Recyclable polymer aerogels, cool-storing phase change composite materials, preparation methods and applications

Abstract

The present invention relates to the field of porous materials, particularly to recyclable polymer aerogels, their preparation methods, recovery methods, and uses; recyclable cold-storing phase-change composite materials containing the recyclable polymer aerogels; and recyclable cold-storing phase-change materials with real-time temperature monitoring, their preparation methods, and uses. The polymers in the polymer aerogels contain maleic anhydride group-containing structural units and maleimide group-containing structural units. This invention marks the first time that polymers containing maleimide group-containing structural units have been prepared into aerogels, broadening the range of applications for maleic anhydride group-containing copolymers and maleimide group-containing copolymers. Furthermore, the aerogels prepared by this invention have extremely high recovery efficiency; after dissolution and recovery with aqueous ammonia, the recovery efficiency can exceed 99%. Furthermore, the aerogel preparation and recovery process does not require organic solvents, making them highly efficient, energy-efficient, and environmentally friendly. The recyclable cold-storing phase-change composite materials are recyclable, have low leakage, and can maintain low temperatures for long periods of time. The recyclable heat-storing phase change material with real-time temperature monitoring capability has a layered structure including an inner layer formed of a recyclable heat-storing phase change composite material and an outer layer formed of a second polymer aerogel, which can achieve both temperature monitoring in large batches and recyclability.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to the field of porous materials, and in particular to a recyclable polymer aerogel, its preparation method, recovery method and use thereof, as well as a recyclable cold-storing phase-change composite material comprising the recyclable polymer aerogel, a recyclable cold-storing phase-change material with real-time temperature monitoring function, their preparation methods and their use.

[0002] [Background technology] Polymer aerogels are novel lightweight solid materials formed by the aggregation of colloidal particles or polymer molecules. They have a three-dimensional porous structure, with a gas dispersion medium filling the network of pores. They are characterized by low density, high porosity, and a large specific surface area. Polymer aerogels also have high heat resistance, low thermal conductivity, and a low refractive index. Currently, these materials are widely used in thermal and acoustic insulation materials, adsorption separation, catalysis, energy storage and conversion, sound absorption and insulation, sensor platforms, antifouling and anticorrosion materials, water-resistant fibers, and proton exchange membranes.

[0003] Polymer aerogels are generally prepared by the sol-gel method or the phase separation method. The sol-gel method requires at least three processes: solution-sol conversion, sol-gel conversion, and gel-aerogel conversion. It also requires a time-consuming aging process lasting up to six to seven days. The phase separation method involves first preparing a polymer solution using an organic solvent, then gelling it, followed by the creation of a hydrogel using water instead of the organic solvent, which can then be used to produce aerogels. The drawback of this method is the need to handle large amounts of organic solvent. While polymer aerogels can also be prepared directly using aqueous solutions, the aerogel products require crosslinking and hydrophobic post-treatment, making the process complicated. Clearly, the preparation of polymer aerogels, especially crosslinked low-density polymer aerogels, can cause environmental pollution, while the recycling of the resulting products is difficult. Therefore, as consumption increases, polymer aerogels may experience more serious "white pollution" problems than general plastic products, limiting their industrial application. Clearly, the development of low-pollution, recyclable polymer aerogels is an urgent technological challenge in aerogel technology.

[0004] To achieve hydrophobic and water-resistant properties, polymer aerogels prepared using conventional techniques often require crosslinking and hydrophobic treatment, making the resulting crosslinked aerogels extremely difficult to recycle. Therefore, preparing hydrophobic and water-resistant aerogels without crosslinking is the best way to achieve aerogel recyclability. However, preparing and recycling hydrophobic aerogels typically requires the use of numerous organic solvents, resulting in additional pollution.

[0005] In recent years, the demand for low-temperature energy has rapidly increased, making low-temperature energy storage very attractive. There are two common refrigeration methods: active refrigeration, which utilizes electrical energy, such as refrigerators or freezers, and passive refrigeration, which utilizes phase-change materials for refrigeration, such as cool-storage boxes, bags, and iceboxes. Active refrigeration, such as freezers, is expensive, and controlling and reducing consumption and improving system efficiency are key challenges for researchers in this field. On the other hand, passive refrigeration, such as cool-storage boxes and phase-change materials, can utilize green electrical energy, such as solar energy or "valley" electrical energy, to store cold. Among other energy storage technologies, the use of solid-liquid transitions based on phase-change materials to store large amounts of energy has been implemented in various low-temperature applications, such as food storage, transportation, and air conditioning. Phase-change materials offer high energy storage densities and offer a compact and feasible solution to the supply-demand imbalance problem. Phase change materials are mainly divided into organic and inorganic phase change materials. Compared with inorganic phase change materials, organic phase change materials have advantages such as non-toxicity, slight supercooling, and good cycle stability, which have attracted more attention for practical application. However, organic phase change materials have a risk of leakage when used directly as energy storage materials, and encapsulation is essential to prevent leakage problems. In addition, the reprocessability and recyclability of organic phase change materials must also be considered to avoid environmental pollution and resource waste caused by organic phase change materials.

[0006] Therefore, the current technical challenges to be solved are how to provide a hydrophobic aerogel that not only has hydrophobic and water-resistant effects but also can be easily recycled in an environmentally friendly manner, and how to provide a recyclable cool-storing phase-change composite material based on the aerogel that has low leakage and is also recyclable.

[0007] [Contents of the invention] In view of the technical problems existing in the prior art, the present invention provides a recyclable polymer aerogel, as well as methods for its preparation, recycling, and use. This invention is the first to prepare aerogels from polymers containing maleimide group-containing structural units, thereby broadening the range of applications for copolymers containing maleic anhydride group-containing structural units and maleimide group-containing structural units. More importantly, the aerogels prepared in this invention have a very high recycling efficiency, potentially exceeding 99% after being dissolved in aqueous ammonia for recycling. The aerogel preparation and recycling process does not require the use of organic solvents, making it low-energy, highly efficient, and green and environmentally friendly. Furthermore, the polymer aerogels of the present invention have good hydrophobicity and water resistance, while also exhibiting low thermal conductivity, low density, and good heat resistance. Polymer aerogels can be used in many fields and have great application value.

[0008] Through research, the inventors have found that dissolving a polymer raw material containing maleic anhydride and its derivatives, such as a copolymer containing one or more of the following structural units: a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and ammonium salt group-containing structural unit, or a maleamic acid and ammonium salt group-containing structural unit, in aqueous ammonia yields an aqueous polymer solution. Freeze-drying followed by heat treatment yields a hydrophobic and water-resistant copolymer aerogel containing maleic anhydride and maleimide groups. The strong hydrogen bonds between the functional groups of maleic acid and its ammonium salt, maleamic acid and its ammonium salt, maleic anhydride, and maleimide stabilize the three-dimensional pore structure of the aerogel during the heat treatment process. Hydrophobic and water-resistant polymer aerogels can be obtained without crosslinking or hydrophobic treatment. This preparation method is green and environmentally friendly, reducing preparation time and material costs. The polymer aerogels prepared by this method can be recycled under the action of aqueous ammonia. The special properties of these polymers can be utilized to repeatedly convert water-soluble polymers into water-resistant hydrophobic aerogels. The above process does not require the use of organic solvents and is more environmentally friendly.

[0009] Based on the recyclable polymer aerogel, the present invention also provides a recyclable cold-storing phase-change composite material, its preparation method, and applications. The recyclable cold-storing phase-change composite material not only has cold-storing capacity, but can also be recycled and reused. At the same time, the recyclable cold-storing phase-change composite material is characterized by low leakage. Based on this, the present invention also provides a recyclable cold-storing phase-change material that not only has cold-storing capacity, recyclability, and low leakage, but also has real-time temperature monitoring capabilities.

[0010] A first aspect of the present invention is to provide a polymer aerogel, wherein the polymer comprises a maleic anhydride group-containing structural unit and a maleimide group-containing structural unit.

[0011] According to the present invention, the maleic anhydride group is [ka] The maleimide group refers to [ka] Refers to...

[0012] According to the present invention, the polymer is a carbon chain polymer in which heteroatoms O and N are present in pendant groups.

[0013] In a preferred embodiment of the present invention, the molar proportion of the maleimide group-containing structural units in the polymer is 5% to 70%, preferably 10% to 60%, and more preferably 20% to 50%, relative to the total molar amount of the maleic anhydride group-containing structural units and the maleimide group-containing structural units, which is 100%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any two numerical values ​​or any interval between any two numerical values.

[0014] According to the present invention, the polymer can be selected within a wide range, and in a preferred embodiment of the present invention, the polymer is derived from a polymeric raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units.

[0015] The maleic anhydride group is [ka] The maleimide group refers to [ka] The groups of maleic acid and its ammonium salts, and maleamic acid and its ammonium salts are [ka] The M's may be the same or different, and each M is hydroxyl, amino, or ammonium (-ONH4).

[0016] According to the present invention, the polymer is a carbon chain polymer in which heteroatoms O and N are present in pendant groups.

[0017] In the present invention, the polymer raw material includes, but is not limited to, a copolymer of an olefin monomer and a polymerizable monomer containing one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt. The present invention can also be achieved, for example, when the polymer raw material is a styrene-maleic anhydride-vinyl silicone oil copolymer. The copolymer of an olefin monomer and a polymerizable monomer containing one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt has lower raw material costs.

[0018] Preferably, the polymeric raw material is a copolymer of a polymerizable monomer including one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt with an olefinic monomer; more preferably, the olefinic monomer is at least one of α-methylstyrene, styrene, isobutylene, and vinyl acetate. More preferably, the polymeric raw material is an alternating copolymer of a polymerizable monomer including one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt with one of α-methylstyrene, styrene, and isobutylene.

[0019] For example, the polymer raw material in the present invention includes, but is not limited to, at least one of styrene-maleic anhydride copolymer, styrene-maleic anhydride-vinyl silicone oil copolymer, and maleic anhydride-isobutylene copolymer. Preferably, the polymer raw material in the present invention includes at least one of styrene-maleic anhydride copolymer and maleic anhydride-isobutylene copolymer.

[0020] In a preferred embodiment of the present invention, the polymer aerogel can be dissolved in aqueous ammonia at 0 to 150°C to form an aqueous polymer solution. Preferably, the aqueous polymer solution can be recycled by pre-freezing, freeze-drying, and heat treatment to obtain the polymer aerogel. Based on this, the polymer aerogel of the present invention can be easily recycled in an environmentally friendly manner.

[0021] In a preferred embodiment of the present invention, the polymer aerogel has a thermal conductivity of 0.025 to 0.05 W / (mk), preferably 0.027 to 0.04 W / (mk). The polymer aerogel of the present invention is characterized by its low thermal conductivity and can be used directly as a thermal insulating material without any treatment.

[0022] In a preferred embodiment of the present invention, the polymer aerogel has a viscosity of 10 to 100 kg / m 3 , preferably 15 to 75 kg / m 3 Specifically, for example, the density is 15 kg / m 3 , 35 kg / m 3 , 45 kg / m 3 , 55 kg / m 3 , 65 kg / m 3 , 75 kg / m 3and any two values ​​or any interval between any two values; and / or the polymer aerogel is a porous material. The polymer aerogel of the present invention has high porosity and is a three-dimensional porous material, and can be used as a carrier. For example, when used as a scaffold to support an organic phase-change material, the polymer aerogel can prevent leakage of the phase-change material, and the prepared phase-change composite can be recycled with aqueous ammonia.

[0023] As a result of research, the inventors of the present invention found that when the polymer aerogel is a styrene-maleic anhydride-maleimide copolymer aerogel, it also has photoluminescence properties and can change its optical signal with temperature changes. The photoluminescence properties of the polymer aerogel of the present invention can also be used to provide an indicator material that displays temperature changes.

[0024] In a preferred embodiment of the present invention, the polymer aerogel has a static water contact angle of 100° or greater, preferably 110° or greater, and more preferably 135° or greater.

[0025] In a preferred embodiment of the present invention, the polymer aerogel is insoluble in water. The polymer aerogel is preferably immersed in water at 20 to 40°C for 24 hours, preferably 72 hours, and more preferably 168 hours without dissolving, to form an aqueous solution of the polymer. The polymer aerogel of the present invention is characterized by its superoleophilic and hydrophobic properties, and can be used as an oil-water separation material without any further treatment.

[0026] In a preferred embodiment of the present invention, the polymer aerogel is prepared by reacting a polymer raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleic acid and its ammonium salt group-containing structural units with aqueous ammonia under sealed conditions, followed by pre-freezing, freeze-drying, and heat treatment for dehydration and deamination.

[0027] According to the present invention, the polymer aerogel may be an anisotropic aerogel or an isotropic aerogel.

[0028] The difference between anisotropic and isotropic aerogels is their pore structure. The pore structure of anisotropic aerogels exhibits long-range order, which is primarily due to the directional growth of ice crystals during the pre-freezing stage of the aerogel. During the growth process, impurities (polymers in this case) are expelled and accumulate to form pore walls. Subsequent freeze-drying, i.e., ice removal, yields porous aerogels. Therefore, anisotropic aerogels can be obtained by using a unidirectional cold source temperature during pre-freezing. There are many options for implementing this unidirectional cold source temperature, including, but not limited to, using liquid nitrogen as the low-temperature cold source during pre-freezing and placing a mold on a copper pillar immersed in liquid nitrogen, which allows ice crystals to grow upward from the bottom of the mold, ultimately forming an aerogel with an anisotropic pore structure.

[0029] Anisotropic aerogels are characterized by different pore structures, different axial and radial thermal conductivities, and different mass and sound transmission velocities. Anisotropic aerogels / isotropic aerogels can be selected depending on different application conditions. For example, the inventors of the present invention have found that when the phase change material of the present invention is encapsulated, the amount of leakage can be significantly reduced by using a preferred anisotropic aerogel, and there is no requirement for the direction of the anisotropic aerogel.

[0030] A second aspect of the present invention is to provide a method for preparing a polymer aerogel, comprising reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under sealed conditions, followed by pre-freezing, freeze-drying, and heat treatment for dehydration and deamination to obtain a polymer aerogel.

[0031] The aerogel preparation method of the present invention requires only heat treatment of water-soluble aerogel, avoiding the need for crosslinking agents or hydrophobic treatments, to produce hydrophobic and water-resistant aerogels. This preparation method is simple, straightforward, green, and environmentally friendly, and is suitable for preparing various maleimide copolymer aerogels. The aerogel preparation method of the present invention does not require the addition of a crosslinking agent.

[0032] In a preferred embodiment of the present invention, the preparation method comprises: (1) a step of reacting a polymer raw material with aqueous ammonia under a sealed condition to obtain an aqueous polymer solution; (2) pre-freezing the aqueous polymer 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 a polymer aerogel.

[0033] According to the present invention, the amounts of the polymer raw material, aqueous ammonia, etc. in step (1) can be selected within wide ranges. In a preferred embodiment of the present invention, in step (1), the mass fraction of the polymer raw material is 0.1% to 30%, preferably 0.5% to 10%, and more preferably 1% to 5%, of the total mass of the reaction system being 100%; the mass fraction of ammonia in aqueous ammonia is 0% to 30%, preferably 0.01% to 10%, and more preferably 0.1% to 1%, with the remainder being water.

[0034] According to the present invention, the reaction conditions in step (1) may be selected from a wide range, and in a preferred embodiment of the present invention, the reaction conditions include a reaction temperature of 0 to 200°C, preferably 50 to 150°C, more preferably 80 to 100°C, and / or a reaction time of 0.01 to 100 hours, preferably 0.5 to 10 hours, more preferably 1 to 5 hours. The reaction pressure is not particularly limited, and the reaction is preferably carried out under normal pressure.

[0035] In a preferred embodiment of the present invention, in step (2), the aqueous polymer solution obtained in step (1) is pre-frozen in a mold to obtain an ice block. The mold can be of any shape and size and can be customized depending on the desired aerogel. Freezing can be performed using a cold source such as a refrigerator or liquid nitrogen.

[0036] The cold source temperature in various directions of the aqueous solution during pre-freezing can be the same or different. The prepared aerogel is isotropic if the cold source temperature in various directions of the mixed solution during pre-freezing is constant. However, anisotropic aerogel can be prepared by using different cold source temperatures in various directions of the mixed solution during pre-freezing. Preferably, anisotropic aerogel is obtained by using different cold source temperatures in one direction during pre-freezing. There are many options for implementing the unidirectional cold source temperature, including, but not limited to, using liquid nitrogen as a low-temperature cold source during pre-freezing and growing ice crystals upward from the bottom of the mold by placing a mold on a copper pillar immersed in liquid nitrogen.

[0037] Specifically, the pre-freezing conditions may be temperature conditions commonly used in the art, and are not particularly limited in the present invention.

[0038] According to the present invention, the freeze-drying conditions may be selected within a wide range and are not particularly limited in the present invention. In a preferred embodiment of the present invention, the freeze-drying conditions include a temperature of -10°C or lower, for example, -20°C or lower, or -30°C or lower. According to the present invention, the vacuum degree for freeze-drying may be selected within a wide range. In a preferred embodiment of the present invention, the vacuum degree is 1000 Pa or lower, for example, 100 Pa or lower, or 10 Pa or lower. The freeze-drying conditions can be flexibly selected according to cost, efficiency, and the conventional operating method of the device.

[0039] The freeze-drying process may be carried out using a variety of freeze-drying equipment in the prior art, such as freeze dryers, freeze spray dryers, industrial freeze dryers, etc.

[0040] According to the present invention, the heat treatment conditions in step (3) can be selected from a wide range, and in a preferred embodiment of the present invention, the heat treatment conditions in step (3) include a temperature of 100 to 300°C, preferably 130 to 200°C, more preferably 150 to 190°C, and / or a time of 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours.

[0041] In a preferred embodiment of the present invention, the polymeric raw material can be reacted with aqueous ammonia to obtain a water-soluble polymer.

[0042] According to the present invention, the polymeric raw material can be selected from a wide range, and in a preferred embodiment of the present invention, the polymeric raw material is a polymer containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units. Preferably, the polymeric raw material is a copolymer of a polymerizable monomer containing one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt with an olefin monomer; more preferably, the olefin monomer comprises at least one of α-methylstyrene, styrene, and isobutylene.

[0043] For example, the polymer raw material in the present invention includes, but is not limited to, at least one of styrene-maleic anhydride copolymer, styrene-maleic anhydride-vinyl silicone oil copolymer, and maleic anhydride-isobutylene copolymer. Preferably, the polymer raw material in the present invention includes at least one of styrene-maleic anhydride copolymer and maleic anhydride-isobutylene copolymer.

[0044] More specifically, the method for preparing a polymer aerogel in the present invention includes the following steps: (a) reacting a polymer raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units with ammonia water under sealed conditions and heating to obtain an aqueous polymer solution; (b) pouring the aqueous polymer solution into a mold, pre-freezing it, and completely freezing it into ice blocks, and then placing the resulting ice blocks in a freeze dryer for freeze-drying for a certain period of time to obtain a water-soluble polymer; and (c) heat-treating the water-soluble polymer under constant temperature conditions to dehydrate and deaminate it, thereby obtaining a water-resistant maleimide-based aerogel.

[0045] The above polymeric raw materials are all polymers disclosed in the prior art and can be commercially obtained from the prior art or prepared according to the methods disclosed in the prior art.

[0046] In the present invention, the material of the sealed container is not particularly limited, and the container can be made of metal, non-metal, polymer, or other material.

[0047] As used herein, the term "and / or" means that the two conditions before and after "and / or" can be selected alternately or in combination.

[0048] A third aspect of the present invention provides a method for recycling polymer aerogel, the polymer aerogel being the polymer aerogel described in the first aspect or prepared by the preparation method described in the second aspect. The recycling method includes mixing and reacting the polymer aerogel and / or a material containing the polymer aerogel with aqueous ammonia under sealed conditions until an aqueous solution containing the recycled polymer is obtained, and optionally removing insoluble materials to obtain an aqueous solution of the recycled polymer. This aerogel recycling method does not require the introduction of organic solvents or high-temperature, high-pressure stirring treatments; it only requires a constant concentration of aqueous ammonia, preferably maintained at temperatures below 100°C, making it possible to achieve rapid and efficient recycling. This method is characterized by low energy consumption, low pollution, and high efficiency. The recycled polymer solution can be reused to prepare polymer aerogel.

[0049] The method for recycling polymer aerogel in the present invention includes the steps of adding polymer aerogel to ammonia water of a certain concentration, placing the resultant in a sealed container, and heating the resultant at a certain temperature to completely dissolve the polymer aerogel and obtain an aqueous solution of the copolymer.

[0050] According to the present invention, the mixing reaction conditions in the recycling method can be selected from a wide range, and in a preferred embodiment of the present invention, the mixing reaction temperature is 0 to 200°C, preferably 50 to 150°C, more preferably 80 to 100°C, and / or the mixing reaction time is 0.01 to 100 hours, preferably 0.5 to 10 hours, more preferably 1 to 5 hours. The reaction pressure is not particularly limited, and the reaction is preferably carried out under normal pressure.

[0051] In a preferred embodiment of the present invention, the recycling method also includes recycling the aqueous solution of the recycled polymer by pre-freezing, freeze-drying, and heat treatment to obtain a polymer aerogel.

[0052] According to the present invention, the cold source temperature in various directions of the aqueous solution during prefreezing can be the same or different. The prepared aerogel is isotropic if the cold source temperature in various directions of the aqueous solution during prefreezing is constant. However, anisotropic aerogel can be prepared if the cold source temperature in various directions of the aqueous solution during prefreezing is different. Preferably, anisotropic aerogel is obtained by varying the cold source temperature in one direction during prefreezing. There are many options for implementing the unidirectional cold source temperature, including, but not limited to, using liquid nitrogen as a low-temperature cold source during prefreezing and placing a mold on a copper pillar immersed in liquid nitrogen to allow ice crystals to grow upward from the bottom of the mold.

[0053] According to the present invention, the freeze-drying conditions can be selected within a wide range and are not particularly limited in the present invention. In a preferred embodiment of the present invention, the freeze-drying conditions include a temperature of −10° C. or lower, for example, −20° C. or lower, or −30° C. or lower, and / or a vacuum of 1000 Pa or lower, for example, 100 Pa or lower, or 10 Pa or lower.

[0054] According to the present invention, the heat treatment conditions can be selected within a wide range, and in a preferred embodiment of the present invention, the heat treatment conditions include a temperature of 100 to 300°C, preferably 130 to 200°C, more preferably 150 to 190°C, and / or a time of 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours.

[0055] A fourth aspect of the present invention provides a recycled polymer aerogel obtained by the recycling method according to the third aspect.

[0056] The polymer aerogel obtained by the above method has the same performance as the initially prepared polymer aerogel and can be recycled and reused.

[0057] A fifth aspect of the present invention provides use of the polymer aerogel according to the first aspect, the polymer aerogel prepared by the preparation method according to the second aspect, or the recycled polymer aerogel according to the fourth aspect as a porous material for adsorbing an organic phase-change material, preferably as a carrier, a filter material, an oil-water separation material, or a thermal insulation material. When used as a porous material, the polymer aerogel can be used as a carrier for supporting the phase-change material to prevent leakage of the phase-change material.

[0058] The hydrophobic polymer aerogel of the present invention can be directly used for oil-water separation, heat insulation, and thermal insulation without surface treatment, and can also be mixed with other components to prepare multi-component aerogels. If the other components are not soluble in ammonia water, the multi-component aerogel can be recycled with ammonia water.

[0059] A sixth aspect of the present invention provides a recyclable heat-storing phase-change composite material comprising a polymer aerogel and a phase-change material carried in the polymer aerogel, wherein the polymer aerogel is the polymer aerogel according to the first aspect, the polymer aerogel prepared by the preparation method according to the second aspect, or the recycled polymer aerogel according to the fourth aspect.

[0060] According to the present invention, the amounts of the phase change material and the polymer aerogel in the recyclable heat-storing phase change composite can be selected within a wide range. In a preferred embodiment of the present invention, the amount of the polymer aerogel is 2% to 20%, preferably 4% to 10%, such as 4%, 5%, 6%, 7%, 8%, 9%, 10%, and any two values ​​or any interval between any two values, and the amount of the phase change material is 80% to 98%, preferably 90% to 96%, based on the total mass of the recyclable heat-storing phase change composite being 100%.

[0061] Preferably, the total mass of the polymer aerogel and the phase change material is 100%.

[0062] 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, an organic phase change material. Preferably, the organic phase change material has a phase change temperature of (-10) to 30°C and / or a phase change latent heat of 55 to 280 J / g. More preferably, the organic phase change material is an alkane organic phase change material, and even more preferably, at least one of decane, dodecane, and tetradecane.

[0063] In a preferred embodiment of the present invention, the leakage amount of the phase change material in the recyclable heat-storing phase change composite material is less than 10 wt%, preferably less than 5 wt%, more preferably less than 2 wt% under temperature conditions in which the phase change material is in a liquid state.

[0064] According to the present invention, the polymer aerogel in the recyclable heat-storing phase change composite material may be anisotropic or isotropic aerogel.

[0065] The difference between anisotropic and isotropic aerogels is their pore structure. The pore structure of anisotropic aerogels exhibits long-range order, which is primarily due to the directional growth of ice crystals during the pre-freezing stage of the aerogel. During the growth process, impurities (polymers in this case) are expelled and accumulate to form pore walls. Subsequent freeze-drying, i.e., ice removal, yields porous aerogels. Therefore, anisotropic aerogels can be obtained by using a unidirectional cold source temperature during pre-freezing. There are many options for implementing this unidirectional cold source temperature, including, but not limited to, using liquid nitrogen as the low-temperature cold source during pre-freezing and placing the pre-freezing container on a copper column immersed in liquid nitrogen. This allows ice crystals to grow upward from the bottom of the pre-freezing container, ultimately forming an aerogel with an anisotropic pore structure.

[0066] Anisotropic aerogels are characterized by different pore structures, different axial and radial thermal conductivities, and different mass and sound transmission velocities. Anisotropic aerogels / isotropic aerogels can be selected depending on different application conditions. For example, the inventors of the present invention have found that when the phase change material of the present invention is encapsulated, the amount of leakage can be significantly reduced by using a preferred anisotropic aerogel, and there is no requirement for the direction of the anisotropic aerogel.

[0067] In a preferred embodiment of the present invention, the polymer aerogel in the recyclable heat-storing phase-change composite is an anisotropic aerogel, preferably obtained by using a different low-temperature source temperature in one direction during pre-freezing, which results in a lower leakage of the phase-change material in the recyclable heat-storing phase-change composite under temperature conditions where the phase-change material is in a liquid state.

[0068] In a preferred embodiment of the present invention, the polymer aerogel can be dissolved in aqueous ammonia at 0 to 150°C to form a solution containing the polymer. Preferably, the solution containing the polymer can be recycled by pre-freezing, freeze-drying, and heat treatment to obtain the polymer aerogel.

[0069] In a preferred embodiment of the present invention, the polymer aerogel has a thermal conductivity of 0.05 W / (mk) or less, preferably 0.04 W / (mk) or less. Because of its low thermal conductivity, the polymer aerogel of the present invention can be used directly as a thermal insulating material without any further treatment.

[0070] In a preferred embodiment of the present invention, the density of the polymer aerogel is 100 kg / m 3 or less, preferably 10 to 100 kg / m 3 , preferably 15 to 80 kg / m 3 , specifically, for example, 15 kg / m 3 , 35 kg / m 3 , 45 kg / m 3 , 55 kg / m 3, 65 kg / m 3 , 75 kg / m 3 , 80 kg / m 3 and any two values ​​or any interval between any two values; and / or the polymer aerogel is a porous material. The polymer aerogel of the present invention has high porosity and is a porous material, and can be used as a carrier. For example, when used as a scaffold to support an organic phase-change material, the polymer aerogel can prevent leakage of the phase-change material, and the prepared phase-change composite can be recycled with aqueous ammonia.

[0071] In a preferred embodiment of the present invention, the molar proportion of the maleimide group-containing structural units in the polymer is 5% to 70%, preferably 10% to 60%, and more preferably 20% to 50%, relative to the total molar amount of the maleic anhydride group-containing structural units and the maleimide group-containing structural units, which is 100%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any two numerical values ​​or any interval between any two numerical values.

[0072] According to the present invention, the polymer can be selected within a wide range, and in a preferred embodiment of the present invention, the polymer is derived from a polymeric raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units.

[0073] The maleic anhydride group is [ka] The maleimide group refers to [ka] The groups of maleic acid and its ammonium salts, and maleamic acid and its ammonium salts are [ka] The M's may be the same or different, and each M is hydroxyl, amino, or ammonium (-ONH4).

[0074] According to the present invention, the polymer is a carbon chain polymer in which heteroatoms O and N are present in pendant groups.

[0075] Preferably, the polymer raw material is a copolymer of a polymerizable monomer including one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt, and an olefin monomer; more preferably, the olefin monomer is at least one of α-methylstyrene, styrene, and isobutylene.

[0076] In a preferred embodiment of the present invention, the polymer aerogel can be dissolved in aqueous ammonia at 0 to 150°C to form a polymer-containing solution. Preferably, the polymer-containing solution can be recycled by pre-freezing, freeze-drying, and heat treatment to obtain a polymer aerogel. Based on this, the polymer aerogel of the present invention can be easily recycled in an environmentally friendly manner.

[0077] In a preferred embodiment of the present invention, the polymer aerogel has photoluminescence properties and can change its optical signal with temperature changes. The photoluminescence properties of the polymer aerogel in the present invention can also be utilized to provide an indicator material for indicating temperature changes.

[0078] In a preferred embodiment of the present invention, the polymer aerogel has a static water contact angle of 100° or greater, preferably 110° or greater, and more preferably 135° or greater. In a preferred embodiment of the present invention, the polymer aerogel is insoluble in water. Preferably, the polymer aerogel is immersed in water at 20 to 40°C for 24 hours, preferably 72 hours, and more preferably 168 hours without dissolving, to form an aqueous polymer solution. The polymer aerogel of the present invention is characterized by superoleophilicity and hydrophobicity, and can be used directly as an oil-water separation material without any further treatment.

[0079] In a preferred embodiment of the present invention, the method for preparing a polymer aerogel comprises reacting a polymer raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units with aqueous ammonia under sealed conditions, followed by pre-freezing, freeze-drying, and heat treatment for dehydration and deamination to obtain a polymer aerogel.

[0080] The aerogel preparation method of the present invention requires only heat treatment of water-soluble aerogel, avoiding the need for crosslinking agents or hydrophobic treatments, and can produce hydrophobic and water-resistant aerogels. This preparation method is simple, easy, green, and environmentally friendly, and is suitable for preparing various maleimide copolymer aerogels. The aerogel preparation method of the present invention does not require the addition of a crosslinking agent.

[0081] A seventh aspect of the present invention provides a method for preparing the recyclable heat-storing phase-change composite material according to the sixth aspect, the method comprising loading a phase-change material into a polymer aerogel; preferably, the method comprises first preparing the polymer aerogel and then loading the phase-change material into the polymer aerogel.

[0082] The method of loading the phase change material into the polymer aerogel can be various loading methods in the prior art. Specifically, the phase change material can be loaded by filling and injecting the phase change material in a liquid state, so that the phase change material is adsorbed and / or permeated into the composite aerogel.

[0083] The method for preparing the polymer aerogel includes reacting a polymer raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units with aqueous ammonia under sealed conditions, followed by pre-freezing, freeze-drying, and heat treatment for dehydration and deamination to obtain the polymer aerogel.

[0084] The method for preparing aerogels of the present invention requires only heat treatment of water-soluble aerogels, avoiding the need for crosslinking agents or hydrophobic treatments, and can produce hydrophobic and water-resistant aerogels. This preparation method is simple, straightforward, green, and environmentally friendly, and is suitable for preparing a variety of maleimide copolymer aerogels.

[0085] In a preferred embodiment of the present invention, the preparation method includes the steps of: (1) reacting a polymer raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units with ammonia water under sealed conditions to obtain an aqueous polymer solution; (2) pre-freezing the aqueous polymer 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 a polymer aerogel; and (4) loading a phase-change material into the polymer aerogel.

[0086] According to the present invention, the amounts of the polymer raw material, aqueous ammonia, etc. in step (1) can be selected within wide ranges. In a preferred embodiment of the present invention, in step (1), the mass fraction of the polymer raw material is 0.1% to 30%, preferably 1% to 10%, and more preferably 2% to 5%, of the total mass of the reaction system being 100%; the mass fraction of ammonia in the raw material, based on the mass of ammonia in aqueous ammonia, is 0.001% to 30%, preferably 0.01% to 10%, and more preferably 0.1% to 1%, with the remainder being water.

[0087] According to the present invention, the reaction conditions in step (1) may be selected from a wide range, and in a preferred embodiment of the present invention, the reaction conditions include a reaction temperature of 0 to 200°C, preferably 50 to 150°C, more preferably 80 to 100°C, and / or a reaction time of 0.01 to 100 hours, preferably 0.5 to 10 hours, more preferably 1 to 5 hours.

[0088] In a preferred embodiment of the present invention, in step (2), the aqueous polymer solution obtained in step (1) is pre-frozen in a pre-freezing container to obtain an ice block. The pre-freezing container can be of any shape and size and can be customized according to the desired aerogel. Freezing can be performed using a cold source such as a refrigerator or liquid nitrogen. The prepared aerogel is isotropic if the cold source temperature is constant in various directions in the pre-freezing container in this step. However, anisotropic aerogel can be prepared by varying the cold source temperature in various directions in the pre-freezing container. Preferably, anisotropic aerogel is obtained by varying the cold source temperature in one direction during pre-freezing. There are many options for implementing the unidirectional cold source temperature, including, but not limited to, using liquid nitrogen as a low-temperature cold source during pre-freezing and placing the pre-freezing container on a copper pillar immersed in liquid nitrogen to grow ice crystals upward from the bottom of the pre-freezing container.

[0089] Specifically, the pre-freezing conditions may be temperature conditions commonly used in the art, and are not particularly limited in the present invention as long as the aqueous polymer solution freezes.

[0090] According to the present invention, the freeze-drying conditions may be selected within a wide range and are not particularly limited in the present invention. In a preferred embodiment of the present invention, the freeze-drying conditions include a temperature of -10°C or lower, for example, -20°C or lower, or -30°C or lower. According to the present invention, the vacuum degree for freeze-drying may be selected within a wide range. In a preferred embodiment of the present invention, the vacuum degree is 1000 Pa or lower, for example, 100 Pa or lower, or 10 Pa or lower. The freeze-drying conditions can be flexibly selected according to cost, efficiency, and the conventional operating method of the device.

[0091] The freeze-drying process may be carried out using a variety of freeze-drying equipment in the prior art, such as freeze dryers, freeze spray dryers, industrial freeze dryers, etc.

[0092] According to the present invention, the heat treatment conditions in step (3) can be selected from a wide range, and in a preferred embodiment of the present invention, the heat treatment conditions in step (3) include a temperature of 100 to 300°C, preferably 130 to 200°C, more preferably 150 to 190°C, and / or a time of 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours. The reaction pressure is not particularly limited, and the reaction is preferably carried out under normal pressure.

[0093] According to the present invention, the polymeric raw material can be selected from a wide range, and in a preferred embodiment of the present invention, the polymeric raw material is a polymer containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units. Preferably, the polymeric raw material is a copolymer of a polymerizable monomer containing one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt with an olefin monomer; more preferably, the olefin monomer comprises at least one of α-methylstyrene, styrene, isobutylene, and vinyl acetate.

[0094] By way of example, the polymeric material may include, but is not limited to, at least one of styrene-maleic anhydride copolymer, methylstyrene-maleic anhydride copolymer, and maleic anhydride-isobutylene copolymer.

[0095] The above polymeric raw materials are all polymers disclosed in the prior art and can be commercially obtained from the prior art or prepared according to methods disclosed in the prior art.

[0096] In the present invention, the material of the sealed container is not particularly limited, and the container can be made of metal, non-metal, polymer, or other material.

[0097] More specifically, the method for preparing a polymer aerogel in the present invention includes the following steps: (a) reacting a polymer raw material containing one or more of maleic anhydride group-containing structural units, maleimide group-containing structural units, maleic acid and its ammonium salt group-containing structural units, and maleamic acid and its ammonium salt group-containing structural units with ammonia water under sealed conditions and heating to prepare an aqueous polymer solution; (b) pouring the aqueous polymer solution into a pre-freezing container, pre-freezing it, and completely freezing it into ice blocks, and then placing the resulting ice blocks in a freeze dryer for freeze-drying for a certain period of time to obtain a water-soluble polymer; and (c) subjecting the water-soluble polymer to heat treatment under constant temperature conditions to dehydrate and deaminate it, thereby obtaining a water-resistant maleimide-based aerogel.

[0098] The cold source temperatures in different directions of the solution during pre-freezing can be the same or different. More preferably, the cold source temperatures in different directions of the solution during pre-freezing can be different to obtain an anisotropic aerogel; most preferably, the cold source temperatures in one direction of the solution during pre-freezing can be different to obtain an anisotropic aerogel.

[0099] In a preferred embodiment of the present invention, in the pre-freezing step, the aqueous polymer solution obtained in step (1) is subjected to different cold source temperatures in various directions, preferably different cold source temperatures in one direction.

[0100] In a more preferred embodiment of the present invention, prior to pre-freezing in step (2), a mold is inserted into the aqueous polymer solution obtained in step (1), and the mold can be inserted so as to contact the bottom of the pre-freezing container or can be spaced apart 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 having cavities. In step (4), a phase-change material is supported in the polymer aerogel. This allows the storage object to be placed in the cavities remaining after removing the mold, facilitating storage.

[0101] When the mold of the present invention has a hollow structure, the object to be stored can be placed in the cavity of the mold without removing the mold during use. At the same time, by placing the object to be refrigerated (vaccine, medicine, etc.) in the cavity, the cold storage environment for the object to be refrigerated becomes more uniform, thereby improving the preservation effect.

[0102] The selection of the mold is not particularly limited, and the material of the mold may be glass, plastic, metal, etc. The mold may be solid or may have a hollow structure, and its shape is not particularly limited, and may preferably be cylindrical, columnar, etc. As for the structure, if the mold is to be removed, the mold may be solid or may have a hollow structure, and if the mold is not to be removed, the mold preferably has a hollow structure with an openable top. The size of the mold may be adjusted depending on the size of the object to be stored, and is not particularly limited in the present invention.

[0103] As used herein, the term "and / or" means that the two conditions before and after "and / or" can be selected alternately or in combination.

[0104] Real-time temperature monitoring of phase-change materials is also important. For example, most vaccines, including COVID-19 vaccines, must be kept below 8°C during transportation and storage, necessitating real-time temperature monitoring of each vaccine. It is also necessary to consider the reprocessability and recyclability of organic phase-change materials to avoid environmental pollution and resource waste caused by organic phase-change materials.

[0105] In view of the above technical problems, an eighth aspect of the present invention provides a recyclable heat-storing phase-change material with a real-time temperature monitoring function, the recyclable heat-storing phase-change material having a layer structure including an inner layer formed of the recyclable heat-storing phase-change composite material according to the sixth aspect or the recyclable heat-storing phase-change composite material prepared by the preparation method according to the seventh aspect, and an outer layer formed of a second polymer aerogel.

[0106] 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, and 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.

[0107] In a preferred embodiment of the present invention, a spacer layer is further disposed between the inner layer and the outer layer. In the present invention, the material of the spacer layer is not particularly limited as long as it can isolate the phase-change material encapsulated with aerogel from the outer aerogel to prevent mutual penetration. Such materials include, but are not limited to, metals (e.g., aluminum foil), plastics, etc.

[0108] The thickness of the inner layer can be controlled during the preparation process by adjusting the distance of the four walls from the spacer layer or the distance between the four walls and the bottom of the mold, and the thickness of the outer layer can be controlled by adjusting the distance of the periphery of the spacer layer from the wall of the outer container.

[0109] The recyclable heat-storing phase-change material may be cylindrical with a radial layer structure, with an outer layer formed by the second polymer aerogel and an inner layer formed by the recyclable heat-storing phase-change composite, with a spacer layer disposed between the two layers. Alternatively, the recyclable heat-storing phase-change material may be flat with a layer structure, with the middle layer being a spacer layer, with an outer layer formed by the second polymer aerogel on one side of the spacer layer and an inner layer formed by the recyclable heat-storing phase-change composite on the other side. Preferably, the recyclable heat-storing phase-change material is also wrapped on the outermost side with a sealing material. In the present invention, the shape and structure of the spacer layer are not particularly limited. For example, the spacer layer may be cylindrical or flat, as long as it can be wrapped around the outer aerogel of the inner layer to separate the inner and outer layers.

[0110] Preferably, the inner layer has a cavity formed from the mold itself or from a cavity formed after the mold is removed. In use, an object to be refrigerated (e.g., a vaccine, a medicine, etc.) can be placed in the cavity, which makes the cooling environment in which the object to be refrigerated is placed more uniform and improves the preservation effect.

[0111] According to the present invention, the second polymer aerogel can be selected from a wide range of materials, and preferably, the second polymer aerogel has photoluminescence (i.e., fluorescence) properties and can change its optical signal with temperature. In this specification, the optical signal refers to the peak position and / or intensity in the fluorescence spectrum.

[0112] In a preferred embodiment of the present invention, the second polymer aerogel is selected from at least one of the polymer aerogels in the recyclable heat-storing phase-change composite described in the sixth embodiment, which have photoluminescence (i.e., fluorescence) properties and can change their optical signal with temperature changes; and the second polymer aerogel and the polymer aerogel in the recyclable heat-storing phase-change composite may be the same or different. More preferably, the second polymer is a styrene-maleic anhydride-maleimide copolymer (i.e., a copolymer formed from styrene and a polymerizable monomer containing one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt). The inventors have found that styrene-maleic anhydride-maleimide copolymer aerogels have fluorescence properties, which change their optical signal with temperature changes.

[0113] For example, in a specific embodiment of the present invention, the cool-storing phase-change material of the present invention is characterized in that an inner layer is formed of the aerogel phase-change composite material according to the sixth aspect, and an outer layer is formed of the polymer aerogel used in the aerogel phase-change composite material according to the sixth aspect. Preferably, the aerogel has a photoluminescence effect (for example, the aerogel may be a styrene-maleic anhydride / maleimide copolymer aerogel), and the intensity of the photoluminescence changes with temperature (for example, the intensity increases as the temperature decreases). Therefore, the temperature of the phase-change material can be determined by measuring the fluorescence intensity, and real-time temperature monitoring of the cool-storing material can be realized.

[0114] A ninth aspect of the present invention is a method for preparing a recyclable cold storage phase change material with real-time temperature monitoring function according to the eighth aspect, comprising: (1) a step of reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under a sealed condition to obtain an aqueous polymer solution; (2) disposing the polymer aqueous solution in the space inside the spacer layer or in the space between the inside of the spacer layer and the mold, and then pre-freezing and freeze-drying the solution to obtain a water-soluble polymer (i.e., a polymer aerogel precursor); (3) heat-treating the water-soluble polymer obtained in step (2) and optionally removing it from the mold to obtain a polymer aerogel having voids; (4) forming an inner layer of a recyclable heat-storing phase-change material by loading a phase-change material into the polymer aerogel obtained in step (3); During and / or between steps (2), (3), and (4), and / or after step (4), a second polymer aerogel is wrapped around the outside of the spacer layer to form an outer layer of recyclable heat-storing phase-change material; or, In step (2), the aqueous solution containing the second polymer aerogel and / or the second aqueous polymer solution is placed in the space outside the spacer layer to form an outer layer of the recyclable heat-storing phase-change material; preferably, the second aqueous polymer solution is the same as the aqueous polymer solution in step (1); That is, step (2) is preferably carried out as follows: An aqueous polymer 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 having a layer structure.

[0115] According to the above technical solution, the method for preparing a recyclable heat-storing phase-change material with real-time temperature monitoring function of the present invention includes a polymer aerogel preparation process, in which the polymer aerogel disposed inside the spacer layer can be obtained using the above-mentioned method for preparing a polymer aerogel (recyclable polymer aerogel). Simultaneously, during the preparation process of the polymer aerogel for the inner layer, a second polymer aerogel or an aqueous solution containing the second polymer aerogel and / or an aqueous solution of the second polymer is wrapped around the outside of the spacer layer. The timing of wrapping the second polymer aerogel or the aqueous solution containing the second polymer aerogel and / or the aqueous solution of the second polymer around the outside of the spacer layer can be selected depending on the type of second polymer aerogel used. For example, if the second polymer aerogel is the same type as the polymer aerogel in the inner layer, the water-soluble polymer obtained in step (1) can be placed on the outside of the spacer layer in step (2). By carrying out subsequent processing steps, a recyclable polymer aerogel can be placed on both the inside and outside of the spacer layer after step (3). If the second polymer aerogel (or precursor) does not require freeze-drying but does require heat treatment, the second polymer aerogel can also be placed on the outside of the spacer layer in step (2). If the second polymer aerogel (or precursor) does not require heat treatment, the finished second polymer aerogel can be placed on the outside of the spacer layer after steps (3) or (4). In other words, the process time can be flexibly adjusted based on the principle of procedure or process omission, depending on the type of second polymer aerogel.

[0116] Specifically, the amount of aerogel raw material in the inner and outer layers can be selected within a wide range, and it is preferable that the thickness of the inner layer is 3 mm or more and the thickness of the outer layer is 5 mm or more in the finished product.

[0117] The material selection of the second polymer aerogel or (precursor), the material selection and amount of the phase change material, etc. may be the same as those of the second polymer aerogel or (precursor), the material selection and amount of the phase change material described in the eighth embodiment, and will not be repeated here.

[0118] In a preferred embodiment of the present invention, the mass fraction of the polymer in the aqueous polymer solution of the inner layer is 0.1% to 30%, preferably 1% to 10%, more preferably 2% to 5%, and / or the mass fraction of the second polymer in the aqueous solution of the second polymer aerogel and / or the second polymer in the aqueous solution of the second polymer is 0.1% to 30%, preferably 0.5% to 10%, more preferably 1% to 5%, respectively.

[0119] In a preferred embodiment of the present invention, in step (2), the aqueous polymer solution obtained in step (1) is subjected to different cold source temperatures in various directions, preferably different cold source temperatures in one direction, during the pre-freezing stage. In this way, an anisotropic aerogel can be obtained. In this preferred embodiment, the resulting cold storage material has less leakage.

[0120] The shape and size of the prefreezing container can be arbitrary and can be customized depending on the required aerogel or the object to be refrigerated. Freezing can be performed using a cold source such as a refrigerator or liquid nitrogen. If the cold source temperature in various directions of the prefreezing container in this process is constant, the prepared aerogel will be isotropic. However, if the cold source temperature in various directions of the prefreezing container is different, an anisotropic aerogel can be prepared. In the present invention, an anisotropic aerogel is preferred, and an anisotropic aerogel obtained using a cold source temperature that varies in one direction is more preferred.

[0121] The specific conditions for (1), (2), and (3) above can all be selected within a wide range, and the conditions preferred in the above-mentioned method for preparing a polymer aerogel can be preferably adopted.

[0122] More specifically, the heat treatment temperature in step (3) is 100 to 300°C, preferably 120 to 220°C, more preferably 160 to 200°C, and the heat treatment time is 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours.

[0123] According to the present invention, a method for recycling the recyclable polymer aerogel in the above-mentioned recyclable heat-storing phase-change composite material can be provided as follows: This recycling method includes the steps of mixing and reacting polymer aerogel and / or a polymer aerogel-containing material with ammonia water under sealed conditions until an aqueous solution containing the recycled polymer is obtained, and optionally removing insoluble materials to obtain an aqueous solution of the recycled polymer. This aerogel recycling method does not require the introduction of organic solvents or high-temperature, high-pressure stirring treatments; it only requires a constant concentration of ammonia water maintained at a temperature preferably below 100°C, thereby enabling rapid and efficient recycling. This method is characterized by low energy consumption, low pollution, and high efficiency. The recycled polymer solution can be reused to prepare polymer aerogel.

[0124] The method for recycling polymer aerogel in the present invention includes the steps of adding polymer aerogel to ammonia water of a certain concentration, placing the resultant in a sealed container, and heating the mixture at a certain temperature to completely dissolve the polymer aerogel and obtain an aqueous solution of the copolymer.

[0125] According to the present invention, the mixing reaction conditions in the recycling method can be selected from a wide range, and in a preferred embodiment of the present invention, the mixing reaction temperature is 0 to 200°C, preferably 50 to 150°C, more preferably 80 to 100°C, and / or the mixing reaction time is 0.01 to 100 hours, preferably 0.5 to 10 hours, more preferably 1 to 5 hours.

[0126] In a preferred embodiment of the present invention, the recycling method also includes lyophilizing and heat-treating the aqueous solution of the recycled polymer to obtain a polymer aerogel. Preferably, the lyophilization conditions include a temperature of −10° C. or lower, e.g., −20° C. or lower, or −30° C. or lower, and / or a vacuum of 1000 Pa or lower, e.g., 100 Pa or lower, or 10 Pa or lower.

[0127] According to the present invention, the heat treatment conditions can be selected within a wide range, and in a preferred embodiment of the present invention, the heat treatment conditions include a temperature of 100 to 300°C, preferably 130 to 200°C, more preferably 150 to 190°C, and / or a time of 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours.

[0128] When recycling the recyclable polymer aerogel in the recyclable cold-storing phase change composite material and the recyclable cold-storing phase change material with real-time temperature monitoring function, the above-mentioned method can be adopted, which includes treating the recyclable cold-storing phase change composite material of the inner layer of the recyclable cold-storing phase change composite material or the recyclable cold-storing phase change material with real-time temperature monitoring function with ammonia water to separate the polymer from the phase change material, and then undergoing a post-treatment process to obtain the recyclable polymer aerogel, or the preparation method of the recyclable cold-storing phase change composite material or the recyclable cold-storing phase change material with real-time temperature monitoring function of the present invention can be reused to obtain the recyclable cold-storing phase change composite material or the recyclable cold-storing phase change material with real-time temperature monitoring function of the present invention.

[0129] When the second polymer aerogel is the recyclable polymer aerogel of the present invention (the polymer in the polymer aerogel contains maleic anhydride groups and maleimide groups), the second polymer aerogel can be recycled together with the material of the inner layer according to the above method; when the second polymer aerogel is a different type of polymer aerogel, the second polymer aerogel of the outer layer of the recyclable cool-storing phase-change material with real-time temperature monitoring function can be peeled off, and then the subsequent recycling process is carried out.

[0130] A tenth aspect of the present invention provides use of the recyclable cold-storing phase-change composite material according to the sixth aspect, or the recyclable cold-storing phase-change composite material prepared by the preparation method according to the seventh aspect, the recyclable cold-storing phase-change material with real-time temperature monitoring function according to the eighth aspect, or the recyclable cold-storing phase-change material with real-time temperature monitoring function prepared by the preparation method according to the ninth aspect, in the fields of food preservation and cold chain transportation.

[0131] According to the above technical solution, the present invention provides a recyclable polymer aerogel, and its preparation method, recycling method and use. The present invention also provides a recyclable cold-storing phase change composite material, a recyclable cold-storing phase change material with real-time temperature monitoring function, and its preparation method and use. Compared with the prior art, the present invention has the following advantages: The polymer aerogels of the present invention possess superoleophilic and hydrophobic properties without crosslinking or hydrophobic treatment, and can be used directly as oil-water separation materials without any further processing. They can also be recycled conveniently and environmentally, with a recycling rate of over 99%. The aerogel preparation and recycling method does not require the use of organic solvents, making them low-energy, highly efficient, green, and environmentally friendly. Furthermore, the polymer aerogels of the present invention have low thermal conductivity, low density, and good heat resistance, making them suitable for use in many fields and highly applicable. This invention is the first to produce aerogels using polymers containing maleimide groups, and copolymers containing maleic anhydride and maleimide groups have a wide range of applications.

[0132] The recyclable cold-storing phase-change composite material of the present invention includes a polymer aerogel and a phase-change material supported in the polymer aerogel, where the polymer in the polymer aerogel contains a maleic anhydride group-containing structural unit and a maleimide group-containing structural unit. The polymer aerogel can be recycled with aqueous ammonia and then post-treated (including thermal treatment) to obtain a recycled polymer aerogel, which can be reused. Based on this, the recyclable cold-storing phase-change composite material of the present invention can be repeatedly recycled and reused. The recyclable cold-storing phase-change composite material of the present invention is not only recyclable, but also has strong cold-storing performance, less leakage of phase-change material, and can maintain low temperatures for long periods of time. The recyclable cold-storing phase-change composite material of the present invention can be widely used in the fields of food preservation and cold chain transportation (such as cold chain transportation of vaccines and medicines).

[0133] Furthermore, the recyclable phase-change material with real-time temperature monitoring function of the present invention has a sandwich structure including an inner layer formed of a recyclable phase-change composite with a recyclable phase-change composite with a second polymer aerogel, thereby achieving better heat retention performance. Furthermore, if the second polymer aerogel has photoluminescence properties and can change its optical signal with temperature changes, better temperature monitoring can be achieved. In this way, large-scale temperature monitoring and recyclability can be simultaneously achieved.

[0134] [Figure description] FIG. 1 shows the Fourier transform infrared spectrum test curves of Comparative Example 3A, Example 1A and the aerogel recycled from Example 1A.

[0135] FIG. 2 shows the results of Example 1A and the aerogel recycled from Example 1A. 1 The H NMR spectrum curve is shown.

[0136] As can be seen from Figures 1 and 2, the Fourier spectrum (Figure 1) shows the peak at 3207 cm -1 and 3444 cm -1 There are prominent NH stretching vibration absorption peaks and hydrogen bond characteristic absorption peaks at 1780 cm, indicating the presence of amide groups. The peaks of the asymmetric and symmetric stretching vibrations of C=O of maleic anhydride are at 1780 cm. -1 and 1857 cm -1 Located at 1716cm -1 and 1662 cm -1 The absorption peaks at 935 cm indicate the presence of carboxyl and amide groups. The characteristic absorption peak of the anhydride five-membered ring COC is at 935 cm. -1 Located at 1349cm -1 The absorption peak is a peak of the C-N stretching vibration characteristic of the imide ring. 1In the H NMR spectrum (Figure 2), the chemical shifts of the five hydrogens on the benzene ring are between 7.7 ppm and 6.0 ppm, and the chemical shifts of the hydrogens on the NH of maleimide are between 10.2 ppm and 9.4 ppm. Using the hydrogens on the benzene ring as an internal standard, the ratio of maleimide to maleic anhydride (the amount of maleic anhydride in the polymer raw material is equal to the total amount of maleic anhydride and maleimide in the polymer aerogel) (maleimide ratio) can be calculated by the integrated areas of maleimide and the hydrogens on the benzene ring. In conclusion, the infrared spectrum test curve of the aerogel in Figure 1 and the aerogel in Figure 2 show that the ratio of maleimide to maleic anhydride (maleic anhydride in the polymer raw material is equal to the total amount of maleic anhydride and maleimide in the polymer aerogel) (maleimide ratio) can be calculated by the integrated areas of maleimide and the hydrogens on the benzene ring. 1 From the H NMR spectrum curve, it can be determined that maleimide structures exist in the aerogel structure.

[0137] FIG. 3 is a scanning electron micrograph of the pore structure of the aerogel obtained in Example 1A, which confirms the presence of a porous structure in the aerogel.

[0138] FIG. 4 shows the temperature rise curve of the heat-storing phase-change material obtained in Example 1B.

[0139] The test results in Figure 4 show that the prepared phase change material can maintain low temperatures for a long time.

[0140] FIG. 5 shows the emission spectrum at an excitation wavelength of 400 nm of the maleimide-based aerogel contained in the outer layer of the cold-storing phase-change material prepared in Example 1B.

[0141] Figure 5 shows that the fluorescence-temperature relationship of the surface aerogel allows the temperature of the phase-change material to be monitored in real time.

[0142] FIG. 6 is a schematic diagram showing the appearance of the recyclable heat-storing phase-change composite material (a), the recycled phase-change material (b), and the recycled polymer aerogel (c) in Recycling Example B, which shows that the recyclable heat-storing phase-change composite material of the present invention is recyclable.

[0143] FIG. 7 is a schematic diagram showing the three-dimensional structure of the aerogel phase-change heat storage material with real-time temperature monitoring function obtained in Example 1B.

[0144] FIG. 8 is a schematic diagram showing the longitudinal cross-sectional structure of the aerogel phase-change heat storage material having a real-time temperature monitoring function obtained in Example 1B.

[0145] 1 - outer layer, 2 - spacer layer, 3 - inner layer, 4 - cavity.

[0146] Detailed Description of Specific Embodiments The present invention will be specifically described below in conjunction with specific examples.It should be noted that the following examples are only used to further explain the present invention and cannot be understood as limiting the protection scope of the present invention.Some insubstantial improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0147] The experimental data in the examples was determined using the following instruments and methods.

[0148] (1. Aerogel water solubility test method) 1 g of aerogel was placed in 100 g of water and soaked at room temperature for 72 hours. After that, it was removed, dried, and its mass m1 was measured. When m1 was greater than 99%, the polymer aerogel was considered water-resistant. When the aerogel was completely dissolved in water, it was considered a water-soluble aerogel.

[0149] (2. Water contact angle test method for aerogel) The water contact angle of the product obtained in the examples was tested using an EASYDROP contact angle tester manufactured in Germany according to the following procedure: The polymer aerogel was cut into a thin blade of approximately 10 × 10 × 2 mm 3a process of cutting the aerogel sheet into sheets; a process of fixing the aerogel sheet on an operating table; a process of keeping the sample horizontally flat during the fixing process, and then a process of fixing a slide glass on the sample stage of the EASYDROP contact angle tester and dropping a water droplet onto the center of the sample, the volume of which is controlled by an adjustment device to be 4±0.02 μL; a process of dropping the water droplet on the surface of the aerogel for 1 minute, and then measuring the angle from the solid-liquid interface through the inside of the droplet to the gas-liquid interface of the three-phase interface, i.e., the water static contact angle (abbreviated as water contact angle).

[0150] (3. Testing Method for Thermal Conductivity of Aerogel) The thermal conductivity was tested using a TC3100 model hot wire universal thermal conductivity meter manufactured by Xi'an Xiaxi Electronic Technology Co., Ltd., according to the following steps: First, the aerogel was cut into approximately 30 × 20 × 5 mm pieces with a thin blade. 3 a process of cutting the aerogel into a sheet; a process of covering both sides of the test probe with two aerogel sheets; and a process of pressing firmly using a weight and then adjusting the test temperature to 25°C; and a process of setting the test method to insulation material sample test and determining the thermal conductivity, which is the average value of at least five test results.

[0151] (4. Characterization of Aerogel Structures by Fourier Transform Infrared Spectroscopy) The aerogels of the examples were tested using a Nicolet IS5 Fourier transform infrared spectrometer. The infrared spectra of the samples were collected by a KBr tableting method. In this method, an appropriate amount of aerogel was collected, crushed with KBr, and tableted. The number of scans was 32, the spectral collection range was 400-4000 cm, and the optical frequency was 1 cm. -1 The test was carried out under the following conditions.

[0152] (5. Aerogel Structure 1 H NMR Spectroscopic Characterization Example aerogel samples 1H NMR was tested using a 400-MR DD2 NMR spectrometer from Agilent, USA, where dimethyl sulfoxide-d6 was used as the solvent for water-soluble aerogels, acetone-d6 was used as the solvent for hydrophobic and water-resistant aerogels, and tetramethylsilane (TMS) was used as the internal standard.

[0153] (6. Pore structure testing method for aerogel) The pore structure of the example aerogel samples was observed using an EM30AX scanning electron microscope manufactured by COXEM Co., Ltd., Korea, according to the following steps: first, coating the surface of the test sample with gold; then placing the coated sample on the test stage of the scanning electron microscope; and finally, scanning an area on the sample using the scanning electron microscope to obtain a photograph of the pore structure.

[0154] (7. Test method for thermal stability of aerogel) The thermal stability of 5 mg of aerogel samples was tested by thermogravimetric analysis (TGA, Mettler Toledo, Switzerland) in a nitrogen atmosphere at a heating rate of 20°C / min over the temperature range of 50°C to 550°C.

[0155] (8. Glass Transition Temperature Test Method) The glass transition temperatures of the samples were measured using Perkin-Elmer's Pyris™, calibrated using indium and zinc standards. -1 Tests were performed using a differential scanning calorimeter (DSC). Five to six mg of sample was heated from 150 to 300 °C under a nitrogen stream from an injection rod and held at 300 °C for 3 minutes. The sample was then cooled to 150 °C, held for 1 minute, and heated again to 300 °C. All heating and cooling steps were program-controlled at a rate of 10 °C / min. The glass transition temperature (Tg) was determined from the relevant peak in the DSC curve.

[0156] (9. Leakage Amount Test Method) 15 g of the sample obtained in the examples was taken, and filter paper was placed on a heating table at 30°C. The sample was left upside down on the filter paper for 10 minutes, after which the sample was removed and weighed as m (g). The leakage amount was calculated as m / 15 x 100 wt%. If the sample was completely dissolved and could not be removed, the leakage amount was calculated as 100 wt%.

[0157] (10. Three-dimensional fluorescence spectroscopy) The fluorescence spectrum of the nano-fluorescent elastic particles was measured using an F-7000 FL spectrometer. The test method was wavelength scanning, with the excitation wavelength set at 400 nm, to measure the emission spectrum.

[0158] (11. Testing method for the cold storage capacity of phase change materials) 10 ml of ethanol was added to a 10 ml glass vial, which was then frozen to -30°C and placed in a thermostatic bath at 25°C. A thermocouple was inserted into the ethanol to evaluate the cooling effect.

[0159] (12. Testing Method for Adsorption Amount of Phase Change Materials) Before the test, the entire sample was weighed on a balance to determine m1. After the phase-change material was adsorbed, the sample was inverted, wiped, and excess phase-change material was removed from the surface. The weight of the entire sample was then measured to determine m2. The amount of adsorbed phase-change material was m2 - m1.

[0160] (13. Phase transition temperature test method) The thermal properties of aerogels and phase change materials were measured using Perkin-Elmer's Pyris™, calibrated using indium and zinc standards. -1 Tests were performed using a differential scanning calorimeter (DSC). For the aerogels, samples were heated from 20°C to 150°C under a nitrogen stream and held at 20°C and 150°C for 5 minutes. For the phase-change materials, samples were heated from 50°C to 300°C under a nitrogen stream and held at 50°C and 300°C for 5 minutes. All heating and cooling steps were performed at a program-controlled rate of 20°C / min. The latent heats of fusion (ΔHm) and solidification (ΔHf), as well as the melting temperature (Tm) and solidification temperature (Tf), were determined from the relevant peaks in the DSC curves.

[0161] The raw materials used in the examples are shown in Table 1.

[0162] [Table 1]

[0163] [Preparation Example 1A] 500 ml of isoamyl acetate was placed in a 1000 ml three-neck flask and charged with nitrogen to remove oxygen for 30 minutes. 24.5 g of maleic anhydride and 26 g of styrene were added to the flask. After complete dissolution, 0.4 g of azodiisobutyronitrile was added, and the water bath temperature was raised to 70°C and the reaction was allowed to proceed for 7 hours. After the reaction, the reaction solution was centrifuged at 10,000 r for 10 minutes, the supernatant was removed, 500 ml of methanol was added, and the mixture was stirred for 0.5 hours. This process of centrifuging and removing the supernatant was repeated twice. The reaction product was then vacuum dried at 140°C for 24 hours to obtain a styrene-maleic anhydride copolymer.

[0164] [Preparation example 2A] 500ml of isoamyl acetate was placed in a 1000ml three-neck flask and charged with nitrogen to remove oxygen for 30 minutes. 24.5g of maleic anhydride and 26.2g of styrene were added to the flask, and 3.69g of Dayi DY-V421 vinyl silicone oil was added dropwise. After complete dissolution, 0.4g of azodiisobutyronitrile was added, and the water bath temperature was raised to 70°C and the reaction was allowed to proceed for 7 hours. After the reaction, the reaction solution was centrifuged at 10,000 r for 10 minutes, the supernatant was removed, 500ml of methanol was added, and the mixture was stirred for 0.5 hours. This process of centrifuging and removing the supernatant was repeated twice. The reaction product was then vacuum dried at 140°C for 24 hours to obtain a styrene-maleic anhydride-vinyl silicone oil copolymer.

[0165] [Preparation example 3A] 91.5 g of water was added to a capped glass bottle, followed by 3.5 g of ammonia water with a mass fraction of 25% and 5 g of the maleic anhydride-styrene copolymer obtained in Preparation Example 1A. After tightly tightening the cap, the glass bottle was placed in an oven and held at 95°C for 4 hours, after which it was removed, yielding a homogeneous polymer solution with a mass fraction of 5%. This polymer solution was air-dried at room temperature to yield a polymer containing maleic acid groups and ammonium maleate groups.

[0166] Example 1A 91.5 g of water was added to a capped glass bottle, followed by 3.5 g of ammonia water (25% by mass) and 5 g of maleic anhydride-styrene copolymer. After the cap was tightly fastened, the glass bottle was placed in an oven and heated to 95°C for 4 hours. After that, a homogeneous polymer solution (5% by mass) was obtained.

[0167] This polymer solution was poured into six molds, 15 ml per mold, and frozen in a refrigerator at −30°C for 2 hours. The frozen samples were then transferred to a freeze dryer and freeze-dried (below −30°C, below 10 Pa) for 72 hours to obtain a water-soluble polymer.

[0168] This water-soluble polymer was placed in an incubator at 180° C. for 2 hours for dehydration and deamination, to obtain a maleimide-based aerogel (i.e., the polymer aerogel of the present invention).

[0169] [Comparative Example 1A] The preparation process was the same as in Example 1A, except that 91.5 g of water and 3.5 g of 25% mass fraction aqueous ammonia in Example 1A were replaced with 94 g of water and 1 g of sodium hydroxide.

[0170] [Comparative example 2A] The preparation process was the same as in Example 1A, except that 91.5 g of water and 3.5 g of 25% mass fraction aqueous ammonia in Example 1A were replaced with 94 g of water and 2 g of sodium hydroxide.

[0171] [Comparative example 3A] The preparation process was the same as in Example 1A, except that the heat treatment step of Example 1A was not performed.

[0172] [Comparative example 4A] The preparation process was the same as in Example 1A, except that the maleic anhydride in the maleic anhydride-styrene copolymer of Example 1A was replaced with N-phenylmaleimide.

[0173] Example 2A The preparation process was the same as in Example 1A, except that 91.5 g of water, 3.5 g of 25% mass fraction ammonia water, and 5 g of maleic anhydride-styrene copolymer in Example 1A were replaced with 94.9 g of water, 2.1 g of 25% mass fraction ammonia water, and 3 g of maleic anhydride-styrene copolymer.

[0174] Example 3A The preparation process was the same as in Example 1A, except that 91.5 g of water, 3.5 g of 25% mass fraction ammonia water, and 5 g of maleic anhydride-styrene copolymer in Example 1A were replaced with 98.3 g of water, 0.7 g of 25% mass fraction ammonia water, and 1 g of maleic anhydride-styrene copolymer.

[0175] Example 4A The preparation process was the same as in Example 1A, except that 5 g of maleic anhydride-styrene copolymer in Example 1A was replaced with 5 g of maleic anhydride-isobutylene copolymer (Kuraray ISOBAM-08).

[0176] Example 5A The preparation process was the same as in Example 1A, except that 5 g of the maleic anhydride-styrene copolymer in Example 1A was replaced with 5 g of the polymer obtained in Preparation Example 3A.

[0177] Example 6A The preparation process was the same as in Example 1A, except that the maleic anhydride copolymer of Example 1A was replaced with the styrene-maleic anhydride-vinyl silicone oil copolymer obtained in Preparation Example 2A.

[0178] Example 7A The preparation process was carried out in the same manner as in Example 5A, except that 3.5 g of aqueous ammonia having a mass fraction of 25% was replaced with 3.5 g of water, the glass bottle was replaced with a reaction kettle having a polytetrafluoroethylene inner tank, the temperature of the oven holding the glass bottle was changed from 95°C to 150°C, and the time for holding the glass bottle in the oven was changed from 4 hours to 12 hours, and the heat treatment temperature was changed to 130°C so as to obtain a uniform polymer solution having a mass fraction of 5%.

[0179] Example 8A According to the method of Example 5A, 3.5 g of ammonia water having a mass fraction of 25% and 91.5 g of water were replaced with 40 g of ammonia water having a mass fraction of 25% and 55 g of water, the temperature of the oven for holding the glass bottle was changed from 95°C to 20°C, and the time for holding the glass bottle in the oven was changed from 4 hours to 0.5 hours. Except for this, the preparation process was carried out in the same manner as in the method of Example 5A, and the heat treatment temperature in Example 1A was changed to 200°C.

[0180] [Test method for cycle efficiency of aerogel obtained in the examples and method for recycling aerogel (Recycling Example A)] The water-resistant maleimide-based aerogel of the present invention was weighed to a mass m1. 91.5 g of water was added to a sealed glass bottle with a cap, followed by 3.5 g of 25% mass fraction ammonia water and 5 g of water-resistant maleimide-based aerogel (i.e., m1). After tightly tightening the cap, the sealed glass bottle was placed in an oven and heated at 95°C for 2 hours to obtain a homogeneous recycled polymer solution. This polymer solution was poured into six molds, 15 ml per mold, and frozen in a refrigerator at -30°C for 2 hours. The frozen samples were then transferred to a freeze dryer and freeze-dried for 72 hours to obtain a recycled water-soluble polymer. This recycled water-soluble polymer was then placed in an incubator at 180°C for 2 hours to dehydrate and deaminate the water-resistant maleimide-based aerogel (i.e., the recycled polymer aerogel of the present invention).

[0181] The recycled water-resistant maleimide-based aerogel was weighed as mass m2, and the cycle efficiency was calculated as m2 / m1 × 100%.

[0182] Here, the performance of the water-resistant maleimide-based aerogel (polymer aerogel) of Example 1A after recycling is shown in Table 1A and Table 2A as Example 1A (Recycled 1), which is the sample name corresponding to Example 1A after one recycling, and Example 1A (Recycled 2), which is the sample name corresponding to Example 1A after the recycled aerogel was subjected to the above-mentioned recycling once more.

[0183] Testing revealed that the polymer aerogel (maleimide-based aerogel) of Example 1A of the present invention has a glass transition temperature of approximately 250°C and a decomposition temperature of approximately 300°C, demonstrating good heat resistance. The heat resistance of the aerogel prepared from the recycled polymer was higher than that of the aerogel before recycling. This proves that both the polymer before and after recycling of the aerogel have good heat resistance and that the recycling process is green and environmentally friendly.

[0184] [Test example] The water solubility test results for the aerogels prepared in Examples 1A to 6A and Comparative Examples 1A to 4A are shown in Table 1A, and the test results for the water contact angle, cycle efficiency, thermal conductivity, and density of the aerogels prepared in Examples 1A to 8A are shown in Table 2A. The infrared spectrum test curves for Comparative Example 3A, Example 1A, and the aerogel recycled from Example 1A are shown in Figure 1, the NMR spectrum curves for the Examples and Comparative Examples are shown in Figure 2, and a scanning electron microscope photograph of the pore structure of the aerogel obtained in Example 1A is shown in Figure 3. The infrared spectrum test curves for the aerogel in Figure 1 and the aerogel in Figure 2 are shown. 1 From the H NMR spectrum curve, it can be determined that maleimide structures exist in the polymer aerogel structure.

[0185] [Table 2]

[0186] [Table 3]

[0187] Comparing the test results of Examples 1A to 6A and Comparative Examples 1A to 4A in Table 1A reveals that the aerogels prepared in accordance with the present invention are water-resistant and hydrophobic, that hydrophobic and water-resistant aerogels cannot be prepared using non-volatile bases such as sodium hydroxide, and that because N-phenylmaleimide is insoluble in aqueous ammonia, a hydrophobic aerogel cannot be prepared by directly dissolving N-phenylmaleimide in aqueous ammonia.

[0188] As can be seen from the test results for water contact angle, cycle efficiency, thermal conductivity, and density of Examples 1A to 6A in Table 2A, aerogels have lower thermal conductivity and density, making them suitable for use as direct replacements for current low-density insulation materials. The aerogel samples have significantly higher cycle efficiency, making them greener and more environmentally friendly. Aerogels with excellent hydrophobicity can be used as oil-water separation materials. Due to their porous surface structure (Figure 3), aerogels can be used as carriers for organic phase-change materials, catalysts, and filter materials. The test results for water contact angle, cycle efficiency, thermal conductivity, and density of the polymer aerogels of Examples 7A and 8A are similar to those of Example 5A.

[0189] [Preparation example 1B] (Preparation of Polymers in Examples of the Invention) 500ml of isoamyl acetate was placed in a 1000ml three-neck flask and charged with nitrogen to remove oxygen for 30 minutes. 24.5g of maleic anhydride and 26g of styrene were added to the flask. After complete dissolution, 0.4g of azodiisobutyronitrile was added, and the water bath temperature was raised to 70°C and the reaction was allowed to proceed for 7 hours. After the reaction, the reaction solution was centrifuged at 10,000 r / min for 10 minutes, the supernatant was removed, 500ml of methanol was added, and the mixture was stirred for 0.5 hours. This process of centrifuging and removing the supernatant was repeated twice. The reaction product was then vacuum dried at 140°C for 24 hours to obtain a styrene-maleic anhydride copolymer.

[0190] Example 1B 91.5 g of water was added to a capped glass bottle, followed by 3.5 g of ammonia water (25% by mass) and 5 g of maleic anhydride-styrene copolymer. After the cap was tightly fastened, the glass bottle was placed in an oven and heated to 95°C for 4 hours. After that, a homogeneous polymer solution (5% by mass) was obtained.

[0191] 15 ml of polymer solution was poured into a cylindrical aluminum foil spacer layer with a closed bottom. A 10 ml cylindrical glass vial (as a mold) was fixed to the center of the aluminum foil spacer layer so that the distance from the inner wall of the aluminum foil spacer layer to the outer edge and bottom of the glass vial was approximately 9 mm, and the top of the glass vial was approximately 1 mm higher than the solution. Next, the aluminum foil spacer layer was fixed to the center of a 50 ml (cylindrical) beaker (as a pre-freezing container) filled with 20 ml of polymer solution, with the bottom of the spacer layer approximately 5 mm away from the beaker, and the sample was frozen in a refrigerator at -30 °C for 2 hours. The frozen sample was transferred to a freeze dryer and freeze-dried (below -30 °C, below 10 Pa) for 72 hours to obtain a water-soluble polymer.

[0192] This water-soluble polymer was placed in an oven at 180° C. for 2 hours for dehydration and deamination, thereby obtaining a maleimide-based polymer aerogel (i.e., the polymer aerogel of the present invention) for both the inner and outer layers.

[0193] Infrared Spectroscopy and 1 The presence of maleimide structures in the polymer aerogel was confirmed by H NMR testing. The results showed that the molar ratio of maleimide-containing structural units was 43.6%, with the total molar amount of maleic anhydride-containing structural units and maleimide-containing structural units being 100%. The polymer aerogel had a water contact angle of 138.1°, a thermal conductivity of 0.0362 W / (mk), and a density of 72.3 Kg / m. 3 is.

[0194] 11 ml of dodecane phase change material was poured into the inner layer aerogel until it was full, and then the container was inverted. The excess phase change material on the surface of the aerogel phase change composite was wiped off to obtain a maleimide copolymer aerogel phase change heat storage material. At the time of use, the vaccine or the like can be placed in a glass vial.

[0195] Example 2B 91.5 g of water was added to a capped glass bottle, followed by 3.5 g of ammonia water (25% by mass) and 5 g of maleic anhydride-styrene copolymer. After the cap was tightly fastened, the glass bottle was placed in an oven and heated to 95°C for 4 hours. After that, a homogeneous polymer solution (5% by mass) was obtained.

[0196] 15 mL of polymer solution was poured into a 25 mL polytetrafluoroethylene cylindrical container with a copper bottom. A 10 mL cylindrical glass vial (as a mold) was fixed in the center of the polytetrafluoroethylene cylindrical container so that the distance from the inner wall of the polytetrafluoroethylene cylindrical container to the outer edge and bottom of the glass vial was approximately 9 mm, and the top of the glass vial was approximately 1 mm higher than the solution. The polytetrafluoroethylene cylindrical container was then placed on a copper pillar immersed in liquid nitrogen and completely frozen. After that, the frozen polymer solution ice pillar was transferred to a cylindrical aluminum foil spacer layer. The aluminum foil spacer layer was then fixed to the center of a 50 mL cylindrical beaker (as a pre-freezing container) filled with 20 mL of polymer solution so that the bottom of the spacer layer was approximately 5 mm away from the beaker, and the sample was frozen in a refrigerator at -30 °C for 2 hours. The frozen sample was transferred to a freeze dryer and freeze-dried (below -30 °C, below 10 Pa) for 72 hours to obtain a water-soluble polymer.

[0197] The water-soluble polymer was then dehydrated and deaminated in an oven at 180°C for 2 hours to obtain a maleimide-based polymer aerogel for both the inner and outer layers. The maleimide-based polymer aerogel in the inner layer was an anisotropic aerogel.

[0198] 11 ml of dodecane phase change material was poured into the inner layer aerogel until it was full, and then the container was inverted. The excess phase change material on the surface of the aerogel phase change composite was wiped off to obtain a maleimide copolymer aerogel phase change heat storage material.

[0199] Example 3B The preparation process was the same as that of Example 1B, except that the preparation process for the polymer solution of Example 1B was changed as follows: 94.9 g of water was added to a capped glass bottle, followed by 2.1 g of ammonia water with a mass fraction of 25% and 3 g of maleic anhydride-styrene copolymer. After the cap was tightly fastened, the glass bottle was placed in an oven and kept at 95°C for 4 hours before being removed, yielding a homogeneous polymer solution with a mass fraction of 3%. The amount of dodecane added was 11 ml.

[0200] Example 4B The preparation process was the same as in Example 2B, except that dodecane in Example 2B was replaced with tetradecane.

[0201] Example 5B 80 g of water was added to a reaction vessel having a polytetrafluoroethylene inner vessel, followed by 3.5 g of 25% mass fraction ammonia water and 5 g of maleic anhydride-isobutylene copolymer (Kuraray ISOBAM-08, molecular weight approximately 300,000). After sealing, the reaction vessel was placed in an oven and held at 95°C for 4 hours, after which it was removed to obtain a homogeneous polymer solution. This polymer solution was air-dried at room temperature to obtain a polymer containing maleamic acid groups and ammonium maleate groups.

[0202] 1 g of the polymer and 98.96 g of water were added to a capped glass bottle, followed by 0.04 g of 25% mass fraction ammonia water. After tightly fastening the cap, the glass bottle was placed in an oven and kept at 20°C for 0.5 hours. After removal, a homogeneous polymer solution with a mass fraction of 1% was obtained.

[0203] 15 ml of polymer solution was poured into a cylindrical aluminum foil spacer layer with a closed bottom. A 10 ml cylindrical glass vial (as a mold) was fixed to the center of the aluminum foil spacer layer so that the distance from the inner wall of the aluminum foil spacer layer to the outer edge and bottom of the glass vial was approximately 9 mm, while the top of the glass vial was approximately 1 mm higher than the solution. Next, the aluminum foil spacer layer was fixed to the center of a 50 ml polytetrafluoroethylene cylindrical container filled with 20 ml of the 0.5% polymer solution prepared in Example 1B, so that the bottom of the spacer layer was approximately 5 mm away from the polytetrafluoroethylene cylindrical container. The polytetrafluoroethylene cylindrical container was then placed on a copper column in a liquid nitrogen bath. After pre-freezing, the frozen sample was transferred to a freeze dryer and freeze-dried (below -30 °C, below 10 Pa) for 72 hours to obtain an anisotropic water-soluble polymer. This water-soluble polymer was then heat-treated in a 130 °C oven for 2 hours to dehydrate and deaminate it, yielding a maleimide-based polymer aerogel. 11 ml of dodecane phase change material was poured into the inner layer aerogel until it was full, and then the container was inverted. The excess phase change material on the surface of the aerogel phase change composite was wiped off to obtain a maleimide copolymer aerogel phase change heat storage material.

[0204] The test results for leakage, phase change temperature, and latent heat of phase transition are similar to those of Example 2B.

[0205] Example 6B 80 g of water was added to a reaction vessel having a polytetrafluoroethylene inner vessel, followed by 3.5 g of 25% mass fraction ammonia water and 5 g of maleic anhydride-isobutylene copolymer (Kuraray ISOBAM-08, molecular weight approximately 300,000). After sealing, the reactor was placed in an oven and held at 95°C for 4 hours, then removed to obtain a homogeneous polymer solution. This polymer solution was air-dried at room temperature to obtain a polymer containing maleamic acid groups and ammonium maleate groups.

[0206] 91.5 g of water was added to a capped glass bottle, followed by 3.5 g of ammonia water (25% by mass) and 5 g of the polymer containing maleamic acid groups and ammonium maleate groups obtained above. After tightly fastening the cap, the glass bottle was placed in an oven and heated to 150°C for 10 hours. After that, the bottle was removed, yielding a homogeneous copolymer solution with a mass fraction of 5%.

[0207] The preparation process was the same as in Example 2B, except that the 15 ml of polymer solution in Example 2B was replaced with the 5% copolymer solution described above in this example.

[0208] The maleimide-based polymer aerogel obtained by dehydration and deamination was tested, and then a phase change material was infused into the polymer aerogel according to the process of Example 2B.

[0209] The presence of maleimide structures in the polymer aerogel structure was confirmed by infrared spectroscopy and 1 The results of the H NMR test showed that the molar ratio of the maleimide-containing structural unit was 38.7%, with the total molar amount of the maleic anhydride-containing structural unit and the maleimide-containing structural unit being 100%. The polymer aerogel had a water contact angle of 127.6°, a thermal conductivity of 0.0369 W / (mk), and a density of 73.1 Kg / m. 3 is.

[0210] The test results of the leakage amount, phase change temperature, and latent heat of phase transition of the phase change material are similar to those of Example 2B.

[0211] [Recycle Example B] 5 g of the aerogel phase-change material prepared in Example 2B was added to a sealed glass bottle with a cap, followed by 1 g of 25% ammonia water and 15 g of water. The glass bottle was placed in an oven at 95°C for 2 hours to obtain a liquid (Fig. 6a). The liquid was then separated using a separatory funnel to obtain the recycled polymer aqueous solution (Fig. 6c) and the phase-change material (Fig. 6b).

[0212] The obtained polymer aqueous solution was used as a raw material for preparing an aerogel, and the phase change material was used as a raw material for preparing a phase change material, to prepare a phase change composite material according to the method of Example 2B.

[0213] The test results for leakage, phase change temperature and latent heat of phase transition are similar to those of Example 2B.

[0214] [Table 4]

[0215] As can be seen from Table 1B, the recyclable cold storage phase change composite material in the embodiment of the present invention has a higher adsorption amount for the phase change material and a lower leakage amount for the phase change material, and can be widely used in the fields of food preservation and cold chain transportation (such as cold chain transportation of vaccines and medicines).

[0216] [Table 5]

[0217] As can be seen from Table 2B, the porous aerogel of the present invention can be used to prepare a phase change composite material with very little latent heat loss, high cold storage capacity, and low leakage.

[0218] It should be noted that the above-described examples are used only to illustrate the present invention and are not intended to limit it. While the present invention has been described with reference to exemplary embodiments, it should be understood that the words used herein are descriptive and explanatory, rather than limiting. Changes may be made to the present invention within the scope of the claims, and modifications may be made to the present invention without departing from the scope and spirit of the present invention. While the present invention described herein relates to specific methods, materials, and examples, it is not intended that the present invention be limited to the specific examples disclosed herein. On the contrary, the present invention can be extended to all other methods and applications having the same functionality.

[0219] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference in their entirety.Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art.In the event of any discrepancy, the definitions in this specification shall prevail.

[0220] In this specification, when a material, substance, method, process, device, component, or the like is referred to using a prefix such as "known to those skilled in the art," "prior art," or the like, the subject matter so referred to includes not only those that are commonly used in the art at the time of filing this application, but also those that are not currently in common use but would be recognized in the art as being suitable for a similar purpose.

[0221] The end points of the ranges and any values ​​disclosed in the present application document are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​similar to these ranges or values.For numerical ranges, the end point values ​​of each range, the end point values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.In the following text, various technical solutions can be combined with each other in principle to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0222] In the context of this specification, for matters or issues not mentioned, what is known in the art shall apply without modification unless expressly stated otherwise.

[0223] Furthermore, any embodiment described in this specification can be freely combined with one or more other embodiments described in this specification, and any resulting technical solutions or technical concepts shall be deemed to be part of the original disclosure or original description of the present invention, and shall not be deemed to be new content not disclosed or contemplated in this specification, unless a person skilled in the art considers the combination to be obviously unreasonable. [Brief explanation of the drawings]

[0224] [Figure 1] 1 shows the Fourier transform infrared spectrum test curves of Comparative Example 3A, Example 1A, and the aerogel recycled from Example 1A. [Figure 2] 1 shows the H NMR spectrum curves of Example 1A and the aerogel recycled from Example 1A. [Figure 3] 1 is a scanning electron microscope photograph of the pore structure of the aerogel obtained in Example 1A. [Figure 4] 1 shows a temperature rise curve of the cool storage phase change material obtained in Example 1B. [Figure 5] 1 shows the emission spectrum at an excitation wavelength of 400 nm of the maleimide-based aerogel contained in the outer layer of the cold-storing phase-change material prepared in Example 1B. [Figure 6] 1A and 1B are schematic diagrams showing the appearance of a recyclable heat-storing phase-change composite material (a), a recycled phase-change material (b), and a recycled polymer aerogel (c) in Recycling Example B. FIG. [Figure 7] FIG. 1 is a schematic diagram showing the three-dimensional structure of the aerogel phase-change heat storage material with real-time temperature monitoring function obtained in Example 1B. [Figure 8] FIG. 1 is a schematic diagram showing the longitudinal cross-sectional structure of the aerogel phase-change heat storage material having real-time temperature monitoring function obtained in Example 1B.

Claims

1. A polymer aerogel, The polymer comprises a maleic anhydride group-containing structural unit and a maleimide group-containing structural unit, and the maleic anhydride group is 【Chemical 1】 The maleimide group refers to 【Chemistry 2】 refers to polymer aerogel.

2. 2. The polymer aerogel according to claim 1, wherein a molar ratio of the maleimide group-containing structural unit in the polymer is 5% to 70%, preferably 10% to 60%, more preferably 20% to 50%, relative to the total molar amount of the maleic anhydride group-containing structural unit and the maleimide group-containing structural unit, which is 100%.

3. 2. The polymer aerogel according to claim 1, wherein the polymer is derived from a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a group-containing structural unit of maleic acid and its ammonium salt, and a group-containing structural unit of maleamic acid and its ammonium salt; preferably, the polymer raw material is a copolymer of a polymerizable monomer containing one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt, and an olefin monomer; more preferably, the olefin monomer is at least one of α-methylstyrene, styrene, and isobutylene.

4. The polymer aerogel can be dissolved in ammonia water at 0-150°C to form an aqueous polymer solution; preferably, the aqueous polymer solution can be recycled by pre-freezing, freeze-drying, and heat treatment to obtain the polymer aerogel; and / or The polymer aerogel has a thermal conductivity of 0.025 to 0.05 W / (m.k), preferably 0.027 to 0.04 W / (m.k); and / or The polymer aerogel has a viscosity of 10 to 100 kg / m ３ , preferably 15 to 75 kg / m ３ and / or The polymer aerogel of claim 1, wherein the polymer aerogel is a three-dimensional porous material.

5. the polymer aerogel has a static water contact angle of 100° or more, preferably 110° or more, more preferably 135° or more; and / or 2. The polymer aerogel according to claim 1, wherein the polymer aerogel is insoluble in water, and preferably, the polymer aerogel is immersed in water at 20 to 40°C for 24 hours, preferably 72 hours, more preferably 168 hours without dissolving, to form an aqueous polymer solution.

6. 6. The polymer aerogel according to claim 1, wherein the polymer aerogel is prepared by reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under sealed conditions, followed by pre-freezing, freeze-drying, and heat treatment for dehydration and deamination.

7. 7. A method for preparing a polymer aerogel according to claim 1, comprising reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under sealed conditions, and then subjecting the polymer raw material to pre-freezing, freeze-drying, and heat treatment for dehydration and deamination to obtain a polymer aerogel.

8. (1) a step of reacting the polymer raw material with aqueous ammonia under a sealed condition to obtain an aqueous polymer solution; (2) a step of pre-freezing the aqueous polymer solution obtained in step (1) and then freeze-drying it to obtain a water-soluble polymer; (3) heat-treating the water-soluble polymer obtained in step (2) to obtain the polymer aerogel; 8. The method of claim 7, comprising:

9. In step (1), With the total mass of the reaction system being 100%, the mass fraction of the polymer raw material is 0.1% to 30%, preferably 0.5% to 10%, more preferably 1% to 5%, and the mass fraction of ammonia based on the mass of ammonia in the ammonia water is 0.0001% to 30%, preferably 0.01% to 10%, more preferably 0.1% to 1%, with the remainder being water; and / or The reaction conditions include a reaction temperature of 0 to 200°C, preferably 50 to 150°C, and more preferably 80 to 100°C, and / or a reaction time of 0.01 to 100 hours, preferably 0.5 to 10 hours, and more preferably 1 to 5 hours.

9. The method according to claim 8, characterized in that

10. In step (2), The aqueous polymer solution obtained in step (1) is pre-frozen in a mold, preferably with the cold source temperatures in different directions of the solution during pre-freezing being the same or different; and / or The freeze-drying conditions include a temperature of preferably −10° C. or lower and a vacuum of preferably 1000 Pa or lower.

9. The method according to claim 8, characterized in that

11. 9. The method according to claim 8, wherein in step (3), the heat treatment conditions include a temperature of 100 to 300°C, preferably 130 to 200°C, more preferably 150 to 190°C, and / or a time of 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours.

12. The preparation method according to one of claims 7 to 11, characterized in that the polymer raw material is a copolymer of an olefin monomer and a polymerizable monomer comprising one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt; preferably, the olefin monomer comprises at least one of α-methylstyrene, styrene, and isobutylene.

13. The preparation method according to one of claims 7 to 11, characterized in that the polymer raw material is at least one of styrene-maleic anhydride copolymer, styrene-maleic anhydride-vinyl silicone oil copolymer, maleic anhydride-isobutylene copolymer; preferably, the polymer raw material is at least one of styrene-maleic anhydride copolymer, maleic anhydride-isobutylene copolymer.

14. 1. A method for recycling polymer aerogel, comprising: The polymer aerogel is the polymer aerogel according to any one of claims 1 to 6 or prepared by the preparation method according to any one of claims 7 to 13, and the recycling method comprises the steps of: mixing and reacting the polymer aerogel and / or a material containing the polymer aerogel with aqueous ammonia under a sealed condition until an aqueous solution containing the recycled polymer is obtained; and optionally removing insoluble substances to obtain an aqueous solution of the recycled polymer; Preferably, the temperature of the mixing reaction is 0 to 200°C, preferably 50 to 150°C, more preferably 80 to 100°C, and / or the time of the mixing reaction is 0.01 to 100 hours, preferably 0.5 to 10 hours, more preferably 1 to 5 hours.

15. The recycling method further includes recycling the aqueous solution of the recycled polymer by pre-freezing, freeze-drying, and heat treatment to obtain a polymer aerogel; preferably, The cold source temperatures in different directions of the solution during pre-freezing are the same or different, and / or The freeze-drying conditions include a temperature of preferably −10° C. or lower and / or a vacuum of 1000 Pa or lower; and / or The recycling method according to claim 14, characterized in that the heat treatment conditions include a temperature of 100 to 300°C, preferably 130 to 200°C, more preferably 150 to 190°C, and / or a time of 0.1 to 10 hours, preferably 0.5 to 3 hours, more preferably 1 to 2 hours.

16. A recycled polymer aerogel obtained by the recycling method according to claim 14 or 15.

17. Use of the polymer aerogel according to one of claims 1 to 6, the polymer aerogel prepared by the preparation method according to one of claims 7 to 13, or the recycled polymer aerogel according to claim 16 as a porous material, preferably as a carrier for adsorbing an organic phase change material, a filter material, an oil-water separation material, or a heat insulating material.

18. A recyclable heat-storing phase-change composite material comprising a polymer aerogel and a phase-change material carried in the polymer aerogel, wherein the polymer aerogel is the polymer aerogel according to any one of claims 1 to 6, a polymer aerogel prepared by the preparation method according to any one of claims 7 to 13, or the recycled polymer aerogel according to claim 16.

19. The amount of the polymer aerogel is 2% to 20%, preferably 4% to 10%, and the amount of the phase change material is 80% to 98%, preferably 90% to 96%, based on the total mass of the recyclable heat-storing phase change composite material being 100%; and / or the phase change material is an organic phase change material, preferably having a phase change temperature of (-10) to 30°C and / or a phase change latent heat of 55 to 280 J / g; more preferably, the organic phase change material is an alkane organic phase change material, most preferably at least one of decane, dodecane, and tetradecane; and / or The recyclable heat-storing phase change composite material of claim 18, characterized in that under temperature conditions in which the phase change material is in a liquid state, the leakage amount of the phase change material in the recyclable heat-storing phase change composite material is less than 10 wt%, preferably less than 5 wt%, and more preferably less than 2 wt%.

20. The polymer aerogel is an anisotropic aerogel, preferably an anisotropic aerogel obtained using different cold source temperatures in one direction during pre-freezing; and / or The polymer aerogel can be dissolved in ammonia water at 0-150°C to form a polymer-containing solution, and preferably, the polymer-containing solution can be recycled to obtain the polymer aerogel by pre-freezing, freeze-drying, and heat treatment; and / or The density of the polymer aerogel is 100 kg / m ３ Preferably 15 to 80 kg / m ３ The recyclable heat-storing phase change composite material according to claim 18, characterized in that:

21. The polymer aerogel is prepared by reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under sealed conditions, followed by pre-freezing, freeze-drying, and heat treatment for dehydration and deamination; preferably, The cold source temperatures in different directions of the solution during pre-freezing are the same or different, more preferably the cold source temperatures in different directions of the solution during pre-freezing are different, thereby obtaining an anisotropic aerogel; Most preferably, the recyclable cold storage phase change composite material according to one of claims 18 to 20, characterized in that the temperature of the cold source is different in one direction of the solution during pre-freezing, thereby obtaining an anisotropic aerogel.

22. A method for preparing the recyclable heat-storing phase-change composite material according to any one of claims 18 to 21, comprising: loading a phase-change material into the polymer aerogel.

23. (1) a step of reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under a sealed condition to obtain an aqueous polymer solution; (2) a step of pre-freezing the aqueous polymer solution obtained in step (1) and then freeze-drying it to obtain a water-soluble polymer; (3) heat-treating the water-soluble polymer obtained in step (2) to obtain the polymer aerogel; (4) supporting a phase change material in the polymer aerogel; 23. The method of claim 22, comprising:

24. In step (1), With the total mass of the reaction system being 100%, the mass fraction of the polymer raw material is 0.1% to 30%, preferably 1% to 10%, more preferably 2% to 5%, and the mass fraction of ammonia based on the mass of ammonia in the ammonia water is 0.001% to 30%, preferably 0.01% to 10%, more preferably 0.1% to 1%, with the remainder being water; and / or In the pre-drying step, the aqueous polymer solution obtained in step (1) is subjected to different cold source temperatures in various directions, preferably different cold source temperatures in one direction; and / or 24. The method of claim 23, wherein a mold is inserted into the aqueous polymer solution obtained in step (1) before pre-freezing in step (2), and after heat treatment in step (3), the mold is optionally removed to obtain a polymer aerogel having cavities, and a phase-change material is supported in the polymer aerogel in step (4).

25. A recyclable heat-storing phase-change material with a real-time temperature monitoring function, having a layer structure including an inner layer formed of the recyclable heat-storing phase-change composite material according to any one of claims 18 to 21 or the recyclable heat-storing phase-change composite material prepared by the preparation method according to any one of claims 22 to 24, and an outer layer formed of a second polymer aerogel.

26. 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 further disposed 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 can change its optical signal with temperature change; preferably, the second polymer aerogel is selected from at least one of the polymer aerogels having photoluminescence properties and being able to change its optical signal with temperature change among the recyclable cold storage phase change composite materials according to one of claims 18 to 21; and the second polymer aerogel and the polymer aerogel in the recyclable cold storage phase change composite material can be the same or different; More preferably, the second polymer is a copolymer formed by a polymerizable monomer including one or more of maleic anhydride, maleimide, maleic acid and its ammonium salt, and maleamic acid and its ammonium salt, and styrene.

27. (1) a step of reacting a polymer raw material containing one or more of a maleic anhydride group-containing structural unit, a maleimide group-containing structural unit, a maleic acid and its ammonium salt group-containing structural unit, and a maleamic acid and its ammonium salt group-containing structural unit with aqueous ammonia under a sealed condition to obtain an aqueous polymer solution; (2) disposing the aqueous polymer solution in the space inside the spacer layer or in the space between the inside of the spacer layer and the mold, and then pre-freezing and freeze-drying the solution to obtain a water-soluble polymer; (3) heat-treating the water-soluble polymer obtained in step (2) and optionally removing the mold to obtain a polymer aerogel having voids; (4) forming an inner layer of a recyclable heat-storing phase-change material by loading a phase-change material into the polymer aerogel obtained in step (3); During and / or between steps (2), (3), and (4), and / or after step (4), wrapping the second polymer aerogel around the spacer layer to form an outer layer of recyclable heat-storing phase-change material; or, 27. The method for preparing a recyclable cold-storing phase-change material with real-time temperature monitoring function according to claim 25 or 26, characterized in that in step (2), the aqueous solution containing the second polymer aerogel and / or the second polymer aqueous solution is placed in the space outside the spacer layer to form an outer layer of the recyclable cold-storing phase-change material; preferably, the second polymer aqueous solution is the same as the polymer aqueous solution in step (1).

28. the mass fraction of the polymer in the aqueous polymer solution of the inner layer is 0.1% to 30%, preferably 1% to 10%, and / or 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 0.1% to 30%, preferably 0.5% to 10%, more preferably 1% to 5%, respectively; and / or 28. The method according to claim 27, characterized in that in the pre-drying stage of step (2), the aqueous polymer solution obtained in step (1) is subjected to different cold source temperatures in various directions, preferably different cold source temperatures in one direction.

29. Use of the recyclable cold-storing phase change composite material according to one of claims 18 to 21, or the recyclable cold-storing phase change composite material prepared by the preparation method according to one of claims 22 to 24, the recyclable cold-storing phase change material with real-time temperature monitoring function according to claim 25 or 26, or the recyclable cold-storing phase change material with real-time temperature monitoring function prepared by the preparation method according to claim 27 or 28 in the fields of food preservation and cold chain transportation.

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