A method for preparing a hydrophobic sisal cellulose paper triboelectric material

Abstract

The application discloses a preparation method of a hydrophobic sisal cellulose paper triboelectric material. After sisal fibers are treated by a hydrothermal method, the sisal fibers are filtered, washed and dried to obtain sisal cellulose, the obtained sisal cellulose is dispersed in deionized water, and then the sisal cellulose paper (SCP) with a thickness of 80-160 microns is prepared through suction filtration film formation, hydraulic rolling forming and drying. The SCP is hydrophobically modified by using polymers such as ABS, PLA and PMMA, the hydrophobically modified SCP can be used as a friction material of a liquid-solid friction nanogenerator, and can be used for raindrop and ocean energy collection, wave sensor, distress signal transmitter, weather monitoring, self-driven irrigation and self-activated anti-fouling system, and the application field of the cellulose-based friction nanogenerator and sisal is widened.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing a hydrophobic sisal fiber paper triboelectric material, and belongs to the field of liquid-solid contact electrification, triboelectric nanogenerator, energy harvesting and sensor. BACKGROUND

[0002] Triboelectric nanogenerator (TENG) is the first invention that uses the coupling effect of contact electrification and electrostatic induction to effectively convert mechanical energy into electrical energy. As a power source, it can instantly drive hundreds of LED lights, charge lithium-ion batteries, power wireless sensors and commercial mobile phones. In addition, compared with solar energy, it can utilize mechanical energy such as sea waves, tides and rainwater, which is largely unaffected by day and night, seasons, weather and climate (Zhai Y M. Optimization of biocompatible triboelectric nanogenerator structure and exploration of its sensor applications[D]. Tianjin University of Technology, 2019.). With the increasing popularity of TENG, its research scope is gradually expanding. Not only can it collect energy from the environment such as wave energy, wind energy and raindrop energy, but also can utilize the mechanical energy generated by human movement. Under relatively dry conditions, TENG can work normally, but when working in a humid environment, the performance of TENG will be greatly reduced (Li L, Wang X, Zhu P, et al. The electron transfer mechanism between metal and amorphous polymers in humidity environment for triboelectric nanogenerator[J]. Nano Energy, 2020, 70: 104476.). So far, the design of TENG is to operate between solid materials under dry conditions, and the working efficiency and performance are best. However, how to use solid-liquid contact energy is a great challenge we are facing today.

[0003] The continuous process of liquid contact and separation from solid surface and the net charge generated thereby is called "liquid-solid contact electrification" (Dong Y, Wang N, Yang D, et al. Robust Solid-Liquid Triboelectric Nanogenerators: Mechanisms, Strategies and Applications [J]. Advanced Functional Materials, 2023: 2300764.), in which, in order to separate the aqueous liquid from the surface of the material, it is one of the key characteristics to make the solid surface hydrophobic to realize the liquid-solid contact electrification. In the field of liquid-solid contact electrification, researchers study materials with hydrophobic ability to obtain TENG with stable performance and more extensive application scenarios.

[0004] Cellulose as a green and flexible material is widely used as a friction material in TENGs, but the output performance of TENGs will decrease in a humid environment, and because cellulose has hydrophilicity, it limits the development of "liquid-solid contact" TENGs (Trentin L N, Pereira C S, Silveira R L, et al. Nanoscale wetting of crystalline cellulose[J]. Biomacromolecules, 2021, 22(10): 4251-4261.). Sisal has the characteristics of short growth cycle, low price and wide planting area, and its main chemical components are cellulose (60-70%), hemicellulose (12-15%), lignin (8-10%) and a small amount of pectin, wax and water-soluble substances (Furlan D M, Morgado D L, Oliveira A J a D, et al. Sisal cellulose and magnetite nanoparticles: formation and properties of magnetic hybrid films[J]. Journal of Materials Research and Technology, 2019, 8(2): 2170-2179.). Therefore, sisal fiber can be used as a high-quality cellulose source with wide sources and low price. Sisal cellulose paper (SCP) has strong hydrophilicity and no hydrophobic ability, but has rough surface and porous characteristics, and can be made hydrophobic by adsorbing hydrophobic polymers (Jie Y, Zhu H, Cao X, et al. One-piece triboelectric nanosensor for self-triggered alarm system and latent fingerprint detection[J]. ACS Nano, 2016, 10(11): 10366-10372.).

[0005] ABS is a terpolymer of acrylonitrile (A), butadiene (B), and styrene (S), which has the properties of chemical corrosion resistance, heat resistance, high elasticity and toughness, and processing characteristics of thermoplastic plastics (Ding J, Lu X B, Zeng L X, et al. Research on chromium-free manganese dioxide micro-etching and roughening of ABS engineering plastic surface[J]. Electroplating and Finishing, 2012, 31(6): 27-30.). Polylactic acid (PLA) is a hydrophobic polymer and has good compatibility modification (Babu A, Periasamy J, Gunasekaran A, et al. Polyethylene glycol-modified gelatin / polylactic acid nanoparticles for enhanced photodynamic efficacy of a hypocrellin derivative in vitro[J]. Journal of biomedical nanotechnology, 2013, 9(2): 177-192.). Poly(methyl methacrylate) (PMMA) is also an engineering material with good hydrophobicity and biocompatibility (Wang Q, Li K, Wu Y H, et al. High-hydrophobic CsPbBr3

[0006] nanocrystal poly(methyl methacrylate) composite fiber film prepared by electrospinning[J]. Materials Review, 2022, 36(16): 250-254).

[0007] Considering that hydrophobic or superhydrophobic solid surfaces have low surface energy, good durability, stable output, antifouling and anti-sticking, and strong environmental adaptability, etc., the surface of the friction material is modified to obtain a surface with different wettability, which has become one of the important factors for studying the output performance of SL-TENG wettability (Dong Y, Wang N, Yang D, et al. Robust Solid-Liquid Triboelectric Nanogenerators: Mechanisms, Strategies and Applications[J]. Advanced Functional Materials, 2023: 2300764. Xinyue Wu, Xunjia Li, Jianfeng Ping, et al. Recent advances in water-driven triboelectric nanogenerators based on hydrophobic interfaces[J]. Nano Energy, 2021, 90(8): 106592). The present application starts from the wettability angle, and uses hydrophobic polymers such as ABS, PLA and PMMA to modify the hydrophilic SCP by physical modification method, as the friction material of the liquid-solid friction nanogenerator (LS-TENG), so that the SCP-TENG can be applied to raindrop and ocean energy collection, wave sensor, distress signal transmitter, weather monitoring, self-driven irrigation and self-activated anti-pollution system, etc. Multiple scenes, broaden the application scenarios of cellulose-based TENG and the application field of sisal. SUMMARY

[0008] The purpose of the present application is to provide a method for making hydrophobic sisal cellulose paper TENG friction material.

[0009] In order to achieve the above-mentioned purpose, the specific preparation method involved in the present application is as follows:

[0010] (1) After washing the sisal fiber raw material with water, dry the moisture in the oven at 50-70℃, and finally cut it into pieces for use.

[0011] (2) Take 40-60 g of sisal fiber obtained in step (1) and put it into a 1000 mL high-temperature high-pressure reaction kettle, add 700 mL of NaOH solution with a concentration of 2-3 mol / L, assemble the high-temperature reaction kettle, put it into the oven, and heat it to 150-180℃ for 12-16h.

[0012] (3) After the reaction in step (2) is completed, the reaction product is filtered after cooling to room temperature, and the filter residue is repeatedly washed with deionized water until the color of the filtrate does not change and the obtained sisal cellulose is dried in a vacuum oven at 60-70 DEG C until the weight is constant, thereby obtaining the sisal cellulose.

[0013] (4) The sisal cellulose prepared in step (3) is dispersed in deionized water, and a sisal cellulose paper (SCP) with a thickness of 80-160 microns is prepared by suction filtration, hydraulic rolling and drying.

[0014] (5) A polymer solution with a concentration of 8-12 g / L is prepared by taking a polymer with hydrophobicity as a solute and dichloromethane as a solvent.

[0015] (6) The SCP prepared in step (4) is immersed in the polymer solution prepared in step (5) for 15-20 minutes, taken out, and then immersed in pure dichloromethane (CH2Cl2) for 10 minutes to remove excess polymer, and then placed in an oven at 60-75 DEG C for constant temperature drying, thereby obtaining a hydrophobic SCP. A contact angle tester (JY-PHb) is used to test the contact angle of the obtained material.

[0016] (7) The polymer-modified hydrophobic SCP prepared in step (6) is cut to a certain size as a TENG rubbing material. A double-sided tape is attached to an acrylic support substrate, and an electrode layer material, preferably a copper foil, is cut to the same size. The electrode layer material is cut into interdigital electrodes with an interdigital width of 3-6 mm and an interdigital spacing of 1-3 mm. The interdigital electrodes are attached to the back of the hydrophobic SCP, and the prepared interdigital electrodes and the hydrophobic SCP rubbing layer are attached to the double-sided tape. A wire is connected between the double-sided tape and the electrode layer to complete the circuit, thereby obtaining the interdigital electrode hydrophobic SCP-TENG. An electrometer is used to test the electrical output performance of the hydrophobic SCP-TENG.

[0017] The polymer is ABS, PLA or PMMA, but is not limited to these three polymers. The electrode layer is not limited to a copper foil, and can also be a good conductive material such as aluminum, silver, gold, nickel, liquid metal, graphene, carbon nanotube, etc.

[0018] The beneficial effects of the present application are:

[0019] The present application uses natural fibers as raw materials to prepare a sisal cellulose paper with hydrophobicity, which can be used as a rubbing material for LS-TENG and can be applied to raindrop and ocean energy collection, wave sensor, distress signal transmitter, weather monitoring, self-driven irrigation and self-activated anti-fouling system, thereby widening the application scenarios of cellulose-based TENG and the application field of sisal. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a scanning electron microscope image of SCP modified with ABS described in Example 1;

[0021] Figure 2 is a water contact angle image of SCP modified with ABS described in Example 1;

[0022] Figure 3 is the output charge amount of the hydrophobic TENG with interdigital electrodes made of SCP modified with ABS described in Example 1 under simulated different rainfall.

[0023] Figure 4 is a scanning electron microscope image of SCP modified with PLA described in Example 2;

[0024] Figure 5 is a water contact angle image of SCP modified with PLA described in Example 2;

[0025] Figure 6 is the output charge amount of the hydrophobic TENG with interdigital electrodes made of SCP modified with PLA described in Example 2 under simulated different rainfall. DETAILED DESCRIPTION

[0026] In order to make the present application clearer, the following will further describe the present application in conjunction with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0027] Example 1:

[0028] (1) After washing the sisal fiber raw material with clean water, dry the moisture in the 60 ℃ oven, and finally cut into 20 mm small pieces for standby.

[0029] (2) Take 50 g of sisal fiber obtained in step (1) and put it into a 1000 mL high-temperature and high-pressure reaction kettle, add 700 mL of NaOH solution with a concentration of 2.5 mol / L, assemble the high-temperature reaction kettle, put it into the oven, and heat to 160 ℃ for 12 h.

[0030] (3) After the reaction in step (2) is completed, cool to room temperature, filter the reaction product, take the filter residue part, wash repeatedly with deionized water, wash until the filtrate color does not change, and show neutral, dry the obtained sisal cellulose in a 65 ℃ vacuum oven to constant weight, and obtain sisal cellulose.

[0031] (4) Disperse the sisal cellulose prepared in step (3) in deionized water, form a film by suction filtration, form and dry by hydraulic pressing to form a sisal cellulose paper (SCP) with a thickness of 140 microns, and the morphology thereof is shown in Figure 1 .

[0032] (5) ABS as solute, dichloromethane as solvent, to prepare a concentration of 10 g / L ABS solution.

[0033] (6) The SCP prepared in step (4) is immersed in the ABS solution prepared in step (5) for 15 minutes, then taken out and immersed in pure dichloromethane (CH2Cl2) for 10 minutes to remove excess polymer, and placed in an oven at 60-75 ℃ for constant temperature drying. After drying, the ABS modified SCP is obtained. The contact angle of the obtained material is tested by a contact angle tester (JY-PHb), and the contact angle is 115.1° (θ = 115.1°, h = 2.5 mm, r = 2.5 mm), indicating that the ABS modified SCP has good hydrophobicity. Figure 2

[0034] (7) The SCP obtained in step (6) is cut into 6×6 cm 2 size for standby, double-sided tape is pasted on the supporting substrate, conductive copper foil is cut into 5×5 cm 2 specification, and then cut into interdigital electrodes with a finger width of 5 mm and a finger spacing of 1 mm. The interdigital electrodes are pasted on the back of the SCP, and the prepared interdigital electrodes and the rubbing layer are attached to the double-sided tape. The wires are connected between the double-sided tape and the electrode layer to complete the circuit, and the ABS modified SCP-TENG with interdigital electrodes is obtained. The ABS modified SCP-TENG is connected to the static tester through the wires, and the energy collection is simulated by raindrops. When the raindrop flow rate is 14.4 ml / s, the raindrops are perpendicular to the surface of the SCP-TENG, and the included angle between the SCP-TENG and the ground is 60°, the ABS modified SCP-TENG has the maximum electrical output performance, the short-circuit current is 14.8 μA, the open-circuit voltage is 16 V, and the charge quantity is 81 nC (Q = 81 nC, V = 16 V, I = 14.8 μA). Figure 3

[0035] Example 2:

[0036] (1) After the sisal fiber raw material is washed with water, it is placed in a 60 ℃ oven to dry the moisture, and finally cut into 20 mm small sections for standby.

[0037] (2) Take 50 g of sisal fiber obtained in step (1) and put it into a 1000 mL high-temperature and high-pressure reaction kettle, add 700 mL of 2.5 mol / L NaOH solution, assemble the high-temperature reaction kettle, and put it into an oven, heat to 160 ℃ and keep for 12 h.

[0038] (3) After the reaction in step (2) is completed, cool to room temperature, filter the reaction product, and wash the filter residue with deionized water repeatedly until the filtrate color does not change, and the obtained sisal cellulose is dried in a 65 ℃ vacuum oven to constant weight, and the sisal cellulose is obtained. ​​

[0039] (4) The sisal cellulose prepared in step (3) was dispersed in deionized water, and a film was formed by suction filtration, liquid pressure rolling and drying to obtain a sisal cellulose paper (SCP) with a thickness of 140 microns. The morphology of the SCP was observed by scanning electron microscopy as shown in Figure 4 .

[0040] (5) A PLA solution with a concentration of 10 g / L was prepared using PLA as the solute and dichloromethane as the solvent.

[0041] (6) The SCP prepared in step (4) was immersed in the PLA solution prepared in step (5) for 15 minutes, then taken out and immersed in pure dichloromethane (CH2Cl2) for 10 minutes to remove excess polymer. The material was then dried in an oven at a constant temperature of 60-75 °C. After drying, a PLA-modified SCP was obtained. The contact angle of the material was measured using a contact angle meter (JY-PHb), and the contact angle was measured to be 110.9° (θ Figure 5 ), indicating that the PLA-modified SCP has good hydrophobicity.

[0042] (7) The PLA-modified SCP obtained in step (6) was cut into 6×6 cm 2 size for use. Double-sided tape was attached to the support substrate, and conductive copper foil was cut into a 5×5 cm 2 specification, and then cut into interdigital electrodes with a finger width of 5 mm and a finger spacing of 1 mm. The interdigital electrodes were attached to the back of the SCP, and the prepared interdigital electrodes and the rubbing layer were attached to the double-sided tape. A wire was connected between the double-sided tape and the electrode layer to complete the circuit, and a PLA-modified SCP-TENG with interdigital electrodes was obtained. The PLA-modified SCP-TENG was connected to an electrostatic tester through a wire, and energy harvesting was simulated by raindrops. When the raindrop flow rate was 14.4 ml / s, the raindrops were perpendicular to the surface of the SCP-TENG, and the angle between the SCP-TENG and the ground was 60°, the SCP-TENG had the maximum output performance, with a short-circuit current of 11.8 μA, an open-circuit voltage of 7 V, and a charge of 59 nC (Q Figure 6 ).

Claims

1.A method for preparing a hydrophobic sisal fiber paper triboelectric material, the method comprising the following steps: (1) washing sisal fiber raw materials with water, drying the sisal fiber raw materials in an oven at 50-70 ℃, and then cutting the sisal fiber raw materials into pieces; (2) placing 40-60 g of the sisal fiber pieces obtained in step (1) into a 1000 mL high-temperature and high-pressure reactor, adding 700 mL of a NaOH solution with a concentration of 2-3 mol / L, assembling the high-temperature and high-pressure reactor, and placing the high-temperature and high-pressure reactor in an oven, and then heating the high-temperature and high-pressure reactor to 150-180 ℃ and maintaining the temperature for 12-16 h; (3) after the reaction in step (2) is completed, cooling the high-temperature and high-pressure reactor to room temperature, filtering the reaction product, repeatedly washing the filtered residue with deionized water until the pH value of the filtrate is 7, and drying the obtained sisal cellulose in a vacuum oven at 60-70 ℃ until the weight of the sisal cellulose is constant; (4) dispersing the sisal cellulose prepared in step (3) in deionized water, and then forming a film by suction filtration, and then performing hydraulic pressing to form a sheet, and then drying the sheet to obtain a sisal cellulose paper with a thickness of 80-160 microns; (5) preparing a polymer solution with a concentration of 8-12 g / L by using ABS, PLA or PMMA as a hydrophobic polymer and using dichloromethane as a solvent; (6) immersing the sisal cellulose paper prepared in step (4) in the polymer solution prepared in step (5), taking out the sisal cellulose paper after 15 minutes of immersion, immersing the sisal cellulose paper in pure dichloromethane for 10 minutes to remove excess polymer, and then placing the sisal cellulose paper in an oven at 60-75 ℃ for constant temperature drying, and obtaining a hydrophobic sisal fiber paper triboelectric material with a static water contact angle of ≥110.9°. 2.Use of the hydrophobic sisal fiber paper triboelectric material prepared by the method of claim 1 in a liquid-solid contact triboelectric nanogenerator, wherein the hydrophobic sisal fiber paper is used as a friction layer in contact with liquid for raindrop or water flow energy harvesting. 3.The hydrophobic sisal fiber paper triboelectric material prepared by the method of claim 1, wherein the hydrophobic sisal fiber paper triboelectric material has a static water contact angle of ≥110.9°. 4.The use of claim 2, wherein the liquid-solid contact triboelectric nanogenerator comprises interdigital electrodes arranged on the back surface of the hydrophobic sisal fiber paper, each finger of the interdigital electrodes has a width of 3-6 mm, the interdigital electrodes have a finger spacing of 1-3 mm, and the interdigital electrodes are connected to an external circuit through a wire; and the interdigital electrodes are made of a conductive material. ​ ​ ​ ​ ​ ​

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