Flexible shaped polymer composite inorganic phase change material as well as preparation method and application thereof

Abstract

The invention discloses a flexible shaped polymer composite inorganic phase change material and a preparation method and application thereof.According to the material, a nucleating agent, a thickening agent, a polymer monomer or polymer, a cross-linking agent and an initiator are introduced into the inorganic phase change material, so that the supercooling degree can be effectively reduced in the phase change process, and the heat energy storage and release efficiency is improved; meanwhile, the shape stability and excellent mechanical performance of the material are kept. The preparation method comprises the steps of raw material mixing, polymerization and cross-linking reaction, mold shaping and curing, and is simple in process and suitable for industrial production under mild conditions. The material can be widely applied to cooling cushions, pillows, summer sleeping mats, pet ice mats and other products, compared with traditional inorganic phase change materials, the material has better thermal stability, mechanical strength and durability, the problems of phase separation, embrittlement and the like can be effectively avoided, the service life is prolonged, and the product performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change materials, and particularly relates to a flexible shaped polymer composite inorganic phase change material, a preparation method thereof, and an application thereof. Background Art

[0002] Phase change materials are widely used in the field of cooling product materials because they can absorb or release a large amount of latent heat during the phase change process. Existing phase change materials mainly include organic phase change materials and inorganic phase change materials. Among them, inorganic phase change materials are more favored in personal cooling products due to their advantages such as large heat storage density, large thermal conductivity, small volume change during the phase change process, low cost, safety, and environmental friendliness.

[0003] However, in the actual application process of inorganic phase change materials, there are still problems such as serious attenuation of phase change latent heat, serious supercooling phenomenon, phase separation, and insufficient mechanical properties; specifically, due to the lack of sufficient nucleation sites of inorganic salt substances themselves in the solution, their crystallization process often requires a temperature condition much lower than the theoretical phase change temperature, resulting in a large supercooling degree in actual applications. This not only delays the phase change process but also reduces the efficiency of heat energy release and storage.

[0004] At the same time, due to the lack of sufficient molecular chain support in a single inorganic phase change material, it is prone to volume expansion or contraction when experiencing temperature changes, which in turn leads to phase separation or stratification phenomena inside the material, making it difficult to maintain a stable overall morphology, especially obvious during multiple thermal cycles or long-term use.

[0005] In addition, due to the relatively fragile nature of inorganic salt materials themselves, they are extremely prone to deformation, cracking, or even collapse when subjected to external mechanical stress, further restricting their practical application in flexible shaped products. Summary of the Invention

[0006] The main object of the present invention is to provide a flexible shaped polymer composite inorganic phase change material, a preparation method thereof, and an application thereof. By introducing a nucleating agent, a thickening agent, a polymer monomer, a cross-linking agent, and an initiator into the inorganic phase change material, the components act synergistically to achieve a flexible shaped polymer composite inorganic phase change material with low supercooling, stable morphology, excellent mechanical properties, and a simple preparation process.

[0007] To achieve the above object, a flexible shaped polymer composite inorganic phase change material proposed by the present invention, calculated by total mass percentage, comprises the following raw material components: 36-77% of phase change material, 1-2% of nucleating agent, 3-9% of thickening agent, 6-14% of solvent, 5-17% of polymer or polymer monomer, 0.2-1.3% of crosslinking agent, and 0.05-0.15% of initiator, wherein the sum of the mass percentages of each component is 100%; the crosslinking agent includes reversible crosslinking agent and irreversible crosslinking agent, wherein the reversible crosslinking agent accounts for 50-90% of the total crosslinking agent.

[0008] In a possible implementation manner, the nucleating agent includes one or more of sodium silicate, sodium sulfate, borax, silicon dioxide, aluminum trioxide, nano copper, magnesium chloride hexahydrate.

[0009] In a possible implementation manner, the thickening agent includes one or more of carbomer, xanthan gum, sodium alginate, hydroxypropyl methylcellulose, polyvinyl alcohol, gelatin, polyurethane, starch, microcrystalline cellulose, chitosan.

[0010] In a possible implementation manner, if the polymer is adopted, the polymer includes one or more of polymethacrylic acid, polyacrylic acid, sodium polyacrylate; If the polymer monomer is adopted, the polymer monomer includes one or more of acrylic acid, sodium acrylate, acrylamide, sodium methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate.

[0011] In a possible implementation manner, the irreversible crosslinking agent includes one or more of N,N'-methylenebisacrylamide, diethyl acrylate, diethyl methacrylate, carbamate.

[0012] In a possible implementation manner, the phase change material includes one or more of potassium carbonate crystal, sodium carbonate decahydrate, calcium chloride hexahydrate, sodium sulfate decahydrate, disodium hydrogen phosphate dodecahydrate.

[0013] A preparation method of an inorganic phase change material for preparing a flexible shaped polymer composite inorganic phase change material, the steps are as follows: S1. Raw material mixing: Mix the phase change material, nucleating agent, thickening agent, solvent, polymer monomer or polymer, crosslinking agent, and then heat and stir in an environment of 40-55 °C for 30-90 minutes to obtain a mixed solution; S2. Polymerization and crosslinking reaction: Add an initiator to the mixed solution obtained in S1, and then heat and stir in an environment of 40-55 °C for 1-5 minutes to obtain a completely reacted mixture; S3. Mould shaping and curing: Pour the mixture obtained in S2 into a mould, and then place the mould in an environment at 40 - 55 °C and heat for 30 - 90 minutes to obtain a flexible shaped polymer composite inorganic phase change material.

[0014] In a possible implementation, the crosslinking agent in S1 includes a reversible crosslinking agent and an irreversible crosslinking agent.

[0015] An application of a flexible shaped polymer composite inorganic phase change material, where the flexible shaped polymer composite inorganic phase change material is encapsulated in a bag as a bag product, and the bag product includes but is not limited to a cooling cushion, a cooling pillow, a cooling mat, and a pet ice pad.

[0016] In summary, the beneficial effects of the present invention are as follows: Compared with the prior art, the technical solution of the present invention introduces nucleating agents such as sodium silicate and silicon dioxide into the phase change material, provides abundant nucleation cores, reduces the nucleation energy barrier, enables the phase change to occur close to the theoretical temperature, inhibits the supercooling phenomenon, and improves the heat release and storage efficiency. Through the reaction of polymers such as polymethacrylic acid or polymer monomers such as acrylic acid with crosslinking agents such as diethyl acrylate to form a three-dimensional network structure, it provides molecular chain support for the material, buffers the volume change caused by temperature changes, prevents phase separation, and thickeners such as carbomer and starch increase the system viscosity to assist, ensuring the morphological stability of the material during multiple thermal cycles and long-term use. Moreover, thickeners such as starch also interact closely with the material and the polymer network to construct a reinforcing network, disperse external mechanical stress, avoid deformation, cracking or collapse, and improve the practicality in flexible shaped products.

[0017] And each component has good solubility and dispersibility in the selected solvent, and the reaction activity of the polymer or polymer monomer and the crosslinking agent is moderate, so that the preparation process only requires three main steps: raw material mixing, polymerization crosslinking reaction, and mould shaping and curing, and can be completed under mild conditions at 40 - 55 °C, greatly simplifying the preparation process, reducing costs, improving production efficiency, and being conducive to large-scale industrial production. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0019] Figure 1 It is the phase change latent heat diagram of Sample 1 in Embodiment 1 of the present invention; Figure 2 It is the supercooling degree curve diagram of Sample 1 in Embodiment 1 of the present invention; Figure 3 It is a comparison chart of the cooling time before cycling and after 1000 cycles of Sample 1 in Embodiment 1 of the present invention; Figure 4 It is a mechanical property diagram of Sample 1 in Embodiment 1 of the present invention; Figure 5 It is a comparison chart of the material morphology of Comparative Sample 1 in Comparative Example 1 and Sample 1 in Embodiment 1 of the present invention; Figure 6 It is a comparison chart of the curing results of Comparative Sample 2 in Comparative Example 2 and Sample 1 in Embodiment 1 of the present invention; Figure 7 It is a comparison chart of the cooling time before cycling and after 50 cycles of Comparative Sample 4 in Comparative Example 4 of the present invention; Figure 8 It is a comparison chart of the cooling time of Comparative Example 1 in Comparative Example 5 of the present invention; Figure 9 It is a process diagram for the preparation of the present invention.

[0020] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0021] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0022] The present invention provides a flexible shaped polymer composite inorganic phase change material, which, calculated by total mass percentage, comprises the following raw material components: 36-77% of phase change material, 1-2% of nucleating agent, 3-9% of thickening agent, 6-14% of solvent, 5-17% of polymer or polymer monomer, 0.2-1.3% of crosslinking agent, and 0.05-0.15% of initiator. Through the above multi-component formulation, not only the energy storage advantages of high latent heat and high thermal conductivity of inorganic phase change materials are fully utilized, but also the problems commonly encountered in the practical application of traditional inorganic phase change materials, such as supercooling, phase separation and mechanical brittleness, are solved by introducing other auxiliary components, thereby realizing an efficient and stable temperature control function.

[0023] Specifically, the phase change material is an inorganic phase change material, such as inorganic hydrates like potassium carbonate crystals, sodium carbonate decahydrate, calcium chloride hexahydrate, sodium sulfate decahydrate, disodium hydrogen phosphate dodecahydrate, etc. Its high latent heat and thermal conductivity enable it to be an ideal energy storage unit, which can regulate temperature by absorbing and releasing latent heat during solid-liquid phase change, thus achieving cooling or heating. By controlling the content of the phase change material at 36-77%, it can not only ensure sufficient heat storage capacity but also avoid excessive amounts that may damage the polymer network structure. When the content is less than 36%, the heat storage performance of the material significantly decreases; while when it exceeds 77%, due to the crystallization water of the hydrated salt providing latent heat, too high a proportion leads to increased inter-particle friction and affects network formation.

[0024] Secondly, since inorganic salt substances lack natural nucleation centers in a homogeneous solution and require extremely low temperatures to complete crystallization, to solve this problem, a nucleating agent is added. The nucleating agent can provide heterogeneous nucleation sites in the inorganic phase change material, reducing the energy required for crystallization, thereby enabling the phase change material to crystallize at a temperature close to the theoretical temperature, reducing the supercooling phenomenon, thus lowering the degree of supercooling and making the phase change process more rapid and efficient, which is conducive to timely releasing or absorbing heat energy.

[0025] Meanwhile, when existing inorganic phase change materials are melted, due to the excessive fluidity of the liquid, they are prone to layering or leakage. The addition of a thickening agent can increase the viscosity of the material system, enabling the phase change material to remain evenly distributed during the solid-liquid conversion process. At the same time, through the three-dimensional network structure formed by the thickening agent and cross-linked polymer monomers, the inorganic salt material can be fixed in the network, so that the material can maintain the stability of the phase change material even after multiple thermal cycles; ultimately preventing the phase change material from undergoing layering or phase separation during multiple phase change processes and improving the morphological stability of the material during long-term use.

[0026] In addition, the solvent includes one or more of water, ethylene glycol, glycerol, and ethanol; as a reaction medium, it can fully dissolve polymer monomers, cross-linking agents, and other additives, ensuring the uniform dispersion of each component before the reaction and facilitating the uniform progress of subsequent polymerization and cross-linking reactions; at the same time, selecting a solvent with good compatibility with the phase change material and organic components can reduce the interfacial tension and avoid layering caused by component mismatch, ensuring good compatibility between the phase change material and organic components, thereby solving problems such as uneven mixing, incomplete reaction, and microstructural instability caused by poor compatibility.

[0027] The polymer monomers include one or more of acrylic acid, sodium acrylate, acrylamide, sodium methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate; the polymers include one or more of polymethacrylic acid, polyacrylic acid, and sodium polyacrylate. The two can polymerize under the action of a crosslinking agent and an initiator to form long-chain polymers, constituting a continuous polymer network, enabling the material to form a continuous three-dimensional network after curing, providing a certain structural basis for the material, allowing the network to uniformly encapsulate the phase change material, and providing mechanical support for it during the phase change of the material, preventing phase separation or leakage caused by volume changes during the phase change process of the material, and solving the problems of morphological instability and mechanical brittleness easily caused by thermal cycling when the phase change material is used alone.

[0028] On this basis, the multi-functional groups in the irreversible crosslinking agent can connect each polymer chain to form a strong network structure. This network not only fixes the phase change material to prevent it from flowing out during melting, but also provides sufficient mechanical strength to resist external stress.

[0029] At the same time, since the inorganic phase change material and its encapsulation body are prone to cracking or deformation due to temperature fluctuations and external mechanical stress during the phase change process.

[0030] The initiator includes one or more of sodium sulfite, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, diethyl peroxydicarbonate, and diisopropyl peroxydicarbonate; it can decompose to generate free radicals under the condition of 40 - 55 °C, quickly initiate the polymerization reaction, and enable the polymer monomers to rapidly polymerize into chains. It ensures a fast and uniform reaction rate, can form a stable and homogeneous polymer network under mild conditions, thereby realizing the shaping and fixation of the overall structure. It solves the problems of slow or uneven polymerization reaction, ensures that subsequent crosslinking and structure formation are completed at a predetermined time and temperature, and contributes to the stability of the material properties.

[0031] Furthermore, the nucleating agent includes one or more of sodium silicate, sodium sulfate, borax, silicon dioxide, aluminum oxide, nano-copper, and magnesium chloride hexahydrate. In this embodiment, sodium silicate is preferably used. The nano-particles formed after sodium silicate is dissolved provide abundant heterogeneous nucleation sites for the inorganic phase change material, significantly reducing the critical supercooling degree required for phase change, enabling the material to quickly initiate the crystallization process when approaching the phase change temperature, and effectively suppressing the supercooling phenomenon. At the same time, the nano-particles adsorb on the surface of the hydrated salt crystals, regulating the crystal growth direction and rate, forming a finer and more uniform grain structure, increasing the phase change interface area, and enhancing the latent heat release efficiency.

[0032] Further, the thickener includes one or more of carbomer, xanthan gum, sodium alginate, hydroxypropyl methylcellulose, polyvinyl alcohol, gelatin, and polyurethane. In this embodiment, sodium alginate is preferably used; and the crosslinking agent includes one or more of N,N'-methylenebisacrylamide, diethyl acrylate, diethyl methacrylate, and carbamate, and diethyl acrylate is preferably used.

[0033] The synergistic effect of the thickener and the irreversible crosslinking agent realizes the breakthrough of material properties through double-network construction and interface optimization. The long-chain molecules of the thickener sodium alginate self-assemble through hydrogen bonds in water to form a three-dimensional colloidal network. Its carboxylic acid groups combine with water molecules to form a hydration layer, significantly increasing the viscosity of the system to 2000 mPa・s. The phase change material particles are uniformly dispersed and sedimentation is inhibited through the physical encapsulation effect. At the same time, its carboxylic acid groups adsorb on the particle surface to form a double-layer electric repulsion (ζ potential -35 mV), further maintaining the dispersion stability. The irreversible crosslinking agent diethyl acrylate crosslinks with the sodium acrylate monomer under the action of an initiator to form a three-dimensional network structure connected by covalent bonds, encapsulating the phase change material through the dual actions of physical entanglement and chemical adsorption, and inhibiting its migration and leakage.

[0034] The double-network structure penetrates each other through hydrogen bonds and van der Waals forces to form a composite system with both rigidity and flexibility: the colloidal network of sodium alginate provides initial mechanical support and dispersion stability, and the sodium polyacrylate network provides elasticity and structural strength. This synergistic effect endows the material with both high flexibility (tensile strength 0.8 MPa, elongation at break >500%) and morphological stability (deformation rate <5% after 1000 cycles). At the interface, the carboxylic acid groups of sodium alginate and sodium polyacrylate enhance the binding force through hydrogen bonds, further improving the network constraint ability. When the content of the thickener is less than 3%, the viscosity is less than 500 mPa・s, resulting in particle sedimentation; when the irreversible crosslinking agent exceeds 0.2%, the network crosslinking density is too high (>5 mmol / g), and the molecular chain segment movement is restricted, increasing the brittleness of the material (elongation at break <200%). By precisely controlling the ratio of the two, the material achieves the optimal balance of dispersion stability, mechanical properties, and phase change stability.

[0035] Meanwhile, the thickener also contains one or several of starch, microcrystalline cellulose, and chitosan. In this embodiment, microcrystalline cellulose is preferably added; it has a high specific surface area and abundant hydroxyl groups, can form a network through hydrogen bonds in the solvent, greatly increase the viscosity of the system, make the phase change material particles evenly dispersed, avoid sedimentation and aggregation, and improve the stability of the material. At the same time, microcrystalline cellulose can also enhance the mechanical properties of the material. Its rigid structure serves as a reinforcing phase and acts as a physical crosslinking point in the polymer network, increasing the modulus and hardness of the material, improving toughness, and making the material less likely to break and deform when stressed. Moreover, it can inhibit phase separation. During the phase change process, the network structure it forms restricts the flow and migration of the phase change material, reduces phase separation, maintains the energy storage performance and stability of the material, and extends the service life.

[0036] And microcrystalline cellulose can also have a synergistic effect with sodium silicate. Specifically, sodium silicate, as a nucleating agent, can provide crystal nuclei for the crystallization of the phase change material and reduce the supercooling degree. Microcrystalline cellulose provides more attachment sites for sodium silicate, makes it evenly dispersed, increases the number and uniformity of crystal nuclei, enables the phase change material to crystallize more rapidly and uniformly, further reduces the supercooling degree, and improves the energy storage efficiency and response speed. At the same time, the thickening and stabilizing effect of microcrystalline cellulose prevents sodium silicate from agglomerating and precipitating, ensuring its uniform distribution, and the interaction between sodium silicate and microcrystalline cellulose enhances the stability of the microcrystalline cellulose network structure, ensuring the long-term stability of the material properties. In addition to sodium silicate, microcrystalline cellulose is intertwined and combined with polymers or polymer monomers, participates in the formation of the polymer network, increases the crosslinking density and strength of the network, and the polymer network also plays a role in wrapping and fixing it. It synergizes with other thickeners to further increase the viscosity and stability of the system, and different thickeners interact to form a more complex and stable network structure to disperse and fix the phase change material particles.

[0037] In summary, through the ingenious combination of multiple components such as sodium silicate and microcrystalline cellulose, sodium alginate and diethyl acrylate, and polymer monomers or polymers, the present invention realizes a flexible shaped polymer composite inorganic phase change material with high-efficiency heat energy conversion, excellent morphological stability, and remarkable mechanical durability. Each component not only plays its unique role, but also produces an unexpected comprehensive performance improvement through the synergistic effect: the combined action of the nucleating agent and the thickener reduces the supercooling degree and regulates the crystal structure, the double-network system composed of the thickener and the crosslinking agent ensures uniform dispersion and improves the mechanical strength, and the efficient polymerization crosslinking of polymer monomers or polymers lays a stable foundation for the entire system. It is precisely this multi-level and multi-mechanism synergistic effect that enables the technical solution to achieve high-efficiency energy storage, rapid response, and long-term stability under mild reaction conditions.

[0038] Based on the above-disclosed flexible shaped polymer composite inorganic phase change material, such as Figure 8As shown, the present application also provides a method for preparing an inorganic phase change material for preparing a flexible shaped polymer composite inorganic phase change material, and the steps are as follows: S1. Raw material mixing: Mix the phase change material, nucleating agent, thickening agent, solvent, polymer monomer or polymer, crosslinking agent, and then heat and stir at 40-55 °C for 30-90 minutes to obtain a mixed solution; S2. Polymerization and crosslinking reaction: Add an initiator to the mixed solution obtained in S1, and then heat and stir at 40-55 °C for 1-5 minutes to obtain a completely reacted mixture; S3. Mold shaping and curing: Pour the mixture obtained in S2 into a mold, and then place the mold in an environment of 40-55 °C and heat for 30-90 minutes to obtain a flexible shaped polymer composite inorganic phase change material.

[0039] Meanwhile, the preparation process is significantly simplified through the multi-component synergistic effect of the raw material system disclosed in the inorganic phase change material. Specifically, the reaction activity, dispersion stability, and curing behavior of each component are efficiently matched at 40-55 °C. In the raw material mixing stage, inorganic phase change materials such as disodium hydrogen phosphate dodecahydrate are in a liquid state at 40-55 °C and form a uniform dispersion system with the nucleating agent sodium silicate. The nanoscale nucleation sites of sodium silicate directly reduce the supercooling degree through physical adsorption, without the need for complex pretreatment or multi-step crosslinking as in the prior art to inhibit the supercooling phenomenon.

[0040] Thickening agents such as sodium alginate form a colloid at this temperature, synchronously realizing the suspension stability of the phase change material and the medium function of the subsequent polymerization reaction, avoiding the steps of separately adding stabilizers or dispersants in the traditional process.

[0041] Polyacrylic acid-based or acrylic acid-based monomers and diethyl acrylate in the polymerization and crosslinking stage rapidly form a three-dimensional network within 1-5 minutes through a free radical polymerization reaction initiated by potassium persulfate at 40-55 °C. This high-efficiency crosslinking within a short time benefits from the high reaction activity matching of the monomer and the crosslinking agent, as well as the optimized decomposition rate of the initiator at this temperature. Compared with the multi-step crosslinking or high-temperature curing processes used in the prior art, the present invention integrates the polymerization and crosslinking processes within a single temperature range through raw material selection, without the need for complex temperature control or segmented treatment. The introduction of microcrystalline cellulose synergistically thickens with sodium alginate through physical entanglement in the mixing stage, avoiding the steps of additionally adding reinforcing fillers or post-treatment reinforcement in the prior art.

[0042] Its gelatinization behavior during the mold shaping stage further fills the network voids, enhancing the material strength, without the need to enhance mechanical properties through high-pressure molding or chemical modification as in traditional processes. The use of solvent water not only ensures the dissolution and dispersion of each component, but its slow evaporation behavior during the curing process extends the shaping time window, enabling the material to be shaped in a single mold without complex demolding or post-processing.

[0043] In summary, the preparation method of this invention application integrates multiple processes within a single temperature range through the interfacial action between the nucleating agent and the phase change material, the low-temperature rapid polymerization of polymer monomers and crosslinking agents, and the synergistic stabilization among various thickeners, achieving the simplification of the entire process from raw material mixing to product shaping. Example 1

[0044] In this example, the inorganic phase change material is disodium hydrogen phosphate dodecahydrate, the nucleating agent is sodium silicate, the thickeners are sodium alginate and microcrystalline cellulose, the solvent is water, the polymer monomer is sodium acrylate, the crosslinking agent is the irreversible crosslinking agent diethyl acrylate, and the initiator is potassium persulfate. The preparation steps are as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of sodium alginate, 4 g of microcrystalline cellulose, 14.5 g of water, 16 g of sodium acrylate, and 0.4 g of diethyl acrylate into a glass container, and heat and stir at 40°C for 60 min to obtain a uniform mixed solution.

[0045] S2. Polymerization and crosslinking reaction: Add 0.08 g of potassium persulfate to the mixed solution obtained in S1, and continue to stir at 40°C for 1 minute.

[0046] S3. Mold shaping and curing: Pour the uniformly stirred solution in S2 into a mold, and heat in an oven at 40°C for 60 min until completely shaped to obtain sample 1 of the flexible shaped polymer composite inorganic phase change material.

[0047] Among them, through the test and detection of sample 1 in this application, the phase change latent heat diagram as shown in Figure 1 , the supercooling degree curve diagram as shown in Figure 2 , the comparison diagram of the cooling time before cycling and after 1000 cycles as shown in Figure 3 , and the mechanical property diagram as shown in Figure 4 are obtained.

[0048] According to Figure 1-2 , for sample 1 obtained through the components and preparation method of Example 1, its phase change latent heat is 125.9 J / g; the supercooling degree is reduced from about 10°C to 1.7°C.

[0049] The sample was placed in a high and low temperature cycling chamber, and a high and low temperature cycling program was set to simulate cyclic use. After 1000 cycles, the sample was transferred to a 40 °C forced air drying oven to test its cooling time, and the Figure 3 results were obtained. According to Figure 3 , it can be seen that after the sample experienced 1000 cycles, its cooling time only decreased by 13%.

[0050] And according to Figure 4 the mechanical property test results, sample 1 has excellent mechanical properties, showing high strength and good flexibility.

[0051] In summary, according to the component ratio and preparation method of Example 1, the high-efficiency energy storage characteristics with a phase change latent heat of 125.9 J / g and a melting point of 31.3 °C were achieved. The synergistic effect of the nucleating agent and the network structure results in a supercooling degree of only 1.7 °C, far lower than more than 10 °C of traditional inorganic materials. The three-dimensional cross-linked network endows the material with excellent mechanical properties, which can withstand deformations such as bending, stretching, and compression without cracking, and is suitable for flexible application scenarios. The synergistic effect of the polymers significantly improves the cycle stability. After 1000 high and low temperature cycles, the cooling time only decays by 13%, while traditional materials can decay by 35% after 50 cycles. The material remains solid and shaped at 40 °C, with no liquid leakage during the phase change process, and the preparation process is completed under mild conditions of 40 - 55 °C without complex post-treatment. It has both high-efficiency energy storage, stable phase change, flexible mechanical properties, and process simplicity, and is suitable for temperature control products such as cooling cushions and pet ice pads. Example 2

[0052] On the basis of Example 1, the polymer monomer sodium acrylate was replaced with sodium polyacrylate; the specific steps are as follows: S1. Raw material mixing: 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of sodium alginate, 4 g of microcrystalline cellulose, 14.5 g of water, 16 g of sodium polyacrylate, and 0.4 g of diethyl acrylate were added to a glass container and heated and stirred at 40 °C for 60 min to obtain a uniform mixed solution.

[0053] S2. Polymerization and cross-linking reaction: 0.08 g of potassium persulfate was added to the mixed solution obtained in S1, and stirring was continued at 40 °C for 1 minute.

[0054] S3. Molding and curing in a mold: The solution stirred evenly in S2 was poured into a mold and heated in an oven at 40 °C for 60 min until completely shaped to obtain sample 2 of the flexible shaped polymer composite inorganic phase change material. Example 3

[0055] On the basis of Example 1, potassium persulfate was replaced with ammonium persulfate, and its preparation steps are as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of sodium alginate, 4 g of microcrystalline cellulose, 14.5 g of water, 16 g of sodium acrylate, and 0.4 g of diethyl acrylate into a glass container, and heat and stir at 40 °C for 60 min to obtain a uniform mixed solution.

[0056] S2. Polymerization and cross-linking reaction: Add 0.08 g of ammonium persulfate to the mixed solution obtained in S1, and continue to stir at 40 °C for 1 minute.

[0057] S3. Molding and curing in a mold: Pour the uniformly stirred solution in S2 into a mold, and heat it in an oven at 40 °C for 60 min until it is completely molded to obtain Sample 3 of the flexible molded polymer composite inorganic phase change material.

[0058] Examples 2 and 3 verified the flexibility of the invention formula and the robustness of the process by adjusting the raw material types (monomers or initiators).

[0059] In Example 2, the polymer monomer sodium acrylate was replaced with polyacrylic acid, aiming to explore the influence of pre-polymerized high molecular polymers on the material properties. Different from the in-situ polymerization and cross-linking of acrylic acid through an initiator in Example 1, polyacrylic acid, as a high molecular weight polymer, already has a certain chain structure, and its dispersibility, rheological properties, and cross-linking behavior in the system may be different, but the system can still form a stable three-dimensional network structure. The results show that its performance is similar to that of Example 1, demonstrating the diversity of polymer or monomer selection.

[0060] In Example 3, the initiator potassium persulfate was replaced with ammonium persulfate. Utilizing the property that ammonium ions may accelerate the polymerization reaction, efficient cross-linking was still achieved at the same polymerization temperature, verifying the universality of the initiator.

[0061] Examples 2 and 3 expand the range of raw material selection, reduce production costs or meet special requirements; and prove the synergistic effect of multiple component ratios, rather than relying on a single specific raw material, providing a direction for subsequent optimization, such as adjusting the hydrophilicity and hydrophobicity of the material through acrylic acid, or improving the polymerization efficiency through ammonium persulfate.

[0062] On the basis of Example 1, in order to further verify the necessity of key components, the present application added the following comparative examples. Comparative Example 1

[0063] Compared with Example 1, Comparative Example 1 lacked the thickening agent microcrystalline cellulose, and the preparation steps were as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of sodium alginate, 14.5 g of water, 16 g of sodium acrylate, and 0.4 g of diethyl acrylate into a glass container, heat and stir at 40 °C for 60 min to obtain a homogeneous mixed solution.

[0064] S2. Polymerization and crosslinking reaction: Add 0.08 g of potassium persulfate to the mixed solution obtained in S1, and continue to stir at 40 °C for 1 minute.

[0065] S3. Molding and curing of the mold: Pour the uniformly stirred solution in S2 into a mold, and heat it in an oven at 40 °C for 60 min until it is completely molded to obtain Comparative Sample 1 of the flexible molded polymer composite inorganic phase change material.

[0066] Among them, the comparison results of the material morphology between Comparative Sample 1 and Sample 1 are as Figure 5 shown. It can be seen from Figure 5 that Comparative Sample 1 without starch added has poor morphological stability and is prone to deformation and collapse under external force.

[0067] This is because the hydroxyl groups of starch form hydrogen bonds with the polymer network and fill the network voids through physical entanglement, synergistically enhancing the material structure with sodium alginate. Without starch, the network support force is insufficient, resulting in increased brittleness of the material. Comparative Example 2

[0068] Compared with Example 1, Comparative Example 2 removes all components related to polymerization, such as polymer monomers, crosslinking agents, and initiators. Its preparation steps are as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of sodium alginate, and 26 g of water into a glass container, heat and stir at 40 °C for 60 min to obtain a homogeneous mixed solution.

[0069] S2. Molding and curing of the mold: Pour the uniformly stirred solution in S1 into a mold, and heat it in an oven at 40 °C for 60 min until it is completely molded to obtain Comparative Sample 2 of the composite inorganic phase change material.

[0070] The comparison chart between Comparative Sample 2 and Sample 1 is Figure 6 , according to Figure 6 it can be known that Comparative Sample 2 without polymer crosslinking coating remains liquid after heating in an oven at 40 °C for 60 minutes, while Sample 1 has successfully formed a flexible molded inorganic phase change material under the same conditions. This shows that polymer crosslinking coating plays a key role in improving the morphological stability of the material, enabling it to maintain good structural integrity during the phase change process, which is beneficial to the long-term stability and reusability in practical applications. Comparative Example 3

[0071] Compared with Example 1, in Comparative Example 3, the nucleating agent sodium silicate was replaced with silicon dioxide, and the preparation steps were as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of silicon dioxide, 4.39 g of sodium alginate, 4 g of microcrystalline cellulose, 14.5 g of water, 16 g of sodium polyacrylate, and 0.4 g of diethyl acrylate into a glass container, and heat and stir at 40 °C for 60 min to obtain a uniform mixed solution.

[0072] S2. Polymerization and cross-linking reaction: Add 0.08 g of potassium persulfate to the mixed solution obtained in S1, and continue to stir at 40 °C for 1 minute.

[0073] S3. Molding and curing in a mold: Pour the uniformly stirred solution in S2 into a mold, and heat in an oven at 40 °C for 60 min until completely molded to obtain Comparative Sample 3 of the flexible molded polymer composite inorganic phase change material.

[0074] Through the test of Comparative Sample 3, the supercooling degree of Comparative Sample 3 was 3.1 °C, slightly higher than that of Example 1. It shows that Comparative Example 3 is more likely to have supercooling phenomenon during the phase change process, affecting its phase change stability and energy storage efficiency. This is because the surface hydroxyl groups of sodium silicate form hydrogen bonds with the phase change material, providing high-density heterogeneous crystal nucleus sites, while the surface activity of silicon dioxide is low and the nucleation efficiency is insufficient, resulting in delayed phase change crystallization. Comparative Example 4

[0075] Compared with Example 1, in Comparative Example 4, the thickening agent sodium alginate was replaced with polyvinyl alcohol, and the preparation steps were as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of polyvinyl alcohol, 4 g of microcrystalline cellulose, 14.5 g of water, 16 g of sodium acrylate, and 0.4 g of diethyl acrylate into a glass container, and heat and stir at 40 °C for 60 min to obtain a uniform mixed solution.

[0076] S2. Polymerization and cross-linking reaction: Add 0.08 g of potassium persulfate to the mixed solution obtained in S1, and continue to stir at 40 °C for 1 minute.

[0077] S3. Molding and curing in a mold: Pour the uniformly stirred solution in S2 into a mold, and heat in an oven at 40 °C for 60 min until completely molded to obtain Comparative Sample 4 of the flexible molded polymer composite inorganic phase change material.

[0078] By continuously heating the sample with the same thickness of Comparative Sample 4 in an oven at 37 °C and monitoring its temperature change using a multi-channel temperature recorder, the comparison chart of the cooling time before cycling and after 50 cycles as shown in Figure 7 is obtained.

[0079] It can be seen from Figure 7 Figure 7 that due to the phase separation problem in Comparative Example 4, the cycling stability is poor. After 50 cycles, the cooling time is reduced by 35%, indicating that the phase change performance decays rapidly, which shows that the compatibility of the thickener affects the cycling stability of the material.

[0080] This is because the sugar chain structure of sodium alginate has better compatibility with the phase change material and can effectively inhibit phase separation; polyvinyl alcohol is prone to phase separation with hydrated salts, resulting in rapid decay of the energy storage performance. Example 4

[0081] In order to further improve the performance of the inorganic phase change material, in this example, on the basis of the original components, a reversible cross-linking agent is added in one possible implementation mode.

[0082] Specifically, a flexible shaped polymer composite inorganic phase change material, calculated by total mass percentage, comprises the following raw material components: 36-77% of phase change material, 1-2% of nucleating agent, 3-9% of thickener, 16-14% of solvent, 5-17% of polymer or polymer monomer, 0.5-2% of reversible cross-linking agent, 0.1-0.3% of irreversible cross-linking agent, and 0.05-0.15% of initiator.

[0083] The present invention also provides a preparation method of an inorganic phase change material for preparing a flexible shaped polymer composite inorganic phase change material, and the steps are as follows: S1. Raw material mixing: Mix the phase change material, nucleating agent, thickener, solvent, polymer monomer, irreversible cross-linking agent, and reversible cross-linking agent, and then heat and stir for 30-90 minutes at 40-55 °C to obtain a mixed solution; S2. Polymerization and cross-linking reaction: Add an initiator to the mixed solution obtained in S1, and then heat and stir for 1-5 minutes at 40-55 °C to obtain a completely reacted mixture; S3. Molding and curing of the mold: Pour the mixture obtained in S2 into a mold, and then place the mold in an environment at 40-55 °C and heat for 30-90 minutes to obtain a flexible shaped polymer composite inorganic phase change material.

[0084] Among them, the reversible crosslinking agent contains dynamically reversible chemical bonds, such as borate bonds, disulfide bonds, etc. Taking the borate bond as an example, at room temperature, the borate bond maintains the crosslinked structure of the material, endowing the material with certain strength and stability. When the material is damaged, under the stimulation of external conditions (such as the temperature rising to 40 - 55 °C), the borate bond undergoes reversible cleavage and dissociation. The broken borate group and the adjacent hydroxyl group have a tendency to recombine. As the temperature decreases, the borate bond will form again, enabling the molecular chains at the damaged site to reconnect, achieving the self-healing effect. This dynamically reversible bonding process enables the material to have self-healing ability. After the material is mechanically damaged (such as scratched, cracked), it can spontaneously repair itself and restore its structural integrity and performance. For example, under appropriate conditions, the scratches on the material can automatically heal, and the mechanical properties such as tensile strength can be restored to more than 80% before damage, improving the service life and reliability of the material.

[0085] Meanwhile, during the phase change process, the material will experience volume expansion and contraction, which will generate stress inside the material. For traditional irreversible crosslinked materials, these stresses will gradually accumulate, leading to structural damage and performance degradation of the material. However, the dynamic chemical bonds of the reversible crosslinking agent can undergo reversible cleavage and recombination under the action of stress, playing a role in energy dissipation. When the material is stressed, the dynamic bond will break preferentially, absorbing and dispersing the stress to avoid damage to the material structure caused by stress concentration. When the stress is eliminated, the dynamic bond will form again, restoring the crosslinked structure of the material. This structure enables the material to still maintain good performance stability during multiple phase change cycles, reducing performance attenuation. For example, after 2000 phase change cycles, the energy storage performance attenuation of the material is less than 10%, while the material without adding the reversible crosslinking agent may show significant performance attenuation after 1000 cycles. This enables the material to better adapt to volume changes during phase change cycles, reduce structural damage, and thus improve the cycle stability of the material. Comparative Example 5

[0086] Compared with Example 1, in Comparative Example 5, the irreversible crosslinking agent diethyl acrylate was replaced with the reversible crosslinking agent glycine, and its preparation steps are as follows: S1. Raw material mixing: Add 37.16 g of disodium hydrogen phosphate dodecahydrate, 1 g of sodium silicate, 4.39 g of polyvinyl alcohol, 4 g of microcrystalline cellulose, 20 g of water, 16 g of sodium acrylate, and 0.4 g of glycine into a glass container, heat and stir at 40 °C for 60 min to obtain a uniform mixed solution.

[0087] S2. Polymerization and crosslinking reaction: Add 0.06 g of potassium persulfate to the mixed solution obtained in S1, and continue to stir at 40 °C for 1 minute.

[0088] S3. Mould shaping and curing: Pour the evenly stirred solution in S2 into the mould, and heat it in an oven at 40 °C for 60 min until it is completely shaped to obtain the comparative sample 5 of the flexible shaped polymer composite inorganic phase change material.

[0089] By placing Example 1 and the comparative sample 5 in a high and low temperature cycling chamber, setting a high and low temperature cycling program to simulate cyclic use, continuously heating the samples with the same thickness in an oven at 40 °C, and using a multi-channel temperature recorder to monitor their temperature changes, the comparative graph of the cooling time of Example 1 and the comparative sample 5 after 200 cycles as shown in Figure 8 is obtained.

[0090] It can be seen from Figure 7 that the cooling time of the comparative sample 5 after 200 cycles is 50 minutes less than that of Example 1. This is because, although the reversible cross-linking agent endows the material with stronger dynamic response ability, enabling it to adjust its own structure and properties according to environmental changes, making the material have more tunability and flexibility. However, the irreversible cross-linking agent provides stable and fixed properties, enabling the material to have higher stability and long-term reliability during long-term use. Example 5

[0091] The present invention also provides an application of the flexible shaped polymer composite inorganic phase change material, which is obtained by encapsulating the flexible shaped polymer composite inorganic phase change materials in Examples 1-4 into bags as bag products, and the bag products include but are not limited to cooling cushions, cooling pillows, cooling mats, and pet ice pads.

[0092] The temperature of the bag products prepared from the flexible shaped polymer composite inorganic phase change materials prepared in Examples 1-4 can be maintained at 24-33 °C for 3-5 hours.

[0093] In the drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0094] The above is only the preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A flexible shaped polymer composite inorganic phase change material, characterized in that, Calculated by total mass percentage, it contains the following raw material components: 36 - 77% of phase change material, 1 - 2% of nucleating agent, 3 - 9% of thickening agent, 6 - 14% of solvent, 5 - 17% of polymer or polymer monomer, 0.2 - 1.3% of crosslinking agent, and 0.05 - 0.15% of initiator, where the sum of the mass percentages of each component is 100%; the crosslinking agent includes reversible crosslinking agent and irreversible crosslinking agent, and among them, the reversible crosslinking agent accounts for 50 - 90% of the total crosslinking agent.

2. The flexible shaped polymer composite inorganic phase change material according to claim 1, characterized in that, The nucleating agent includes one or more of sodium silicate, sodium sulfate, borax, silicon dioxide, aluminum oxide, nano - copper, magnesium chloride hexahydrate.

3. The flexible shaped polymer composite inorganic phase change material according to claim 1, wherein The thickening agent includes one or more of carbomer, xanthan gum, sodium alginate, hydroxypropyl methylcellulose, polyvinyl alcohol, gelatin, polyurethane, starch, microcrystalline cellulose, chitosan.

4. The flexible shaped polymer composite inorganic phase change material according to claim 1, wherein If the polymer is used, the polymer includes one or more of polymethacrylic acid, polyacrylic acid, sodium polyacrylate. If the polymer monomer is used, the polymer monomer includes one or more of acrylic acid, sodium acrylate, acrylamide, sodium methacrylate, 2 - hydroxyethyl acrylate, 2 - hydroxyethyl methacrylate.

5. The flexible shaped polymer composite inorganic phase change material according to claim 1, characterized in that, The irreversible crosslinking agent includes one or more of N,N'-methylenebisacrylamide, diethyl acrylate, diethyl methacrylate, carbamate.

6. The flexible shaped polymer composite inorganic phase change material according to claim 1, wherein The phase change material includes one or more of crystalline potassium carbonate, sodium carbonate decahydrate, calcium chloride hexahydrate, sodium sulfate decahydrate, disodium hydrogen phosphate dodecahydrate.

7. A preparation method of an inorganic phase change material for preparing the flexible shaped polymer composite inorganic phase change material according to any one of claims 1-6, characterized in that, The steps are as follows: S1. Raw material mixing: Mix the phase change material, nucleating agent, thickening agent, solvent, polymer monomer or polymer, and crosslinking agent, and then heat and stir for 30 - 90 minutes at 40 - 55 °C to obtain a mixed solution. S2. Polymerization and crosslinking reaction: Add the initiator to the mixed solution obtained in S1, and then heat and stir for 1 - 5 minutes at 40 - 55 °C to obtain a completely reacted mixture. S3. Molding and curing of the mold: Pour the mixture obtained in S2 into a mold, and then place the mold in an environment of 40 - 55 °C and heat for 30 - 90 minutes to obtain a flexible - shaped polymer - composite inorganic phase - change material.

8. The preparation method of an inorganic phase change material according to claim 7, wherein, In S1, the crosslinking agent includes reversible crosslinking agent and irreversible crosslinking agent.

9. The application of the flexible shaped polymer composite inorganic phase change material according to any one of claims 1-6, characterized in that, The flexible - shaped polymer - composite inorganic phase - change material is encapsulated in a bag to form a bag product, and the bag product includes a cooling cushion, a cooling pillow, a cooling mat, and a pet ice pad.

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