WO2019182652A1 - Appareil pour la production au graphène d'articles polymères métallisés - Google Patents

Appareil pour la production au graphène d'articles polymères métallisés Download PDF

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Publication number
WO2019182652A1
WO2019182652A1 PCT/US2018/061421 US2018061421W WO2019182652A1 WO 2019182652 A1 WO2019182652 A1 WO 2019182652A1 US 2018061421 W US2018061421 W US 2018061421W WO 2019182652 A1 WO2019182652 A1 WO 2019182652A1
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WIPO (PCT)
Prior art keywords
graphene
polymer component
polymer
layer
sheets
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Application number
PCT/US2018/061421
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English (en)
Inventor
Yi-Jun Lin
Shaio-Yen Lee
Yao-De Jhong
Aruna Zhamu
Bor Z. Jang
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Nanotek Instruments, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from US15/924,971 external-priority patent/US20190283378A1/en
Priority claimed from US15/924,957 external-priority patent/US20190283377A1/en
Application filed by Nanotek Instruments, Inc. filed Critical Nanotek Instruments, Inc.
Publication of WO2019182652A1 publication Critical patent/WO2019182652A1/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
    • C01B32/198—Graphene oxide
    • 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
    • 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
    • C01B32/184—Preparation
    • C01B32/19—Preparation by exfoliation
    • C01B32/192—Preparation by exfoliation starting from graphitic oxides
    • 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

Definitions

  • the present disclosure relates generally to the field of metallization of polymer component surfaces and, more particularly, to a graphene-mediated metal-plated polymer article and a process and required apparatus for producing same.
  • Metallized plastics are commonly used for decorative purposes.
  • the surfaces of plastics such as acrylonitrile-butadiene-styrene (ABS) and ABS-Poiycarbonate blends, are metallized for use in sanitary fittings, automobile accessories, furniture, hardware, jewelries, and buttons/knobs. These articles of manufacture may be metallized to impart an attractive appearance to the article surfaces.
  • ABS acrylonitrile-butadiene-styrene
  • ABS-Poiycarbonate blends are metallized for use in sanitary fittings, automobile accessories, furniture, hardware, jewelries, and buttons/knobs. These articles of manufacture may be metallized to impart an attractive appearance to the article surfaces.
  • plastics, rubbers, and polymer matrix composites can also be metallized for functional purposes.
  • metallization of plasties-based electronic components may be carried out for the purpose of shielding against electromagnetic interference (EMI).
  • EMI electromagnetic interference
  • the surface properties of polymeric components can be altered in a controlled manner through metallic coating.
  • Articles made from an electrically nonconduc ive polymer e.g. plastic rubber, polymer matrix composite, etc.
  • an electrically nonconduc ive polymer e.g. plastic rubber, polymer matrix composite, etc.
  • the article is first cleaned and etched, then treated with a noble metal (e.g palladium) and finally metallized in a metallizing solution.
  • the etching step typically involves the use of chromic acid or chromosulfuric acid.
  • the etching step serves to make the surface of the article receptive to the subsequent metallization through improved surface wettability by the respective solutions in the subsequent treatment steps and to make the ultimately deposited metal being well-adhered to the polymer surface.
  • the surface of a polymer article is etched using chromosulfuric acid to form surface microcaverns in which metal is deposited and adhered.
  • the polymer component surface is activated by means of an activating agent (or activator), typically comprising a noble metal, and then metallized using electroless plating. Subsequently, a thicker metal layer can be deposited eiectrolytically.
  • Chromosulfuric acid-based etching solutions are toxic and should therefore be replaced where possible.
  • the etching solutions based on chromosulfuric acid may be replaced with those comprising permanganate salts.
  • permanganates in an alkaline medium for metallization of circuit boards as a carrier of electronic circuits has long been established. Since the hexavalent state (manganate) which arises in the oxidation is water-soluble and has sufficient stability under alkaline conditions, the manganate, similarly to bivalent chromium, can be oxidized eiectrolytically back to the original oxidizing agent, in this case the permanganate.
  • WO 2009/023628 A2 proposes the use of strongly acidic solutions comprising an alkali metal permanganate salt.
  • the solution contains about 20 g/1 alkali metal permanganate salt in 40-85% by weight phosphoric acid.
  • Such solutions form colloidal manganese(IV) species which are difficult to remove. Further, it is also difficult for colloids to for a coating of adequate quality.
  • WO 2009/023628 A2 proposes the use of manganese(VII) sources which do not contain any alkali metal or alkaline earth metal ions. However, the preparation of such manganese(VII) sources is costly and inconvenient.
  • the polymer component surface must be activated by means of an activating agent, which typically comprises a noble metal (e.g. palladium).
  • an activating agent typically comprises a noble metal (e.g. palladium).
  • the noble metals are known to be rare and expensive.
  • the chemically etched plastic surface is treated with a metal salt solution, containing cobalt salt, silver salt, tin salt, or lead salt.
  • the activated plastic surface must be further treated with a sulfide solution. The entire process is slow, tedious, and expensive.
  • the present disclosure provides a surface-metalized polymer article comprising a polymer component having a surface, a first layer composed of multiple graphene sheets and a conductive filler coated on the polymer component surface, and a second layer of a plated metal deposited on this first layer, wherein the multiple graphene sheets contain single-layer or few- layer graphene sheets selected from a pristine graphene material having essentially zero % of non-carbon elements, or a non-pristine graphene material having 0.001% to 25% by weight of non-carbon elements wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, doped graphene, chemically
  • the multiple graphene sheets and the conductive filler are bonded to the polymer component surface with or without an adhesive resin and the first layer has a thickness from 0.34 nm to 30 pm.
  • the present disclosure also provides an apparatus that can be used to produce the surface- metallized article.
  • the apparatus for manufacturing a surface-metalized polymer article may comprise: (a) a graphene deposition chamber (e.g. a graphene dispersion bath) that
  • a graphene dispersion comprising multiple graphene sheets and an optional conductive filler dispersed in a first liquid medium and an optional adhesive resin dissolved in the first liquid medium, wherein the graphene deposition chamber is operated to deposit the graphene sheets and optional conductive filler to a surface of at least a polymer component for forming at least a graphene-coated polymer component; and (b) a metallization chamber (e.g.
  • the multiple graphene sheets contain single-layer or few-layer graphene sheets selected from a pristine graphene material having essentially zero % of non-carbon elements, or a non-pristine graphene material having 0.001% to 25% by weight of non-carbon elements wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, doped graphene, chemically functionalized graphene, or a combination thereof.
  • the apparatus may further comprise a movable carrier for carrying the at least a polymer component and bringing the at least a polymer component in contact with the graphene dispersion (e.g. for dipping the at least a polymer component into the graphene dispersion bath and then retreating the at least one polymer component from this bath) for producing the at least a graphene-coated polymer component and/or bringing the at least a graphene-coated polymer component in contact with the plating solution (e.g.
  • the apparatus may further comprise a drying, heating, or curing provision in a working relation with the graphene deposition chamber (e.g. above the graphene dispersion bath) for partially or completely removing the first liquid medium from the at least a graphene-coated polymer component and/or for polymerizing or curing the optional adhesive resin for producing the at least a graphene-coated polymer component containing multiple graphene sheets that are bonded to the surface of the at least a polymer component.
  • a drying, heating, or curing provision in a working relation with the graphene deposition chamber (e.g. above the graphene dispersion bath) for partially or completely removing the first liquid medium from the at least a graphene-coated polymer component and/or for polymerizing or curing the optional adhesive resin for producing the at least a graphene-coated polymer component containing multiple graphene sheets that are bonded to the surface of the at least a polymer component.
  • the plating solution may contain a chemical plating solution, an electrochemical plating solution, or an electrolytical solution.
  • the plating solution contains a chemical plating solution comprising a metal salt dissolved in water or an organic solvent.
  • the conductive filler is selected from metal nanowires, carbon fibers, carbon nanofibers, carbon-coated fibers, conductive polymer fibers, nanofibers or nanowires of Sn0 2 , Zn0 2 , ln 2 0 3 , or indium-tin oxide (ITO), a conductive polymer not in a fiber form, or a combination thereof.
  • the metal nanowires are preferably selected from nanowires of silver (Ag), gold (Au), copper (Cu), platinum (Pt), zinc (Zn), cadmium (Cd), cobalt (Co), molybdenum (Mo), aluminum (Al), or a combination thereof.
  • the conductive polymer is preferably selected from the group consisting of polydiacetylene, polyacetylene (PAc), polypyrrole (PPy), polyaniline (PAni), polythiophene (PTh), polyisothionaphthene (PITN), polyheteroarylenvinylene (PArV), in which the heteroarylene group can be the thiophene, furan or pyrrole, poly-p-phenylene (PpP), polyphthalocyanine (PPhc) and the like, and their derivatives, and combinations thereof.
  • the chemical functional group is selected from from alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, amine group, sulfonate group (— S0 3 H), aldehydic group, quinoidal, fluorocarbon, or a combination thereof.
  • the functional group is selected from the group consisting of hydroxyl, peroxide, ether, keto, and aldehyde.
  • the functionalizing agent contains a 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(-0- 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(alkylether), R" is fluoroalkyl, fluoroaryl, fluorocycloalkyl, fluoroaralkyl or
  • the functional group may be 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, and combinations thereof.
  • the surface-metalized polymer article may be selected from a faucet, a shower head, a tubing, a pipe, a connector, an adaptor, a sink (e.g. kitchen or bathroom sink), a bathtub cover, a spout, a sink cover, a bathroom accessory, or a kitchen accessory.
  • a sink e.g. kitchen or bathroom sink
  • a bathtub cover e.g. a spout, a sink cover, a bathroom accessory, or a kitchen accessory.
  • the first layer contains an adhesive resin that chemically bonds the graphene sheets and the conductive filler to the polymer component surface.
  • the graphene sheets contain a non-pristine graphene material having a content of non-carbon elements from 0.01% to 20% by weight and the non-carbon elements include an element selected from oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, or boron. These graphene sheets may be further chemically functionalized.
  • the polymer component may contain a plastic, a rubber, a thermoplastic elastomer, a polymer matrix composite, a rubber matrix composite, or a combination thereof.
  • the polymer component contains a thermoplastic, a thermoset resin, an
  • interpenetrating network a rubber, a thermoplastic elastomer, a natural polymer, or a
  • the polymer component contains a plastic selected from acrylonitrile-butadiene- styrene copolymer (ABS), styrene-acrylonitrile copolymer (SAN), polycarbonate, polyamide or nylon, polystyrene, high-impact polystyrene (HIPS), polyacrylate, polyethylene, polypropylene, polyacetal, polyester, polyether, polyether sulfone, poly ether ether ketone, poly sulfone, polyphenylene oxide (PPO), polyvinyl chloride (PVC), polyimide, polyamide imide, polyurethane, polyurea, or a combination thereof.
  • ABS acrylonitrile-butadiene- styrene copolymer
  • SAN styrene-acrylonitrile copolymer
  • HIPS high-impact polystyrene
  • PPO polyphenylene oxide
  • PVC polyvinyl chloride
  • polyimide polyamide imide
  • the plated metal is preferably selected from copper, nickel, aluminum, chromium, tin, zinc, titanium, silver, gold, an alloy thereof, or a combination thereof. There is no limitation on the type of metals that can be plated.
  • the graphene sheets may be further decorated with nanoscaled particles or coating (having a diameter or thickness from 0.5 nm to 100 nm) of a catalytic metal selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof, and wherein the catalytic metal is different in chemical composition than the plated metal.
  • a catalytic metal selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof, and wherein the catalytic metal is different in chemical composition than the plated metal.
  • the polymer component surface prior to being deposited with the first layer of graphene sheets and a conductive filler, contains only small openings or pores having a diameter or a depth ⁇ 0.1 pm.
  • the multiple graphene sheets and the conductive filler are bonded to the polymer component surface with an adhesive resin having an adhesive-to- graphene weight ratio from 1/5000 to 1/10, preferably from 1/1000 to 1/100.
  • the disclosure also provides a method of producing a surface-metalized polymer article, the method comprising: (a) providing a graphene/conductive filler mixture dispersion comprising multiple graphene sheets and a conductive filler dispersed in a liquid medium, bringing the polymer component surface into contact with the dispersion and facilitating deposition of the graphene sheets and the conductive filler onto a surface of the surface-treated polymer component wherein the graphene sheets and the conductive filler are bonded to the surface to form a layer of bonded graphene sheets and conductive filler covering the polymer component surface (i.e. to form a graphene/conductive filler-covered polymer component surface); and (b) chemically, physically, electrochemically or electrolytically depositing a layer of a metal onto the covered polymer component surface to form the surface-metalized polymer article.
  • the method further comprises, prior to step (a), a step of subjecting the polymer component surface to a grinding treatment, an etching treatment, or a combination thereof.
  • step (a) includes a step of subjecting the polymer component surface to an etching treatment using an etchant selected from an acid, an oxidizer, a metal salt, or a combination thereof.
  • the method further comprises, prior to step (a), a step of subjecting the polymer component surface to an etching treatment without using chromic acid or
  • the method further comprises, prior to step (a), a step of subjecting the polymer component surface to an etching treatment using an etchant selected from an acid, an oxidizer, a metal salt, or a combination thereof under a mild etching condition wherein etching is conducted at a sufficiently low temperature for a sufficiently short period of time so as not to create microcavems having an average size greater than 0.1 mhi
  • the graphene sheets may be further decorated with nanoscaled particles or coating of a catalytic metal, having a diameter or thickness from 0.5 nm to 100 nm, selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof.
  • a catalytic metal having a diameter or thickness from 0.5 nm to 100 nm, selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof.
  • step (a) includes immersing or dipping the polymer component in the dispersion and then removing the polymer component from the dispersion to effect deposition of graphene sheets and the conductive filler onto a surface of the surface-treated polymer component wherein the graphene sheets and the conductive filler are bonded to the surface to form a layer of bonded graphene sheets and conductive filler.
  • step (b) may contain immersing the polymer component in a metallizing bath.
  • step (b) includes a step of dipping the polymer component containing the layer of bonded graphene sheets/conductive filler into and then retreating from a chemical plating bath containing a metal salt dissolved in a liquid medium to effect metallization of the polymer component surface.
  • the graphene/conductive filler mixture dispersion further contains an adhesive resin having an adhesive-to-graphene weight ratio from 1/5000 to 1/10.
  • the graphene sheets may be further decorated with nanoscaled particles or coating of a catalytic metal, having a diameter or thickness from 0.5 nm to 100 nm, selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof.
  • the liquid medium may contain permanganic acid, phosphoric acid, nitric acid, or a combination thereof that is dissolved in said liquid medium.
  • the liquid medium contains an acid, an oxidizer, a metal salt, or a combination thereof dissolved therein.
  • Step (b) may contain immersing the polymer component in a metallizing bath to accomplish chemical plating or electroless plating.
  • the high electrical conductivity of deposited graphene sheets and conductive filler enables plating of metal layer(s) on graphene/conductive filler-coated polymer component surfaces.
  • the disclosure also provides a graphene/conductive filler mixture dispersion comprising multiple graphene sheets and a conductive filler dispersed in a liquid medium wherein the multiple graphene sheets contain single-layer or few-layer graphene sheets selected from a pristine graphene material having essentially zero % of non-carbon elements, or a non-pristine graphene material having 0.001% to 25% by weight of non-carbon elements wherein said non- pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, doped graphene, chemically functionalized graphene, or a combination thereof, and wherein the dispersion further contains one or multiple species selected from (i) an adhesive resin dissolved or dispersed in the liquid medium, wherein an adhesive-to-graphene weight ratio is from 1/5000 to 1/10; (ii) an etchant selected from an
  • the conductive filler may be selected from metal nanowires, carbon fibers, carbon nanofibers, carbon-coated fibers, conductive polymer fibers, nanofibers or nanowires of Sn0 2 , Zn0 2 , ln 2 0 3 , or indium-tin oxide (GGO), a conductive polymer not in a fiber form, or a combination thereof.
  • the metal nanowires may be selected from nanowires of silver (Ag), gold (Au), copper (Cu), platinum (Pt), zinc (Zn), cadmium (Cd), cobalt (Co), molybdenum (Mo), aluminum (Al), or a combination thereof.
  • the conductive polymer is preferably selected from the group consisting of polydiacetylene, polyacetylene (PAc), polypyrrole (PPy), polyaniline (PAni), polythiophene (PTh), polyisothionaphthene (PITN), polyheteroarylenvinylene (PArV), in which the heteroarylene group can be the thiophene, furan or pyrrole, poly-p-phenylene (PpP), polyphthalocyanine (PPhc) and the like, and their derivatives, and combinations thereof.
  • the nanoscaled particles or coating of a catalytic metal may be deposited or decorated on surfaces of said multiple graphene sheets.
  • the acid may be selected from permanganic acid, phosphoric acid, nitric acid, chromic acid, chromosulfuric acid, carboxylic acid, acetic acid, and ascorbic acid, or a combination thereof.
  • FIG. 1 A flow chart showing the most commonly used process for producing oxidized graphene sheets that entails chemical oxidation/intercalation, rinsing, and high-temperature exfoliation procedures.
  • FIG. 2 Schematic of a graphene-mediated metallized polymer component.
  • FIG. 3 Schematic of a system for graphene-mediated metallization of polymer articles.
  • graphene sheets means a material comprising one or more planar sheets of bonded carbon atoms that are densely packed in a hexagonal crystal lattice in which carbon atoms are bonded together through strong in-plane covalent bonds, and further containing an intact ring structure throughout a majority of the interior. Preferably at least 80% of the interior aromatic bonds are intact. In the c-axis (thickness) direction, these graphene planes may be weakly bonded together through van der Waals forces. Graphene sheets may contain non-carbon atoms at their edges or surface, for example OH and COOH functionalities.
  • graphene sheets includes pristine graphene, graphene oxide, reduced graphene oxide, halogenated graphene including graphene fluoride and graphene chloride, nitrogenated graphene, hydrogenated graphene, doped graphene, functionalized graphene, and combinations thereof.
  • non-carbon elements comprise 0 to 25 weight % of graphene sheets.
  • Graphene oxide may comprise up to 53% oxygen by weight.
  • doped graphene encompasses graphene having less than 10% of a non-carbon element. This non-carbon element can include hydrogen, oxygen, nitrogen, magnesium, iron, sulfur, fluorine, bromine, iodine, boron, phosphorus, sodium, and combinations thereof.
  • Graphene sheets may comprise single-layer graphene or few-layer graphene, wherein the few-layer graphene is defined as a graphene platelet formed of less than 10 graphene planes. Graphene sheets may also comprise graphene nanoribbons.“Pristine graphene” encompasses graphene sheets having essentially zero % of non-carbon elements. “Nanographene platelet” (NGP) refers to a graphene sheet having a thickness from less than 0.34 nm (single layer) to 100 nm (multi-layer).
  • substantially and its variations are defined as being largely but not necessarily wholly what is specified as understood by one of ordinary skill in the art, and in one non-limiting embodiment substantially refers to ranges within 10%, within 5%, within 1%, or within 0.5% of a referenced range.
  • the present disclosure provides a surface-metalized polymer article comprising a polymer component having a surface, a first layer composed of multiple graphene sheets and a conductive filler coated on the polymer component surface, and a second layer of a plated metal deposited on this first layer, wherein the multiple graphene sheets contain single-layer or few- layer graphene sheets selected from a pristine graphene material having essentially zero % of non-carbon elements, or a non-pristine graphene material having 0.001% to 25% by weight of non-carbon elements wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, doped graphene, chemically
  • the first layer has a thickness typically from 0.34 nm to 30 pm (preferably from 1 nm to 1 pm and further preferably from 1 nm to 100 nm).
  • the second layer (covering metal layer) preferably has a thickness from 0.5 nm to 1.0 mm, more preferably from 1 nm to 10 pm, and most preferably from 10 nm to 1 pm.
  • This metal-plated polymer article can be easily and readily produced using surprisingly simple and effective methods also herein described.
  • Functionalized graphene sheets are surprisingly capable of bonding to many types of polymer component surfaces without using an adhesive resin.
  • the apparatus may comprise: (a) a graphene deposition chamber (e.g. a graphene dispersion bath 12) that accommodates a graphene dispersion 14 comprising multiple graphene sheets and an optional conductive filler dispersed in a first liquid medium and an optional adhesive resin dissolved in the first liquid medium, wherein the graphene deposition chamber is operated to deposit the graphene sheets and optional conductive filler to a surface of at least a polymer component for forming at least a graphene-coated polymer component (e.g. a faucet assembly 10); and (b) a metallization chamber (e.g. a metal plating bath 22), in a working relationship with the graphene deposition chamber (e.g. disposed nearby the graphene dispersion bath 12), which
  • the graphene deposition chamber 12 has an inlet 16 through which fresh graphene dispersion may be pumped into the graphene deposition chamber and an outlet 18 through which spent graphene dispersion may be pumped out, respectively.
  • the metallization chamber 22 has an inlet 26 through which fresh plating solution may be pumped into the metallization chamber and an outlet 28 through which spent graphene dispersion may be pumped out, respectively.
  • the apparatus may further comprise a movable carrier for carrying the at least a polymer component and bringing the at least a polymer component in contact with the graphene dispersion (e.g. for dipping the at least a polymer component into the graphene dispersion bath and then retreating the at least one polymer component from this bath) for producing the at least a graphene-coated polymer component and/or bringing the at least a graphene-coated polymer component in contact with the plating solution (e.g.
  • the apparatus may further comprise a drying, heating, or curing provision 32 in a working relation with the graphene deposition chamber (e.g. above and between the graphene dispersion bath and the metallization chamber) for partially or completely removing the first liquid medium from the at least a graphene-coated polymer component and/or for polymerizing or curing the optional adhesive resin for producing the at least a graphene-coated polymer component containing multiple graphene sheets that are bonded to the surface of the at least a polymer component.
  • a faucet assembly 10 is shown to have been retreated from the graphene deposition bath 12 and is being heated, dried, or cured. Upon completion of this drying/heating/curing procedure, this faucet will be dipped into the metallization bath 22.
  • the plating solution 24 may contain a chemical plating solution, an electrochemical plating solution, or an electrolytical solution.
  • the plating solution contains a chemical plating solution comprising a metal salt dissolved in water or an organic solvent (e.g. CuS0 4 or N1NO 3 dissolved in water for Cu plating or Ni plating).
  • a metal salt dissolved in water or an organic solvent (e.g. CuS0 4 or N1NO 3 dissolved in water for Cu plating or Ni plating).
  • the various graphene sheets bonded on a polymer component surface are surprisingly capable of attracting metal ions to the graphene-covered or graphene-coated polymer component surface.
  • the adhesion of metal on this surface is surprisingly strong, scratch-resistant, and hard.
  • the deposited metal layer provides the desired glossiness and metal appearance on the polymer component surface.
  • the operation of the aforementioned procedures may be conducted in a continuous or intermittent manner and can be fully automated.
  • the conductive filler is selected from metal nanowires, carbon fibers, carbon nanofibers, carbon-coated fibers, conductive polymer fibers, nanofibers or nanowires of Sn0 2 , Zn0 2 , ln 2 0 3 , or indium-tin oxide (ITO), a conductive polymer not in a fiber form, or a combination thereof.
  • the metal nanowires are preferably selected from nanowires of silver (Ag), gold (Au), copper (Cu), platinum (Pt), zinc (Zn), cadmium (Cd), cobalt (Co), molybdenum (Mo), aluminum (Al), or a combination thereof.
  • the conductive polymer is preferably selected from the group consisting of polydiacetylene, polyacetylene (PAc), polypyrrole (PPy), polyaniline (PAni), polythiophene (PTh), polyisothionaphthene (PITN), polyheteroarylenvinylene (PArV), in which the heteroarylene group can be the thiophene, furan or pyrrole, poly-p-phenylene (PpP), polyphthalocyanine (PPhc) and the like, and their derivatives, and combinations thereof.
  • the chemically functionalized graphene sheets contain a chemical functional group selected from alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, amine group, sulfonate group (— S0 3 H), aldehydic group, quinoidal, fluorocarbon, or a combination thereof.
  • the functional group is selected from the group consisting of hydroxyl, peroxide, ether, keto, and aldehyde.
  • the functionalizing agent contains a 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(-0- 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(alkylether), R" is fluoroalkyl, fluoroaryl, fluorocycloalkyl, fluoroaralkyl or
  • the functional group may be 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, and combinations thereof.
  • the present disclosure also provides a method of metallizing a polymer surface (e.g. surface of an electronically non-eonduetive plastic).
  • a polymer surface e.g. surface of an electronically non-eonduetive plastic.
  • the plastic surface of a plastic article or the plastic surfaces of several plastic articles are metallized.
  • polymer galvanizing also called polymer galvanizing or polymer metallization
  • metals also called polymer galvanizing or polymer metallization
  • polymer galvanizing methods laminates which combine advantages of polymers and metals are produced.
  • the use of polymer components can achieve a distinct reduction in weight in comparison to metal parts.
  • Galvanization of polymer moldings is often conducted for decorative purposes, for EMI shielding, or for surface property modifications.
  • the parts are usually secured in frames and contacted with a plurality of different treatment fluids in a particular process sequence.
  • the plastics are typically pretreated to remove impurities, such as greases, from the surface.
  • etching treatments are used to roughen the surface to ensure adequate adhesion of the subsequent metal layers to the polymer surface.
  • the formation of a homogeneous structure in the form of recesses (e.g. surface openings or microcavems) on the plastic surface is particularly crucial.
  • the roughened surface is treated with activators to form a catalytic surface for a subsequent chemical metallization or electroless plating.
  • either the ionogenic activators or colloidal systems are used.
  • plastic surfaces for activation with ionogenic systems are first treated with tin(II) ions, giving rise to firmly adhering gels of tin oxide hydrate after the treatment and rinsing with water.
  • palladium salt solution palladium nuclei are formed on the surface through redox reaction with the tin(II) species. These palladium nuclei are catalytic for the chemical metallization.
  • colloidal palladium solutions are used, formed by reaction of palladium chloride with tin(II) chloride in the presence of excess hydrochloric acid.
  • the plastic parts are typically first chemically metallized using a metastable solution of a metallization bath.
  • a metallization bath generally comprise the metal to be deposited in the form of salts in an aqueous solution and a reducing agent for the metal salt.
  • the chemical metallization baths come into contact with the metal nuclei on the plastic surface (e.g. the palladium seeds), metal is formed by reduction, which is deposited on the surface as a firmly adhering layer.
  • the chemical metallization step is commonly used to deposit copper, nickel or a nickel alloy with phosphorus and/or boron.
  • the chemically metallized polymer surface may then be electrolytically deposited further with metal layers.
  • an electrolytic deposition of copper layers or further nickel layers is conducted before the desired decorative chromium layer is applied electrochemically.
  • the most commonly used etchant is the chromium- sulfuric acid or chromo sulfuric acid (chromium trioxide in sulfuric acid), especially for ABS (acrylonitrile-butadiene-styrene copolymer) or polycarbonate.
  • Chromium-sulfuric acid is very toxic and requires special precautions in the etching procedure, after treatment, and disposal. Because of chemical processes in the etching treatment (e.g. the reduction of the chromium compound used), the chromium-sulfuric acid etchant is used up and is generally not reusable.
  • a critical process step in plastic galvanizing is the creation of microcaverns to enable the adhesion of the metal on the plastic surface.
  • microcavems serve, in the later metallization steps, as the starting point for the growth of the metal nuclei.
  • These microcaverns in general, have a size on the order of 0.1 to 10 pm. Especially, these microcaverns show a depth (i.e. an extent from the plastic surface toward the interior) in the range from 0.1 to 10 pm.
  • surface microcavems can be stress concentration sites that weaken the strength of the plastic component.
  • the surface first is activated with colloidal palladium or ionogene palladium. This activation, in the case of the colloidal process, is followed by a removal of a protective tin colloid or, in the case of the ionogene process, a reduction to the elemental palladium. Subsequently, copper or nickel is chemically deposited on the plastic surface as a conducting layer. Following this, galvanizing or metallizing takes place. In practice, this direct metallizing of the plastic surface works only for certain plastics.
  • the present disclosure provides a graphene-mediated method of producing metallized polymer articles.
  • the disclosed method overcomes all of these problems.
  • the method comprises: (a) optionally treating a surface of a polymer component to prepare a surface-treated polymer component (this procedure being optional since the graphene dispersion per se is capable of pre-treating the polymer surface); (b) providing a graphene dispersion (also herein referred to as graphene/conductive filler mixture dispersion) comprising multiple graphene sheets (functionalized or un-functionalized) and a conductive filler (in the form of nanofibers, nanoparticles, nanowires, etc.) dispersed in a liquid medium, bringing the surface-treated or un-treated polymer component into contact with the graphene dispersion, and enabling deposition of the graphene sheets and the conductive filler onto a surface of the surface-treated polymer component wherein the graphene sheets and the conductive filler are bonded to the surface to form a layer of bonded graphene sheets/conductive filler that covers (partially or fully) a polymer component surface; and (c) chemical
  • the polymer component may be selected from polyethylene, polypropylene, polybutylene, polyvinyl chloride, polycarbonate, acrylonitrile-butadiene- styrene (ABS), polyester, polyvinyl alcohol, poly vinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene oxide (PPO), poly methyl methacrylate (PMMA), a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • ABS acrylonitrile-butadiene- styrene
  • polyester polyvinyl alcohol, poly vinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene oxide (PPO), poly methyl methacrylate (PMMA), a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • PVDF poly vinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PPO polypheny
  • the polymer may also be selected from phenolic resin, poly furfuryl alcohol, polyacrylonitrile, polyimide, polyamide, polyoxadiazole, polybenzoxazole, polybenzobisoxazole, polythiazole, polybenzothiazole, polybenzobisthiazole, poly(p-phenylene vinylene), polybenzimidazole, polybenzobisimidazole, a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • step (a) is omitted from the process since the liquid medium in the graphene dispersion is generally capable of removing grease and other undesirable species from polymer component surfaces.
  • Some liquid mediums in graphene dispersions can further provide etching effects to create small surface recesses having a depth ⁇ 0.1 pm (a mild etching condition). In these situations, the entire process requires only three simple steps.
  • step (a) can include a step of subjecting the polymer component surface to a grinding treatment, an etching treatment, or a combination thereof.
  • step (a) includes a step of subjecting the polymer component surface to an etching treatment using an etchant selected from an acid, an oxidizer, a metal salt, or a combination thereof.
  • step (a) includes a step of subjecting the polymer component surface to an etching treatment without using chromic acid or chromosulfuric acid.
  • step (a) includes a step of subjecting the polymer component surface to an etching treatment using an etchant selected from an acid, an oxidizer, a metal salt, or a combination thereof under a mild etching condition wherein etching is conducted at a sufficiently low temperature for a sufficiently short period of time so as not to create microeaveras having an average size greater than 0 1 pm.
  • an etchant selected from an acid, an oxidizer, a metal salt, or a combination thereof under a mild etching condition wherein etching is conducted at a sufficiently low temperature for a sufficiently short period of time so as not to create microeaveras having an average size greater than 0 1 pm.
  • the mild etching referred to in the invention means that the“etching”, or the treatment of the plastic surface with a etching solution occurs at low temperatures and/or within a shorter time period at a low concentration of the etching solution. Mild etching conditions can be realized when one of the preceding three conditions is met.
  • the low temperature referred to in the disclosure means a maximum temperature of 40°C, preferably ⁇ 30°C, and most preferably from l5°C to 25°C. With the low temperatures mentioned above, the pre-treatment with the etching solution takes place over a time period of 3 to 15 minutes, preferably 5 to 15 minutes and even more preferably 5 to 10 minutes. The treatment period is the shorter the higher the temperature.
  • the etching treatment takes place at temperatures of 40°C to 95°C, preferably 50°C to 70°C, for a treatment period of 15 seconds to 5 minutes, preferably 0.5 to 3 minutes.
  • the process temperature and/or process time is selected in accordance with the type of the etching solution employed.
  • Mild etching also means that, contrary to the prior art processes referred to above, roughening of the polymer surface, or the creation of microeaverns in the polymer surface does not occur.
  • the microeaverns created with etching according to the prior art process normally have a diameter or depth in the size range of 0.1 to 10 pm.
  • the etching conditions are adjusted so that only small openings or pores are created in the polymer surface which have a diameter and especially a depth of ⁇ 0.1 pm, with ⁇ 0.05 pm preferred.
  • depth means the extent of the openings/gateways from the polymer surface into the polymer interior.
  • the liquid medium in the graphene dispersion normally can create openings or pores having a size ⁇ 0.1 pm. Contrary to what the prior art teachings suggest, we have surprisingly observed that the presently disclosed graphene-mediated metallization approach does not require the creation of microcavems greater than 0.1 pm in size. The approach works even on highly smooth surface.
  • the etching treatment can be realized with a etching solution and/or by a plasma treatment or by plasma etching, ion bombardment, etc.
  • an etching solution used for etching contains at least one oxidizer.
  • Mild etching within the scope of the disclosure also means that an oxidizer is used in a low
  • etching is by an acid etching solution which contains at least one oxidizer.
  • the oxidizer and/or the acid or basic solution may be added into the graphene dispersion and, as such, step (a) and step (b) are essentially combined into one single step.
  • an aqueous etching solution which contains permanganate and phosphoric acid (H3PO4) and/or sulfuric acid.
  • Potassium permanganate may be used as the permanganate.
  • an acid etching solution which only contains phosphoric acid or principally phosphoric acid and only a small amount of sulfuric acid.
  • etching treatment is by a basic aqueous solution, containing permanganate.
  • potassium permanganate is preferably used.
  • the basic aqueous solution may contain lye.
  • the type of etching solution used depends on the type of polymer to be treated.
  • the preferred concentration of the oxidizer in the etching solution is 0.05 to 0.6 mol/l.
  • the etching solution contains 0.05 to 0.6 mol/l permanganate or persulfate.
  • the etching solution may contain 0.1 to 0.5 mol/l periodate or hydrogen peroxide.
  • the preferred permanganate proportion is 1 g/l up to the solubility limit of the permanganate, preferably potassium permanganate.
  • the permanganate solution preferably contains 2 to 15 g/l permanganate, more preferably 2 to 15 g/l potassium permanganate.
  • the permanganate solution may contain a wetting agent.
  • Mild etching can also be achieved by the use of a dilute aqueous persulfate solution or periodite solution or a dilute aqueous peroxide solution (used as a separate etching solution or as part of the graphene dispersion).
  • the mild etching treatment with an etching solution is carried out while agitating the solution.
  • the plastic surface is rinsed, for example, for 1 to 3 minutes in water.
  • the treatment with the metal salt solution is conducted at a temperature ⁇ 30°C, preferably between l5°C and 25 °C (including room temperature). In practice, the treatment with the metal salt solution is performed without agitation.
  • the preferred treatment time is 30 seconds to 15 minutes, preferably 3 to 12 minutes.
  • a metal salt solution is used which has a pH value of between 7.5 and 12.5, preferably adjusted to between 8 and 12.
  • a metal salt solution is used which contains ammonia and/or at least one amine.
  • the above-mentioned pH value adjustment can be effected with the help of ammonia, and an alkaline metal salt solution is preferably used.
  • a metal salt solution which contains one or more amines.
  • the metal salt solution may contain monoethanolamine and/or
  • Treatment with the metal salt solution means preferably the immersion of the polymer component surface into the metal salt solution.
  • step (b) includes immersing or dipping the surface-treated or un treated polymer component in the graphene dispersion and then removing the polymer component from the graphene dispersion to effect deposition of graphene sheets and the conductive filler onto a surface of the surface-treated polymer component wherein the graphene sheets and the conductive fillers are bonded to the surface to form a layer of bonded graphene sheets/conductive filler.
  • step (b) includes immersing or dipping the surface-treated or un treated polymer component in the graphene dispersion and then removing the polymer component from the graphene dispersion to effect deposition of graphene sheets and the conductive filler onto a surface of the surface-treated polymer component wherein the graphene sheets and the conductive fillers are bonded to the surface to form a layer of bonded graphene sheets/conductive filler.
  • the adhesive resin layer may be formed of an adhesive resin composition including an adhesive resin as a main ingredient.
  • the adhesive resin composition may include a curing agent and a coupling agent along with the adhesive resin. Examples of the
  • adhesive resin may include an ester resin, a urethane resin, a urethane ester resin, an
  • the curing agent may be present in an amount of 1 to 30 parts by weight based on 100 parts by weight of the adhesive resin.
  • the coupling agent may include epoxy silane compounds. Curing of this adhesive layer may be conducted via heat, UV, or ionizing radiation. This can involve heating the layers coated with the heat-curable composition to a temperature of at least 70°C, preferably of 90°C to l50°C, for at least 1 minute (typically up to 2 hours and more typically from 2 minutes to 30 minutes), so as to form a hard coating layer.
  • the polymer component surfaces may be brought to be in contact with the graphene or CNT dispersion using dipping, coating (e.g. doctor-blade coating, bar coating, slot-die coating, comma coating, reversed-roll coating, etc.), roll-to-roll process, inkjet printing, screen printing, micro-contact, gravure coating, spray coating, ultrasonic spray coating, electrostatic
  • the thickness of the hard coat or adhesive layer is generally about 1 nm to 10 pm, preferably 10 nm to 2 pm.
  • the polyfunctional epoxy monomer may be selected preferably from diglycerol tetraglycidyl ether, dipentaerythritol tetraglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether (e.g. pentaerythritol tetraglycidyl ether), or a combination thereof.
  • functional epoxy monomer can be selected from the group consisting of trimethylolethane triglycidyl ether, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, triphenylolmethane triglycidyl ether, trisphenol triglycidyl ether, tetraphenylol ethane triglycidyl ether, tetraglycidyl ether of tetraphenylol ethane, p-aminophenol triglycidyl ether, 1,2,6- hexanetriol triglycidyl ether, glycerol triglycidyl ether, diglycerol triglycidyl ether, glycerol ethoxylate triglycidyl ether, castor oil triglycidyl ether, propoxylated glycerine trig
  • polypropylene glycol diglycidyl ether dibromoneopentyl glycol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, (3,4-epoxycyclohexane) methyl 3,4-epoxycylohexylcarboxylate and mixtures.
  • the heat-curable compositions of the present disclosure advantageously further contain small amounts, preferably from 0.05 to 0.20 % by weight, of at least one surface active compound.
  • the surface active agent is important for good wetting of the substrate resulting in satisfactory final hard-coating.
  • the UV radiation curable resins and lacquers usable for the adhesive layer useful in this disclosure are those derived from photo polymerizable monomers and oligomers, such as acrylate and methacrylate oligomers (the term“(meth)acrylate” used herein refers to acrylate and methacrylate), of polyfunctional compounds, such as polyhydric alcohols and their derivatives having (meth)acrylate functional groups such as ethoxylated trimethylolpropane
  • tri(meth)acrylate tripropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, l,6-hexanediol di(meth)acrylate, or neopentyl glycol di(meth)acrylate and mixtures thereof, and acrylate and methacrylate oligomers derived from low-molecular weight polyester resin, polyether resin, epoxy resin, polyurethane resin, alkyd resin, spiroacetal resin, epoxy acrylates, polybutadiene resin, and polythiol-polyene resin.
  • the UV polymerizable monomers and oligomers are coated (e.g. after retreating from dipping) and dried, and subsequently exposed to UV radiation to form an optically clear cross- linked abrasion resistant layer.
  • the preferred UV cure dosage is between 50 and 1000 mJ/cm .
  • UV-curable resins are typically ionizing radiation-curable as well.
  • the ionizing radiation- curable resins may contain a relatively large amount of a reactive diluent.
  • Reactive diluents usable herein include monofunctional monomers, such as ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, vinyltoluene, and N-vinylpyrrolidone, and polyfunctional monomers, for example, trimethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, l,6-hexanediol di(meth)acrylate, or neopen
  • step (c) may contain immersing the graphene-bonded polymer component in a metallizing bath.
  • the high electrical conductivity of deposited graphene sheets readily enables electro-plating of metal layer(s) on graphene/conductive filler-coated polymer component surfaces.
  • the final metallization step may be accomplished by using a chemical plating method without using an expensive noble metal solution.
  • This step can include dipping (immersing) a graphene/conductive filler-coated polymer component in a chemical plating bath which contains a metal salt (salt of an intended metal, such as Cu, Ni, or Co) dissolved in a liquid medium (e.g. CuS0 4 in water or N1NO 3 in water).
  • a metal salt salt of an intended metal, such as Cu, Ni, or Co
  • a copper metal plating bath may comprise a copper salt (or Ni salt) and an additive consumption-inhibiting compound.
  • the additive consumption-inhibiting compound may comprise methyl sulfoxide, methyl sulfone, tetramethylene sulfoxide, thioglycolic acid, 2 (5H) thiophenone, l,4-dithiane, trans-l,2-dithiane, tetrahydrothiophene-3- one, 3-thiophenemethanol, l,3,5-trithiane, 3-thiopheneacetic acid, thiotetronic acid, crown thioethers, tetrapyrids, dipropyltrisulfide, bis(3 -triethoxy silyl propyltetrasulfide, dimethyl tetrasulfide, methyl methanethiosulfate, (2-sulfonatoethyl) methane, p-tolyld
  • 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).
  • the carbon nanotube (CNT) refers to a tubular structure grown with a single wall or multi-wall.
  • Carbon nanotubes (CNTs) and carbon nanofibers (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.
  • Our research group pioneered the development of graphene materials and related production processes as early as 2002: (1) B. Z. Jang and W. C. Huang,“Nano-scaled Graphene Plates,” U.S. Pat. No. 7,071,258 (07/04/2006), application submitted on October 21, 2002; (2) B. Z. Jang, et al.“Process for Producing Nano-scaled Graphene Plates,” U.S. Patent Application No. 10/858,814 (06/03/2004) (U.S. Patent Pub. No. 2005/0271574); and (3) B. Z. Jang, A.
  • a single-layer graphene sheet is composed of carbon atoms occupying a two-dimensional hexagonal lattice.
  • Multi-layer graphene is a platelet composed of more than one graphene plane.
  • Individual single-layer graphene sheets and multi-layer graphene platelets are herein collectively called nanographene platelets (NGPs) or graphene materials.
  • NGPs include pristine graphene (essentially 99% of carbon atoms), slightly oxidized graphene ( ⁇ 5% by weight of oxygen), graphene oxide (> 5% by weight of oxygen), slightly fluorinated graphene ( ⁇ 5% by weight of fluorine), graphene fluoride ((> 5% by weight of fluorine), other halogenated graphene, and chemically functionalized graphene.
  • NGPs have been found to have a range of unusual physical, chemical, and mechanical properties. For instance, graphene was found to exhibit the highest intrinsic strength and highest thermal conductivity of all existing materials. Although practical electronic device applications for graphene (e.g., replacing Si as a backbone in a transistor) are not envisioned to occur within the next 5-10 years, its application as a nanofiller in a composite material and an electrode material in energy storage devices is imminent. The availability of processable graphene sheets in large quantities is essential to the success in exploiting composite, energy, and other applications for graphene.
  • NGPs and NGP nanocomposites were recently reviewed by us [Bor Z. Jang and A Zhamu,“Processing of Nano Graphene Platelets (NGPs) and NGP Nanocomposites: A Review,” J. Materials Sci. 43 (2008) 5092-5101].
  • FIG. 1 A highly useful approach (FIG. 1) entails treating natural graphite powder with an intercalant and an oxidant (e.g., concentrated sulfuric acid and nitric acid, respectively) to obtain a graphite intercalation compound (GIC) or, actually, graphite oxide (GO).
  • an intercalant e.g., concentrated sulfuric acid and nitric acid, respectively
  • GAC graphite intercalation compound
  • GO graphite oxide
  • the GIC or GO is exposed to a high temperature (typically 800-l,050°C) for a short period of time (typically 15 to 60 seconds) to exfoliate or expand the GIC or GO for the formation of exfoliated or further expanded graphite, which is typically in the form of a“graphite worm” composed of graphite flakes that are still
  • approach 1 basically entails three distinct procedures: first expansion (oxidation or intercalation), further expansion (or“exfoliation”), and separation.
  • the expanded or exfoliated GO powder is dispersed in water or aqueous alcohol solution, which is subjected to ultrasonication. It is important to note that in these processes, ultrasonification is used after intercalation and oxidation of graphite (i.e., after first expansion) and typically after thermal shock exposure of the resulting GIC or GO (after second expansion).
  • the GO powder dispersed in water is subjected to an ion exchange or lengthy purification procedure in such a manner that the repulsive forces between ions residing in the inter-planar spaces overcome the inter-graphene van der Waals forces, resulting in graphene layer separations.
  • the starting material for the preparation of graphene sheets or NGPs is a graphitic material that may be selected from the group consisting of natural graphite, artificial graphite, graphite oxide, graphite fluoride, graphite fiber, carbon fiber, carbon nanofiber, carbon nanotube, mesophase carbon micro-bead (MCMB) or carbonaceous micro sphere (CMS), soft carbon, hard carbon, and combinations thereof.
  • MCMB mesophase carbon micro-bead
  • CMS carbonaceous micro sphere
  • Graphite oxide may be prepared by dispersing or immersing a laminar graphite material (e.g., powder of natural flake graphite or synthetic graphite) in an oxidizing agent, typically a mixture of an intercalant (e.g., concentrated sulfuric acid) and an oxidant (e.g., nitric acid, hydrogen peroxide, sodium perchlorate, potassium permanganate) at a desired temperature (typically 0-70°C) for a sufficient length of time (typically 4 hours to 5 days).
  • an intercalant e.g., concentrated sulfuric acid
  • an oxidant e.g., nitric acid, hydrogen peroxide, sodium perchlorate, potassium permanganate
  • the resulting graphite oxide particles are then rinsed with water several times to adjust the pH values to typically 2-5.
  • the resulting suspension of graphite oxide particles dispersed in water is then subjected to ultrasonication to produce a dispersion of separate graphene oxide sheets dispersed in water.
  • a small amount of reducing agent e.g. Na 4 B
  • RDO reduced graphene oxide
  • GIC graphite intercalation compound
  • the GIC particles are then exposed to a thermal shock, preferably in a temperature range of 600-1, l00°C for typically 15 to 60 seconds to obtain exfoliated graphite or graphite worms, which are optionally (but preferably) subjected to mechanical shearing (e.g. using a mechanical shearing machine or an ultrasonicator) to break up the graphite flakes that constitute a graphite worm.
  • mechanical shearing e.g. using a mechanical shearing machine or an ultrasonicator
  • the pristine graphene material is preferably produced by one of the following three processes: (A) Intercalating the graphitic material with a non-oxidizing agent, followed by a thermal or chemical exfoliation treatment in a non-oxidizing environment; (B) Subjecting the graphitic material to a supercritical fluid environment for inter-graphene layer penetration and exfoliation; or (C) Dispersing the graphitic material in a powder form to an aqueous solution containing a surfactant or dispersing agent to obtain a suspension and subjecting the suspension to direct ultrasonication to obtain a graphene dispersion.
  • a particularly preferred step comprises (i) intercalating the graphitic material with a non-oxidizing agent, selected from an alkali metal (e.g., potassium, sodium, lithium, or cesium), alkaline earth metal, or an alloy, mixture, or eutectic of an alkali or alkaline metal; and (ii) a chemical exfoliation treatment (e.g., by immersing potassium-intercalated graphite in ethanol solution).
  • a non-oxidizing agent selected from an alkali metal (e.g., potassium, sodium, lithium, or cesium), alkaline earth metal, or an alloy, mixture, or eutectic of an alkali or alkaline metal
  • a chemical exfoliation treatment e.g., by immersing potassium-intercalated graphite in ethanol solution.
  • a preferred step comprises immersing the graphitic material to a supercritical fluid, such as carbon dioxide (e.g., at temperature T > 3l°C and pressure P > 7.4 MPa) and water (e.g., at T > 374°C and P > 22.1 MPa), for a period of time sufficient for inter graphene layer penetration (tentative intercalation).
  • a supercritical fluid such as carbon dioxide (e.g., at temperature T > 3l°C and pressure P > 7.4 MPa) and water (e.g., at T > 374°C and P > 22.1 MPa)
  • a sudden de pressurization to exfoliate individual graphene layers.
  • suitable supercritical fluids include methane, ethane, ethylene, hydrogen peroxide, ozone, water oxidation (water containing a high concentration of dissolved oxygen), or a mixture thereof.
  • a preferred step comprises (a) dispersing particles of a graphitic material in a liquid medium containing therein a surfactant or dispersing agent to obtain a suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves (a process commonly referred to as ultrasonication) at an energy level for a sufficient length of time to produce a graphene dispersion of separated graphene sheets (non-oxidized NGPs) dispersed in a liquid medium (e.g. water, alcohol, or organic solvent).
  • a liquid medium e.g. water, alcohol, or organic solvent
  • NGPs can be produced with an oxygen content no greater than 25% by weight, preferably below 20% by weight, further preferably below 5%. Typically, the oxygen content is between 5% and 20% by weight.
  • the oxygen content can be determined using chemical elemental analysis and/or X-ray photoelectron spectroscopy (XPS).
  • the laminar graphite materials used in the prior art processes for the production of the GIC, graphite oxide, and subsequently made exfoliated graphite, flexible graphite sheets, and graphene platelets were, in most cases, natural graphite.
  • the starting material may be selected from the group consisting of natural graphite, artificial graphite (e.g., highly oriented pyrolytic graphite, HOPG), graphite oxide, graphite fluoride, graphite fiber, carbon fiber, carbon nanofiber, carbon nanotube, mesophase carbon microbead (MCMB) or carbonaceous microsphere (CMS), soft carbon, hard carbon, and combinations thereof.
  • All of these materials contain graphite crystallites that are composed of layers of graphene planes stacked or bonded together via van der Waals forces.
  • graphite multiple stacks of graphene planes, with the graphene plane orientation varying from stack to stack, are clustered together.
  • carbon fibers the graphene planes are usually oriented along a preferred direction.
  • soft carbons are carbonaceous materials obtained from carbonization of liquid-state, aromatic molecules. Their aromatic ring or graphene structures are more or less parallel to one another, enabling further graphitization.
  • Hard carbons are carbonaceous materials obtained from aromatic solid materials (e.g., polymers, such as phenolic resin and polyfurfuryl alcohol). Their graphene structures are relatively randomly oriented and, hence, further graphitization is difficult to achieve even at a temperature higher than 2,500°C. But, graphene sheets do exist in these carbons.
  • 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 used in the graphene deposition of polymer component surfaces.
  • the nitrogenation of graphene can be conducted by exposing a graphene material, such as graphene oxide, to ammonia at high temperatures (200°C -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°C -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°C -250°C.
  • 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 disclosed graphene can contain pristine or non-pristine graphene and the disclosed method allows for this flexibility. These graphene sheets all can be chemically functionalized.
  • Graphene sheets have a significant proportion of edges that correspond to the edge planes of graphite crystals.
  • the carbon atoms at the edge planes are reactive and must contain some heteroatom or group to satisfy carbon valency.
  • functional groups e.g. hydroxyl and carboxylic
  • Many chemical function groups e.g. - NH 2 , etc. can be readily imparted to graphene edges and/or surfaces using methods that are well-known in the art.
  • the resulting functionalized graphene sheets may broadly have the following formula(e): [NGP]— R m , wherein m is the number of different functional group types (typically between 1 and 5), R is selected from 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(-0- 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(alkylether), R" is fluoroalkyl, fluoroaryl, fluorocycloalkyl, fluoroara
  • the function group -NH 2 is of particular interest.
  • a commonly used curing agent for epoxy resin is
  • DETA diethylenetriamine
  • one of the three -NH 2 groups may be bonded to the edge or surface of a graphene sheet and the remaining two un-reacted -NH 2 groups will be available for reacting with epoxy resin later.
  • Such an arrangement provides a good interfacial bonding between the NGP (graphene sheets) and the matrix resin of a composite material.
  • Other useful chemical functional groups or reactive molecules may be 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), hexamethylenetetramine, polyethylene polyamine, polyamine epoxy adduct, phenolic hardener, non-brominated curing agent, non-amine curatives, and combinations thereof.
  • These functional groups are multi functional, with the capability of reacting with at least two chemical species from at least two ends. Most importantly, they are capable of bonding to the edge or surface of graphene using one of their ends and, during subsequent epoxy curing stage, are able to react with epoxide or epoxy resin at one or two other ends.
  • the above-described [NGP]— R m may be further functionalized.
  • the NGPs and conductive additives may also be functionalized to produce compositions having the formula: [NGP]— [R'— A] m , where m, R' and A are as defined above.
  • the compositions of the disclosure also include NGPs upon which certain cyclic compounds are adsorbed. These include compositions of matter of the formula: [NGP]— [X— RJ m, where a is zero or a number less than 10, X is a polynuclear aromatic, polyheteronuclear aromatic or metallopolyheteronuclear aromatic moiety and R is as defined above.
  • Preferred cyclic compounds are planar.
  • More preferred cyclic compounds for adsorption are porphyrins and phthalocyanines.
  • the adsorbed cyclic compounds may be functionalized.
  • Such compositions include compounds of the formula, [NGP]— [X— A a ] m where m, a, X and A are as defined above.
  • the functionalized NGPs of the instant disclosure can be directly prepared by
  • the graphene platelets can be processed prior to being contacted with a functionalizing agent. Such processing may include dispersing the graphene platelets in a solvent. In some instances, the platelets or may then be filtered and dried prior to contact.
  • a functionalizing agent such processing may include dispersing the graphene platelets in a solvent. In some instances, the platelets or may then be filtered and dried prior to contact.
  • One particularly useful type of functional group is the carboxylic acid moieties, which naturally exist on the surfaces of NGPs if they are prepared from the acid intercalation route discussed earlier. If carboxylic acid functionalization is needed, the NGPs may be subjected to chlorate, nitric acid, or ammonium persulfate oxidation.
  • Carboxylic acid functionalized graphene sheets or platelets are particularly useful because they can serve as the starting point for preparing other types of functionalized NGPs.
  • alcohols or amides can be easily linked to the acid to give stable esters or amides. If the alcohol or amine is part of a di- or poly-functional molecule, then linkage through the O- or NH- leaves the other functionalities as pendant groups.
  • These reactions can be carried out using any of the methods developed for esterifying or aminating carboxylic acids with alcohols or amines as known in the art. Examples of these methods can be found in G. W. Anderson, et ah, J. Amer. Chem. Soc. 86, 1839 (1964), which is hereby incorporated by reference in its entirety.
  • Amino groups can be introduced directly onto graphitic platelets by treating the platelets with nitric acid and sulfuric acid to obtain nitrated platelets, then chemically reducing the nitrated form with a reducing agent, such as sodium dithionite, to obtain amino-functionalized platelets.
  • a reducing agent such as sodium dithionite
  • the graphene dispersions produced may be further added with an acid, a metal salt, an oxidizer, or a combination thereof to prepare a more reactive dispersion for use in the graphene coating of a polymer component.
  • An optional adhesive resin may also be added.
  • the surface cleaning, etching, and graphene coating can be accomplished in one step.
  • One may simply dip a polymer component into the graphene solution for several seconds to several minutes (preferably 5 seconds to 15 minutes) and then retreat the polymer component from the graphene-liquid dispersion. Upon removal of the liquid (e.g. via natural or forced vaporization), graphene sheets are naturally coated on and bonded to polymer component surfaces.
  • functionalized graphene sheets and/or conductive filler may be pre-coated or decorated with nanoscaled particles of a catalytic metal, which can catalyze the subsequent chemical metallization process.
  • This catalytic metal is preferably in the form of discrete nanoscaled particles or coating having a diameter or thickness from 0.5 nm to 100 nm and is preferably selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof.
  • the catalytic metal may alternatively be initially in a precursor form (e.g. as a metal salt) which is later converted into nanoscaled metal deposited on graphene surfaces.
  • the disclosure also provides a graphene dispersion (or graphene/conductive filler dispersion) for use in metallization of a polymer surface.
  • the graphene dispersion comprises comprising multiple graphene sheets and a conductive filler dispersed in a liquid medium wherein the multiple graphene sheets contain single-layer or few-layer graphene sheets selected from a pristine graphene material having essentially zero % of non-carbon elements, or a non- pristine graphene material having 0.001% to 25% by weight of non-carbon elements wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, doped graphene, chemically functionalized graphene, or a combination thereof, and wherein the dispersion further contains one or multiple species selected from (i) an adhesive resin dissolved or dispersed in the liquid medium, wherein
  • step (c) in the disclosed method may contain immersing the graphene/conductive filler-bonded polymer component in a metallizing bath for electroless plating of metals (chemical metallization). It is highly surprising that graphene surfaces per se (even without transition metal or noble metal) are capable of promoting conversion of some metal salts to metal deposited on graphene surfaces. This would obviate the need to use expensive noble metals (e.g. palladium or platinum) as nuclei for subsequent chemical growth of metal crystals, as required of the prior art process.
  • noble metals e.g. palladium or platinum
  • the high electrical conductivity and high specific surface areas of the deposited graphene sheets enable electro-plating of metal layer(s) on graphene-coated polymer component surfaces.
  • Graphene sheets, deposited on polymer component surfaces are also found to significantly enhance the strength, hardness, durability, and scratch resistance of the deposited metal layer.
  • the disclosed method produces a surface-metalized polymer article comprising a polymer component having a surface, a first layer of multiple graphene sheets and a conductive filler coated on the polymer component surface, and a second layer of a plated metal deposited on the first layer, wherein the multiple graphene sheets (functionalized or un-functionalized) contain single-layer graphene sheets or few-layer graphene sheets (2-10 graphene planes) wherein the multiple graphene sheets are bonded to the polymer component surface with or without an adhesive resin.
  • the first layer typically has a thickness from 0.34 nm to 30 pm (preferably from 1 nm to 1 pm and further preferably from 1 nm to 100 nm).
  • the second layer preferably has a thickness from 0.5 nm to 1.0 mm, and more preferably from 1 nm to 10 pm.
  • the doped graphene preferably contains N-doped, boron-doped, phosphorus-doped graphene, or a combination thereof.
  • the graphene sheets contain a pristine graphene and the first layer contains an adhesive resin that chemically bonds the graphene sheets to the polymer component surface.
  • the graphene sheets contain a non-pristine graphene material having a content of non-carbon elements from 0.01% to 20% by weight and the non-carbon elements include an element selected from oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, or boron.
  • the surface-metalized polymer article may be selected from a faucet, a shower head, a tubing, a pipe, a connector, an adaptor, a sink (e.g. kitchen or bathroom sink), a bathtub cover, a spout, a sink cover, a bathroom accessory, or a kitchen accessory.
  • a sink e.g. kitchen or bathroom sink
  • a bathtub cover e.g. a spout, a sink cover, a bathroom accessory, or a kitchen accessory.
  • the polymer component may contain a plastic, a rubber, a thermoplastic elastomer, a polymer matrix composite, a rubber matrix composite, or a combination thereof.
  • the polymer component contains a thermoplastic, a thermoset resin, an interpenetrating network, a rubber, a thermoplastic elastomer, a natural polymer, or a combination thereof.
  • the polymer component contains a plastic selected from acrylonitrile-butadiene- styrene copolymer (ABS), styrene-acrylonitrile copolymer (SAN), polycarbonate, polyamide or nylon, polystyrene, polyacrylate, polyethylene, polypropylene, polyacetal, polyester, polyether, polyether sulfone, poly ether ether ketone (PEEK), poly sulfone, polyphenylene oxide (PPO), polyvinyl chloride (PVC), polyimide, polyamide imide, polyurethane, polyurea, or a combination thereof.
  • ABS acrylonitrile-butadiene- styrene copolymer
  • SAN styrene-acrylonitrile copolymer
  • PES polycarbonate
  • polyamide or nylon polystyrene
  • polyacrylate polyethylene
  • polypropylene polyacetal
  • polyester polyether
  • PEEK polyether sul
  • the plated metal is preferably selected from copper, nickel, aluminum, chromium, tin, zinc, titanium, silver, gold, an alloy thereof, or a combination thereof.
  • the graphene sheets may be further decorated with nanoscaled particles or coating (having a diameter or thickness from 0.5 nm to 100 nm) of a catalytic metal selected from cobalt, nickel, copper, iron, manganese, tin, zinc, lead, bismuth, silver, gold, palladium, platinum, an alloy thereof, or a combination thereof, and wherein the catalytic metal is different in chemical composition than the plated metal.
  • a catalytic metal particles or coating are covered by at least a layer of plated metal
  • the polymer component surface prior to being deposited with the first layer of graphene sheets, contains only small openings or pores having a diameter or a depth ⁇ 0.1 pm.
  • the multiple graphene sheets are bonded to the polymer component surface with an adhesive resin having an adhesive-to-graphene weight ratio from 1/5000 to 1/10, preferably from 1/1000 to 1/100.
  • MCMB meocarbon microbeads
  • This material has a density of about 2.24 g/cm with a median particle size of about 16 pm.
  • MCMBs (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 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 neutral.
  • the slurry was dried and stored in a vacuum oven at 60°C for 24 hours.
  • the dried powder sample was placed in a quartz tube and inserted into a horizontal tube furnace pre-set at a desired temperature, 800°C-l,l00°C for 30-90 seconds to obtain graphene sheets.
  • a quantity of graphene sheets was mixed with water and ultrasonicated at 60-W power for 10 minutes to obtain a graphene dispersion.
  • the oxygen content of the graphene powders (GO or RGO) produced was from 0.1% to approximately 25%, depending upon the exfoliation temperature and time.
  • Graphite oxide was prepared by oxidation of graphite flakes with sulfuric acid, sodium nitrate, and potassium permanganate at a ratio of 4:1:0.05 at 30°C for 48 hours, according to the method of Hummers [US Pat. No.2, 798, 878, July 9, 1957].
  • the mixture was poured into deionized water and filtered.
  • the sample was then washed with 5% HC1 solution to remove most of the sulfate ions and residual salt and then repeatedly rinsed with deionized water until the pH of the filtrate was approximately 4.
  • the intent was to remove all sulfuric and nitric acid residue out of graphite interstices.
  • the slurry was dried and stored in a vacuum oven at 60°C for 24 hours.
  • the dried, intercalated (oxidized) compound was exfoliated by placing the sample in a quartz tube that was inserted into a horizontal tube furnace pre-set at l,050°C to obtain highly exfoliated graphite.
  • the exfoliated graphite was dispersed in water along with a 1% surfactant at 45°C in a flat-bottomed flask and the resulting suspension was subjected to ultrasonication for a period of 15 minutes to obtain dispersion of graphene oxide (GO) sheets.
  • EXAMPLE 3 Preparation of Pristine Graphene
  • Pristine graphene sheets were produced by using the direct ultrasonic ation or liquid-phase exfoliation process. In a typical procedure, five grams of graphite flakes, ground to
  • HEG highly exfoliated graphite
  • FHEG fluorinated highly exfoliated graphite
  • a pre-cooled Teflon reactor was filled with 20-30 mL of liquid pre-cooled ClF 3 , and then the reactor was closed and cooled to liquid nitrogen temperature. Subsequently, no more than 1 g of HEG was put in a container with holes for ClF 3 gas to access the reactor. After 7-10 days, a gray-beige product with approximate formula C 2 F was formed. GF sheets were then dispersed in halogenated solvents to form suspensions.
  • 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 N-l, N-2 and N-3 respectively and the nitrogen contents of these samples were 14.7, 18.2 and 17.5 wt.%
  • EXAMPLE 6 Graphene-Bonded/ Activated ABS A first set of several rectangular bars of ABS plastic each having a surface of 50 cm were immersed for 3 minutes at 70°C in an etching solution consisting of 4 M H 2 S0 4 and 3.5 M CrQ . The bars were rinsed with water. On a separate basis, a second set of several bars of identical dimensions were used without etching.
  • a first set of several rectangular bars of ABS plastic each having a surface of 50 cnrf were immersed for 3 minutes at 70°C in an etching solution consisting of 4 M H 2 S0 4 and 3.5 M Cr0 3 .
  • the bars were rinsed with water.
  • a second set of several bars of identical dimensions were used without etching.
  • the two sets of specimens were immersed for a time period of 5 minutes at 40°C in a Pd/Sn colloid-containing solution which contains 250 mg/L palladium 10 g/L tin(II) and 110 g/L HO. Subsequently, the specimens were rinsed in water and copper-plated in a sulfuric acid- containing copper electrolyte.
  • a Pd/Sn colloid-containing solution which contains 250 mg/L palladium 10 g/L tin(II) and 110 g/L HO.
  • the specimens were rinsed in water and copper-plated in a sulfuric acid- containing copper electrolyte.
  • ABS plastic surfaces could not be properly (evenly) metallized even when some significant amount of expensive rare metal (e.g. Pd) was implemented on etched surfaces.
  • a first set of several rectangular bars of HIPS plastic each having a surface of 50 cm 2 were immersed for 3 minutes at 70°C in an etching solution consisting of 4 M H 2 S0 4 and 3.5 M Cr(3 ⁇ 4. The bars were rinsed with water. On a separate basis, a second set of several bars of identical dimensions were used without etching.
  • the plastic articles were spray-coated with a pristine graphene-adhesive solution containing 5% by weight graphene sheets and 0.01% by weight epoxy resin. Upon removal of the liquid medium (acetone) and cured at 150°C for 15 minutes, graphene sheets were well bonded to plastic surfaces.
  • the graphene -bonded plastic articles were subjected to electro chemical nickel plating.
  • the articles were treated for 15 minutes in a Watts electrolyte, containing 1.2 M NiS0 4 .7H 2 0, 0.2 M NiCl 2 .6H 2Q and 0.5 M H3BO3.
  • the initial current was 0.3 A/dm 2 , and the nickel plating was earned out at 4Q°C.
  • a first set of several rectangular bars of HIPS plastic each having a surface of 50 cm were immersed for 3 minutes at 70°C in an etching solution consisting of 4 M H2SO4 and 3.5 M Cr0 3 .
  • the bars were rinsed with water.
  • a second set of several bars of identical dimensions were used without etching.
  • the plastic articles were treated for 30 seconds in an ammonia solution with 0.5 M CuS0 4 .5 H 2 0 having a pH value of 9.5 and a temperature of 20°C.
  • the plastic articles then were submerged for 20 seconds in distilled water and, subsequently, for 30 seconds treated with a sulfide solution, containing 0.1 M Na 2 S 2 at 20°C.
  • the plastic articles were again washed in cold water. This was followed by electro-chemical nickel plating. For this, the articles were treated for 15 minutes in a Watts electrolyte, containing 1.2 M
  • the initial current was 0.3 A/dm 2 , and the nickel plating was carried out at 40°C.
  • HIPS plastic surfaces could not be evenly metallized using the sulfide seeding approach.
  • the instant graphene-mediation approach enables successful plating of practically all kinds of metals on not just HIPS surfaces but any other types of polymer surfaces.
  • EXAMPLE 8 Graphene-Enabled Polyurethane-Based Thermoplastic Elastomer (TPE)
  • TPE bars were immersed in an aqueous alkaline solution containing 5 g/L sodium hydroxide and 0.5 g/L of GO for 15 minutes. The bars were then removed from the solution (actually a graphene dispersion), enabling graphene oxide sheets to get coated onto TPE surfaces while water was removed. Residual NaOH was rinsed away by water.
  • the GO-coated bars were subjected to electroless plating of nickel in an ammonia- containing nickel electrolyte at 30°C for 10 minutes.
  • Ni layer was directly deposited electrochemically onto GO-coated TPE surfaces. Both approaches were found to provide Ni layers that have high hardness, scratch resistance, and glossiness. This elegantly simple 2-step process is surprisingly effective in providing a wide variety of metallized polymer articles.
  • the TPE parts could not be uniformly metallized with the assistance of Pd/Sn catalyst seeds if without using strong chromo sulfuric acid as an etchant to produce large-sized microcavems (surface cavities) deeper than 0.3 pm.
  • This Pd/Sn catalyst was deposited onto large surface cavities of TPE after immersing etched TPE specimens in a Pd/Sn colloid-containing solution which contains 80 mg/L palladium, 10 g/L tin(II) and 110 g/L HC1 at 30°C for 10 minutes.
  • Catalytic metal can be deposited onto graphene surfaces using a variety of processes: physical vapor deposition, sputtering, chemical vapor deposition, chemical reduction/oxidation, electrochemical reduction/oxidation, etc.
  • Co is used as a representative catalytic metal and chemical oxidation/reduction from solution is used for deposition of nanoparticles on graphene surfaces.
  • a cobalt salt solution was used as the metal salt solution.
  • the aqueous cobalt (II) salt solution contains 1 to 10 g/L C0SO4.7H2O and one oxidizer, hydrogen peroxide.
  • Graphene oxide sheets were dispersed in the solution to form a dispersion. Heating of such a dispersion enabled at least part of the cobalt (II) to be oxidized by H 2 0 2 into cobalt (III), which was deposited on graphene surfaces upon further heating.
  • the electrolytic direct metallization of the composite surface was then allowed to proceed.
  • the composite surface was plated in a nickel bath, wherein an initial current density of 0.3 A/dm was used for electro -chemical nickel plating which later was increased to 3 A/dm .
  • Electro-chemical nickel plating was conducted in a Watts electrolyte at 30°C to 40°C for a treatment time of 10 to 15 minutes.
  • the Watts electrolyte contains 1.2 M NiS0 4 .7H 2 0, 0.2 M NiCl 2 .6H 2 0 and 0.5 M H3BO3.
  • EXAMPLE 10 Functionalized Graphene- and CNT-Bonded Poly Ether Ether Ketone (PEEK) and Other Polymer Components
  • PEEK Poly Ether Ether Ketone
  • a first set of several rectangular bars of PEEK plastic each having a surface of 50 caf were immersed for 3 minutes at 70°C in an etching solution consisting of 4 M H 2 S0 4 and 3.5 M CrQ . The bars were rinsed with water. Separately, a second set of several bars of identical dimensions were used without etching.
  • the graphene- and CNT-bonded plastic articles were subjected to chemical nickel plating or chemical copper plating.
  • nickel plating the functionalized graphene- and CNT-bonded articles were treated for 15 minutes in a chemical plating solution containing 1.2 M NiS0 4 -7H 2 0 at 40°C.
  • Cu plating the functionalized graphene- and CNT- bonded plastic parts were dipped in an ammonia solution with 0.5 M CuS0 4 , 5 3 ⁇ 40 having a pH value of 9.5 and a temperature of 20°C for 30 seconds.
  • the polymer components can be well-metallized using the presently disclosed functionalized graphene mediation approach even without an etching treatment.
  • metal was well-bonded to polymer component surfaces having excellent matte appearance and outstanding scratching resistance.
  • the metallized surfaces are generally smoother if functionalized graphene sheet s are included alone or in combinations with functionalized CNTs as compared to the use of functionalized CNTs alone in the dipping dispersion.
  • EXAMPLE 11 Graphene/Conductive Additive-Bonded Poly Ether Sulfone (PES) and Other Polymer Components
  • a first set of several rectangular bars of PES plastic each having a surface of 50 cn were immersed for 3 minutes at 70°C in an etching solution consisting of 4 M H 2 SO 4 and 3.5 M Cr0 3 .
  • the bars were rinsed with water.
  • a second set of several bars of identical dimensions were used without etching.
  • the plastic articles were dipped into a graphene/conductive filler/adhesive dispersion containing 5% by weight of graphene sheets, 0.5% by weight vapor-grown carbon nanofibers, and 0.01% by weight of epoxy resin or polyurethane.
  • Cu nanowires and Ni-coated polyacrylonitrile nanofibers were also used as a conductive filler in this example.
  • Chemical functional groups involved in this study include alkyl silane, hydroxyl group, carboxyl group, amine group, and diethylenetriamine (DETA). These functionalized graphene sheets are supplied from Taiwan Graphene Co., Taipei, Taiwan. Upon removal of the liquid medium (acetone) and cured at 150°C for 15 minutes, graphene sheets were well bonded to plastic surfaces.
  • the graphene/conductive filler-bonded plastic articles were subjected to chemical nickel plating or chemical copper plating.
  • nickel plating the bonded or covered polymer components were treated for 15 minutes in a chemical plating solution containing 1.2 M NiS0 4 -7H 2 0 at 40°C.
  • Cu plating the bonded or covered plastic parts were dipped in an ammonia solution with 0.5 M CuSCC , 5 3 ⁇ 40 having a pH value of 9.5 and a temperature of 20°C for 30 seconds.
  • the polymer components can be well-metallized using the presently disclosed functionalized graphene mediation approach even without an etching treatment.
  • metal was well-bonded to polymer component surfaces having excellent matte appearance and outstanding scratching resistance.
  • the metallized surfaces are generally smoother if graphene sheets are included alone or in combinations with a conductive filler as compared to the use of the conductive filler alone in the dipping dispersion.
  • a wide variety of chemical functional groups can be attached to the edges or surfaces of mediating graphene sheets or carbon nanotubes that enable rapid metallization of polymer components.
  • the disclosed process can be conducted under very mild conditions requiring only a short period of time. Optimal results are also achievable without the repetition of the process steps commonly required of prior art processes.
  • the process can be controlled in a functionally secure and simple manner which ultimately affects the quality of the metal layers.

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Abstract

L'invention concerne un appareil de fabrication d'un article polymère métallisé en surface, l'appareil comprenant: (a) une chambre de dépôt de graphène qui reçoit une dispersion de graphène comprenant de multiples feuilles de graphène et une charge conductrice facultative dispersée dans un premier milieu liquide et une résine adhésive facultative dissoute dans le premier milieu liquide, la chambre de dépôt de graphène étant actionnée pour déposer les feuilles de graphène et la charge conductrice facultative sur une surface d'au moins un composant polymère pour former au moins un composant polymère revêtu de graphène; et (b) une chambre de métallisation qui reçoit une solution de placage pour le placage d'une couche d'un métal souhaité sur le ou les composants polymères revêtus de graphène pour obtenir l'article polymère métallisé en surface.
PCT/US2018/061421 2018-03-19 2018-11-16 Appareil pour la production au graphène d'articles polymères métallisés WO2019182652A1 (fr)

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Citations (4)

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US20170194105A1 (en) * 2016-01-04 2017-07-06 Aruna Zhamu Supercapacitor having an integral 3D graphene-carbon hybrid foam-based electrode
US20170352869A1 (en) * 2016-06-07 2017-12-07 Nanotek Instruments, Inc. Graphene-Metal Hybrid Foam-Based Electrode for an Alkali Metal Battery
US20180130569A1 (en) * 2016-11-08 2018-05-10 The Regents Of The University Of California Graphene-polymer nanocomposites incorporating chemically doped graphene-polymer heterostructure for flexible and transparent conducting films

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US20110014492A1 (en) * 2008-03-13 2011-01-20 Basf Se Method and dispersion for applying a metal layer to a substrate and metallizable thermoplastic molding compound
US20170194105A1 (en) * 2016-01-04 2017-07-06 Aruna Zhamu Supercapacitor having an integral 3D graphene-carbon hybrid foam-based electrode
US20170352869A1 (en) * 2016-06-07 2017-12-07 Nanotek Instruments, Inc. Graphene-Metal Hybrid Foam-Based Electrode for an Alkali Metal Battery
US20180130569A1 (en) * 2016-11-08 2018-05-10 The Regents Of The University Of California Graphene-polymer nanocomposites incorporating chemically doped graphene-polymer heterostructure for flexible and transparent conducting films

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