Graphene-pbat composite aerogel and preparation method thereof

Abstract

This application provides a graphene-PBAT composite aerogel and its preparation method, belonging to the fields of biodegradable materials and aerogel technology. The method includes the following steps: preparing a graphene oxide dispersion; adding an amphoteric surfactant to the graphene oxide dispersion, stirring until homogeneous, filtering, washing, and freeze-drying to obtain modified graphene oxide; using 1,4-dioxane as a solvent to completely dissolve PBAT in 1,4-dioxane to obtain a PBAT solution; adding the modified graphene oxide to the PBAT solution and ultrasonically dispersing until homogeneous for liquid-phase composite formation; after liquid-phase composite formation, adding deionized water, stirring until homogeneous, pouring into a mold, pre-freezing, and then freeze-drying. The composite aerogel of this application has characteristics such as high specific surface area, large porosity, and low density; the composite with modified graphene enhances the mechanical properties of PBAT, improving the problems of low strength, poor weather resistance, and low modulus of PBAT, thus enabling the final composite aerogel to have a wider range of applications.

Description

Technical Field

[0001] This application belongs to the field of biodegradable materials and aerogel technology, and more specifically, relates to a graphene-PBAT composite aerogel and its preparation method. Background Technology

[0002] Aerogels are nanoscale porous solid materials formed by replacing the liquid phase in a gel with gas through a sol-gel method and a specific drying process. They are characterized by high porosity (>90%), low density, and high specific surface area. These properties give aerogel materials excellent thermal insulation properties, demonstrating superior performance in photoelectrocatalysis, adsorption separation, and thermal insulation. With the development of different types of gel synthesis and drying technologies, the variety of aerogel materials has become increasingly rich, and they are widely used in thermal, optical, acoustic, electrical, and adsorption catalysis fields. However, current research on aerogels faces several challenges: First, the preparation process of most aerogel materials is complex and costly; second, many aerogels are non-degradable, posing significant challenges to subsequent waste disposal and causing secondary pollution to the environment.

[0003] Patent CN114085418A discloses a biodegradable, highly hydrophobic aerogel porous material and its preparation method, mainly using a combination of L-polylactic acid and D-polylactic acid to prepare the biodegradable aerogel. However, polylactic acid itself is brittle and has poor elongation at break and toughness, which limits the mechanical properties of the prepared aerogel material; at the same time, toxic reagents such as chloroform are used in the entire preparation process, which will cause environmental harm during waste liquid treatment.

[0004] Patent CN116102766A discloses an ultralight, highly flame-retardant, biodegradable PLA foam and its preparation process. The process mainly involves compounding RDP, lignin, APP, and silica aerogel to obtain a flame-retardant system, which is then mixed with PLA, PBAT, and an epoxy chain extender before being supercritically foamed to prepare the foam material. The preparation process involves multiple systems and a large number of substances, resulting in complex reactions and difficult-to-control interfacial interactions between different substances.

[0005] Polybutylene adipate / terephthalate (PBAT) is a synthetic aliphatic-aromatic copolyester that degrades completely within weeks under the action of naturally occurring enzymes in fertile soil. PBAT possesses both the biodegradability of aliphatic polyesters and the excellent mechanical properties of aromatic polyesters: good ductility, elongation at break, heat resistance, and impact resistance, while also exhibiting excellent biodegradability. It is one of the most actively researched and commercially successful biodegradable materials in biodegradable plastics. However, PBAT suffers from poor crystallinity, low melt strength, and high price, limiting its application in many fields. Therefore, PBAT needs to be modified and strengthened to improve its overall performance. Graphene possesses excellent mechanical strength, electrical conductivity, high specific surface area, and high thermal stability; its polymer nanocomposites often show significant performance improvements even at low addition levels. Modifying PBAT using graphene as a functional material can effectively improve its mechanical properties and realize its functional applications. However, commonly used graphene oxide is hydrophilic and oleophobic, and cannot be uniformly dispersed in common organic reagents. Therefore, it cannot be liquid-phase composited with PBAT, and further cannot be used to prepare graphene composite biodegradable material aerogels. Summary of the Invention

[0006] The purpose of this application is to provide a graphene-PBAT composite aerogel and its preparation method to improve the strength, weather resistance and modulus of PBAT materials.

[0007] To achieve the above objectives, the first aspect of this application provides a method for preparing a graphene-PBAT composite aerogel. This method first uses an environmentally friendly amphoteric surfactant to rapidly modify graphene oxide. The amphoteric surfactant rapidly modifies the surface of graphene oxide through hydrogen bonding and electrostatic interactions. The modified graphene oxide loses its hydrophilicity and acquires excellent oleophilicity, providing the necessary conditions for subsequent liquid-phase composite formation. Then, a relatively environmentally friendly 1,4-dioxane is selected as the solvent to perform liquid-phase composite formation of the modified graphene oxide and the biodegradable material PBAT. After composite formation, a certain amount of deionized water is added for pre-freezing treatment. Water-assisted thermally induced phase separation is then performed, followed by freeze-drying to obtain a graphene composite biodegradable aerogel with a rich porous structure. Specifically, the method includes the following steps:

[0008] S1. Preparation of graphene oxide dispersion;

[0009] S2. Add an amphoteric surfactant to the graphene oxide dispersion, stir until homogeneous, filter, wash, and freeze-dry to obtain modified graphene oxide.

[0010] S3. Using 1,4-dioxane as a solvent, completely dissolve PBAT in 1,4-dioxane to obtain a PBAT solution.

[0011] S4. The modified graphene oxide is added to the PBAT solution and ultrasonically dispersed evenly to perform liquid-phase composite.

[0012] S5. After the liquid phase composite is completed, deionized water is added, stirred evenly, poured into a mold, pre-frozen, and then freeze-dried to obtain graphene-PBAT composite aerogel.

[0013] Furthermore, the amphoteric surfactant is one or more of lauramidopropylamine oxide (LAO), cocamidopropylamine oxide (CAO), octadecanoamide propylamine oxide, OAE-18, and OAE-14.

[0014] Furthermore, in step S3, the biodegradable material PBAT is completely dissolved in 1,4-dioxane by water bath heating and mechanical stirring, with a stirring rate of 300-600 rpm and a temperature of 40-50°C.

[0015] Further, in step S4, the mass ratio of the modified graphene oxide to the PBAT is 1 to 3:100.

[0016] Furthermore, in step S4, each ultrasound session lasts 1 minute, and a total of 5 ultrasound sessions are performed.

[0017] Furthermore, in the PBAT solution, the weight percentage of PBAT is 6wt% to 8wt%.

[0018] Further, in step S4, the modified graphene oxide has a weight percentage of 0.14 wt% to 0.18 wt%.

[0019] Furthermore, the temperature for liquid-phase mixing is 40–50°C. The stirring rate for liquid-phase mixing is 300–600 rpm.

[0020] Furthermore, the pre-freezing treatment temperature is -10 to -20°C, and the treatment time is 12 to 24 hours.

[0021] Furthermore, the freeze-drying temperature is -40 to -50°C, the vacuum degree is 1 to 10 Pa, and the time is 24 to 36 hours.

[0022] Furthermore, the graphene oxide dispersion was prepared by a modified Hummers method.

[0023] In a second aspect, this application provides a graphene-PBAT composite aerogel, obtained by any of the preparation methods described above.

[0024] Compared with the prior art, this application has the following technical effects:

[0025] The method for preparing a graphene-PBAT composite aerogel disclosed in this application first involves rapidly alkylating graphene oxide (GO) with an environmentally friendly amphoteric surfactant: the O atoms in the abundant oxygen-containing functional groups (hydroxyl and carboxyl groups) on the GO surface combine with the N atoms of the amine oxide groups in the amphoteric surfactant through electrostatic interactions in water (O... - With N + and COO - With N + Furthermore, hydrogen bonds are formed between the O atoms and the amphoteric surfactant molecules, further stabilizing the grafting of amphoteric surfactant molecules onto the GO surface. The graphene modified by non-covalent grafting loses its hydrophilicity, while the long alkyl chains of the grafted amphoteric surfactant molecules endow it with excellent lipophilicity, thus providing the necessary conditions for subsequent liquid-phase composite with the biodegradable material PBAT in organic solvents.

[0026] The obtained modified graphene oxide (MGO) was then combined with PBAT in a liquid phase in a 1,4-dioxane system. Under specific reaction temperatures and rotation speeds, MGO and PBAT molecules were uniformly combined in the solvent. Simultaneously, the alkyl long chains grafted onto the MGO surface intertwined with the PBAT molecules, forming physical cross-links. Meanwhile, the free nitrogen atoms on the MGO surface... + It also combines with the terminal hydroxyl and carboxyl groups in the PBAT molecular chain to form chemical cross-links. MGO combines with PBAT molecules through physical and chemical cross-linking, effectively improving the problems of low strength, poor weather resistance, and low modulus of PBAT.

[0027] Finally, a simple water-assisted thermally induced phase separation (TIPS) method was used to prepare the composite aerogel: a certain amount of deionized water was directly added to the system after liquid-phase composite, mixed evenly, and then placed in a refrigerator for pre-freezing. The solvent is the dispersed phase, and due to its low freezing point (12℃), 1,4-dioxane is pre-frozen first, inducing phase separation. The system gradually separates into a polymer-rich phase and a polymer-poor phase. In the polymer-rich phase, the polymer is a continuous phase that freezes, and its volume gradually increases as the temperature decreases (forming a larger porous structure after freeze-drying). When the temperature drops to 0℃, the water begins to freeze, but due to its small quantity, most of the water can only form small pores (forming a smaller porous structure after freeze-drying). Finally, the solvent and deionized water are removed by freeze-drying to obtain the graphene composite biodegradable material aerogel.

[0028] The graphene-PBAT composite aerogel prepared in this application possesses abundant three-dimensional porous structure, high specific surface area, large porosity, and low density. The modified graphene composite enhances the mechanical properties of the biodegradable material PBAT, improving its low strength, poor weather resistance, and low modulus, thus broadening the application scope of the final composite aerogel. Furthermore, the main component of this composite aerogel is the biodegradable material PBAT, and all raw materials used in its preparation are environmentally friendly, capable of natural degradation after disposal and posing no harm to the environment. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, 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 of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 SEM image of the biodegradable aerogel prepared in Comparative Example 1 of this application;

[0031] Figure 2 SEM image of the biodegradable aerogel prepared in Comparative Example 2 of this application;

[0032] Figure 3 This is a SEM image of the graphene-PBAT composite aerogel prepared in Example 1 of this application;

[0033] Figure 4 This is a SEM image of the graphene-PBAT composite aerogel prepared in Example 2 of this application;

[0034] Figure 5 This is a SEM image of the graphene-PBAT composite aerogel prepared in Example 3 of this application;

[0035] Figure 6 A photograph (left) of the graphene-PBAT composite aerogel prepared in Example 1 of this application and a comparison photograph (right) of the sample before and after compression. Detailed Implementation

[0036] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0038] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0039] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0040] Example 1

[0041] Example 1 of this application provides a graphene-PBAT composite aerogel and its preparation method, including the following steps:

[0042] (1) A uniformly dispersed graphene oxide solution was prepared using the improved Hummers method. The specific preparation process was referred to in the doctoral dissertation "Preparation and characterization of polyolefin-based graphene oxide composite materials" from Lanzhou University.

[0043] (2) Dissolve 75g of lauramidopropylamine oxide in 300mL of water and slowly add it dropwise to the graphene oxide solution in step (1). The mass ratio of lauramidopropylamine oxide to graphene oxide is 1:1. Stir rapidly at a speed of 400rpm, then filter, wash, freeze dry to obtain modified graphene oxide with oleophilic properties.

[0044] (3) The PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm.

[0045] (4) The modified graphene oxide from step (2) was ultrasonically dispersed in 1,4-dioxane for 1 min each time, for a total of 5 times; the modified graphene oxide solution after complete ultrasonic dispersion was added to the mixed solution after complete dissolution of PBAT from step (3), and the temperature and stirring rate were kept constant, and the liquid phase composite reaction was carried out for 3 h; the ratio of PBAT, modified graphene oxide, and 1,4-dioxane (total amount) was 1.5 g: 0.045 g: 50 mL;

[0046] (5) After the liquid phase composite is completed, the mixed solution is transferred to a refrigerator at -18℃ for pre-freezing treatment for 24h; the pre-frozen sample is transferred to a freeze dryer and freeze-dried at 7Pa and -50℃ for 36h to obtain graphene-PBAT composite aerogel.

[0047] Example 2

[0048] Example 2 of this application provides a graphene-PBAT composite aerogel and its preparation method, including the following steps:

[0049] (1) Prepare modified graphene oxide with lipophilic properties. The specific preparation process is described in Example 1.

[0050] (2) The PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm.

[0051] (3) The modified graphene oxide from step (1) was ultrasonically dispersed in 1,4-dioxane for 1 min each time, for a total of 5 times; the modified graphene oxide solution after complete ultrasonic dispersion was added to the mixed solution after complete dissolution of PBAT from step (2), and the temperature and stirring rate were kept constant, and the liquid phase composite reaction was carried out for 3 h; the ratio of PBAT, modified graphene oxide, and 1,4-dioxane (total amount) was 1.5 g: 0.045 g: 50 mL;

[0052] (4) Add 2 mL of deionized water to the solution after complete liquid-phase composite, disperse evenly, and transfer the mixed solution to a refrigerator at -18℃ for pre-freezing treatment for 24 h; transfer the pre-frozen sample to a freeze dryer and freeze-dry at 7 Pa and -50℃ for 36 h to obtain graphene-PBAT composite aerogel.

[0053] Example 3

[0054] Example 3 of this application provides a graphene-PBAT composite aerogel and its preparation method, including the following steps:

[0055] (1) Prepare modified graphene oxide with lipophilic properties. The specific preparation process is described in Example 1.

[0056] (2) The PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm.

[0057] (3) The modified graphene oxide from step (1) was ultrasonically dispersed in 1,4-dioxane for 1 min each time, for a total of 5 times; the modified graphene oxide solution after complete ultrasonic dispersion was added to the mixed solution after complete dissolution of PBAT from step (2), and the temperature and stirring rate were kept constant, and the liquid phase composite reaction was carried out for 3 h; the ratio of PBAT, modified graphene oxide, and 1,4-dioxane (total amount) was 1.5 g: 0.045 g: 50 mL;

[0058] (4) Add 4 mL of deionized water to the solution after complete liquid-phase composite, disperse evenly, and transfer the mixed solution to a refrigerator at -18℃ for pre-freezing treatment for 24 h; transfer the pre-freezed sample to a freeze dryer and freeze-dry at 7 Pa and -50℃ for 36 h to obtain graphene-PBAT composite aerogel.

[0059] Example 4

[0060] Example 4 of this application provides a graphene-PBAT composite aerogel and its preparation method, including the following steps:

[0061] (1) Prepare modified graphene oxide with lipophilic properties. The specific preparation process is described in Example 1.

[0062] (2) The PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm.

[0063] (3) The modified graphene oxide from step (1) was ultrasonically dispersed in 1,4-dioxane for 1 min each time, for a total of 5 times; the modified graphene oxide solution after complete ultrasonic dispersion was added to the mixed solution after complete dissolution of PBAT from step (2), and the temperature and stirring rate were kept constant, and the liquid phase composite reaction was carried out for 3 h; the ratio of PBAT, modified graphene oxide, and 1,4-dioxane (total amount) was 1.5 g: 0.015 g: 50 mL;

[0064] (4) After the liquid phase composite is completely combined, the mixed solution is transferred to a refrigerator at -18℃ for pre-freezing treatment for 24h; the pre-frozen sample is transferred to a freeze dryer and freeze-dried at 7Pa and -50℃ for 36h to obtain graphene-PBAT composite aerogel.

[0065] Example 5

[0066] Example 5 of this application provides a graphene-PBAT composite aerogel and its preparation method, including the following steps:

[0067] (1) Prepare modified graphene oxide with lipophilic properties. The specific preparation process is described in Example 1.

[0068] (2) The PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm.

[0069] (3) The modified graphene oxide from step (1) was ultrasonically dispersed in 1,4-dioxane for 1 min each time, for a total of 5 times; the modified graphene oxide solution after complete ultrasonic dispersion was added to the mixed solution after complete dissolution of PBAT from step (2), and the temperature and stirring rate were kept constant, and the liquid phase composite reaction was carried out for 3 h; the ratio of PBAT, modified graphene oxide, and 1,4-dioxane (total amount) was 1.5 g: 0.015 g: 50 mL;

[0070] (4) Add 2 mL of deionized water to the solution after complete liquid-phase composite, disperse evenly, and transfer the mixed solution to a refrigerator at -18℃ for pre-freezing treatment for 24 h; transfer the pre-frozen sample to a freeze dryer and freeze-dry at 7 Pa and -50℃ for 36 h to obtain graphene-PBAT composite aerogel.

[0071] Example 6

[0072] Example 6 of this application provides a graphene-PBAT composite aerogel and its preparation method, including the following steps:

[0073] (1) Prepare modified graphene oxide with lipophilic properties. The specific preparation process is described in Example 1.

[0074] (2) The PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm.

[0075] (3) The modified graphene oxide from step (1) was ultrasonically dispersed in 1,4-dioxane for 1 min each time, for a total of 5 times; the modified graphene oxide solution after complete ultrasonic dispersion was added to the mixed solution after complete dissolution of PBAT from step (2), and the temperature and stirring rate were kept constant, and the liquid phase composite reaction was carried out for 3 h; the ratio of PBAT, modified graphene oxide, and 1,4-dioxane (total amount) was 1.5 g: 0.015 g: 50 mL;

[0076] (4) Add 4 mL of deionized water to the solution after complete liquid-phase composite, disperse evenly, and transfer the mixed solution to a refrigerator at -18℃ for pre-freezing treatment for 24 h; transfer the pre-freezed sample to a freeze dryer and freeze-dry at 7 Pa and -50℃ for 36 h to obtain graphene-PBAT composite aerogel.

[0077] Comparative Example 1

[0078] PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm, with a PBAT to 1,4-dioxane ratio of 1.5g:50mL. The completely dissolved mixture was transferred to a freezer at -18℃ for pre-freezing for 24h. The pre-frozen sample was then transferred to a freeze dryer and freeze-dried at 7Pa and -50℃ for 36h to obtain a pure biodegradable aerogel.

[0079] Comparative Example 2

[0080] PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm, with a PBAT to 1,4-dioxane ratio of 1.5g:50mL. 2mL of deionized water was added dropwise to the completely dissolved solution, and after uniform dispersion, the mixture was transferred to a freezer at -18℃ for pre-freezing for 24h. The pre-frozen sample was then transferred to a freeze dryer and freeze-dried at 7Pa and -50℃ for 36h to obtain a pure biodegradable aerogel.

[0081] Comparative Example 3

[0082] PBAT masterbatch was completely dissolved in 1,4-dioxane at a water bath temperature of 45℃ and a stirring speed of 500rpm, with a PBAT to 1,4-dioxane ratio of 1.5g:50mL. 4mL of deionized water was added dropwise to the completely dissolved solution, and after uniform dispersion, the mixed solution was transferred to a freezer at -18℃ for pre-freezing for 24h. The pre-frozen sample was transferred to a freeze dryer and freeze-dried at 7Pa and -50℃ for 36h to obtain pure biodegradable aerogel.

[0083] Figure 1 This is a SEM image of the biodegradable aerogel prepared in Comparative Example 1 of this application. Figure 1 It can be seen that the pore wall structure of the aerogel material prepared without adding a pore-forming agent is relatively smooth.

[0084] Figure 2 This is a SEM image of the biodegradable aerogel prepared in Comparative Example 2 of this application. Figure 2 It can be seen that the aerogel material prepared by adding the pore-forming agent has a porous structure on the pore wall.

[0085] Figure 3 This is a SEM image of the graphene-PBAT composite aerogel prepared in Example 1 of this application. Figure 3 It can be seen that the aerogel material with graphene composite has a richer pore structure; the pore wall structure of the graphene composite aerogel material prepared without adding pore-forming agent is still relatively smooth.

[0086] Figure 4 This is a SEM image of the graphene-PBAT composite aerogel prepared in Example 2 of this application. Figure 4 It can be seen that a few pore structures also appeared on the pore walls of the graphene composite aerogel material prepared after adding the pore-forming agent.

[0087] Figure 5 This is a SEM image of the graphene-PBAT composite aerogel prepared in Example 3 of this application. Figure 5 It can be seen that the graphene composite aerogel material prepared by increasing the amount of pore-forming agent has a dense pore structure on the pore walls.

[0088] Figure 6 The image shows a physical picture (left) of the graphene-PBAT composite aerogel prepared in Example 1 of this application and a comparison picture (right) of the sample before and after compression. It can be seen from the right picture that the compressed aerogel basically rebounds completely.

[0089] It should be noted that the preparation method of the graphene oxide solution is not limited to that of the embodiments in this application, and can be prepared using other Hummers methods currently reported.

[0090] The preparation method of this application embodiment first uses the environmentally friendly amphoteric surfactant lauramidopropylamine oxide (LAO) to rapidly alkylate and modify uniformly dispersed graphene oxide (GO) prepared by the modified Hummers method: the O atoms in the abundant oxygen-containing functional groups (hydroxyl and carboxyl groups) on the surface of GO are combined with the N atoms of the amine oxide groups in LAO through electrostatic interactions in water (O... - With N + and COO - With N + Furthermore, hydrogen bonds are formed between the O atoms and LAO molecules, further stabilizing the grafting of LAO molecules onto the GO surface. The graphene modified by non-covalent grafting loses its hydrophilicity, while the long alkyl chains of the LAO molecules grafted onto the surface endow it with excellent oleophilicity, thus providing the necessary conditions for subsequent liquid-phase composite with the biodegradable material PBAT in organic solvents.

[0091] The obtained modified graphene oxide (MGO) was then combined with PBAT in a liquid phase in a 1,4-dioxane system. Under specific reaction temperatures and rotation speeds, MGO and PBAT molecules were uniformly combined in the solvent. Simultaneously, the alkyl long chains grafted onto the MGO surface intertwined with the PBAT molecules, forming physical cross-links. Meanwhile, the free nitrogen atoms on the MGO surface... + It also combines with the terminal hydroxyl and carboxyl groups in the PBAT molecular chain to form chemical cross-links. Through physical and chemical cross-linking, MGO effectively improves the problems of low strength, poor weather resistance, and low modulus of PBAT.

[0092] Finally, a composite aerogel was prepared using a simple water-assisted thermally induced phase separation (TIPS) method: a certain amount of deionized water was directly added to the system after liquid-phase composite, mixed thoroughly, and then placed in a refrigerator, with the solvent as the dispersed phase. Due to its low freezing point (12℃), 1,4-dioxane was first pre-frozen to induce phase separation, and the system gradually separated into a polymer-rich phase and a polymer-poor phase. In the polymer-rich phase, the polymer is a continuous phase that freezes, and its volume gradually increases as the temperature decreases (forming a larger porous structure after freeze-drying). When the temperature drops to 0℃, the water begins to freeze, but due to its small quantity, most of the water can only form small pores (forming a smaller porous structure after freeze-drying). Finally, the solvent and deionized water were removed by freeze-drying to obtain the graphene composite biodegradable aerogel.

[0093] Performance Test 1

[0094] The density, porosity, adsorption rate and processing performance of the biodegradable aerogel samples prepared in Examples 1-6 and Comparative Examples 1-3 were tested according to the following methods, and the results are shown in Table 1.

[0095] Density testing method: Weigh a rectangular biodegradable aerogel sample to obtain the sample mass m, and measure its length, width and thickness to obtain the sample volume V. The density ρ = m / V.

[0096] Porosity test method: Weigh the mass m0 of the biodegradable aerogel sample using an analytical balance. Immerse the biodegradable aerogel sample in a beaker containing anhydrous ethanol for 5 minutes. Weigh the total mass m1 of the beaker containing anhydrous ethanol and the biodegradable aerogel sample. Then place the beaker in a vacuum desiccator and evacuate it until no more bubbles overflow from the beaker. Remove the biodegradable aerogel sample and weigh the mass m2 of the beaker after evacuation. Porosity = (m1-m2-m0) / (m1-m2)×100%.

[0097] Adsorption rate test method: Weigh the mass m0 of the biodegradable aerogel sample, then immerse the sample in a solvent until adsorption equilibrium is reached. Remove the sample and weigh the remaining mass m1. Adsorption rate = (m1 - m0) / m0.

[0098] Processing performance test method: The biodegradable aerogel sample is cut with a cutting tool, and the processing performance of the biodegradable aerogel sample is evaluated based on whether the sample is broken or fragmented and whether the cut is neat.

[0099] Table 1

[0100]

[0101]

[0102] As shown in Table 1, the graphene-PBAT composite aerogels provided in the embodiments of this application all possess low density, high porosity, high adsorption capacity, and excellent processing performance. Compared with the pure biodegradable aerogel samples prepared in Comparative Examples 1-3, the graphene-PBAT composite aerogels prepared in Examples 1-6 have lower density, higher porosity, and higher adsorption capacity at the same amount of pore-forming agent. Furthermore, during the preparation of the same aerogel material, the optimal pore-forming effect was achieved when the amount of pore-forming agent added was 2 mL; when the amount of pore-forming agent added was 4 mL, the excessive pore structure generated by the pore-forming agent actually damaged the pore wall structure of the aerogel itself, leading to a decrease in overall performance.

[0103] Performance Test 2

[0104] Compression tests were conducted on the aerogel materials prepared in Examples 1-6 and Comparative Examples 1-3, using the method of GB / T20467-2006 as a reference. The test results are shown in Table 2.

[0105] Table 2

[0106]

[0107]

[0108] Table 2 shows that the graphene-PBAT composite aerogel exhibits the most significant improvement in compressibility when the mass ratio of modified graphene oxide to PBAT is 3 wt%. The maximum pressure at which the sample can fully rebound after compression increases from 9 N for the pure biodegradable aerogel to 14 N. This indicates that the combination of modified graphene oxide and biodegradable PBAT molecules through physical and chemical cross-linking effectively enhances the mechanical properties of the composite aerogel, providing more possibilities for its future applications in various fields. Furthermore, the test results also show that while the addition of pore-forming agents effectively increases the porosity of the aerogel, it also leads to a loss of the material's mechanical properties. In future applications, the optimal amount of pore-forming agent should be selected by comprehensively considering both the required porosity and mechanical properties of the aerogel.

[0109] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing graphene-PBAT composite aerogel, characterized in that, Includes the following steps: S1. Preparation of graphene oxide dispersion; S2. Add an amphoteric surfactant to the graphene oxide dispersion, stir until homogeneous, filter, wash, and freeze-dry to obtain modified graphene oxide. S3. Using 1,4-dioxane as a solvent, completely dissolve PBAT in 1,4-dioxane to obtain a PBAT solution. S4. The modified graphene oxide is added to the PBAT solution and ultrasonically dispersed evenly to perform liquid-phase composite. S5. After the liquid phase composite is completed, deionized water is added, stirred evenly, poured into a mold, pre-frozen, and then freeze-dried to obtain graphene-PBAT composite aerogel.

2. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, The amphoteric surfactant is one or more of lauramidopropylamine oxide, cocamidopropylamine oxide, octadecanoamide propylamine oxide, OAE-18, and OAE-14.

3. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, In step S4, the mass ratio of the modified graphene oxide to the PBAT is 1 to 3:

100.

4. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, The PBAT solution contains 6 wt% to 8 wt% by weight.

5. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, In step S4, the modified graphene oxide has a weight percentage of 0.14 wt% to 0.18 wt%.

6. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, The temperature for liquid-phase recombination is 40–50°C.

7. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, The pre-freezing treatment temperature is -10 to -20°C, and the treatment time is 12 to 24 hours.

8. The method for preparing a graphene-PBAT composite aerogel as described in claim 1, characterized in that, The freeze-drying temperature is -40 to -50°C, the vacuum degree is 1 to 10 Pa, and the time is 24 to 36 hours.

9. A method for preparing a graphene-PBAT composite aerogel according to any one of claims 1-8, characterized in that, The graphene oxide dispersion was prepared by a modified Hummers method.

10. A graphene-PBAT composite aerogel, characterized in that, It is obtained by the preparation method according to any one of claims 1-9.

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