Triboelectric film based on C-lignin and preparation method and application thereof

Abstract

The invention belongs to the technical field of biomass-based friction materials, and discloses a triboelectric film based on C-lignin and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing polyvinyl alcohol with a solvent, heating and stirring, adding carbon nanotubes, and mixing to obtain a polyvinyl alcohol mixture; and (2) mixing C-lignin with ethanol to obtain a C-lignin mixture, then adding the C-lignin mixture into the polyvinyl alcohol mixture prepared in the step (1), carrying out heating reaction, pouring into a mold, and drying to obtain the triboelectric film. The specific raw materials selected by the preparation method are matched with the triboelectric film prepared in the preparation process, and the overall mechanical performance of the triboelectric film is remarkably improved through the synergistic effect of the nanometer constraint effect and the solvent induction effect. For example, the tensile strength can reach 43.1 MPa, and the fracture toughness can reach 512.3 MJ / m < 3 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass-based triboelectric materials, and in particular relates to a triboelectric film based on C-lignin, and a preparation method and application thereof. Background Art

[0002] With the rapid development of the intelligent society and the growing awareness of environmental sustainability, the development of green, environmentally friendly, and efficient self-powered biomass-based wearable smart electronic devices has become a research hotspot. These devices have broad application prospects in fields such as human-computer interaction, health monitoring, and aerospace.

[0003] Lignin, an abundant aromatic biomass resource in nature, holds broad application prospects. Lignin's rich aromatic rings, hydroxyl groups, and quinone structures, in particular, can exhibit excellent electrical properties by optimizing its electron transport capacity through chemical or physical means. However, due to its complex structure and heterogeneity, traditional lignin faces numerous challenges when combined with other materials, limiting its performance in wearable smart electronic devices.

[0004] To date, traditional biomass-based wearable smart electronic devices have relied primarily on external power sources, often requiring bulky power supplies, severely hindering their rapid development. Triboelectric nanogenerators (TENGs), based on frictional charging and electrostatic induction coupling, convert environmental mechanical energy into electrical signals, thereby enabling the independence and portability of biomass-based wearable smart electronics. Currently, the research and application of self-powered biomass wearable smart electronics hinges on whether the material's superior mechanical properties are highly compatible with the motion of soft living tissues, significantly impacting their mechanical durability and adaptability to real-world environments. Therefore, the development of self-powered biomass wearable smart electronic devices with comprehensive mechanical performance advantages that meet diverse application scenarios is crucial for achieving ideal applications. Unfortunately, high robustness and supertoughness are mutually exclusive structural properties. Generally speaking, highly robust materials exhibit increased hardness and are prone to brittle fracture upon impact, raising concerns about their sustainability and reliability. However, high strength and supertoughness are often mutually exclusive. High-strength materials exhibit increased hardness and are prone to brittle fracture upon impact, raising serious concerns about their sustainability and reliability. How to effectively address the compatibility issue between strength and toughness in biomass-based self-powered wearable smart electronic devices is a current research focus. In particular, the design and application of self-powered wearable smart electronic devices with high mechanical properties have not yet been reported. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a triboelectric film based on C-lignin and its preparation method and application.

[0006] The triboelectric film described in this invention addresses the difficulty of achieving both strength and toughness in existing biomass-based triboelectric films. The preparation process of the triboelectric film described in this invention utilizes the synergistic effects of nanoconfinement and solvent-induced effects. On the one hand, the nanoconfinement effect fully utilizes the uniform shear deformation of hydrogen bonds and the molecular viscous dissipative deformation mechanism, thereby significantly improving the overall mechanical properties of the C-lignin-based triboelectric film. On the other hand, the solvent-induced effect forms a stable microphase separation structure, optimizing the overall uniformity of the system, thereby enhancing the controllability of the nanocluster phase and making the polymer network more inclined to form a regular molecular chain arrangement. Ultimately, high strength and super-toughness are achieved.

[0007] A first aspect of the present invention provides a method for preparing a triboelectric film based on C-lignin.

[0008] A method for preparing a triboelectric film based on C-lignin comprises the following steps: (1) polyvinyl alcohol (PVA) and a solvent are mixed, heated and stirred, carbon nanotubes (CNTs) are added, and mixed to obtain a polyvinyl alcohol mixture; (2) C-lignin (CL) is mixed with ethanol to obtain a C-lignin mixture, and then the C-lignin mixture is added to the polyvinyl alcohol mixture prepared in step (1), heated for reaction, poured into a mold, and dried to obtain the triboelectric film.

[0009] Preferably, in step (1), the solvent is water, such as deionized water.

[0010] Preferably, in step (1), the ratio of the amount of polyvinyl alcohol to the solvent is 6 g: (20-60) mL, more preferably 6 g: 30-40 mL.

[0011] Preferably, in step (1), the heating and stirring is performed at a temperature of 70-90°C for 1-2 hours. Stirring at this temperature is conducive to the full dissolution of the polyvinyl alcohol.

[0012] Preferably, in step (1), the mass ratio of the polyvinyl alcohol to the carbon nanotubes is 6:(0.03-0.1), more preferably 6:(0.05-0.08).

[0013] Preferably, in step (2), the mass concentration of the C-lignin mixture is 5-30%, more preferably 10-20%.

[0014] Preferably, in step (2), the volume of the C-lignin mixture is 1-20 mL, more preferably 2-10 mL. Preferably, in step (2), the heating reaction temperature is 90-95° C. and the time is 3-4 hours.

[0015] Preferably, in step (2), the C-lignin mixture is added to the polyvinyl alcohol mixture prepared in step (1) in multiple additions. The multiple additions refer to two or more times, for example, 2-10 times. Multiple additions ensure the formation of the nanocluster phase and its uniform dispersion in the solution, which has a promoting effect on improving the mechanical properties of the C-lignin-based triboelectric film.

[0016] Preferably, in step (2), the drying temperature is 40-60° C. and the drying time is 4-6 hours.

[0017] A second aspect of the present invention provides a triboelectric film.

[0018] A triboelectric film is prepared by the above preparation method.

[0019] Preferably, the thickness of the triboelectric film is 50-300 μm, more preferably 100-200 μm.

[0020] Preferably, the tensile strength of the triboelectric film exceeds 40 MPa, for example, exceeds 43 MPa.

[0021] Preferably, the fracture toughness of the triboelectric film exceeds 500 MJ / m 3 , for example, more than 510MJ / m 3 .

[0022] A third aspect of the present invention provides an application of a triboelectric film.

[0023] A self-powered intelligent electronic device comprises the above-mentioned triboelectric film.

[0024] Preferably, the intelligent electronic device is a flexible self-powered intelligent electronic device.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The triboelectric film prepared by the specific raw materials selected by the preparation method of the present invention and the preparation process significantly improves the overall mechanical properties of the triboelectric film through the synergistic effect of nano-confinement effect and solvent-induced effect. For example, the tensile strength can reach 43.1MPa and the fracture toughness can reach 512.3MJ / m 3 .

[0026] (2) The triboelectric film of the present invention also has excellent energy dissipation efficiency, for example, the energy dissipation efficiency reaches 94.9%, which is significantly better than pure PVA film and other reported biomass-based triboelectric films.

[0027] (3) The triboelectric film of the present invention also has good antibacterial properties. For example, it has a significant antibacterial effect on Escherichia coli and Staphylococcus aureus and can effectively reduce the survival rate of bacteria.

[0028] (4) The triboelectric film of the present invention also has excellent antioxidant ability. For example, it exhibits excellent antioxidant performance in the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) free radical scavenging activity test, with a maximum inhibition rate of up to 53.4%.

[0029] (5) The triboelectric film of the present invention also has excellent self-powered sensing performance: the self-powered wearable sensor constructed based on the triboelectric film exhibits fast response (49mS), high open circuit voltage (245.1V) and long service life (stable performance after 7500 cycles), and can monitor the human body's movement status in real time.

[0030] (6) The triboelectric film of the present invention has good recyclability. After multiple recycling cycles, its mechanical properties can still be maintained at more than 95.2% of the initial value, providing technical support for the development of green and sustainable self-powered smart electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 These are the stress-strain curve results of the triboelectric films prepared in Examples 1-5 and Comparative Example 1. DETAILED DESCRIPTION

[0032] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0033] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0034] In the following examples, the raw materials PVA refers to polyvinyl alcohol, CNT refers to carbon nanotubes, and CL refers to C-lignin.

[0035] Example 1 A method for preparing a triboelectric film based on C-lignin comprises the following steps: Dissolve 6 g of PVA powder in 40 mL of deionized water and heat with stirring at 90 °C for 2 h until completely dissolved; Then, 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; 0.1 g of CL was dissolved in 2 mL of ethanol solution to obtain a CL mixture, which was then added to the above-mentioned PVA mixture in five portions and heated at 95 °C for 4 h. After the reaction was completed, the obtained mixture was evenly poured into a mold and dried at 60 °C for 6 h to obtain a C-lignin-based triboelectric film (named CCLPF-5) with a thickness of approximately 150 μm.

[0036] Example 2 A method for preparing a triboelectric film based on C-lignin comprises the following steps: Dissolve 6 g of PVA powder in 40 mL of deionized water and heat with stirring at 90 °C for 2 h until completely dissolved; Then, 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; 0.2 g of CL was dissolved in 2 mL of ethanol solution to obtain a CL mixture, which was then added to the above-mentioned PVA mixture in five portions and heated at 95 °C for 4 h. After the reaction was completed, the obtained mixture was evenly poured into a mold and dried at 60 °C for 6 h to obtain a C-lignin-based triboelectric film (named CCLPF-10) with a thickness of approximately 150 μm.

[0037] Example 3 A method for preparing a triboelectric film based on C-lignin comprises the following steps: Dissolve 6 g of PVA powder in 40 mL of deionized water and heat with stirring at 90 °C for 2 h until completely dissolved; Then, 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; 0.3 g of CL was dissolved in 2 mL of ethanol solution to obtain a CL mixture, which was then added to the above-mentioned PVA mixture in five portions and heated at 95 °C for 4 h. After the reaction was completed, the obtained mixture was evenly poured into a mold and dried at 60 °C for 6 h to obtain a C-lignin-based triboelectric film (named CCLPF-15) with a thickness of approximately 150 μm.

[0038] Example 4 A method for preparing a triboelectric film based on C-lignin comprises the following steps: Dissolve 6 g of PVA powder in 40 mL of deionized water and heat with stirring at 90 °C for 2 h until completely dissolved; Then, 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; 0.4 g of CL was dissolved in 2 mL of ethanol solution to obtain a CL mixture, which was then added to the above-mentioned PVA mixture in five portions and heated at 95 °C for 4 h. After the reaction was completed, the obtained mixture was evenly poured into a mold and dried at 60 °C for 6 h to obtain a C-lignin-based triboelectric film (named CCLPF-20) with a thickness of approximately 150 μm.

[0039] Example 5 A method for preparing a triboelectric film based on C-lignin comprises the following steps: Dissolve 6 g of PVA powder in 40 mL of deionized water and heat with stirring at 90 °C for 2 h until completely dissolved; Then, 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; 0.5 g of CL was dissolved in 2 mL of ethanol solution to obtain a CL mixture, which was then added to the above-mentioned PVA mixture in five portions and heated at 95 °C for 4 h. After the reaction was completed, the obtained mixture was evenly poured into a mold and dried at 60 °C for 6 h to obtain a C-lignin-based triboelectric film (named CCLPF-25) with a thickness of approximately 150 μm.

[0040] Comparative Example 1 A method for preparing a triboelectric film comprises the following steps: Dissolve 6 g of PVA powder in 40 mL of deionized water and heat with stirring at 90 °C for 2 h until completely dissolved; Then 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture. The mixture was evenly poured into a mold and dried at 60 °C for 6 h to obtain a C-lignin-based triboelectric film (named PPF) with a thickness of approximately 150 μm.

[0041] Comparative Example 2 A triboelectric film based on a ternary composite of tannic acid (TA) / cellulose nanocrystals (CNC) / polyvinyl alcohol is prepared as follows: 8 g of PVA powder was dissolved in 92 mL of deionized water, heated to 90 °C and stirred for 2 h until completely dissolved to obtain a PVA solution; 15% CNC and 15% TA were added to the above PVA solution and stirred at 90°C for 4 hours. Then 20 mL of ethanol was added and stirred for 4 hours. The resulting mixture was evenly poured into a mold and dried at 60°C for 6 hours to obtain a triboelectric film with a thickness of about 150 μm.

[0042] Comparative Example 3 A cellulose nanofiber (CNF) / polyvinyl alcohol binary composite triboelectric film, the preparation method of which is as follows: Dissolve 10 g of PVA powder in 90 mL of deionized water, heat to 90 °C and continue stirring for 4 hours until it is completely dissolved to obtain a PVA solution; 100 mL of CNF suspension (2.0 wt%) was added to the above-mentioned PVA solution and stirred at 60°C for 3 hours to obtain a PVA / CNF mixed solution. 15 mL of the PVA / CNF mixed solution was poured into a glass plate mold and quickly frozen in a -20°C refrigerator. The frozen sample was immersed in 80% ethanol solution for 6 hours. Finally, the sample was dried at 45°C to obtain a triboelectric film with a thickness of approximately 150 μm.

[0043] Comparative Example 4 A binary composite triboelectric film based on enzymatically hydrolyzed lignin (EHL) / polyvinyl alcohol (PVA) is prepared as follows: 10 g of PVA powder was dissolved in 90 mL of deionized water, heated to 90 °C and stirred for 2 h until completely dissolved, and then 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; A 3wt% enzymatically hydrolyzed lignin (EHL) suspension was mixed with a PVA mixture in a volume ratio of 1:9 and heated on a magnetic stirrer for 15 minutes. After the reaction was completed, the obtained mixture was poured onto a Petri dish and air-dried in a laboratory fume hood to obtain a triboelectric film with a thickness of approximately 150μm.

[0044] Comparative Example 5 A demethylated lignin (DL) / polyvinyl alcohol (PVA) binary composite triboelectric film, the preparation method of which is as follows: 10 g of PVA powder was dissolved in 90 mL of deionized water, heated to 95 °C and stirred continuously for 4 h until completely dissolved, and then 0.05 g of CNT was added and mixed thoroughly to ensure uniform dispersion to obtain a PVA mixture; A 4wt% demethylated lignin (DL) suspension and a 2% calcium chloride solution were mixed with the PVA mixture in a volume ratio of 1:1:18 and heated on a magnetic stirrer for 60 minutes. After the reaction was completed, the obtained mixture was poured onto a Petri dish and air-dried in a laboratory fume hood to obtain a triboelectric film with a thickness of approximately 150μm.

[0045] Application Examples Self-powered flexible wearable sensors based on CCLPF-20 (the triboelectric film prepared in Example 4) demonstrate significant potential for human motion monitoring. Their ability to monitor human motion in real time lends them to applications in health diagnosis, sports rehabilitation, and human-computer interaction. For example, by monitoring the bending and recovery of the elbow, the self-powered flexible wearable sensor can accurately detect and identify the elbow's motion state and provide real-time feedback on the elbow's velocity through the relative frequency of the signal. Furthermore, the self-powered flexible wearable sensor demonstrates excellent knee joint monitoring, effectively monitoring the degree of knee flexion and thus accurately determining gait. Importantly, the CCLPF-20-based self-powered flexible wearable sensor can clearly distinguish between typical motion states, including complex movements such as walking, running, and jumping. It can also identify abnormal gaits. For example, when a person falls, the output signal peak value of the self-powered flexible wearable sensor significantly decreases and exhibits a spike characteristic. Furthermore, by providing real-time feedback of the triboelectric output signal, the self-powered flexible wearable sensor can clearly distinguish between upward and downward motion states. These results show that the self-powered flexible wearable sensor assembled based on CCLPF-20 has excellent mechanical stability and sensitivity, and is a flexible electronic device with great development prospects. It is not only suitable for training and monitoring of various body postures, but also provides an important reference for the development of the next generation of sustainable self-powered wearable electronic devices, showing broad application prospects.

[0046] Product effect testing 1. Triboelectric film performance test The triboelectric films prepared in Examples 1-5 and Comparative Example 1 were tested for their stress-strain curves. Figure 1 As shown. Figure 1 ( Figure 1 (“Strain” represents elongation at break, and “Stress” represents tensile strength) It can be seen that the triboelectric films prepared in Examples 1-5 have good tensile strength and fracture toughness compared with Comparative Example 1.

[0047] The triboelectric films prepared in Examples 1-5 and Comparative Examples 1-5 were tested for tensile strength, elongation at break, fracture toughness, and energy dissipation efficiency according to the standard (GB / T 24218.3-2010). The antibacterial rate against Escherichia coli and Staphylococcus aureus was tested using the shake flask method, and the cell viability was analyzed using the MTT method to evaluate biocompatibility. The DPPH free radical scavenging rate was tested according to the standard (GB / T45178-2024). The results are shown in Table 1.

[0048] Table 1: Triboelectric film performance test results

[0049] As can be seen from Table 1, the triboelectric films prepared in Examples of the present invention exhibit improved tensile strength, elongation at break, fracture toughness, energy dissipation efficiency, antibacterial efficiency, and DPPH radical scavenging efficiency. This demonstrates that the specific raw materials and preparation process of the present invention significantly enhance the performance of triboelectric films.

[0050] 2. Performance test of self-powered flexible wearable sensor The open circuit voltage of the self-powered wearable sensor built based on CCLPF-20 is 245.1V, the response time is 49mS, and the open circuit voltage remains at 94% of the initial value after 7500 cycles. 94%=230.4V.

[0051] Based on the triboelectric films prepared in Comparative Examples 2 and 3, the performance of the wearable sensor prepared in the same manner is as follows: the open circuit voltage of the wearable sensor corresponding to Comparative Example 2 is 208 V, the response time is 58 mS, and the performance remains at 91% of the initial value after 7500 cycles, that is, the open circuit voltage after 7500 cycles is 208 V. 91%=189.28V; the open circuit voltage of the wearable sensor corresponding to Example 3 is 168V, the response time is 61mS, and the performance remains at 89% of the initial value after 7500 cycles, that is, the open circuit voltage after 7500 cycles is 168 89%=149.5V.

Claims

1. A method for preparing a triboelectric film based on C-lignin, characterized in that: The following steps are involved: (1) mixing polyvinyl alcohol with a solvent, heating and stirring, then adding carbon nanotubes and mixing to obtain a polyvinyl alcohol mixture; (2) C-lignin is mixed with ethanol to obtain a C-lignin mixture, and then the C-lignin mixture is added to the polyvinyl alcohol mixture prepared in step (1), heated for reaction, poured into a mold, and dried to obtain the triboelectric film.

2. The preparation method according to claim 1, characterized in that In step (1), the ratio of the amount of polyvinyl alcohol to the solvent is 6 g: (20-60) mL.

3. The preparation method according to claim 1, characterized in that In step (1), the mass ratio of the polyvinyl alcohol to the carbon nanotubes is 6:(0.03-0.1).

4. The preparation method according to claim 1, characterized in that In step (2), the mass concentration of the C-lignin mixture is 5-30%.

5. The preparation method according to claim 4, characterized in that In step (2), the volume of the C-lignin mixture is 1-20 mL.

6. The preparation method according to claim 1, characterized in that In step (2), the heating reaction temperature is 90-95°C and the time is 3-4 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that In step (2), the C-lignin mixture is added to the polyvinyl alcohol mixture prepared in step (1) in multiple times, where multiple times refers to more than 2 times.

8. A triboelectric film, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. The triboelectric film according to claim 8, characterized in that The thickness of the triboelectric film is 50-300 μm; and / or the tensile strength of the triboelectric film exceeds 40 MPa; and / or the fracture toughness of the triboelectric film exceeds 500 MJ / m 3 .

10. A self-powered intelligent electronic device, characterized in that: Comprising the triboelectric film according to claim 8 or 9.

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