Polyhydroxyalkanoate flexible conductive material and preparation method and application thereof

Abstract

The application discloses a kind of polyhydroxyaliphatic ester flexible conductive materials and its preparation method and application, the preparation method includes: polyhydroxyaliphatic ester is made into fiber material;Fiber material is mixed with hydrogen peroxide solution and is oxidized and handled;The fiber material obtained after oxidation processing is mixed with oxidized graphene dispersion solution, vitamin C, stirring, and polyhydroxyaliphatic ester flexible conductive material is obtained.The polyhydroxyaliphatic ester flexible conductive material prepared in the application has the advantages of high tensile strength, high conductivity and good degradability, and can be used as a raw material to prepare polyhydroxyaliphatic ester-based flexible electrodes.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology and relates to a flexible conductive material of polyhydroxyalkanoates, its preparation method and application. Background Technology

[0002] Polyhydroxyalkanoates (PHA) are a general term for high-molecular-weight polyesters produced by microbial fermentation using various carbon sources. They possess excellent biocompatibility and biodegradability, as well as physicochemical properties similar to traditional plastics, making them widely applicable in the production of biomedical materials and biodegradable plastics. However, high production and purification costs limit their further application development. Increasing the added value of PHA products is one of the mainstream development directions for balancing their high production costs. Among these, making PHA into conductive materials has high potential for value applications, especially in flexible sensors and nano-triboelectric generators, demonstrating significant research value and application prospects.

[0003] Polyhydroxyalkanoates (PHA) have over 150 monomers, most of which suffer from poor flexibility and extremely high electrical resistance. The few modified monomers with better flexibility are difficult to apply due to their high cost and unstable production. In flexible molding, large proportions of PLA or fibrous materials are commonly blended, lacking a high-proportion flexible molding pathway for PHA. There is currently a research gap in conductive modification. It is particularly important to note that while combining PHA with metal elements can improve conductivity, the doping of metals, especially heavy metal ions, should be minimized to avoid adding biotoxicity to environmentally friendly materials. Therefore, obtaining a flexible conductive material of polyhydroxyalkanoates with high tensile strength, high conductivity, and good biodegradability is of great significance for promoting the widespread application of PHA in flexible sensors, nano-triboelectric generators, and other fields. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a flexible conductive material of polyhydroxyalkanoate with high tensile strength, high electrical conductivity and good biodegradability, as well as its preparation method and application.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for preparing a flexible conductive material of polyhydroxyalkanoates includes the following steps: S1. Polyhydroxy fatty acid esters are made into fibrous materials; S2. The fiber material obtained in step S1 is mixed with hydrogen peroxide solution for oxidation treatment; S3. Mix the fiber material obtained after oxidation treatment in step S2, the graphene oxide dispersion, and vitamin C, and stir to obtain a flexible conductive material of polyhydroxyalkanoate.

[0007] In a further improvement to the above preparation method, in step S2, the mass percentage of hydrogen peroxide in the hydrogen peroxide solution is 5% to 15%.

[0008] In a further improvement to the above preparation method, in step S2, the oxidation treatment is carried out at a rotation speed of 50 rpm to 250 rpm; the oxidation treatment temperature is 25℃ to 50℃; and the oxidation treatment time is 10 min to 120 min.

[0009] The above preparation method is further improved by including the following treatment before the oxidation treatment: washing the fiber material with an ethanol solution and an acetone solution; the volume concentration of ethanol in the ethanol solution is 30% to 80%; and the volume concentration of acetone in the acetone solution is 20% to 60%.

[0010] In a further improvement to the above preparation method, in step S3, the ratio of the graphene oxide dispersion to the fiber material is 5 mL: 1 cm⁻¹. 2 ~5 mL∶4 cm 2 The mass ratio of graphene oxide to vitamin C is 0.1 to 1:1; the concentration of the graphene oxide dispersion is 0.5 mg / mL to 10 mg / mL. It should be noted that when the concentration is too high, aggregation can easily occur, leading to unevenness and instability; when the concentration is too low, the conductivity can easily be too low.

[0011] In a further improvement to the above preparation method, in step S3, the graphene oxide dispersion and vitamin C are first mixed and then added to the fiber material obtained after oxidation treatment in step S2; the stirring is carried out at a speed of 100 rpm to 600 rpm and a temperature of 40℃ to 85℃; the stirring time is 3h to 6h; after the stirring is completed, the following treatment is also included: the stirred product is dried at 60℃ for 20min to 60min, washed with ultrapure water, and the washed product is dried at 60℃ for 20min to 60min to obtain a polyhydroxyalkanoate flexible conductive material.

[0012] A further improvement to the above preparation method is that, in step S1, the polyhydroxyalkanoate is made into a fiber material using electrospinning, including the following steps: S11. Mix polyhydroxyalkanoate with an organic solvent, and sonicate or stir to obtain a polyhydroxyalkanoate solution. S12. Electrospinning is performed using a polyhydroxyalkanoate solution as the spinning solution to obtain fiber material.

[0013] In a further improvement to the above preparation method, in step S11, the polyhydroxy fatty acid ester solution contains 3% to 8% by mass of the polyhydroxy fatty acid ester; the polyhydroxy fatty acid ester includes at least one of PHB, PHBV, and P34HB; the polyhydroxy fatty acid ester is in powder form and sieved through a mesh size of not less than 40 mesh, including 40 mesh; the organic solvent is a mixture of a first component and a second component; the first component includes at least one of chloroform, N,N-dimethylformamide, and dichloromethane; the second component is ethanol; and the organic solvent contains 5% to 25% by mass of the second component.

[0014] In a further improvement to the above preparation method, in step S12, the electrospinning process parameters are as follows: positive electrode voltage is 16 kV to 25 kV, negative electrode voltage is 0 to -5 kV, roller speed is 100 rpm to 300 rpm, spinning distance is 140 mm, needle distance is 8 cm to 12 cm, and solution flow rate is 0.05 mL / h to 15 mL / h; during the electrospinning process, the humidity of the system is controlled at 50% to 80%, and the temperature is 25℃.

[0015] As a general technical concept, the present invention also provides a flexible conductive material of polyhydroxyalkanoate, which is prepared by the above-described preparation method.

[0016] The above-mentioned flexible conductive material of polyhydroxyalkanoates is further improved by comprising polyhydroxyalkanoate fibers, wherein the surface of the polyhydroxyalkanoate fibers is loaded with reduced graphene oxide.

[0017] As a general technical concept, the present invention also provides the application of the above-mentioned polyhydroxyalkanoate flexible conductive material as a raw material in the preparation of flexible electrodes.

[0018] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention creatively provides a method for preparing a flexible conductive material of polyhydroxyalkanoate. The fiber material is made from polyhydroxyalkanoate as raw material, which is beneficial to improve the degradability and tensile strength of the material. Then, hydrogen peroxide is used to oxidize the fiber material to enhance the oxygen-containing functional groups on the surface of the fiber material, which can promote the adsorption capacity of the fiber material for graphene oxide, so that more graphene oxide is adsorbed on the surface of the fiber material, which is beneficial to improve the loading of conductive material (reduced graphene oxide) on the surface of the fiber material. Finally, the fiber material, graphene oxide dispersion and vitamin C are mixed, and the graphene oxide can be reduced to reduced graphene oxide and loaded on the surface of the fiber material by simple stirring. Thus, under the combined action of the fiber material and reduced graphene oxide, the conductivity of the material can be significantly improved. Finally, a flexible conductive material of polyhydroxyalkanoate with high tensile strength, high conductivity and good degradability is prepared. This flexible conductive material of polyhydroxyalkanoate can be used as a raw material to prepare PHA-based flexible electrodes, which can be widely used in flexible sensors, nano-triboelectric generators and other fields.

[0019] (2) In this invention, polyhydroxy fatty acid esters are made into fiber materials by electrospinning. By optimizing the type and amount of polyhydroxy fatty acid esters in the spinning solution, the composition of the organic solvent and the amount of each component, fiber materials with higher tensile strength can be obtained. Attached Figure Description

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0021] Figure 1 This is a graph showing the change in the O / C ratio in the fiber material prepared in Example 1 of the present invention with the time of hydrogen peroxide oxidation.

[0022] Figure 2 The images shown are SEM images of the fiber materials prepared in Example 1 and Comparative Example 1 of this invention.

[0023] Figure 3 The figures show the stress-strain test results of the fiber materials prepared in Examples 1 and 2 of this invention.

[0024] Figure 4 The images show SEM images of the fiber material and polyhydroxyalkanoate flexible conductive material prepared in Example 1 of this invention.

[0025] Figure 5 The graph shows the mass changes of the polyhydroxyalkanoate flexible conductive material, polyhydroxyalkanoate fiber material, and polyhydroxyalkanoate powder prepared in Example 1 of this invention under pure water and ultrasonic conditions.

[0026] Figure 6 The graph shows the degradation effect of the polyhydroxyalkanoate flexible conductive material prepared in Example 1 of this invention under different conditions. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0028] In the following embodiments of the present invention, unless otherwise specified, the materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0029] Example 1: A method for preparing a flexible conductive material of polyhydroxyalkanoates includes the following steps: S1. Polyhydroxyalkanoates are made into fiber materials using electrospinning, specifically: S11. Take polyhydroxy fatty acid ester powder that has passed through a 40-mesh sieve, mix the polyhydroxy fatty acid ester powder with an organic solvent (a mixture of chloroform and ethanol), and dissolve the polyhydroxy fatty acid ester powder in chloroform to obtain a polyhydroxy fatty acid ester solution with a mass percentage of 5%.

[0030] In step S11, the polyhydroxy fatty acid ester powder used is polyhydroxybutyrate (PHB). In other embodiments, the polyhydroxy fatty acid ester powder may also be polyhydroxybutyrate-valerate copolyester (PHBV) or poly(3-hydroxybutyrate-4-hydroxybutyrate copolyester) (P34HB), but the polyhydroxy fatty acid ester powder used in this invention is not limited to PHB, PHBV, or P34HB.

[0031] In step S11, the organic solvent used contains 10% ethanol by mass, meaning the first component (chloroform) contains 90% chloroform by mass. In addition to chloroform, in other embodiments, the first component may also be N,N-dimethylformamide or dichloromethane; however, the first component used in this invention is not limited to chloroform, N,N-dimethylformamide, or dichloromethane.

[0032] In step S11, in other embodiments, the mass percentage of polyhydroxyalkanoate in the prepared polyhydroxyalkanoate solution can also be 3%, 4%, 6%, 7%, or 8%. In this invention, optimizing the mass percentage of polyhydroxyalkanoate in the polyhydroxyalkanoate solution is beneficial for the more stable preparation of spinning materials. When the content is too low, the spinning film will not form properly, while when the content is too high, it is easy to cause clogging, which is not conducive to operation.

[0033] S12. Electrospinning was performed using a polyhydroxyalkanoate solution as the spinning solution, wherein the positive electrode voltage was 20kV, the negative electrode voltage was -3kV, the roller speed was 200 rpm, the spinning distance was 140 mm, the needle distance was 10 cm, the humidity was 80%, the temperature was 25℃, and the solution flow rate was 15mL / h to obtain fiber material.

[0034] S2. The fiber material obtained in step S1 is mixed with hydrogen peroxide solution for oxidation treatment, specifically as follows: S21. The fiber material obtained in step S1 is washed with a mixed solution of ethanol and acetone to remove impurities from the surface of the fiber material.

[0035] In step 21, the ethanol solution (obtained by mixing ethanol and water) has a volume concentration of 40% ethanol, and the acetone solution (obtained by mixing acetone and water) has a volume concentration of 40% acetone.

[0036] S22. The washed fiber material from step S21 is mixed with a 10% hydrogen peroxide solution and oxidized for 30 minutes at 100 rpm and 40°C to increase the type and number of oxygen-containing functional groups on the surface of the fiber material.

[0037] In step 22, the mass percentage of hydrogen peroxide in the hydrogen peroxide solution can also be 5%, 6%, 7%, 8%, 9%, 11%, 12%, 13%, 14%, or 15%, but is not limited to these.

[0038] S3. Mix the fiber material obtained after oxidation treatment in step S2, the graphene oxide dispersion, and vitamin C, and stir to obtain a flexible conductive material of polyhydroxyalkanoate, specifically: S31. The ratio of graphene oxide dispersion to fiber material is 5 mL: 2 cm⁻¹. 2 The mass ratio of graphene oxide to vitamin C is 0.2:1. 20 mL of graphene oxide dispersion with a concentration of 5 mg / mL is mixed with 500 mg of vitamin C and added to the fiber material obtained after oxidation treatment in step S2. The mixture is stirred for 4 h at a speed of 400 rpm and a temperature of 85 °C to obtain a fiber material dispersion loaded with reduced graphene oxide.

[0039] In step S31, in other embodiments, the graphene oxide dispersion can be configured in any proportion according to material requirements, such as 1.25 mg / mL, 6.5 mg / mL, etc., but is not limited to this.

[0040] In step S31, in other embodiments, the mass ratio of graphene oxide to vitamin C can also be 0.1∶1, 0.3∶1, 0.4∶1, 0.5∶1, 0.6∶1, 0.7∶1, 0.8∶1, 0.9∶1, 1∶1, but is not limited to these.

[0041] In step S31, in other embodiments, the ratio of graphene oxide dispersion to fiber material can also be 5 mL: 1 cm⁻¹. 2 5 mL ∶ 3 cm 2 5 mL ∶ 4 cm 2 .

[0042] S32. Pour the fiber material dispersion loaded with reduced graphene oxide into a glass petri dish and dry it at 60°C for 20 minutes to obtain the fiber material loaded with reduced graphene oxide.

[0043] S33. The fiber material loaded with reduced graphene oxide is rinsed with ultrapure water to remove surface impurities and excess particulate matter, and then dried at 60°C for 45 minutes to obtain a flexible conductive material of polyhydroxyalkanoate.

[0044] In this embodiment, the prepared polyhydroxyalkanoate flexible conductive material includes polyhydroxyalkanoate fibers, on which reduced graphene oxide (rGO) is loaded.

[0045] In this invention, polyhydroxyalkanoate fibers are used as a carrier, enabling the flexible conductive material to possess excellent biocompatibility, flexibility, and toughness. Based on this, reduced graphene oxide is loaded onto the surface of the polyhydroxyalkanoate fibers. Since reduced graphene oxide is an excellent green conductive material, using it as a conductive sensitive layer is beneficial for preparing a bio-friendly flexible sensing electrode, providing a possibility for the rapidly developing fields of flexible human body sensors, nano-triboelectric generators, and so on.

[0046] In this embodiment, the prepared polyhydroxyalkanoate flexible conductive material can be used as a raw material in the preparation of flexible electrodes.

[0047] Comparative Example 1: A method for preparing a fiber material is basically the same as that in Example 1, except that in step S1 of Comparative Example 1, the organic solvent used is chloroform, that is, the mass percentage of the first component in the organic solvent is 100%.

[0048] Example 2: A method for preparing a flexible conductive material of polyhydroxyalkanoate is basically the same as that in Example 1, except that in step S1 of Example 2, the organic solvent used is a mixture of a first component and a second component, wherein the first component is chloroform, the second component is ethanol, and the mass percentage of the first component in the organic solvent is 80%.

[0049] Example 3: A method for preparing a flexible conductive material of polyhydroxyalkanoate is basically the same as that in Example 1, except that in step S1 of Example 3, the humidity is controlled at 50% during the electrospinning process.

[0050] Figure 1 This is a graph showing the change in the O / C ratio in the fiber material prepared in Example 1 of the present invention with the time of hydrogen peroxide oxidation. Figure 1 It can be seen that as the oxidation time increases from 0 to 30 min, the O / C ratio of the material under XPS increases (from 0.428 to 0.459), indicating that the number of oxygen-containing functional groups increases with the increase of oxidation time. At this time, the chemical reactivity of the fiber material is enhanced, which is more conducive to chemical bonding with graphene oxide or partially reduced graphene oxide, thereby increasing the overall structural strength.

[0051] Figure 2 The images shown are SEM images of the fiber materials prepared in Example 1 and Comparative Example 1 of this invention. Figure 2 In the text, a represents Example 1, and b represents Comparative Example 1. From... Figure 2 It can be seen that, compared with chlorophenol alone, in Example 1, the fiber material prepared by using a mixed solvent of chloroform and ethanol as the organic solvent has a more uniform and slender diameter, a smoother surface, and less adhesion between different fibers, which helps to form a more resilient network structure.

[0052] Figure 3 The figures show the stress-strain test results of the fiber materials prepared in Examples 1 and 2 of this invention. Figure 3 It can be seen that in Example 1, when the content of the second component (ethanol) is 10%, relatively good mechanical properties (tensile strength and elongation at break) can be obtained. In Example 2, when the content of the second component (ethanol) increases to 20%, the mechanical properties decrease.

[0053] Figure 4 The images show SEM images of the fiber material and polyhydroxyalkanoate flexible conductive material prepared in Example 1 of this invention. Figure 4 In the diagram, 'a' represents a fiber material, and 'b' represents a flexible conductive polyhydroxyalkanoate material. Figure 4It can be seen that when rGO is not loaded, the fiber is smooth, thin and straight. When a certain amount of rGO is loaded, a continuous conductive network of typical sheet-like graphene structure can be observed on the fiber surface and in the gaps, which can make the material conductive.

[0054] Figure 5 This is a graph showing the mass changes of the polyhydroxyalkanoate flexible conductive material, polyhydroxyalkanoate fiber material, and polyhydroxyalkanoate powder prepared in Example 1 of this invention under pure water and ultrasonic conditions. Figure 5 It can be seen that the degradation rate of PHA fiber material is greater than that of material loaded with rGO, and much greater than that of pure PHA particles. Under the same conditions, the ultrasonic degradation effect is related to the sites of its cavitation effect, indicating that the polyhydroxyalkanoate fiber material prepared by electrospinning has more contact sites than the particulate form. At the same time, after graphene is combined with polyhydroxyalkanoate fiber material, the degradation performance is slightly reduced because graphene occupies a certain site space.

[0055] Figure 6 The graph shows the degradation effect of the polyhydroxyalkanoate flexible conductive material prepared in Example 1 of this invention under different conditions. Figure 6 In the diagram, 'a' represents oscillation in pure water for 96 hours, and 'b' represents oscillation in the Xiangjiang River for 96 hours. Figure 6 It can be seen that PHA in pure water did not change its form after being placed, while PHA in natural water bodies showed a significant decrease in mass, an increase in hydrophilicity, and was loaded with brown active sediment after being placed. This indicates that PHA adsorbed many microorganisms in the water body for utilization and oxidation of the material. This shows that PHA is a non-toxic organic carbon source that can be rapidly utilized by microorganisms and can be degraded harmlessly after use and disposal.

[0056] In addition, the performance data of the polyhydroxy fatty acid ester flexible conductive materials prepared in Examples 1-3 of the present invention are shown in Table 1.

[0057] Table 1 Performance data of the polyhydroxyalkanoate flexible conductive materials prepared in Examples 1-3 of this invention

[0058] As can be seen from the above results, the polyhydroxyalkanoate flexible conductive material prepared by the present invention has the advantages of high tensile strength, high conductivity and good degradability. It can be used as a raw material to prepare PHA-based flexible electrodes and can be widely used in flexible sensors, nano-triboelectric generators and other fields.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing a flexible conductive material of polyhydroxyalkanoates, characterized in that, Includes the following steps: S1. Polyhydroxy fatty acid esters are made into fibrous materials; S2. The fiber material obtained in step S1 is mixed with hydrogen peroxide solution for oxidation treatment; S3. Mix the fiber material obtained after oxidation treatment in step S2, the graphene oxide dispersion, and vitamin C, and stir to obtain a flexible conductive material of polyhydroxyalkanoate.

2. The preparation method according to claim 1, characterized in that, In step S2, the mass percentage of hydrogen peroxide in the hydrogen peroxide solution is 5% to 15%.

3. The preparation method according to claim 2, characterized in that, In step S2, the oxidation treatment is carried out at a rotation speed of 50 rpm to 200 rpm; the oxidation treatment temperature is 25°C to 50°C; the oxidation treatment time is 10 min to 120 min; before the oxidation treatment, the following treatment is also included: washing the fiber material with an ethanol solution and an acetone solution; the volume concentration of ethanol in the ethanol solution is 30% to 80%; the volume concentration of acetone in the acetone solution is 20% to 60%.

4. The preparation method according to claim 3, characterized in that, In step S3, the ratio of the graphene oxide dispersion to the fiber material is 5 mL: 1 cm⁻¹. 2 ~5 mL∶4 cm 2 The mass ratio of graphene oxide to vitamin C is 0.1 to 1:1; the concentration of the graphene oxide dispersion is 0.5 mg / mL to 10 mg / mL.

5. The preparation method according to claim 4, characterized in that, In step S3, the graphene oxide dispersion and vitamin C are mixed and added to the fiber material obtained after oxidation treatment in step S2. The stirring is carried out at a speed of 100 rpm to 600 rpm and a temperature of 40℃ to 85℃. The stirring time is 3h to 6h. After the stirring is completed, the following treatment is also included: the stirred product is dried at 60℃ for 20min to 60min, washed with ultrapure water, and the washed product is dried at 60℃ for 20min to 60min to obtain a polyhydroxyalkanoate flexible conductive material.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step S1, polyhydroxyalkanoates are made into fibrous materials using electrospinning, including the following steps: S11. Mix polyhydroxyalkanoate with an organic solvent, and sonicate or stir to obtain a polyhydroxyalkanoate solution. S12. Electrospinning is performed using a polyhydroxyalkanoate solution as the spinning solution to obtain fiber material.

7. The preparation method according to claim 6, characterized in that, In step S11, the polyhydroxyalkanoate solution contains 3% to 8% polyhydroxyalkanoate by mass; the polyhydroxyalkanoate includes at least one of PHB, PHBV, and P34HB; the polyhydroxyalkanoate is in powder form and sieved through a mesh size of not less than 40; the organic solvent is a mixture of a first component and a second component; the first component includes at least one of chloroform, N,N-dimethylformamide, and dichloromethane; the second component is ethanol; the organic solvent contains 5% to 25% by mass of the second component. In step S12, the electrospinning process parameters are as follows: positive electrode voltage is 16 kV to 25 kV, negative electrode voltage is 0 to -5 kV, roller speed is 100 rpm to 300 rpm, spinning distance is 140 mm, needle distance is 8 cm to 12 cm, and solution flow rate is 0.05 mL / h to 10 mL / h; during the electrospinning process, the humidity of the system is controlled at 50% to 80%, and the temperature is 25℃.

8. A flexible conductive material made of polyhydroxyalkanoate, characterized in that, The polyhydroxyalkanoate flexible conductive material is prepared by any one of claims 1 to 7.

9. The polyhydroxyalkanoate flexible conductive material according to claim 8, characterized in that, The polyhydroxyalkanoate flexible conductive material includes polyhydroxyalkanoate fibers, the surface of which is loaded with reduced graphene oxide.

10. The use of the polyhydroxyalkanoate flexible conductive material as described in claim 8 or 9 as a raw material in the preparation of flexible electrodes.

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