Preparation method of dehumidification material for dehumidification rotating wheel

Abstract

The invention discloses a preparation method of a dehumidification material for a desiccant runner, which comprises the following steps: adding substances with a temperature-sensitive monomer and a hydrophilic ionic monomer into a modified graphene oxide dispersion liquid and a cross-linking agent mixed liquid respectively, and forming a polymer layer of which the cross-linking density is gradually reduced from inside to outside on the surface layer of graphene under the action of a catalyst, thereby obtaining the dehumidification material for the desiccant runner. An insulating heat-conducting material is added in the process; after polymerization is completed, a reducing agent is added for a reaction, reversible covalent bonds are formed between cross-linking agents, freeze drying is conducted, and hybrid foam is obtained; dipping the hybrid foam into an ethanol solution of a silane coupling agent to react to form a multistage reversible hydrogen bond; dispersing the hybrid foam into a resin solution for reaction to obtain composite slurry with multistage reversible bonds; coating a rotating wheel with the composite slurry in an electric field environment, and performing staged curing; the thermal runaway risk possibly caused by adsorption heat accumulation and the fire blast hidden danger caused by static electricity accumulation are fundamentally avoided.

Description

Technical Field

[0001] This invention relates to a dehumidifying wheel dehumidifying material, and more particularly to a method for preparing a dehumidifying wheel dehumidifying material. Background Technology

[0002] With the rapid development of electrochemical energy storage technology, the large-scale construction of battery warehouses has placed stringent demands on internal environmental control. Humidity control is a crucial aspect of ensuring battery storage safety and performance stability; excessive humidity can lead to battery leakage, corrosion, and even thermal runaway. Therefore, dehumidification rotary systems are widely used in such environments due to their high efficiency and continuous processing capabilities. The core efficiency of this system relies on the adsorption material loaded on the rotary wheel, whose performance directly determines dehumidification efficiency, energy consumption, and operational reliability.

[0003] Currently, commercial dehumidifier rotors mostly use silica gel, molecular sieves, or inorganic salt composite materials as adsorption media. During long-term cyclic adsorption-desorption processes, these materials continuously endure mechanical stress from periodic temperature changes, rotor rotation, and slight volume changes caused by moisture adsorption and desorption. Under repeated stress, traditional adsorption materials and their carrier structures are prone to cumulative damage such as microcracks, pulverization, or interfacial peeling. This type of damage is irreversible, leading to a decrease in adsorption capacity, increased resistance, and consequently a gradual decline in dehumidification efficiency, increased energy consumption, and even the need to shut down and replace the rotor. This affects the stability of continuous dehumidification in warehouses and increases maintenance costs. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a method for preparing dehumidifying materials for dehumidifying impellers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing dehumidifying material for dehumidifying impellers, comprising the following steps:

[0006] S1: In the modified graphene oxide dispersion and crosslinking agent mixture, substances with thermosensitive monomers and hydrophilic ionic monomers are added respectively. Under the action of a catalyst, a polymer layer with decreasing crosslinking density from the inside to the outside is formed on the graphene surface. Insulating and thermally conductive materials are added during this process.

[0007] S2: After S1 polymerization is completed, a reducing agent is added to react, so that reversible covalent bonds are formed between the crosslinking agents. After freeze drying, hybrid foam is obtained.

[0008] S3: The hybrid foam is immersed in an ethanol solution of a silane coupling agent modified with a 2-ureido-4[1H]-pyrimidinone group to form multilevel reversible hydrogen bonds;

[0009] S4: The hybrid foam treated by S3 is dispersed in a resin solution and reacted. A thermosensitive phase change material and an epoxy silane coupling agent are added for condensation to obtain a composite slurry with multi-level reversible bonds.

[0010] S5: The composite slurry is coated onto the rotating wheel under an electric field environment and then cured in stages.

[0011] In a preferred embodiment of the present invention, in step S1, the modified graphene oxide dispersion specifically comprises:

[0012] Silane-Br was added to the graphene oxide dispersion and reacted at 50-70℃ for 10-14h to obtain the modified graphene oxide dispersion, namely the graphene oxide-Br dispersion.

[0013] The graphene in the graphene oxide dispersion accounts for 4%-6% of the total mass.

[0014] The insulating and thermally conductive material is selected from one of the layered silicates such as aminated boron nitride nanosheets, aluminum nitride nanosheets, or montmorillonite, and the insulating and thermally conductive material accounts for 15-25% of the mass of the dispersion.

[0015] In a preferred embodiment of the present invention, in S1, the crosslinking agent is selected from two combinations of bismaleimide-terminated polyethylene glycol, furfuryl methacrylate, polyisocyanate, or secondary amine-terminated oligomers.

[0016] The thermosensitive monomer is selected from one of N-isopropylacrylamide, N-vinylcaprolactam, or N-acryloylpyrrolidine;

[0017] The substance possessing hydrophilic ionic monomers is selected from one of 2-acrylamido-2-methylpropanesulfonic acid, sodium styrene sulfonate, or vinyl sulfonic acid;

[0018] The molar ratio of the thermosensitive monomer and the hydrophilic ionic monomer is 7-9:2, the crosslinking agent accounts for 5-10% of the total monomer mass, and the molar ratio of the modified graphene oxide dispersion to the thermosensitive monomer is 1:7-9.

[0019] In a preferred embodiment of the present invention, in step S2, the reducing agent is selected from ascorbic acid, hydrazine hydrate, or sodium borohydride; the freeze-drying parameters are a temperature of -40 to -70°C, a time of 6-12 hours, and a cooling rate of 1-5°C.

[0020] In a preferred embodiment of the present invention, in S3, the concentration of the silane coupling agent with the 2-ureido-4[1H]-pyrimidinone group in ethanol is 0.5-2% w / v; the volume ratio of the solution to the hybrid foam is 3-5:1.

[0021] In a preferred embodiment of the present invention, in S4, the epoxy silane coupling agent is selected from one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propyltriethoxysilane, or 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane.

[0022] The mass ratio of epoxy silane coupling agent to resin solution is 2-4:100.

[0023] In a preferred embodiment of the present invention, in step S4, the resin solution is selected from one of terminal epoxy hyperbranched polysiloxane resin solution, terminal epoxy hyperbranched polyester resin solution, or terminal vinyl polysiloxane; the mass ratio of the resin solution to the hybrid foam is 1-3:1.

[0024] In a preferred embodiment of the present invention, in step S4, the thermosensitive phase change material is selected from materials whose inner layer is lithium chloride solution, lithium bromide solution or lauric acid and whose outer layer is poly(N-isopropylacrylamide); the thermosensitive phase change material accounts for 8-12% of the mass of the resin solution.

[0025] In a preferred embodiment of the present invention, in step S5, the electric field is a DC electric field applied to the opposite ends of the rotating wheel, and the electric field strength is 100-500V / mm, so that the graphene and aminated boron nitride nanosheets undergo orientation changes under the electric field.

[0026] In a preferred embodiment of the present invention, in step S5, the staged curing is as follows:

[0027] UV pre-curing: Apply UV light to the coated composite slurry surface for 25-35 seconds to gel the slurry surface.

[0028] The first stage of curing takes place at 75-85℃ for 3-5 hours, forming reversible covalent bonds.

[0029] The second stage of curing involves 1-3 hours at 118-122℃, 1-3 hours at 145-155℃, and 0.5-1.5 hours at 170-190℃.

[0030] The third stage of curing is carried out at 200-240℃ for 20-40 minutes.

[0031] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0032] (1) This invention provides a method for preparing dehumidifying material for dehumidifying impellers. By using boron nitride nanosheets to construct a through-through insulating and thermally conductive network, the heat of adsorption reaction can be efficiently discharged. The strongly hydrophilic sulfonic acid groups can strongly capture water molecules even at low humidity through ion-dipole interactions, reducing the humidity threshold for adsorption initiation. The electric field causes the sheet-like graphene and boron nitride to be arranged in a gradient orientation within the coating. The vertically oriented sheets form a rapid thermal diffusion pathway that penetrates the coating thickness, while the horizontally oriented sheets form a continuous but non-dense conductive network in the plane. These measures alleviate the problem from the root cause. This technology eliminates the local accumulation of adsorption heat, enhances the water absorption power and speed in low-humidity environments, and provides a channel for electrostatic dissipation. Compared with existing technologies, traditional dehumidification materials or rotors often use physically blended fillers or single-function coatings, making it difficult to simultaneously solve the coupling problems of heat, humidity, and electricity. This further enables the final dehumidification rotor material to achieve efficient and rapid dehumidification in special environments such as battery warehouses where temperature and humidity control and electrostatic sensitivity are required. At the same time, it fundamentally avoids the risk of thermal runaway caused by the accumulation of adsorption heat and the risk of combustion and explosion caused by the accumulation of electrostatics, significantly improving the safety and reliability of system operation.

[0033] (2) This invention provides a method for preparing dehumidifying materials for dehumidifying rotors. Through the formation of reversible covalent bonds in S2 and the introduction of quadruple hydrogen bonds in S3, the reversible covalent bonds can reversibly break and recombine at higher temperatures due to the different bond energies and dissociation temperatures of these two dynamic bonds. The UPy hydrogen bonds can rapidly and reversibly combine at room temperature. Together with the permanent covalent bonds of the resin matrix, they form a multi-level dynamic bonding system. When the material develops microcracks or fatigue damage due to swelling stress during long-term moisture absorption / desorption cycles, the weaker UPy hydrogen bonds break first to dissipate energy and prevent crack propagation; if… The damage is significant, but the reversible covalent bonds can be further broken and recombined. At the damaged site, these dynamic bonds can recombine under ambient room temperature conditions, achieving self-repair of the microstructure. In contrast to existing technologies, traditional hydrogels or polymer composite materials are prone to irreversible damage and performance degradation under cyclic stress, lacking self-repair capabilities, resulting in limited lifespan of the dehumidification rotor and the need for frequent replacement. The dehumidification material of this invention has damage healing capabilities and can withstand long-term, high-intensity operating conditions in the battery warehouse environment, greatly extending the service life of the rotor, reducing maintenance costs and downtime risks, and achieving long-term stable service of the material.

[0034] (3) This invention provides a method for preparing dehumidifying material for dehumidifying rotors. By introducing thermosensitive monomers and hydrophilic ionic monomers in S1 and combining them with a reduced graphene network, and introducing thermosensitive phase change material in S4, the resistance change of the material is modulated by a dual mechanism. First, there is a wet-electric response. After the hydrophilic ionic groups adsorb water, they dissociate into ions, which form an ion-electron dual conductive path with the graphene electron channel. The change in humidity directly changes the resistance. Second, there is a thermo-electric response. When the temperature changes, the thermosensitive polymer PNIPAM chain segments undergo phase change shrinkage / expansion, and the PCMs shell shrinks and releases internal hygroscopic salts, which will change the connection state of the conductive network, thereby modulating the resistance. This makes the dehumidifying material itself a highly sensitive humidity and temperature sensor. Its resistance signal can reflect the humidity saturation state and temperature state in real time and accurately. Compared with the prior art, traditional dehumidifying rotors require external independent temperature and humidity sensors to monitor the process, which has problems such as measurement lag, limited points, increased cost, and possible disconnection from the actual state of the material. Based on the resistance signal of the material itself, this invention can intelligently determine the adsorption saturation point and realize the control of the dehumidification-regeneration cycle. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart of a preferred embodiment of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0039] As shown in the figure, a method for preparing a dehumidifying material for a dehumidifying impeller includes the following steps:

[0040] S1: In the modified graphene oxide dispersion and crosslinking agent mixture, substances with thermosensitive monomers and hydrophilic ionic monomers are added respectively. Under the action of a catalyst, a polymer layer with decreasing crosslinking density from the inside to the outside is formed on the graphene surface. Insulating and thermally conductive materials are added during this process.

[0041] S2: After S1 polymerization is completed, a reducing agent is added to react, so that reversible covalent bonds are formed between the crosslinking agents. After freeze drying, hybrid foam is obtained.

[0042] S3: The hybrid foam is immersed in an ethanol solution of a silane coupling agent modified with a 2-ureido-4[1H]-pyrimidinone group to form multilevel reversible hydrogen bonds;

[0043] S4: The hybrid foam treated by S3 is dispersed in a resin solution and reacted. A thermosensitive phase change material and an epoxy silane coupling agent are added for condensation to obtain a composite slurry with multi-level reversible bonds.

[0044] S5: The composite slurry is coated onto the rotating wheel under an electric field environment and then cured in stages.

[0045] It should be noted that the preparation process of this invention utilizes atom transfer radical polymerization to grow gradient structure hydrogels in situ on the surface of graphene, thereby generating a sensing-response unit that directly converts humidity signals into electrical signals. Furthermore, it combines reversible covalent bonds and supramolecular interactions to construct a self-healing stress conduction network. Through the stress-induced adsorption site exposure mechanism, it fundamentally overcomes the problem of delayed response in low humidity.

[0046] Meanwhile, the orientation gradient structure constructed by the electric field-assisted coating process forms an efficient thermal diffusion pathway and an electron-ion dual-channel conductivity mechanism, thereby synergistically solving the two major safety hazards of adsorption heat accumulation and electrostatic accumulation, and endowing the material with temperature-sensitive regulation capability; ultimately, the deep coupling synergistic effect not only simultaneously solves the three major technical problems of high adsorption heat, slow response and electrostatic risk.

[0047] S1: In the modified graphene oxide dispersion and crosslinking agent mixture, substances with thermosensitive monomers and hydrophilic ionic monomers are added respectively. Under the action of a catalyst, a polymer layer with decreasing crosslinking density from the inside to the outside is formed on the graphene surface. Insulating and thermally conductive materials are added during this process.

[0048] In a preferred embodiment, in S1, the modified graphene oxide dispersion specifically comprises:

[0049] Silane-Br was added to the graphene oxide dispersion and reacted at 50-70℃ for 10-14h to obtain the modified graphene oxide dispersion, namely the graphene oxide-Br dispersion.

[0050] The graphene in the graphene oxide dispersion accounts for 4%-6% of the total mass.

[0051] The insulating and thermally conductive material is selected from one of the layered silicates such as aminated boron nitride nanosheets, aluminum nitride nanosheets, or montmorillonite, and the insulating and thermally conductive material accounts for 15-25% of the mass of the dispersion.

[0052] In a preferred embodiment, in S1, the crosslinking agent is selected from two combinations of bismaleimide-terminated polyethylene glycol, furfuryl methacrylate, polyisocyanate, or secondary amine-terminated oligomers.

[0053] The thermosensitive monomer is selected from one of N-isopropylacrylamide, N-vinylcaprolactam, or N-acryloylpyrrolidine;

[0054] The substance possessing hydrophilic ionic monomers is selected from one of 2-acrylamido-2-methylpropanesulfonic acid, sodium styrene sulfonate, or vinyl sulfonic acid;

[0055] The molar ratio of the thermosensitive monomer and the hydrophilic ionic monomer is 7-9:2, the crosslinking agent accounts for 5-10% of the total monomer mass, and the molar ratio of the modified graphene oxide dispersion to the thermosensitive monomer is 1:7-9.

[0056] It should be noted that in this step, by using a modified graphene oxide dispersion, with graphene as the framework, a polymer layer with gradient crosslinking density, dynamic reversible bonding and three-dimensional interconnection network is constructed in situ on it, thereby laying the microstructure foundation for the final material to achieve stress-electric-wet synergistic response and gradient mass transfer-electric conductivity.

[0057] Specifically, in step S1, silane-Br, namely 3-(trimethoxysilyl)propyl-2-bromo-2-methylpropionate, is reacted with a graphene oxide (GO) dispersion at 50-70°C for 10-14 hours. This causes the siloxane group (-Si(OCH3)3) at one end of the silane-Br molecule to hydrolyze under mild heating conditions and undergo a condensation reaction with oxygen-containing functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups on the surface of graphene oxide, thereby covalently anchoring the molecule to the GO sheets. The bromine atom (-Br) at the other end of the molecule is a highly efficient atom transfer radical polymerization (ATRP) initiation site. Through this reaction, GO is transformed from a hydrophilic two-dimensional nanosheet into a macromolecular initiator (GO-Br) with numerous ATRP initiators grafted onto its surface. This allows the GO surface to provide conditions for polymer growth in subsequent processing steps, enabling the formation of stable covalent bonds between the polymer and the graphene framework, and thus ensuring the transmission of stress and electrical signals.

[0058] Further, the modified GO-Br dispersion is mixed with specific monomers, crosslinking agents, and catalysts for atom transfer radical polymerization (ATRP). In this step, the monomers selected are thermosensitive monomers and hydrophilic ionic monomers. Specifically, thermosensitive monomers, such as N-isopropylacrylamide (NIPAM), have a low critical solution temperature (LCST) of approximately 32°C in their homopolymer, poly(N-isopropylacrylamide) (PNIPAM). The principle is that the amide and isopropyl groups on the PNIPAM molecular chain work together to make its dissolution behavior in water extremely sensitive to temperature. Below the LCST, the molecular chain hydrophilically extends; above the LCST, the molecular chain hydrophobically contracts. This characteristic directly contributes to solving the problem of adsorption heat accumulation, as the PNIPAM chain segments undergo phase transition contraction when the material adsorbs water molecules and releases heat, leading to a local temperature increase. On the one hand, this actively slows down further adsorption of water molecules, achieving self-braking; on the other hand, its volume contraction can synergistically change the resistance of the graphene network, providing a signal for temperature self-monitoring.

[0059] Simultaneously, substances possessing hydrophilic ionic monomers, such as 2-acrylamido-2-methylpropanesulfonic acid (AMPS), were introduced into the copolymerization system. AMPS molecules contain strongly hydrophilic sulfonic acid groups (-SO3H). Their mechanism of action is twofold: First, the sulfonic acid groups possess extremely strong hydration capabilities, enabling them to efficiently adsorb water molecules from the environment, especially in low relative humidity environments. Their ionic groups strongly bind water molecules through ion-dipole interactions, directly contributing to solving the problems of adsorption capacity and response delay in low-humidity environments. Second, after adsorbing water, the sulfonic acid groups can dissociate to release hydrogen ions (H+). + ), forming protons (H) inside the material. + This, combined with the electron conduction channels provided by graphene, forms an electron-proton synergistic conduction mechanism, enabling the material's resistance changes to more sensitively and linearly reflect environmental humidity, thus achieving excellent self-monitoring capabilities.

[0060] Crucially, the polymerization process employs a dynamic crosslinking agent combination: a combination of furfuryl methacrylate (FMA) and bismaleimide-terminated polyethylene glycol (BMI-PEG-BMI) crosslinking agents. The principle is that the furan ring in FMA and the bismaleimide end groups in BMI-PEG-BBMI can undergo a reversible Diels-Alder reaction in subsequent steps, forming dynamic covalent bonds—reversible covalent bonds. This introduces reconfigurable properties to the material network in this invention. During the long-term adsorption / desorption cycles of the dehumidification rotor, the periodic swelling and contraction of the hydrogel generates fatigue stress. In traditional materials, this stress accumulation easily leads to microcracks. However, in this material, when stress is locally concentrated, these dynamic covalent bonds can undergo reversible breakage, dissipating energy and reforming after stress relaxation.

[0061] Furthermore, this step, by controlling polymerization kinetics and adding polymer layers dropwise, intentionally constructs a gradient structure on the graphene surface with decreasing crosslinking density from the inside out. Specifically, in the initial stage of polymerization, the initiator concentration is high, the polymerization rate is fast, and a dense layer with a dense crosslinked network and restricted polymer chain movement is formed on the GO-Br surface. As polymerization progresses, the monomer concentration changes, and the polymer layer formed in the later stage has fewer crosslinking points, resulting in a more loose and porous structure, forming a porous layer. The core contribution of this gradient structure is that it optimizes the mass transfer path of water molecules within the material. When the ambient humidity increases, water molecules first rapidly pass through the outer loose porous layer and are then efficiently captured by the high-density hydrophilic groups in the inner dense layer. This gradient design, with a loose outer layer and a dense inner layer, significantly improves the adsorption response rate compared to a uniform structure and avoids the overall decrease in adsorption kinetics caused by premature surface saturation.

[0062] Furthermore, insulating and thermally conductive materials, such as aminated boron nitride nanosheets (BNNS-NH2), are simultaneously added during the polymerization process. BNNS is a high-performance thermally conductive material with a graphene-like layered structure but is itself an electrical insulator. The amino groups (-NH2) on the surface of BNNS-NH2 can form ionic or hydrogen bonds with carboxyl groups (from AMPS) in the polymer chain, allowing it to be well dispersed and chemically fixed in the polymer network, preventing agglomeration. The thermal conductivity of BNNS allows it to act as a thermal bridge, i.e., a heat transfer path, working synergistically with the graphene sheets to construct a three-dimensional, highly efficient thermally conductive network throughout the material. This directly addresses and effectively mitigates the safety risk of localized heat accumulation during adsorption, rapidly dissipating the heat generated during adsorption, suppressing local temperature rise, and thus reducing the possibility of thermal runaway. As an insulating layer, BNNS can physically isolate graphene sheets that are close to each other, preventing them from forming excessively dense conductive pathways that could lead to short circuits. This helps optimize the connectivity and stability of the conductive network, making the resistance-humidity response curve more linear and reliable.

[0063] In summary, step S1 prepared a hybrid material (MFHF) with a chemically bonded GO framework, on which a temperature-sensitive and highly hydrophilic smart polymer layer was gradient-grown, and high thermal conductivity insulating nanosheets were uniformly composited. This constructed a basic structural unit that combines rapid mass transfer channels (gradient structure), efficient adsorption and response sites (temperature-sensitive / hydrophilic monomers), excellent stress dissipation capabilities (dynamic bonds), and efficient thermal / electrical management functions (graphene / BNNS network).

[0064] S2: After S1 polymerization is completed, a reducing agent is added to react, so that reversible covalent bonds are formed between the crosslinking agents. After freeze drying, hybrid foam is obtained.

[0065] In a preferred embodiment, in step S2, the reducing agent is selected from ascorbic acid, hydrazine hydrate, or sodium borohydride; the freeze-drying parameters are a temperature of -40 to -70°C, a time of 6-12 hours, and a cooling rate of 1-5°C.

[0066] It should be noted that this step, based on the in-situ polymerization and nanocomposite process completed in step S1, involves the simultaneous chemical reduction and structural shaping of the precursor material. Through chemical reduction and freeze-drying processes, the intrinsic conductivity of the graphene framework is restored, the dynamic reversible covalent cross-linking network is activated and locked, and a three-dimensional porous foam structure with excellent mass transfer performance is constructed simultaneously. This step transforms the material from the precursor, i.e., the substance prepared in S1, into a functional structural unit material with self-monitoring, self-repairing, and rapid response capabilities.

[0067] Specifically, after the S1 polymerization reaction is completed, a reducing agent is added to the reaction system. In a preferred embodiment, ascorbic acid is preferably used. The principle is that ascorbic acid is an environmentally friendly and mild reducing agent that can selectively and efficiently reduce residual oxygen-containing functional groups (such as epoxy and carbonyl groups) on graphene oxide (GO) sheets, while maximally preserving the polymer layers successfully grafted onto the GO surface in step S1 and the formed polymer network structure. It is understood that the reduction of GO significantly improves its electron mobility and thermal conductivity because it restores the sp² hybridized conjugated structure of graphene. This lays the electrical and thermal foundation for the subsequent realization of highly sensitive resistance-humidity / temperature response (self-monitoring function) and efficient heat diffusion (solving the adsorption heat problem).

[0068] Furthermore, the crosslinking agent combination added in step S1, namely furfuryl methacrylate (FMA) and bismaleimide-terminated polyethylene glycol (BMI-PEG-BMI), has been incorporated as molecular units into the polymer backbone or side chains after polymerization. When the system is under the warm environment of the reduction reaction, or during a specific subsequent heating procedure, the furan ring in the FMA structure undergoes a reversible Diels-Alder reaction with the bismaleimide groups at the BMI-PEG-BMI end. This is a typical 4+2 cycloaddition reaction: the furan ring acts as a diene, and the maleimide acts as a dienophile; the two are reversibly covalently bonded, forming dynamic crosslinking points within the polymer network. This design solves the material durability problem in this invention. During the long-term moisture absorption and swelling-dehydration and shrinkage cycle of the dehumidifying wheel, the polymer network is subjected to cyclic stress, and traditional materials are prone to microcracks due to fatigue. In this material, when local stress concentration exceeds a threshold, these Diels-Alder bonds can undergo reversible fracture, dissipating energy and preventing crack initiation and propagation. When the stress is released or through gentle external heating, the fractured bonds can recombine, achieving self-repair of the microstructure. This endows the material with a damage healing ability similar to that of a living organism, which is key to its ultra-long service life.

[0069] Crucially, the freeze-drying process in step S2 is not simply dehydration, but rather the construction of a macroscopic three-dimensional porous framework, the locking of a gradient structure, and the eventual formation of a hybrid foam. The freeze-drying parameters are precisely controlled: a freezing temperature of -40°C to -70°C, a time of 6-12 hours, and a cooling rate of 1-5°C / min. First, the gel precursor containing a large amount of water is subjected to deep rapid freezing, causing the water molecules to condense into ice crystals. Preferably, a slow, programmed temperature-controlled cooling process of 1-5°C / min is used to allow the ice crystals to grow uniformly and slowly. Subsequently, the ice crystals directly sublimate from a solid state to a gaseous state, and the resulting space forms the porous structure that supports the entire material. Since a polymer layer with a dense inner layer and a sparse outer layer has already been formed through gradient polymerization in step S1, this gradient structure is replicated and amplified under the action of the ice crystal template into a permeable porous network with a gradient pore size distribution ranging from nanometer to micrometer scales. This significantly optimizes the diffusion path of water molecules within the material (gradient mass transfer channel), reduces mass transfer resistance, and enables the material to rapidly adsorb and desorb water when humidity changes, directly improving the dehumidification response speed. Simultaneously, the high porosity provides ample space for the swelling / shrinkage of the hydrogel components, avoiding the enormous internal stress caused by excessive volume changes.

[0070] In summary, step S2, through the synergistic processing of chemical reduction, dynamic bonding, and freeze-drying, transforms the precursor gel obtained in S1 into a solid hybrid foam (MFHF) with a highly conductive / thermal conductive framework, a dynamic adaptive network, and a hierarchical porous structure. This provides the foundation for the material's self-monitoring capabilities; by reducing GO, a highly sensitive resistance response channel is established; and the material is endowed with self-healing and stress-adaptive capabilities: by forming Diels-Alder dynamic covalent bonds, a reversible fracture-reorganization energy dissipation mechanism is created; simultaneously, the material is endowed with rapid mass transfer capabilities: through controlled freeze-drying, a through-hole gradient channel is constructed, greatly improving mass transfer efficiency.

[0071] S3: The hybrid foam is immersed in an ethanol solution of a silane coupling agent modified with a 2-ureido-4[1H]-pyrimidinone group to form multilevel reversible hydrogen bonds;

[0072] In a preferred embodiment, in S3, the concentration of the silane coupling agent with the 2-ureido-4[1H]-pyrimidinone group in ethanol is 0.5-2% w / v; the volume ratio of the solution to the hybrid foam is 3-5:1.

[0073] It should be noted that this step is a surface functionalization and interface enhancement treatment for the hybrid foam (MFHF) obtained in step S2. By chemically attaching the 2-ureido-4[1H]-pyrimidinone (UPy) group with reversible binding ability to the surface and pore walls of the hybrid foam, a supramolecular quadruple hydrogen bond is constructed inside the material. This, together with the covalent bond network and Diels-Alder dynamic covalent bond network constructed in steps S1 and S2, forms a multi-level dynamic bonding network with high strength, high toughness and multi-mode self-healing ability.

[0074] Specifically, the reagent used in this step is a silane coupling agent modified with an UPy group (UPy-Si). One end of this molecule is a hydrolyzable siloxane group (-Si(OCH3)3), and the other end is covalently linked to an UPy group via a linker arm. The UPy group is a supramolecular recognition unit, unique in that two UPy units can undergo specific, high-strength self-bonding via quadruple hydrogen bonds. The principle is that each UPy molecule can provide two hydrogen bond donors and two hydrogen bond acceptors, forming four directional hydrogen bonds through pairwise pairing. These bonds exhibit high binding strength, yet their binding and dissociation occur rapidly and reversibly at room temperature.

[0075] Further, in step S3, the hybrid foam is immersed in an ethanol solution of a silane coupling agent modified with 2-ureido-4[1H]-pyrimidinone groups. To achieve effective and uniform bonding of UPy-Si molecules on the MFHF foam, the UPy-Si molecules dissolve in the ethanol solution, and their terminal siloxane groups hydrolyze under trace amounts of water catalysis to generate active silanols (-SiOH). Subsequently, when the porous MFHF foam is immersed in this solution, the silanols undergo condensation reactions with the abundant hydroxyl (-OH) and carboxyl (-COOH) functional groups on the surface of the foam skeleton (mainly derived from graphene oxide and polymer chains) to form strong Si-OC or Si-O-Si covalent bonds. The UPy groups are then anchored to the entire three-dimensional network surface of the foam, including its abundant internal pore surfaces, through the silane.

[0076] Crucially, in a preferred embodiment, the concentration of UPy-Si in ethanol is controlled at 0.5-2% (w / v), and the volume ratio of solution to hybrid foam is 3-5:1. Too low a concentration (<0.5%) leads to insufficient grafting density, preventing the formation of an effective and continuous supramolecular hydrogen bond network, thus limiting the material's self-healing and toughening effects. Too high a concentration (>2%) causes UPy-Si molecules to self-condense in the solution or on the material surface, or to form an excessively thick surface layer, which can block the porous structure of MFHF itself, affecting its mass transfer and response performance. The solution volume ratio of 3-5:1 ensures that a sufficient and moderately excessive amount of UPy-Si solution completely wets and encapsulates the porous MFHF foam, guaranteeing that the reactants can fully diffuse to all internal surfaces for reaction, avoiding uneven grafting due to insufficient solution. Under these optimized conditions, a moderate and uniform coverage of UPy groups can be achieved on the MFHF surface, ensuring the effective construction of the subsequent supramolecular network without damaging the foam's pore structure.

[0077] This step complements the Diels-Alder bond formed in step S2, and the UPy quadruple hydrogen bonds can rapidly and reversibly bind and dissociate at room temperature. This means that microcracks, scratches, and other damage generated during use or processing can self-heal by relying on the reversible binding between UPy groups when left to stand at room temperature. This directly contributes to solving the problem of micro-damage accumulation caused by vibration and thermal stress in dehumidifying rotor materials during long-term operation, greatly improving the reliability and maintenance-free nature of the material.

[0078] Introducing UPy hydrogen bonds in this step creates a multi-level dynamic bonding system within the material, consisting of permanent covalent bonds, thermally reversible dynamic covalent bonds (Diels-Alder bonds), and room-temperature reversible supramolecular bonds (UPy hydrogen bonds). When the material is subjected to external forces, such as swelling stress, the weakest UPy hydrogen bonds break reversibly first, dissipating a large amount of energy and preventing crack initiation. If the stress further increases, the Diels-Alder bonds can break and reform, providing a second line of defense. The strongest covalent framework ensures that the overall integrity of the material remains intact. After the stress is relieved, these dynamic bonds can recover spontaneously or after mild stimulation.

[0079] Furthermore, through the connection of UPy-Si, a chemical anchor is established between the MFHF hybrid unit and the resin matrix to be introduced in the subsequent S4 step. The UPy groups form strong hydrogen bonds with complementary groups in the resin, such as amino and carboxyl groups, thereby greatly enhancing the interfacial bonding between the two phases. This ensures that the stress generated when the hydrogel swells / shrinks due to humidity changes can be more effectively transferred to the entire composite material through the interface, thus more sensitively modulating the resistance of the conductive network and improving the efficiency and reliability of the stress-electricity-humidity synergistic response mechanism.

[0080] In summary, the S3 step introduces the interaction forces of UPy quadruple hydrogen bonds into the material system, constructing a supramolecular network with dynamic self-adaptation and multi-mode self-healing. This network deeply synergizes with existing covalent and dynamic covalent networks, enabling the material to possess a wide range of spontaneous damage repair capabilities from room temperature to intermediate temperatures, as well as excellent impact energy dissipation characteristics. This provides crucial assurance for the dehumidification rotor material to maintain performance stability and structural integrity under harsh, long-term operating environments.

[0081] S4: The hybrid foam treated by S3 is dispersed in a resin solution and reacted. A thermosensitive phase change material and an epoxy silane coupling agent are added for condensation to obtain a composite slurry with multi-level reversible bonds.

[0082] In a preferred embodiment, in S4, the epoxy silane coupling agent is selected from one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propyltriethoxysilane, or 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane.

[0083] The mass ratio of epoxy silane coupling agent to resin solution is 2-4:100.

[0084] In a preferred embodiment, in step S4, the resin solution is selected from one of terminal epoxy hyperbranched polysiloxane resin solution, terminal epoxy hyperbranched polyester resin solution, or terminal vinyl polysiloxane; the mass ratio of the resin solution to the hybrid foam is 1-3:1.

[0085] In a preferred embodiment, in step S4, the thermosensitive phase change material is selected from materials whose inner layer is a lithium chloride solution, lithium bromide solution, or lauric acid, and whose outer layer is a poly(N-isopropylacrylamide) solution; the thermosensitive phase change material accounts for 8-12% of the mass of the resin solution.

[0086] It should be noted that in this step, the hybrid foam (MFHF) with gradient structure, dynamic network, and interface functionalization constructed in the previous steps is chemically bonded and physically composited with a continuous, tough, and reactive resin matrix. Simultaneously, temperature-sensitive phase change materials (PCMs) with active thermal management functions are introduced, ultimately resulting in a composite slurry with multi-level reversible bonds.

[0087] Specifically, step S4 first disperses the hybrid foam (MFHF) treated in S3 in the resin solution. Here, the hybrid foam acts as a functional filler, carrying all the core properties imparted by steps S1, S2, and S3: a conductive and thermally conductive network with a graphene / boron nitride framework, a gradient porous structure, a temperature-sensitive / strongly hydrophilic polymer layer, and surface-grafted UPy quadruple hydrogen bond sites. The resin solution then acts as a continuous phase matrix, providing the composite material with macroscopic mechanical strength, shape retention, and adhesion to the rotating wheel.

[0088] In a preferred embodiment, the resin solution is preferably an epoxy-terminated hyperbranched polysiloxane (EHP). This resin structure has numerous terminal functional groups and internal cavities, enabling it to significantly improve crosslinking density and material toughness, while its three-dimensional spherical structure helps reduce curing shrinkage stress. Furthermore, the terminal epoxy groups provide highly reactive ring-opening polymerization sites, capable of reacting with various functional groups such as amino and carboxyl groups, facilitating chemical bonding with MFHF and coupling agents. The polysiloxane backbone endows the material with excellent flexibility, thermal stability, and a hydrophobic substrate, the latter aiding in moisture desorption during hygroscopic-dehumidification cycles.

[0089] Furthermore, the addition of an epoxy silane coupling agent, 3-(2,3-epoxypropoxy)propyltrimethoxysilane (GPTMS), in this step is a core chemical strategy for strengthening interfacial bonding and constructing a multi-level reversible bond network. One end of the GPTMS molecule is a hydrolyzable methoxysilane, and the other end is a highly reactive epoxy group. Under stirring at 60°C during the reaction, the methoxysilane hydrolyzes to generate silanol (-SiOH). The silanol can undergo a condensation reaction with the MFHF surface, especially the surface rich in silanols after S3 UPy-Si modification, as well as the silanols in the EHP resin, to form strong Si-O-Si covalent bonds.

[0090] Simultaneously, the epoxy groups at the other end of GPTMS can undergo ring-opening copolymerization with the epoxy groups of the EHP resin itself, and can also react with amino, carboxyl, and other groups that may exist in the polymer chains on the MFHF surface. Therefore, GPTMS essentially acts as a molecular bridge connecting the MFHF functional filler and the EHP resin matrix, binding the two together through covalent bonds. This, together with the UPy supramolecular hydrogen bonds introduced in step S3 and the Diels-Alder dynamic covalent bonds formed in step S2, creates a multi-level dynamic bonding network at the interface and overall, ranging from strong to weak and from permanent to reversible. This network is the chemical basis for the material's high toughness, fatigue resistance, and self-healing ability over a wide temperature range from room temperature to intermediate temperatures.

[0091] Crucially, this step introduces thermosensitive phase change materials (PCMs) as an active thermal management unit. In a preferred embodiment, the core of the PCM is a high-concentration lithium chloride (LiCl) solution or a phase change substance such as lauric acid, and the outer shell is a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM). When the material adsorbs water vapor and generates heat, causing a local temperature increase: First, the outer layer of PNIPAM undergoes a hydrophilic-hydrophobic phase transition due to its low critical solution temperature (LCST, 32°C), changing from a swollen state to a contracted state. This contraction compresses the inner layer, causing the internal LiCl solution to be partially released into the surrounding polymer matrix through the pores or defects of the outer shell. As a highly hygroscopic salt, the exposure of LiCl significantly enhances the material's hygroscopic capacity at high temperatures, thereby compensating for the decrease in the polymer's physical adsorption capacity caused by the temperature increase.

[0092] In summary, step S4, through the synergistic operation of resin matrix composite, coupling agent interface strengthening, and the addition of thermosensitive phase change material, prepared a composite slurry with multi-level reversible bonds. The humidity-sensitive / electrical / thermal-conductivity response of MFHF was effectively transferred and integrated into the macroscopic composite material through strong interfacial bonding of covalent and supramolecular bonds.

[0093] S5: The composite slurry is coated onto the rotating wheel under an electric field environment and then cured in stages.

[0094] In a preferred embodiment, in S5, the electric field is a DC electric field applied to opposite ends of the rotating wheel, with an electric field strength of 100-500 V / mm, so that the graphene and aminated boron nitride nanosheets undergo orientation changes under the electric field.

[0095] In a preferred embodiment, in S5, the staged curing is as follows:

[0096] UV pre-curing: Apply UV light to the coated composite slurry surface for 25-35 seconds to gel the slurry surface.

[0097] The first stage of curing takes place at 75-85℃ for 3-5 hours, forming reversible covalent bonds.

[0098] The second stage of curing involves 1-3 hours at 118-122℃, 1-3 hours at 145-155℃, and 0.5-1.5 hours at 170-190℃.

[0099] The third stage of curing is carried out at 200-240℃ for 20-40 minutes.

[0100] It should be noted that in this step, the composite slurry prepared in the previous step is coated onto the rotating wheel for curing, transforming the composite slurry into a coating on the rotating wheel. During the curing process, a directional DC electric field is introduced to assist in the formation of its internal structure.

[0101] Specifically, in step S5, the composite slurry obtained in S4 is first coated onto the rotating substrate, while a DC electric field with a strength of 100-500 V / mm is applied to opposite ends of the substrate. The functional filler in the slurry—especially the multifunctional hybrid foam (MFHF) prepared in the previous steps and surface-modified with polymer and UPy groups—possesses anisotropic conductive / dielectric properties and a sheet-like morphology in its internal graphene and aminated boron nitride nanosheets (BNNS-NH2).

[0102] Under the influence of a strong DC electric field, sheet-like nanomaterials are subjected to a torque—electrophoretic or dielectric force—that aligns their long axis, i.e., the sheet plane, along the direction of the electric field. By controlling the electric field strength, the concentration gradient and orientation gradient can be controlled. Specifically, under the synergistic effect of sedimentation and electric field force, MFHF exhibits a decreasing content distribution from the substrate to the surface in the coating thickness direction. Furthermore, the alignment direction of the sheet-like nanomaterials also transitions from being mainly horizontal and parallel to the substrate surface near the substrate to being vertically aligned and perpendicular to the substrate surface on the coating surface.

[0103] Vertically oriented graphene / BNNS sheets create a highly efficient through-thermal conduction pathway in the coating thickness direction, rapidly transferring and dissipating the heat generated on the coating surface during water molecule adsorption to the metal substrate. This significantly suppresses localized temperature rise and reduces the risk of thermal runaway. Simultaneously, this anisotropic arrangement results in a continuous but not overly dense conductive network in the horizontal plane, facilitating the dissipation of surface static electricity. Furthermore, the high resistance in the thickness direction suppresses leakage current and optimizes the linearity of the resistance signal's response to humidity changes.

[0104] Furthermore, after coating, pre-curing is performed using UV light with a wavelength of 365nm and an intensity of approximately 100mW / cm² for 25-35 seconds. This rapidly fixes the gradient structure. The concentration and orientation gradients formed under the influence of the electric field relax and break down due to Brownian motion or flow after the electric field is removed. UV irradiation induces the resin-terminated epoxy group hyperbranched polysiloxane in the slurry to gel in the presence of a photoinitiator, forming a rigid network shell. This shell acts like a mold, freezing the gradient-distributed MFHF and nanosheets, which are still under the influence of the electric field, in situ. After this pre-fixation, thermal curing is performed to completely fix the composite slurry coating formed on the patent.

[0105] The first stage of thermosetting involves curing at 75-85℃ for 3-5 hours. At this mild temperature, the EHP resin matrix begins initial crosslinking, providing basic strength. More importantly, this temperature promotes the formation of various dynamic bonds. The UPy quadruple hydrogen bonds introduced in step S3 can efficiently self-assemble at this temperature, forming strong and reversible supramolecular crosslinking points. Simultaneously, the Diels-Alder dynamic covalent bonds formed from the furan / maleimide pair in step S2 also undergo efficient forward reaction at this temperature, forming reversible covalent crosslinks. The silane and epoxy ends of the epoxy silane coupling agent (GPTMS) also react fully with the matrix and filler at this temperature, strengthening the interface. The goal of this stage is to initially form a network framework that combines strength and dynamism.

[0106] The material is then heated further for a second stage of curing, which is performed in a stepped manner: 118-122℃ for 1-3 hours, 145-155℃ for 1-3 hours, and 170-190℃ for 0.5-1.5 hours. During the 1-3 hours at 118-122℃, the Diels-Alder bonds undergo a reversible reverse reaction, i.e., the reverse Diels-Alder reaction, resulting in the breaking of dynamic covalent bonds. This provides a relaxation and rearrangement temperature for the high-stress polymer segments frozen in a non-equilibrium state due to rapid molding in the previous step. During this process, the breaking and rearrangement of dynamic bonds effectively dissipates and redistributes the internal stress of the material, improving the coating's crack resistance and fatigue resistance. Simultaneously, while the UPy hydrogen bonds may weaken at this temperature, they are not completely destroyed and can still provide partial crosslinking.

[0107] Furthermore, as the temperature increases, the Diels-Alder reverse reaction becomes dominant, and the dynamic covalent bonds are essentially broken. However, at this point, the irreversible covalent crosslinking reactions between the epoxy groups in the resin matrix-EHP, and between the epoxy groups and the amino / carboxyl groups on the filler surface, are strongly accelerated and tend to be complete. The formation of these permanent covalent bonds ultimately fixes the stress-relaxed optimized polymer network conformation, as well as the filler gradient and orientation structure constructed by the electric field.

[0108] The final third stage of curing involves curing at 200-240℃ for 20-40 minutes. This stage is a high-temperature short-time treatment under an inert atmosphere to deeply thermally reduce the graphene. Although a chemical reducing agent is used in S2, this high-temperature treatment can further remove residual oxygen-containing functional groups on the graphene sheets, significantly improve the area and continuity of its sp² carbon domains, and further enhance the conductivity of the material. This makes the humidity / temperature self-monitoring signal based on resistance changes more sensitive, stable, and reliable.

[0109] Example 1:

[0110] Silane-Br, namely 3-(trimethoxysilyl)propyl-2-bromo-2-methylpropionate, was added to a graphene oxide dispersion, wherein the mass fraction of graphene oxide was 5%. The mixture was reacted at 60°C for 12 hours. During this process, the siloxane groups of the silane-Br molecule hydrolyzed and condensed with the oxygen-containing functional groups on the GO surface, thereby covalently grafting the ATRP initiator site (-Br) onto the GO sheets, resulting in a modified graphene oxide (GO-Br) dispersion.

[0111] Subsequently, furfuryl methacrylate (FMA) and bismaleimide-terminated polyethylene glycol (BMI-PEG-BMI) were added to the GO-Br dispersion as crosslinking agents, with a total mass of 8% of the total mass of subsequent monomers. Next, the thermosensitive monomer N-isopropylacrylamide (NIPAM) and the hydrophilic ionic monomer 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were added at a molar ratio of 8:2, and the molar ratio of GO-Br to NIPAM was 1:8. Atom transfer radical polymerization (ATRP) was initiated in a CuBr / PMDETA catalytic system.

[0112] A polymer layer was grown in situ on the GO-Br surface using N-isopropylacrylamide (NIPAM), a thermosensitive monomer, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), a hydrophilic ionic monomer, forming a gradient structure with decreasing crosslink density from the GO sheet surface outwards. This polymer layer integrates the thermosensitive phase change characteristics of the NIPAM segments with the strong hydrophilic proton conductivity of the PAMPS segments. During polymerization, 20% by weight of aminated boron nitride nanosheets (BNNS-NH2) were simultaneously added as an insulating and thermally conductive filler, ensuring uniform dispersion and embedding within the polymer network to construct a preliminary thermal and insulating barrier.

[0113] After the S1 polymerization reaction was complete, ascorbic acid was added to the system as a reducing agent to initiate the reaction. This process partially reduced the graphene oxide in GO-Br, restoring its conjugated structure to improve electrical and thermal conductivity. Simultaneously, the warm environment of the reaction system promoted a Diels-Alder reaction between the FMA furan rings integrated into the polymer network and the bismaleimide end groups of BMI-PEG-BMI, forming reversible dynamic covalent crosslinks. After the reaction, the resulting gel was freeze-dried, programmed to decrease to -55°C at a rate of 2°C / min, and then freeze-dried at this temperature for 9 hours. After ice crystal sublimation, a hybrid foam (MFHF) with a three-dimensional interconnected porous structure was obtained, retaining the gradient polymer structure, dynamic covalent bonds, and uniformly dispersed BNNS within it.

[0114] The hybrid foam (MFHF) obtained from S2 was impregnated in an ethanol solution of 1% (w / v) silane coupling agent (UPy-Si) modified with 2-ureido-4[1H]-pyrimidinone (UPy) groups, with a solution-to-foam volume ratio of 4:1. The reaction was carried out at room temperature for 12 hours. During this process, the siloxane groups at one end of the UPy-Si molecules hydrolyzed and condensed with functional groups such as hydroxyl groups on the surface of the MFHF foam framework, thereby firmly anchoring the UPy groups to the entire inner and outer surfaces of the foam in the form of covalent bonds. After drying, abundant UPy supramolecular units were introduced into the MFHF material. These units can interact with each other through strong quadruple hydrogen bonds, constructing a dynamic supramolecular network that can rapidly and reversibly bind at room temperature. This network, in conjunction with the dynamic covalent bond network formed in S2, endows the material with multi-mode self-healing and high toughness.

[0115] MFHF hybrid foam treated with S3 was dispersed in a hyperbranched polysiloxane EHP resin solution at a mass ratio of 2:1. Subsequently, 10% (by weight) of thermosensitive phase change material (PCMs) was added to the mixture. The PCMs consisted of a lithium chloride solution as the inner layer and poly(N-isopropylacrylamide) as the outer layer. Simultaneously, 3% (by weight) of epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane (GPTMS) was added. The reaction was carried out at 60°C. GPTMS acted as a molecular bridge; its silyl group at one end reacted with MFHF and the resin, while the epoxy group at the other end participated in resin crosslinking. This chemically bonded the functional filler, PCMs, and resin matrix together to form a homogeneous composite slurry with multi-level reversible bonds (covalent bonds, dynamic covalent bonds, and supramolecular hydrogen bonds).

[0116] The composite slurry prepared by S4 was uniformly coated onto the surface of a dehumidifying rotary wheel substrate. Simultaneously, a DC electric field of 300 V / mm was applied to opposite sides of the substrate and maintained until the slurry was initially set. Under this electric field, the sheet-like nanomaterials in the slurry underwent electrophoretic orientation, forming a gradient orientation structure in the coating thickness direction that transitioned from parallel alignment on the substrate surface to perpendicular alignment on the surface layer.

[0117] After coating, the coating surface is immediately irradiated with ultraviolet light (wavelength 365nm) with an intensity of 100 mW / cm² for 30 seconds for pre-curing, so that the surface layer can be rapidly gelled to fix the gradient structure induced by the electric field.

[0118] Then, a phased thermosetting process is carried out: the first stage of curing is carried out at 80°C for 4 hours to promote the initial cross-linking of the resin and ensure the self-assembly of UPy hydrogen bonds and the full formation of Diels-Alder dynamic covalent bonds, thus constructing a dynamic cross-linked network.

[0119] The second stage of curing involves a stepped temperature increase. First, curing is performed at 120°C for 2 hours. This temperature can trigger the reversible breakage of some Diels-Alder bonds, which helps to relax the internal stress of the material. Then, curing is performed at 150°C for 2 hours, and finally at 180°C for 1 hour to complete the deep curing of the resin matrix, form a permanent covalent cross-linked network, and ultimately lock the microstructure of the material.

[0120] The third stage of curing involves curing at 220℃ in an inert atmosphere for 30 minutes, which deeply thermally reduces the graphene in the material, further improving its conductivity and optimizing its electrical properties. Ultimately, a high-performance composite coating material with a gradient structure, multi-level dynamic bonding, and temperature- and humidity-sensitive synergistic functions is formed on the dehumidification rotor.

[0121] Experiment 1:

[0122] Based on Example 1, several examples were prepared by changing the addition ratio of boron nitride nanosheets, the amount of hydrophilic monomer AMPS, and the electric field strength of electric field assisted coating. Thermal conductivity, low humidity adsorption kinetics, surface resistance and antistatic properties were tested respectively.

[0123] The thermal conductivity test employs the internationally recognized laser flare method. At the start of the experiment, the sample is placed in a sample holder, ensuring good contact with the bottom of the holder, and then placed into the instrument's test chamber. The test chamber is either evacuated or filled with inert gas to eliminate interference from air convection. During instrument operation, a short laser pulse is uniformly irradiated onto the lower surface of the sample, applying a momentary thermal excitation. An infrared detector located directly above the sample monitors the temperature change over time on the upper surface due to heat conduction. This typical "temperature rise-time" curve is the key raw data for calculation. By analyzing the time required for the maximum temperature rise to reach half of its maximum (i.e., the half-heating time), the instrument software can use the classic Cowan model or the improved Capletta model to directly obtain the material's thermal diffusivity. This thermal diffusivity reflects the rate of heat propagation within the material and is an inherent property of the material itself.

[0124] Specific heat capacity is measured using a comparative method, which involves testing the sample under the same conditions with a standard sample whose specific heat capacity is known, and then calculating the specific heat capacity of the sample using energy equivalence relationships. The sample density is determined by the ratio of the dry weight measured using a high-precision analytical balance to the volume calculated from the diameter and thickness.

[0125] Ultimately, the thermal conductivity in the thickness direction of the material is calculated using a core physical formula: Thermal conductivity = Thermal diffusivity × Specific heat capacity × Density. This formula links the three fundamental thermophysical parameters of the material, and its physical meaning lies in the fact that thermal conductivity comprehensively reflects the material's ability to store and conduct heat. Through this series of standardized operations and calculations, we can obtain accurate values ​​that directly characterize the material's thermal conductivity in the vertical direction, providing a solid experimental basis for evaluating its thermal management effectiveness.

[0126] Low-humidity adsorption kinetics testing was conducted using a dynamic moisture adsorption analyzer. The instrument first introduced dry, pure nitrogen carrier gas into the chamber at a high temperature to thoroughly dry the sample for an extended period until its mass no longer changed. This ensured the sample was absolutely dry at its initial state, and the mass under this condition was recorded as a baseline. Next, the instrument precisely controlled the chamber temperature at 25°C and mixed the dry carrier gas with water vapor-saturated moisture to establish and stabilize the relative humidity within the chamber at the target low-humidity condition of 30% RH. Upon switching humidity levels, the instrument's built-in ultra-high sensitivity microbalance began recording minute changes in sample mass.

[0127] Throughout the test, the instrument automatically plots the adsorption kinetic curve, which is the curve showing how the amount of adsorbed per unit mass of sample changes over time.

[0128] In surface resistivity and antistatic performance testing, the four-probe method is used to measure surface resistivity. This method uses four equally spaced, linearly arranged metal probes, pressed vertically onto the flat surface of the coating material being tested. During the test, the two outer probes pass a known, stable, small direct current (I) into the material, while the two inner probes measure the voltage drop (V) generated by this current on the material surface. By measuring this voltage and current values, and based on geometric factors such as the probe spacing (s) and the effective thickness of the material, the surface resistivity of the material can be directly calculated using a specific formula. See Tables 1-4 below for details.

[0129] Table 1

[0130] The percentage of boron nitride nanosheets added (%) The percentage of hydrophilic monomer AMPS used (%) Electric field strength (V / mm) for electric field-assisted coating Example 1 20 20 300 Example 2 0 20 300 Example 3 10 20 300 Example 4 30 20 300 Example 5 20 5 300 Example 6 20 10 300 Example 7 20 30 300 Example 8 20 20 0 Example 9 20 20 150 Example 10 20 20 450

[0131] Table 1 is a comparison table of detailed parameters for other embodiments based on Example 1.

[0132] Table 2: Thermal conductivity test

[0133] Thermal conductivity λ⊥ (W / mk) in the thickness direction Local temperature rise ΔT (°C) Example 1 12.5 4.8 Example 2 0.8 18.2 Example 3 5.1 9.5 Example 4 9.7 6.3 Example 5 12.1 5.1 Example 6 12.3 4.9 Example 7 11.8 5.3 Example 8 3.2 12.1 Example 9 8.6 7.2 Example 10 13.8 4.5

[0134] Table 2 shows the test data for thermal conductivity. As can be seen, boron nitride nanosheets (BNNS), as a two-dimensional nanomaterial that is both insulating and thermally conductive, synergistically construct a three-dimensional, interconnected thermally conductive network with reduced graphene oxide. When the material adsorbs moisture and generates adsorption heat, the heat is preferentially conducted rapidly within the BNNS and graphene sheets via phonon vibrations. Especially under the electric field-assisted coating process, BNNS and graphene form an orientation perpendicular to the rotating substrate, efficiently transferring the heat accumulated on the coating surface to the metal rotating substrate, which is then carried away by the airflow passing through the rotating wheel, thus fundamentally preventing localized heat accumulation. Meanwhile, experimental data clearly confirmed this mechanism. In the example without BNNS, the thermal conductivity in the thickness direction was extremely low, resulting in a local temperature rise of up to 18.2℃ during adsorption, which significantly increased the risk of thermal runaway. However, in the example with 20% BNNS, the thermal conductivity jumped to 12.5 W / (mK), and the temperature rise was effectively suppressed to within 5℃, which fully demonstrated the successful construction of the heat conduction network and its role in operational safety.

[0135] Moreover, in the above embodiments, although the graphene network alone has good electrical and thermal conductivity, the layers are prone to direct contact, forming an excessively dense conductive path, resulting in low resistance. This is not only detrimental to linear and stable electrical signal output (for humidity self-monitoring), but may also cause short circuit risk in extreme cases. The addition of BNNS utilizes its insulating properties to physically separate the graphene layers, preventing short circuits in the conductive network. This ensures that the graphene layers can form a continuous conductive network for electrostatic dissipation and signal transmission through tunneling or point contact, without causing uncontrolled resistance due to excessive contact.

[0136] However, when the amount of BNNS added is excessively increased to 30%, although the thermal conductivity is still high, the excessive BNNS significantly increases the viscosity of the composite slurry. During the electric field-assisted coating process, the high viscosity will seriously hinder the free rotation and orientation of the sheet-like nanomaterials, destroy the gradient orientation structure, and make the thermal conductivity slightly lower than that of Example 1.

[0137] More importantly, excessive BNNS over-blocks the graphene sheets, making the conductive network too sparse and resulting in a decrease in surface resistivity. While low resistance is beneficial for static dissipation, it is detrimental to electrical signal monitoring. Furthermore, excessively low resistivity poses a potential risk of leakage or short circuits.

[0138] Table 3: Low-humidity adsorption kinetics test

[0139] Low humidity adsorption response time t (s) Saturated adsorption capacity (g / g) Example 1 65 0.89 Example 2 118 0.85 Example 3 92 0.87 Example 4 105 0.82 Example 5 210 0.65 Example 6 125 0.78 Example 7 58 0.91 Example 8 180 0.88 Example 9 110 0.87 Example 10 70 0.86

[0140] Table 3 shows the low-humidity adsorption kinetics test results. As can be seen from the table, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is a strongly hydrophilic ionic monomer. The sulfonic acid group (-SO3H) in the AMPS molecule has extremely strong polarity and hydration capacity, enabling it to efficiently capture water molecules from the environment through ion-dipole interactions. When the proportion of AMPS in the polymer network is too low, the density of effective strongly hydrophilic adsorption sites inside the material is insufficient. Under low humidity conditions, after water vapor molecules enter the material, there is a lack of sufficient high-energy sites for rapid anchoring and condensation, resulting in slow mass transfer kinetics and adsorption rates within the material. This manifests as a time requirement of up to 210 seconds to reach 63% saturation adsorption capacity, indicating poor adsorption performance and a high adsorption delay.

[0141] With the AMPS ratio increased to 20% as used in Example 1, the density of sulfonic acid groups in the polymer network reaches an ideal state, which can strongly capture low concentrations of water molecules, reducing the humidity threshold for adsorption initiation. More importantly, the adsorbed water molecules can promote the dissociation of sulfonic acid groups to form hydrogen ions. These ions, using adsorbed water as a medium, form highly efficient proton conduction channels within the material. This ion conduction synergistically with the electronic conduction of the graphene network to modulate the material's resistance, enabling humidity changes to be more sensitively converted into electrical signals.

[0142] However, when AMPS is further increased to 30%, although the initial adsorption rate is slightly reduced due to the increase in site density, the excessively high content of hydrophilic groups in the adsorption-desorption cycle, especially from the beginning of moderate humidity, will cause a large number of sulfonic acid groups to rapidly adsorb water, which will cause the material surface or shallow area to reach saturation too early. This will hinder the diffusion of water molecules into the deeper part of the material, affecting the stability of the overall adsorption efficiency and the desorption and regeneration performance.

[0143] Secondly, excessively high AMPS content significantly increases the hydrophilicity of the hydrogel component, leading to a sharp increase in its swelling degree after moisture absorption, thereby generating greater internal stress in the polymer network. This drastic volume change exacerbates the fatigue effect of the material during long-term cyclic use, potentially damaging its structural integrity and durability, and even affecting its bonding strength with the rotor substrate.

[0144] Table 4: Surface resistivity and antistatic properties test

[0145] Surface resistivity ρs (Ω / sq) Maximum static voltage Vmax (V) for triboelectric charging Example 1 <![CDATA[5.2×10 7 ]]> 45 Example 2 <![CDATA[2.5×10 12 ]]> 2850 Example 3 <![CDATA[3.8×10 9 ]]> 650 Example 4 <![CDATA[1.1×10 6 ]]> 18 Example 5 <![CDATA[4.9×10 7 ]]> 48 Example 6 <![CDATA[5.0×10 7 ]]> 43 Example 7 <![CDATA[5.5×10 7 ]]> 45 Example 8 <![CDATA[6.3×10 10 ]]> 520 Example 9 <![CDATA[8.7×10 8 ]]> 180 Example 10 <![CDATA[1.8×10 7 ]]> 29

[0146] Table 4 shows the surface resistivity and antistatic properties. As can be seen from the table, the electric field-assisted coating process is the essence of the functionally graded structure design achieved by this preparation method. Its core mechanism is that the sheet-like nanomaterials in the composite slurry, namely graphene and boron nitride nanosheets, will be polarized under the assistance of a DC electric field, thereby being subjected to a torque that aligns their long axis, i.e., the sheet plane, along the direction of the electric field.

[0147] When an electric field is applied to the upper and lower surfaces of the coated substrate, this force drives the sheet-like materials to align their planes perpendicular to the substrate surface, forming a so-called vertical orientation. Without an electric field, these sheet-like materials are completely randomly distributed and stacked during the drying and curing process. This disordered structure severely hinders the transmission of phonons in the thickness direction, resulting in extremely low thermal conductivity in the vertical direction. Simultaneously, the graphene sheets are mostly in point contact, failing to form a continuous and efficient conductive network within the material's horizontal plane, leading to high surface resistivity and poor electrostatic dissipation.

[0148] As the electric field strength increases, the orientation driving force intensifies. Under the optimal condition of 300 V / mm, the sheet material achieves a highly ordered gradient arrangement. Near the substrate, the material concentration is high and the sheets tend to align horizontally, which facilitates good thermal contact with the metal substrate and the establishment of an in-plane conductive network. From the bottom layer to the surface layer, the material concentration decreases, and the sheets gradually transition to a vertical alignment. The vertically oriented sheets construct rapid heat conduction channels throughout the material's thickness, efficiently dissipating the heat generated by the adsorption reaction and significantly improving the vertical thermal conductivity. Within the horizontal plane, the edge connections and tunneling effect of the sheets form a continuous but non-dense three-dimensional conductive network, ensuring rapid dissipation of static charge while avoiding signal interference or safety hazards that might arise from excessively low resistance.

[0149] However, when the electric field strength is increased excessively to 450 V / mm, the excessively strong orientation force forces most of the sheets to tend to be perfectly vertically aligned. This excessively vertical alignment weakens the connectivity of the sheets in the horizontal plane. Although vertical heat conduction still benefits, the optimization of the horizontal conductive network will reach a plateau or even fluctuate slightly.

[0150] More importantly, an overly ordered and denser arrangement can compress the porous network formed by the polymer matrix, altering the pore structure and pore size distribution within the material, and fine-tuning the mass transfer path of water molecules, especially in low-humidity environments, for gas-phase diffusion.

[0151] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a dehumidifying material for a dehumidifying impeller, characterized in that, Includes the following steps: S1: In the modified graphene oxide dispersion and crosslinking agent mixture, substances with thermosensitive monomers and hydrophilic ionic monomers are added respectively. Under the action of a catalyst, a polymer layer with decreasing crosslinking density from the inside to the outside is formed on the graphene surface. Insulating and thermally conductive materials are added during this process. S2: After S1 polymerization is completed, a reducing agent is added to react, so that reversible covalent bonds are formed between the crosslinking agents. After freeze drying, hybrid foam is obtained. S3: The hybrid foam is immersed in an ethanol solution of a silane coupling agent modified with a 2-ureido-4[1H]-pyrimidinone group to form multilevel reversible hydrogen bonds; S4: The hybrid foam treated by S3 is dispersed in a resin solution and reacted. A thermosensitive phase change material and an epoxy silane coupling agent are added for condensation to obtain a composite slurry with multi-level reversible bonds. S5: The composite slurry is coated onto the rotating wheel under an electric field environment and then cured in stages.

2. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In S1, the modified graphene oxide dispersion is specifically: Silane-Br was added to the graphene oxide dispersion and reacted at 50-70℃ for 10-14h to obtain the modified graphene oxide dispersion, namely the graphene oxide-Br dispersion. The graphene in the graphene oxide dispersion accounts for 4%-6% of the total mass. The insulating and thermally conductive material is selected from one of the layered silicates such as aminated boron nitride nanosheets, aluminum nitride nanosheets, or montmorillonite, and the insulating and thermally conductive material accounts for 15-25% of the mass of the dispersion.

3. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In S1, the crosslinking agent is selected from two combinations of bismaleimide-terminated polyethylene glycol, furfuryl methacrylate, polyisocyanate, or secondary amine-terminated oligomers. The thermosensitive monomer is selected from one of N-isopropylacrylamide, N-vinylcaprolactam, or N-acryloylpyrrolidine; The substance possessing hydrophilic ionic monomers is selected from one of 2-acrylamido-2-methylpropanesulfonic acid, sodium styrene sulfonate, or vinyl sulfonic acid; The molar ratio of the thermosensitive monomer and the hydrophilic ionic monomer is 7-9:2, the crosslinking agent accounts for 5-10% of the total monomer mass, and the molar ratio of the modified graphene oxide dispersion to the thermosensitive monomer is 1:7-9.

4. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In step S2, the reducing agent is selected from ascorbic acid, hydrazine hydrate, or sodium borohydride; the freeze-drying parameters are a temperature of -40 to -70°C, a time of 6-12 hours, and a cooling rate of 1-5°C.

5. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In S3, the concentration of the silane coupling agent with the 2-ureido-4[1H]-pyrimidinone group in ethanol is 0.5-2% w / v; the volume ratio of the solution to the hybrid foam is 3-5:

1.

6. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In S4, the epoxy silane coupling agent is selected from one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propyltriethoxysilane, or 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane. The mass ratio of epoxy silane coupling agent to resin solution is 2-4:

100.

7. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In step S4, the resin solution is selected from one of the following: terminal epoxy hyperbranched polysiloxane resin solution, terminal epoxy hyperbranched polyester resin solution, or terminal vinyl polysiloxane; the mass ratio of the resin solution to the hybrid foam is 1-3:

1.

8. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In step S4, the thermosensitive phase change material is selected from materials whose inner layer is lithium chloride solution, lithium bromide solution or lauric acid and whose outer layer is poly(N-isopropylacrylamide); the thermosensitive phase change material accounts for 8-12% of the mass of the resin solution.

9. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In S5, the electric field is a DC electric field applied to the opposite ends of the rotating wheel, with an electric field strength of 100-500 V / mm, so that the graphene and aminated boron nitride nanosheets undergo orientation changes under the electric field.

10. The method for preparing a dehumidifying material for a dehumidifying impeller according to claim 1, characterized in that: In S5, the staged curing is as follows: UV pre-curing: Apply UV light to the coated composite slurry surface for 25-35 seconds to gel the slurry surface. The first stage of curing takes place at 75-85℃ for 3-5 hours, forming reversible covalent bonds. The second stage of curing involves 1-3 hours at 118-122℃, 1-3 hours at 145-155℃, and 0.5-1.5 hours at 170-190℃. The third stage of curing is carried out at 200-240℃ for 20-40 minutes.

Images