Recyclable cold storage phase change composite material and aerogel phase change cold storage material with real-time temperature monitoring function, and preparation method and application thereof

Abstract

The present application relates to the technical field of new material preparation, in particular to a recyclable aerogel phase change cold storage material with real-time temperature monitoring function and a preparation method and application thereof.The recyclable cold storage phase change composite material comprises a polymer aerogel and a phase change material loaded in the polymer aerogel; the polymer in the polymer aerogel contains a structural unit of a maleic anhydride group and a structural unit of a maleimide group, the recyclable cold storage phase change composite material can be recycled, has a smaller leakage amount, and can maintain a low temperature for a long time; the recyclable cold storage phase change material with real-time temperature monitoring function has a layer structure, comprising an inner layer formed by the recyclable cold storage phase change composite material and an outer layer formed by a second polymer aerogel, and can simultaneously realize mass temperature monitoring and recyclable performance.

Description

Technical Field

[0001] This invention relates to the field of new material preparation technology, specifically to a recyclable cold storage phase change composite material, a recyclable aerogel phase change cold storage material with real-time temperature monitoring function, and its preparation method and application. Background Technology

[0002] In recent years, the demand for cold energy has grown rapidly, making cryogenic energy storage extremely attractive. There are two common refrigeration methods: active refrigeration, such as refrigeration and freezing equipment that uses electricity, like refrigerators or freezers; and passive refrigeration, such as refrigerators, cooler bags, and iceboxes that use phase change materials (PCMs) for cooling. Active refrigeration methods like refrigerators are costly, and controlling and reducing consumption while improving system efficiency has become a primary task for researchers in this field. Passive refrigeration methods, such as refrigerators and PCMs, can utilize off-peak electricity or green energy sources like solar power for cold storage, representing a promising development direction. Among numerous energy storage technologies, methods utilizing solid-liquid transitions based on PCMs to store large amounts of energy have been implemented in various refrigeration applications, such as food storage, transportation, and air conditioning. PCMs have high energy storage density, providing a compact and feasible solution to address the supply-demand imbalance. PCMs are mainly divided into organic and inorganic PCMs. Compared to inorganic PCMs, organic PCMs have received more attention in practical applications due to their non-toxicity, slight supercooling, and good cycle stability. However, organic phase change materials (PCMs) pose a risk of leakage when used directly as energy storage materials, making encapsulation essential to prevent such leaks. Furthermore, the reprocessability and recyclability of organic PCMs must be considered to avoid environmental pollution and resource waste.

[0003] Therefore, how to provide a recyclable cold storage phase change composite material with low leakage and recyclability is a technical problem that needs to be solved in this field. Summary of the Invention

[0004] To address the technical problems in the prior art, the present invention provides a recyclable cold storage phase change composite material, its preparation method and application. This recyclable cold storage phase change composite material not only has cold storage capacity but can also be recycled and reused. At the same time, it has the characteristic of low leakage. Based on this, the present invention also provides a recyclable cold storage phase change composite material with real-time temperature monitoring function, which not only has cold storage capacity, recyclability, and low leakage but also has real-time temperature monitoring function.

[0005] A first aspect of the present invention is to provide a recyclable cold-storage phase change composite material, comprising a polymer aerogel and a phase change material loaded in the polymer aerogel; wherein the polymer in the polymer aerogel contains structural units with maleic anhydride groups and structural units with maleimide groups.

[0006] According to the present invention, the content of phase change material and polymer aerogel in the recyclable cold storage phase change composite material can be selected within a wide range. In a preferred embodiment of the present invention, based on the total mass of the recyclable cold storage phase change composite material as 100%, the content of polymer aerogel is 2%-20%, preferably 4%-10%, for example, it can be 4%, 5%, 6%, 7%, 8%, 9%, 10%, and any two values ​​or any range of any two values; the content of phase change material is 80%-98%, preferably 90%-96%.

[0007] Preferably, the total mass of the polymer aerogel and the phase change material is 100%.

[0008] According to the present invention, the phase change material can be selected from a wide range, as long as it has cold storage performance. The phase change material includes, but is not limited to, organic phase change materials. Preferably, the phase change temperature of the organic phase change material is (-10)-30℃, and / or the latent heat of phase change is 55-280J / g. More preferably, it is an alkane organic phase change material, and even more preferably, it is at least one of decadecane, dodecane, and tetradecane.

[0009] In a preferred embodiment of the present invention, under the temperature condition that the phase change material is in a liquid state, the leakage of the phase change material in the recyclable cold storage phase change composite material is less than 10 wt%, preferably less than 5 wt%, and more preferably less than 2 wt%.

[0010] According to the present invention, the polymer aerogel can be anisotropic or isotropic.

[0011] The difference between anisotropic and isotropic aerogels lies in their pore structure. Anisotropic aerogels exhibit long-range order in their pore structure, primarily due to the directional growth of ice crystals during the pre-freezing stage. During this growth, impurities (the polymer in this invention) are expelled, and the accumulation of these impurities forms the pore walls. Subsequent freeze-drying removes the ice, resulting in a porous aerogel. Therefore, different unidirectional cold source temperatures during pre-freezing can yield anisotropic aerogels. Various methods can be used to implement the unidirectional cold source temperature, including, but not limited to, using liquid nitrogen as the cryogenic cold source during pre-freezing. The pre-freezing container is placed on a copper column immersed in liquid nitrogen, allowing ice crystals to grow upwards from the bottom of the container, ultimately forming an anisotropic porous aerogel.

[0012] Anisotropic aerogels have different pore structures, varying axial and radial thermal conductivity, and different rates of mass and sound transmission. Anisotropic or isotropic aerogels can be selected based on different applications. For example, in the encapsulation of phase change materials in this invention, the inventors discovered that using a preferred anisotropic aerogel significantly reduces leakage, without requiring specific orientation of the anisotropic aerogel.

[0013] In a preferred embodiment of the present invention, the polymer aerogel is an anisotropic aerogel, preferably an anisotropic aerogel obtained by different unidirectional cold source temperatures during pre-freezing. In this preferred embodiment, under the temperature condition that the phase change material is in a liquid state, the leakage of the phase change material in the recyclable cold storage phase change composite material is lower.

[0014] In a preferred embodiment of the present invention, the polymer aerogel can be dissolved in ammonia water at 0-150°C to form a polymer-containing solution. Preferably, the polymer-containing solution can be recycled to obtain the polymer aerogel by pre-freezing, freeze-drying, and heat treatment.

[0015] In a preferred embodiment of the present invention, the thermal conductivity of the polymer aerogel is below 0.05 W / (m·K), preferably below 0.04 W / (m·K). The polymer aerogel of the present invention has the characteristic of low thermal conductivity and can be used directly as a thermal insulation material without any treatment.

[0016] In a preferred embodiment of the present invention, the density of the polymer aerogel is 100 kg / m³. 3 The preferred values ​​are 10-100 kg / m³. 3 The preferred value is 15-80 kg / m³. 3 Specifically, for example, 15kg / m 3 35kg / m 3 45kg / m 3 55kg / m 3 65kg / m 3 75kg / m 3 80kg / m 3 The polymer aerogel contains any two values ​​or any range of two values; and / or, the polymer aerogel is a porous material. The polymer aerogel of this invention has high porosity and is a porous material that can be used as a carrier. For example, it can be used as a framework to support organic phase change materials, preventing leakage of the phase change material. The prepared phase change composite material can also be recovered using ammonia.

[0017] In a preferred embodiment of the present invention, with the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups being 100%, the proportion of structural units containing maleimide groups in the polymer is 5%-70%, preferably 10%-60%; more preferably 20%-50%, for example 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any two values ​​or any range of any two values.

[0018] According to the present invention, the polymer can be selected from a wide range of sources. In a preferred embodiment of the present invention, the polymer is derived from a polymer raw material having one or more of the structural units having maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups.

[0019] Maleic anhydride group refers to The maleimide group refers to Maleic acid and ammonium salt groups, maleamic acid and ammonium salt groups refer to In the formula, M may be the same or different, and each can be a hydroxyl group, an amino group, or an ammonium group (-ONH4).

[0020] Preferably, the polymer raw material is a copolymer of a polymeric monomer having one or more of the following groups: maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups, and an olefinic monomer; more preferably, the olefinic monomer is at least one of α-methylstyrene, styrene, and isobutylene.

[0021] In a preferred embodiment of the present invention, the polymer aerogel is soluble in ammonia water at 0-150°C to form a polymer-containing solution; preferably, the polymer-containing solution is pre-frozen, freeze-dried, and heat-treated to recover the polymer aerogel. Based on this, the polymer aerogel of the present invention can be conveniently and environmentally recycled.

[0022] In a preferred embodiment of the present invention, the polymer aerogel possesses photoluminescent properties and its light signal changes with temperature. The photoluminescent properties of the polymer aerogel in this invention can also be used as an indicator material for displaying temperature changes.

[0023] In a preferred embodiment of the present invention, the static water contact angle of the polymer aerogel is above 100°, preferably above 110°, and more preferably above 135°. In a preferred embodiment of the present invention, the polymer aerogel is insoluble in water; preferably, after immersing the polymer aerogel in water at 20-40°C for 24 hours, preferably 72 hours, and more preferably 168 hours, it will not dissolve to form an aqueous polymer solution. The polymer aerogel of the present invention possesses superoleophilic and hydrophobic properties, and can be directly used as an oil-water separation material without any treatment.

[0024] In a preferred embodiment of the present invention, the preparation method of the polymer aerogel includes reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under closed conditions, followed by pre-freezing, freeze drying, and heat treatment for dehydration and deammoniation to obtain the polymer aerogel.

[0025] The aerogel preparation method of this invention only requires heat treatment of the water-soluble aerogel, avoiding the introduction of crosslinking agents or hydrophobic treatment to prepare hydrophobic and water-resistant aerogels. The preparation method is simple, easy to implement, environmentally friendly, and applicable to the preparation of various types of maleimide copolymer aerogels. No crosslinking agent is added in the aerogel preparation method of this invention.

[0026] A second aspect of the present invention is to provide a method for preparing the recyclable cold-storage phase change composite material described in the first aspect, comprising loading the phase change material in the polymer aerogel; preferably, the polymer aerogel is prepared first, and then the phase change material is loaded in the polymer aerogel.

[0027] The method for loading the phase change material into the polymer aerogel can be any existing loading method in the prior art. Specifically, it can be achieved by loading the phase change material into the composite aerogel by filling or injecting the phase change material in a liquid state, thereby allowing the phase change material to be adsorbed and / or permeated.

[0028] The preparation method of polymer aerogel includes reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under closed conditions, followed by pre-freezing, freeze drying, and heat treatment to dehydrate and remove ammonia, thereby obtaining the polymer aerogel.

[0029] The aerogel preparation method of the present invention only requires heat treatment of water-soluble aerogel, avoiding the introduction of crosslinking agents or hydrophobic treatment to prepare hydrophobic and water-resistant aerogels. The preparation method is simple, easy to implement, green and environmentally friendly, and applicable to the preparation of various types of maleimide copolymer aerogels.

[0030] In a preferred embodiment of the present invention, the preparation method includes the following steps: (1) reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water under closed conditions to obtain a polymer aqueous solution; (2) pre-freezing the polymer aqueous solution obtained in step (1) and then freeze-drying it to obtain a water-soluble polymer (i.e., a polymer aerogel precursor); (3) heat-treating the water-soluble polymer obtained in step (2) to obtain the polymer aerogel.

[0031] According to the present invention, the amounts of polymer raw materials and ammonia in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, in step (1):

[0032] Based on the total mass of the reaction system (100%), the mass fraction of polymer raw materials is 0.1%-30%, preferably 1%-10%, more preferably 2%-5%. Based on the mass of ammonia in ammonia water, the mass fraction of ammonia in the raw materials is 0.001%-30%, preferably 0.01%-10%, more preferably 0.1%-1%. The remaining component is water.

[0033] According to the present invention, the reaction conditions in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, the reaction conditions include: a reaction temperature of 0-200°C, preferably 50-150°C, more preferably 80-100°C, and / or a reaction time of 0.01-100h, preferably 0.5-10h, more preferably 1-5h.

[0034] In a preferred embodiment of the present invention, step (2) includes pre-freezing the polymer aqueous solution obtained in step (1) in a pre-freezing container to obtain ice. The pre-freezing container can be of any shape and size and can be customized according to the required aerogel. Freezing can be performed using a refrigerator or other cold source, or using liquid nitrogen. If the cold source temperature is the same in all directions of the pre-freezing container, the prepared aerogel is isotropic; if the cold source temperature is different in all directions of the pre-freezing container, an anisotropic aerogel can be prepared. Preferably, different unidirectional cold source temperatures during pre-freezing can yield anisotropic aerogels. There are various options for the implementation of the unidirectional cold source temperature, including but not limited to using liquid nitrogen as a low-temperature cold source during pre-freezing, placing the pre-freezing container on a copper column immersed in liquid nitrogen, and allowing ice crystals to grow upwards from the bottom of the container.

[0035] Specifically, the pre-freezing conditions can be conventional temperature conditions in the art. The present invention does not have any particular limitations, as long as the polymer aqueous solution is frozen into ice.

[0036] According to the present invention, the freeze-drying conditions can be selected within a wide range, and the present invention is not particularly limited. In a preferred embodiment of the present invention, the freeze-drying conditions include: a temperature below -10°C, for example, below -20°C or below -30°C; and a vacuum degree in the freeze-drying process, which can be selected within a wide range. In a preferred embodiment of the present invention, the vacuum degree is below 1000 Pa, for example, below 100 Pa or below 10 Pa. The above freeze-drying conditions can be flexibly selected based on cost, efficiency, and the conventional operating mode of the equipment.

[0037] The freeze-drying process can utilize various existing freeze-drying equipment, such as freeze dryers, freeze spray dryers, and industrial freeze dryers.

[0038] According to the present invention, the heat treatment conditions in step (3) can be selected within a wide range. In a preferred embodiment of the present invention, the heat treatment conditions in step (3) include:

[0039] The temperature is 100-300℃, preferably 130-200℃, more preferably 150-190℃, and / or the time is 0.1-10h, preferably 0.5-3h, more preferably 1-2h. The reaction pressure is not particularly limited, but is preferably carried out at atmospheric pressure.

[0040] According to the present invention, the polymer raw material can be selected from a wide range. In a preferred embodiment of the present invention, the polymer raw material is a polymer having one or more of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups; preferably, the polymer raw material is a copolymer of a polymeric monomer having one or more of the polymeric monomers having maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups and an olefin monomer; more preferably, the olefin monomer includes at least one of α-methylstyrene, styrene, isobutylene, and vinyl acetate.

[0041] For example, the polymer raw material includes, but is not limited to, at least one of styrene-maleic anhydride copolymer, methylstyrene-maleic anhydride copolymer, and maleic anhydride isobutylene copolymer.

[0042] The polymer raw materials described above are all polymers that have been disclosed in the prior art. They can be obtained from commercially available polymers or prepared according to methods disclosed in the prior art.

[0043] The material of the sealed container is not particularly limited in this invention, and it can be a container made of metal, non-metal, polymer, or other materials.

[0044] More specifically, the preparation process of the polymer aerogel of the present invention includes the following steps: a) reacting a polymer raw material containing at least one of the structural units of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups with ammonia water in a closed container and heating to prepare a polymer aqueous solution; b) pouring the polymer aqueous solution into a pre-freezing container, then pre-freezing it until it is completely frozen into ice, and then freeze-drying it in a freeze dryer for a certain period of time to obtain a water-soluble polymer; c) subjecting the water-soluble polymer to heat treatment under constant temperature conditions to dehydrate and deammoniate to obtain a water-resistant maleimide-based aerogel.

[0045] During pre-freezing, the cold source temperature of the solution in each direction may be the same or different. More preferably, the cold source temperature of the solution in each direction is different during pre-freezing, resulting in anisotropic aerogel. Most preferably, the cold source temperature of the pre-frozen solution is different in one direction, resulting in anisotropic aerogel.

[0046] In a preferred embodiment of the present invention, during the pre-freezing stage, the cold source temperature of the polymer aqueous solution obtained in step (1) is different in each direction, preferably different in one direction.

[0047] In a more preferred embodiment of the invention, before pre-freezing in step (2), a mold is inserted into the polymer aqueous solution obtained in step (1). The mold can be inserted to the bottom of the pre-freezing container or leave a distance from the bottom of the pre-freezing container, preferably the latter. After heat treatment in step (3), the mold is optionally removed to obtain a polymer aerogel with a cavity. In step (4), a phase change material is filled into the polymer aerogel. In this way, the pre-stored material can be placed in the cavity left after removing the mold, which facilitates storage.

[0048] The mold in this invention can remain in place even when it has a cavity structure, allowing pre-stored items to be placed inside the mold's cavity during use. Simultaneously, placing refrigerated items (such as vaccines, medicines, etc.) inside the cavity ensures a more uniform cooling environment and better preservation.

[0049] The present invention does not impose any particular restrictions on the selection of the mold. The material can be glass, plastic, metal, etc. The mold can be solid or have a cavity structure, and its shape is not limited, but preferably cylindrical or columnar. Regarding the structure of the mold, it can be solid or have a cavity structure when the contents are removed. When the contents are not removed, the mold preferably has a cavity structure that can be opened at the top. The size of the mold can be adjusted according to the size of the pre-stored contents, and the present invention does not impose any particular restrictions.

[0050] The "and / or" in this invention refers to the fact that either one of the two conditions before or after "and / or" can be chosen, or both conditions can coexist.

[0051] Real-time temperature monitoring of phase change materials is also crucial. For example, most vaccines, including COVID-19 vaccines, must be kept below 8°C during transportation and storage; therefore, real-time temperature monitoring of each vaccine is necessary. Organic phase change materials also require consideration of reprocessability and recyclability to avoid environmental pollution and resource waste.

[0052] Based on the above-mentioned technical problems, a third aspect of the present invention is to provide a recyclable cold storage phase change material with real-time temperature monitoring function. The recyclable cold storage phase change material has a layer structure, including an inner layer formed by the recyclable cold storage phase change composite material described in the first aspect or the recyclable cold storage phase change composite material prepared by the preparation method described in the second aspect, and an outer layer formed by a second polymer aerogel.

[0053] According to the present invention, the thickness of the inner layer and the thickness of the outer layer can be selected within a wide range. In a preferred embodiment of the present invention, the thickness of the inner layer is 3 mm or more, and the thickness of the outer layer is 5 mm or more.

[0054] In a preferred embodiment of the present invention, a spacer layer is further provided between the inner layer and the outer layer. The present invention does not impose any particular restrictions on the material of the spacer layer, as long as it can separate the aerogel containing the phase change material internally from the external insulating aerogel, preventing mutual permeation. Materials include, but are not limited to, metals (e.g., thin aluminum foil), plastics, etc.

[0055] The thickness of the inner layer can be controlled during the manufacturing process based on the distance between the mold walls and the bottom of the spacer layer. The thickness of the outer layer can be controlled based on the distance between the spacer layer and the outer container wall.

[0056] The recyclable cold-storage phase change material described above can be a cylindrical structure with a radial layer structure, the outer layer being a second polymer aerogel, the inner layer being a recyclable cold-storage phase change composite material, and a spacer layer between the two layers; or the recyclable cold-storage phase change material can be a plate-shaped structure with a spacer layer in the middle, one side of which is the outer layer of the second polymer aerogel, and the other side is the inner layer of the recyclable cold-storage phase change composite material; preferably, the recyclable cold-storage phase change material is further encapsulated with an encapsulating material. The present invention does not impose any particular restrictions on the shape and structure of the spacer layer; for example, it can be cylindrical or plate-shaped, as long as it can cover the inner aerogel layer and isolate the inner and outer layers.

[0057] Preferably, the inner layer has a cavity; the cavity originates from the mold itself or is formed after the mold is removed. In application, refrigerated items (such as vaccines, medicines, etc.) can also be placed in the cavity, making the refrigerated items in a more uniform cooling environment and improving the preservation effect.

[0058] According to the present invention, the second polymer aerogel can be selected from a wide range. Preferably, the second polymer aerogel has photoluminescence properties (i.e., fluorescence properties) and its light signal changes with temperature. Here, the light signal refers to the position and / or intensity of the fluorescence spectral peak.

[0059] In a preferred embodiment of the present invention, the second polymer aerogel is selected from at least one polymer aerogel in the recyclable cold-storage phase change composite material according to the first aspect, which has photoluminescence properties (i.e., fluorescence properties) and whose light signal changes with temperature; and the second polymer aerogel may be the same as or different from the polymer aerogel in the recyclable cold-storage phase change composite material. More preferably, the second polymer is a styrene-maleic anhydride-maleimide copolymer aerogel (i.e., a copolymer formed by a polymeric monomer having one or more of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups and styrene). The inventors of the present invention have discovered that the styrene-maleic anhydride-maleimide copolymer aerogel has fluorescence properties that allow the light signal to change with temperature.

[0060] As an example, in a specific embodiment of the present invention, the phase change cold storage material of the present invention is characterized by an inner layer being the aerogel phase change composite material described in the first aspect, and an outer layer being a polymer aerogel used in the aerogel phase change composite material described in the first aspect. Preferably, the aerogel has a photoluminescence effect (for example, it can be a styrene-maleic anhydride / maleimide copolymer aerogel), and the intensity changes with temperature (for example, it increases as the temperature decreases). Therefore, the temperature of the phase change material can be determined by measuring the fluorescence intensity, thereby realizing real-time temperature monitoring of the cold storage material.

[0061] A fourth aspect of the present invention is to provide a method for preparing a recyclable cold storage phase change material with real-time temperature monitoring function as described in the third aspect, characterized by comprising the following steps:

[0062] (1) A polymer raw material containing at least one of maleic anhydride, maleimide, maleic acid and ammonium salt, maleamic acid and ammonium salt groups is reacted with ammonia water under closed conditions to obtain a polymer aqueous solution.

[0063] (2) Place the polymer aqueous solution in the space inside the spacer layer or in the space between the spacer layer and the mold, then pre-freeze it, and then freeze-dry it to obtain the water-soluble polymer (i.e., polymer aerogel precursor).

[0064] (3) Heat-treat the water-soluble polymer obtained in step (2), and optionally remove the mold to obtain a polymer aerogel with a cavity;

[0065] (4) Fill the polymer aerogel obtained in step (3) with the phase change material to form the inner layer of the recyclable cold storage phase change material;

[0066] In step (2), step (3), step (4) and / or between steps and / or after step (4), the second polymer aerogel is coated on the outside of the spacer layer to form the outer layer of the recyclable cold storage phase change material.

[0067] or,

[0068] In step (2), an aqueous solution containing the second polymer aerogel and / or an aqueous solution of the second polymer is placed in the space outside the spacer layer to form the outer layer of the recyclable cold storage phase change material; preferably, the aqueous solution of the second polymer is the same as the aqueous solution of the polymer in step (1);

[0069] In other words, step (2) is preferably performed in the following manner:

[0070] The polymer aqueous solution is placed in the space outside the spacer layer, the space inside the spacer layer, or the space between the inside of the spacer layer and the mold to obtain a water-soluble polymer with a layered structure.

[0071] According to the above technical solution, the preparation method of the recyclable cold storage phase change material with real-time temperature monitoring function of the present invention includes a polymer aerogel preparation process. The polymer aerogel (recyclable polymer aerogel) preparation method described above can be used to obtain a polymer aerogel located within the spacer layer. Simultaneously, during the preparation of the inner polymer aerogel, a second polymer aerogel or an aqueous solution containing the second polymer aerogel and / or an aqueous solution containing the second polymer aerogel is coated onto the outside of the spacer layer. The timing of coating the spacer layer with the second polymer aerogel or an aqueous solution containing the second polymer aerogel and / or an aqueous solution containing the second polymer aerogel can be selected based on the type of second polymer aerogel used. For example, when the second polymer aerogel is the polymer aerogel described above (i.e., the same type of polymer aerogel as the inner layer), the water-soluble polymer in step (1) can be placed outside the spacer layer in step (2), and then subsequent processing steps can be performed. In this way, after the processing step in step (3), both inside and outside the spacer layer are recyclable polymer aerogels. If the second polymer aerogel (or precursor) does not need to be freeze-dried but needs to be heat-treated, the second polymer aerogel (or precursor) can also be placed outside the spacer layer in step (2). When the second polymer aerogel (or precursor) does not need to be heat-treated, the finished second polymer aerogel can also be placed outside the spacer layer after step (3) or step (4). In short, based on the principle of saving procedures or processes, the process can be flexibly adjusted according to the type of the second polymer aerogel.

[0072] Specifically, the amount of aerogel raw material used in the inner and outer layers can be selected within a wide range, preferably such that the thickness of the inner layer in the finished product is more than 3 mm and the thickness of the outer layer is more than 5 mm.

[0073] The selection of materials for the second polymer aerogel or (precursor), the selection of materials for the phase change material, and the amount of materials used can be the same as those described in the third aspect, and will not be repeated here.

[0074] In a preferred embodiment of the present invention, the polymer content in the aqueous solution of the inner layer is 0.1%-30% by mass, preferably 1%-10%, more preferably 2%-5%, and / or the aqueous solution of the second polymer aerogel and / or the aqueous solution of the second polymer are each 0.1%-30% by mass, preferably 0.5%-10%, more preferably 1%-5%.

[0075] In a preferred embodiment of the present invention, in step (2), during the pre-freezing stage, the cold source temperatures of the polymer aqueous solution obtained in step (1) are different in all directions, preferably different in one direction. This allows for the formation of anisotropic aerogels, and in this preferred embodiment, the resulting cold storage material exhibits lower leakage.

[0076] The pre-freezing container can be of any shape and size, and can be customized according to the shape of the desired aerogel or refrigerated item. Freezing can be performed using a refrigerator or other cold source, or using liquid nitrogen. If the cold source temperature is uniform in all directions of the mold, the prepared aerogel is isotropic; if the cold source temperature is different in all directions of the pre-freezing container, an anisotropic aerogel can be prepared. This invention preferably produces anisotropic aerogels, and more preferably anisotropic aerogels with different unidirectional cold source temperatures.

[0077] The specific conditions in steps (1), (2), and (3) above can be selected within a wide range, and preferably the preferred conditions in the above-mentioned preparation method for polymer aerogel can be adopted.

[0078] More specifically, in step (3), the heat treatment temperature is 100-300℃, preferably 120-220℃, more preferably 160-200℃; the heat treatment time is 0.1-10 hours, preferably 0.5-3 hours, more preferably 1-2 hours.

[0079] According to the present invention, the method for recovering recyclable polymer aerogel in the above-mentioned recyclable cold storage phase change composite material can be adopted by the following method:

[0080] The recovery method involves mixing and reacting the polymer aerogel and / or materials containing the polymer aerogel with ammonia water under closed conditions until an aqueous solution containing the recovered polymer is obtained. Optionally, insoluble matter is removed to obtain an aqueous solution of the recovered polymer. This aerogel recovery method does not require the introduction of organic solvents or high-temperature, high-pressure stirring treatment. It only requires a certain concentration of ammonia water, preferably maintained below 100 degrees Celsius, to achieve rapid and efficient recovery. This method has low energy consumption, low pollution, and high efficiency. The recovered polymer solution can be reused in the preparation of polymer aerogels.

[0081] The method for recovering polymer aerogel according to the present invention is as follows: the polymer aerogel is placed in ammonia water of a certain concentration and placed in a sealed container, heated at a certain temperature until it is completely dissolved to obtain an aqueous solution of the copolymer.

[0082] According to the present invention, the conditions for the mixing reaction in the recovery method can be selected within a wide range. In a preferred embodiment of the present invention, the temperature of the mixing reaction is 0-200°C, preferably 50-150°C, more preferably 80-100°C, and / or the mixing reaction time is 0.01-100h, preferably 0.5-10h, more preferably 1-5h.

[0083] In a preferred embodiment of the present invention, the recovery method further includes freeze-drying and heat-treating the aqueous solution of the recovered polymer to obtain polymer aerogel; preferably, the freeze-drying conditions include: a temperature below -10°C, which can be below -20°C or below -30°C, and / or a vacuum degree below 1000Pa, which can be below 100Pa or below 10Pa.

[0084] According to the present invention, the conditions for heat treatment can be selected within a wide range. In a preferred embodiment of the present invention, the conditions for heat treatment include:

[0085] The temperature is 100-300℃, preferably 130-200℃, more preferably 150-190℃ and / or the time is 0.1-10h, preferably 0.5-3h, more preferably 1-2h.

[0086] When dealing with the recycling of recyclable cold-storage phase change composite materials and recyclable polymer aerogels in recyclable cold-storage phase change materials with real-time temperature monitoring functions as described in this invention, the above-mentioned method can be used to treat the recyclable cold-storage phase change composite material or the recyclable cold-storage phase change composite material of the inner layer of the recyclable cold-storage phase change material with real-time temperature monitoring function in ammonia water to separate the polymer from the phase change material. After a post-processing step, recyclable polymer aerogels are obtained. Alternatively, the preparation method of recyclable cold-storage phase change composite materials or recyclable cold-storage phase change materials with real-time temperature monitoring functions can be used to obtain the recyclable cold-storage phase change composite material or recyclable cold-storage phase change material with real-time temperature monitoring function as described in this invention.

[0087] When the second polymer aerogel is the recyclable polymer aerogel of this invention (the polymer in the polymer aerogel contains maleic anhydride groups and maleimide groups), it can be recycled together with the inner layer material using the above method. When the second polymer aerogel is a different type of polymer aerogel, the second polymer aerogel on the outer layer of the recyclable cold storage phase change material with real-time temperature monitoring function can be peeled off before proceeding with the subsequent recycling steps.

[0088] The fifth aspect of the present invention is to provide the application of the recyclable cold-storage phase change composite material described in the first aspect or the recyclable cold-storage phase change composite material prepared by the preparation method described in the second aspect, the recyclable cold-storage phase change material with real-time temperature monitoring function described in the third aspect or the recyclable cold-storage phase change material with real-time temperature monitoring function prepared by the preparation method described in the fourth aspect in the fields of food preservation and cold chain transportation.

[0089] According to the above technical solution, this invention provides a recyclable cold storage phase change composite material, a recyclable aerogel phase change cold storage material with real-time temperature monitoring function, its preparation method, and its application. Compared with the prior art, this invention has the following advantages:

[0090] The recyclable cold-storage phase change composite material of this invention includes a polymer aerogel and a phase change material loaded in the polymer aerogel; wherein the polymer in the polymer aerogel contains structural units with maleic anhydride groups and maleimide groups. This polymer aerogel can be recovered in ammonia water, and after post-treatment (including heat treatment), the recovered polymer aerogel can be reused. Based on this, the recyclable cold-storage phase change composite material of this invention can be repeatedly recycled. The recyclable cold-storage phase change composite material of this invention is not only recyclable but also has strong cold storage performance and less leakage of the phase change material, enabling it to maintain low temperatures for extended periods. It can be widely used in food preservation and cold chain transportation (e.g., cold chain transportation of vaccines and pharmaceuticals).

[0091] Furthermore, the recyclable cold-storage phase change material with real-time temperature monitoring function in this invention has a sandwich structure, including an inner layer formed by a recyclable cold-storage phase change composite material and an outer layer formed by a second polymer aerogel. This can achieve better thermal insulation performance. In the preferred case where the second polymer aerogel has photoluminescence properties and the light signal changes with temperature, temperature monitoring can be better achieved. Thus, large-scale temperature monitoring and recyclability can be achieved simultaneously. Attached Figure Description

[0092] Figure 1 Temperature rise curve of the cold storage phase change material obtained in Example 1;

[0093] Figure 1 Test results show that the prepared phase change material can maintain a low temperature for a long time;

[0094] Figure 2 Emission spectrum of maleimide-based aerogel on the outer layer of the phase change cold storage material prepared in Example 1 at an excitation wavelength of 400 nm.

[0095] Figure 2This indicates that the temperature of phase change materials can be monitored in real time through the fluorescence-temperature relationship of surface aerogels.

[0096] Figure 3 This is a schematic diagram showing the appearance of the recyclable cold-storage phase change composite material (a), the recovered phase change material (b), and the recovered polymer aerogel (c) in the recycling embodiment. It can be seen that the recyclable cold-storage phase change composite material of this invention can be recycled and reused.

[0097] Figure 4 This is a three-dimensional structural diagram of the aerogel phase change cold storage material with real-time temperature monitoring function obtained in Example 1.

[0098] Figure 5 This is a schematic diagram of the longitudinal section of the aerogel phase change cold storage material with real-time temperature monitoring function obtained in Example 1.

[0099] Wherein, 1—outer layer; 2—spacer layer; 3—inner layer; 4—cavity. Detailed Implementation

[0100] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0101] The present invention will be further described below with reference to the embodiments; however, the present invention is not limited to these embodiments.

[0102] The experimental data in the examples were measured using the following instruments and methods:

[0103] 1. Example of Leakage Test

[0104] Take 15g of the sample obtained in the example, place filter paper on a 30°C hot plate, invert the sample on the filter paper for 10 minutes, remove the sample, weigh the sample to obtain m (g), and the leakage amount is: m / 15*100wt%. If the sample is completely melted and cannot be removed, the leakage amount is 100wt%.

[0105] 2. Three-dimensional fluorescence spectroscopy test in the example:

[0106] The fluorescence spectrum of the above-mentioned nano-fluorescent elastic particles was measured using an F-7000FL Spectrophotometer, with a wavelength scan mode and an excitation wavelength set to 400 nm.

[0107] 3. Example: Cold storage capacity test of phase change material:

[0108] Add 10 mL of ethanol to a 10 mL glass vial and freeze to -30°C. Then place it in a 25°C constant temperature chamber and insert a thermocouple into the ethanol to evaluate the cold storage effect.

[0109] 4. The water solubility of the aerogel in the example was measured as follows:

[0110] Take 1g of aerogel and place it in 100g of water. Soak it at room temperature for 72 hours, then remove and dry it. Weigh the aerogel to obtain its mass m1. When m1 > 99%, the polymer aerogel is considered water-resistant. When the aerogel completely dissolves in water, it is considered a water-soluble aerogel.

[0111] 5. The water contact angle of the aerogel obtained in the example is measured as follows:

[0112] The water contact angle of the product obtained in the example was measured using a German EASYDROP contact angle tester: the polymer aerogel was cut into pieces of approximately 10*10*2mm using a thin blade. 3 A thin sheet of aerogel is prepared and fixed on the operating table. During the fixing process, the sample is kept flat in the horizontal direction. Then, the glass slide is placed on the sample stage of the EASYDROP contact angle measuring instrument and fixed. The instrument is adjusted to control the volume of water droplets to 4±0.02μL. The water droplets are dropped onto the aerogel surface for 1 minute. The angle between the solid-liquid interface, through the inside of the droplet, and the vapor-liquid interface at the three-phase interface is measured. This is the static water contact angle (abbreviated as water contact angle).

[0113] 6. Method for measuring the thermal conductivity of the aerogel obtained in the example:

[0114] The aerogel was first cut into approximately 30*20*5mm pieces using a TC3100 general-purpose thermal conductivity meter manufactured by Xi'an Xiaxi Electronic Technology Co., Ltd. This was done using a thin blade. 3 Two aerogel sheets were placed on either side of the test probe and pressed down with weights. The test temperature was adjusted to 25 degrees Celsius, and the test method was set as thermal insulation material sample test. The thermal conductivity obtained from the test results was the average of at least 5 measurements.

[0115] 7. Structural characterization method of the aerogel obtained in the examples:

[0116] The aerogels in the examples were tested using a Nicolet IS5 Fourier transform infrared spectrometer (USA). Infrared spectra of the samples were acquired by pressing KBr pellets. A suitable amount of aerogel was ground together with KBr, pressed into pellets, and then tested. The scan number was set to 32, the spectral acquisition range was 400-4000 cm⁻¹, and the optical frequency was 1 cm⁻¹. -1 .

[0117] 8. Structural NMR 1H spectroscopy standard method for the aerogels obtained in the examples:

[0118] The aerogel samples in the examples were analyzed using an Agilent 400-MR DD2 nuclear magnetic resonance spectrometer. 1 ¹H NMR analysis was performed. For the water-soluble aerogel, dimethyl sulfoxide-d6 was used as the solvent, while for the hydrophobic and water-resistant aerogel, acetone-d6 was used as the solvent. Tetramethylsilane (TMS) was used as the internal reference reagent.

[0119] 9. Test method for adsorption capacity of phase change materials:

[0120] The entire sample was weighed using a balance before the test and the weight was m1. After the phase change material was adsorbed and the sample was inverted to dry the excess phase change material, the entire sample was weighed again and the weight was m2. The amount of phase change material adsorbed was m2 - m1.

[0121] 10. The test method for phase transition temperature is as follows:

[0122] The thermal properties of aerogels and phase change materials were measured using differential scanning calorimetry (DSC) with a Perkin-Elmer pyris-1 calibrated using indium and zinc standards. For aerogels, samples were heated from 20 to 150 °C under a nitrogen flow, held at 20 °C and 150 °C for 5 min each. For phase change materials, samples were heated from 50 °C to 300 °C under a nitrogen flow, held at 50 °C and 300 °C for 5 min each. The programmed rate for all heating and cooling processes was 20 °C / min. The latent heat of fusion ΔHm and latent heat of solidification ΔHf, as well as the melting temperature Tm and solidification temperature Tf, were determined based on the correlation peaks of the DSC curves.

[0123] Preparation Example 1

[0124] Polymer preparation in this embodiment of the invention: 500 ml of isoamyl acetate was placed in a 1000 ml three-necked flask, and nitrogen gas was purged for 30 min to remove oxygen. 24.5 g of maleic anhydride and 26 g of styrene were added to the flask. After complete dissolution, 0.4 g of azobisisobutyronitrile was added, and the water bath temperature was raised to 70 °C, and the reaction was carried out for 7 h. After the reaction, the mixture was centrifuged at 10000 r for 10 min, the supernatant was removed, 500 ml of methanol was added, and the mixture was stirred for 0.5 h. After centrifugation, the supernatant was removed, and the process was repeated twice. Then, the mixture was vacuum dried at 140 °C for 24 h to obtain the styrene-maleic anhydride copolymer.

[0125] Example 1

[0126] Add 91.5g of water to a capped glass bottle, then add 3.5g of 25% ammonia and 5g of maleic anhydride-styrene copolymer. Tighten the cap and place the bottle in an oven at 95°C. After 4 hours, remove the bottle to obtain a homogeneous 5% polymer solution.

[0127] Pour 15 ml of polymer solution into a cylindrical aluminum foil spacer with a closed bottom. Fix a 10 ml cylindrical glass vial (as a mold) in the center of the aluminum foil spacer, with the bottom and sides of the vial about 9 mm away from the inner wall of the aluminum foil spacer. Keep the top of the vial about 1 mm above the solution. Then fix the aluminum foil spacer in the center of a 50 ml (cylindrical) beaker (as a pre-freezing container) containing 20 ml of polymer solution, with the bottom of the spacer about 5 mm away from the beaker. Freeze at -30°C for 2 hours. Transfer the frozen sample to a freeze dryer (below -30°C and below 10 Pa) and freeze-dry for 72 hours. Then take out the obtained water-soluble polymer.

[0128] The water-soluble polymer was placed in an oven and heat-treated at 180°C for 2 hours to dehydrate and deaminate, so that both the inner and outer layers obtained maleimide-based polymer aerogels (i.e., the polymer aerogels of this invention).

[0129] The presence of maleimide structures in the polymer aerogel was confirmed by infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Based on a total molar amount of maleic anhydride and maleimide-containing structural units in the polymer aerogel (assuming 100% molarity), the molar proportion of maleimide-containing structural units was 43.6%. The polymer aerogel had a water contact angle of 138.1°, a thermal conductivity of 0.0362 W / (m·K), and a density of 72.3 kg / m³. 3 .

[0130] 11 ml of dodecane phase change material was injected into the inner layer of aerogel until it was filled with excess phase change material. The surface of the aerogel phase change composite material was then wiped clean to obtain a maleimide copolymer aerogel phase change cold storage material.

[0131] When using vaccines, they can be placed in glass bottles.

[0132] Example 2

[0133] Add 91.5g of water to a capped glass bottle, then add 3.5g of 25% ammonia and 5g of maleic anhydride-styrene copolymer. Tighten the cap and place the bottle in an oven at 95°C. After 4 hours, remove the bottle to obtain a homogeneous 5% polymer solution.

[0134] Pour 15 ml of polymer solution into a 25 mL cylindrical container of polytetrafluoroethylene (PTFE) with a copper bottom. Fix a 10 mL cylindrical glass vial (as a mold) in the center of the PTFE cylindrical container, with the bottom and sides of the vial approximately 9 mm from the inner wall of the PTFE cylindrical container. Keep the top of the vial about 1 mm above the solution. Place the PTFE cylindrical container on a copper column immersed in liquid nitrogen. After freezing, remove the frozen polymer solution vial and transfer it to a cylindrical aluminum foil spacer. Fix the aluminum foil spacer in the center of a 50 ml cylindrical beaker containing 20 ml of polymer solution (as a pre-freezing container), with the bottom of the spacer about 5 mm from the beaker. Freeze at -30°C for 2 hours. Transfer the frozen sample to a freeze dryer (below -30°C and below 10 Pa) and freeze-dry for 72 hours. Remove the obtained water-soluble polymer.

[0135] The water-soluble polymer was placed in an oven and heat-treated at 180°C for 2 hours to dehydrate and deaminate, so that both the inner and outer layers were obtained as maleimide-based polymer aerogels, and the inner layer of maleimide-based polymer aerogel was anisotropic.

[0136] 11 ml of dodecane phase change material was injected into the inner layer of aerogel until it was filled with excess phase change material. The surface of the aerogel phase change composite material was then wiped clean to obtain a maleimide copolymer aerogel phase change cold storage material.

[0137] Example 3

[0138] In Example 1, the steps in the preparation of the polymer solution were changed as follows: 94.9g of water was added to a capped glass bottle, followed by 2.1g of ammonia (25% by mass) and 3g of maleic anhydride-styrene copolymer. The bottle cap was tightened and the bottle was placed in an oven at 95°C. After 4 hours, a homogeneous 3% polymer solution was obtained. The other preparation steps were the same as in Example 1, except that 11ml of dodecane was added.

[0139] Example 4

[0140] The dodecane in Example 2 was replaced with tetradecane, and the other preparation steps were the same as in Example 2.

[0141] Example 5

[0142] Add 80g of water to a reaction vessel with a polytetrafluoroethylene inner liner, then add 3.5g of ammonia water with a mass fraction of 25% and 5g of maleic anhydride isobutylene copolymer (Kuraray ISOBAM-08, molecular weight approximately 300,000). After sealing the reaction vessel, place it in an oven at 95°C. After 4 hours, remove the vessel to obtain a homogeneous polymer solution. Dry the solution at room temperature to obtain a polymer containing maleic acid and maleic ammonium groups.

[0143] Take 1g of the above polymer and put it into a glass bottle with a cap. Add 98.96g of water and 0.04g of ammonia solution with a mass fraction of 25%. Tighten the cap of the glass bottle and put it in an oven at 20°C. After 0.5 hours, take it out to obtain a homogeneous polymer solution with a mass fraction of 1%.

[0144] 15 ml of polymer solution was poured into a cylindrical aluminum foil spacer with a closed bottom. A 10 ml cylindrical glass vial (as a mold) was fixed in the center of the aluminum foil spacer, with the bottom and sides of the vial approximately 9 mm from the inner wall of the spacer. The top of the vial was kept approximately 1 mm above the solution. The aluminum foil spacer was then fixed in the center of a 50 ml polytetrafluoroethylene (PTFE) cylindrical container containing 20 ml of the 0.5% polymer solution prepared in Example 1, with the bottom of the spacer approximately 5 mm from the bottom of the PTFE cylindrical container. The container was then placed on a copper column in a liquid nitrogen bath. After pre-freezing, the container was placed in a freeze dryer (below -30°C, below 10 Pa) and freeze-dried for 72 hours to obtain an anisotropic water-soluble polymer. The water-soluble polymer was then heat-treated in an oven at 130°C for 2 hours to dehydrate and deaminate, yielding a maleimide-based polymer aerogel. 11 ml of dodecane phase change material was injected into the inner layer of aerogel until it was filled with excess phase change material. The surface of the aerogel phase change composite material was then wiped clean to obtain a maleimide copolymer aerogel phase change cold storage material.

[0145] The measured leakage, phase change temperature, and latent heat of phase change were similar to those in Example 2.

[0146] Example 6

[0147] Add 80g of water to a reaction vessel with a polytetrafluoroethylene inner liner, then add 3.5g of ammonia water with a mass fraction of 25% and 5g of maleic anhydride isobutylene copolymer (Kuraray ISOBAM-08, molecular weight approximately 300,000). After sealing the reaction vessel, place it in an oven at 95°C. After 4 hours, remove the vessel to obtain a homogeneous polymer solution. Dry the solution at room temperature to obtain a polymer containing maleic acid and maleic ammonium groups.

[0148] Add 91.5g of water to a capped glass bottle, then add 3.5g of 25% ammonia and 5g of the polymer containing maleic acid and ammonium maleate groups obtained above. Tighten the glass bottle cap and place it in an oven at 150°C. After 10 hours, take it out to obtain a homogeneous 5% copolymer aqueous solution.

[0149] Replace the 15 ml polymer solution in Example 2 with the 5% copolymer solution described above in this example, and the other preparation steps are the same as in Example 2.

[0150] The maleimide-based polymer aerogel obtained by dehydration and deammoniation was tested, and then injected into the phase change material according to the steps of Example 2.

[0151] The presence of maleimide structures in the polymer aerogel was confirmed by infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Based on a total molar amount of maleic anhydride and maleimide-containing structural units in the polymer aerogel (assuming 100% molarity), the molar proportion of maleimide-containing structural units was 38.7%. The polymer aerogel had a water contact angle of 127.6°, a thermal conductivity of 0.0369 W / (m·K), and a density of 73.1 kg / m³. 3 .

[0152] The leakage rate, phase change temperature, and latent heat of phase change obtained from the tests on the phase change material were similar to those in Example 2.

[0153] Recycling Examples

[0154] Take 5g of the aerogel phase change material prepared in Example 2 and place it in a sealed glass bottle with a cap. Then add 1g of ammonia water with a mass fraction of 25% and 15g of water. Keep it in a 95°C oven for 2 hours to obtain liquid. Figure 3 In step a), the recovered polymer aqueous solution was obtained by separation using a separatory funnel. Figure 3 c) and phase change materials ( Figure 3 (b)

[0155] The obtained polymer aqueous solution was used as the raw material for preparing aerogel, and the phase change material was used as the raw material for preparing phase change material. The phase change composite material was prepared according to the method of Example 2.

[0156] The measured leakage, phase change temperature, and latent heat of phase change were similar to those in Example 2.

[0157] Table 1

[0158] Sample Name Phase change material adsorption capacity (g) Leakage Example 1 6.21 3.8wt% Example 2 6.64 2.9wt% Example 3 7.57 4.2wt% Example 4 6.72 3.0wt%

[0159] As shown in Table 1, the recyclable cold storage phase change composite material in the embodiments of the present invention has a high adsorption capacity of phase change material and less leakage of phase change material, and can be widely used in food preservation, cold chain transportation (such as cold chain transportation of vaccines and medicines).

[0160] Table 2

[0161]

[0162] As shown in Table 2, the porous aerogel in this invention causes very little latent heat loss to the phase change material, and can be used to prepare phase change composite materials with high cold storage capacity and low leakage.

[0163] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A recyclable cold-storage phase change composite material, comprising a polymer aerogel and a phase change material supported in the polymer aerogel; wherein, The polymer aerogel contains structural units with maleic anhydride groups and structural units with maleimide groups. The phase change material is an alkane-based organic phase change material; Based on the total mass of the recyclable cold storage phase change composite material as 100%, the content of the polymer aerogel is 2%-20%, and the content of the phase change material is 80%-98%.

2. The recyclable cold storage phase change composite material according to claim 1, characterized in that: Based on the total mass of the recyclable cold storage phase change composite material as 100%, the content of the polymer aerogel is 4%-10%, and the content of the phase change material is 90%-96%.

3. The recyclable cold storage phase change composite material according to claim 1, characterized in that: The phase change material has a phase change temperature of -10 to 30°C and / or a latent heat of phase change of 55-280 J / g.

4. The recyclable cold storage phase change composite material according to claim 1, characterized in that: The phase change material is at least one of decadecane, dodecane, and tetradecane.

5. The recyclable cold storage phase change composite material according to claim 1, characterized in that: Under the temperature condition where the phase change material is in a liquid state, the leakage of the phase change material in the recyclable cold storage phase change composite material is less than 10 wt%.

6. The recyclable cold storage phase change composite material according to claim 1, characterized in that: Under the temperature condition where the phase change material is in a liquid state, the leakage of the phase change material in the recyclable cold storage phase change composite material is less than 5 wt%.

7. The recyclable cold storage phase change composite material according to claim 1, characterized in that: Under the temperature condition where the phase change material is in a liquid state, the leakage of the phase change material in the recyclable cold storage phase change composite material is less than 2 wt%.

8. The recyclable cold storage phase change composite material according to claim 1, characterized in that: The polymer aerogel is an anisotropic aerogel; and / or, The polymer aerogel can dissolve in ammonia water at 0-150°C to form a polymer-containing solution; and / or, The density of the polymer aerogel is 100 kg / m³. 3 the following.

9. The recyclable cold storage phase change composite material according to claim 1, characterized in that: The polymer aerogel is an anisotropic aerogel obtained by different unidirectional cold source temperatures during pre-freezing; and / or, The polymer aerogel can be dissolved in ammonia water at 0-150℃ to form a polymer-containing solution. This polymer-containing solution, after pre-freezing, freeze-drying, and heat treatment, can be used to recover the polymer aerogel; and / or, The density of the polymer aerogel is 15-80 kg / m³. 3 .

10. The recyclable cold storage phase change composite material according to claim 1, characterized in that: With the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups being 100%, the molar proportion of structural units containing maleimide groups in the polymer is 5%-70%.

11. The recyclable cold storage phase change composite material according to claim 1, characterized in that: With the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups being 100%, the molar proportion of structural units containing maleimide groups in the polymer is 10%-60%.

12. The recyclable cold storage phase change composite material according to claim 1, characterized in that: With the total molar amount of structural units containing maleic anhydride groups and structural units containing maleimide groups being 100%, the molar proportion of structural units containing maleimide groups in the polymer is 20%-50%.

13. The recyclable cold storage phase change composite material according to claim 1, characterized in that: The polymer is derived from polymer raw materials having maleic anhydride structural units.

14. The recyclable cold storage phase change composite material according to claim 1, characterized in that: The polymer raw material is a copolymer comprising a polymeric monomer having a maleic anhydride group and an olefin monomer.

15. The recyclable cold storage phase change composite material according to claim 14, characterized in that: The olefin monomer is at least one of α-methylstyrene, styrene, and isobutylene.

16. The recyclable cold-storage phase change composite material according to any one of claims 1-15, characterized in that: The polymer aerogel is prepared by reacting polymer raw materials containing maleic anhydride structural units with ammonia water under closed conditions, followed by pre-freezing, freeze drying, and heat treatment for dehydration and deammoniation.

17. The recyclable cold storage phase change composite material according to claim 16, characterized in that: During pre-freezing, the temperature of the cold source in all directions of the solution may be the same or different.

18. The recyclable cold storage phase change composite material according to claim 16, characterized in that: Anisotropic aerogels are obtained when the cold source temperature varies in different directions of the solution during pre-freezing.

19. The recyclable cold storage phase change composite material according to claim 16, characterized in that: The pre-freezing solution has different unidirectional cold source temperatures, resulting in anisotropic aerogels.

20. A method for preparing a recyclable cold-storage phase change composite material according to any one of claims 1-19, comprising loading the phase change material in the polymer aerogel.

21. The preparation method according to claim 20, characterized in that... The preparation method includes the following steps: (1) The polymer raw material containing maleic anhydride structural units is reacted with ammonia water under closed conditions to obtain a polymer aqueous solution; (2) The polymer aqueous solution obtained in step (1) is first pre-frozen and then freeze-dried to obtain a water-soluble polymer; (3) The water-soluble polymer obtained in step (2) is subjected to heat treatment to obtain the polymer aerogel; (4) Load the phase change material in the polymer aerogel.

22. The preparation method according to claim 21, characterized in that: In step (1), the total mass of the reaction system is 100%, the mass fraction of the polymer raw material is 0.1%-30%, the mass fraction of the ammonia in the ammonia water is 0.001%-30%, and the remaining components are water.

23. The preparation method according to claim 21, characterized in that: In step (1), the total mass of the reaction system is 100%, the mass fraction of the polymer raw material is 1%-10%, the mass fraction of the ammonia in the ammonia water is 0.01%-10%, and the remaining components are water.

24. The preparation method according to claim 21, characterized in that: In step (1), the total mass of the reaction system is 100%, the mass fraction of the polymer raw material is 2%-5%, the mass fraction of the ammonia in the ammonia water is 0.1%-1%, and the remaining components are water.

25. The preparation method according to claim 21, characterized in that: During the pre-freezing stage, the cold source temperature varies in different directions for the polymer aqueous solution obtained in step (1); and / or, Before pre-freezing in step (2), the mold is inserted into the polymer aqueous solution obtained in step (1), and after heat treatment in step (3), the mold is optionally removed to obtain a polymer aerogel with a cavity. In step (4), the phase change material is loaded into the polymer aerogel.

26. The preparation method according to claim 21, characterized in that: During the pre-freezing stage, the temperature of the unidirectional cold source of the polymer aqueous solution obtained in step (1) is different.

27. A recyclable cold storage phase change material with real-time temperature monitoring function, the recyclable cold storage phase change material having a layered structure, comprising an inner layer formed by the recyclable cold storage phase change composite material according to any one of claims 1-19 or the recyclable cold storage phase change composite material prepared by the preparation method according to any one of claims 20-26, and an outer layer formed by a second polymer aerogel.

28. The recyclable cold storage phase change material with real-time temperature monitoring function according to claim 27, characterized in that: The inner layer has a thickness of 3 mm or more, and the outer layer has a thickness of 5 mm or more; and / or, A spacer layer is further provided between the inner layer and the outer layer; and / or, The inner layer is provided with a cavity; and / or, The second polymer aerogel has photoluminescence properties and its light signal changes with temperature.

29. The recyclable cold storage phase change material with real-time temperature monitoring function according to claim 27, characterized in that: The second polymer aerogel is selected from at least one polymer aerogel in the recyclable cold storage phase change composite material according to any one of claims 1-19 that has photoluminescence properties and whose light signal changes with temperature, and the second polymer aerogel may be the same as or different from the polymer aerogel in the recyclable cold storage phase change composite material.

30. The recyclable cold storage phase change material with real-time temperature monitoring function according to claim 27, characterized in that: The second polymer is a copolymer of a polymeric monomer having maleic anhydride groups and styrene.

31. A method for preparing a recyclable cold storage phase change material with real-time temperature monitoring function as described in any one of claims 27-30, characterized in that... Includes the following steps: (1) The polymer raw material containing maleic anhydride groups is reacted with ammonia water under closed conditions to obtain a polymer aqueous solution; (2) The polymer aqueous solution is placed in the space inside the spacer layer or in the space between the spacer layer and the mold, then pre-frozen, and then freeze-dried to obtain the water-soluble polymer; (3) Heat-treat the water-soluble polymer obtained in step (2), and optionally remove the mold to obtain a polymer aerogel with a cavity; (4) Load the phase change material into the polymer aerogel obtained in step (3) to form the inner layer of the recyclable cold storage phase change material; In step (2), step (3), step (4) and / or between and / or after step (4), the second polymer aerogel is coated on the outside of the spacer layer to form the outer layer of the recyclable cold storage phase change material; Alternatively, in step (2), an aqueous solution containing the second polymer aerogel and / or an aqueous solution of the second polymer can be placed in the space outside the spacer layer to form the outer layer of the recyclable cold storage phase change material.

32. The preparation method according to claim 31, characterized in that: The second polymer aqueous solution is the same as the polymer aqueous solution in step (1).

33. The preparation method according to claim 30, characterized in that: The polymer content in the inner polymer aqueous solution is 0.1%-30% by mass, and / or, the second polymer content in the aqueous solution of the second polymer aerogel and / or the second polymer aqueous solution is 0.1%-30% by mass; and / or, In step (2), during the pre-freezing stage, the cold source temperature of the polymer aqueous solution obtained in step (1) is different in each direction.

34. The preparation method according to claim 30, characterized in that: The polymer content in the inner polymer aqueous solution is 1%-10% by mass, and / or, the second polymer content in the second polymer aerogel aqueous solution and / or the second polymer aqueous solution is 0.5%-10% by mass; and / or, In step (2), during the pre-freezing stage, the unidirectional cold source temperature of the polymer aqueous solution obtained in step (1) is different.

35. The preparation method according to claim 30, characterized in that: The mass fraction of the second polymer in the aqueous solution of the second polymer aerogel and / or the aqueous solution of the second polymer is 1%-5% each.

36. The application of the recyclable cold-storage phase change composite material according to any one of claims 1-19, or the recyclable cold-storage phase change composite material prepared by the preparation method according to any one of claims 20-26, the recyclable cold-storage phase change material with real-time temperature monitoring function according to any one of claims 27-30, or the recyclable cold-storage phase change material with real-time temperature monitoring function prepared by the preparation method according to any one of claims 31-35 in the fields of food preservation and cold chain transportation.

Images