An integrally biodegradable triboelectric fiber and preparation and application thereof

Abstract

The present application relates to a kind of whole-body biodegradable triboelectric fiber and its preparation and application, and the triboelectric fiber includes helical electrical core layer and skin layer;Wherein helical electrical core layer includes bioabsorbable conductive silk and biodegradable polymer dielectric fiber layer;The skin layer is biodegradable thermoplastic material.The fiber of the present application is used for micro-nano energy collection and in-vivo ligament suture.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of triboelectric materials, and particularly relates to a triboelectric fiber that can be biodegraded as a whole and preparation and application thereof. BACKGROUND

[0002] As a new energy, triboelectric nanogenerator (TENG) can convert mechanical energy into electrical energy by using triboelectric and electrostatic coupling effect. In recent years, it has been widely used in self-powered systems due to its low cost and good adaptability. Generally, two-dimensional thin film TENG has a larger area and poor flexibility during use, and cannot be directly used in some implantable applications [Advanced Materials, 2021, 33(48): 2104175]. One-dimensional fiber type TENG has better flexibility and applicability than two-dimensional materials, and is more suitable for various scene applications, but its processing is more difficult. At present, fiber type TENG prepared by various spinning processes, including wet spinning, melt spinning, electrospinning, etc., is being widely studied. In addition, optimization of traditional spinning processes and exploration of new spinning processes are also becoming the focus of current research.

[0003] The fiber TENG device mainly includes an external friction layer and an internal electrode layer, but most of the materials used to prepare the fiber TENG are difficult to degrade, including polytetrafluoroethylene (PTFE), polydimethylsiloxane (PDMS), polyimide (PI), silver electrode, etc. Wang et al. [Advanced Energy Materials, 2022, 12(31): 2201288] reported a three-dimensional woven stretchable layered interlocking fancy yarn triboelectric nanogenerator. The fiber is composed of traditional nylon and polyester fibers and silver-plated conductive yarn. The use of such non-degradable materials still puts a lot of pressure on the environment, so it is urgent to use biodegradable metals and polymers to replace non-degradable electrode layers and friction layers to prepare fiber TENG. Most biodegradable polymers are rigid polymers, and processing them into multi-layer coaxial fibers will become hard and brittle, so a suitable spinning process and the thickness of each layer need to be controlled to obtain more flexible fibers to be suitable for more scenarios. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a triboelectric fiber that can be biodegraded as a whole and preparation and application thereof.

[0005] The triboelectric fiber of the present application comprises a spiral electrical core layer and a skin layer; wherein the spiral electrical core layer comprises a bioabsorbable conductive filament and a biodegradable polymer dielectric fiber layer; and the skin layer is a biodegradable low-melting-point thermoplastic material.

[0006] The bioabsorbable conductive wire is a magnesium wire; the biodegradable polymer dielectric fiber is a polylactic acid (PLA) dielectric fiber; and the biodegradable thermoplastic material is a poly-caprolactone (PCL) melt-spun solid skin layer.

[0007] The diameter of the bioabsorbable conductive wire in the spiral electrical core layer is 100-300 um, the thickness of the biodegradable polymer dielectric fiber layer is 50-300 um, and the thickness of the skin layer is 50-300 um.

[0008] The present application also provides a preparation method of the triboelectric fiber.

[0009] (1) conjugate spinning of a biodegradable polymer spinning solution and twisting by a winding roller to the surface of the bioabsorbable conductive wire to obtain an electrical core layer;

[0010] (2) drawing the electrical core layer obtained in step (1) into a melt of a biodegradable thermoplastic material, and drawing out to obtain the triboelectric fiber.

[0011] The preferred mode of the preparation method is as follows:

[0012] In step (1), the bioabsorbable conductive wire is a magnesium wire with a diameter of 100-300 um, the biodegradable polymer is polylactic acid (PLA), and the mass percentage concentration of the spinning solution is 10%-15%; and the PLA thickness in the obtained Mg@PLA fiber is 50-300 um.

[0013] In step (1), the two-pole spinneret in the conjugate spinning is respectively provided with positive and negative high voltage, the spinning solution becomes dielectric nanofiber under the electrostatic force stretching action, and is twisted to the surface of the magnesium fiber core by a winding roller; wherein the positive and negative high voltage ranges from +9 to +12 kV and from -9 to -12 kV, respectively, the speed of the winding roller is 300-500 r / min, and the speed of the collection roller is 1.5-6 r / min.

[0014] In step (2), the biodegradable thermoplastic material is poly-caprolactone (PCL).

[0015] In step (2), the heating ring is connected in series as a melting cavity, the biodegradable thermoplastic material is loaded into the glass cavity and melted in the central heating ring, the electrical core layer enters from the upper end and is drawn out from the metal spinning needle at the bottom of the cavity, and the skin layer firmly covers the core layer after stretching and natural cooling.

[0016] The temperature of the heating ring is 90-150℃, the stretching speed is 8-10 r / min, and the inner diameter of the metal spinning needle is 250-600 um.

[0017] The thickness of the skin layer (PCL) in the triboelectric fiber is 50-300 um.

[0018] The device used in the preparation method of the present application comprises a conjugate spinning part and a melt spinning part; wherein the conjugate spinning part comprises a winding roller and two jet orifices arranged on both sides of the winding roller; the two jet orifices are respectively provided with positive and negative high pressure; the melt spinning part comprises a glass cavity, a heating ring is arranged outside the glass cavity in series, and a metal spinning needle is arranged at the outlet of the glass cavity; wherein the conjugate spinning part and the melt spinning part are connected through the drawn fiber.

[0019] In the present application, the drawn bioabsorbable conductive wire is arranged in the center of the winding roller, the biodegradable polymer spinning solution is spun through the conjugate spinning and twisted through the winding roller to the surface of the bioabsorbable conductive wire, the biodegradable thermoplastic material is loaded into the glass cavity and placed in the central melting of the heating ring, the electrical core layer enters from the upper end of the glass cavity, is drawn through the melted biodegradable thermoplastic material, and is drawn out from the metal spinning needle at the bottom of the cavity, thereby obtaining a triboelectric fiber.

[0020] The triboelectric fiber of the present application is applied to small equipment energy supply or surgical suture, such as in vivo ligament suture.

[0021] In the present application, the spiral electrical core layer comprises bioabsorbable conductive magnesium wire and biodegradable polylactic acid (PLA) dielectric nanofiber, and the hollow fiber skin layer is biodegradable low-melting-point thermoplastic polycaprolactone (PCL). The preparation method comprises the following steps: taking magnesium wire as an internal electrode, using conjugate spinning for processing, tightly wrapping the spiral polylactic acid nanofiber around the magnesium electrode, using PCL with low melting point to melt in the customized glass cavity in the central heating ring, and then drawing the core layer out of the cavity to obtain a skin-core fiber. Compared with the traditional coaxial melt skin layer, the single-axis melt extraction method is combined with the core layer more firmly. The fiber selects biodegradable polymers with the largest difference in triboelectric negative polarity, so that the output of the fiber can be maximized. Meanwhile, the three materials are all rigid materials, but through the combination of control of fiber fineness and improved spinning process, the fiber has excellent flexibility and bendability and good strength, replacing the defects of the traditional triboelectric layer and electrode layer that are not degradable. A triboelectric fiber that can be biodegraded as a whole is prepared, and the fiber is used for micro-nano energy collection and in vivo ligament suture.

[0022] Advantages

[0023] (1) In the present invention, magnesium wire, as a metal that can be absorbed in the body, is introduced as the electrode material of the triboelectric fiber, replacing inert metals, including silver (Ag), gold (Au), platinum (Pt), etc., and metal-plated conductive fibers, such as silver-plated nylon fiber (Ag@PA), and other non-degradable electrode materials, thereby laying a good foundation for achieving biodegradation.

[0024] (2) The present invention introduces polylactic acid and polycaprolactone, two biodegradable polymers with the largest difference in triboelectricity, which have better output performance. The prepared Mg@PLA / PCL triboelectric fibers have an adjustable diameter of 150-600 μm. In addition, the materials used in the present invention are low-cost, easy to operate, and have mild experimental conditions, which can achieve continuous production.

[0025] (3) The Mg@PLA / PCL triboelectric fibers prepared in this invention can be used to power small microelectronic devices and charge commercial capacitors, enabling small-scale energy supply. Furthermore, due to their varying diameters, they can be used as surgical sutures for multiple locations both in vivo and in vitro, enabling biomedical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the preparation of biodegradable Mg@PLA / PCL triboelectric fibers (A), structure, and working mechanism (B);

[0027] Figure 2 Actual photos (A) and tensile strength (B) of Mg@PLA / PCL triboelectric fibers in Examples 2 and 4;

[0028] Figure 3 Degradation mechanism (A), parameters (B), and photos before and after degradation (C) of each component of Mg@PLA / PCL in Example 1.

[0029] Figure 4 Scanning electron microscopy (SEM) of the Mg@PLA fiber surface (A) and the Mg@PLA / PCL fiber cross section (B) in Example 2;

[0030] Figure 5 The voltage and current signals output by the Mg@PLA / PCL fiber at different frequencies in Example 2;

[0031] Figure 6 Actual image of Mg@PLA / PCL fiber used to light up LED in Example 2;

[0032] Figure 7 In Example 2, Mg@PLA / PCL fibers were used to suture the lower limb ligaments of rabbits. DETAILED DESCRIPTION

[0033] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content of the application, and these equivalent forms also fall within the scope defined by the appended claims.

[0034] Magnesium wire (purity > 99.9%, diameter 0.1-0.3mm) was purchased from Suzhou Jingjun New Material Technology Co., Ltd., PLA (model 6202D, molecular weight 371930) was purchased from Nature Works Corporation, USA, and PCL (model S26795, molecular weight 80000) was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0035] The mechanical properties of Mg@PLA / PCL fibers were tested according to GB / T 1040.5-2006, using an Instron 5969 electronic universal testing machine from Instron Corporation, USA, with a fiber length of 30mm and a tensile rate of 100mm / min. The electrical output performance was tested using a Keithley 6514A.

[0036] Example 1

[0037] As shown in Figure 1 The device includes a conjugate spinning part and a melt spinning part. The conjugate spinning part includes a winding roller and two jet orifices arranged on both sides of the winding roller. The two jet orifices are respectively provided with positive and negative high pressure. The melt spinning part includes a glass cavity, a heating ring is arranged outside the glass cavity in series, and a metal spinning needle is arranged at the outlet of the glass cavity. The conjugate spinning part and the melt spinning part are connected by the drawn fiber.

[0038] The drawn biodegradable conductive wire is arranged in the center of the winding roller. The biodegradable polymer spinning solution (PLA) is conjugate spun and twisted by the winding roller to the surface of the biodegradable conductive wire (magnesium wire). The biodegradable thermoplastic material (PCL) is loaded into the glass cavity and placed in the central melting of the heating ring. The electrical core layer enters from the upper end of the glass cavity, is drawn through the melted biodegradable thermoplastic material, is drawn out from the metal spinning needle at the bottom of the cavity, and is drawn to obtain a triboelectric fiber, as shown in Figure 3 Since the materials used all have biodegradability, a 3cm long fiber can be completely degraded in 11 weeks.

[0039] Example 2

[0040] (1) PLA was added to a hexafluoroisopropanol solution to obtain a PLA / hexafluoroisopropanol solution, wherein the mass fraction of PLA was 10%.

[0041] (2) Put 0.1 mm magnesium wire into the conjugate electrostatic spinning machine, and take the same volume of solution in step (1) into the syringe respectively to perform conjugate spinning, the positive and negative voltage is +12 kV and -12 kV respectively, the collection roller speed is 6 r / min, and the winding roller speed is 500 r / min, so as to obtain Mg@PLA core-sheath fiber with an average diameter of 150 um, and the surface morphology is as shown in Figure 4 A.

[0042] (3) Put PCL particles into a glass cavity, and heat the bottom end metal spinning needle with an inner diameter of 0.25 mm to PCL melting in the heating ring.

[0043] (4) Continue to stretch the fiber in step (2) into the melt in step (3), and then draw out from the bottom end needle, so as to obtain Mg@PLA / PCL composite fiber with an average diameter of 250 um, and the tensile strength can reach 48.9 MPa, and the cross-sectional morphology is as shown in Figure 4 B.

[0044] (5) The friction positive layer PLA and the friction negative layer PCL can generate the same frequency of alternating current signals by the contact-separation movement of a certain frequency under the action of bending or external force, so as to generate the output of electric energy.

[0045] As shown in Figure 1 B, it is the working mechanism diagram of the triboelectric fiber, and the energy collection process of the Mg@PLA / PCL fiber is as follows: under the action of external force, the fiber is deformed slightly in microcosm, the friction positive layer PLA contacts the friction negative layer PCL, and due to the difference in electronegativity, the electrons flow from the PLA layer to the PCL layer. When the external force is removed, the PLA layer and the PCL layer are separated, and due to the potential difference, the electrons flow from the ground to the magnesium electrode, generating an induced current. When the external force is applied again, the PLA and PCL layers gradually approach, the potential difference decreases, and the electrons flow from the magnesium electrode to the ground. In this way, the contact and separation are continuously carried out, the mechanical energy collected by the Mg@PLA / PCL triboelectric fiber is converted into the output of alternating current pulse signals, so as to output electric energy to the outside.

[0046] As shown in Figure 5 , the Mg@PLA / PCL composite fiber generates different alternating voltages and currents under the action of external force at 1 Hz, 2 Hz and 3 Hz frequencies respectively, can supply power to various small electronic products, and can also collect biomechanical energy from human body movement, thereby proving the great potential of the Mg@PLA / PCL composite fiber in energy collection. Figure 6As shown, Mg@PLA / PCL can directly connect in series and successfully light up 5 green LEDs, showing its value in energy supply. In addition, as biodegradable triboelectric fibers, due to their thin diameter, good biocompatibility and non-toxic properties, they can be used as biological surgical sutures, such as Figure 7 As shown, Mg@PLA / PCL composite fibers are used to suture the knee ligament of the lower limbs of rabbits, showing their application prospects in biomedicine.

[0047] Example 3

[0048] (1) Add PLA to a hexafluoroisopropanol solution to obtain a PLA / hexafluoroisopropanol solution with a PLA mass fraction of 12%.

[0049] (2) Stretch 0.1 mm magnesium wire into a conjugate electrospinning machine, and take the same volume of solution in step (1) into a syringe for conjugate spinning, with positive and negative voltages of +10 kV and -10 kV respectively, a collection roller speed of 3 r / min, and a winding roller speed of 500 r / min, to obtain Mg@PLA core-sheath fibers with an average diameter of 300 um.

[0050] (3) Put PCL particles into a glass cavity, with a metal spinning needle with an inner diameter of 0.45 mm at the bottom, and heat to PCL melting in the heating ring.

[0051] (4) Continue to stretch the fiber in step (2) into the melt in step (3), and then pull it out from the bottom needle to obtain Mg@PLA / PCL composite fibers with an average diameter of 450 um.

[0052] (5) The positively charged PLA layer and the negatively charged PCL layer will generate an alternating current signal of the same frequency through contact-separation motion at a frequency of 2 Hz, thereby generating an output of electrical energy.

[0053] As the PLA concentration increases, the collection roller speed and the spinning voltage decrease, the diameter of the electrospun PLA nanofiber and the thickness of the PLA layer increase, and the fiber gradually becomes hard, which to some extent reduces the charge transfer density, resulting in a decrease in output voltage and current.

[0054] Example 4

[0055] (1) Add PLA to a hexafluoroisopropanol solution to obtain a PLA / hexafluoroisopropanol solution with a PLA mass fraction of 15%.

[0056] (2) 0.3 mm magnesium wire was drawn into the conjugate electrospinning machine, and the same volume of solution in step (1) was taken into the syringe respectively to perform conjugate spinning. The positive and negative voltages were +9 kV and -9 kV respectively, the collection roller speed was 1.5 r / min, and the winding roller speed was 300 r / min. Mg@PLA core-sheath fiber with an average diameter of 450 um was obtained.

[0057] (3) PCL particles were placed in a glass cavity, and a metal spinning needle with an inner diameter of 0.6 mm at the bottom end was heated to PCL melting in the heating ring.

[0058] (4) Continue to draw the fiber in step (2) into the melt in step (3), and then pull it out from the bottom end needle. Mg@PLA / PCL composite fiber with an average diameter of 600 um was obtained, and the tensile strength could reach 284.5 MPa.

[0059] (5) The friction of the positive and negative layers of PLA and PCL under the action of bending or external force will generate an alternating current signal of the same frequency through contact-separation movement of 2 Hz frequency, thereby generating an output of electric energy.

[0060] The Mg electrode is thickened, the collection roller and winding roller speed are further reduced, the thickness of the PLA layer is increased, and the increase in the thickness of the PCL layer causes the fiber to become hard, resulting in a further reduction in output voltage and current. Therefore, by reasonably controlling the thickness between the layers, frictional electric fibers with different flexibility and output voltage and current can be obtained.

Claims

1. A triboelectric fiber, characterized by, The triboelectric fiber comprises a spiral electrical core layer and a skin layer; wherein the spiral electrical core layer comprises bioabsorbable conductive filaments and a biodegradable polymer dielectric fiber layer; and the skin layer is a biodegradable thermoplastic material. The bioabsorbable conductive filaments are magnesium filaments; the biodegradable polymer dielectric fiber is a polylactic acid (PLA) dielectric fiber; and the biodegradable thermoplastic material is polycaprolactone (PCL). The diameter of the bioabsorbable conductive filaments in the spiral electrical core layer is 100-300 um, the thickness of the biodegradable polymer dielectric fiber layer is 50-300 um, and the thickness of the skin layer is 50-300 um.

2. A preparation method of a triboelectric fiber, comprising: (1) performing conjugate spinning on a biodegradable polymer spinning solution and twisting the bioabsorbable conductive filaments on the surface by a winding roller to obtain an electrical core layer; (2) drawing the electrical core layer obtained in step (1) into a melt of a biodegradable thermoplastic material and drawing out to obtain a triboelectric fiber. In step (1), the bioabsorbable conductive filaments are magnesium filaments with a diameter of 100-300 um; the biodegradable polymer is polylactic acid (PLA) with a mass percentage concentration of 10%-15% in the spinning solution. In step (2), the biodegradable thermoplastic material is polycaprolactone (PCL). In step (2), the method specifically comprises: connecting heating rings in series as a melt cavity, loading the biodegradable thermoplastic material into the glass cavity and placing it in the central melt of the heating ring, and drawing the electrical core layer from the upper end and drawing it out from the metal spinning needle at the bottom of the cavity.

3. The preparation method according to claim 2, characterized in that: In step (1), the two-pole spinneret in the conjugate spinning is respectively provided with positive and negative high voltage, and the spinning solution becomes dielectric nanofibers under the action of electrostatic force; wherein the positive and negative high voltage ranges from +9 to +12 kV and from -9 to -12 kV, the speed of the winding roller is 300-500 r / min, and the speed of the collection roller is 1.5-6 r / min.

4. The preparation method according to claim 2, characterized in that The temperature of the heating ring is 90-150 ℃, the drawing speed is 8-10 r / min, and the inner diameter of the metal spinning needle is 250-600 um.

5. An apparatus for use in the method of claim 2, wherein The device comprises a conjugate spinning part and a melt spinning part; wherein the conjugate spinning part comprises a winding roller and a two-pole spinneret; and the melt spinning part comprises a glass cavity, the glass cavity is provided with heating rings connected in series outside, and the glass cavity outlet is provided with a metal spinning needle.

6. Application of the triboelectric fiber of claim 1 in small device energy supply or surgical sutures.

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