 kV was applied. Electrospinning was performed under ambient conditions of 25°C and 40% relative humidity to collect nanofiber mats (nanowire structures).
[0051] Step 4: Layered alternating superposition and composite
[0052] Use a square petri dish as a molding mold. First, pour a layer of the second mixture, approximately 2 mm thick, into the bottom of the mold. Then, cut the electrospun nanofiber felt obtained in step 3 to an appropriate size and lay it flat on top of the second mixture. Next, pour another layer of the second mixture, approximately 2 mm thick, on top of the fiber felt, ensuring that the second mixture completely wets and coats the electrospun material. Repeat the above steps twice to ultimately form a three-layer composite structure with alternating layers of "second mixture - electrospun material - second mixture". (Refer to [reference needed]). Figure 3 .
[0053] Step 5: Fermentation treatment
[0054] The culture dish containing the composite structure was placed in a 35°C constant temperature incubator and allowed to ferment statically for 6 hours. During this process, the yeast in the second mixture utilized glucose to produce gas, generating a large number of CO2 bubbles; simultaneously, the nanofiber structure in the electrospun material guided the bubbles to grow in a directional manner, forming an interconnected microporous structure within the material. During fermentation, the unspun second mixture gradually gelled and partially diffused into the electrospun material layer, forming a preliminary composite hydrogel.
[0055] Step 6: Freeze-thaw cycle
[0056] The fermented composite hydrogel was removed from the culture dish and frozen at -20°C for 12 hours, then thawed at room temperature for 2 hours. This freeze-thaw cycle was repeated three times to allow the PVA molecular chains to form a stable physical cross-linked network through hydrogen bonding, resulting in a composite porous hydrogel with an interpenetrating network structure.
[0057] Example 2
[0058] This embodiment provides a horizontally layered, alternating porous hydrogel structure, prepared using a directional filling method combined with glass tube assistance, as referenced. Figure 4 The specific process is as follows:
[0059] Step 1: Prepare the first mixture
[0060] Following a polyvinyl alcohol (PVA) to water mass ratio of 1:12, 4g of PVA was added to 48g of deionized water and heated and stirred in a 90℃ water bath for 2 hours until completely dissolved. After the solution cooled to room temperature, 0.4g of glucose (glucose to water mass ratio of 1:120), 0.08g of carbon nanotubes (CNTs, carbon-based material to water mass ratio of 1:600), and 0.15g of yeast powder were added and stirred evenly to obtain the first mixture.
[0061] Step 2: Prepare the second mixture
[0062] According to the PVA to water mass ratio of 1:6, 10g of PVA was added to 60g of deionized water and heated and stirred in a 90℃ water bath for 2 hours until completely dissolved. After the solution cooled to room temperature, 0.6g of glucose (glucose to water mass ratio of 1:100), 0.12g of CNTs (carbon-based material to water mass ratio of 1:500), and 0.3g of yeast powder were added, and the mixture was stirred evenly to obtain the second mixture.
[0063] Step 3: Electrospinning to prepare nanofiber materials
[0064] The first mixture was loaded into a syringe equipped with a stainless steel needle and fixed to a pusher. The pusher speed was set to 0.4 mL / h, the distance between the needle and the collection plate was 15 cm, and a high voltage of 20 kV was applied. Electrospinning was performed under ambient conditions of 25°C and 45% relative humidity to collect nanofiber mats (nanorubber structures).
[0065] Step 4: Oriented filling composite
[0066] Use a 50mL beaker as the forming container. Place a 15mm diameter hollow glass tube vertically in the center of the beaker and secure the bottom with a small amount of Vaseline. Cut the electrospun nanofiber felt obtained in step 3 to an appropriate size and fill the center of the glass tube. Then, slowly inject the second mixture prepared in step 2 into the annular gap between the glass tube and the beaker wall until the liquid level is flush with the upper edge of the glass tube, ensuring the second mixture completely surrounds the electrospun material outside the glass tube.
[0067] Step 5: Initial fermentation and removal of the glass tube
[0068] The beaker containing the composite structure was placed in a 35°C incubator and allowed to ferment for 2 hours. At this time, the yeast in the second mixture began to produce gas, the solution viscosity increased, and a preliminary gel state was formed, exhibiting a certain degree of self-support. The beaker was then removed, and the hollow glass tube was carefully pulled vertically upwards to expose the previously isolated central area, allowing the electrospun material in the center to come into direct contact with the surrounding second mixture.
[0069] Step 6: Continue fermentation
[0070] The beaker with the glass tube removed was placed back into the 35°C constant temperature incubator and allowed to continue fermentation for 6 hours. During this process, the second mixture further aerated and gelled, while some of the ungelled liquid diffused into the central electrospun material region. The CO2 bubbles produced by the yeast formed interconnected channels under the guidance of the nanofibers, achieving deep fusion of the two materials and the construction of a porous structure.
[0071] Step 7: Freeze-thaw cycle
[0072] The fermented composite hydrogel was removed from the beaker and frozen at -20°C for 12 hours, then thawed at room temperature for 2 hours. This freeze-thaw cycle was repeated four times to allow the PVA molecular chains to form a stable physical cross-linked network, resulting in a composite porous hydrogel with an interpenetrating network structure. For the specific structure, please refer to [reference needed]. Figure 5 .
[0073] Comparative Example 1
[0074] Comparative Example 1 uses the second mixture from Example 1 to prepare a conventional hydrogel. The thickness of the hydrogel prepared in Comparative Example 1 is the same as that in Example 1.
[0075] The water evaporation performance of Example 1 and Comparative Example 1 was tested. Compared with Comparative Example 1, the evaporation rate of the device in Example 1 was increased by about 5%.
[0076] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a porous hydrogel, characterized in that, include: (1) Electrospinning the first mixture to obtain an electrospun material, wherein the first mixture comprises carbon-based material, polyvinyl alcohol, yeast, glucose and water, and the mass ratio of polyvinyl alcohol to water is 1:(10-15). (2) The second mixture and the electrospinning material are brought into contact and composited to obtain a composite structure. The second mixture includes carbon-based material, polyvinyl alcohol, yeast, glucose and water. The mass ratio of polyvinyl alcohol to water is 1:(2-10). (3) The composite structure is fermented and then freeze-thawed to obtain a porous hydrogel.
2. The method according to claim 1, characterized in that, In step (1), the electrospinning material is a nanowire or nanorod structure; And / or, the mass ratio of polyvinyl alcohol to water in the first mixture is different from the mass ratio of polyvinyl alcohol to water in the second mixture.
3. The method according to claim 1, characterized in that, The carbon-based materials mentioned in steps (1) and (2) each independently include at least one of nanotubes and graphene; And / or, the number average molecular weight of the polyvinyl alcohol in steps (1) and (2) is 1700-1800.
4. The method according to any one of claims 1-3, characterized in that, The mass ratio of glucose to water in steps (1) and (2) is independently 1:(30-90); And / or, the mass ratio of the carbon-based material to the water in steps (1) and (2) is independently 1:(60-200).
5. The method according to any one of claims 1-3, characterized in that, The yeast mass fraction in the first mixture is 0.1-3%; And / or, the yeast mass fraction in the second mixture is 0.1-3%.
6. The method according to any one of claims 1-3, characterized in that, The composite method in step (2) includes: alternatingly stacking the electrospinning material and the second mixture in a vertical direction or alternatingly stacking the electrospinning material and the second mixture in a horizontal direction.
7. The method according to any one of claims 1-3, characterized in that, In step (3), the fermentation temperature is 30~40℃, and the fermentation time is 5-8h; And / or, the freeze-thaw process includes freezing and thawing.
8. The method according to claim 7, characterized in that, The freezing temperature is -25℃ to -15℃, and the freezing time is 10-15 hours. And / or, the thawing temperature is room temperature, and the thawing time is 1-3 hours; And / or, the freezing and thawing cycles are repeated 2-4 times.
9. A porous hydrogel, characterized in that, Prepared by the method described in any one of claims 1-8; Preferably, the hydrogel comprises, from top to bottom, an electrospun layer, a hydrogel layer, an electrospun layer, a hydrogel layer, an electrospun layer, a hydrogel layer, and an electrospun layer, wherein the hydrogel A layer is formed of an electrospun material, and the hydrogel layer is formed of a second mixture; more preferably, the hydrogel layer encapsulates the electrospun layer. Preferably, the hydrogel comprises, from left to right, a hydrogel layer, an electrospinning layer, and another hydrogel layer, wherein the hydrogel layer is formed by a second mixture, and the electrospinning layer is formed by an electrospinning material; more preferably, the hydrogel layer encapsulates the electrospinning layer.
10. An interfacial water evaporation device, characterized in that, Includes the porous hydrogel of claim 9.