WO2019222175A1 - Fibres de graphène continues à partir de feuilles de graphène fonctionnalisées - Google Patents

Fibres de graphène continues à partir de feuilles de graphène fonctionnalisées Download PDF

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Publication number
WO2019222175A1
WO2019222175A1 PCT/US2019/032165 US2019032165W WO2019222175A1 WO 2019222175 A1 WO2019222175 A1 WO 2019222175A1 US 2019032165 W US2019032165 W US 2019032165W WO 2019222175 A1 WO2019222175 A1 WO 2019222175A1
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Prior art keywords
graphene
fiber
long fiber
graphene sheets
continuous
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PCT/US2019/032165
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English (en)
Inventor
Aruna Zhamu
Bor Z. Jang
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Nanotek Instruments, Inc.
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Priority claimed from US15/978,712 external-priority patent/US10865502B2/en
Priority claimed from US15/978,730 external-priority patent/US20190345647A1/en
Application filed by Nanotek Instruments, Inc. filed Critical Nanotek Instruments, Inc.
Publication of WO2019222175A1 publication Critical patent/WO2019222175A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/194—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/19—Preparation by exfoliation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/198—Graphene oxide

Definitions

  • the present disclosure relates generally to the field of graphene fibers and, more particularly, to a new class of continuous graphene fibers produced from functionalized graphene sheets.
  • This new class of fibers exhibits a combination of exceptionally high tensile strength, elastic modulus, thermal conductivity, and electrical conductivity.
  • Carbon fibers and graphite fibers are produced from pitch, polyacrylonitrile (PAN), and rayon. Most carbon fibers (about 90%) are made from PAN fibers. A small amount (about 10%) is manufactured from petroleum pitch or rayon. Although the production of carbon fibers from different precursors requires different processing conditions, the essential features are very similar. Generally, carbon fibers are manufactured by a controlled pyrolysis of stabilized precursor fibers. Precursor fibers (e.g. PAN) are first stabilized at about 200-400°C in air by an oxidization process.
  • PAN polyacrylonitrile
  • the resulting infusible, stabilized fibers are then subjected to a high temperature treatment at approximately 1,000- l,500°C (up to 2,000°C in some cases) in an inert atmosphere to remove hydrogen, oxygen, nitrogen, and other non-carbon elements.
  • This step is often called carbonization and it can take 2-24 hours to complete, depending upon the carbonization temperature and the starting material used.
  • Carbonized fibers can be further graphitized at an even higher temperature, up to around 3,000 °C to achieve higher carbon content and higher degree of graphitization, mainly for the purpose of achieving higher Young’s modulus or higher strength in the fiber direction. This takes another 1-4 hours under strictly controlled atmosphere and ultra-high temperature conditions.
  • the properties of the resulting carbon/graphite fibers are affected by many factors, such as crystallinity, crystallite sizes, molecular orientation, carbon content, and the type and amount of defects.
  • the carbon fibers can be heat-treated to become high modulus graphite fibers (from pitch) or high strength carbon fibers (from PAN-based).
  • Carbon fibers heated in the range from 1500-2000 °C (carbonization) exhibits the highest tensile strength (5,650 MPa), while carbon fiber heated from 2500 to 3000 °C (graphitizing) exhibits a higher modulus of elasticity (531 GPa).
  • the tensile strength of carbon/graphite fibers is typically in the range from 1-6 GPa, and the Young’s modulus is typically in the range from 100-588 GPa.
  • carbon/graphite fibers can be roughly classified into ultra-high modulus (>500 GPa), high modulus (>300 GPa), intermediate modulus (>200 GPa), low modulus (100 GPa), and high strength (>4 GPa) carbon fibers.
  • Carbon fibers can also be classified, based on final heat treatment temperatures, into type I (2,000 °C heat treatment), type II (1,500 °C heat treatment), and type III (1,000 °C heat treatment).
  • Type II PAN-based carbon fibers are usually high strength carbon fibers, while most of the high modulus carbon fibers belong to type I from pitch.
  • Carbon is known to have five unique crystalline structures, including diamond, fullerene (0-D nanographitic material), carbon nanotube or carbon nanofiber (l-D nanographitic material), graphene (2-D nanographitic material), and graphite (3-D graphitic material, including graphite fiber).
  • the carbon nanotube (CNT) refers to a tubular structure grown with a single wall or multi-wall.
  • Carbon nanotubes (CNTs) and carbon nano fibers (CNFs) have a diameter on the order of a few nanometers to a few hundred nanometers.
  • Their longitudinal, hollow structures impart unique mechanical, electrical and chemical properties to the material.
  • the CNT or CNF is a one-dimensional nanocarbon or l-D nanographite material.
  • these yams are not considered as“continuous fibers”. They are twisted aggregates of individual CNTs or CNFs (each being but a few microns long) that are not self-bonded together; instead, they are mechanically fastened together as a yam.
  • Bulk natural graphite is a 3-D graphitic material with each particle being composed of multiple grains (a grain being a graphite single crystal or crystallite) with grain boundaries (amorphous or defect zones) demarcating neighboring graphite single crystals.
  • Each grain is composed of multiple graphene planes that are oriented parallel to one another.
  • a graphene plane in a graphite crystallite is composed of carbon atoms occupying a two-dimensional, hexagonal lattice. In a given grain or single crystal, the graphene planes are stacked and bonded via van der Waal forces in the crystallographic c-direction (perpendicular to the graphene plane or basal plane).
  • the graphene planes in one grain are parallel to one another, typically the graphene planes in one grain and the graphene planes in an adjacent grain are different in orientation. In other words, the orientations of the various grains in a graphite particle typically differ from one grain to another.
  • a graphite single crystal (crystallite) per se is anisotropic with a property measured along a direction in the basal plane (crystallographic a- or h-axis direction) being dramatically different than if measured along the crystallographic c-axis direction (thickness direction).
  • the thermal conductivity of a graphite single crystal can be up to approximately 1,920 W/mK (theoretical) or 1,800 W/mK (experimental) in the basal plane (crystallographic a- and h-axis directions), but that along the crystallographic c-axis direction is less than 10 W/mK (typically less than 5 W/mK).
  • the multiple grains or crystallites in a graphite particle are typically all oriented along different directions. Consequently, a natural graphite particle composed of multiple grains of different orientations exhibits an average property less than 200 W/mK.
  • a bulk graphite-derived object or graphitic fiber having sufficiently large dimensions and having all graphene planes being essentially parallel to one another along one desired direction (e.g. along the fiber axis).
  • the constituent graphene planes of a graphite crystallite can be exfoliated and extracted or isolated from a graphite crystallite to obtain individual graphene sheets of carbon atoms provided the inter-planar van der Waals forces can be overcome.
  • An isolated, individual graphene sheet of carbon atoms is commonly referred to as single-layer graphene.
  • a stack of multiple graphene planes bonded through van der Waals forces in the thickness direction with an inter-graphene plane spacing of 0.3354 nm is commonly referred to as a multi-layer graphene.
  • a multi-layer graphene platelet has up to 300 layers of graphene planes ( ⁇ 100 nm in thickness), but more typically up to 30 graphene planes ( ⁇ 10 nm in thickness), even more typically up to 20 graphene planes ( ⁇ 7 nm in thickness), and most typically up to 10 graphene planes (commonly referred to as few-layer graphene in scientific community).
  • Single-layer graphene and multi layer graphene sheets are collectively called“nanographene platelets” (NGPs).
  • NGPs nanostructureene platelets
  • Graphene sheets/platelets or NGPs are a new class of carbon nanomaterial (a 2-D nanocarbon) that is distinct from the 0-D fullerene, the l-D CNT, and the 3-D graphite
  • graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations.
  • Aqueous graphene oxide liquid crystals can then be continuously spun into meters of macroscopic graphene oxide fibers, which are chemically reduced to obtain RGO fibers.
  • the GO dispersions were loaded into glass syringes and injected into the NaOH/methanol solution under the conditions of 1.5 MPa N 2 .
  • the NaOH/methanol solution is a coagulation solution (a non-solvent for GO) and the GO sheets are precipitated out in a loosely connected, very low density fiber.
  • the fibers produced in the coagulation bath were then rolled onto a drum, washed by methanol to remove the salt, and dried for 24 hours at room temperature.
  • the as-prepared GO fibers were then chemically reduced in the aqueous solution of hydro-iodic acid (40 %) at 80°C for 8 hours, followed by washing with methanol and vacuum drying for 12 hours.
  • a specific object of the present disclosure is to provide a graphene-derived continuous or long graphene fiber that is composed of functionalized graphene sheets that are chemically bonded or interconnected together, not just an aggregate of discrete graphene sheets.
  • the present disclosure provides a graphene-based continuous or long fiber comprising chemically functionalized graphene sheets that are chemically bonded or interconnected with one another having an inter-planar spacing doo 2 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content (e.g. H, O, N, B, P, Cl, F, Br, I, S, etc.) of 0.1% to 47% by weight, wherein the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core-shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from 1.5 to 2.2 g/cm .
  • a non-carbon element content e.g. H, O, N, B, P, Cl, F, Br, I, S, etc.
  • This long fiber can be an essentially“continuous fiber” wound as a spool on a roller and having a length up to several kilometers (e.g. 10 km).
  • the graphene sheets are typically interconnected with one another via chemical bonding or reactions between the chemically active functional groups attached to respective adjacent graphene sheets. These chemically active functional groups are capable of reacting with neighboring groups by forming covalent bonds, hydrogen bonds, and/or p-p bonds.
  • the present disclosure also provides a process for producing a graphene -based continuous or long fiber from chemically functionalized graphene sheets.
  • the process comprises:
  • a liquid medium e.g. water or an organic solvent
  • the chemically functionalized graphene sheets contain chemical functional groups attached thereto (on graphene sheet surfaces and/or edges) and a non-carbon element content of 0.1% to 47% by weight;
  • dispersion onto a supporting substrate wherein the dispensing and depositing procedure includes mechanical shear stress-induced alignment of the chemically functionalized graphene sheets along the filament axis direction, and partially or completely removing the liquid medium from the filament to form a continuous or long fiber comprising aligned chemically functionally graphene sheets;
  • the long graphene fiber comprises chemically functionalized graphene sheets that are chemically bonded with one another having an inter-planar spacing doo2 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content of 0.1% to 40% by weight and wherein the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core-shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from 1.5 to 2.2 g/cm .
  • electromagnetic waves e.g. radio frequency waves, or microwaves
  • UV light e.g., UV light
  • high-energy radiation e.g. electron beam, Gamma ray, or X-ray
  • the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core-shell structure, have no helically arranged graphene domains, and have a length
  • the process may further comprise a step of compressing the continuous or long fiber (after step (b) or (c)) to increase a degree of graphene sheet orientation and physical density, and to improve contact between chemically functionalized graphene sheets. This would also facilitate chemical interconnection between graphene sheets.
  • the disclosure also provides a process for producing a graphene-based long fiber from graphene sheets.
  • the process comprises:
  • dispersion onto a supporting substrate wherein the dispensing and depositing procedure includes mechanical shear stress-induced alignment of the graphene sheets along a filament axis direction, and partially or completely removing the fluid medium from the filament to form a continuous or long fiber comprising aligned graphene sheets;
  • the process may further comprise a step of compressing the continuous or long fiber (after step (c) or (d)) to increase a degree of graphene sheet orientation and physical density, and to improved contact between chemically functionalized graphene sheets.
  • the chemically functionalized graphene sheets in the long fiber contain a chemical functional group selected from the group consisting of alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, carboxylic group, amine group, sulfonate group (— S0 3 H), aldehydic group, quinoidal, fluorocarbon, derivatives thereof, and combinations thereof.
  • a chemical functional group selected from the group consisting of alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, carboxylic group, amine group, sulfonate group (— S0 3 H), aldehydic group, quinoidal, fluorocarbon, derivatives thereof, and combinations thereof.
  • the chemically functionalized graphene sheets contain a chemical functional group selected from an oxygenated group consisting of hydroxyl, peroxide, ether, keto, aldehyde, and combinations thereof.
  • the chemically functionalized graphene sheets contain a chemical functional group selected from the group consisting of -S0 3 H, -COOH, -NH 2 , -OH, - R'CHOH, -CHO, -CN, -COC1, halide, -COSH, -SH, -COOR', -SR', -SiR' 3 , -Si(-OR'-) y R' 3 -y, - Si(— O— SiR' 2 — )OR', -R", Li, AlR' 2 , Hg— X, TlZ 2 and Mg— X; wherein y is an integer equal to or less than 3, R' is hydrogen, alkyl, aryl, cycloalkyl, or aralkyl, cycloaryl, or poly (alky lether), R" is fluoroalkyl, fluoroaryl, fluorocycloalkyl, fluoroaralkyl or
  • the chemically functionalized graphene sheets contain a chemical functional group selected from the group consisting of amidoamines, polyamides, aliphatic amines, modified aliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides, ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxy adduct, phenolic hardener, non-brominated curing agent, non-amine curatives, derivatives thereof, and combinations thereof.
  • a chemical functional group selected from the group consisting of amidoamines, polyamides, aliphatic amines, modified aliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides, ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxy ad
  • the chemically functionalized graphene sheets contain a chemical functional group selected from the group consisting of l0,l2-pentacosadiyn-l-ol, 1- pyrenebutyric acid N-hydroxysuccinimide ester, l-aminopyrene, derivatives thereof, and combinations thereof.
  • the process may further comprise a step of reducing the non-carbon content to less than 20% (preferably less than 5%) by weight using chemical, thermal, UV, or radiation-induced reduction means.
  • reducing the non-carbon content to less than 20% (preferably less than 5%) by weight using chemical, thermal, UV, or radiation-induced reduction means.
  • one may optionally subject the long or continuous fiber to a heat treatment at a temperature of typically 200-700°C to thermally reduce the non-carbon content.
  • the inter-plane spacing doo 2 is from 0.4 nm to 1.2 nm, the non- carbon element content is from 1% to 20%, or physical density from 1.7 to 2.15 g/cm .
  • the continuous or long fiber can have a cross-section that is circular, elliptical, rectangular, flat-shaped, or hollow.
  • the fiber preferably has a length from 1 cm to 10,000 meters, a cross-section having a width (or second largest dimension) from 1 pm to 10 mm, and a thickness (or smallest dimension) from 10 nm to 500 pm, and a width-to-thickness ratio from 1 to 10,000.
  • the long fiber has a width from 1 to 20 pm and a thickness from 100 nm to 100 pm.
  • the long fiber has a thermal conductivity from 200 to 1,600 W/mK or an electrical conductivity from 600 to 15,000 S/cm; preferably and typically having a thermal conductivity of at least 350 W/mK or an electrical conductivity no less than 1,000 S/cm; further preferably and typically having a thermal conductivity of at least 600 W/mK or an electrical conductivity no less than 2,500 S/cm; still further preferably having a thermal conductivity of at least 1,000 W/mK or an electrical conductivity no less than 5,000 S/cm; and most preferably having a thermal conductivity of at least 1,200 W/mK, or an electrical conductivity no less than 8,000 S/cm.
  • the long fiber contains a first graphene domain containing bonded graphene planes parallel to one another and having a first crystallographic c-axis, and a second graphene domain containing bonded graphene planes parallel to one another and having a second crystallographic c-axis wherein the first crystallographic c-axis and the second crystallographic c-axis are inclined with respect to each other at an angle less than 10 degrees.
  • the long fiber contains a combination of sp and sp electronic configurations.
  • the long fiber typically and preferably has a Young’s modulus from 20 GPa to 300 GPa (more typically from 30 GPa to 150 GPa), or a tensile strength from 1.0 GPa to 5.0 GPa (more typically from 1.2 GPa to 3.0 GPa).
  • the invented process may further comprise a step of incorporating the long fiber to produce a fiber yam or bundle. In certain embodiments, the process further comprises a step of incorporating a plurality of the invented long fibers to produce a fiber yam or bundle.
  • the present disclosure also provides a fiber yarn or bundle comprising at least a long fiber of present disclosure.
  • the yam or bundle can also contain other type of fibers, including polyacrylonitrile (PAN)-derived carbon fibers, pitch-derived carbon fibers, or a combination thereof, to form a hybrid yam or bundle.
  • PAN polyacrylonitrile
  • the disclosure also provides fiber yam or bundle comprising a plurality of presently invented long fibers.
  • FIG. 1 Schematic drawing illustrating the processes for producing conventional paper, mat, film, and membrane of simply aggregated graphite or graphene flakes/platelets. All processes begin with intercalation and/or oxidation treatment of graphitic materials (e.g. natural graphite particles).
  • graphitic materials e.g. natural graphite particles
  • FIG. 2(a) A SEM image of a graphite worm sample after thermal exfoliation of graphite
  • GICs intercalation compounds
  • graphite oxide powders
  • FIG. 2 (b) An SEM image of a cross-section of a flexible graphite foil, showing many graphite flakes with orientations not parallel to the flexible graphite foil surface and also showing many defects, kinked or folded flakes;
  • FIG. 2 (c) SEM images of an elongated section of prior art graphene fibers produced by solution spinning and liquid coagulation, showing many graphene sheets with orientations not parallel to the fiber axis direction and also showing many defects, pores, kinked or folded graphene sheets;
  • FIG. 2 (d) SEM images of another elongated section of prior art graphene fibers produced by solution spinning and liquid coagulation.
  • FIG. 3(a) A SEM image of a long graphene fiber produced from chemically functionalized GO sheets
  • FIG. 3(b) A SEM image of a cross-section of a conventional graphene paper/film prepared from discrete graphene sheets/platelets using a paper-making process (e.g. vacuum-assisted filtration).
  • the image shows many discrete graphene sheets being folded or interrupted (not integrated), with orientations not parallel to the film/paper surface and having many defects or imperfections;
  • FIG. 3(c) One plausible chemical linking mechanism (only 2 GO sheets are shown as an
  • a large number of GO sheets can be chemically linked together to form a long graphene fiber).
  • FIG. 4 Schematic diagram illustrating a process of producing multiple continuous graphene fibers from functionalized graphene sheets dispensed through multiple nozzles under the influence of a shear stress and high strain rate.
  • FIG. 5(a) Chemical functionalization of graphene sheets, Scheme 1.
  • FIG. 5(b) Chemical functionalization of graphene sheets, Scheme 2.
  • FIG. 5(c) An example to illustrate one mechanism with which neighboring chemically functionalized graphene sheets are chemically interconnected together.
  • FIG. 6 Tensile strength and Young’s modulus of three graphene fibers: one derived from highly oriented chemically functionalized graphene sheets, one derived from highly oriented graphene oxide sheets, and a conventional coagulation-based reduced graphene oxide fiber.
  • the present disclosure provides a graphene-based long fiber comprising chemically functionalized graphene sheets that are chemically bonded interconnected with one another having an inter-planar spacing doo2 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content (e.g. H, O, N, B, P, Cl, F, Br, I, S, etc.) of 0.1% to 47% by weight, wherein the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core-shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from
  • a non-carbon element content e.g. H, O, N, B, P, Cl, F, Br, I, S, etc.
  • This long fiber can be an essentially“continuous fiber” wound as a spool on a roller and having a length up to several kilometers (e.g. 10 km).
  • the graphene sheets are typically interconnected with one another via chemical bonding or reactions between the chemically active functional groups attached to respective adjacent functional groups.
  • the present disclosure also provides a process for producing a graphene -based continuous or long fiber from chemically functionalized graphene sheets.
  • the process comprises:
  • a liquid medium e.g. water or an organic solvent
  • the chemically functionalized graphene sheets contain chemical functional groups attached thereto (on graphene sheet surfaces and/or edges) and a non-carbon element content of 0.1% to 47% by weight;
  • dispersion onto a supporting substrate e.g. using casting, slot-die coating, comma coating, reverse-roll coating, ultrasonic spraying, or pressure air-assisted spraying, etc.
  • the dispensing and depositing procedure includes applying a mechanical shear stress to induce alignment of the chemically functionalized graphene sheets along the filament axis direction, and partially or completely removing the liquid medium from the filament to form a continuous or long fiber comprising aligned chemically functionally graphene sheets (e.g. the coating head can create a high shear stress between the dispensed graphene dispersion and the supporting substrate that undergoes a relative fast motion relative to the coating head); and
  • the long graphene fiber comprises chemically functionalized graphene sheets that are chemically bonded or interconnected with one another having an inter-planar spacing doo2 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content of 0.1% to 40% by weight and wherein the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core- shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from 1.5 to 2.2 g/cm 3 .
  • electromagnetic waves e.g. radio frequency waves, or microwaves
  • UV light e.g. ultraviolet light
  • high-energy radiation e.g. electron beam, Gamma ray, or X-ray
  • the functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core- shell structure, have no helically arranged graphene domains, and have
  • multiple filaments can be produced concurrently if we dispense and form multiple continuous filaments of functionalized graphene sheets onto a supporting substrate at the same time.
  • Step (a) includes dispersing chemically functionalized graphene sheets in a liquid medium, such as water or organic solvent.
  • a liquid medium such as water or organic solvent.
  • a graphite intercalation compound (GIC) or graphite oxide may be obtained by immersing powders or filaments of a starting graphitic material in an intercalating/ oxidizing liquid medium (e.g. a mixture of sulfuric acid, nitric acid, and potassium permanganate) in a reaction vessel.
  • the starting graphitic material may be selected from natural graphite, artificial graphite, mesophase carbon, mesophase pitch, mesocarbon microbead, soft carbon, hard carbon, coke, carbon fiber, carbon nanofiber, carbon nanotube, or a combination thereof.
  • the resulting slurry is a heterogeneous suspension and appears dark and opaque.
  • the oxidation of graphite proceeds at a reaction temperature for a sufficient length of time (4-120 hours at room temperature, 20-25°C), the reacting mass can eventually become a suspension that appears slightly green and yellowish, but remain opaque. If the degree of oxidation is sufficiently high (e.g.
  • each oxidized graphene plane (now a graphene oxide sheet or molecule) is surrounded by the molecules of the liquid medium, one obtains a GO gel.
  • a graphite particle (e.g. 100) is typically composed of multiple graphite crystallites or grains.
  • a graphite crystallite is made up of layer planes of hexagonal networks of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and are oriented or ordered so as to be substantially parallel and equidistant to one another in a particular crystallite.
  • These layers of hexagonal- structured carbon atoms commonly referred to as graphene layers or basal planes, are weakly bonded together in their thickness direction (crystallographic c-axis direction) by weak van der Waals forces and groups of these graphene layers are arranged in crystallites.
  • the graphite crystallite structure is usually characterized in terms of two axes or directions: the c-axis direction and the a-axis (or h-axis) direction.
  • the c- axis is the direction perpendicular to the basal planes.
  • the a- or h-axes are the directions parallel to the basal planes (perpendicular to the c-axis direction).
  • a highly ordered graphite particle can consist of crystallites of a considerable size, having a length of L a along the crystallographic a-axis direction, a width of L b along the crystallographic h-axis direction, and a thickness L c along the crystallographic c-axis direction.
  • the constituent graphene planes of a crystallite are highly aligned or oriented with respect to each other and, hence, these anisotropic structures give rise to many properties that are highly directional.
  • the thermal and electrical conductivity of a crystallite are of great magnitude along the plane directions ⁇ a- or h-axis directions), but relatively low in the perpendicular direction (c-axis).
  • different crystallites in a graphite particle are typically oriented in different directions and, hence, a particular property of a multi-crystallite graphite particle is the directional average value of all the constituent crystallites.
  • natural graphite can be treated so that the spacing between the graphene layers can be appreciably opened up so as to provide a marked expansion in the c-axis direction, and thus form an expanded graphite structure in which the laminar character of the carbon layers is substantially retained.
  • the process for manufacturing flexible graphite is well-known in the art.
  • flakes of natural graphite e.g. 100 in FIG. 1 are intercalated in an acid solution to produce graphite intercalation compounds (GICs, 102).
  • GICs graphite intercalation compounds
  • the exfoliated graphite flakes are vermiform in appearance and, hence, are commonly referred to as worms 104.
  • These worms of graphite flakes which have been greatly expanded can be formed without the use of a binder into cohesive or integrated sheets of expanded graphite, e.g. webs, papers, strips, tapes, foils, mats or the like (typically referred to as "flexible graphite" 106) having a typical density of about 0.04-2.0 g/cm for most applications.
  • the exfoliated graphite (or mass of graphite worms) is re compressed by using a calendaring or roll-pressing technique to obtain flexible graphite foils (106 in FIG. 1), which are typically 100-300 pm thick.
  • the exfoliated graphite worm may be impregnated with a resin and then compressed and cured to form a flexible graphite composite, which is normally of low strength as well.
  • the exfoliated graphite may be subjected to high-intensity mechanical shearing/separation treatments using a high-intensity air jet mill, high-intensity ball mill, or ultrasonic device to produce separated nano graphene platelets (NGPs) with all the graphene platelets thinner than 100 nm, mostly thinner than 10 nm, and, in many cases, being single-layer graphene (also illustrated as 112 in FIG. 1).
  • NGPs nano graphene platelets
  • An NGP is composed of a graphene sheet or a plurality of graphene sheets with each sheet being a two-dimensional, hexagonal structure of carbon atoms.
  • graphite worms tend to be separated into the so-called expanded graphite flakes (108 in FIG. 1) having a thickness > 100 nm.
  • expanded graphite flakes can be formed into graphite paper or mat 106 using a paper- or mat- making process.
  • This expanded graphite paper or mat 106 is just a simple aggregate or stack of discrete flakes having defects, interruptions, and mis-orientations between these discrete flakes.
  • the NGP is described as having a length (the largest dimension), a width (the second largest dimension), and a thickness.
  • the thickness is the smallest dimension, which is no greater than 100 nm, preferably smaller than 10 nm and most preferably 0.34 nm - 1.7 nm in the present application.
  • the length and width are referred to as diameter. In the presently defined NGPs, both the length and width can be smaller than 1 pm, but can be larger than 200 pm.
  • a mass of multiple NGPs may be readily dispersed in water or a solvent and then made into a graphene paper (114 in FIG. 1) using a paper-making process.
  • Many discrete graphene sheets are folded or interrupted (not integrated), most of platelet orientations being not parallel to the paper surface.
  • the existence of many defects or imperfections leads to poor electrical and thermal conductivity in both the in-plane and the through -plane (thickness-) directions.
  • Fluorinated graphene or graphene fluoride is herein used as an example of the halogenated graphene material group.
  • fluorination of pre- synthesized graphene This approach entails treating graphene prepared by mechanical exfoliation or by CVD growth with fluorinating agent such as XeF 2 , or F-based plasmas;
  • Exfoliation of multilayered graphite fluorides Both mechanical exfoliation and liquid phase exfoliation of graphite fluoride can be readily accomplished [F. Karlicky, et al.“ Halogenated Graphenes: Rapidly Growing Family of Graphene Derivatives” ACS Nano, 2013, 7 (8), pp 6434-6464].
  • the process of liquid phase exfoliation includes ultra-sonic treatment of a graphite fluoride in a liquid medium to produce graphene fluoride sheets dispersed in the liquid medium.
  • the resulting dispersion can be directly made into a sheet of paper or a roll of paper.
  • the nitrogenation of graphene can be conducted by exposing a graphene material, such as graphene oxide, to ammonia at high temperatures (200-400°C). Nitrogenated graphene could also be formed at lower temperatures by a hydrothermal method; e.g. by sealing GO and ammonia in an autoclave and then increased the temperature to l50-250°C. Other methods to synthesize nitrogen doped graphene include nitrogen plasma treatment on graphene, arc- discharge between graphite electrodes in the presence of ammonia, ammonolysis of graphene oxide under CVD conditions, and hydrothermal treatment of graphene oxide and urea at different temperatures.
  • a graphene material such as graphene oxide
  • Nitrogenated graphene could also be formed at lower temperatures by a hydrothermal method; e.g. by sealing GO and ammonia in an autoclave and then increased the temperature to l50-250°C.
  • Other methods to synthesize nitrogen doped graphene include nitrogen plasma treatment on graph
  • NGPs or graphene materials include discrete sheets/platelets of single-layer and multi-layer (typically less than 10 layers, the few-layer graphene) pristine graphene, graphene oxide, reduced graphene oxide (RGO), graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, doped graphene (e.g. doped by B or N).
  • Pristine graphene has essentially 0% oxygen.
  • RGO typically has an oxygen content of 0.00l%-5% by weight.
  • Graphene oxide (including RGO) can have 0.00l%-50% by weight of oxygen.
  • all the graphene materials have 0.00l%-50% by weight of non-carbon elements (e.g. O, H, N, B, F, Cl, Br, I, etc.). These materials are herein referred to as non-pristine graphene materials.
  • non-pristine graphene materials e.g. O, H, N, B, F, Cl, Br, I, etc.
  • the presently invented graphene fiber can contain pristine or non-pristine graphene and the invented method allows for this flexibility.
  • Pristine graphene is one of the most chemically inert materials because high energy barriers need to be overcome due to the rigid planar structure and remarkable interlayer conjugation.
  • diazonium chemistry and photochemistry various functional groups have been grafted onto graphene.
  • stirring-assisted solution reaction may be tedious.
  • photochemistry either a focused laser spot may be used to generate a sufficiently high intensity, resulting in a localized functionalization of graphene sheets.
  • a heat-initiated chemical reaction can be used to functionalize pristine graphene prepared by chemical vapor deposition (CVD) or liquid phase exfoliation.
  • the most attractive organic species for the reaction with sp2 carbons of graphene are organic free radicals and dienophiles. Usually both are intermediate reactive components that are produced under certain conditions in the presence of graphene.
  • a diazonium salt Upon heating of a diazonium salt, a highly reactive free radical is produced, which attacks the sp2 carbon atoms of graphene, thereby forming a covalent bond.
  • This reaction can be used to decorate graphene with nitrophenyls.
  • the strong covalent binding of the nitrobenzyl group on graphene may be detected by X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the Nls XPS spectrum of the functionalized graphene normally exhibits two peaks at 406 and 400 eV that correspond to the nitrogen of N0 2 and the partially reduced nitrogen of the product, respectively.
  • the reactions with diazonium salts have been applied to the functionalization of chemically or thermally converted graphene, single graphene sheets obtained by micromechanical cleavage from bulk graphite, and epitaxial graphene.
  • Hydroxylated aryl groups can be grafted covalently on graphene by the diazonium addition reaction.
  • the ratio between carbon atoms with sp2 and sp3 hybridization in the graphitic lattice is an indication of the degree of oxidation or a covalent functionalization reaction. This ratio may be estimated using Raman spectroscopy as the ID/IG ratio, where ID and IG are the intensities of the peaks at— 1350 and 1580 cm -1 , which correspond to the number of sp3 and sp2 C atoms, respectively.
  • Graphene is often defined as a pristine two-dimensional sp2 hybridized carbon sheet; as such the coexistence of sp3 carbons in the lattice are inherently classified as defects, where these defects can be on the basal edges or inside defects in the plane.
  • the ID/IG ratio is increased from 1.7 to ⁇ 2 after functionalization by diazonium addition.
  • An alternative free radical addition method includes the reaction of benzoyl peroxide with graphene sheets. Graphene sheets may be deposited on a silicon substrate and immersed in a benzoyl peroxide/toluene solution. The reaction is then initiated photochemically by focusing an Ar-ion laser beam onto the graphene sheets in the solution.
  • the attachment of the phenyl groups is directly indicated by the appearance of a strong D band at 1343 cm -1 .
  • the appearance of this D band is due to the formation of sp3 carbon atoms in the basal plane of graphene by covalent attachment of phenyl groups.
  • a type of metalized graphene may be used in the reaction with 1- iododecane to produce dodecylated graphene (Scheme 1, FIG. 5(A)).
  • the FT-IR spectra can be used to confirm presence of C-H stretching bands at 2800-3000 cm 1 associated with the dodecyl groups.
  • TGA may indicate a weight loss of 15%, which corresponds to about one dodecyl group per 78 graphite carbon atoms.
  • the resulting dodecylated graphene is soluble in chloroform, benzene, and 1,2, 4-trichlorobenzene. Additionally, its solubility in water can be achieved by the reaction of potassium graphene with 5-bromovaleric acid and subsequent reaction with amine- terminated PEG (see Scheme 1).
  • Top-down approaches may be used to prepare chemically-functionalized graphene with an objective to make them dispersible in a selected liquid medium.
  • graphene oxide (GO) nanosheets having ample oxygen functionalities in the basal plane and along the edges may be selectively targeted for the chemical functionalization.
  • ODA octadecylamine
  • rGO reduced graphene oxide
  • oxygen functionalities in the basal plane of GO can be selected to tether the octadecylamine via covalent, charge-induced electrostatic and hydrogen linkages between the amino group of ODA and epoxy, carboxylic and hydroxyl functionalities of GO, respectively.
  • the chemical and structural features of products may be examined by FTIR, 13 C NMR, XPS, XRD and HRTEM.
  • rGO can be covalently functionalized with imidazolium ionic liquids having bis(salicylato)borate, oleate and hexafluorophosphate anions.
  • Chemical functionalized graphene may also be obtained by the reaction of the residual epoxide and carboxyl functional groups on the hydrazine-reduced graphene sheets with hydroquinone.
  • a simple method often used for the functionalization of graphene is based on reactions of the carboxyl groups, present in GO and located at the edges of graphene sheets, with various amines or alcohols.
  • Dodecylamide- functionalized graphene is dispersible in dichlormethane, carbon tetrachloride (CCl 4 ) and tetrahydrofuran (THF).
  • CCl 4 carbon tetrachloride
  • THF tetrahydrofuran
  • a similar approach via an acyl chloride intermediate may also be used for the modification of graphite oxide with octadecylamine (ODA).
  • graphene oxide sheets are immersed in a solution of 10,12- pentacosadiyn-l-ol [PCO, CH (CH 2 ) I I CoC-CoC(CH ) CH 2 OH] to form a graphene dispersion.
  • the dispersion is then coated on a PET substrate under a high shear stress and high shear rate condition (shear rate from 0.1 to 10 5 sec 1 , preferably from 10 2 to 10 4 sec 1 ) to form a filament comprising highly oriented GO sheets lightly coated with PCO.
  • a high shear stress and high shear rate condition shear rate from 0.1 to 10 5 sec 1 , preferably from 10 2 to 10 4 sec 1
  • the filament after drying, may be exposed to UV light to provide a fiber of PCO-GO sheets in which the diacetylene groups of PCO have reacted by 1, 4-addition polymerization. Subsequently, the fiber may be immersed in hydroiodic acid (HI) to reduce the PCO-GO sheets into graphene-PCO sheets.
  • HI hydroiodic acid
  • the fiber of graphene-PCO sheets is immersed successively into l-pyrenebutyric acid N-hydroxysuccinimide ester (PSE) and l-aminopyrene (AP) solutions, thereby providing a fiber of interconnected graphene sheet in which the PSE and AP have bonded through p-p interactions with neighboring graphene sheets and reacted to provide PSE- AP covalent bonds.
  • PSE l-pyrenebutyric acid N-hydroxysuccinimide ester
  • AP l-aminopyrene
  • Step (b) includes dispensing and depositing at least a continuous or long filament of the graphene dispersion onto a supporting substrate. This can be accomplished by using casting, slot- die coating, comma coating, reverse-roll coating, ultrasonic spraying, or pressure air-assisted spraying, etc.).
  • the dispensing and depositing procedure preferably includes using mechanical shear stress to align or orient the chemically functionalized graphene sheets along the filament axis direction.
  • the coating head can be operated to create a high shear stress and high strain rate between the dispensed graphene dispersion and the supporting substrate that undergoes a relative motion relative to the coating head.
  • This mechanical stress/strain condition enables all the constituent graphene sheets or graphene domains to be aligned along the graphene fiber axis direction and be substantially parallel to one another. More significantly, the graphene sheets are closely packed to facilitate chemical reactions or cross-linking (interconnection) between graphene sheets. In other words, not only the graphene planes in a particular domain are parallel to one another, they are also parallel to the graphene planes in the adjacent domain. The crystallographic c-axes of these two sets of graphene planes are pointing along substantially identical directions. As such, the domains do not follow a helical or twisting pattern.
  • the continuous graphene fiber contains a first graphene domain containing bonded graphene sheets parallel to one another and having a first crystallographic c-axis, and a second graphene domain containing bonded graphene sheets parallel to one another and having a second crystallographic c-axis wherein the first
  • crystallographic c-axis and the second crystallographic c-axis are inclined with respect to each other at an angle less than 10 degrees (mostly less than 5% and even more often less than 1 degree).
  • multiple dispensing devices or one dispensing device with multiple nozzles may be used to dispense multiple filaments of graphene sheets onto a moving substrate in a continuous manner.
  • a feeder roller provides a solid substrate (e.g. plastic film) that moves from the left side to the right side of FIG. 4 and is collected on a take-up roller.
  • a drying/heating zone may be implemented to remove most of the liquid component (e.g. water or organic solvent) from the filaments prior to being collected on the winding roller. Multiple filaments may be laid onto the substrate concurrently.
  • Step (c) entails using heat, electromagnetic waves (e.g. radio frequency waves or microwaves), UV light, high-energy radiation (e.g. electron beam, Gamma ray, or X-ray), or a combination thereof to induce chemical reactions or chemical bonding between chemical functional groups attached to adjacent chemically functionalized graphene sheets to form the long graphene fiber.
  • the chemical functional groups and the chemical reaction conditions (including graphene sheet orientation, close-packing, etc.) enable the formation of a long graphene fiber comprising chemically functionalized graphene sheets that are chemically bonded with one another having an inter-planar spacing doo2 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content of 0.1% to 40% by weight.
  • functionalized graphene sheets are substantially parallel to one another and parallel to the fiber axis direction and the fiber contains no core- shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from 1.5 to 2.2 g/cm .
  • the disclosure also provides a process for producing a graphene -based long fiber from initially un-functionalized graphene sheets.
  • the process comprises:
  • dispersion onto a supporting substrate wherein the dispensing and depositing procedure includes mechanical shear stress-induced alignment of the graphene sheets along a filament axis direction, and partially or completely removing the fluid medium from the filament to form a continuous or long fiber comprising aligned graphene sheets;
  • graphene sheets are not functionalized initially. They are functionalized after the graphene sheets are made into a fiber.
  • the chemically functionalized graphene sheets in the long fiber contain a chemical functional group selected from the group consisting of alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, carboxylic group, amine group, sulfonate group (— S0 3 H), aldehydic group, quinoidal, fluorocarbon, derivatives thereof, and combinations thereof.
  • the chemically functionalized graphene sheets contain a chemical functional group selected from an oxygenated group consisting of hydroxyl, peroxide, ether, keto, aldehyde, and combinations thereof.
  • the chemically functionalized graphene sheets contain a chemical functional group selected from the group consisting of -S0 3 H, -COOH, -NH 2 , -OH, - R'CHOH, -CHO, -CN, -COC1, halide, -COSH, -SH, -COOR', -SR', -SiR' 3 , -Si(-OR'-) y R' 3 -y, - Si(— O— SiR' 2 — )OR', -R", Li, AlR' 2 , Hg— X, TlZ 2 and Mg— X; wherein y is an integer equal to or less than 3, R' is hydrogen, alkyl, aryl, cycloalkyl, or aralkyl, cycloaryl, or poly (alky lether), R" is fluoroalkyl, fluoroaryl, fluorocycloalkyl, fluoroaralkyl or
  • the chemically functionalized graphene sheets contain a chemical functional group selected from the group consisting of amidoamines, polyamides, aliphatic amines, modified aliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides, ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxy adduct, phenolic hardener, non-brominated curing agent, non-amine curatives, derivatives thereof, and combinations thereof.
  • a chemical functional group selected from the group consisting of amidoamines, polyamides, aliphatic amines, modified aliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides, ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxy ad
  • the chemically functionalized graphene sheets contain a chemical functional group selected from the group consisting of l0,l2-pentacosadiyn-l-ol, 1- pyrenebutyric acid N-hydroxysuccinimide ester, l-aminopyrene, derivatives thereof, and combinations thereof.
  • the process may further comprise a step (d) of compressing the graphene fibers after formation to increase the physical density of the fiber and further align the constituent graphene sheets.
  • the process may further comprise a step of reducing the non-carbon content to less than 20% (preferably less than 5%) by weight using chemical, thermal, UV, or radiation-induced reduction means. For instance, one may optionally subject the long or continuous fiber to a heat treatment at a temperature typically 200-700°C to thermally reduce the non-carbon content.
  • the presently invented graphene-based fiber is an integrated graphene phase composed of chemically interconnected graphene sheets that are essentially oriented parallel to one another.
  • the graphene sheets are also closely packed to exhibit a high physical density.
  • the yam-like graphene fibers prepared by the prior art processes are a simple, un-bonded aggregate/stack of multiple discrete platelets or sheets of graphene, GO, or RGO that are just mechanically fastened together.
  • the present graphene fiber of the present disclosure is a fully integrated monolith containing essentially no discrete sheets or platelets. All the graphene sheets are chemically interconnected.
  • the graphene-based long or continuous fiber Due to these unique chemical compositions (including non-carbon content), morphology, crystal stmcture (including inter-graphene spacing), and micro structural features (e.g. defects, chemical bonding and no gap between graphene sheets, nearly perfectly aligned graphene sheets, and no interruptions in graphene planes), the graphene-based long or continuous fiber has a unique combination of outstanding thermal conductivity, electrical conductivity, tensile strength, and Young’s modulus. No prior art continuous fiber of any material type even comes close to these combined properties. Again, specifically and most significantly, these chemically functionalized graphene sheets are capable of chemically bonding, linking, or merging with one another and becoming integrated into highly parallel and interconnected graphene sheets (e.g. FIG. 3(a)).
  • the produced long or continuous fiber has a thermal conductivity from 200 to 1,600 W/mK, or an electrical conductivity from 600 to 15,000 S/cm; more preferably and typically having a thermal conductivity of at least 350 W/mK or an electrical conductivity no less than 1,000 S/cm; further more preferably and typically having a thermal conductivity of at least 600 W/mK or an electrical conductivity no less than 2,500 S/cm; still further preferably and typically having a thermal conductivity of at least 1,000 W/mK or an electrical conductivity no less than 5,000 S/cm; and most preferably having a thermal conductivity of at least 1,200 W/mK, or an electrical conductivity no less than 8,000 S/cm.
  • the long or continuous fiber typically and preferably has a Young’s modulus from 20 GPa to 300 GPa (more typically from 30 GPa to 150 GPa), or a tensile strength from 1.0 GPa to 5.0 GPa (more typically from 1.2 GPa to 3.0 GPa).
  • Example 1 Preparation of single-layer graphene sheets from mesocarbon microbeads (MCMBs)
  • MCMBs Mesocarbon microbeads
  • MCMB 10 grams were intercalated with an acid solution (sulfuric acid, nitric acid, and potassium permanganate at a ratio of 4:1:0.05) for 48-96 hours. Upon completion of the reaction, the mixture was poured into deionized water and filtered. The intercalated MCMBs were repeatedly washed in a 5% solution of HC1 to remove most of the sulfate ions. The sample was then washed repeatedly with deionized water until the pH of the filtrate was no less than 4.5.
  • the slurry was then subjected ultrasonication for 10-100 minutes to produce GO suspensions.
  • TEM and atomic force microscopic studies indicate that most of the GO sheets were single-layer graphene when the oxidation treatment exceeded 72 hours, and 2- or 3-layer graphene when the oxidation time was from 48 to 72 hours.
  • the GO sheets contain oxygen proportion of approximately 35%-47% by weight for oxidation treatment times of 48-96 hours.
  • GO sheets were suspended in water.
  • the GO suspension was formed into small filaments on a glass surface.
  • the pristine graphene sheets were immersed into a 10 mM acetone solution of BPO for 30 min and were then taken out drying naturally in air.
  • the heat-initiated chemical reaction to functionalize graphene sheets was conducted at 80°C in a high-pressure stainless steel container filled with pure nitrogen. Subsequently, the samples were rinsed thoroughly in acetone to remove BPO residues for subsequent Raman characterization. As the reaction time increased, the characteristic disorder-induced D band around 1330 cm -1 emerged and gradually became the most prominent feature of the Raman spectra.
  • the D-band is originated from the A lg mode breathing vibrations of six-membered sp carbon rings, and becomes Raman active after neighboring sp carbon atoms are converted to sp hybridization.
  • the functionalized graphene sheets were re-dispersed in water to produce a graphene dispersion.
  • the dispersion was then made into multiple filaments.
  • Graphite oxide was prepared by oxidation of graphite flakes with an oxidizer liquid consisting of sulfuric acid, sodium nitrate, and potassium permanganate at a ratio of 4:1:0.05 at 30°C.
  • an oxidizer liquid consisting of sulfuric acid, sodium nitrate, and potassium permanganate at a ratio of 4:1:0.05 at 30°C.
  • the reacting mass was rinsed with water 3 times to adjust the pH value to at least 3.0.
  • a final amount of water was then added to prepare a series of GO-water suspensions. We observed that GO sheets form a liquid crystal phase when GO sheets occupy a weight fraction > 3% and typically from 5% to 15%.
  • the fibers after drying, were exposed to UV light to provide fibers of PCO-GO sheets in which the diacetylene groups of PCO react by 1, 4-addition polymerization. Subsequently, the fibers were immersed in hydroiodic acid (HI) to reduce the PCO-GO sheets in the fiber into graphene-PCO sheets.
  • HI hydroiodic acid
  • the fibers of graphene-PCO sheets are immersed successively into l-pyrenebutyric acid N-hydroxysuccinimide ester (PSE) and l-aminopyrene (AP) solutions, thereby providing fibers of interconnected rGO sheets in which the PSE and AP have bonded through p-p interactions with neighboring rGO sheets and react to provide PSE-AP covalent bonds.
  • PSE l-pyrenebutyric acid N-hydroxysuccinimide ester
  • AP l-aminopyrene
  • HEG highly exfoliated graphite
  • FHEG fluorinated highly exfoliated graphite
  • Pre-cooled Teflon reactor was filled with 20-30 mL of liquid pre-cooled ClF 3 , the reactor was closed and cooled to liquid nitrogen temperature. Then, no more than 1 g of HEG was put in a container with holes for ClF 3 gas to access and situated inside the reactor. In 7-10 days a gray-beige product with approximate formula C 2 F was formed.
  • FHEG FHEG
  • an organic solvent methanol, ethanol, 1 -propanol, 2-propanol, 1 -butanol, / ⁇ ? /7 -butanol, isoamyl alcohol
  • an ultrasound treatment 280 W
  • Five minutes of sonication was enough to obtain a relatively homogenous dispersion, but longer sonication times ensured better stability.
  • the dispersion Upon extrusion to form filaments on a glass surface with the solvent removed, the dispersion became brownish filaments formed on the glass surface.
  • Graphene oxide (GO), synthesized in Example 2 was finely ground with different proportions of urea and the pelletized mixture heated in a microwave reactor (900 W) for 30 s. The product was washed several times with deionized water and vacuum dried. In this method graphene oxide gets simultaneously reduced and doped with nitrogen.
  • the products obtained with graphene/urea mass ratios of 1/0.5, 1/1 and 1/2 are designated as NGO-l, NGO-2 and NGO-3 respectively and the nitrogen contents of these samples were 14.7, 18.2 and 17.5 wt% respectively as found by elemental analysis.
  • These nitrogenated graphene sheets remain dispersible in water.
  • the resulting suspensions were then extruded and made into filaments. Upon drying, the resulting nitrogenated graphene fibers exhibit physical densities from 1.75 to 2.05 g/cm 3 .
  • Example 6 Chemical functionalization of graphene fluoride and nitrogenated graphene foam, and carbon nanofiber paper
  • Specimens of graphene fluoride fibers and nitrogenated graphene fibers prepared earlier were subjected to functionalization by bringing these specimens in chemical contact with chemical compounds such as carboxylic acids, azide compound (2-azidoethanol), alkyl silane, diethylenetriamine (DETA), and chemical species containing hydroxyl group, carboxyl group, amine group, and sulfonate group (— S0 3 H) in a liquid or solution form.
  • chemical compounds such as carboxylic acids, azide compound (2-azidoethanol), alkyl silane, diethylenetriamine (DETA), and chemical species containing hydroxyl group, carboxyl group, amine group, and sulfonate group (— S0 3 H) in a liquid or solution form.
  • FIG. 3(a) A close scrutiny and comparison of FIG. 3(a) indicates that the graphene planes in a graphene long fiber are substantially oriented parallel to one another; but this is not the case for coagulation-derived graphene fibers (FIG. 2(c)).
  • the inclination angles between two identifiable layers in the graphene fiber are mostly less than 5 degrees.
  • the presently invented long or continuous fibers have a thermal conductivity typically from 200 to 1,600 W/mK.
  • the electrical conductivity is typically from 600 to 15,000 S/cm.
  • These fibers have a thermal conductivity more typically from 350 to 1,500 W/mK or an electrical conductivity more typically from 1,000 to 12,000 S/cm.
  • FIG. 6 This specimen of a graphene fiber produced from chemically functionalized graphene sheets exhibits a tensile strength of 2.26 GPa and a Young’s modulus of 31 GPa.
  • Most of the presently invented graphene fibers have a Young’s modulus from 20 GPa to 300 GPa (more typically from 30 GPa to 150 GPa), or a tensile strength from 1.0 GPa to 5.0 GPa (more typically from 1.2 GPa to 3.0 GPa).

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Abstract

L'invention concerne une fibre longue à base de graphène comprenant des feuilles de graphène chimiquement fonctionnalisées qui sont liées chimiquement les unes aux autres ayant un espacement inter-planaire d002 de 0,36 nm à 1,5 nm tel que déterminé par diffraction des rayons X et une teneur en élément non carboné de 0,1 % à 40 % en poids, les feuilles de graphène fonctionnalisées étant sensiblement parallèles les unes aux autres et parallèles à la direction de l'axe des fibres et la fibre ne contenant pas de structure cœur-écorce, n'ayant pas de domaines de graphène disposés en hélice, et ont une longueur non inférieure à 0,5 cm et une densité physique de 1,5 à 2,2 g/cm3. La fibre de graphène a typiquement une conductivité thermique de 300 à 1 600 W/mK, une conductivité électrique de 600 à 15 000 S/cm, ou une résistance à la traction supérieure à 1,0 GPa. L'invention concerne également un procédé de production d'une fibre continue ou longue à base de graphène.
PCT/US2019/032165 2018-05-14 2019-05-14 Fibres de graphène continues à partir de feuilles de graphène fonctionnalisées WO2019222175A1 (fr)

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Citations (5)

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Publication number Priority date Publication date Assignee Title
US20140308517A1 (en) * 2013-04-15 2014-10-16 Aruna Zhamu Continuous graphitic fibers from living graphene molecules
US20150038041A1 (en) * 2013-08-05 2015-02-05 Aruna Zhamu Fabric of continuous graphitic fiber yarns from living graphene molecules
US20150064463A1 (en) * 2013-09-02 2015-03-05 Enerage Inc. Graphene fiber and method of manufacturing the same
US20170225233A1 (en) * 2016-02-09 2017-08-10 Aruna Zhamu Chemical-free production of graphene-reinforced inorganic matrix composites
WO2018004476A1 (fr) * 2016-06-27 2018-01-04 Sabanci Üniversitesi Fibres à base de graphène et leur procédé de fabrication

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140308517A1 (en) * 2013-04-15 2014-10-16 Aruna Zhamu Continuous graphitic fibers from living graphene molecules
US20150038041A1 (en) * 2013-08-05 2015-02-05 Aruna Zhamu Fabric of continuous graphitic fiber yarns from living graphene molecules
US20150064463A1 (en) * 2013-09-02 2015-03-05 Enerage Inc. Graphene fiber and method of manufacturing the same
US20170225233A1 (en) * 2016-02-09 2017-08-10 Aruna Zhamu Chemical-free production of graphene-reinforced inorganic matrix composites
WO2018004476A1 (fr) * 2016-06-27 2018-01-04 Sabanci Üniversitesi Fibres à base de graphène et leur procédé de fabrication

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