EP4747437A1 - Fiber materials, fabrication methods and applications of same - Google Patents

Fiber materials, fabrication methods and applications of same

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Publication number
EP4747437A1
EP4747437A1 EP24846317.6A EP24846317A EP4747437A1 EP 4747437 A1 EP4747437 A1 EP 4747437A1 EP 24846317 A EP24846317 A EP 24846317A EP 4747437 A1 EP4747437 A1 EP 4747437A1
Authority
EP
European Patent Office
Prior art keywords
preformed
exchange
polymer
membrane
anion
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
EP24846317.6A
Other languages
German (de)
French (fr)
Inventor
Peter N. Pintauro
Ryszard J. Wycisk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vanderbilt University
Original Assignee
Vanderbilt University
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.)
Filing date
Publication date
Application filed by Vanderbilt University filed Critical Vanderbilt University
Publication of EP4747437A1 publication Critical patent/EP4747437A1/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0004—Organic membrane manufacture by agglomeration of particles
    • B01D67/00042—Organic membrane manufacture by agglomeration of particles by deposition of fibres, nanofibres or nanofibrils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/14—Dynamic membranes
    • B01D69/141—Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
    • B01D69/148—Organic/inorganic mixed matrix membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/36—Polytetrafluoroethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/52—Polyethers
    • B01D71/521—Aliphatic polyethers
    • B01D71/5211—Polyethylene glycol or polyethyleneoxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/76—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
    • B01D71/82—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1027—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having carbon, oxygen and other atoms, e.g. sulfonated polyethersulfones [S-PES]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/103—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1032—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having sulfur, e.g. sulfonated-polyethersulfones [S-PES]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1046—Mixtures of at least one polymer and at least one additive
    • H01M8/1051—Non-ion-conducting additives, e.g. stabilisers, SiO2 or ZrO2
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1053—Polymer electrolyte composites, mixtures or blends consisting of layers of polymers with at least one layer being ionically conductive
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1067—Polymeric electrolyte materials characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1069—Polymeric electrolyte materials characterised by the manufacturing processes
    • H01M8/1081—Polymeric electrolyte materials characterised by the manufacturing processes starting from solutions, dispersions or slurries exclusively of polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/30—Cross-linking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/42—Ion-exchange membranes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
    • H01M8/184—Regeneration by electrochemical means
    • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/22—Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
    • H01M8/227—Dialytic cells or batteries; Reverse electrodialysis cells or batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
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  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Composite Materials (AREA)
  • Dispersion Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Nanotechnology (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

A method of fabricating a membrane comprises dispersing preformed polymer nanofibers in at least one first solvent to form a dispersion; spraying or coating the dispersion on a surface of a substrate to form a nanofiber-based structure thereon; and evaporating the at least one first solvent from the nanofiber-based structure to form the membrane therewith, where the membrane has porosity.

Description

FIBER MATERIALS, FABRICATION METHODS AND APPLICATIONS OF SAME
STATEMENT AS TO RIGHTS UNDER FEDERALLY-SPONSORED RESEARCH
This invention was made with government support under Contract Nos. DE- EE0007215, DE-EE0008418, and DE-AR000103, awarded by the Department of Energy. The government has certain rights in the invention.
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
This application claims priority to and the benefit of U.S. provisional patent application No. 63/528,092, filed July 21, 2023.
This application also is a continuation-in-part application of U.S. patent application No. 17/341,487, filed June 8, 2021, which itself claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 63/035,918, filed June 8, 2020.
This application also is a continuation-in-part application of U.S. patent application No 18/567,888, filed December 7, 2023, which a U.S. national phase application of PCT Patent Application No. PCT/US2021/061967, filed December 6, 2021, which is a continuation in part of, and claims priority to and the benefit of U.S. Patent Application Serial No. 17/341,487, filed June 8, 2021, which itself claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 63/035,918, filed June 8, 2020.
All of the above-identified disclosures are incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
The invention relates generally to materials, and more particularly, to the production and use of charged polymer fibers and particle/polymer fibers made by electrospinning, or certain methods that do not require the use of an applied electric field, such as centrifugal spinning or gas-jet spinning, where the resulting fibers are dispersed in a solvent or polymer solution or polymer melt, and then formed into a thin film.
BACKGROUND OF THE INVENTION
Normally a mat or bundle of polymer or polymer/particle nanofibers is used directly in a device. For example, porous nanofiber polymer mats are used as microfiltration membranes and filters and fiber mat bundles are used as tissue engineering scaffolds. However, to date no one has reported on the redispersion of one or more fiber mats or fiber bundles into a solvent, polymer solution, or polymer melt followed by the formation of a thin film from the dispersion by a spraying or coating method.
SUMMARY OF THE INVENTION
This invention described herein is particularly relevant to centrifugal fiber spinning and gas-jet fiber spinning, where a bundle of nanofibers is created during the spinning process. Conventionally, a thick fiber bundle cannot be used directly to produce a thin layer (mat) of nanofibers, where the mat thickness is on the order of 25- 150 microns. The invention, among other things, overcomes this limitation.
In one aspect, the invention deals with the methods of fabrication of composite monopolar or three-dimension (3D) junction bipolar membranes containing one or more different types of preformed nanofibers. The nanofibers are composed of one or more polymers, or one or more polymers plus one or more types of particles. The nanofibers are spread into a thin film by a spraying or coating method. The nanofibers are preproduced by an electrospinning process or a nanofiber spinning process that does not require an electric field, such as centrifugal spinning or gas-jet spinning [1-4], Thus, the subject matter of this invention deals with polymer and particle/polymer fibers, the methods of making such fibers, the distribution of the fibers into a thin mat/layer, the use of such fibers in making membranes, and the use of such membranes in a device or process.
The coating or spraying of a dispersion of preformed nanofibers produces a porous film after solvent evaporation. The interfiber void space can be eliminated or significantly reduced by compressive pressure, heat, or exposure to a liquid or vapor solvent, or some combination thereof, resulting in a dense membrane.
In one embodiment, the method of fabricating a membrane comprises dispersing preformed polymer nanofibers in at least one first solvent to form a dispersion; spraying or coating the dispersion on a surface of a substrate to form a nanofiber-based structure thereon; and evaporating the at least one first solvent from the nanofiber-based structure to form the membrane therewith, wherein the membrane has porosity.
In one embodiment, the method further comprises, prior to said spraying or coating step, adding nanoparticles to the dispersion.
In one embodiment, the substate upon which the dispersion of preformed nanofibers is sprayed or coated is a preformed polymer film.
In one embodiment, the membrane is a porous nanofiber mat.
In one embodiment, the preformed polymer nanofibers comprise one or more types of preformed charged anion-exchange or cation-exchange polymer nanofibers; and the method further comprises impregnating an uncharged polymer solution containing one or more types of uncharged polymers dispersed in at least one second solvent into the porous nanofiber mat; and evaporating the at least one second solvent from the impregnated porous nanofiber mat, thereby forming a nanofiber-based anion-exchange or cation-exchange membrane.
In one embodiment, the preformed polymer nanofibers comprise one or more types of preformed uncharged polymer nanofibers; and the method further comprises forming a thin porous film by spraying or coating the dispersion on a surface and allowing the solvent to evaporate followed by impregnating a cation-exchange polymer or anion-exchange polymer solution containing one or more types of cation-exchange polymers or anion-exchange polymers dispersed in at least one third solvent into the porous nanofiber mat; and evaporating the at least one third solvent from the impregnated porous nanofiber mat, thereby forming a nanofiber-based anion-exchange or cation-exchange membrane.
In one embodiment, the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or fiber-reinforce anion-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce cation-exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the preformed polymer nanofibers comprise one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or fiber-reinforce cation-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce anion-exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films. In one embodiment, the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers and one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or fiber-reinforce anion-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce cationexchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers and one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or fiber-reinforce cation-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce anion- exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the charged and/or uncharged polymer nanofibers comprise hydrocarbon polymers.
In one embodiment, the uncharged polymer nanofibers comprise polysulfone, polyethersulfone, polyamide imide, poly (vinylidene fluoride) and/or polyphenylene oxide.
In one embodiment, the charged polymer nanofibers comprise cation-exchange and/or anion-exchange polymers.
In one embodiment, the cation-exchange polymers have sulfonate or carboxylate cation-exchange groups.
In one embodiment, the charged polymer nanofibers comprise sulfonated poly(ether ether ketone), sulfonated polysulfone, sulfonated polyphenylene oxide, sulfonated poly(ether sulfone), or sulfonated poly(arylene ether sulfone) cationexchange sites.
In one embodiment, the anion-exchange polymers have tetraalkyl am monium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium anion- exchange groups.
In one embodiment, the charged and/or uncharged polymer nanofibers comprise fluoropolymers.
In one embodiment, the cation-exchange polymer nanofibers comprise a fluoropolymer with sulfonic acid ion-exchange sites.
In one embodiment, said one or more types of preformed charged and/or uncharged polymer nanofibers are crosslinked.
In one embodiment, said one or more types of preformed charged and/or uncharged polymer nanofibers contain nanoparticles.
In one embodiment, the nanoparticles are one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
In one embodiment, the preformed polymer nanofibers are preformed before preparation of the dispersion by a method that does not employ an electric field.
In one embodiment, the preformed polymer nanofibers are made using a centrifugal spinning method or gas jet spinning method.
In one embodiment, the preformed polymer nanofibers comprise two or more different types of polymer nanofibers that are fabricated simultaneously during the spinning process.
In one embodiment, the preformed polymer nanofibers are fabricated with a spinning solution containing a charged or uncharged polymer and a carrier polymer.
In one embodiment, the carrier polymer comprises poly(ethylene oxide), polyvinyl pyrrolidone, or poly(acrylic acid).
In one embodiment, the dispersion of one or more preformed nanofibers contains nanoparticles suspended in the dispersion solvent.
In one embodiment, the nanoparticles suspended in the dispersion solvent are one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
In certain aspects, the invention also relates to a cation-exchange or anion-exchange membrane, and/or a bipolar membrane, made by the above disclosed methods.
In other aspects, the invention further relates to an electrochemical device, and/or an electrodialysis cell, comprising one or more monopolar cation and anion-exchange membranes and/or bipolar membranes, made by the above disclosed methods.
In another aspect of the invention, a membrane comprises a network of preformed polymer nanofibers, wherein the preformed polymer nanofibers comprise one or more types of preformed uncharged polymer nanofibers, one or more types of preformed charged polymer nanofibers, or a combination of them.
In one embodiment, the preformed polymer nanofibers comprise nanoparticles.
In one embodiment, the network of preformed polymer nanofibers is formed by spraying or coating a dispersion comprising the preformed polymer nanofibers in at least one first solvent on a surface of a substrate, followed by solvent evaporation.
In one embodiment, the preformed polymer nanofibers comprise said one or more types of preformed charged polymer nanofibers; and the membrane further comprises an unchanged polymer impregnated into the network of preformed polymer nanofibers, whereby the membrane is a nanofiber-based anion-exchange or cation-exchange membrane.
In one embodiment, the preformed polymer nanofibers comprise said one or more types of preformed uncharged polymer nanofibers; and the membrane further comprises a cation-exchange polymer or anion-exchange polymer impregnated into the network of preformed polymer nanofibers, whereby the membrane is a nanofiber-based anion- exchange or cation-exchange membrane.
In one embodiment, the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; and the membrane further comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the preformed polymer nanofibers comprise said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; and the membrane further comprises a preformed dense homogeneous or nanofiber- reinforce anion-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers and said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; and the membrane further comprises hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers and said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; and the membrane further comprises a preformed dense homogeneous or nanofiber-reinforce anion- exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In one embodiment, the charged and/or uncharged polymer nanofibers comprise hydrocarbon polymers.
In one embodiment, the uncharged polymer nanofibers comprise polysulfone, polyethersulfone, polyamide imide, poly(vinylidene fluoride) and/or polyphenylene oxide.
In one embodiment, the charged polymer nanofibers comprise cation-exchange and/or anion-exchange polymers.
In one embodiment, the cation-exchange polymers have sulfonate or carboxylate cation-exchange groups.
In one embodiment, the charged polymer nanofibers comprise sulfonated poly(ether ether ketone), sulfonated polysulfone, sulfonated polyphenylene oxide, sulfonated poly(ether sulfone), or sulfonated (polyarylene ether sulfone) cationexchange sites.
In one embodiment, the anion-exchange polymers have benzyltrialkylammonium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium, quaternary ammonium, or benzyldimethylhexylammonium anion-exchange groups.
In one embodiment, the charged and/or uncharged polymer nanofibers comprise fluoropolymers. In one embodiment, the cation-exchange polymer nanofibers comprise a fluoropolymer with sulfonic acid ion-exchange sites.
In one embodiment, said one or more types of preformed charged and/or uncharged polymer nanofibers are crosslinked.
In one embodiment, said one or more types of preformed charged and/or uncharged polymer nanofibers contain nanoparticles.
In one embodiment, the nanoparticles are one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
In one embodiment, the preformed polymer nanofibers are preformed before preparation of the dispersion by a method that does not employ an electric field.
In one embodiment, the preformed polymer nanofibers are made using a centrifugal spinning method or gas jet spinning method.
In one embodiment, the preformed polymer nanofibers comprise two or more different types of polymer nanofibers that are fabricated simultaneously during the spinning process.
In one embodiment, the preformed polymer nanofibers are fabricated with a spinning solution containing a charged or uncharged polymer and a carrier polymer.
In one embodiment, the carrier polymer comprises poly(ethylene oxide), polyvinyl pyrrolidone, or poly(acrylic acid).
In one embodiment, two or more dispersions each comprising different preformed polymer or polymer/particle nanofibers are used to create a layered porous, semi-porous, or dense membrane, by the sequential and/or repeated deposition of the dispersions by a spraying or coating method, followed by a suitable method to close some or all of the void space between the deposited fibers. Dispersions A and B can be deposited multiple times to produce a membrane with a repeated ABABAB layered composition. Similarly, dispersions A, B, C, and D can be deposited to form a membrane with a layered composition of ABCD or ABCABCD or CDABABABDC. The multiple layers can be deposited on preformed polymeric anion-exchange or cation-exchange membrane or an inert substrate that is removed from the final membrane.
In certain embodiments, the solvent contains a single component solvent or a mixture of two or more liquids.
These and other aspects of the invention will become apparent from the following description of the preferred embodiments, taken in conjunction with the following drawings, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate one or more embodiments of the invention and, together with the written description, serve to explain the principles of the invention. The same reference numbers may be used throughout the drawings to refer to the same or like elements in the embodiments.
FIG. 1 shows scanning Electron Microscope (SEM) images of electrospun polymer fibers and fibers made by centrifugal spinning, according to embodiments of the invention. The fibers are composed of perfluorosulfonic acid cation-exchange polymer and polyethylene oxide.
FIG. 2 shows SEM images of polymer/particle fibers at different magnifications, where the fibers were made by centrifugal spinning, according to embodiments of the invention. The fibers are composed of perfluorosulfonic acid cation-exchange and polyethylene oxide with Fe- N-C catalyst particles.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.
The terms used in this specification generally have their ordinary meanings in the art, within the context of the invention, and in the specific context where each term is used. Certain terms that are used to describe the invention are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the invention. For convenience, certain terms may be highlighted, for example using italics and/or quotation marks. The use of highlighting has no influence on the scope and meaning of a term; the scope and meaning of a term is the same, in the same context, whether or not it is highlighted. It will be appreciated that same thing can be said in more than one way. Consequently, alternative language and synonyms may be used for any one or more of the terms discussed herein, nor is any special significance to be placed upon whether or not a term is elaborated or discussed herein. Synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope and meaning of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification.
It will be understood that, as used in the description herein and throughout the claims that follow, the meaning of "a", "an", and "the" includes plural reference unless the context clearly dictates otherwise. Also, it will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the invention.
Furthermore, relative terms, such as "lower" or "bottom" and "upper" or "top," may be used herein to describe one element's relationship to another element as illustrated in the figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. The exemplary term "lower", can therefore, encompasses both an orientation of "lower" and "upper," depending of the particular orientation of the figure. Similarly, if the device in one of the figures, is turned over, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. The exemplary terms "below" or "beneath" can, therefore, encompass both an orientation of above and below.
It will be further understood that the terms "comprises" and/or "comprising," or "includes" and/or "including" or "has" and/or "having", or "carry" and/or "carrying," or "contain" and/or "containing," or "involve" and/or "involving, and the like are to be open-ended, i.e., to mean including but not limited to. When used in this invention, they specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
As used herein, "around", "about" or "approximately" shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term "around", "about" or "approximately" can be inferred if not expressly stated.
As used herein, the terms "comprise" or "comprising", "include" or "including", "carry" or "carrying", "has/have" or "having", "contain" or "containing", "involve" or "involving" and the like are to be understood to be open-ended, i.e., to mean including but not limited to.
As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C), using a non-exclusive logical OR. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the invention.
The description below is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. The broad teachings of the invention can be implemented in a variety of forms. Therefore, while this invention includes particular examples, the true scope of the invention should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the invention.
In one aspect, the invention relates to the creation of a porous nanofiber mat using preformed fibers made by electrospinning, centrifugal spinning, gas-jet spinning, or some other method of making nanofibers that does not involve an electric field. The nanofibers may be composed of uncharged polymers or an ion-exchange polymer (either a cation-exchange polymer or an anion-exchange polymer). One or more types of preformed fibers are dispersed in a suitable solvent, such as a water/alcohol solvent, with optionally the addition of a surfactant to assist in creating or stabilizing the dispersion. The fiber-containing dispersion is then coated on a surface, by spraying the dispersion or by using a liquid coating method, e.g., slot-die, wire rod, gravure, spin coat, or knife edge. The surface could be an inert polymer film, an inert nonwoven fabric, or a polymer that become part of the final membrane, such as a cation-exchange polymer film or an anion-exchange polymer film. Sufficient solution is deposited so that a porous nanofiber mat of finite thickness is created after solvent evaporation. A polymer solution can then be impregnated in the void space between the fibers. For uncharged polymer nanofibers, for example, a solution of an anion-exchange polymer or a solution of a cation-exchange polymer is impregnated between the uncharged fibers. After one or more impregnations and solvent evaporation steps, a dense composite membrane is produced, where the preformed nanofibers are dispersed in a cationexchange or anion-exchange polymer matrix.
In another aspect of the invention, preformed anion-exchange and/or cationexchange fibers are dispersed in a suitable solvent and then deposited onto a surface by spraying the solution or by a coating method. After solvent evaporation, an uncharged polymer solution is impregnated between the fibers. After one or more impregnations and solvent evaporation steps, a dense composite polymer membrane is formed, where anion-exchange and/or cation-exchange nanofibers are dispersed in an uncharged polymer matrix.
The preformed fibers may contain one or more different types of nanoparticles, or the impregnation solution may contain nanoparticles. Additionally, the fibers themselves may comprise two or more polymers and the impregnating solution may be comprised of two or more polymers.
In a further aspect of this invention, preformed uncharged polymer fibers are dispersed in an anion-exchange polymer or cation-exchange polymer solution, i.e., a solution of the anion-exchange polymer or cation-exchange polymer in a suitable organic solvent that will not dissolve the preformed nanofibers. To prevent nanofiber dissolution, the nanofibers may be optionally crosslinked. Alternatively, anion- exchange polymer droplets (micelles) or cation-exchange polymer droplets (micelles) can be dispersed with the preformed nanofibers in a solvent, such as a mixture of water and alcohol. The nanofiber dispersion is then sprayed or coated onto a surface and the solvent is allowed to evaporate, thus creating a composite membrane where uncharged fibers are dispersed in an ion-exchange polymer matrix. Similarly, one can disperse preformed ion-exchange polymer nanofibers in a solution of an uncharged or charged polymer, using a solvent that will dissolve the uncharged or charged polymer but not the anion-exchange or cation-exchange polymer fibers. The dispersion is then sprayed or coated on a surface and the solvent is allowed to evaporate, thus forming a composite membrane where ion-exchange fibers are dispersed in an uncharged polymer matrix. The surface on which the dispersion is sprayed or coated can be an inert polymer film, a nonwoven fabric, a previously deposited layer of preformed nanofibers, or a preformed polymer membrane.
In yet a further aspect of the invention, preformed anion and cation-exchange fibers are dispersed in a suitable solvent, with or without the addition of a surfactant, and with the addition of nanoparticles (e.g., TiC>2, AI2O3, nanodiamond, nanographene oxide, and/or Al(OH)s), where the weight fraction of anion-exchange fibers, cationexchange fibers, and nanoparticles is changeable. The mixture is sprayed or cast/coated on a flat surface, which may be a preformed dense anion-exchange membrane or cationexchange membrane. After deposition, and solvent evaporation, a second preformed dense film is place on the dual fiber deposited mat, where the second film has the opposite charge as the film on which the fibers were deposited. The entire three-layer construct is then hot pressed to melt one type of fiber in the center layer and to fuse the outer films to the center layer. The result is a bipolar membrane with a 3D junction layer of interlocking anion-exchange and cation-exchange fibers with attached outer layers, one layer being composted of anion-exchange polymer and the second outer layer being composted of cation-exchange polymer. The preformed outer dense layers may be composite ion-exchange membranes, i.e., membranes composted of anion- exchange polymer or cation-exchange polymer with dispersed nanofibers of an uncharged polymer. An example of this type of membrane is as follows: a dispersion of anion-exchange and cation-exchange fibers with TiCh nanoparticles is spray coated on a pre-existing dene film of anion-exchange polymer. A pre-existing cation-exchange polymer film is then placed on top of the spray fiber mat and all three layers are hot pressed. In a slightly modified method, a dispersion of preformed anion-exchange polymer fibers plus dispersed particles is spray coated onto a pre-existing dense anion- exchange membrane. A pre-existing dense cation-exchange membrane is then placed on top of the fiber layer and the entire construct is then hot pressed at a pressure and temperature that will allow the cation-exchange film to soften and flow between the preformed anion-exchange fibers, where the temperature and pressure are insufficient to destroy the spray-coated anion-exchange fiber network.
The charged polymer nanofibers are made by electrospinning a solution comprising an anion-exchange polymer or cation-exchange polymer or blends of two or more charged polymers. Optionally a carrier polymer can be added to the spinning solution. The apparatus to make the fibers maybe be an electrospinning apparatus, a centrifugal spinner, a gas-jet spinning apparatus, or spinning equipment that does not employ an electric field.
Without intent to limit the scope of the invention, exemplary embodiments of the invention are described below.
In some embodiments, the method of fabricating a membrane comprises dispersing preformed polymer nanofibers in at least one first solvent to form a dispersion; spraying or coating the dispersion on a surface of a substrate to form a nanofiber-based structure thereon; and evaporating the at least one first solvent from the nanofiber-based structure to form the membrane therewith, wherein the membrane has porosity.
In some embodiments, the method further comprises, prior to said spraying or coating step, adding nanoparticles to the dispersion.
In some embodiments, the membrane is a porous nanofiber mat.
In some embodiments, the preformed polymer nanofibers comprise one or more types of preformed charged anion-exchange or cation-exchange polymer nanofibers; and the method further comprises impregnating an uncharged polymer solution containing one or more types of uncharged polymers dispersed in at least one second solvent into the porous nanofiber mat; and evaporating the at least one second solvent from the impregnated porous nanofiber mat, thereby forming a nanofiber-based anion-exchange or cation-exchange membrane.
In some embodiments, the preformed polymer nanofibers comprise one or more types of preformed uncharged polymer nanofibers; and the method further comprises impregnating a cation-exchange polymer or anion-exchange polymer solution containing one or more types of cation-exchange polymers or anion-exchange polymers dispersed in at least one third solvent into the porous nanofiber mat; and evaporating the at least one third solvent from the impregnated porous nanofiber mat, thereby forming a nanofiber-based anion-exchange or cation-exchange membrane.
In some embodiments, the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber- reinforce cation-exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the preformed polymer nanofibers comprise one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce anion-exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers and one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce cationexchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films. In some embodiments, the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers and one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; and the method further comprises hot pressing a preformed dense homogeneous or nanofiber-reinforce anion- exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the charged and/or uncharged polymer nanofibers comprise hydrocarbon polymers.
In some embodiments, the uncharged polymer nanofibers comprise polysulfone, polyethersulfone, polyamide imide, poly (vinylidene fluoride) and/or polyphenylene oxide.
In some embodiments, the charged polymer nanofibers comprise cationexchange and/or anion-exchange polymers.
In some embodiments, the cation-exchange polymers have sulfonate or carboxylate cation-exchange groups.
In some embodiments, the charged polymer nanofibers comprise sulfonated poly(ether ether ketone), sulfonated polysulfone, sulfonated polyphenylene oxide, sulfonated poly(ether sulfone), or sulfonated (polyarylene ether sulfone) cationexchange sites.
In some embodiments, the anion-exchange polymers have benzyltrialkylammonium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium, quaternary ammonium, or benzyldimethylhexylammonium anion-exchange groups.
In some embodiments, the charged and/or uncharged polymer nanofibers comprise fluoropolymers.
In some embodiments, the cation-exchange polymer nanofibers comprise a fluoropolymer with sulfonic acid ion-exchange sites.
In some embodiments, said one or more types of preformed charged and/or uncharged polymer nanofibers are crosslinked.
In some embodiments, said one or more types of preformed charged and/or uncharged polymer nanofibers contain nanoparticles. In some embodiments, the nanoparticles are one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
In some embodiments, the preformed polymer nanofibers are preformed before preparation of the dispersion by a method that does not employ an electric field.
In some embodiments, the preformed polymer nanofibers are made using a centrifugal spinning method or gas jet spinning method.
In some embodiments, the preformed polymer nanofibers comprise two or more different types of polymer nanofibers that are fabricated simultaneously during the spinning process.
In some embodiments, the preformed polymer nanofibers are fabricated with a spinning solution containing a charged or uncharged polymer and a carrier polymer.
In some embodiments, the carrier polymer comprises poly(ethylene oxide), polyvinyl pyrrolidone, or poly(acrylic acid).
In some embodiments, the preformed nanofibers are dispersed in a solvent that also contains one or more types of suspended nanoparticle.
In some embodiments, the suspended nanoparticles comprise one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
In certain aspects, the invention also relates to a cation-exchange or anion-exchange membrane, and/or a bipolar membrane, made by the above disclosed methods.
In other aspects, the invention further relates to an electrochemical device, and/or an electrodialysis cell, comprising one or more monopolar cation and anion-exchange membranes and/or bipolar membranes, made by the above disclosed methods.
In another aspect of the invention, a membrane comprises a network of preformed polymer nanofibers, wherein the preformed polymer nanofibers comprise one or more types of preformed uncharged polymer nanofibers, one or more types of preformed charged polymer nanofibers, or a combination of them.
In some embodiments, the preformed polymer nanofibers comprise nanoparticles.
In some embodiments, the network of preformed polymer nanofibers is formed by spraying or coating a dispersion comprising the preformed polymer nanofibers in at least one first solvent on a surface of a substrate, followed by solvent evaporation.
In some embodiments, the preformed polymer nanofibers comprise said one or more types of preformed charged polymer nanofibers; and the membrane further comprises an unchanged polymer impregnated into the network of preformed polymer nanofibers, whereby the membrane is a nanofiber-based anion-exchange or cation-exchange membrane.
In some embodiments, the preformed polymer nanofibers comprise said one or more types of preformed uncharged polymer nanofibers; and the membrane further comprises a cation-exchange polymer or anion-exchange polymer impregnated into the network of preformed polymer nanofibers, whereby the membrane is a nanofiber-based anion- exchange or cation-exchange membrane.
In some embodiments, the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; and the membrane further comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the preformed polymer nanofibers comprise said one or more types of preformed cation- exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; and the membrane further comprises a preformed dense homogeneous or nanofiber- reinforce anion-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers and said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; and the membrane further comprises hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers and said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; and the membrane further comprises a preformed dense homogeneous or nanofiber-reinforce anion- exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
In some embodiments, the charged and/or uncharged polymer nanofibers comprise hydrocarbon polymers.
In some embodiments, the uncharged polymer nanofibers comprise polysulfone, polyethersulfone, polyamide imide, poly (vinylidene fluoride) and/or polyphenylene oxide.
In some embodiments, the charged polymer nanofibers comprise cationexchange and/or anion-exchange polymers.
In some embodiments, the cation-exchange polymers have sulfonate or carboxylate cation-exchange groups.
In some embodiments, the charged polymer nanofibers comprise sulfonated poly(ether ether ketone), sulfonated polysulfone, sulfonated polyphenylene oxide, sulfonated poly(ether sulfone), or sulfonated (polyarylene ether sulfone) cationexchange sites.
In some embodiments, the anion-exchange polymers have benzyltrialkylammonium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium, quaternary ammonium, or benzyldimethylhexylammonium anion-exchange groups.
In some embodiments, the charged and/or uncharged polymer nanofibers comprise fluoropolymers.
In some embodiments, the cation-exchange polymer nanofibers comprise a fluoropolymer with sulfonic acid ion-exchange sites.
In some embodiments, said one or more types of preformed charged and/or uncharged polymer nanofibers are crosslinked.
In some embodiments, said one or more types of preformed charged and/or uncharged polymer nanofibers contain nanoparticles.
In some embodiments, the nanoparticles are one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
In some embodiments, the preformed polymer nanofibers are preformed before preparation of the dispersion by a method that does not employ an electric field.
In some embodiments, the preformed polymer nanofibers are made using a centrifugal spinning method or gas jet spinning method.
In some embodiments, the preformed polymer nanofibers comprise two or more different types of polymer nanofibers that are fabricated simultaneously during the spinning process.
In some embodiments, the preformed polymer nanofibers are fabricated with a spinning solution containing a charged or uncharged polymer and a carrier polymer.
In some embodiments, the carrier polymer comprises poly(ethylene oxide), polyvinyl pyrrolidone, or poly(acrylic acid).
In some embodiments, two or more dispersions each comprising different preformed polymer or polymer/particle nanofibers are used to create a layered porous, semi-porous, or dense membrane, by the sequential and/or repeated deposition of the dispersions by a spraying or coating method, followed by a suitable method to close some or all of the void space between the deposited fibers. Dispersions A and B can be deposited multiple times to produce a membrane with a repeated ABABAB layered composition. Similarly, dispersions A, B, C, and D can be deposited to form a membrane with a layered composition of ABCD or ABCABCD or CDABABABDC. The multiple layers can be deposited on preformed polymeric anion-exchange or cation-exchange membrane or an inert substrate that is removed from the final membrane.
In some embodiments, one or more types of preformed uncharged nanofibers are dispersed in a solvent to form a solution/dispersion thereof. The solution is then spread into a thin layer by spraying the solution or by using a coating method, such as slot-die, wire rod, gravure, or knife edge. After evaporation of the solvent, a porous fiber layer containing a network of fibers is produced. The porous fiber layer can be directly used as a porous fiber membrane, or further processed by a hot-pressing step to eliminate the void space between fibers, thus producing a dense membrane.
In some embodiments, one or more types of preformed uncharged nanofibers are dispersed in a solvent containing solid nanoparticles and/or dispersed polymer particles/micelles to form a solution/dispersion thereof. The solution is then spread into a thin layer by spraying the solution or by using a coating method, such as slot-die, wire rod, gravure, or knife edge. After evaporation of the solvent, a porous fiber layer is produced. The porous layer can be further processed by a hot-pressing step to produce a dense membrane.
In some embodiments, one or more types of preformed uncharged polymer nanofibers are dispersed in a solution or dispersion of one or more charged polymers to form a polymer solution. Solid nanoparticle may optionally be added to the polymer solution. The polymer solution is then spread into a thin layer by spraying the solution or by using a coating method, such as slot-die, wire rod, gravure, or knife edge. After evaporation of the solvent, a porous fiber layer is produced. The porosity is then eliminated by a hot-pressing and/or solvent exposure step, resulting in a dense composite membrane with the nanofibers dispersed throughout the membrane polymer matrix.
In some embodiments, one or more types of preformed uncharged polymer nanofibers are dispersed in a polymer solution of one or more cation-exchange polymers or one or more anion-exchange polymers. The polymer solution is then spread into a thin layer by spraying the solution or by using a coating method, such as slot-die, wire rod, gravure, or knife edge. After evaporation of the solvent, a dense nanofiber composite cation-exchange or anion-exchange membrane is produced, where uncharged fibers are dispersed throughout the charged polymer film.
In some embodiments, one or more types of preformed cation-exchange fibers, one or more types of preformed anion-exchange nanofibers, or a mixture of the preformed cation-exchange fibers and the preformed anion-exchange nanofibers are dispersed in a polymer solution or a polymer dispersion of one or more uncharged polymers. The polymer solution is then spread into a thin layer by spraying the solution or by using a coating method, such as slot-die, wire rod, gravure, or knife edge. After evaporation of the solvent, a dense nanofiber composite cation-exchange or anion- exchange membrane is produced, where ion-exchange polymer nanofibers are dispersed throughout an uncharged polymer film.
In some embodiments, one or more types of preformed cation-exchange fibers, one or more types of preformed anion-exchange nanofibers, or a mixture of the preformed cation-exchange fibers and the preformed anion-exchange nanofibers are dispersed in a polymer solution or a polymer dispersion of one or more uncharged polymers and then formed into a thin film by a spraying or coating method. After solvent evaporation, the porous fiber layer is used as the 3D junction layer during the fabrication of a bipolar membrane. Additionally, the dispersion of cation-exchange and anion-exchange fibers may contains dispersed solid nanoparticles, where the nanoparticles include TiCh, AI2O3, nanodiamond, nanographene oxide, and/or Al(OH)s.
In some embodiments, the nanofibers are fabricated by electrospinning, centrifugal spinning, gas-jet spinning, or some other fiber spinning process that does utilize an electric field.
In some embodiments, two or more different nanofibers are fabricated simultaneously during the spinning process, using separate orifices/needles and polymer solutions for each fiber.
In some embodiments, the porous layer composed of cation-exchange and anion- exchange fibers, optionally with dispersed solid nanofibers is sandwiched between a dense cation-exchange membrane and a dense anion-exchange membrane and then hot pressed to create a three-layer bipolar membrane with a 3D nanofib er junction layer.
In some embodiments, the polymer solution for fiber spinning comprises a hydrocarbon polymer with fixed charge groups that is dissolved in a solvent, wherein the fixed charge groups are either positively charged or negatively charged.
In some embodiments, the polymer solution for fiber spinning comprises a hydrocarbon polymer with benzyltrialkylammonium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium, quaternary ammonium, or benzyl di methyl hexyl am monium anion-exchange groups.
In some embodiments, the anion-exchange polymer backbone comprises comprise poly(phenylene oxide), poly(ether sulfone), poly(arylene ether sulfone) or some other aromatic - ring -containing hydrocarbon polymer.
In some embodiments, the polymer solution for fiber spinning comprises a poly(phenylene oxide) polymer with benzyl tri alky lam monium positively charged ionexchange groups.
In some embodiments, the polymer solution for fiber spinning comprises a poly (phenylene oxide) polymer with benzyldimethylhexylammonium fixed charge groups.
In some embodiments, the polymer solution for fiber spinning comprises a hydrocarbon polymer with sulfonate or carboxylate negatively charged ion-exchange groups.
In some embodiments, the polymer solution for fiber spinning comprises a charged perfluorinated or hydrocarbon polymer and an uncharged carrier polymer such as polyethylene oxide, poly(acrylic acid), polyvinylidene fluoride, or polyvinyl pyrrolidone.
In some embodiments, the polymer solution contains a low boiling point solvent.
In some embodiments, the polymer solution contains two or more polymers.
In some embodiments, the one or more polymers within charged or uncharged fibers is crosslinked.
In some embodiments, solid particles are added to the polymer solution for fiber spinning, where such particles may include one or more of the following types: (1) a metal on a support, wherein the support comprises carbon, graphite, silica, alumina, titania, or an oxide material, and the metal comprises one or more platinum group metals (Pt, Pd, Ru, Ir, Rh, Os), platinum group metal alloys (PtCo or PtNi), silver (Ag) particles, Ag alloy particles, nickel (Ni) particles, Ni alloy particles, iron (Fe) particles, Fe alloy particles, or a combination thereof, (2) zeolites, (3) silica, (4) graphite, (5) a metal oxide, such as LiCoCM or lrO2, (6) a precious metal or alloy, e.g., Pt-black or PtRu-black, (7) a platinum-group- metal free (PGM-free) powder, wherein the PGM-free powder comprises metal -nitrogen moieties embedded in carbon (MNxCy), nitrogen-carbon moieties (CNx), nitrogen doped carbon encapsulating inorganic metal species (M@NxCy), or a combination thereof, (8) core-shell and shape controlled catalyst particles, and/or (9) one or more of the following particles: TiC>2, AI2O3, nanodiamond, nanographene oxide, and/or Al (OH)s.
In some embodiments, the fibers are used to make a bipolar membrane in a redox flow battery, a CO2 electrochemical reduction reactor, an electrodialysis cell or stack for acid and based production, or some other electrochemical device.
In the above embodiments, solvent refers to a single component solvent or a mixture of two or more liquids.
Without intent to limit the scope of the invention, examples and their related results according to the embodiments of the invention are given below. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the invention. Moreover, certain theories are proposed and disclosed herein; however, in no way they, whether they are right or wrong, should limit the scope of the invention so long as the invention is practiced according to the invention without regard for any particular theory or scheme of action.
EXAMPLE 1: FIBERS CONTAINING PERFLUOROSULFONIC ACID IONOMER AND
POLYETHYLENE OXIDE (PEO)
A 25 wt.% solution of Nafion®-PEO (95-5 weight ratio) in Methanol -Water (60-40 wt.%) was loaded into a two-needle centrifugal spinner with a central chamber (see FIG. 1). The needle gauge was either 24G or 26G. Fibers were generated at a rotation speed of about 10,000 rpm. The solution flow rate was about 360 ml/h. The needle to collector distance was typically between 20 and 30 cm, but shorter distance could be used. A comparison of Scanning Electron Microscope (SEM) images of fibers made by electrospinning and fibers made by centrifugal spinning are shown in FIG. 2. The electrospun fibers were made using a single needle spinneret, where the solution flow rate was 0.25 ml/h. This example is intended to demonstrate that centrifugal spinning can be used to prepare charged ionomer fibers with a morphology similar to that of fibers made by electrospinning, where the PEO is used as a carrier polymer and the perfluorosulfonic acid ionomer is in the form of an alcohol/water dispersion.
FIG. 1 shows scanning electron microscope (SEM) images of Nafion®/PEO fibers made by either electrospinning or centrifugal spinning. As can be seen, well-formed fibers are made by centrifugal spinning. This is the first example on the use of a centrifugal spinner to fabricate nanofibers of a perfluorosulfonic acid.
EXAMPLE 2:
FIBERS CONTAINING PARTICLES AND POLYMER BINDER
A centrifugal spinner was used to prepare fibers containing Fe-N-C powder, (from Pajarito Powder, LLC), perfluorosulfonic acid ionomer (Nafion® from Chemours, Inc.) and polyethylene oxide (PEO). The use of the spinning solution composition was 52.5 wt.% Catalyst, 37.3 wt.% Nafion®, and 10.2 wt.% PEO, with a total solids content of 11.4 wt.%. The solvent was a mixture of methylene chloride+ methanol+ water (54.5 wt.%+ 41.0 wt.%+ 4.5 wt.%). Spinning was carried out at an elevated temperature of about 30-40 °C, at a spinning change rotation speed of about 10,000 rpm. Scanning electron microscope (SEM) images of the resulting centrifugal spun fibers are shown in FIG. 2.
FIG. 2 shows SEM images of particle + polymer fibers made by centrifugal spinning. The particles are PGM -free catalyst powder (containing Fe-N-C) from Pajarito Powder. This is the first time a nanofiber has been using a mixture of perfluorosulfonic acid ionomer, polyethylene oxide and nanoparticles. The Fe-C-N powder used in this example has been shown to be an effective platinum-group-metal-free catalyst for the oxygen reduction reaction in proton exchange membrane fuel cells. Thus, the resulting fibers in this example could be used to prepare a fiber mat electrode for a fuel cell or some other electrochemical device. The use of Fe-C-N powder in this example is also intended to show how a nanoparticle can be incorporated into an ion-exchange polymer fiber, to be used in the 3D interlocking fiber junction layer of a bipolar membrane.
The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.
While there has been shown several and alternate embodiments of the invention, it is to be understood that certain changes can be made as would be known to one skilled in the art without departing from the underlying scope of the invention as is discussed and set forth above and below including claims and drawings. Furthermore, the embodiments described above and claims set forth below are only intended to illustrate the principles of the invention and are not intended to limit the scope of the invention to the disclosed elements.
Some references, which may include patents, patent applications and various publications, are cited and discussed in the description of this disclosure. The citation and/or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to the disclosure described herein. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.
LIST OF REFERENCES
[1] C. Chen, M. Dirican, X. Zhang, Centrifugal Spinning — High Rate Production of Nanofibers, in Electrospinning: Nanofabrication and Applications, in Micro and Nano Technologies, Bin Ding, Xianfeng Wang and Jianyong Yu (Eds.), Elsevier, 2019.
[2] X. Zhang and Y. Lu, Centrifugal Spinning: An Alternative Approach to Fabricate Nanofibers at High Speed and Low Cost, Polymer Reviews, 54, 677-701 (2014). [3] B. E. Kwak, H. J. Yoo, E. Lee, and D. H. Kim, Large-Scale Centrifugal Multispinning
Production of Polymer Micro- and Nanofibers for Mask Filter Application with a Potential of Cospinning Mixed Multicomponent Fibers, ACS Macro Lett., 10, 382-388 (2021).
[4] Y. Lu, Y. Li, S. Zhang, G. Xu, K. Fu, H. Lee, X. Zhang, Parameter study and characterization for polyacrylonitrile nanofibers fabricated via centrifugal spinning process, European Polymer Journal, 49, 3834-3845 (2013).

Claims

CLAIMS What is claimed is:
1. A method of fabricating a membrane, comprising: dispersing preformed polymer nanofibers in at least one first solvent to form a dispersion; spraying or coating the dispersion on a surface of a substrate to form a nanofiber-based structure thereon; and evaporating the at least one first solvent from the nanofiber-based structure to form the membrane therewith, wherein the membrane has porosity.
2. The method of claim 1, further comprising, prior to said spraying or coating step, adding nanoparticles to the dispersion.
3. The method of claim 1 or 2, wherein the membrane is a porous nanofiber mat.
4. The method of claim 3, wherein the preformed polymer nanofibers comprise one or more types of preformed charged anion-exchange or cation-exchange polymer nanofibers; the method further comprising: impregnating an uncharged polymer solution containing one or more types of uncharged polymers dispersed in at least one second solvent into the porous nanofiber mat; and evaporating the at least one second solvent from the impregnated porous nanofiber mat, thereby forming a nanofiber-based anion-exchange or cationexchange membrane.
5. The method of claim 3, wherein the preformed polymer nanofibers comprise one or more types of preformed uncharged polymer nanofibers; the method further comprising: impregnating a cation-exchange polymer or anion-exchange polymer solution containing one or more types of cation-exchange polymers or anion-exchange polymers dispersed in at least one third solvent into the porous nanofiber mat; and evaporating the at least one third solvent from the impregnated porous nanofiber mat, thereby forming a nanofiber-based anion-exchange or cationexchange membrane.
6. The method of claim 3, wherein the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion- exchange film; the method further comprising: hot pressing a preformed dense homogeneous or nanofiber-reinforce cationexchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cationexchange films.
7. The method of claim 3, wherein the preformed polymer nanofibers comprise one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cationexchange film; the method further comprising: hot pressing a preformed dense homogeneous or nanofiber-reinforce anion- exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cationexchange films.
8. The method of claim 3, wherein the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers and one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion-exchange film; the method further comprising: hot pressing a preformed dense homogeneous or nanofiber-reinforce cationexchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cationexchange films.
9. The method of claim 3, wherein the preformed polymer nanofibers comprise one or more types of preformed anion-exchange polymer nanofibers and one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; the method further comprising: hot pressing a preformed dense homogeneous or nanofiber-reinforce anion- exchange film onto the nanofiber mat, thereby forming a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cationexchange films.
10. The method of any one of claims 1-9, wherein the charged and/or uncharged polymer nanofibers comprise hydrocarbon polymers.
11. The method of claim 10, wherein the uncharged polymer nanofibers comprise polysulfone, polyethersulfone, polyamide imide, poly(vinylidene fluoride) and/or polyphenylene oxide.
12. The method of claim 10, wherein the charged polymer nanofibers comprise cationexchange and/or anion-exchange polymers.
13. The method of claim 12, wherein the cation-exchange polymer have sulfonate or carboxylate cation-exchange groups.
14. The method of claim 13, wherein the charged polymer nanofibers comprise sulfonated poly(ether ether ketone), sulfonated polysulfone, sulfonated polyphenylene oxide, sulfonated poly(ether sulfone), or sulfonated (polyarylene ether sulfone) cation-exchange sites.
15. The method of claim 12, wherein the anion-exchange polymer has benzyltrialkylammonium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium, quaternary ammonium, or benzyldimethylhexylammonium anion-exchange groups.
16. The method of any one of claims 1-9, wherein the charged and/or uncharged polymer nanofibers comprise fluoropolymers.
17. The method of claim 16, wherein the cation-exchange polymer nanofibers comprise a fluoropolymer with sulfonic acid ion-exchange sites.
18. The method of any one of claims 1-9, wherein said one or more types of preformed charged and/or uncharged polymer nanofibers are crosslinked.
19. The method of any one of claims 1-9, wherein said one or more types of preformed charged and/or uncharged polymer nanofibers contain nanoparticles.
20. The method of claim 19, wherein the nanoparticles are one or more of TiCh, AI2O3, A1(OH)3, nanodiamond, nanographene oxide, and Zr(OH)4.
21. The method of claim 1, wherein the preformed polymer nanofibers are preformed before preparation of the dispersion by a method that does not employ an electric field.
22. The method of claim 21, wherein the preformed polymer nanofibers are made using a centrifugal spinning method or gas jet spinning method.
23. The method of claim 21, wherein the preformed polymer nanofibers comprise two or more different types of polymer nanofibers that are fabricated simultaneously during the spinning process.
24. The method of claim 21, wherein the preformed polymer nanofibers are fabricated with a spinning solution containing a charged or uncharged polymer and a carrier polymer.
25. The method of claim 23, where the carrier polymer comprises poly(ethylene oxide), polyvinyl pyrrolidone, or poly(acrylic acid).
26. A cation-exchange or anion-exchange membrane made by the method of claim 4 or 5.
27. A bipolar membrane made by the method of any one of claims 6-9.
28. An electrochemical device, comprising: one or more membranes made by the method of any one of claims 1-25.
29. An electrodialysis cell, comprising: monopolar cation and anion-exchange membranes and/or bipolar membranes made by the method of any one of claims 1-25.
30. A membrane, comprising: a network of preformed polymer nanofibers, wherein the preformed polymer nanofibers comprise one or more types of preformed uncharged polymer nanofibers, one or more types of preformed charged polymer nanofibers, or a combination of them.
31. The membrane of claim 30, wherein the preformed polymer nanofibers comprise nanoparticles.
32. The membrane of claim 30 or 31, wherein the network of preformed polymer nanofibers is formed by spraying or coating a dispersion comprising the preformed polymer nanofibers in at least one first solvent on a surface of a substrate, followed by solvent evaporation.
33. The membrane of claim 32, wherein the preformed polymer nanofibers comprise said one or more types of preformed charged polymer nanofibers; the membrane further comprising: an unchanged polymer impregnated into the network of preformed polymer nanofibers, whereby the membrane is a nanofiber-based anion-exchange or cationexchange membrane.
34. The membrane of claim 32, wherein the preformed polymer nanofibers comprise said one or more types of preformed uncharged polymer nanofibers; the membrane further comprising: a cation-exchange polymer or anion-exchange polymer impregnated into the network of preformed polymer nanofibers, whereby the membrane is a nanofiber-based anion-exchange or cationexchange membrane.
35. The membrane of claim 32, wherein the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion- exchange film; the membrane further comprising: a preformed dense homogeneous or nanofiber-reinforce cation-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
36. The membrane of claim 32, wherein the preformed polymer nanofibers comprise said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cation-exchange film; the membrane further comprising: a preformed dense homogeneous or nanofiber-reinforce anion-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
37. The membrane of claim 32, wherein the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers and said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce anion- exchange film; the membrane further comprising: a preformed dense homogeneous or nanofiber-reinforce cation-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
38. The membrane of claim 32, wherein the preformed polymer nanofibers comprise said one or more types of preformed anion-exchange polymer nanofibers and said one or more types of preformed cation-exchange polymer nanofibers, and wherein the substrate comprises a preformed dense homogeneous or nanofiber-reinforce cationexchange film; the membrane further comprising: a preformed dense homogeneous or nanofiber-reinforce anion-exchange film hot pressed onto the network of preformed polymer nanofibers, whereby the membrane is a bipolar membrane with a 3D junction layer of interpenetrating and interlocking preformed nanofibers, wherein the junction layer is sandwiched between the anion-exchange polymer and cation-exchange films.
39. The membrane of any one of claims 30-38, wherein the charged and/or uncharged polymer nanofibers comprise hydrocarbon polymers.
40. The membrane of claim 39, wherein the uncharged polymer nanofibers comprise polysulfone, polyethersulfone, polyamide imide, poly(vinylidene fluoride) and/or polyphenylene oxide.
41 . The membrane of claim 39, wherein the charged polymer nanofibers comprise cation-exchange and/or anion-exchange polymers.
42. The membrane of claim 41, wherein the cation-exchange polymers have sulfonate or carboxylate cation-exchange groups.
43. The membrane of claim 42, wherein the charged polymer nanofibers comprise sulfonated poly(ether ether ketone), sulfonated polysulfone, sulfonated polyphenylene oxide, sulfonated poly(ether sulfone), or sulfonated (polyarylene ether sulfone) cation-exchange sites.
44. The membrane of claim 41, wherein the anion-exchange polymers have benzyltrialkylammonium, imidazolium, cyclic ammonium, benzimidazolium, phosphonium, or piperidinium, quaternary ammonium, or benzyldimethylhexylammonium anion-exchange groups.
45. The membrane of any one of claims 30-38, wherein the charged and/or uncharged polymer nanofibers comprise fluoropolymers.
46. The membrane of claim 45, wherein the cation-exchange polymer nanofibers comprise a fluoropolymer with sulfonic acid ion-exchange sites.
47. The membrane of any one of claims 30-38, wherein said one or more types of preformed charged and/or uncharged polymer nanofibers are crosslinked.
48. The membrane of any one of claims 30-38, wherein said one or more types of preformed charged and/or uncharged polymer nanofibers contain nanoparticles.
49. The membrane of claim 48, wherein the nanoparticles are one or more of TiCh, AI2O3, Al(0H)3, nanodiamond, nanographene oxide, and Zr(OH)4.
50. The membrane of claim 32, wherein the preformed polymer nanofibers are preformed before preparation of the dispersion by a method that does not employ an electric field.
51. The membrane of claim 50, wherein the preformed polymer nanofibers are made using a centrifugal spinning method or gas jet spinning method.
52. The membrane of claim 50, wherein the preformed polymer nanofibers comprise two or more different types of polymer nanofibers that are fabricated simultaneously during the spinning process.
53. The membrane of claim 50, wherein the preformed polymer nanofibers are fabricated with a spinning solution containing a charged or uncharged polymer and a carrier polymer.
54. The membrane of claim 53, where the carrier polymer comprises poly(ethylene oxide), polyvinyl pyrrolidone, or poly(aciylic acid).
55. A porous, semi-porous, or dense membrane composed of multiple layers of two or more different polymers, where the layers are made by the sequential deposition of different dispersion of preformed polymer or polymer/particle fibers, or polymer fibers with solid or polymer particles and where the final multilayer film is produced by a hot-pressing step or by some other means of removing some or all of the interfiber void space.
56. An electrochemical device, comprising: one or more membranes of any one of claims 30-55.
EP24846317.6A 2023-07-21 2024-07-22 Fiber materials, fabrication methods and applications of same Pending EP4747437A1 (en)

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