A composite nanofiber / gel composite material, a preparation method and application thereof

Abstract

The application provides a composite nanofiber / gel composite material, and belongs to the technical field of polymer materials.The composite nanofiber / gel composite material provided by the application comprises an ionic gel, the ionic gel comprises an organic polymer and a salt electrolyte, and is characterized in that the composite nanofiber dispersed in the ionic gel is further included, the composite nanofiber is composed of a polymer nanofiber and a nanorod, and one end of the nanorod is embedded in the polymer nanofiber.The composite nanofiber / gel composite material provided by the application has excellent mechanical stability and ion transmission capacity, and can be used to solve the problem of poor mechanical property stability of a traditional ionic hydrogel ion skin.Moreover, when the composite nanofiber / gel composite material is used in an ion skin, the sensing recession of the ion skin can be reduced, the sensing capacity of the ion skin can be improved, the applicability of the ion skin is improved, and the sensing capacity and the wide applicability are high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a composite nanofiber / gel composite material and a preparation method and application thereof. BACKGROUND

[0002] Intelligent wearable technology is a new type of electronic manufacturing process that combines traditional clothing with electronic manufacturing technology, and can be widely applied in the fields of intelligent sensing, flexible robots or motion monitoring. Ion skin is a functional composite material composed of ion channels, fiber skeletons, fiber modification materials and other components, and has a flexible and elastic function. It is the core element of the new generation of intelligent wearable devices, and determines the application performance of the final intelligent wearable device.

[0003] Current ion skin is mainly divided into hydrogel or hydrogel composite system. Hydrogel as the main structure of ion skin has excellent ion conduction capacity, and is one of the most potential types of intelligent wearable devices. Chinese patent CN201811277536.2 discloses a preparation of a new type of double network hydrogel and application of the obtained double network hydrogel. The obtained sodium alginate-polyacrylamide double network hydrogel has excellent properties such as strength, toughness, softness, elasticity and fatigue resistance, but the highest fracture toughness is only 4.77 MJ / m3. Chinese patent CN202110455284.3 discloses a preparation method and application of a double network polyvinyl alcohol-polyacrylic acid hydrogel. By using double network polyvinyl alcohol-polyacrylic acid, the strength and toughness of the gel are improved, but the highest strength can only be increased to 1 MPa. Chinese patent CN202210984162.8 discloses a high-tensile self-healing universal adhesive elastomer hydrogel material and a preparation method thereof. By means of reversible covalent bond interaction between borax and -OH groups, non-covalent bond interaction such as hydrophobic stacking of casein molecular micelles and hydrogen bond interaction between polymer molecular chains, a multifunctional elastomer hydrogel with high tensile property and high fatigue resistance is constructed, but its tensile toughness can only reach 5.98 MJ / m 3 It can be seen that although there are many studies on ion skin hydrogel, the strength and toughness of the currently disclosed hydrogel ion skin are still low, and the mechanical stability is poor, which seriously reduces the sensing performance and sensitivity of the ion skin during use. SUMMARY

[0004] The purpose of the present application is to provide a composite nanofiber / gel composite material with good mechanical stability and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0006] The present application provides a composite nanofiber / gel composite material, comprising an ionic gel, the ionic gel comprising an organic polymer and a salt electrolyte, characterized in that further comprising composite nanofibers dispersed in the ionic gel, the composite nanofibers consisting of a polymer nanofiber and a nanorod, one end of the nanorod being embedded in the polymer nanofiber.

[0007] Preferably, the organic polymer in the ionic gel comprises one or more of polyacrylamide, polyvinyl alcohol and agar.

[0008] Preferably, the material of the polymer nanofiber comprises one or more of polyoxymethylene dicyandiamide, polycaprolactam, thermoplastic polyurethane, polyethylene terephthalate alcohol, polyacrylonitrile and polydimethylsiloxane.

[0009] Preferably, characterized in that the diameter of the polymer nanofiber is 100-1500 nm.

[0010] Preferably, the nanorod comprises one or more of TiO2 nanorod, SiO2 nanorod, Ag nanorod, carbon nanotube and cellulose whisker.

[0011] Preferably, the diameter of the nanorod is 2-30 nm, and the length of the nanorod is 100-600 nm.

[0012] Preferably, the mass ratio of the polymer nanofiber, nanorod and ionic gel is (0.5-1.5):(0.008-0.05):(120-160).

[0013] The present application also provides a preparation method of the composite nanofiber / gel composite material described in the above technical solution, comprising the following steps:

[0014] (1) preparing the composite nanofiber by airflow coaxial spinning, fiber surface modification or blending spinning;

[0015] The airflow coaxial spinning comprises the following steps: spinning the polymer solution as the core layer spinning solution, spinning the nanorod dispersion liquid as the skin layer spinning solution, coaxially spinning the core layer spinning solution and the skin layer spinning solution, and drying the formed fiber to obtain the composite nanofiber;

[0016] The fiber surface modification comprises the following steps: spinning the polymer solution by airflow spinning to obtain the polymer nanofiber, immersing the polymer nanofiber in the nanorod dispersion liquid, and sequentially performing immersion modification and drying to obtain the composite nanofiber;

[0017] The blending spinning comprises the following steps: mixing the polymer, the nanorod and the solvent to obtain a mixed slurry; performing air-jet spinning on the mixed slurry, and drying the fiber obtained by the air-jet spinning to obtain the composite nanofiber.

[0018] (2) mixing the composite nanofiber obtained in the step (1) with a hydrogel precursor, a crosslinking agent and a metal ion salt, performing a crosslinking reaction to obtain a composite nanofiber / gel composite material.

[0019] Preferably, the crosslinking agent comprises tetramethylethylenediamine, sodium sulfate or calcium chloride.

[0020] The application further provides an application of the composite nanofiber / gel composite material in an ion skin.

[0021] The application provides a composite nanofiber / gel composite material, comprising an ionic gel, the ionic gel comprising an organic polymer and a salt electrolyte, characterized in that the composite nanofiber dispersed in the ionic gel, the composite nanofiber consisting of a polymer nanofiber and a nanorod, one end of the nanorod being embedded in the polymer nanofiber. In the application, the ionic gel has ion transmission capacity, and can make the composite nanofiber / gel composite material have ion transmission capacity. In the application, the organic polymer serves as a gel skeleton of the ionic gel. In the application, the polymer fiber has the characteristics of high strength and high elongation, and can serve as a supporting skeleton of the ionic gel and improve the mechanical properties of the ionic gel as a reinforcing body. Meanwhile, since the composite nanofiber consists of the polymer nanofiber and the nanorod, one end of the nanorod being embedded in the polymer nanofiber, this structure can improve the interfacial bonding force between the composite nanofiber and the ionic gel and further improve the mechanical properties of the ionic gel on the one hand, and the polymer nanofiber and the nanorod can constitute an ion channel and improve the ion transmission capacity of the ion channel on the other hand. Moreover, the diameter of the polymer nanofiber is not less than the diameter of the nanorod, which can ensure that the polymer nanofiber is still a continuous fiber structure after being embedded by the nanorod, and further can form a continuous network structure after the composite nanofiber is dispersed in the ionic gel, thereby ensuring the mechanical properties of the composite nanofiber / gel composite material. The results of the examples show that the crack propagation resistance of the composite nanofiber / gel composite material provided by the application can reach 2000 times, and the tensile fracture can reach 56 MJ / m 3, the modulus can reach 55 MPa. It can be seen that the composite nanofiber / gel composite material provided by the application has excellent mechanical stability and ion transmission capacity, and can be used to solve the problem of poor mechanical property stability of the traditional ion gel ion skin. Moreover, since the composite nanofiber / gel composite material provided by the application has excellent ion transmission capacity, when it is used in the ion skin, the sensing recession of the ion skin can be reduced, the sensing capacity of the ion skin can be improved, the applicability of the ion skin is improved, and high sensing capacity and wide applicability are shown. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 SEM image of the composite nanofiber prepared for Example 1 of the application;

[0023] Figure 2 Schematic diagram of the composite nanofiber / gel composite material prepared for Example 1 of the application;

[0024] Figure 3 Schematic diagram of the composite nanofiber / gel composite material prepared for Example 2 of the application;

[0025] Figure 4 Schematic diagram of the composite nanofiber / gel composite material prepared for Example 3 of the application;

[0026] Figure 5 Schematic diagram of the hydrogel ion skin prepared for Comparative Example 1 of the application. DETAILED DESCRIPTION

[0027] The application provides a composite nanofiber / gel composite material, which comprises an ion gel, the ion gel comprising an organic polymer and a salt electrolyte, and is characterized by further comprising a composite nanofiber dispersed in the ion gel, the composite nanofiber being composed of a polymer nanofiber and a nanorod, one end of the nanorod being embedded in the polymer nanofiber.

[0028] In the application, unless otherwise specified, the reagents used in the application are commercially available products well known to those skilled in the art.

[0029] The composite nanofiber / gel composite material provided by the application comprises an ion gel, the ion gel comprising an organic polymer and a salt electrolyte.

[0030] In the application, the ion gel has ion transmission capacity, which enables the composite nanofiber / gel composite material to have ion transmission capacity, and further enables the composite nanofiber / gel composite material to be used in an ion skin.

[0031] In the present application, the organic polymer in the ionic gel preferably comprises one or more of polyacrylamide, polyvinyl alcohol and agar. In the present application, when the ionic gel is the above-mentioned substance, it has a good ion transmission capacity.

[0032] In the present application, the salt electrolyte preferably comprises a salt containing Li ions, Ca ions or Na ions, and more preferably comprises LiCl, CaCl2 or NaCl. In the present application, when the salt electrolyte is the above-mentioned type, it has excellent conductivity in the hydrogel, thereby improving the conductivity of the ionic gel.

[0033] In the present application, the composite nanofiber is composed of a polymer nanofiber and a nanorod, and one end of the nanorod is embedded in the high-polymer nanofiber.

[0034] In the present application, the embedding of one end of the nanorod in the high-polymer nanofiber enables the nanorod to be firmly combined with the polymer nanofiber, and the dispersion of the composite nanofiber in the ionic gel can improve the mechanical properties of the ionic gel on one hand, and the polymer nanofiber and the nanorod can form an ion channel, thereby improving the ion transmission capacity and ion transmission rate of the ion channel. In the present application, it can be ensured that the polymer nanofiber still has a continuous fiber structure after being embedded by the nanorod.

[0035] In the present application, the depth of embedding of the nanorod in the polymer nanofiber is not particularly limited, and the nanorod can be inserted into the polymer nanofiber.

[0036] In the present application, the number of nanorods on the surface of the polymer nanofiber is not particularly limited, and it can be adjusted according to the diameters of the polymer nanofiber and the nanorod, and the mass ratio of the polymer nanofiber, the nanorod and the ionic gel.

[0037] In the present application, the material of the polymer nanofiber preferably comprises one or more of polyoxymethylene, polycaprolactam, thermoplastic polyurethane, polyethylene terephthalate alcohol, polyacrylonitrile and polydimethylsiloxane, and more preferably is thermoplastic polyurethane or polyoxymethylene. In the present application, when the material of the polymer nanofiber is the above-mentioned type, on one hand, the polymer nanofiber formed by the above-mentioned polymer is more conducive to the embedding of the nanorod in the polymer nanofiber to form a composite nanofiber; on the other hand, the formed polymer nanofiber has good mechanical properties, which is conducive to improving the mechanical properties of the ionic gel.

[0038] In the present application, the diameter of the polymer nanofiber is preferably 100-1500 nm, more preferably 500-1000 nm. When the diameter of the polymer nanofiber is within the above range, it is more advantageous to disperse in the ionic gel. The length of the polymer nanofiber is not particularly limited in the present application, and can be selected as needed.

[0039] In the present application, the nanorod preferably includes one or more of TiO2 nanorod, SiO2 nanorod, Ag nanorod, carbon nanotube, and cellulose whisker. When the nanorod is of the above type, it has high mechanical strength, and embedding it in the high polymer nanofiber can improve the mechanical properties of the composite nanofiber.

[0040] In the present application, the diameter of the nanorod is preferably 2-30 nm, more preferably 10-20 nm, and the length of the nanorod is preferably 100-600 nm, more preferably 200-500 nm. When the diameter and length of the nanorod are within the above range, it is more advantageous to embed in the polymer nanofiber.

[0041] In the present application, the mass ratio of the polymer nanofiber, nanorod, and ionic gel is preferably (0.5-1.5):(0.008-0.05):(120-160), more preferably (0.8-1.5):(0.008-0.03):(120-160), and further preferably (0.8-1.2):(0.01-0.02):(120-160). When the mass ratio of the polymer nanofiber, nanorod, and ionic gel is within the above range, it is more advantageous to embed a sufficient amount of nanorod on the surface of the polymer nanofiber, and further improve the ion transport rate of the composite nanofiber / gel composite material.

[0042] The composite nanofiber / gel composite material provided in the present application improves the ion skin properties of the conventional hydrogel by embedding nanorods on the surface of the fiber as a reinforcing body, enhances the interfacial bonding of the composite nanofiber and ionic gel, and improves the mechanical stability and ion transport rate of the composite nanofiber / gel composite material.

[0043] The present application also provides a preparation method of a composite nanofiber / gel composite material, comprising the following steps:

[0044] (1) preparing a composite nanofiber by airflow coaxial spinning, fiber surface modification, or blending spinning;

[0045] The air flow coaxial spinning includes the following steps: taking a polymer solution as a core layer spinning solution, taking a nanorod dispersion solution as a skin layer spinning solution, coaxially spinning the core layer spinning solution and the skin layer spinning solution, drying the formed fiber, and obtaining the composite nanofiber.

[0046] The fiber surface modification includes the following steps: air flow spinning a polymer solution to obtain a polymer nanofiber, immersing the polymer nanofiber in a nanorod dispersion solution, and sequentially performing immersion modification and drying to obtain the composite nanofiber.

[0047] The blending spinning includes the following steps: mixing a polymer, a nanorod and a solvent to obtain a mixed slurry; air flow spinning the mixed slurry, and drying the fiber obtained by the air flow spinning to obtain the composite nanofiber.

[0048] (2) mixing the composite nanofiber obtained in the step (1) with a hydrogel precursor, a crosslinking agent and a metal ion salt, performing a crosslinking reaction, and obtaining a composite nanofiber / gel composite material.

[0049] In the present application, the polymer used in the air flow coaxial spinning, the fiber surface modification or the blending spinning for preparing the composite nanofiber is of the same material as the polymer used for preparing the composite nanofiber / gel composite material in the above technical solution; the nanorod used in the air flow coaxial spinning, the fiber surface modification or the blending spinning for preparing the composite nanofiber is the same as the nanorod of the composite nanofiber / gel composite material in the above technical solution; and no further description is given here.

[0050] The present application adopts the air flow coaxial spinning, the fiber surface modification or the blending spinning to prepare the composite nanofiber.

[0051] In the present application, the air flow coaxial spinning includes the following steps: taking a polymer solution as a core layer spinning solution, taking a nanorod dispersion solution as a skin layer spinning solution, coaxially spinning the core layer spinning solution and the skin layer spinning solution, drying the formed fiber, and obtaining the composite nanofiber.

[0052] In the present application, the concentration of the polymer solution is preferably 12-20 wt.%, more preferably 15-18 wt.%. In the present application, the concentration of the nanorod dispersion solution is preferably 0.15-0.4 wt.%, more preferably 0.2-0.3 wt.%. In the present application, when the concentrations of the polymer solution and the nanorod dispersion solution are in the above ranges, it is more beneficial to form continuous fibers during air flow spinning, and the mass ratio of the polymer nanofiber to the nanorod in the formed composite nanofiber is preferably (0.8-1.5):(0.008-0.03), more preferably (0.8-1.2):(0.01-0.02).

[0053] The solvent used in the polymer solution is not particularly limited in the present application, and any solvent capable of dissolving the polymer can be used. In the present application, the solvent used in the polymer solution preferably includes one or more of glycerol, n-butanol, ethylene glycol, isopropyl alcohol, tetrahydrofuran, and dimethylformamide, more preferably one or more of acetone, tetrahydrofuran, dimethylformamide, and ethanol, further preferably a mixture of tetrahydrofuran and dimethylformamide, and the volume ratio of tetrahydrofuran to dimethylformamide in the mixture is preferably (3-7):(3-7), more preferably 1:1. In the present application, dimethylformamide is helpful for dissolving the polymer, but it has poor volatility, and by adding tetrahydrofuran which has high volatility, the evaporation of the solvent during the spinning process can be facilitated, and the fiber-forming ability can be improved.

[0054] The solvent used in the nanorod dispersion liquid is not particularly limited in the present application, and any solvent capable of dispersing the nanorod can be used. In the present application, the solvent used in the nanorod dispersion liquid preferably includes one or more of acetone, tetrahydrofuran, dimethylformamide, and ethanol.

[0055] In the present application, the nanorod dispersion liquid further preferably includes a dispersant. The dispersant can facilitate the dispersion of the nanorod in the solvent, and after the electrospinning, the nanorod can be uniformly dispersed on the surface of the polymer nanofiber. In the present application, the dispersant preferably includes one or more of sodium dodecyl sulfate (SDS), polyvinylpyrrolidone, sodium citrate, polyvinyl alcohol, glycerol, or sodium polyacrylate. The amount of the dispersant used in the present application is not particularly limited, and it can be adjusted as needed. In the present application, the mass ratio of the nanorod to the dispersant is preferably (1-1.5):(10-15). When the mass ratio of the nanorod to the dispersant is within the above range in the present application, the nanorod can be sufficiently dispersed.

[0056] In the present application, the needle used in the coaxial spinning is preferably 15G for the sheath layer and 22G for the core layer. The extrusion speed of the core layer of the coaxial spinning is preferably 3-6 mL / h, more preferably 5 mL / h. The extrusion speed of the sheath layer of the coaxial spinning is preferably 0.5-2 mL / h, more preferably 1 mL / h. The distance from the spinneret to the receiving plate is preferably 40-70 cm, more preferably 50 cm. In the present application, the diameter of the polymer nanofiber is limited by the size of the needle. When the needle used in the coaxial spinning is of the above type, the diameter of the polymer nanofiber is 100-1200 nm. In the process of the coaxial spinning, the core layer and the sheath layer are set to different extrusion speeds. Under the drawing action of the electrospinning coaxial needle, the core layer spinning solution and the sheath layer spinning solution are ejected from the spinneret, and the ejected core layer spinning solution and sheath layer spinning solution are mixed at the contact part, so that part of the nanorod is mixed into the polymer solution. The solvent evaporates between the spinneret and the receiving plate to form a fiber, and as the solvent evaporates, the nanorod is embedded in the polymer nanofiber.

[0057] After the coaxial spinning is completed, the present application dries the fiber formed by the coaxial spinning to obtain the composite nanofiber. In the present application, the fiber formed by the coaxial spinning includes the solvent, and the excess solvent in the composite nanofiber can be removed by drying, and the polymer nanofiber shrinks to make the nanorod tightly embedded in the polymer nanofiber.

[0058] In the present application, the temperature of the drying is preferably 40-70°C, and more preferably 50°C; and the time of the drying is preferably 0.3-2h, and more preferably 1h. In the present application, when the temperature and the time of the drying are in the above ranges, the solvent in the fiber formed by the coaxial spinning can be sufficiently dried.

[0059] After the fiber formed by the coaxial spinning is dried, the present application preferably washes and dries the fiber obtained after the drying to obtain the composite nanofiber.

[0060] In the present application, the washing and the drying can remove the residual solvent and the dispersant in the composite nanofiber. The present application does not have special limitation on the operation method of the washing and the drying, and the operation method well known to those skilled in the art can be used. In the present application, the reagent of the washing is preferably deionized water, and the temperature of the drying is preferably 40-70°C, and more preferably 50°C. The present application does not have special limitation on the time of the drying, and the water in the composite nanofiber can be sufficiently removed.

[0061] In the present application, the surface modification of the fiber includes the following steps: air-jet spinning the polymer solution to obtain the polymer nanofiber, immersing the polymer nanofiber in the nanorod dispersion liquid, and sequentially performing the immersion modification and the drying to obtain the composite nanofiber.

[0062] The present application air-jet spins the polymer solution to obtain the polymer nanofiber.

[0063] In the present application, the concentration of the polymer solution is preferably 12-20wt.%, and more preferably 15-18wt.%. In the present application, when the concentration of the polymer solution is in the above range, it is more favorable for the air-jet spinning to form the continuous fiber.

[0064] The solvent used in the polymer solution is not particularly limited in the present application, and can be any solvent capable of dissolving the polymer. In the present application, the solvent used in the polymer solution preferably includes one or more of acetone, tetrahydrofuran, dimethylformamide and ethanol, and more preferably a mixture of tetrahydrofuran and dimethylformamide, wherein the volume ratio of tetrahydrofuran to dimethylformamide is preferably (3-7) : (3-7), and more preferably 1 : 1. In the present application, dimethylformamide is helpful for dissolving the polymer, but has poor volatility, and the addition of highly volatile tetrahydrofuran can help the solvent to volatilize during the spinning process, thereby improving the fiber-forming ability.

[0065] In the present application, the parameters for the electrospinning of the polymer solution preferably include the use of an 18G needle, and the voltage of the high-voltage power supply is preferably 18-32 KV, and more preferably 27 KV; the syringe extrusion speed is preferably 1-2.5 mL / h, and more preferably 1.5 mL / h; and the distance from the spinneret to the receiving plate is preferably 10-18 cm, and more preferably 15 cm. In the present application, when the parameters for the electrospinning are within the above ranges, the diameter of the polymer nanofiber can be 100-1200 nm, and it is more advantageous to form continuous polymer fibers.

[0066] After the electrospinning of the polymer solution is completed, the polymer nanofiber is immersed in the nanorod dispersion liquid in the present application, and then subjected to immersion modification and drying, thereby obtaining a composite nanofiber.

[0067] In the present application, the concentration of the nanorod dispersion liquid is preferably 0.1-0.4 wt.%, and more preferably 0.2-0.3 wt.%. In the present application, when the concentration of the nanorod dispersion liquid is within the above ranges, it is more advantageous to embed an appropriate amount of nanorods on the polymer nanofiber. In the present application, the mass ratio of the polymer nanofiber to the nanorod in the composite nanofiber is preferably (0.8-1.5) : (0.008-0.03), and more preferably (0.8-1.2) : (0.01-0.02).

[0068] In the present application, the nanorod dispersion liquid further preferably includes a dispersant which can promote the dispersion of the nanorod in the solvent and can make the nanorod uniformly disperse on the surface of the polymer nanofiber after the electrospinning. In the present application, the dispersant preferably includes one or more of sodium dodecyl sulfonate, polyvinylpyrrolidone, sodium citrate, polyvinyl alcohol, glycerol, or sodium polyacrylate. The present application does not have a special limitation on the amount of the dispersant, which can be adjusted as needed. In the present application, the mass ratio of the nanorod to the dispersant is preferably (1-1.2):(10-15). In the present application, when the mass ratio of the nanorod to the dispersant is in the above range, the nanorod can be sufficiently dispersed. The present application does not have a special limitation on the solvent used in the nanorod dispersion liquid, which can disperse the nanorod. In the present application, the solvent used in the nanorod dispersion liquid preferably includes ethanol or acetone.

[0069] In the present application, the polymer nanofiber obtained by electrospinning the polymer solution is preferably directly immersed in the nanorod dispersion liquid without drying. In the present application, since the polymer nanofiber obtained by electrospinning the polymer solution has not been dried, the surface of the polymer nanofiber is relatively soft, and it is more advantageous for the nanorod to be embedded after the polymer nanofiber is immersed in the nanorod dispersion liquid, thereby shortening the time for the immersion modification.

[0070] In the present application, the immersion modification is preferably performed under ultrasonic oscillation. In the present application, the ultrasonic oscillation can generate a cavitation effect during the process, and the tips of some nanorods can be embedded in the polymer nanofiber under the action of the cavitation effect. In the present application, the power of the ultrasonic oscillation is preferably 200-500 W, and the time of the ultrasonic oscillation is preferably 1-2 h, more preferably 1.5 h. In the present application, when the power and the time of the ultrasonic oscillation are in the above ranges, it is more advantageous for the nanorod to be embedded in the polymer nanofiber.

[0071] In the present application, the temperature of the drying is preferably 40-70°C, more preferably 50°C, and the time of the drying is preferably 0.3-2 h, more preferably 1 h. In the present application, when the temperature and the time of the drying are in the above ranges, the solvent in the fiber after the immersion modification can be dried.

[0072] After the immersion modification and the drying are completed, the present application preferably washes and dries the fiber obtained after the drying to obtain a composite nanofiber.

[0073] In the present application, the washing and drying can remove the residual solvent and dispersant in the fiber after the impregnation modification and drying. The method for the washing and drying is not particularly limited in the present application, and a method known to those skilled in the art can be used. In the present application, the washing agent is preferably deionized water, and the drying temperature is preferably 40-70°C, more preferably 50°C. The drying time is not particularly limited in the present application, and the water in the composite nanofiber can be sufficiently removed.

[0074] In the present application, the blending and spinning includes the following steps: mixing the polymer, nanorod and solvent to obtain a mixed slurry; performing air-jet spinning on the mixed slurry, and drying the fiber obtained by the air-jet spinning to obtain a composite nanofiber. In the present application, the mixed slurry of the polymer, nanorod and solvent is subjected to air-jet spinning, and the solvent volatilizes during the formation of the fiber by air-jet spinning and the drying process. With the volatilization of the solvent, the polymer fiber shrinks, and the nanorod is partially embedded in the polymer fiber.

[0075] The method for mixing the polymer, nanorod and solvent is not particularly limited in the present application, and a mixing method known to those skilled in the art can be used, and the above components can be sufficiently mixed. In the present application, the method for mixing the polymer, nanorod and solvent preferably includes dispersing the nanorod in the solvent under ultrasonic waves to obtain a nanorod dispersion, and then adding the polymer to the nanorod dispersion and stirring until the polymer is dissolved.

[0076] In the present application, the polymer, nanorod and solvent are further preferably mixed with a dispersant. The dispersant can promote the dispersion of the nanorod in the solvent, and can make the nanorod uniformly dispersed on the surface of the polymer nanofiber after air-jet spinning. In the present application, the dispersant preferably includes one or more of sodium dodecyl sulfonate, polyvinylpyrrolidone, sodium citrate, polyvinyl alcohol, glycerol or sodium polyacrylate. The amount of the dispersant is not particularly limited in the present application, and can be adjusted as needed. In the present application, the mass ratio of the nanorod to the dispersant is preferably 1:(200-500). When the mass ratio of the nanorod to the dispersant is in the above range, the nanorod can be sufficiently dispersed.

[0077] The solvent is not particularly limited in the present application, and can dissolve the polymer and disperse the nanorods. In the present application, the solvent preferably comprises one or more of acetone, tetrahydrofuran, dimethylformamide and ethanol, and more preferably a mixture of tetrahydrofuran and dimethylformamide, wherein the volume ratio of tetrahydrofuran to dimethylformamide is preferably (3-7):(3-7), and more preferably 1:1. In the present application, dimethylformamide helps to dissolve the polymer and disperse the nanorods, but has poor volatility. By adding tetrahydrofuran with high volatility, the solvent can be volatilized during the spinning process, and the fiber-forming ability can be improved.

[0078] In the present application, the mass content of the nanorods in the mixed slurry is preferably 0.5-2 wt.%, and more preferably 1-1.5 wt.%; and the mass content of the polymer in the mixed slurry is preferably 10-15 wt.%, and more preferably 12-15 wt.%. In the present application, when the mass contents of the nanorods and the polymer in the mixed slurry are within the above ranges, continuous composite nanofibers can be formed, and the mass ratio of the polymer nanofiber to the nanorods in the composite nanofiber is preferably (0.8-1.2):(0.01-0.02).

[0079] After obtaining the mixed slurry, the mixed slurry is subjected to electrospinning, and the fibers obtained by the electrospinning are dried to obtain the composite nanofiber.

[0080] In the present application, the parameters for the electrospinning of the mixed slurry preferably include: using an 18G needle, and the voltage of the high-voltage power supply is preferably 20-22 KV, and more preferably 20 KV; the jet extrusion speed is preferably 1.5-5 mL / h, and more preferably 3 mL / h; the distance from the jet to the receiving plate is preferably 10-15 cm, and more preferably 12 cm; and the spinning roller rotation speed is preferably 150-300 r / min, and more preferably 200 r / min. In the present application, when the parameters for the electrospinning are within the above ranges, the diameter of the polymer nanofiber can be 100-1200 nm, and it is more advantageous to form continuous composite nanofibers.

[0081] After the electrospinning of the mixed slurry, the fibers obtained by the electrospinning are preferably washed and dried to obtain the composite nanofiber.

[0082] In the present application, the washing and drying can remove the residual solvent and dispersant in the fibers after the electrospinning and drying. The operation method for the washing and drying is not particularly limited in the present application, and any operation method known to those skilled in the art can be used. In the present application, the washing agent is preferably deionized water, and the drying temperature is preferably 40-70°C, and more preferably 50°C. The drying time is not particularly limited in the present application, and the water in the composite nanofiber can be sufficiently removed.

[0083] The present application can make the composite nanofiber consist of polymer nanofiber and nanorod, one end of the nanorod is embedded in the high polymer nanofiber by adopting airflow coaxial spinning, fiber surface modification or blending spinning to prepare the composite nanofiber.

[0084] After obtaining the composite nanofiber, the present application mixes the composite nanofiber with hydrogel precursor, crosslinking agent and metal ion salt, carries out crosslinking reaction to obtain composite nanofiber / gel composite material.

[0085] In the present application, the mass ratio of the composite nanofiber and hydrogel precursor is preferably (0.8-1.5):(120-160), more preferably (0.8-1.2):(120-160). In the present application, when the mass ratio of the composite nanofiber and hydrogel precursor is in the above range respectively, the composite nanofiber can form abundant network structure in ionic gel, which can improve the mechanical stability of the composite nanofiber / gel composite material.

[0086] In the present application, the type of the crosslinking agent is adjusted according to the type of the hydrogel precursor. In the present application, when the hydrogel is polyvinyl alcohol, the crosslinking agent preferably includes sodium sulfate; when the hydrogel is agar, the crosslinking agent preferably includes calcium chloride.

[0087] In the present application, the mass ratio of the hydrogel precursor and crosslinking agent is preferably (35-45):(0.01-0.02), more preferably (40-45):(0.015-0.02). In the present application, when the mass ratio of the hydrogel precursor and crosslinking agent is in the above range, the hydrogel precursor is fully crosslinked to form hydrogel.

[0088] In the present application, the metal ion salt preferably includes LiCl, CaCl2 or NaCl. In the present application, the metal ion salt provides ionic component for the hydrogel, so that the hydrogel forms ionic gel. In the present application, the mass ratio of the hydrogel precursor and metal ion salt is preferably (15-20):(1-1.1), more preferably 17:1. In the present application, when the mass ratio of the hydrogel precursor and metal ion salt is in the above range, it is beneficial to make the ionic gel have better conductivity.

[0089] The present application does not have special limitation on the preparation method of the hydrogel precursor, and the preparation method of the hydrogel precursor known to those skilled in the art can be adopted.

[0090] The present application preferably mixes acrylamide, acrylic acid and initiator, carries out polymerization reaction to obtain colloid.

[0091] In the present application, the initiator preferably includes potassium persulfate. In the present application, the initiator is capable of initiating radical polymerization of acrylamide and acrylic acid to form a gel.

[0092] In the present application, the substance amount ratio of acrylamide, acrylic acid and initiator is preferably (400-900):(2-6):(1-2), more preferably (600-700):(2-4):(1-1.5). In the present application, acrylamide and acrylic acid provide monomers for ionic gel, and the substance amount ratio of acrylamide, acrylic acid and initiator in the above range enables sufficient reaction of acrylamide and acrylic acid.

[0093] After obtaining the gel, the present application preferably performs washing and drying on the gel to obtain a hydrogel precursor.

[0094] In the present application, the washing and drying are capable of removing solvent and impurities in the gel. The present application does not have special limitation on the operation method of the washing and drying, and a method well known to those skilled in the art can be used. In the present application, the washing reagent is preferably deionized water, and the drying is preferably freeze drying. In the present application, the freeze drying is capable of removing water in the hydrogel precursor without destroying the structure of the hydrogel precursor. In the present application, the temperature of the freeze drying is preferably -20 to -40℃, and the time of the freeze drying is preferably 5 to 8 h.

[0095] The present application does not have special limitation on the operation method of mixing the composite nanofiber with the hydrogel precursor, the crosslinking agent and the metal ion salt, and the above components can be mixed uniformly. In the present application, the mixing of the composite nanofiber with the hydrogel precursor, the crosslinking agent and the metal ion salt is preferably performed in the presence of a solvent with stirring. In the present application, the solvent is capable of promoting uniform mixing of the above components. The present application does not have special limitation on the type of the solvent, and a solvent well known to those skilled in the art can be used. In the present application, the solvent is preferably water.

[0096] In the present application, when the composite nanofiber is mixed with the hydrogel precursor, the crosslinking agent and the metal ion salt in the presence of a solvent. In the present application, the solvent enables sufficient mixing of the composite nanofiber with the hydrogel precursor, the crosslinking agent and the metal ion salt.

[0097] The present application preferably removes the solvent from the system obtained after mixing the composite nanofiber with the hydrogel precursor, the crosslinking agent and the metal ion salt, and then performs crosslinking reaction. In the present application, the method of removing the solvent is preferably vacuum degassing. In the present application, the vacuum degassing is capable of promoting removal of the solvent from the system.

[0098] In the present application, the temperature of the cross-linking reaction is preferably (70-95) °C, more preferably 90 °C; the time of the cross-linking reaction is preferably 30-70 min, more preferably 40 min. In the present application, when the temperature and time of the cross-linking reaction are in the above ranges, the hydrogel precursor can be cross-linked to form a hydrogel, and in the process of cross-linking, the metal ions and the composite nanofiber are uniformly distributed in the hydrogel to form a composite nanofiber / gel composite material.

[0099] The preparation method provided by the present application first prepares composite nanofibers by airflow coaxial spinning, fiber surface modification or blending spinning. The composite nanofibers prepared by this method are composed of polymer nanofibers and nanorods, and one end of the nanorod is embedded in the high polymer nanofiber. By controlling the diameter of the nanorod and the parameters of airflow spinning, the diameter of the polymer nanofiber can be not less than the diameter of the nanorod, which is conducive to the formation of a continuous network structure of the composite nanofiber in the ionogel.

[0100] The present application also provides the use of the composite nanofiber / gel composite material as an ion skin. The composite nanofiber / gel composite material provided by the present application has excellent mechanical stability and electrical conductivity, which can solve the problem of poor mechanical stability of the hydrogel ion skin in the prior art.

[0101] The application method of the composite nanofiber / gel composite material as an ion skin is not particularly limited in the present application, and the application method of the composite material as an ion skin known to those skilled in the art can be used. In the present application, after the preparation of the composite nanofiber / gel composite material is completed, it can be used as an ion skin by cutting according to needs.

[0102] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0103] Example 1

[0104] The preparation method of the composite nanofiber / gel composite material is as follows:

[0105] (1) Composite nanofibers are prepared by airflow coaxial spinning:

[0106] The polymer (thermoplastic polyurethane) is placed in a 20 mL volume ratio of 1:1 mixture solution of tetrahydrofuran and dimethylformamide, stirred at room temperature for 10-12 h using a magnetic stirrer to obtain the core layer spinning solution; the concentration of the polymer in the core layer spinning solution is 20 wt.%.

[0107] The nanorods (cellulose whiskers) and the dispersant (SDS) are dispersed in acetone to form the skin layer spinning solution, wherein the concentration of the nanorods in the skin layer spinning solution is 0.3%.

[0108] The syringe is used to extract the spinning solution for air-jet spinning, and the parameters of the air-jet spinning are as follows: the skin layer needle is 15G, the core layer needle is 22G, the core layer extrusion speed is 5 mL / h, the skin layer extrusion speed is 1 mL / h, and the distance from the spinning nozzle to the receiving plate is 50 cm.

[0109] The fibers are collected on the receiving plate, dried at 50℃ for 1 h to obtain the composite nanofibers, and the mass ratio of the polymer nanofibers to the nanorods in the composite nanofibers is 0.8:0.02.

[0110] (2) The composite nanofibers prepared in step (1) are mixed with a hydrogel precursor, a crosslinking agent (tetramethyl ethylenediamine), a metal ion salt (LiCl) and water to form a uniform dispersion liquid, which is poured into a mold, vacuum degassed, and then placed in an oven for heating at 90℃ for 40 min for crosslinking reaction to obtain a composite nanofiber / gel composite material; wherein the mass ratio of the composite nanofibers to the hydrogel precursor is 0.8:160; the mass ratio of the hydrogel precursor to the crosslinking agent is 35:0.02; and the mass ratio of the hydrogel precursor to the metal ion salt is 17:1.

[0111] The preparation method of the hydrogel precursor is as follows: acrylamide (AAm), acrylic acid (AA) and initiator potassium persulfate are subjected to a free radical polymerization reaction at 70℃ for 3 h to obtain a colloid, i.e. poly(acrylamide-acrylic acid) copolymer P(AAm-co-AA). The colloid is washed with deionized water to remove impurities. Then, the solvent is removed by freeze-drying to obtain a white powder. The molar ratio of acrylamide, acrylic acid and potassium persulfate is 500:2:1;

[0112] In the composite nanofiber / gel composite material prepared by the method, the diameter of the polymer nanofiber is 800-1500 nm, the diameter of the nanorod is 5-20 nm, the length of the nanorod is 300-600 nm, and the mass ratio of the polymer nanofiber, the nanorod and the ionic gel is 0.8:0.01:120.

[0113] The composite nanofibers prepared in the embodiment are tested by using an electron scanning electron microscope, and the SEM image is as shown in Figure 1as shown.

[0114] A schematic diagram of the composite nanofiber / gel composite material prepared in this example is shown in Figure 2 Figure 2 In the figure, 1 is cellulose nanowhisker, 2 is thermoplastic polyurethane (TPU) fiber, and 3 is polyacrylamide hydrogel.

[0115] Example 2

[0116] (1) Preparation of composite nanofiber by surface modification of fibers:

[0117] The polymer (thermoplastic polyurethane) is placed in a 20 mL mixed solution of tetrahydrofuran and dimethylformamide at a volume ratio of 1:1, stirred at room temperature using a magnetic stirrer for 10-12 h to obtain a polymer solution with a concentration preferably of 15 wt.%, and the spinning solution is extracted using a syringe to prepare polymer nanofibers using an air-jet spinning device; wherein the parameters of air-jet spinning are: an 18G needle is used, the voltage of the high-voltage power supply is 27 KV; the extrusion speed of the syringe is 1.5 mL / h; and the distance from the jet to the receiving plate is 15 cm.

[0118] An ethanol dispersion of nanorods (cellulose whiskers) with a concentration of 0.2 wt.% is prepared, and a dispersant SDS is added to the dispersion, wherein the mass ratio of nanorods to dispersant is 1:10.

[0119] The prepared polymer nanofibers are directly added to the ethanol dispersion of nanorods, ultrasonically shaken for 1 h, the fibers are taken out, washed with deionized water, and dried at 50°C for 1 h to obtain composite nanofibers, and the mass ratio of polymer nanofibers to nanorods in the formed composite nanofibers is 0.8:0.016.

[0120] (2) Same as step (2) of Example 1.

[0121] In the composite nanofiber / gel composite material prepared by this method, the diameter of the polymer nanofiber is 1500 nm, the diameter of the nanorod is 10 nm, the length of the nanorod is 400 nm, and the mass ratio of the polymer nanofiber, the nanorod, and the ionogel is 1.2:0.01:140.

[0122] A schematic diagram of the composite nanofiber / gel composite material prepared in this example is shown in Figure 3

[0123] Example 3

[0124] (1) Preparation of composite nanofiber by blending spinning:

[0125] ​​The polymer, nanorod and solvent are mixed to obtain a mixed slurry; the mixed slurry is subjected to air-jet spinning, and the fiber obtained by the air-jet spinning is dried to obtain the composite nanofiber. The specific method is as follows: 20 mL of a mixed solution of nanorods (cellulose whiskers) in a volume ratio of 1:1 of tetrahydrofuran and dimethylformamide is ultrasonically treated for 20 min at room temperature, and then the polymer (thermoplastic polyurethane) is added to the above solution and stirred on a magnetic stirrer for 10 h, followed by ultrasonic treatment for 1 h to obtain a mixed slurry; wherein the mass content of the nanorod in the mixed slurry is 2 wt.%, and the mass content of the polymer in the mixed slurry is 14 wt.%.

[0126] The obtained mixed slurry is subjected to air-jet spinning, then washed with deionized water and dried at 50℃ to obtain the composite nanofiber, and the mass ratio of the polymer nanofiber to the nanorod in the composite nanofiber is 1.0:0.015.

[0127] The parameters of the air-jet spinning are as follows: an 18G needle is used, the voltage of the high-voltage power supply is 20KV, the jet extrusion speed is 3 mL / h, the distance from the jet nozzle to the receiving plate is 12 cm, and the spinning roller rotation speed is 200 r / min.

[0128] (2) The same as step (2) of Example 1.

[0129] The diameter of the polymer nanofiber in the composite nanofiber / gel composite material prepared by the method is 1500 nm, the diameter of the nanorod is 10 nm, the length of the nanorod is 400 nm, and the mass ratio of the polymer nanofiber, the nanorod and the ion gel is 0.08:0.1:160.

[0130] The schematic diagram of the composite nanofiber / gel composite material prepared in the example is shown in Figure 4 .

[0131] Comparative Example 1

[0132] A traditional ion skin and a preparation method thereof, comprising the following steps:

[0133] (1) 4 g of polyacrylamide master batch, 2 g of LiCl, 30 mL of deionized water, stirring for 20 min, adding 0.003 g of ammonium persulfate, 0.007 g of methylene bisacrylamide, 15 μL of tetramethyl ethylenediamine, and fully stirring to obtain a hydrogel precursor;

[0134] (2) Pour the hydrogel precursor into a mold, place the mold into a 90℃ oven for curing, and obtain a hydrogel ion skin after 50 min.

[0135] The schematic diagram of the hydrogel ion skin prepared in the comparative example is shown in Figure 5 .

[0136] Test Example

[0137] 1. Modulus: Stretch test was performed on the ionic skin using a tensile tester, and the modulus was obtained from the engineering software.

[0138] 2. Sensitivity coefficient: The water gel was stretched by 50% deformation using a tensile tester, and the resistance change of the measurement sensor was measured using a multimeter. The sensitivity coefficient was obtained by processing the obtained data. The greater the sensitivity coefficient, the better the performance of the sensor.

[0139] 3. Crack propagation resistance: A notch was added to the middle of the prepared ionic skin sample, and it was subjected to 100% deformation cyclic stretching. The number of times the ionic skin stretched to break was recorded. The more the number of cyclic stretching times, the better the sensor's resistance to crack propagation.

[0140] 4. Stretch breaking energy: The ionic skin was stretched until it broke, and the stress-strain curve was integrated. The area of the curve was the stretch breaking energy.

[0141] The composite nanofiber / gel composite material obtained in Examples 1-3 and the water gel ionic skin prepared in Comparative Example 1 were tested for performance, including modulus, sensing sensitivity, crack propagation resistance, and breaking strength, using the above methods, respectively. The test results are shown in Table 1:

[0142] Table 1 Performance test results of the composite materials prepared in Examples 1-3 and Comparative Example 1

[0143] Sample name Modulus Sensitivity factor Crack growth resistance Tensile energy to break Example 1 25 MPa 10.5 2000 times 39 MJ / m 3 ]] Example 2 55 MPa 12.4 1500 times 56 MJ / m 3 ]] Example 3 32 MPa 5.7 1200 times 27 MJ / m 3 ]] Comparative Example 1 0.8 MPa 1.15 80 times 13 MJ / m 3 ]]

[0144] From the above experimental data, it can be seen that the composite nanofiber in the composite nanofiber / gel composite material provided by the present application is a fiber material modified by nanorods, which is stably dispersed in the ionic gel as a reinforcing body. The tight nanoscale rod structure can effectively increase the bonding ability of the fiber and the gel, and can be used as a reinforcing body to improve the mechanical properties and bending resistance of the ionic gel. In addition, the composite nanofiber can construct ion channels along the fiber, improving the conductivity of the composite material and greatly improving its sensitivity. Therefore, the composite nanofiber / gel composite material provided by the present application has excellent mechanical stability and ion transport ability, and can be used for ionic skin.

[0145] The composite nanofiber / gel composite material prepared by the preparation method provided by the present application has excellent mechanical stability and ion transport ability, and can be used for ionic skin. The preparation process is simple, safe and environmentally friendly, and can be stored for a long time. It is easy to realize large-scale production, and the prepared composite material has high sensitivity and stable mechanical properties. The prepared composite material can be used for ionic skin, and can be widely used in the manufacture of intelligent wearable devices.

[0146] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A composite nanofiber / gel composite material comprising an ionic gel, the ionic gel comprising an organic polymer and a salt electrolyte, characterized in that, Further comprising composite nanofibers dispersed in the ionic gel, the composite nanofibers being composed of polymer nanofibers and nanorods, one end of the nanorods being embedded in the polymer nanofibers; The organic polymer in the ionic gel comprises polyacrylamide; The material of the polymer nanofibers comprises one or more of polyoxymethylene dicylanide, polycaprolactam, thermoplastic polyurethane, polyethylene terephthalate alcohol, polyacrylonitrile and polydimethylsiloxane; The diameter of the polymer nanofibers is 100-1500 nm; The nanorods are cellulose whiskers; The diameter of the nanorods is 2-30 nm, and the length of the nanorods is 100-600 nm.

2. The composite nanofiber / gel composite of claim 1, wherein The mass ratio of the polymer nanofibers, nanorods and ionic gel is (0.5-1.5):(0.008-0.05):(120-160).

3. A preparation method of the composite nanofiber / gel composite material according to any one of claims 1-2, comprising the following steps: (1) preparing composite nanofibers by airflow coaxial spinning, fiber surface modification or blending spinning; The airflow coaxial spinning comprises the following steps: spinning a polymer solution as a core layer spinning solution, spinning a nanorod dispersion solution as a skin layer spinning solution, coaxially spinning the core layer spinning solution and the skin layer spinning solution, and drying the formed fibers to obtain composite nanofibers; The fiber surface modification comprises the following steps: airflow spinning a polymer solution to obtain polymer nanofibers, immersing the polymer nanofibers in a nanorod dispersion solution, and sequentially performing immersion modification and drying to obtain composite nanofibers; The blending spinning comprises the following steps: mixing a polymer, nanorods and a solvent to obtain a mixed slurry; airflow spinning the mixed slurry, and drying the fibers obtained by the airflow spinning to obtain composite nanofibers; The material of the polymer nanofibers comprises one or more of polyoxymethylene dicylanide, polycaprolactam, thermoplastic polyurethane, polyethylene terephthalate alcohol, polyacrylonitrile and polydimethylsiloxane; The diameter of the polymer nanofibers is 100-1500 nm; The nanorods are cellulose whiskers; The diameter of the nanorods is 2-30 nm, and the length of the nanorods is 100-600 nm. (2) mixing the composite nanofibers obtained in step (1) with a hydrogel precursor, a crosslinking agent and a metal ion salt, performing a crosslinking reaction to obtain a composite nanofiber / gel composite material; The hydrogel precursor is a poly(acrylamide-acrylic acid) copolymer; The crosslinking agent is tetramethyl ethylenediamine.

4. Application of the composite nanofiber / gel composite material according to any one of claims 1-2 or prepared by the preparation method of claim 3 as an ionic skin.

Images