Amphiphilic carbon fiber as well as preparation method and application thereof

Abstract

The invention relates to the technical field of carbon fiber surface modification, and discloses an amphiphilic carbon fiber and a preparation method thereof.The amphiphilic carbon fiber comprises a carbon fiber matrix, a hydrophilic functional group and a hydrophobic functional group, and the hydrophilic functional group and the hydrophobic functional group are modified on the surface of the carbon fiber matrix; the hydrophilic functional group is selected from one or more of an amino-substituted ionic liquid group, hydroxyl and carboxyl. The ionic liquid is electrochemically grafted, and the amphiphilic carbon fiber is formed by utilizing ion exchange reaction, so that the reaction efficiency can be effectively improved. The obtained amphiphilic carbon fiber and resin have good binding capacity, the water dispersion performance is improved, the performance expression of the carbon fiber is improved, and the application range is widened.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber surface modification, and in particular to an amphiphilic carbon fiber and a preparation method thereof. Background Art

[0002] As a high-performance fiber, carbon fiber has the characteristics of high strength, high modulus, good thermal stability and corrosion resistance. In the application process of carbon fiber, its interface bonding ability is one of the important factors affecting its use. Conventional carbon fiber has fewer surface active functional groups and is difficult to combine well with the matrix resin, and its performance cannot be effectively expressed. It is also hydrophobic and difficult to disperse in water or polar solvents, which limits the expansion of its application field.

[0003] This shortcoming can be compensated by surface modification, such as sizing the carbon fiber to adapt to different resins and enhance hydrophilicity. However, there is a problem that special sizing agents have narrow applications, and conventional sizing agents have shortcomings in performance. Therefore, research on enhancing the universality of carbon fibers is also gradually being carried out. Amphiphilic carbon fibers can interact with hydrophilic and hydrophobic groups, which can effectively improve the surface binding ability of carbon fibers. However, the current methods such as oxidation-chemical grafting have a relatively complicated reaction process and also require heating energy measures, which is not conducive to industrial production. A simpler modification method is urgently needed, and the current carbon fiber has poor comprehensive performance of interface shear strength and poor water dispersion. Therefore, it is urgent to study a modified carbon fiber with better comprehensive performance of interface shear strength and better water dispersion. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of poor comprehensive performance of carbon fiber interface shear strength and poor water dispersion performance in the prior art, and to provide an amphiphilic carbon fiber and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides an amphiphilic carbon fiber, wherein the amphiphilic carbon fiber includes a carbon fiber matrix and hydrophilic functional groups and hydrophobic functional groups modified on the surface of the carbon fiber matrix, wherein the hydrophilic functional groups are selected from one or more of amino-substituted ionic liquid groups, hydroxyl groups and carboxyl groups.

[0006] A second aspect of the present invention provides a method for preparing an amphiphilic carbon fiber, comprising the following steps:

[0007] (1) oxidizing the carbon fiber to obtain oxidized carbon fiber;

[0008] (2) contacting the oxidized carbon fiber with a mixed solution containing an ionic liquid, a first organic solvent, a condensation agent, and a conductive agent to perform an electrochemical reaction to obtain a covalently grafted carbon fiber;

[0009] (3) The covalently grafted carbon fiber is mixed with a solution containing hydrophobic anions and immersed in the solution, and then dried to obtain the amphiphilic carbon fiber.

[0010] A third aspect of the present invention provides an amphiphilic carbon fiber obtained by the preparation method.

[0011] A fourth aspect of the present invention provides an application of the amphiphilic carbon fiber in thermoplastic composite materials and carbon fiber composite paper.

[0012] Through the above technical scheme, the present invention provides an amphiphilic carbon fiber and a preparation method thereof, which adopts electrochemical grafting of ionic liquid and uses ion exchange reaction to form amphiphilic carbon fiber, which can effectively improve the reaction efficiency. The interfacial shear strength of the obtained amphiphilic carbon fiber is greatly improved compared with that of unmodified carbon fiber, and the water dispersibility of carbon fiber can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The figure is a comparison chart of the dispersibility results of Example 2 and Comparative Examples 1 and 2.

[0014] Figure 2 Schematic diagram of the preparation of amphiphilic carbon fibers. DETAILED DESCRIPTION

[0015] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0016] A first aspect of the present invention provides an amphiphilic carbon fiber, wherein the amphiphilic carbon fiber comprises a carbon fiber matrix and hydrophilic functional groups and hydrophobic functional groups modified on the surface of the carbon fiber matrix, wherein the hydrophilic functional groups are selected from one or more of amino-substituted ionic liquid groups, hydroxyl groups and carboxyl groups.

[0017] In the present invention, an amphiphilic carbon fiber is provided, a carbon fiber matrix and a hydrophilic functional group and a hydrophobic functional group modified on the surface of the carbon fiber matrix. The surface of the carbon fiber is rich in oxygen-containing functional groups, while retaining hydrophilic hydroxyl and carboxyl groups, cations of ionic liquids are introduced as hydrophilic functional groups through the condensation of carboxyl groups and amino groups, and lipophilic anions are introduced through ion exchange of ionic liquids. The interfacial shear strength of the obtained amphiphilic carbon fiber is greatly improved compared to that of unmodified carbon fiber, and the water dispersibility of the carbon fiber can be improved.

[0018] In some specific embodiments of the present invention, the amphiphilic carbon fiber comprises: carbon fiber and hydrophilic functional groups and hydrophobic functional groups modified on the surface of the carbon fiber, which exist in the following manner: Figure 2 As shown, taking aminopropylaminopropyl-3-methylimidazolium chloride and sodium dodecyl sulfate as examples, the amphiphilic structure of the carbon fiber surface is illustrated, wherein the hydrophilic functional groups are ionized amino, carboxyl, hydroxyl and ionic liquid cations, and the hydrophobic functional groups are hydrophobic anions such as dodecyl sulfonate ions.

[0019] In some specific embodiments of the present invention, the amino-substituted ionic liquid group is selected from one or more of amino-substituted imidazolium cations, amino-substituted pyridinium cations, amino-substituted quaternary ammonium salt cations, amino-substituted quaternary phosphonium salt cations and amino-substituted pyrrole cations, and the hydrophobic functional group is selected from one or more of laurate ion, dodecyl sulfonate ion, decanoate ion, dioctyl dibutyrate sulfonate ion and bistrifluoromethanesulfonyl imide ion (LiNTf2).

[0020] Preferably, based on the total amount of the amphiphilic carbon fiber, the content of the hydrophilic functional group and the content of the hydrophobic functional group vary according to the actual feed amount, and the amphiphilicity actually varies according to the number of ionized hydrophilic groups, the number of condensations, and the number of substitutions.

[0021] In some specific embodiments of the present invention, the epoxy resin interfacial shear strength of the amphiphilic carbon fiber is 84-95MPa, the interlaminar shear strength of the polypropylene resin (POK) is 20-33MPa, the interlaminar shear strength of nylon 6 (PA6) is 58-68MPa, and the interlaminar shear strength of the aliphatic polyketone resin (POK) is 68-78MPa; the interfacial shear strength of the amphiphilic carbon fiber obtained by the present invention is greatly improved compared with that of the unmodified carbon fiber.

[0022] A second aspect of the present invention provides a method for preparing an amphiphilic carbon fiber, comprising the following steps:

[0023] (1) oxidizing carbon fiber to obtain oxidized carbon fiber (OCF);

[0024] (2) contacting the oxidized carbon fiber with a mixed solution containing an ionic liquid, a first organic solvent, a condensation agent and a conductive agent to perform an electrochemical reaction to obtain a covalently grafted carbon fiber (IL-OCF);

[0025] (3) The covalently grafted carbon fiber is mixed with a salt containing a hydrophobic anion and immersed in the mixture, and then dried to obtain the amphiphilic carbon fiber (DIL-OCF).

[0026] In the present invention, a method for preparing an amphiphilic carbon fiber is provided, wherein the carbon fiber is pretreated and then oxidized to obtain an oxidized carbon fiber having a hydrophilic oxygen-containing functional group on the surface, and the oxidized carbon fiber is added to an electrolyte of an amino-substituted ionic liquid and a condensing agent to perform electrolytic condensation, and an ion exchange reaction is performed after the reaction is completed, while retaining hydrophilic hydroxyl, carboxyl, and cation, an oleophilic anion is introduced to finally obtain the amphiphilic carbon fiber. The interfacial shear strength of the amphiphilic carbon fiber obtained by this method is greatly improved compared to that of unmodified carbon fiber, and the water dispersibility of the carbon fiber can be improved.

[0027] In some specific embodiments of the present invention, the carbon fiber is selected from carbon fiber tow or short carbon fiber.

[0028] In some specific embodiments of the present invention, before performing step (1), the carbon fiber is first subjected to a debonding treatment.

[0029] In some specific embodiments of the present invention, in step (1), the oxidation is carried out by contacting an electrolyte, wherein the electrolyte is selected from one or more aqueous solutions of ammonium bicarbonate, ammonium sulfate and ammonium nitrate, and the concentration of the electrolyte is 0.05-1 mol / L.

[0030] In some specific embodiments of the present invention, in step (1), the current density of the oxidation is 0.1-30A·m 2 , preferably 1-15A·m 2 The oxidation time is 1-30 min. The oxidation current density has good controllability and oxidation efficiency within this range.

[0031] In some specific embodiments of the present invention, in step (2), an electrochemical reaction is carried out using the oxidized carbon fiber as a cathode, graphite as an anode, and a mixed solution of an ionic liquid containing an amino group, a first organic solvent, a condensation agent and a conductive agent as an electrolyte, so as to covalently graft the ionic liquid on the surface of the carbon fiber.

[0032] In some specific embodiments of the present invention, in step (2), the cation of the amino-substituted ionic liquid is selected from one or more of amino-substituted imidazolium cations, amino-substituted pyridinium cations, amino-substituted quaternary ammonium salt cations, amino-substituted quaternary phosphonium salt cations and amino-substituted pyrrole cations; the anion is selected from one or more of halide ions, tetrafluoroborate ions, hexafluorophosphate ions and hexafluoroantimonate ions. By covalently grafting an ionic liquid containing an amino group on the surface of the carbon fiber, the interfacial shear strength of the carbon fiber can be significantly improved, and the water dispersibility of the chopped fiber can be improved. And suitable cations can be selected according to the actual application to obtain better material effects.

[0033] In some specific embodiments of the present invention, in step (2), the first organic solvent is selected from one or more of N,N-dimethylformamide (DMF), dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and carbon tetrachloride.

[0034] In some specific embodiments of the present invention, in step (2), the condensing agent is selected from one or more of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), O-benzotriazole-N,N,N',N'-tetramethyluronium tetrafluoroborate (TBTU), O-benzotriazole-tetramethyluronium hexafluorophosphate (HBTU), 1-hydroxybenzotriazole (HOBT), dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP).

[0035] In some specific embodiments of the present invention, in step (2), the conductive agent is selected from one or more of potassium chloride, potassium sulfate, sodium chloride and potassium nitrate.

[0036] In some specific embodiments of the present invention, in step (2), the mass ratio of the oxidized carbon fiber to the amino-substituted ionic liquid, the first organic solvent, the condensation agent and the conductive agent is 1:1-50:10-100:0.01-5:0.001-3.

[0037] In some specific embodiments of the present invention, in step (2), the current density of the electrochemical reaction is 0.1-30A×m 2 , the electrochemical reaction time is 0.1-300min.

[0038] In some specific embodiments of the present invention, the solution of the hydrophobic anion is obtained by dissolving the hydrophobic anion in the second solvent.

[0039] In some specific embodiments of the present invention, in step (3), the mass ratio of the covalently grafted carbon fiber to the salt containing the hydrophobic anion and the second solvent is 1:0.5-100:10-100.

[0040] In some specific embodiments of the present invention, the solution of the hydrophobic anion can also be obtained by dissolving the hydrophobic anion in a mixture of a second solvent and water, wherein the mass ratio of the second solvent to water is 5-95:5-95.

[0041] In some specific embodiments of the present invention, in step (3), the salt containing hydrophobic anions is selected from one or more of laurate, dodecyl sulfonate, decanoate, dioctyl dibutyrate sulfonate and bistrifluoromethanesulfonimide salt (LiNTf2), preferably dodecyl sulfonate and / or bistrifluoromethanesulfonimide salt. Different hydrophobic anion modifications can enhance different binding abilities of carbon fibers, and suitable anions can be selected according to practical applications to obtain better material effects.

[0042] In some specific embodiments of the present invention, in step (3), the second solvent is selected from one or more of dichloromethane, chloroform, ethanol, methanol and tetrahydrofuran.

[0043] In some specific embodiments of the present invention, in step (3), the mass ratio of the covalently grafted carbon fiber, the hydrophobic anion and the mixed solution is 1:0.5-100:10-100.

[0044] In some specific embodiments of the present invention, in step (3), the immersion is selected from ultrasound, microwave or stirring, wherein the power of ultrasound is 1-2000W, the power of microwave is 10-2000W, and the stirring rate is 10-2000rpm.

[0045] In some specific embodiments of the present invention, in step (3), the immersion time is 0.1-72 hours, and the immersion temperature is 0-55°C.

[0046] A third aspect of the present invention provides an amphiphilic carbon fiber obtained by the preparation method.

[0047] A fourth aspect of the present invention provides an application of the amphiphilic carbon fiber in thermoplastic composite materials and carbon fiber composite paper.

[0048] The present invention will be described in detail below through examples.

[0049] Aminopropyl-3-methylimidazolium chloride was purchased from a chemical synthesis reagent factory.

[0050] N-aminopropylpyridinium chloride was purchased from a chemical synthesis reagent factory.

[0051] Sodium dodecyl sulfate was purchased from Aladdin.

[0052] LiNTf2, HATU and HBTU were purchased from J&K.

[0053] Potassium chloride, sodium chloride, ammonium bicarbonate and ammonium bisulfate were purchased from Sinopharm.

[0054] DMF, DMAc, and DCM were purchased from Sinopharm.

[0055] 550E and 555H were purchased from Olin.

[0056] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0057] Example 1

[0058] The method for preparing amphiphilic carbon fiber comprises:

[0059] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0060] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bisulfate as the electrolyte, the temperature was 25 °C, and 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0061] (3) Take 1.2 g of oxidized carbon fiber as the cathode and graphite as the anode, and place them in a mixed solution containing 6 g of aminopropyl-3-methylimidazolium chloride, 100 mL of DMF, 18 mg of HATU and 10 mg of KCl at a temperature of 25 °C and a current density of 25 A×m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0062] (4) 0.6 g of IL-OCF was placed in 30 mL of dichloromethane, 1.2 g of LiNTf2 was added, and the mixture was immersed at 35 °C for 6 h. The carbon fiber was taken out, washed with ethanol and water, and dried to obtain DIL-OCF.

[0063] Example 2

[0064] The method for preparing amphiphilic carbon fiber comprises:

[0065] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0066] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bisulfate as the electrolyte, the temperature was 25 °C, and 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0067] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6 g of aminopropyl-3-methylimidazolium chloride, 100 mL of DMAC, 18 mg of HATU and 10 mg of KCl at a temperature of 25 °C and a current density of 5 A × m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0068] (4) 0.6 g of IL-OCF was placed in 30 mL of dichloromethane, 1.2 g of LiNTf2 was added, and the mixture was immersed at 35 °C for 6 h. The carbon fiber was taken out, washed with ethanol and water, and dried to obtain DIL-OCF.

[0069] Example 3

[0070] The method for preparing amphiphilic carbon fiber comprises:

[0071] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0072] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bisulfate as the electrolyte, the temperature was 25 °C, and 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0073] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6 g of aminopropyl-3-methylimidazolium chloride, 100 mL of DMAC, 18 mg of HBTU and 10 mg of KCl at a temperature of 25 °C and a current density of 25 A·m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0074] (4) 0.6 g of IL-OCF was placed in 30 mL of ethanol, 2.3 g of sodium dodecyl sulfate was added, and the mixture was immersed at 25° C. for 6 h. The carbon fiber was taken out, washed with ethanol and water, and dried to obtain DIL-OCF.

[0075] Example 4

[0076] The method for preparing amphiphilic carbon fiber comprises:

[0077] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0078] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bisulfate as the electrolyte, the temperature was 25 °C, and 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0079] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6 g of aminopropyl-3-methylimidazolium chloride, 100 mL of DMAC, 18 mg of HBTU and 10 mg of KCl at a temperature of 25 °C and a current density of 5 A·m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0080] (4) 0.6 g of IL-OCF was placed in 30 mL of dichloromethane, 1.2 g of LiNTf2 was added, and the mixture was immersed at 35 °C for 6 h. The carbon fiber was taken out, washed with ethanol and water, and dried to obtain DIL-OCF.

[0081] Example 5

[0082] The method for preparing amphiphilic carbon fiber comprises:

[0083] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0084] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bisulfate as the electrolyte, the temperature was 25 °C, and 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0085] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6.4 g of N-aminopropylpyridinium chloride, 100 mL of DMF, 18 mg of HATU and 10 mg of KCl at a temperature of 25 °C and a current density of 25 A·m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0086] (4) 0.6 g of IL-OCF was placed in 30 mL of dichloromethane, 1.2 g of LiNTf2 was added, and the mixture was immersed at 35 °C for 6 h. The carbon fiber was taken out, washed with ethanol and water, and dried to obtain DIL-OCF.

[0087] Example 6

[0088] The method for preparing amphiphilic carbon fiber comprises:

[0089] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0090] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bicarbonate as the electrolyte, the temperature was 25 °C, and the flow rate was 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0091] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6.4 g of N-aminopropylpyridinium chloride, 100 mL of DMF, 18 mg of HATU and 10 mg of NaCl at a temperature of 25 °C and a current density of 25 A·m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0092] (4) 0.6 g of IL-OCF was placed in 30 mL of ethanol, 2.3 g of sodium dodecyl sulfate was added, and the mixture was immersed at 25° C. for 6 h. The carbon fiber was taken out, washed with water, and dried to obtain DIL-OCF.

[0093] Example 7

[0094] The method for preparing amphiphilic carbon fiber comprises:

[0095] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0096] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, and 0.1 M ammonium bicarbonate as the electrolyte at 25 °C and 0.1 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0097] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6 g of aminopropyl-3-methylimidazolium chloride, 100 mL of DMF, 23 mg of HATU and 10 mg of KCl at a temperature of 25 °C and a current density of 25 A·m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0098] (4) 0.6 g of IL-OCF was placed in 30 mL of dichloromethane, 1.2 g of LiNTf2 was added, and the mixture was immersed at 35 °C for 6 h. The carbon fiber was taken out, washed with ethanol and water, and dried to obtain DIL-OCF.

[0099] Comparative Example 1

[0100] Commercial carbon fiber, grade SCF-35S.

[0101] Comparative Example 2

[0102] (1) passing the carbon fiber through a continuous heating furnace with an inert gas at a temperature of 500° C. for a reaction time of 10 min to obtain a debonded carbon fiber;

[0103] (2) The debonded carbon fiber was used as the anode, graphite as the cathode, 0.1 M ammonium bisulfate as the electrolyte, the temperature was 25 °C, and 2.0 A·m 2 Under current conditions, electrolysis was performed for 5 minutes to obtain OCF.

[0104] (3) 1.2 g of oxidized carbon fiber was used as the cathode and graphite was used as the anode. The mixture was placed in a mixed solution containing 6.0 g of 6.4 g of N-aminopropylpyridinium chloride, 100 mL of DMF, 18 mg of HATU and 10 mg of NaCl at a temperature of 25 °C and a current density of 25 A·m 2 The reaction was conducted under the conditions of 100 ℃ and 200 ℃ for 2 h, and then washed with DMF and deionized water for several times and dried to obtain IL-OCF.

[0105] Dispersion test:

[0106] The water dispersibility test was performed on Example 2 and Comparative Examples 1 and 2. Figure 1 As shown, it can be seen from the results that the amphiphilic carbon fiber of Example 2 has better dispersibility in water, while the commercial carbon fiber, i.e., Comparative Example 1, has the worst dispersibility. Comparative Example 2 has better hydrophilicity due to the grafting of ionic liquid and can be dispersed in water, but its uniformity is not as good as that of the amphiphilic carbon fiber.

[0107] Interface performance test:

[0108] Interlaminar shear strength test method: a single fiber is fixed on a homemade glass mold, a small amount of thermoplastic resin (such as polypropylene resin (POK), nylon 6 (PA6), aliphatic polyketone resin (POK) in the present invention) is dipped with a needle tip and applied to the fiber to form a point, and then heated and melted at 300°C on a flat vulcanizer to spontaneously form microbeads. According to the micro-debonding measurement method, the interlaminar shear strength is tested, and the microbead coating length is observed under a microscope. Fibers with a coating length between 100-170 μm are selected and passed through a homemade fixture with micropores, and the microbeads are fixed in the micropores of the fixture. The fixture is placed on a single fiber strength tester, the length is set to 10 mm, and the tensile speed is set to 2 mm / min. The interlaminar shear strength of polypropylene resin (POK), the interlaminar shear strength of nylon 6 (PA6), and the interlaminar shear strength of aliphatic polyketone resin (POK) are measured respectively.

[0109] Epoxy resin interface shear strength: 550E epoxy resin, 555H curing agent and 2-ethylimidazole accelerator are mixed in a certain proportion to obtain a resin mixture, and the resin mixture is applied to the surface of the modified carbon fiber to prepare a composite material. The epoxy resin interface shear strength of the composite material is obtained.

[0110] The amphiphilic carbon fibers obtained in the embodiments and comparative examples were subjected to interface strength tests, such as epoxy resin interface shear strength, polypropylene interlayer shear strength (PP interlayer shear strength, brand M800E), nylon 6 interlayer shear strength (PA6 interlayer shear strength, brand BL3190H) and aliphatic polyketone resin interlayer shear strength (POK interlayer shear strength, brand Korea Hyosung M330A), and the results are shown in Table 1.

[0111] Table 1

[0112]

[0113]

[0114] It can be seen from the results of Table 1 that for epoxy resin, the carbon fibers obtained by the present invention all have good interfacial bonding ability, and Examples 1-6 are all improved to varying degrees compared to conventional commercial carbon fibers. Example 7 is because the current in step (1) is small, the surface is not fully activated and oxidized, and there are few active groups, resulting in a low subsequent grafting modification ratio, and finally a weak ability to bind epoxy. Comparative Example 2 has a high interfacial shear strength because no ion exchange reaction is performed, and the hydrophobic anions do not significantly improve the binding with the epoxy resin, but instead have a certain weakening effect, so such a result is presented. Therefore, the present application can set different anions for the binding of different resins in a targeted manner.

[0115] For PP, as shown in Examples 3 and 6, the hydrophobic anion of dodecyl sulfonate has the best effect, because its long hydrophobic chain can be well combined with PP. - It also has a good PP interlaminar shear strength effect, but is weaker than dodecyl sulfonate. Comparative Example 2 without hydrophobic anions is improved relative to Comparative Example 1, because the effect of the imidazole ring and PP is stronger than that of ordinary carbon fibers.

[0116] For PA6, the more carboxyl groups and hydroxyl groups on the surface of the carbon fiber, the better the interlayer shear strength of PA6. The amide bond generated by the grafted ionic liquid can also form a good bond with PA6, so the bonding ability of the carbon fiber in comparative example 1 is improved. - The binding ability with PA6 is higher than that of dodecyl sulfonate, so the data in the table are presented.

[0117] POK is a thermoplastic resin with more aromatic rings, so it combines better with pyridine rings, but imidazole also has directionality, so the modified fibers all have improved binding ability. Example 7 has the best effect because it is less modified and is closest to carbon fiber. The carbon fiber's turbostratic graphite structure has aromaticity and combines best with POK.

[0118] In summary, the advantage of the amphiphilic carbon fiber described in the present invention is that it has a relatively good binding ability with various resins and has good water dispersibility, and carbon fibers with different modified structures can be designed according to different resins to improve the binding ability with the corresponding resin.

[0119] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An amphiphilic carbon fiber, characterized in that: The amphiphilic carbon fiber comprises a carbon fiber matrix and hydrophilic functional groups and hydrophobic functional groups modified on the surface of the carbon fiber matrix, wherein the hydrophilic functional groups are selected from one or more of amino-substituted ionic liquid groups, hydroxyl groups and carboxyl groups.

2. The amphiphilic carbon fiber according to claim 1, wherein The amino-substituted ionic liquid group is selected from one or more of an amino-substituted imidazolium cation, an amino-substituted pyridinium cation, an amino-substituted quaternary ammonium salt cation, an amino-substituted quaternary phosphonium salt cation and an amino-substituted pyrrole cation; Preferably, the hydrophobic functional group is selected from one or more of laurate ion, dodecyl sulfonate ion, decanoate ion, dioctyl dibutyrate sulfonate ion and bistrifluoromethanesulfonimide ion.

3. The amphiphilic carbon fiber according to claim 1 or 2, wherein The epoxy resin interface shear strength of the amphiphilic carbon fiber is 84-95 MPa, the polypropylene interlayer shear strength is 20-33 MPa, the nylon 6 interlayer shear strength is 58-68 MPa, and the aliphatic polyketone resin interlayer shear strength is 68-78 MPa.

4. A method for preparing amphiphilic carbon fiber, characterized in that: The steps include: (1) oxidizing the carbon fiber to obtain oxidized carbon fiber; (2) contacting the oxidized carbon fiber with a mixed solution containing an amino-substituted ionic liquid, a first organic solvent, a condensation agent, and a conductive agent to perform an electrochemical reaction to obtain a covalently grafted carbon fiber; (3) The covalently grafted carbon fiber is mixed with a salt containing a hydrophobic anion and immersed in the mixture, and then dried to obtain the amphiphilic carbon fiber.

5. The preparation method according to claim 4, wherein: The carbon fiber is selected from carbon fiber tow or short carbon fiber; Preferably, before performing step (1), the carbon fibers are first subjected to a degumming treatment.

6. The preparation method according to claim 4 or 5, wherein: In step (1), the oxidation is carried out by contacting an electrolyte, wherein the electrolyte is selected from one or more aqueous solutions of ammonium bicarbonate, ammonium sulfate and ammonium nitrate; Preferably, in step (1), the oxidation current density is 0.1-30A×m 2 , preferably 1-15A×m 2 , the oxidation time is 1-30min.

7. The preparation method according to any one of claims 4 to 6, wherein: In step (2), the amino-substituted ionic liquid is selected from one or more of an amino-substituted imidazolium cation, an amino-substituted pyridinium cation, an amino-substituted quaternary ammonium salt cation, an amino-substituted quaternary phosphonium salt cation and an amino-substituted pyrrole cation; the anion is selected from one or more of a halide ion, a tetrafluoroborate ion, a hexafluorophosphate ion and a hexafluoroantimonate ion; Preferably, in step (2), the first organic solvent is selected from one or more of N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran and carbon tetrachloride; Preferably, in step (2), the condensing agent is selected from one or more of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, O-benzotriazole-N,N,N',N'-tetramethyluronium tetrafluoroboric acid, O-benzotriazole-tetramethyluronium hexafluorophosphate, 1-hydroxybenzotriazole, dicyclohexylcarbodiimide and 4-dimethylaminopyridine; Preferably, in step (2), the conductive agent is selected from one or more of potassium chloride, potassium sulfate, sodium chloride and potassium nitrate.

8. The preparation method according to any one of claims 4 to 7, wherein: In step (2), the mass ratio of the oxidized carbon fiber to the amino-substituted ionic liquid, the first organic solvent, the condensation agent and the conductive agent is 1:1-50:10-100:0.01-5:0.001-3; Preferably, in step (2), the current density of the electrochemical reaction is 0.1-30A·m 2 , the electrochemical reaction time is 0.1-300min.

9. The preparation method according to any one of claims 4 to 8, wherein: The solution of the hydrophobic anion is obtained by dissolving the hydrophobic anion in a second solvent; Preferably, in step (3), the mass ratio of the covalently grafted carbon fiber, the salt containing the hydrophobic anion, and the second solvent is 1:0.5-100:10-100; Preferably, in step (3), the salt containing a hydrophobic anion is selected from one or more of laurate, dodecyl sulfonate, decanoate, dioctyl dibutyrate sulfonate and bistrifluoromethanesulfonimide salt; Preferably, in step (3), the second solvent is selected from one or more of dichloromethane, chloroform, ethanol, methanol and tetrahydrofuran.

10. The preparation method according to any one of claims 4 to 9, wherein: In step (3), the immersion method is selected from ultrasound, microwave or stirring; wherein the power of ultrasound is 1-2000W, the power of microwave is 10-2000W, the stirring rate is 10-2000rpm, the immersion time is 0.1-72h, and the immersion temperature is 0-55°C.

11. An amphiphilic carbon fiber obtained by the preparation method according to any one of claims 4 to 10.

12. Use of the amphiphilic carbon fiber according to any one of claims 1 to 3 and 11 in thermoplastic composite materials and carbon fiber composite paper.

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