Preparation Method and Application of Highly Conductive and High-Strength PEDOT:PSS Fibers

Abstract

The present invention provides a method for preparing and applying highly conductive and high-strength PEDOT:PSS fibers. A spinning solution is obtained by blending an aqueous PEDOT:PSS solution and an ionic liquid, and a nascent fiber is formed in a coagulation bath. The nascent fiber is kept in an organic solvent vapor, annealed and washed, then soaked and stretched in a sulfuric acid solution, and finally washed and dried to obtain the highly conductive and high-strength PEDOT:PSS fibers. By adding the ionic liquid, the present invention promotes the phase separation of PEDOT and PSS, and under the thermal action of the organic solvent vapor, the phase separation migrates along the thermodynamic direction, improving the fiber structure orderliness. The organic solvent vapor causes the conformational change of the benzene-quinone conformation of PEDPT molecules, which is beneficial to carrier transport and also beneficial to removing the PSS phase during the soaking and stretching in concentrated sulfuric acid, improving the crystal orientation. The PEDOT:PSS fibers have good thermoelectric effects, high strength, simple preparation processes, and high industrial application value.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive fiber preparation, and particularly relates to a preparation method and application of highly conductive and high-strength PEDOT:PSS fibers. Background Art

[0002] In recent years, organic polymer conductive fibers have become a research hotspot of functional fibers. In particular, conductive fibers based on the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) have been widely used in fields such as flexible conductive materials due to their simple molecular structure, small energy gap, and high conductivity. However, PEDOT itself is an insoluble polymer, which limits its application as a conductive fiber. Currently, generally, water-soluble polymer electrolyte polystyrene sulfonic acid (PSS) is doped to solve the textile processing problem of PEDOT, and PEDOT:PSS conductive fibers are obtained, which have developed rapidly in the application field of flexible conductive devices.

[0003] In the prior art, the invention patent (application number: CN 202111360635.9) discloses a preparation method of high-strength and high-conductivity PEDOT fibers. First, a wet spinning solution is prepared, and then the spinning solution is injected into a concentrated sulfuric acid coagulation bath through a spinning pump for coagulation molding. Finally, the formed fibers are drawn out, and after washing and drying, PEDOT:PSS fibers with high strength and high conductivity are obtained. The invention patent (application number: CN 201810586502.5) discloses a preparation method of high-performance flexible PEDOT:PSS thermoelectric fibers. The prepared thermoelectric material is a P-type semiconductor material. By adding sulfuric acid to a commercial PEDOT:PSS aqueous solution dispersion, the mixed solution is sealed in a capillary tube. After constant temperature, the fibers are blown into absolute ethanol and then vacuum dried to obtain a high-performance flexible PEDOT:PSS thermoelectric fiber material. This preparation method is simple, low-cost, and the thermoelectric performance of the thermoelectric fibers is good.

[0004] However, in the above two methods for preparing PEDOT conductive fibers, directly placing the spinning solution in concentrated sulfuric acid for coagulation during the material preparation process, or directly adding sulfuric acid to intervene in the dispersion will affect the spinnability of the spinning solution, affect the fiber forming rate, and will also affect the strength of the prepared conductive fibers, making their mechanical properties unable to meet the application standards. Other measures need to be taken to make up for the loss of fiber strength caused by sulfuric acid, which increases the process steps and the preparation cost, and is not conducive to industrial production and preparation.

[0005] In view of this, it is necessary to design an improved preparation method and application of highly conductive and high-strength PEDOT:PSS fibers to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method and application of highly conductive and high-strength PEDOT:PSS fibers. By blending PEDOT:PSS with ionic liquids, the phase separation of PEDOT and PSS is promoted, and the nascent fibers are treated synergistically with organic solvent vapors. Under the action of heat, the phase separation migrates along the thermodynamic direction, improving the orderliness of the fiber structure. The organic solvent vapors also reduce the electrostatic binding force between PEDOT and PSS, facilitating the removal of the PSS phase by sulfuric acid soaking treatment. Stretching can improve the mechanical properties and conductivity of the fibers, obtaining highly conductive, high-strength, and flexible PEDOT:PSS fibers. This preparation method is suitable for batch production of PEDOT:PSS fibers in industry and has high popularization and application value.

[0007] To achieve the above object of the invention, the present invention provides a preparation method of conductive and high-strength PEDOT:PSS fibers, comprising the following steps:

[0008] S1. Prepare an aqueous solution of PEDOT:PSS, add a certain amount of ionic liquid, and obtain a spinning solution after ultrasonic treatment and magnetic stirring;

[0009] S2. After degassing the spinning solution obtained in step S1, extrude it through the spinneret holes of a spinning device into a coagulation bath for solidification molding, and obtain nascent fibers after drying treatment;

[0010] S3. Place the nascent fibers obtained in step S2 in a constant-temperature organic solvent vapor for a certain period of time, carry out annealing and washing, and then immerse them in a sulfuric acid solution for soaking-stretching treatment; finally, carry out washing bath treatment and drying treatment on the fibers to obtain highly conductive and high-strength PEDOT:PSS fibers.

[0011] As a further improvement of the present invention, in step S3, the organic solvent vapor includes one or more of N-methyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and ethylene glycol.

[0012] As a further improvement of the present invention, in step S3, the density of the organic solvent vapor is 0.05 - 0.2 ml / cm 3 , preferably 0.1 ml / cm 3 ; the temperature of the organic solvent vapor treatment is 120 - 150 °C, and the time is 10 - 120 min.

[0013] As a further improvement of the present invention, in step S1, the concentration of PEDOT:PSS in the aqueous solution of PEDOT:PSS is 1.3 wt% - 2.0 wt%.

[0014] As a further improvement of the present invention, the addition amount of the ionic liquid accounts for 4% - 10% of the total mass of PEDOT and PSS in the spinning solution.

[0015] As a further improvement of the present invention, in step S3, the mass percentage concentration of the sulfuric acid solution is 30% to 98%; the soaking time is 1 to 5 h, and the stretching ratio is 1 to 1.7 times.

[0016] As a further improvement of the present invention, in step S2, the spinning speed of the spinneret is 0.8 to 1.5 mL / h; the inner diameter of the spinneret is 0.15 to 0.4 mm; the coagulation bath is isopropyl alcohol.

[0017] As a further improvement of the present invention, the ionic liquid includes one or more of 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazole tricyanomethane, 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide, and 1-ethyl-3-methylimidazole hexafluorophosphate.

[0018] As a further improvement of the present invention, in step S3, the temperature of the annealing treatment is 100 to 140 °C, and the annealing time is 10 to 120 min; the washing bath includes one or more of acetone, ethanol, ether, and isopropyl alcohol.

[0019] As a further improvement of the present invention, in step S1, the time of the ultrasonic treatment is 30 to 60 min, the parameters of the magnetic stirring are 500 to 800 rad / min, and the time is 10 to 14 h; in step S2, the degassing treatment is to let the spinning solution stand at -0.1 Mpa for 5 to 30 min; in step S2 or step S3, the drying treatment is carried out at room temperature.

[0020] The present invention also provides an application of a highly conductive and high-strength PEDOT:PSS fiber. The PEDOT:PSS fiber is prepared by the preparation method described in any one of the above, and the application of the PEDOT:PSS fiber includes being used as a power source to supply power to a sensing device, and applications in the fields of smart clothing and wearable electronic devices.

[0021] The beneficial effects of the present invention are:

[0022] 1. A preparation method and application of a highly conductive and high-strength PEDOT:PSS fiber provided by the present invention. The method is to blend an aqueous PEDOT:PSS solution and an ionic liquid to obtain a spinning solution; defoam the spinning solution, and form it in a coagulation bath to obtain a nascent fiber; place the nascent fiber in a constant-temperature organic solvent vapor for a period of time, and then after annealing and washing, immerse it in a sulfuric acid solution for soaking-stretching treatment; finally, after washing bath and drying treatment, a highly conductive and high-strength PEDOT:PSS fiber is obtained. By blending PEDOT:PSS with an ionic liquid, the present invention can promote the phase separation of PEDOT and PSS, and use organic solvent vapor to treat the nascent fiber. Under the action of heat, this phase separation will migrate along the thermodynamic direction, improving the orderliness of the fiber structure. And the treatment with organic solvent vapor is beneficial to removing PSS by soaking and stretching in a sulfuric acid solution, improving the crystal orientation, and obtaining a PEDOT:PSS fiber with high conductivity, high strength and flexibility; this preparation method is suitable for batch production of PEDOT:PSS fibers in industry and has high popularization and application value.

[0023] 2. The present invention uses wet spinning. An ionic liquid is added to the spinning solution. The ionic liquid can promote the phase separation of PEDOT and PSS, and the treatment of the nascent fiber with organic solvent vapor can not only promote the phase separation effect of the ionic liquid on PEDOT and PSS, remove part of PSS, and this phase separation migrates along the thermodynamic direction under the thermal action of the organic solvent vapor, enabling the fiber molecules to re-assemble themselves, increasing the orientation of the fiber molecules, enhancing the conductivity and strength of the fiber; it can also cause the benzene-quinone conformation of the PEDPT molecule to change. The organic solvent vapor can enter the PEDOT:PSS fiber completely by capillary action, reducing the electrostatic interaction between PEDOT and PSS, promoting the transformation of the benzene-quinone conformation of PEDOT, and the transformation from the benzene conformation in a curly globular structure to the linear quinone conformation is beneficial to carrier transport, further enhancing the conductivity of the fiber. In addition, for the fiber treated with organic solvent vapor, the electrostatic binding force between PEDOT and PSS is weakened. During the soaking and stretching process in the sulfuric acid solution, the combination of H + and PSS - is strengthened, which is beneficial to the removal of the PSS phase in PEDOT:PSS and improves the conductivity; stretching during the soaking process will straighten the originally randomly distributed molecular chains, tending to be along the load-bearing direction of the fiber, obtaining a straight and ordered structure, which not only improves the mechanical properties of the fiber, but also enhances the carrier mobility and improves the conductivity; and the stretching treatment can also increase the contact area between sulfuric acid and the fiber, promoting the combination of H + and PSS - is beneficial to the removal of the PSS phase and further improves the conductivity of the fiber.

[0024] 3. By selecting a polar solvent as the organic solvent vapor, the present invention can weaken the Coulomb force between PEDOT and PSS, which is beneficial to the phase separation of PEDOT and PSS and the conformational change of PEDOT molecular chains from coiled to straight chains, thus facilitating the improvement of the fiber conductivity. By adjusting the density of the organic solvent vapor, the penetration force of the vapor on the nascent fiber is increased, enabling the organic solvent vapor to contact the fiber fully and uniformly. By regulating the temperature and time, the degree of orientation and the conformational change of benzene-quinone of the fiber molecules are ensured, and flexible PEDOT:PSS fibers with high conductivity and high strength are obtained.

[0025] 4. The present invention utilizes the synergistic cooperation of ionic liquid, organic solvent vapor treatment, and sulfuric acid solution soaking and stretching treatment to promote the conformational change of benzene-quinone of PEDOT, improve the conductivity of the fiber, cause phase separation between PEDOT and PSS, remove most of the PSS phase in PEDOT:PSS, further improve the conductivity, and also improve the crystal orientation of the fiber, obtaining a straight and ordered molecular structure, thereby improving the mechanical properties of the fiber. The PEDOT:PSS fiber has good thermoelectric effect and simple preparation process, providing the possibility for large-scale production of high-performance fibers; it has high popularization and application value in the fields of power supply for sensing devices, smart clothing, and wearable electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the electron microscope image of the highly conductive and high-strength PEDOT:PSS fiber prepared in Example 1 of the present invention.

[0027] Figure 2 It is the electron microscope image of the PEDOT:PSS fiber prepared in Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail below with reference to the drawings and specific embodiments.

[0029] Here, it should also be noted that in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0030] In addition, it should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article or device.

[0031] A preparation method of a conductive and high-strength PEDOT:PSS fiber, comprising the following steps:

[0032] S1. Prepare an aqueous PEDOT:PSS solution, add a certain amount of ionic liquid, and obtain a spinning solution after ultrasonic treatment and magnetic stirring; wherein, the ultrasonic treatment time is 30-60 min, and the parameters of magnetic stirring are 500-800 rad / min and the time is 10-14 h;

[0033] S2. After degassing the spinning solution in step S1, extrude it through the spinneret holes of a spinning device into an isopropanol coagulation bath for solidification and molding, and obtain a nascent fiber after drying treatment; wherein, the degassing treatment is to let the spinning solution stand at -0.1 Mpa for 5-30 min; the drying treatment is carried out at room temperature;

[0034] S3. Place the nascent fiber in step S2 in a constant-temperature organic solvent vapor for a period of time, then carry out annealing and washing treatments, and immerse it in a sulfuric acid solution for soaking-stretching treatment; finally, carry out a washing bath treatment on the fiber and dry it at room temperature to obtain a highly conductive and high-strength PEDOT:PSS fiber.

[0035] In particular, the present invention adopts wet spinning, and an ionic liquid is added to the spinning solution. The ionic liquid can promote the phase separation of PEDOT and PSS. The organic solvent vapor acts on the nascent fiber, which can not only promote the phase separation effect of the ionic liquid on PEDOT and PSS, remove part of PSS (polystyrene sulfonic acid), and this phase separation migrates along the thermodynamic direction under the thermal action of the organic solvent vapor, increasing the orientation of fiber molecules. At the same time, the high temperature provides energy for the movement of fiber molecules, enabling them to re-assemble, improving the orderliness of fiber molecules, and thereby enhancing the conductivity and mechanical strength of the fiber. The organic solvent vapor can also cause the benzene-quinone conformation of PEDPT (poly(3,4-ethylenedioxythiophene)) molecules to change. The organic solvent vapor can enter the PEDOT:PSS fiber completely by capillary action. By using its own small molecular structure, it reduces the electrostatic interaction between PEDOT and PSS, promotes the transformation of the benzene-quinone conformation of PEDOT, and the transformation from the benzene conformation in a curly cluster structure to the linear quinone conformation is beneficial to carrier transport, further enhancing the conductivity of the fiber.

[0036] For the fiber treated with organic solvent vapor, the electrostatic binding force between PEDOT and PSS is weakened. During the process of soaking and stretching in the sulfuric acid solution, the H + in the sulfuric acid and PSS -The combination is conducive to the removal of the PSS phase in PEDOT:PSS, improving the conductivity; stretching during the soaking process will straighten the originally randomly distributed molecular chains, tending to be along the load-bearing direction of the fiber, resulting in a straightened and ordered structure, which not only improves the mechanical properties of the fiber, but also enhances the carrier mobility and increases the conductivity; moreover, the stretching treatment can also increase the contact area between sulfuric acid and the fiber, promoting H + and PSS - The combination is conducive to the removal of the PSS phase and further improves the conductivity of the fiber.

[0037] Specifically, in step S3, the organic solvent vapor includes one or more of N-methyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and ethylene glycol. The density of the organic solvent vapor is 0.05 - 0.2 ml / cm 3 , preferably 0.1 ml / cm 3 kg / m 3 ; the temperature of the organic solvent vapor treatment is 120 - 150 °C, and the time is 10 - 120 min. By selecting an organic solvent as the organic solvent vapor, the Coulomb force between PEDOT and PSS can be weakened, which is conducive to the phase separation of PEDOT and PSS and the conformational change of PEDOT molecular chains from coiled to straight chains, and is conducive to the improvement of the fiber conductivity. By adjusting the density of the organic solvent vapor, the penetration force of the vapor on the as-spun fiber can be increased, so that the organic solvent vapor contacts the fiber fully and evenly. By adjusting the temperature and time, the degree of orientation and benzene-quinone conformational change of the fiber molecules is ensured, and a highly conductive and high-strength flexible PEDOT:PSS fiber is obtained. This PEDOT:PSS fiber has good thermoelectric effect, simple preparation process, and provides the possibility for large-scale production of high-performance fibers.

[0038] In step S1, the concentration of PEDOT:PSS in the PEDOT:PSS aqueous solution is 1.3 wt% - 2.0 wt%, and the mass ratio of PEDOT to PSS is 1:2.5. The addition amount of the ionic liquid in the spinning solution accounts for 4% - 10% of the total mass of PEDOT and PSS in the spinning solution. The addition of the ionic liquid can not only promote the phase separation of PEDOT and PSS in the fiber, but also increase the spinnability of the spinning solution, which is conducive to the preparation of PEDOT:PSS fibers and the formation of a uniform fiber structure.

[0039] In step S3, the mass percentage concentration of the sulfuric acid solution is 30% to 98%; the soaking time is 1 to 5 h, and the drawing ratio is 1 to 1.7 times. The size of the drawing ratio has an important influence on the crystal orientation degree of the fiber, and thus has an impact on both the mechanical properties and the conductivity of the fiber. Moreover, in the present invention, the as-solidified primary fiber is soaked in the sulfuric acid solution, which reduces the damage of sulfuric acid to the fiber strength and does not affect the spinnability of the spinning solution. In addition, the soaking and drawing treatment is carried out simultaneously, which improves the orientation of the fiber molecules in the load-bearing direction and improves the mechanical properties of the fiber.

[0040] In some specific embodiments, the ionic liquid includes one or more of 1-ethyl-3-methylimidazolium dicyanamide (EMIMDCA), 1-ethyl-3-methylimidazole tricyanomethane (EMIM TCM), 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide (EMIM TFSI), and 1-ethyl-3-methylimidazole hexafluorophosphate (EMIM PF6).

[0041] Specifically, in step S2, the spinning speed of the spinneret is 0.8 to 1.5 mL / h; the inner diameter of the spinneret is 0.15 to 0.4 mm; the coagulation bath is isopropyl alcohol. The present invention limits the spinning speed to adapt to the spinning performance of the spinning solution and avoid problems such as uneven fiber structure and poor spinning effect. The coagulation bath is isopropyl alcohol or acetone.

[0042] In step S3, the temperature of the annealing treatment is 100 to 140 °C, and the annealing time is 10 to 120 min; the annealing treatment is used to evaporate the excess organic solvent in the PEDOT:PSS fiber to avoid affecting the subsequent application of the conductive fiber.

[0043] In some specific embodiments, in step S3, the washing bath includes one or more of acetone, ethanol, ether, and isopropyl alcohol.

[0044] The present invention also provides an application of a highly conductive and high-strength PEDOT:PSS fiber. The PEDOT:PSS fiber is prepared by the above preparation method. The application of the PEDOT:PSS fiber includes powering a sensing device as a power source, applications in the fields of smart clothing and wearable electronic devices. The present invention utilizes the synergistic cooperation of ionic liquid, organic solvent vapor treatment, and sulfuric acid solution soaking and stretching treatment to promote the conformational transformation of the benzene-quinone conformation of PEDOT, improve the conductivity of the fiber, cause phase separation between PEDOT and PSS, remove most of the PSS phase in PEDOT:PSS, further improve the conductivity, and also improve the crystal orientation of the fiber to obtain a straight and ordered molecular structure, thereby improving the mechanical properties of the fiber.

[0045] Example 1

[0046] This embodiment provides a method for preparing highly conductive and high-strength PEDOT:PSS fibers, comprising the following steps:

[0047] S1. Prepare an aqueous PEDOT:PSS solution with a concentration of 1.5 wt% (the mass ratio of PEDOT to PSS is 1:2.5), add an ionic liquid EMIM DCA accounting for 5% of the total mass of PEDOT and PSS, and obtain a spinning solution after 40 min of ultrasonic treatment and magnetic stirring (600 rad / min for 12 h);

[0048] S2. Degas the spinning solution obtained in step S1, let it stand for 15 min at -0.1 Mpa, extrude it through the spinneret holes (inner diameter 0.3 mm, spinning speed 1 mL / h) of a spinning device into an isopropanol coagulation bath for solidification molding, and obtain primary fibers after drying at room temperature;

[0049] S3. Place the primary fibers obtained in step S2 in an organic solvent vapor (ethylene glycol) at 150 °C for 60 min, and the density of the organic solvent vapor is 0.08 ml / cm 3 ; Anneal the fibers at 120 °C for 50 min, wash them in an ethanol washing bath, then soak and stretch the fibers in a sulfuric acid solution with a concentration of 98% while soaking, where the soaking time is 2 h and the stretching ratio is 1.5 times; Finally, wash the fibers in an ethanol washing bath and dry them at room temperature to obtain highly conductive and high-strength PEDOT:PSS fibers.

[0050] Please refer to Figure 1 As shown, it is the electron micrograph of the highly conductive and high-strength PEDOT:PSS fibers prepared in Example 1. It can be seen from the figure that since ethylene glycol makes the molecular chains of the fibers unfold from a coiled conformation to a straight conformation, the surface of the fibers is relatively smooth and flat.

[0051] Example 2

[0052] This embodiment provides a method for preparing highly conductive and high-strength PEDOT:PSS fibers. Compared with Example 1, the difference lies in that the organic solvent vapor is dimethyl sulfoxide, and the rest is substantially the same as in Example 1, which will not be elaborated here.

[0053] Comparative Example 1

[0054] Comparative Example 1 provides a method for preparing PEDOT:PSS fibers. Compared with Example 1, the difference lies in that the primary fibers are not treated with an organic solvent vapor, and the rest is substantially the same as in Example 1, which will not be elaborated here.

[0055] Please refer to Figure 2As shown, it is the electron microscope image of the PEDOT:PSS fiber prepared in Comparative Example 1. It can be seen from the figure that for the fiber structure without being treated with organic solvent vapor, the orientation of fiber molecules is poor, the degree of conformational transformation of PEDOT from benzene-quinone is poor, and the surface is rougher.

[0056] Comparative Example 2

[0057] Comparative Example 2 provides a method for preparing PEDOT:PSS fiber. Compared with Example 1, the difference lies in that water vapor is used to replace organic solvent vapor to treat the nascent fiber, and the rest is substantially the same as that in Example 1, which will not be elaborated here.

[0058] Comparative Example 3

[0059] Comparative Example 3 provides a method for preparing PEDOT:PSS fiber. Compared with Example 1, the difference lies in that no ionic liquid is added to the spinning solution, and the rest is substantially the same as that in Example 1, which will not be elaborated here.

[0060] Comparative Example 4

[0061] Comparative Example 4 provides a method for preparing PEDOT:PSS fiber. Compared with Example 1, the difference lies in that the soaking and stretching treatments with sulfuric acid solution are not carried out in step S3, and the rest is substantially the same as that in Example 1, which will not be elaborated here.

[0062] Comparative Example 5

[0063] Comparative Example 5 provides a method for preparing PEDOT:PSS fiber. Compared with Example 1, the difference lies in that the nascent fiber is soaked in sulfuric acid solution in step S3, but the stretching treatment is not carried out, and the rest is substantially the same as that in Example 1, which will not be elaborated here.

[0064] Comparative Example 6

[0065] Comparative Example 6 provides a method for preparing PEDOT:PSS fiber. Compared with Example 1, the difference lies in that the nascent fiber is not treated with organic solvent vapor, sulfuric acid is directly used as the coagulation bath and stretching is not carried out, and the rest is substantially the same as that in Example 1, which will not be elaborated here.

[0066] The PEDOT:PSS fibers prepared in Examples 1-2 and Comparative Examples 1-6 were tested for electrical conductivity and mechanical properties, and the results are shown in the following table.

[0067] Table 1 Properties of PEDOT:PSS fibers prepared in Examples 1-2 and Comparative Examples 1-6

[0068] Conductivity (S / cm) Seebeck coefficient (μV / K) Tensile strength (MPa) Example 1 3888 14.9 584 Example 2 3679 15.3 584 Comparative Example 1 2433 14.4 433 Comparative Example 2 2398 14.2 444 Comparative Example 3 3463 8.7 449 Comparative Example 4 455 14.7 432 Comparative Example 5 1477 14.9 442 Comparative Example 6 1211 14.7 431

[0069] As can be seen from Table 1, by comparing Example 1 with Comparative Example 3, it can be known that the addition of ionic liquid increases the Seebeck coefficient of the fiber. According to the comparison between Example 1 and Comparative Examples 1-2, after being treated with organic solvents, both the electrical conductivity and mechanical properties of the fiber are significantly improved, and ethylene glycol is the best organic solvent for steam treatment. By comparing Example 1 with Comparative Examples 4-5, soaking in sulfuric acid and stretching treatment greatly enhance the electrical conductivity and mechanical strength of the fiber. Using sulfuric acid directly as the coagulation bath causes certain damage to the strength of the fiber. Thus, it can be seen that the synergistic combination of ionic liquid, organic solvent steam treatment, and sulfuric acid solution soaking and stretching treatment improves the electrical conductivity and mechanical properties of the fiber.

[0070] Examples 3-4

[0071] Examples 3-4 provide a method for preparing highly conductive and high-strength PEDOT:PSS fibers. Compared with Example 1, the differences are that the density, temperature, time of the organic solvent steam, and the addition amount of ionic liquid in the spinning solution are as shown in the following table, and the rest are roughly the same as those in Example 1, so they will not be elaborated here.

[0072] Comparative Examples 7-14

[0073] Comparative Examples 7-14 provide a method for preparing highly conductive and high-strength PEDOT:PSS fibers. Compared with Example 3, the differences are that the density, temperature, time of the organic solvent steam, and the addition amount of ionic liquid in the spinning solution are as shown in the following table, and the rest are roughly the same as those in Example 3, so they will not be elaborated here.

[0074] Table 2 Parameter settings of PEDOT:PSS fibers prepared in Examples 3-4 and Comparative Examples 7-14

[0075] <![CDATA[Density (kg / m 3 )]]> Temperature (°C) Time (min) Addition amount (%) Example 3 0.1 150 60 5 Example 4 0.1 150 60 8 Comparative Example 7 0.01 150 60 5 Comparative Example 8 0.4 150 60 5 Comparative Example 9 0.1 100 60 5 Comparative Example 10 0.1 200 60 5 Comparative Example 11 0.1 150 5 5 Comparative Example 12 0.1 150 150 5 Comparative Example 13 0.1 150 60 2 Comparative Example 14 0.1 150 60 15

[0076] Comparative Example 15

[0077] Comparative Example 15 provides a method for preparing highly conductive and high-strength PEDOT:PSS fibers. Compared with Example 3, the difference is that in step S3, the stretching multiple is 2 times, and the rest are roughly the same as those in Example 3, so they will not be elaborated here.

[0078] Example 5

[0079] Example 5 provides a method for preparing highly conductive and high-strength PEDOT:PSS fibers. Compared with Example 3, the difference is that in step S3, the soaking time is 5h, and the rest are roughly the same as those in Example 3, so they will not be elaborated here.

[0080] Comparative Example 16

[0081] Comparative Example 16 provides a method for preparing highly conductive and high-strength PEDOT:PSS fibers. Compared with Example 3, the difference lies in that in step S3, the soaking time is 6 h, and the rest is substantially the same as in Example 3, which will not be elaborated here.

[0082] The PEDOT:PSS fibers prepared in Examples 3 to 5 and Comparative Examples 7 to 16 were tested for electrical conductivity and mechanical properties, and the results are shown in the following table.

[0083] Table 3 Properties of PEDOT:PSS fibers prepared in Examples 3 to 5 and Comparative Examples 7 to 16

[0084] Conductivity (S / cm) Seebeck coefficient (μV / K) Tensile strength (MPa) Example 3 4231 14.9 584 Example 4 4107 14.1 578 Example 5 4187 14.8 412 Comparative Example 7 2998 15.3 489 Comparative Example 8 3665 15.1 451 Comparative Example 9 3873 15.2 412 Comparative Example 10 4191 14.8 574 Comparative Example 11 3716 15.0 446 Comparative Example 12 4203 14.5 586 Comparative Example 13 3889 13.4 447 Comparative Example 14 3217 13.8 487 Comparative Example 15 4078 14.8 334 Comparative Example 16 4210 14.5 453

[0085] As can be seen from Table 3, in Examples 3 and Comparative Examples 7 to 8, as the density of the organic solvent vapor increases, the penetration force of the vapor on the nascent fibers increases, and the conductivity and strength increase, but further increase will instead cause the conductivity and strength to decrease. In Examples 3 and Comparative Examples 9 to 10, the increase in the treatment temperature will affect the improvement of fiber properties, but after reaching a certain temperature, the fiber properties tend to be stable and it is difficult to have a large improvement; similarly, the treatment time also shows the same pattern. Therefore, the treatment temperature and time are limited from the perspectives of cost saving and preparation efficiency improvement. Comparing Examples and Comparative Examples 13 to 14, it can be seen that too much addition of ionic liquid will cause the fiber volume to increase, the conductivity to decrease, and there is no significant improvement in the Seebeck coefficient; while if the addition amount of ionic liquid is insufficient, the Seebeck coefficient is difficult to improve; and too much or too little ionic liquid is not conducive to the strength of the fiber. In the comparison of Examples 3 and 5 and Comparative Example 16, too long sulfuric acid treatment time will not significantly increase the conductivity and will reduce the mechanical properties of the fiber. Comparing Example 3 with Comparative Example 15, it can be seen that too high a draw ratio will have an adverse effect on the structure of the fiber and will instead result in a loss of fiber strength.

[0086] In summary, the present invention provides a method for preparing and applying highly conductive and high-strength PEDOT:PSS fibers. The preparation method involves blending an aqueous PEDOT:PSS solution and an ionic liquid to obtain a spinning solution; degassing the spinning solution, shaping it in a coagulation bath to obtain nascent fibers; placing the nascent fibers in a constant-temperature organic solvent vapor for a period of time, annealing and washing them, and then immersing them in a sulfuric acid solution for soaking-stretching treatment; and finally, obtaining highly conductive and high-strength PEDOT:PSS fibers after drying treatment. The present invention utilizes the blending of PEDOT:PSS and an ionic liquid to promote the phase separation of PEDOT and PSS, and uses organic solvent vapor to treat the nascent fibers. Under the action of heat, this phase separation migrates along the thermodynamic direction, improving the orderliness of the fiber structure; the organic solvent vapor can also cause a conformational change of the benzene-quinone conformation of the PEDPT molecule, which is beneficial to carrier transport, further enhancing the electrical conductivity of the fiber and improving the fiber conductivity. In addition, for the fibers treated with organic solvent vapor, the electrostatic binding force between PEDOT and PSS is weakened. During the soaking and stretching process in the sulfuric acid solution, the binding of H + with PSS - is strengthened, which is beneficial to the removal of the PSS phase in PEDOT:PSS; stretching not only improves the mechanical properties of the fiber, but also enhances the carrier mobility and conductivity; and the stretching treatment can also increase the contact area between sulfuric acid and the fiber, which is beneficial to the removal of the PSS phase and further improves the electrical conductivity of the fiber. The present invention utilizes the synergistic cooperation of ionic liquid treatment, organic solvent vapor treatment, and sulfuric acid solution soaking-stretching treatment to promote the conformational change of the benzene-quinone conformation of PEDOT, improve the conductivity of the fiber, cause phase separation between PEDOT and PSS, remove most of the PSS phase in PEDOT:PSS, further improve the electrical conductivity, and also improve the crystal orientation of the fiber, obtaining a straight and ordered molecular structure, thereby improving the mechanical properties of the fiber; the PEDOT:PSS fiber has good thermoelectric effect, simple preparation process, provides the possibility for large-scale production of high-performance fibers, and has high industrial application value.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of highly conductive and high-strength PEDOT:PSS fibers, characterized in that, it comprises the following steps: S1. Prepare an aqueous PEDOT:PSS solution, add a certain amount of ionic liquid, and obtain a spinning solution after ultrasonic treatment and magnetic stirring; S2. After degassing the spinning solution obtained in step S1, extrude it through the spinneret holes of a spinning device into a coagulation bath for solidification and molding, and obtain primary fibers after drying treatment; S3. Place the primary fibers obtained in step S2 in a constant-temperature organic solvent vapor for a certain period of time, perform annealing and washing, and then immerse them in a sulfuric acid solution for soaking-stretching treatment; finally, perform a washing bath treatment and a drying treatment on the fibers to obtain highly conductive and high-strength PEDOT:PSS fibers; In step S3, the density of the organic solvent vapor is 0.05 to 0.2 ml / cm 3 ; the temperature of the organic solvent vapor treatment is 120 to 150 °C, and the time is 10 to 120 min.

2. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, in step S3, the organic solvent vapor includes one or more of N-methyl-2-pyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and ethylene glycol.

3. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, The density of the organic solvent vapor is 0.1 ml / cm 3 .

4. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, in step S1, the concentration of PEDOT:PSS in the aqueous PEDOT:PSS solution is 1.3 wt% to 2.0 wt%; the addition amount of the ionic liquid accounts for 4% to 10% of the total mass of PEDOT and PSS in the spinning solution.

5. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, in step S3, the mass percentage concentration of the sulfuric acid solution is 30% to 98%; the soaking time is 1 to 5 h, and the stretching ratio is 1 to 1.7 times.

6. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, in step S2, the spinning speed of the spinneret holes is 0.8 to 1.5 mL / h; the inner diameter of the spinneret holes is 0.15 to 0.4 mm; the coagulation bath is isopropyl alcohol.

7. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, the ionic liquid includes one or more of 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazole tricyanomethane, 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide, and 1-ethyl-3-methylimidazole hexafluorophosphate.

8. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, in step S3, the annealing treatment temperature is 100 to 140 °C, and the annealing time is 10 to 120 min; the washing bath includes one or more of acetone, ethanol, ether, and isopropyl alcohol.

9. The preparation method of highly conductive and high-strength PEDOT:PSS fibers according to claim 1, characterized in that, In step S1, the time of the ultrasonic treatment is 30 to 60 min, the parameters of the magnetic stirring are 500 to 800 rad / min, and the time is 10 to 14 h; in step S2, the defoaming treatment is to let the spinning solution stand at -0.1 Mpa for 5 to 30 min; in step S2 or step S3, the drying treatment is carried out at room temperature.

10. Application of a highly conductive and high-strength PEDOT:PSS fiber, characterized in that, the PEDOT:PSS fiber is prepared by the preparation method described in any one of claims 1 to 9, and the application of the PEDOT:PSS fiber includes applications in the fields of powering a sensing device as a power source, smart clothing, and wearable electronic devices.

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