Composite Fiber and Method for Manufacturing the Same

This application claims under 35 U.S.C. § 119 (a) the benefit of Korean Patent Application No. 10-2024-0061079 filed on May 9, 2024 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

The present disclosure relates to composite fibers and methods for their manufacture, specifically focusing on composite fibers incorporating MXene materials. These composite fibers exhibit enhanced mechanical, thermal, and electrical properties, making them suitable for applications in textiles, electronics, and advanced materials engineering. The disclosure also covers the formulation and application of various coating layers, as well as the manufacturing processes including plying, twisting, and surface treatments, to improve the fiber's durability and performance.

MXene is a novel two-dimensional material having high electrical conductivity and electrochemical properties similar to the electrical conductivity and electrochemical properties of metals. MXene exhibits excellent performance in various fields, such as electrochemical energy storage devices, electrodes, gas and moisture sensors, and conductive fillers.

Also, MXene has excellent dispersibility due to hydrophilic functional groups on the surface thereof. Therefore, highly dispersed MXene solutions may also be produced by weaving. However, compared to the excellent performance of a single MXene sheet, fibers comprising a structure have weak mechanical properties and very poor oxidation stability. Therefore, in order to use MXene as an electrical wire, an electrical and heating material, and a wearable electronic material, further improved chemical stabilization and mechanical properties should be secured.

An aspect of the present disclosure is to provide a composite fiber having improved oxidation prevention and durability of MXene and a method for manufacturing the same.

Another aspect of the present disclosure is to provide a composite fiber having improved elongation and tensile strength of MXene and a method for manufacturing the same.

Another aspect of the present disclosure is to provide a composite fiber having high stability against external stimuli and a method for manufacturing the same.

In one aspect, a composite fiber is provided that comprises: 1) a MXene polymer fiber comprising a first polymer comprising d MXene; 2) a first coating layer on the MXene polymer fiber; 3) a second polymer and disposed on a surface of the first coating layer; and 4) a second coating layer on the first coating layer and the second polymer.

In certain aspects, the first polymer and/or the second polymer may comprises fiber forms. In certain aspects, the MXene may be distributed throughout the first polymer. In certain aspects, the MXene may be distributed inside the first polymer.

According to a preferred aspect of the present disclosure, a composite fiber includes: a MXene polymer fiber including a first polymer having a shape of a fiber and MXene distributed inside the first polymer; a first coating layer on the MXene polymer fiber; a second polymer having a shape of a fiber and disposed on a surface of the first coating layer; and a second coating layer on the first coating layer and the second polymer.

In aspects, the first polymer may include polyacrylonitrile (PAN).

In certain preferred aspects, a content of the MXene may be 20 to 40 wt % based on a total weight of the MXene polymer fiber.

In certain preferred aspects, in the MXene polymer fiber, MXene may include a plurality of, MXene nanosheet laminates, and the first polymer is disposed between the nanosheets. In such a configuration, MXene may be considered within the first polymer.

In preferred aspexts, in the MXene polymer fiber, the first polymer and the MXene may be combined by an electrostatic interaction.

In certain preferred aspects, the first coating layer may include benzoic acid-based organic molecules.

In certain preferred aspects, fineness of the second polymer may be 50 to 100d.

In certain preferred aspects, the MXene polymer fiber coated with the first coating layer and the second polymer may have a structure in which twists are repeated.

In certain aspects, the second coating layer may be a thermoplastic polymer having a thermal strain of 80° C. or higher and a degree of polymerization of 1,000 to 1,000,000.

In certain aspects, based on a total weight of the composite fiber, the MXene polymer fibermay be included in an amount of 0.5 to 2 wt %, the second polymer may be included in an amount of 96 to 99 wt %, and the second coating layer may be included in an amount of 0.8 to 3.5 wt %.

In certain aspects, the composite fiber may have tensile strength of 90 MPa or more and elongation of 17% or more.

In certain aspects, the composite fiber may have a diameter of 10 to 300 μm.

According to another aspect of the present disclosure, a method for manufacturing a composite fiber is provided and suitably includes: mixing MXene and a first polymer to obtain a MXene polymer fiber; depositing a first coating layer on the MXene polymer fiber; a plying and twisting operation of plying and twisting the MXene polymer fiber and the second polymer to obtain a ply yarn; and obtaining a second coating layer on the plied yarn.

The obtaining of the MXene polymer fiber suitably may include: preparing a first dispersion including MXene and a first solvent; preparing a second dispersion including a first polymer and a second solvent; obtaining a mixed solution including the first dispersion and the second dispersion; and a wet spinning operation of wet spinning the mixed solution to obtain a MXene polymer fiber.

The first solvent and the second solvent suitably may each be independently at least one selected from the group consisting of methylpyrrolidone (1-methyl-2-pyrrolidinone-N-methyl-2-pyrrolidone (NMP)), dimethylformamide (N, N-dimethylformamide (DMF)), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO).

In aspects, the MXene polymer fiber suitably may include a substrate including a first polymer and having a shape of a fiber and MXene distributed inside the substrate, and includes 20 to 40 wt % of the MXene.

In aspects, the obtaining of the first coating layer may include immersing the MXene polymer fiber in a surface treatment solution including benzoic acid-based organic molecules.

In aspects, the immersing suitably may be performed at 80° C. or higher for 30 minutes or longer.

In some aspects, the plying and twisting may include plying the MXene polymer fiber and the second polymer and then rotating and twisting the entire fiber.

In some aspects, the obtaining of the second coating layer may include immersing the plied yarn in a surface treatment solution including the second polymer and then performing drying.

In some embodiments, a composite fiber includes a core comprising a MXene polymer fiber where the MXene is distributed as stacked nanosheets within a first polymer. The fiber has a first coating layer of benzoic acid-based organic molecules, a second polymer in fiber form on the first coating layer, and a second coating layer of a thermoplastic polymer with a thermal strain of about 80° C. or higher. The first polymer may comprise polyacrylonitrile (PAN). The content of the MXene may be about 20 to 40 wt % based on the total weight of the MXene polymer fiber. In the MXene polymer fiber, the first polymer and the MXene may be combined by electrostatic interaction. The first coating layer may comprise benzoic acid-based organic molecules. The fineness of the second polymer may be about 50 to 100d. The MXene polymer fiber coated with the first coating layer and the second polymer may have a structure in which twists are repeated. The composite fiber may have a tensile strength of about 90 MPa or more and an elongation of about 17% or more.

In some embodiments, a composite fiber includes a core comprising a MXene polymer fiber, where the MXene is distributed within a first polymer as stacked nanosheets with the first polymer filling the spaces between the nanosheets. The fiber has a first coating layer of benzoic acid-based organic molecules, a second polymer in fiber form on the first coating layer, and a second coating layer of a thermoplastic polymer with a thermal strain of about 80° C. or higher. The first polymer may comprise polyacrylonitrile (PAN), and the second polymer may comprise nylon, polyethylene terephthalate (PET), polyethylene (PE), aramid, cotton, polyimide (PI), polyacrylic acid (PAA), or a combination thereof.

The method for manufacturing a composite fiber may involve mixing MXene and a first polymer to obtain a MXene polymer fiber, depositing a first coating layer on the MXene polymer fiber, performing a plying and twisting operation with a second polymer to obtain a ply yarn, and applying a second coating layer on the plied yarn. The method may include preparing a first dispersion comprising MXene and a first solvent, preparing a second dispersion comprising a first polymer and a second solvent, obtaining a mixed solution of the first and second dispersions, and performing a wet spinning operation to obtain a MXene polymer fiber. The first solvent and the second solvent may each independently be selected from methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO). The MXene polymer fiber may comprise a substrate comprising a first polymer in the shape of a fiber with MXene distributed inside, and may contain about 20 to 40 wt % of MXene. The first coating layer may be obtained by immersing the MXene polymer fiber in a surface treatment solution comprising benzoic acid-based organic molecules at about 80° C. or higher for about 30 minutes or longer. The plying and twisting may involve plying the MXene polymer fiber and the second polymer and then rotating and twisting the entire fiber. The second coating layer may be obtained by immersing the plied yarn in a surface treatment solution comprising the second polymer and then performing drying.

As discussed, the method and system suitably include use of a controller or processer.

The objects described above, as well as other objects, features, and advantages, will be clearly understood from the following preferred embodiments with reference to the attached drawings. However, the present disclosure is not limited to the embodiments, and may be embodied in different forms. The embodiments are suggested only to offer a thorough and complete understanding of the disclosed context and to sufficiently inform those skilled in the art of the technical concept of the present disclosure.

Like reference numbers refer to like elements throughout the description of the figures. In the drawings, the sizes of structures may be exaggerated for clarity. It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be construed as being limited by these terms, which are used only to distinguish one element from another. For example, within the scope defined by the present disclosure, a “first” element may be referred to as a “second” element, and similarly, a “second” element may be referred to as a “first” element. Singular forms are intended to include plural forms as well, unless the context clearly indicates otherwise.

It will be further understood that terms, such as “comprise” or “has,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. In addition, it will be understood that, when an element, such as a layer, film, region, or substrate is referred to as being “on” another element, it may be directly on the other element, or an intervening element may also be present. It will also be understood that when an element, such as a layer, film, region, or substrate is referred to as being “under” another element, it may be directly under the other element, or an intervening element may also be present.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. These terms are merely intended to distinguish one component from another component, and the terms do not limit the nature, sequence or order of the constituent components. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. In addition, the terms “unit”, “-er”, “-or”, and “module” described in the specification mean units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof.

Although exemplary embodiment is described as using a plurality of units to perform the exemplary process, it is understood that the exemplary processes may also be performed by one or plurality of modules. Additionally, it is understood that the term controller/control unit refers to a hardware device that includes a memory and a processor and is specifically programmed to execute the processes described herein. The memory is configured to store the modules and the processor is specifically configured to execute said modules to perform one or more processes which are described further below.

Further, the control logic of the present disclosure may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN).

Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about”.

Unless the context clearly indicates otherwise, all numbers, figures, and/or expressions that represent ingredients, reaction conditions, polymer compositions, and amounts of mixtures used in the specification are approximations that reflect various uncertainties of measurement occurring inherently in obtaining these figures, among other things. For this reason, it should be understood that, in all cases, the term “about” should be understood to modify all such numbers, figures and/or expressions. In addition, when numerical ranges are disclosed in the description, these ranges are continuous, and include all numbers from the minimum to the maximum, including the maximum within each range, unless otherwise defined. Furthermore, when a range refers to an integer, it includes all integers from the minimum to the maximum, including the maximum within the range, unless otherwise defined.

is a diagram illustrating a cross-section of a composite fiber, which is an embodiment of the present disclosure, andis a diagram illustrating an SEM cross-section of the composite fiber, which is an embodiment of the present disclosure.

Referring toand/or, the composite fiber, which is an embodiment of the present disclosure, includes a MXene polymer fiberincluding a first polymer having the shape of a fiber and MXene distributed inside the first polymer; a first coating layercoated on the MXene polymer fiber; a second polymerhaving the shape of a fiber and disposed on a surface of the first coating layer; and a second coating layercoated on the first coating layerand the second polymer.

MXene is a new two-dimensional material having high electrical conductivity and electrochemical properties similar to metals. MXene has a hydrophilic surface and due to negatively charged functional groups (OH, O, F), MXene has excellent dispersibility and is easy to assemble into a structure. In addition, since MXene does not require post-processing like graphene oxide, the expected cost of the process is low. In the case of fibers manufactured as a structure, electrical and mechanical properties are significantly reduced. The reason why these physical properties are weak is because the MXene is formed of a plurality of stacked nanosheets and has low bonding strength due to pores between nanosheets inside the MXene.

Therefore, in an embodiment of the present disclosure, in order to solve the weak physical properties of MXene as described above, in the MXene polymer fiber, MXene is a plurality of nanosheets being stacked, and the first polymer fills between the nanosheets, and the first polymer fills pores between the nanosheets to have improved physical properties.

In an embodiment, based on the total weight of the MXene polymer fiber, the content of the MXene may be 20 to 40 wt %. If the content of MXene is less than 20 wt %, electrical conductivity may be reduced due to high resistance, and if the content of MXene exceeds 40 wt %, MXene may act as an impurity and cause radioactivity problems, such as fiber breakage when forming a fiber structure.

The first polymer may include monomers having a nitrile functional group and a polymer polymerized with a monomer having a nitrile functional group. For example, it may be polyacrylonitrile (PAN).

In the MXene polymer fiber, the first polymer and the MXene may be combined by electrostatic interaction.

In the MXene polymer fiber, a hydroxyl group, which is a functional group of the MXene, and the nitrile functional group, which is the functional group of the first polymer, may be combined by electrostatic interaction, thereby increasing the dispersibility of the composite fiber.

The MXene polymer fibermay have a circular, oval, hollow, or flat cross-sectional shape. Specifically, in the present disclosure, the circular and flat types may have an aspect ratio of 1 to 30.