A multi-structured design performance-enhanced triboelectric fiber yarn and a preparation method thereof

Abstract

The application discloses a multi-structure designed performance enhanced triboelectric fiber yarn and a preparation method thereof, and belongs to the field of intelligent fibers.The fiber yarn is a double-layer coaxial structure, and comprises a fiber conductive electrode, a charge capturing layer and a triboelectric layer.The fiber conductive electrode is a core layer, the charge capturing layer and the triboelectric layer are sequentially covered on the surface of the fiber conductive electrode as the core layer, and are coaxial with the fiber conductive electrode.The triboelectric fiber yarn forms a nano / micron interpenetrating structure on the contact surface of the charge capturing layer and the triboelectric layer, can effectively improve the charge capturing and storage enhancement capability, and adds thermal expansion microspheres in the triboelectric layer, so that the friction contact area is increased.Therefore, the multi-stage structure design has a performance enhancement effect, and realizes high output.

Description

Technical Field

[0001] This invention relates to the field of smart fibers, and particularly to a performance-enhancing triboelectric fiber yarn with a multi-structure design and its preparation method. Background Technology

[0002] With the development of flexible electronics and wearable technology, triboelectric nanogenerators have attracted widespread attention due to their ability to convert mechanical energy into electrical energy. Triboelectric fiber yarns, as a novel type of flexible energy harvesting and sensor, can be integrated into textiles to achieve self-powered sensing and human-computer interaction functions. However, existing triboelectric fiber yarns still face the following technical bottlenecks: ① Severe charge dissipation: Traditional triboelectric fibers are typically composed of conductive fibers and a polymer friction layer, lacking an effective charge capture mechanism. This leads to the easy dissipation of charge generated by friction through interfacial recombination or air conduction, limiting output performance. ② Limited contact area: Ordinary fiber surfaces are smooth or have only simple micron-level rough structures, resulting in a small friction contact area and limiting charge generation efficiency. ③ Weak interfacial bonding: The polymer friction layer and the electrode are usually in physical contact, which is prone to delamination or wear after long-term use, affecting the stability and durability of the device. Summary of the Invention

[0003] The problem to be solved by the present invention is to provide a performance-enhanced triboelectric fiber yarn, wherein the fiber yarn has a double-layer coaxial structure, including a fiber conductive electrode, a charge trapping layer, and a triboelectric layer; the fiber conductive electrode is a core layer, and the charge trapping layer and the triboelectric layer are sequentially covered on the surface of the fiber conductive electrode and are coaxial with the fiber conductive electrode.

[0004] Furthermore, nano- and micro-scale interpenetrating structures are formed at the contact surface between the charge trapping layer and the triboelectric layer.

[0005] Furthermore, the fiber conductive electrode is one of silver conductive sewing thread, silver wire, gold wire, copper wire, or other conductive wire.

[0006] Furthermore, the charge-trapping layer is a polyimide (PI) layer, which is formed by wrapping the polyimide (PI) material onto the surface of the fiber conductive electrode through a conjugated electrospinning process.

[0007] Furthermore, the polyimide (PI) layer has a disordered fibrous network structure and a porous surface.

[0008] Furthermore, the thickness of the polyimide (PI) layer is controlled by adjusting the electrospinning parameters, and the thickness ranges from 5 micrometers to 500 micrometers.

[0009] Furthermore, the triboelectric layer is formed by thermosetting polymer material doped with thermally expandable microspheres, with the doping concentration of the thermally expandable microspheres being 0.1-10 wt%.

[0010] Furthermore, the polymer material includes PDMS, Ecoflex, PU, ​​or rubber, the precursor viscosity of the polymer material is <500 cP, and it penetrates into the fiber pores of the polyimide (PI) layer to form a nano- and micro-scale interpenetrating structure.

[0011] Based on the triboelectric fiber yarn of the present invention, the present invention also provides a method for preparing the triboelectric fiber yarn, comprising the following steps:

[0012] Step 1: Mix polyimide (PI), anhydrous lithium chloride, and NMP and stir until homogeneous to obtain an electrospinning precursor solution. The mass ratio range is PI: anhydrous lithium chloride: NMP = (0.5-1.5):(0.05-0.15):(8-15).

[0013] Based on the electrospinning precursor solution, a polyimide (PI) layer is prepared on the surface of the fiber conductive electrode by a conjugate electrospinning process to form a PI-fiber conductive electrode; the polyimide (PI) layer serves as a charge trapping layer.

[0014] Step 2: Mix PDMS and its curing agent at a mass ratio of 10:1, then add 0.5%-2% by mass of thermally expandable microspheres, stir evenly, and obtain a thermally expandable microsphere PDMS mixture.

[0015] The PI-fiber conductive electrode is immersed in a thermally expanded microsphere PDMS mixture. An electric current is applied to the PI-fiber conductive electrode, and the Joule heat generated by the electric current causes the PDMS near the PI-fiber conductive electrode to be uniformly solidified on the surface of the PI-fiber conductive electrode. The PI-fiber conductive electrode is removed from the mixture and the electric current is applied again, so that the PDMS on the surface of the PI-fiber conductive electrode is completely solidified and the microspheres are fully expanded.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0017] (1) The triboelectric fiber yarn of the present invention has a PI layer added between the electrode and the microstructure triboelectric layer by electrospinning, which can capture charge and prevent charge dissipation.

[0018] (2) The triboelectric fiber yarn of the present invention has a polymer / PI composite interface structure with a nano / micro interpenetrating structure that can effectively improve the charge capture and storage enhancement capabilities.

[0019] (3) Thermally expanded microspheres were added to the triboelectric layer, which gave the surface a rough structure and increased the frictional contact area.

[0020] Therefore, this invention, through multi-level structural design (conductive electrode + charge trapping layer + microstructure triboelectric layer) and nano / micro interpenetrating interface, has performance enhancement effect, achieves high output and long life triboelectric performance, and is suitable for wearable human-computer interaction applications, and is used in human-computer interaction in the form of fiber sensor. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the triboelectric fiber yarn structure;

[0022] Figure 2 This is a schematic diagram of the polymer / PI composite interface structure with a nano / micro interpenetrating structure;

[0023] Figure 3 This is a comparison chart of output voltage signals from different functional layers. Detailed Implementation

[0024] The purpose of this invention is to provide a performance-enhancing triboelectric fiber yarn with a multi-structure design, such as... Figure 1 As shown, the core layer consists of a fiber conductive electrode, a charge trapping layer, and a microstructure triboelectric layer, respectively. A composite interface structure with nano / micro interpenetrating structure is formed at the contact surface between the charge trapping layer and the microstructure triboelectric layer, which can enhance the triboelectric output performance and enable human-computer interaction when combined with ordinary clothing.

[0025] In this embodiment, the fiber conductive electrode is one of silver conductive sewing thread, silver wire, gold wire, copper wire, or other conductive wire.

[0026] The charge-capturing layer is formed by wrapping polyimide (PI) material onto the surface of a fiber conductive electrode using a conjugated electrospinning process. The PI layer has a disordered network fiber structure and a porous surface. The thickness can be controlled by adjusting the electrospinning parameters, and the thickness ranges from 5 micrometers to 500 micrometers.

[0027] The microstructured triboelectric layer is formed by thermosetting polymer-doped thermally expandable microspheres. In this embodiment, the microstructured triboelectric layer is a polymer thermally expandable microsphere layer. The polymer material includes one of PDMS, Ecoflex, PU, ​​and rubber. The doping concentration of the thermally expandable microspheres is 0.1-10 wt%.

[0028] The precursor of the polymer material has a viscosity of <500 cP and penetrates into the pores of the PI fiber to form a nano- and micro-scale interpenetrating structure, such as... Figure 2As shown, the nano- and micro-scale interpenetrating structure refers to a structure that includes both nano- and micro-scale interpenetrating structures. The interpenetrating structure is a composite interface structure formed by the mutual penetration and interweaving of two or more materials at the microscale (nano- and micro-scale). In this invention, the nano- and micro-scale interpenetrating structure refers to a composite interface structure formed by the mutual penetration and interweaving of a charge-trapping layer and a triboelectric layer at the microscale (nano- and micro-scale). The penetration depth of this nano- and micro-scale interpenetrating structure accounts for 20-60% of the PI fiber thickness.

[0029] The enhanced performance principle of the triboelectric fiber yarn of this invention is mainly due to three reasons: ① The outer polymer-doped thermally expandable microspheres create a micro-protrusion structure, enhancing the triboelectric contact area; ② The addition of a PI layer through electrospinning between the electrode and the outer microstructure triboelectric layer effectively captures charge and hinders charge dissipation. First, the high dielectric constant of PI and the deep-level traps in its molecular structure strongly bind the charge, preventing free charge migration; second, the porous PI fiber network formed by electrospinning provides a larger specific surface area and more charge-capturing sites, while physically blocking charge diffusion. These characteristics collectively enhance the charge capture and storage capacity, thereby improving triboelectric performance; ③ The polymer / PI composite interface structure with nano- and micro-interpenetrating structures effectively improves the charge capture and storage enhancement capacity. This structure, on the one hand, significantly increases the contact area between the polymer and PI through physical anchoring, providing more interfacial active sites for charge capture; on the other hand, the nano- and micro-level topological entanglements in the interpenetrating structure can form multiple potential wells, effectively limiting the longitudinal migration and lateral diffusion of charge.

[0030] like Figure 3 As shown, the output voltage performance of three types of triboelectric fiber wires is compared: ① a triboelectric fiber wire containing only a conductive electrode and a polymer layer; ② a triboelectric fiber wire containing a fiber conductive electrode and a polymer thermally expanded microsphere layer; and ③ the enhanced triboelectric fiber wire proposed in this invention (fiber conductive electrode + PI layer + polymer thermally expanded microsphere layer). Experimental results show that the enhanced triboelectric fiber wire of this invention, due to the introduction of the PI layer and the nano / micro interpenetrating structure, significantly improves charge capture efficiency and storage capacity. Its output voltage signal intensity is 2-3 times higher than that of the triboelectric fiber wire with only a polymer layer and 2-3 times higher than that of the triboelectric fiber wire with only a polymer thermally expanded microsphere layer. This verifies the key role of the composite interface structure of the nano / micro interpenetrating structure in suppressing charge dissipation and enhancing triboelectric output. It intuitively demonstrates the technical advantages of this invention in achieving performance enhancement through multi-level structural design, providing a reliable basis for wearable energy harvesting and human-computer interaction applications.

[0031] The triboelectric fiber yarn can be sewn onto the surface of everyday fabrics such as cloth and clothing for human-computer interaction control. When touched by a human hand, the triboelectric fiber yarn outputs an electrical signal based on the principle of triboelectricity. After signal acquisition and processing, this signal can be converted into human-computer interaction control commands. It can control the switching of everyday household appliances, such as lights and speakers, and can also control the movement of characters in virtual scenes.

[0032] This invention also provides a method for preparing triboelectric fiber yarn, comprising the following steps:

[0033] Step 1: A charge-capturing layer is formed by wrapping polyimide (PI) material onto the surface of a fiber conductive electrode using a conjugate electrospinning process. Specifically:

[0034] Step 1.1. Preparation of precursor solution;

[0035] A precursor solution was prepared using polyimide (PI): anhydrous lithium chloride (LiCl): NMP, with a mass ratio ranging from (0.5-1.5):(0.05-0.15):(8-15).

[0036] In this embodiment, 1g of polyimide PI, 0.1g of anhydrous lithium chloride and 10ml of NMP (N-methylpyrrolidone) solution were mixed and the solution was stirred at 100 degrees Celsius for 24h on a magnetic stirrer to prepare a polyimide PI electrospinning precursor solution.

[0037] Steps 1 and 2: Conjugate electrospinning;

[0038] Conjugate electrospinning was performed using an electrospinning machine under normal temperature and humidity conditions. The PI electrospinning precursor solution was loaded into two 10 mL plastic syringes, each equipped with a stainless steel spinneret with an inner diameter of 0.41 mm. The tip of the left spinneret was connected to an applied voltage of +17.0 kV, and the tip of the right spinneret was also connected to an applied voltage of +17.0 kV. The solution feed rate was controlled at 1 mL·h⁻¹, and the receiving distance was maintained at 100 mm. The nanofibers were received by a rotating collector, and PI was coated onto silver-plated yarn to form PI-silver-plated yarn functional fibers. The rotating collector speed was 500 r·min⁻¹, and the fiber winding speed was set to 2 r·min⁻¹ (the PI layer thickness could be controlled by changing the fiber winding speed and the solution feed rate).

[0039] Step 2, PDMS coating and curing;

[0040] First, mix PDMS and its curing agent at a mass ratio of 10:1, then add 0.5%-2% by mass of thermally expandable microspheres, place the mixture in a planetary stirrer, and stir for 2 minutes to obtain a thermally expandable microsphere-PDMS mixture.

[0041] The thermally expanded microsphere PDMS mixture was poured into a pre-prepared mold, and then the PI-silver-plated yarn was immersed in the mixture. Next, the PI-silver-plated yarn was energized with a power supply set to 3W. The Joule heat generated by the energization caused the PDMS near the yarn to be uniformly cured onto the yarn surface. After energizing for 5 minutes, the yarn was removed, and energization was continued for another 10 minutes. Once the PDMS on the functional yarn was completely cured and the microspheres had fully expanded, the yarn was collected.

Claims

1. A triboelectric fiber yarn, characterized in that, The fiber yarn has a double-layer coaxial structure, including a fiber conductive electrode, a charge trapping layer and a triboelectric layer; The fiber conductive electrode is the core layer, and the charge trapping layer and the triboelectric layer are sequentially covered on the surface of the fiber conductive electrode and are coaxial with the fiber conductive electrode. A nano- and micro-scale interpenetrating structure is formed at the contact surface between the charge trapping layer and the triboelectric layer. The charge-trapping layer is a polyimide (PI) layer, which is formed by wrapping the polyimide (PI) material onto the surface of the fiber conductive electrode through a conjugated electrospinning process; the polyimide (PI) layer has a disordered network fiber structure and a porous surface. The triboelectric layer includes thermally expandable microspheres, which are formed by thermal curing polymer material doped with thermally expandable microspheres; the precursor viscosity of the polymer material is <500 cP, and the polymer material penetrates into the fiber pores of the polyimide (PI) layer to form the nano- and micro-scale interpenetrating structure. The method for preparing the triboelectric fiber yarn includes the following steps: Step 1: Mix polyimide (PI), anhydrous lithium chloride, and NMP and stir until homogeneous to obtain an electrospinning precursor solution. The mass ratio of polyimide (PI), anhydrous lithium chloride, and NMP is (0.5-1.5):(0.05-0.15):(8-15). Based on the electrospinning precursor solution, a polyimide (PI) layer is prepared on the surface of the fiber conductive electrode by a conjugate electrospinning process to form a PI-fiber conductive electrode. The polyimide (PI) layer serves as a charge trapping layer. Step 2: Mix PDMS and its curing agent at a mass ratio of 10:1, then add 0.5%-2% by mass of thermally expandable microspheres, stir evenly, and obtain a thermally expandable microsphere PDMS mixture. The PI-fiber conductive electrode is immersed in a thermally expanded microsphere PDMS mixture. An electric current is applied to the PI-fiber conductive electrode, and the Joule heat generated by the electric current solidifies the PDMS around the PI-fiber conductive electrode onto the surface of the PI-fiber conductive electrode. The PI-fiber conductive electrode is removed from the mixture and the electric current is applied again, so that the PDMS on the surface of the PI-fiber conductive electrode is completely solidified and the microspheres are fully expanded.

2. The triboelectric fiber yarn according to claim 1, characterized in that, The penetration depth of nano- and micro-scale interpenetrating structures accounts for 20-60% of the thickness of PI fibers.

3. The triboelectric fiber yarn according to claim 1, characterized in that, The fiber conductive electrode is one of the following: silver conductive sewing thread, silver wire, gold wire, copper wire, or other conductive wire.

4. The triboelectric fiber yarn according to claim 1, characterized in that, The thickness of the polyimide (PI) layer is controlled by adjusting the electrospinning parameters, and the thickness ranges from 5 micrometers to 500 micrometers.

5. The triboelectric fiber yarn according to claim 1, characterized in that, The polymer material includes PDMS, Ecoflex, PU, ​​or rubber.

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