Aerogel with concentric pores and its preparation method and application

Abstract

This invention belongs to the field of materials science and technology and relates to an aerogel with concentric circular channels, its preparation method, and applications. The preparation method involves dispersing a hydrophilic fiber material and a hydrophobic fiber material in water, shearing the material with a shearing machine to obtain a fiber suspension, freezing the fiber suspension until completely frozen, and freeze-drying the suspension to obtain the aerogel. The hydrophilic fiber material has a water contact angle of 20° to 90°, a shear stiffness of 10 to 20, and an aspect ratio of ≤10; the hydrophobic fiber material has a water contact angle of 100° to 120°, a shear stiffness of 10 to 20, and an aspect ratio of ≥40. The mass ratio of the hydrophilic fiber material to the hydrophobic fiber material is 2 to 4:1. The shear rate of the shearing machine is 15,000 to 25,000 rpm, and the supercooling degree during freezing is ≤3°C. The aerogel with concentric circular channels is produced using this method, and the aerogel can be used as an antifreeze layer in cold environments, for example. The method is simple and has low preparation costs.

Description

Technical Field

[0001] The invention belongs to the field of material science and technology, and relates to an aerogel with concentric circular channels, a preparation method and an application thereof. Background Art

[0002] With the rapid development of materials science, the demand for new functional materials is becoming increasingly urgent. Among them, aerogels with concentric pore structures, due to their unique physical and chemical properties, show great potential for application in a variety of fields, including catalysis, adsorption, separation, energy conversion and management, and biomedicine. The core of this material lies in its ability to provide a highly ordered and controllable pore system. This structure not only promotes efficient material transport and diffusion, improving reaction rates and efficiency, but also facilitates the efficient management and conversion of energy such as light, heat, and electricity.

[0003] In the preparation process of concentric pore aerogel, precise control of the pore structure is the key to achieving its excellent performance. However, existing preparation methods usually involve complex chemical reactions and precise control conditions, as disclosed in the literature (Controlling ice formation on gradient wettability surface for high-performance bioinspired materials[J]. Science Advances, 2020, 6(31): 4712), by designing a surface with a wettability gradient on a two-dimensional cold source surface for freezing, an aerogel with a long-range ordered lamellar structure can be prepared. Furthermore, by freezing a surface with a radial wettability gradient, an aerogel with a concentrically arranged lamellar structure can be obtained. However, this method is limited by the height of ice crystal growth and the change in wettability of the cold source surface, resulting in a complex preparation process and difficulty in precise control.

[0004] Furthermore, existing preparation methods place high demands on the equipment's freezing capacity and surface properties, which not only increases the complexity and technical difficulty of the preparation process but also significantly increases the production cost. This high cost not only limits the widespread application of concentric pore aerogels but also hinders their promotion in the commercialization process. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art and provide an aerogel with concentric circular channels and a preparation method and application thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing an aerogel having concentric circular pores comprises dispersing a hydrophilic fiber material and a hydrophobic fiber material in water, shearing the fiber suspension with a shearing machine, freezing the fiber suspension until completely frozen, and freeze-drying the aerogel.

[0008] The water contact angle of the hydrophilic fiber material is 20°~90°, the shear stiffness is 10~20, and the aspect ratio is ≤10; the water contact angle of the hydrophobic fiber material is 100°~120°, the shear stiffness is 10~20, and the aspect ratio is ≥40; the mass ratio of the hydrophilic fiber material to the hydrophobic fiber material is 2~4:1; the shear rate of the shearing machine is 15000~25000rpm; the supercooling degree during freezing (supercooling degree is the difference between the theoretical crystallization temperature of the crystal and the actual given crystallization site temperature. The magnitude of supercooling degree is closely related to the cooling rate. The faster the cooling rate, the lower the actual crystallization temperature and the greater the supercooling degree; conversely, the slower the cooling rate, the smaller the supercooling degree and the closer the actual crystallization temperature is to the theoretical crystallization temperature) is ≤3°C.

[0009] As the preferred technical solution:

[0010] In the above-mentioned method for preparing an aerogel having concentric circular channels, the aspect ratio of the hydrophilic fiber material is 1-10, and the aspect ratio of the hydrophobic fiber material is 40-80.

[0011] In the above-mentioned method for preparing an aerogel having concentric circular pores, the hydrophilic fiber material is cellulose fiber or cellulose derivative fiber (such as cellulose acetate fiber).

[0012] In the above-mentioned method for preparing an aerogel having concentric circular pores, the hydrophobic fiber material is thermoplastic polyurethane fiber, polylactic acid fiber or polycaprolactone fiber.

[0013] In the above-mentioned method for preparing an aerogel having concentric circular pores, the content of the hydrophilic fiber material in the fiber suspension is 0.67-0.8 wt %.

[0014] In the above-mentioned method for preparing an aerogel having concentric pores, the fiber suspension further contains 0.25 to 2 wt% of a surfactant, so that the surface energy can be adjusted, and thus the size of the pore structure can be controlled.

[0015] In the above-mentioned method for preparing an aerogel having concentric circular pores, freezing the fiber suspension until it is completely frozen means allowing the fiber suspension to stand at -50 to -196° C. for 0.2 to 8 hours.

[0016] The present invention also provides an aerogel having concentric circular pores, which is prepared by using the method for preparing an aerogel having multi-oriented pores as described in any one of the above items.

[0017] The present invention also provides an application of the aerogel having concentric circular pores as described above, which can be used as an antifreeze layer in cold environments, an evaporative cooling system, a water evaporation-driven energy device, a high-speed fluid transport system, a self-cleaning antifouling layer, a multilayer tissue scaffold in tissue engineering, a building sound insulation layer, or a bioreactor carrier;

[0018] Aerogels with concentric pore structures exhibit exceptional performance when used as antifreeze layers in cold environments, evaporative cooling systems, water evaporation-driven energy devices, high-speed fluid transport systems, and self-cleaning antifouling layers. The hydrophilic outer layer of the pore structure provides a surface for water molecules to easily aggregate, increasing the surface area for water evaporation while promoting heat transfer and water vapor transport, effectively accelerating the evaporation process and preventing ice formation. Meanwhile, the hydrophobic inner layer effectively prevents water from penetrating the material, playing a key role in antifreeze and de-icing. Furthermore, the concentric pore structure provides a relatively smooth flow path for fluids, resulting in low flow resistance, which is particularly beneficial for high-speed fluid transport. The hydrophilic outer layer also prevents contaminants from adhering to the material surface, while the hydrophobic inner layer allows water droplets to easily roll off the surface, further preventing water penetration and achieving an antifouling and self-cleaning effect. This aerogel design combines multiple functions, including antifreeze, evaporation promotion, fluid transport, and antifouling and self-cleaning, enabling it to perform exceptionally well in a variety of application scenarios.

[0019] When used as a scaffold for multi-layered tissues (such as skin, hair, and hollow organs) in tissue engineering, aerogels with concentric pore structures have shown significant advantages. The concentric structure of this aerogel has multiple channels, which is highly consistent with the layered growth characteristics of tissues such as skin, hair, and hollow organs. Taking the skin as an example, it is composed of multiple layers of cells. Starting from the basal layer (germinal layer), the cells undergo continuous division and proliferation, and gradually move to the surface to eventually form the stratum corneum. This layered growth pattern is consistent with the layered structure of the concentric pore structure. In addition, the concentric circle structure can effectively promote the directional growth of hair. In the hair follicle, stem cells are located in the basal layer. They differentiate and proliferate along specific directions, eventually forming various parts of the hair. This directional growth mechanism is crucial for the normal development and function of hair. The concentric circle pore structure provides a favorable growth environment for these stem cells, thereby contributing to the healthy growth of hair. Therefore, aerogels with concentric circle pore structures have broad application prospects in tissue engineering and can be applied to artificial organs, hair growth and other fields, providing new possibilities and solutions for the development of these fields.

[0020] When used as a bioreactor carrier, the unique concentric pore structure of aerogels plays a key role. Since the biofilm formed by bacteria exhibits a complex concentric structure, this allows us to optimize the production process of compounds such as enzymes and antibiotics by finely manipulating the microbial community within the concentric pore structure. This structural design not only improves the efficiency of biological reactions, but also makes the production process more controllable and efficient.

[0021] When used as a building sound insulation layer, concentric pore aerogel has good acoustic properties and can effectively isolate noise and vibration, providing a strong guarantee for creating a quiet living and working environment.

[0022] Therefore, aerogels with concentric pore structures have broad application prospects in the field of bioreactors.

[0023] Principle of the invention:

[0024] Under high-speed shear, hydrophilic fiber materials with small aspect ratios are greatly affected by shear flow, and their arrangement direction near the wall (distance from the wall ≤ 1mm) is close to parallel to the Z axis (the angle with the Z axis is close to 0°). Hydrophobic fiber materials with large aspect ratios are less affected by shear flow. The farther away from the wall (the closer to the Z axis), the more the fiber arrangement tends to be oriented towards the initial fluid flow direction, and the angle with the Z axis is closer to 90°. All fiber materials are distributed in a circular pattern from the periphery to the inner circle. The more hydrophilic the hydrophilic fiber material is, the more it is in the outer circle (such as Figure 1 As shown, the outermost circle is the hydrophilic fiber layer 1), and the more hydrophobic the hydrophobic fiber material is, the closer it is to the central axis (as shown in FIG. Figure 1 As shown, the innermost circle is the hydrophobic fiber layer 2). Under low supercooling, ice crystals grow in a disk shape. The hydrophilic and hydrophobic gradient formed by the hydrophilic and hydrophobic fiber material pulls the ice crystal layer to extend from the periphery to the central axis, thus forming a Figure 1 The ring-shaped ice crystals 3 shown have concentric circular channels after freeze-drying.

[0025] Beneficial effects:

[0026] The preparation method of the aerogel with concentric circular channels of the present invention is simple. The prepared aerogel with concentric circular channels can be used for antifreeze in cold environments, evaporative cooling, and promoting water evaporation in energy devices, reducing resistance in high-speed fluid transport, preventing contamination attachment in self-cleaning antifouling layers, simulating tissue layered growth in tissue engineering scaffolds, and optimizing microbial communities in bioreactors, thereby exhibiting excellent multifunctional performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of aerogel with concentric circular channels;

[0028] Figure 2This is a top view of the aerogel with concentric circular channels of Example 1 (the lines in the figure represent the distribution of the concentric circular channels);

[0029] Among them, 1-hydrophilic fiber layer, 2-hydrophobic fiber layer, 3-ring ice crystal. DETAILED DESCRIPTION

[0030] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0031] Example 1

[0032] A method for preparing an aerogel having concentric circular pores, comprising the following steps:

[0033] (1) Preparation of raw materials;

[0034] Hydrophilic fiber material: cellulose fiber, water contact angle of 20° to 80°, shear stiffness of 10 to 20, aspect ratio of 1 to 10;

[0035] Hydrophobic fiber material: thermoplastic polyurethane fiber, water contact angle of 100° to 110°, shear stiffness of 10 to 20, aspect ratio of 40 to 80;

[0036] Surfactant: blocked water-based isocyanate, manufactured by Changzhou Houding Chemical Co., Ltd., China, model number HD-8035;

[0037] water;

[0038] (2) The hydrophilic fiber material, the hydrophobic fiber material and the surfactant were dispersed in water, and the fiber suspension was obtained by shearing with a shearing machine (shear rate of 15000 rpm). The fiber suspension was then allowed to stand at -50 °C (supercooling degree of 1 °C) for 8 h, and freeze-dried (temperature of -45 °C, pressure of 15 Pa, time of 24 h) to obtain the aerogel;

[0039] The mass ratio of the hydrophilic fiber material to the hydrophobic fiber material is 2:1; the content of the hydrophilic fiber material in the fiber suspension is 0.67 wt %, and the content of the surfactant is 0.25 wt %.

[0040] The final aerogel with concentric pores is as follows Figure 2 As shown, it can be used as an antifreeze layer in cold environments, an evaporative cooling system and a water evaporation-driven energy device, a high-speed fluid transport system, a self-cleaning antifouling layer, a multilayer tissue scaffold in tissue engineering, or a bioreactor carrier.

[0041] Example 2

[0042] A method for preparing an aerogel having concentric circular pores, comprising the following steps:

[0043] (1) Preparation of raw materials;

[0044] Hydrophilic fiber material: cellulose acetate fiber, water contact angle of 30° to 80°, shear stiffness of 10 to 20, and aspect ratio of 1 to 10;

[0045] Hydrophobic fiber material: polylactic acid fiber, water contact angle of 100°~120°, shear stiffness of 10~15, aspect ratio of 40~80;

[0046] Surfactant: potassium lauryl ether phosphate, CAS number 58318-92-6;

[0047] water;

[0048] (2) The hydrophilic fiber material, the hydrophobic fiber material and the surfactant were dispersed in water, and the fiber suspension was obtained by shearing with a shearing machine (shear rate of 20000 rpm). The fiber suspension was then allowed to stand at -70 °C (supercooling degree of 2 °C) for 6 h, and freeze-dried (temperature of -50 °C, pressure of 20 Pa, time of 36 h) to obtain the aerogel;

[0049] The mass ratio of the hydrophilic fiber material to the hydrophobic fiber material is 3:1; the content of the hydrophilic fiber material in the fiber suspension is 0.75 wt %, and the content of the surfactant is 1 wt %.

[0050] The resulting aerogel with concentric pores can be used as an antifreeze layer in cold environments, an evaporative cooling system and a water evaporation-driven energy device, a high-speed fluid transport system, a self-cleaning antifouling layer, a multilayer tissue scaffold in tissue engineering, or a bioreactor carrier.

[0051] Example 3

[0052] A method for preparing an aerogel having concentric circular pores, comprising the following steps:

[0053] (1) Preparation of raw materials;

[0054] Hydrophilic fiber material: hydroxypropyl cellulose fiber, water contact angle of 60° to 90°, shear stiffness of 10 to 15, aspect ratio of 5 to 10;

[0055] Hydrophobic fiber material: polycaprolactone fiber, water contact angle of 100°~120°, shear stiffness of 10~12, aspect ratio of 40~80;

[0056] Surfactant: Lauramidopropyl hydroxysulfobetaine, CAS number 13197-76-7;

[0057] water;

[0058] (2) The hydrophilic fiber material, the hydrophobic fiber material and the surfactant were dispersed in water, and the fiber suspension was obtained by shearing with a shearing machine (shear rate of 25000 rpm). The fiber suspension was then allowed to stand at -196 °C (supercooling degree of 3 °C) for 0.2 h, and freeze-dried (temperature of -60 °C, pressure of 40 Pa, time of 48 h) to obtain an aerogel;

[0059] The mass ratio of the hydrophilic fiber material to the hydrophobic fiber material is 4:1; the content of the hydrophilic fiber material in the fiber suspension is 0.8 wt %, and the content of the surfactant is 2 wt %.

[0060] The resulting aerogel with concentric pores can be used as an antifreeze layer in cold environments, an evaporative cooling system and a water evaporation-driven energy device, a high-speed fluid transport system, a self-cleaning antifouling layer, a multilayer tissue scaffold in tissue engineering, or a bioreactor carrier.

[0061] Example 4

[0062] A method for preparing an aerogel having concentric circular channels is basically the same as that of Example 3, except that no surfactant is added in step (2).

[0063] The resulting aerogel with concentric pores can be used as an antifreeze layer in cold environments, an evaporative cooling system and a water evaporation-driven energy device, a high-speed fluid transport system, a self-cleaning antifouling layer, a multilayer tissue scaffold in tissue engineering, or a bioreactor carrier.

Claims

1. A method for preparing an aerogel having concentric circular channels, characterized in that: The hydrophilic fiber material and the hydrophobic fiber material are dispersed in water, sheared by a shearing machine to obtain a fiber suspension, and then the fiber suspension is frozen until completely frozen, and freeze-dried to obtain an aerogel; The water contact angle of the hydrophilic fiber material is 20°~90°, the shear stiffness is 10~20, and the aspect ratio is ≤10; the water contact angle of the hydrophobic fiber material is 100°~120°, the shear stiffness is 10~20, and the aspect ratio is ≥40; the mass ratio of the hydrophilic fiber material to the hydrophobic fiber material is 2~4:1; the shear rate of the shearing machine is 15000~25000rpm; the supercooling degree during freezing is ≤3°C; The fiber suspension also contains 0.25~2wt% of a surfactant.

2. The method for preparing an aerogel having concentric circular channels according to claim 1, characterized in that: The aspect ratio of the hydrophilic fiber material is 1~10, and the aspect ratio of the hydrophobic fiber material is 40~80.

3. The method for preparing an aerogel having concentric circular channels according to claim 1, characterized in that: The hydrophilic fiber material is cellulose fiber or cellulose derivative fiber.

4. The method for preparing an aerogel having concentric circular channels according to claim 1, wherein: The hydrophobic fiber material is thermoplastic polyurethane fiber, polylactic acid fiber or polycaprolactone fiber.

5. The method for preparing an aerogel having concentric circular channels according to claim 1, characterized in that: In the fiber suspension, the content of the hydrophilic fiber material is 0.67~0.8wt%.

6. The method for preparing an aerogel having concentric circular channels according to claim 1, wherein: Freezing the fiber suspension until it is completely frozen means leaving the fiber suspension at -50 to -196°C for 0.2 to 8 hours.

7. An aerogel having concentric circular channels, characterized in that: The aerogel having multi-oriented pores is prepared by the preparation method of any one of claims 1 to 6.

8. The use of the aerogel having concentric circular pores according to claim 7, characterized in that: It can be used as an antifreeze layer in cold environments, an evaporative cooling system and a water evaporation-driven energy device, a high-speed fluid transport system, a self-cleaning antifouling layer, a multilayer tissue scaffold in tissue engineering, a building sound insulation layer or a bioreactor carrier.

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