A method for preparing and applying flexible graphene aerogel
By using carboxymethyl cellulose and chitosan crosslinking agents in the preparation of flexible graphene aerogels, the problems of toxic substance residues and poor interfacial compatibility were solved, achieving high biocompatibility and improved mechanical properties, reducing electrical resistance and extending service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG XINCHANGSHUN NEW MATERIAL TECH CO LTD
- Filing Date
- 2025-09-03
- Publication Date
- 2026-05-26
AI Technical Summary
Existing flexible graphene aerogels introduce chemical crosslinking agents during the preparation process, resulting in residual toxic substances, affecting biocompatibility, and are prone to performance degradation with long-term use. Furthermore, the composite polymer materials have poor interfacial compatibility.
Carboxymethyl cellulose was used as a stabilizer to form an ice crystal-graphene composite through an alternating magnetic field and pre-freezing. Chitosan crosslinking agent was used instead of chemical crosslinking agent to prepare flexible graphene aerogels through hydrogen bonding.
It avoids the residue of toxic substances, improves biocompatibility and enhances the mechanical properties of flexible graphene aerogel, reduces contact resistance, increases conductivity, and extends service life.
Smart Images
Figure CN121085257B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flexible graphene aerogel technology, and more particularly to a method for preparing and applying flexible graphene aerogel. Background Technology
[0002] Flexible graphene aerogel, as a novel multifunctional material, combines the high conductivity of graphene with the low density and flexibility of aerogel, showing broad application prospects in fields such as flexible electronics, energy storage, and environmental remediation.
[0003] Currently, in order to improve the mechanical strength of flexible graphene aerogels, traditional methods often introduce chemical cross-linking agents (such as glutaraldehyde). However, residual toxic substances affect biocompatibility. Although composite polymer materials can enhance flexibility, poor interfacial compatibility leads to stress concentration, and long-term use can easily result in performance degradation. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing and applying flexible graphene aerogel, which can avoid the presence of toxic substances during the preparation of flexible graphene aerogel, prevent the impact of residual toxic substances on biocompatibility, and avoid performance degradation of flexible graphene aerogel after long-term use.
[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing flexible graphene aerogel, comprising:
[0006] Graphene nanosheets were dispersed in deionized water to form a dispersion with a concentration of 5-10 mg / mL, and 0.1-0.5 wt% of carboxymethyl cellulose was added as a stabilizer.
[0007] The dispersion was pre-frozen in an alternating magnetic field to form an ice crystal-graphene composite.
[0008] A chitosan crosslinking agent of 1-5 wt% was introduced into the pre-frozen ice crystal-graphene composite, which was then bonded to the oxygen-containing functional groups on the graphene surface via hydrogen bonds to obtain the composite.
[0009] The composite was dried to obtain a flexible graphene aerogel.
[0010] The specific steps of dispersing graphene nanosheets in deionized water to form a dispersion with a concentration of 5-10 mg / mL, and adding 0.1-0.5 wt% carboxymethyl cellulose as a stabilizer include:
[0011] High-purity graphite rods were obtained by pretreating the graphite rod substrate.
[0012] Graphene nanosheets were prepared by immersing high-purity graphite rods as anodes and platinum sheets as cathodes in sodium sulfate electrolyte, applying a DC voltage of 10V, and continuously peeling for 2 hours.
[0013] The exfoliated graphene nanosheets were dispersed in deionized water at a concentration of 5-10 mg / mL and ultrasonically treated for 30 minutes.
[0014] Add 0.1-0.5 wt% carboxymethyl cellulose and mechanically stir at 500 rpm for 2 hours to form a stable dispersion.
[0015] The specific steps for pretreating the graphite rod substrate to obtain high-purity graphite rods include:
[0016] The graphite rod substrate was sequentially immersed in deionized water and anhydrous ethanol, and ultrasonically cleaned for 15 minutes each to remove surface dust, organic matter and metal impurities.
[0017] Use 600-grit sandpaper to evenly polish along the axis of the graphite rod to form periodic grooves;
[0018] The graphite rod was placed in a tube furnace and heated to 300°C at a rate of 5°C / min under an argon atmosphere. The temperature was held for 2 hours and then allowed to cool naturally to room temperature.
[0019] Graphite rods were immersed in a 5% nitric acid solution and soaked at room temperature for 30 minutes. They were then rinsed with deionized water until neutral to obtain high-purity graphite rods.
[0020] In the step of pre-freezing the dispersion in an alternating magnetic field to form an ice crystal-graphene composite,
[0021] The magnetic field direction is perpendicular to the pre-freezing direction, the frequency of the alternating magnetic field is 10-100Hz, and the field strength is 0.1-0.5T.
[0022] The specific steps for preparing the composite by introducing 1-5 wt% chitosan crosslinking agent into the pre-frozen ice crystal-graphene composite and binding it with oxygen-containing functional groups on the graphene surface via hydrogen bonds include:
[0023] Dissolve 1-5 wt% chitosan in 1% acetic acid solution and stir mechanically until completely dissolved to obtain a chitosan solution;
[0024] The pre-frozen ice crystal-graphene composite was immersed in a chitosan solution and reacted at -20°C for 12 hours to obtain the composite.
[0025] The specific steps for drying the composite to obtain flexible graphene aerogel include:
[0026] The composite was placed in a vacuum drying oven and pre-dried for 2 hours under a pressure of 10 Pa and a temperature of -50 °C.
[0027] The composite was subjected to gradient temperature drying by heating the vacuum drying oven to -20°C at a rate of 1°C / min, holding for 1 hour, then heating to 0°C and holding for 2 hours.
[0028] The composite was vacuum dried at 25°C and 1 Pa for 12 hours to completely remove residual moisture, thus obtaining flexible graphene aerogel.
[0029] Secondly, the present invention also provides an application of flexible graphene aerogel, wherein the flexible graphene aerogel prepared by the aforementioned method is characterized in that the flexible graphene aerogel is applied to a conductive substrate of flexible electronic devices.
[0030] This invention discloses a method for preparing and applying flexible graphene aerogel. Through magnetic field coupling with pre-freezing, graphene sheets are induced to align and form a layered structure (longitudinal). Simultaneously, ice crystals sublimate to form a network of pores (transverse), achieving a synergistic improvement in longitudinal compressive modulus ≥30 kPa and transverse bending radius ≤5 mm. The ice crystal growth rate is synergistically controlled by temperature gradient (≤1 mm / min) and magnetic field parameters (frequency 10-100 Hz, field strength 0.1-0.5 T). The pore size distribution is concentrated (50-200 μm), wall thickness uniformity is improved by 40%, contact resistance is significantly reduced, and conductivity reaches 10⁻⁶. 3 S / m. Chitosan (degree of deacetylation ≥85%) is used to replace chemical crosslinking agents (such as glutaraldehyde) to avoid toxic residues. Cytotoxicity tests (ISO 10993-5) show a 90% improvement in biocompatibility. This can avoid toxic residues during the preparation of flexible graphene aerogels, prevent residual toxic substances from affecting biocompatibility, and avoid performance degradation of flexible graphene aerogels during long-term use. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0032] Figure 1 This is a flowchart of the preparation method of the flexible graphene aerogel of the present invention.
[0033] Figure 2 This is a flowchart of the present invention, which describes the process of dispersing graphene nanosheets in deionized water to form a dispersion with a concentration of 5-10 mg / mL, and adding 0.1-0.5 wt% carboxymethyl cellulose as a stabilizer.
[0034] Figure 3 This is a flowchart of the process of pretreating a graphite rod substrate to obtain a high-purity graphite rod according to the present invention.
[0035] Figure 4 The flowchart of the present invention describes the process of introducing 1-5 wt% chitosan crosslinking agent into a pre-frozen ice crystal-graphene composite, which binds to oxygen-containing functional groups on the graphene surface through hydrogen bonds to obtain the composite.
[0036] Figure 5 This is a flowchart of the process of drying the composite to obtain flexible graphene aerogel according to the present invention. Detailed Implementation
[0037] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.
[0038] Firstly, please refer to Figures 1-5 ,in, Figure 1 This is a flowchart of the preparation method of the flexible graphene aerogel of the present invention. Figure 2 This is a flowchart of the present invention, which describes the process of dispersing graphene nanosheets in deionized water to form a dispersion with a concentration of 5-10 mg / mL, and adding 0.1-0.5 wt% carboxymethyl cellulose as a stabilizer. Figure 3 This is a flowchart of the process of pretreating a graphite rod substrate to obtain a high-purity graphite rod according to the present invention. Figure 4 The flowchart of the present invention describes the process of introducing 1-5 wt% chitosan crosslinking agent into a pre-frozen ice crystal-graphene composite, which binds to oxygen-containing functional groups on the graphene surface through hydrogen bonds to obtain the composite. Figure 5 This is a flowchart of the process of drying the composite to obtain flexible graphene aerogel according to the present invention.
[0039] This invention provides a method for preparing flexible graphene aerogel, comprising:
[0040] S1 disperses graphene nanosheets in deionized water to form a dispersion with a concentration of 5-10 mg / mL, and adds 0.1-0.5 wt% carboxymethyl cellulose as a stabilizer.
[0041] The specific steps include:
[0042] S11 is used to pretreat graphite rod substrate to obtain high-purity graphite rods.
[0043] The specific steps include:
[0044] S111 The graphite rod substrate is sequentially immersed in deionized water and anhydrous ethanol, and ultrasonically cleaned for 15 minutes each to remove surface dust, organic matter and metal impurities.
[0045] In this step, the graphite rod is sequentially immersed in deionized water and anhydrous ethanol, and ultrasonically cleaned (frequency 40kHz, power 200W) for 15 minutes each time to remove surface dust, organic matter, and metallic impurities. This prevents contaminants from causing side reactions (such as localized overheating and bubble formation) during electrolysis and ensures uniform contact between the electrolyte and the graphite surface.
[0046] S112 is uniformly polished along the axis of the graphite rod using 600-grit sandpaper to form periodic grooves;
[0047] In this step, the graphite rod is uniformly polished along its axial direction using 600-grit sandpaper to form periodic grooves (5-10 μm deep, 50 μm spacing). This increases the surface roughness of the graphite, improves the electrolyte penetration efficiency, and promotes the uniformity of the graphite intercalation reaction.
[0048] S113 placed the graphite rod in a tube furnace, heated it to 300°C at 5°C / min under an argon atmosphere, held it at that temperature for 2 hours, and then naturally cooled it to room temperature.
[0049] This step removes the moisture and volatile organic compounds adsorbed inside the graphite to prevent uneven peeling or increased graphene defects caused by gas release during electrolysis.
[0050] S114 involves immersing graphite rods in a 5% nitric acid solution for 30 minutes at room temperature, followed by rinsing with deionized water until neutral to obtain high-purity graphite rods.
[0051] In this step, oxygen-containing functional groups (such as -OH and -COOH) are introduced into the graphite surface through slight oxidation, enhancing the interfacial wettability between the electrolyte and graphite. After three pretreatment steps—cleaning, roughening, and heat treatment—the graphene yield increased from 8% of the original graphite rod to 18%.
[0052] S12 uses high-purity graphite rods as anodes and platinum sheets as cathodes, immerses them in sodium sulfate electrolyte, applies a DC voltage of 10V, and continuously exfoliates for 2 hours to obtain graphene nanosheets.
[0053] In this step, analytical grade sodium sulfate (purity ≥99%) is dissolved in deionized water and magnetically stirred (500 rpm) for 30 minutes until completely dissolved. The sodium sulfate (Na2SO4) aqueous solution serves as the conductive medium. A high-purity graphite rod (6 mm in diameter and 10 cm in length) is used as the graphene exfoliation source. A platinum sheet (2 × 2 cm in size and 99.9% purity) serves as the counter electrode. The two electrodes are placed parallel to each other with a 2 cm gap and immersed in the electrolyte, ensuring that the anode is completely submerged. A DC voltage of 10 V is applied, and the electrolyte temperature is maintained at 25 ± 1 °C. Exfoliation is continued for 2 hours. During the electrolysis process, the graphite rod is oxidized, and the surface layered structure is intercalated, generating CO2 gas, which leads to the exfoliation of the graphite sheets, thus obtaining graphene nanosheets.
[0054] S13: The exfoliated graphene nanosheets were dispersed in deionized water at a concentration of 5-10 mg / mL and ultrasonically treated for 30 minutes.
[0055] In this step, ultrasonic treatment ensures uniform dispersion of graphene, providing a basis for subsequent magnetic field-oriented assembly.
[0056] Add 0.1-0.5 wt% carboxymethyl cellulose to S14 and mechanically stir at 500 rpm for 2 hours to form a stable dispersion.
[0057] In this step, 0.1-0.5 wt% carboxymethyl cellulose (CMC) is added. CMC prevents graphene agglomeration through electrostatic repulsion, replacing traditional surfactants (such as SDS).
[0058] S2 places the dispersion in an alternating magnetic field for pre-freezing to form an ice crystal-graphene composite;
[0059] In this step, the magnetic field direction is perpendicular to the pre-freezing direction, the frequency of the alternating magnetic field is 10-100Hz, and the field strength is 0.1-0.5T. Specifically, the dispersion is injected into a polytetrafluoroethylene mold (10×10×2cm) and placed on a programmable freezing stage (temperature gradient -20℃ to -80℃). The pre-freezing direction is perpendicular to the magnetic field direction to provide a temperature gradient for the directional growth of ice crystals. The alternating magnetic field generator (frequency 10-100Hz, field strength 0.1-0.5T) is activated, with the magnetic field direction forming a 90° angle with the pre-freezing direction. The magnetic field induces the graphene sheets to align along the magnetic field direction, forming a layered structure; ice crystals grow along the temperature gradient direction, compressing the interlayers of graphene to form a network of pores. The magnetic field and freezing conditions are maintained for 2 hours. After the dispersion is completely frozen, the magnetic field is turned off and the frozen state is maintained for 12 hours. The temperature distribution is monitored in real time using an infrared thermal imager to ensure that the ice crystal growth rate is ≤1mm / min.
[0060] S3 introduces 1-5 wt% chitosan crosslinking agent into the pre-frozen ice crystal-graphene composite, which binds to the oxygen-containing functional groups on the graphene surface through hydrogen bonds to obtain the composite.
[0061] The specific steps include:
[0062] S31 Dissolves 1-5 wt% chitosan in 1% acetic acid solution and mechanically stirs for 4 hours until completely dissolved to obtain chitosan solution;
[0063] In this step, 1-5 wt% chitosan (degree of deacetylation ≥ 85%) is dissolved in 1% acetic acid solution and mechanically stirred (800 rpm) for 4 hours until completely dissolved; chitosan serves as a green crosslinking agent, replacing glutaraldehyde in the traditional preparation method.
[0064] S32 immerses the pre-frozen ice crystal-graphene composite into a chitosan solution and reacts it at -20°C for 12 hours to obtain the composite.
[0065] In this step, the amino groups of chitosan are bonded to the carboxyl groups on the graphene surface through hydrogen bonds, forming a cross-linked network.
[0066] S4 was used to dry the composite to obtain flexible graphene aerogel.
[0067] The specific steps include:
[0068] S41 placed the composite in a vacuum drying oven and pre-dried it for 2 hours under a pressure of 10 Pa and a temperature of -50 °C.
[0069] In this step, moisture is removed from the surface of the composite to prevent rapid sublimation of ice crystals from causing pore collapse.
[0070] S42 heats the vacuum drying oven to -20°C at a rate of 1°C / min, holds for 1 hour, then heats it to 0°C and holds for 2 hours to perform gradient temperature drying on the composite.
[0071] In this step, the ice crystal sublimation rate is controlled by gradient heating of the composite to avoid damage to the pore structure.
[0072] S43 vacuum-drying the composite at 25℃ and 1Pa for 12 hours completely removes residual moisture, thus obtaining flexible graphene aerogel.
[0073] The method for preparing flexible graphene aerogel of this invention induces graphene sheets to align and form a layered structure (longitudinal) through magnetic field coupling with pre-freezing. Simultaneously, ice crystals sublimate to form a network of pores (transverse), achieving a synergistic improvement in longitudinal compressive modulus ≥30 kPa and transverse bending radius ≤5 mm. The ice crystal growth rate is synergistically controlled by temperature gradient (≤1 mm / min) and magnetic field parameters (frequency 10-100 Hz, field strength 0.1-0.5 T), resulting in concentrated pore size distribution (50-200 μm), improved wall thickness uniformity by 40%, significantly reduced contact resistance, and conductivity reaching 10-1. 3 S / m. Chitosan (degree of deacetylation ≥85%) is used to replace chemical crosslinking agents (such as glutaraldehyde) to avoid toxic residues. Cytotoxicity tests (ISO 10993-5) show a 90% improvement in biocompatibility. This can avoid toxic residues during the preparation of flexible graphene aerogels, prevent residual toxic substances from affecting biocompatibility, and avoid performance degradation of flexible graphene aerogels during long-term use.
[0074] Secondly, the present invention also provides an application of flexible graphene aerogel, wherein the flexible graphene aerogel prepared by the aforementioned method is characterized in that the flexible graphene aerogel is applied to a conductive substrate of flexible electronic devices.
[0075] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.
Claims
1. A method for preparing flexible graphene aerogel, characterized in that, Includes the following steps: The graphite rod substrate was sequentially immersed in deionized water and anhydrous ethanol, and ultrasonically cleaned for 15 minutes each to remove surface dust, organic matter, and metallic impurities. The graphite rod was then uniformly polished along its axial direction with 600-grit sandpaper to form periodic grooves 5-10 μm deep and 50 μm apart. The graphite rod was placed in a tube furnace and heated to 300°C at 5°C / min under an argon atmosphere, held at that temperature for 2 hours, and then allowed to cool naturally to room temperature. Finally, the graphite rod was immersed in a 5% nitric acid solution at room temperature for 30 minutes, and then rinsed with deionized water until neutral to obtain a high-purity graphite rod. Graphene nanosheets were prepared by immersing high-purity graphite rods as anodes and platinum sheets as cathodes in sodium sulfate electrolyte, applying a DC voltage of 10V, and continuously peeling for 2 hours. The exfoliated graphene nanosheets were dispersed in deionized water at a concentration of 5-10 mg / mL, sonicated for 30 minutes, and then 0.1-0.5 wt% carboxymethyl cellulose was added. The mixture was mechanically stirred at 500 rpm for 2 hours to form a stable dispersion. The dispersion was injected into a polytetrafluoroethylene mold and placed on a programmable freezing stage. The pre-freezing temperature gradient was -20°C to -80°C. An alternating magnetic field generator was started, with the magnetic field direction perpendicular to the pre-freezing direction. The frequency of the alternating magnetic field was 10-100Hz and the field strength was 0.1-0.5T. The temperature distribution was monitored in real time using an infrared thermal imager to ensure that the ice crystal growth rate was ≤1mm / min. The magnetic field and freezing conditions were maintained for 2 hours. After the dispersion was completely frozen, the magnetic field was turned off and the frozen state was maintained for 12 hours to form an ice crystal-graphene composite. Chitosan with a degree of deacetylation ≥85% was dissolved in 1% acetic acid solution at a concentration of 1-5 wt%, and mechanically stirred for 4 hours until completely dissolved to obtain a chitosan solution; the pre-frozen ice crystal-graphene composite was immersed in the chitosan solution and reacted in a -20°C environment for 12 hours, so that the amino groups of chitosan and the carboxyl groups on the surface of graphene were combined through hydrogen bonds to form a cross-linked network, thus obtaining the composite; The composite was placed in a vacuum drying oven and pre-dried for 2 hours at a pressure of 10 Pa and a temperature of -50°C. The vacuum drying oven was then heated to -20°C at a rate of 1°C / min and held for 1 hour, and then heated to 0°C and held for 2 hours. Finally, the composite was vacuum dried at 25°C and 1 Pa for 12 hours to completely remove residual moisture, thus obtaining flexible graphene aerogel.
2. A flexible graphene aerogel, prepared by the method of claim 1, characterized in that, The aerogel has a longitudinal framework with oriented, layered structures and a transverse framework with a network of pores formed by the sublimation of ice crystals. Its longitudinal compressive modulus is ≥30 kPa, its transverse bending radius is ≤5 mm, and its electrical conductivity reaches 10. 3 S / m.