U.S. patent application number 14/773013 was filed with the patent office on 2017-06-01 for graphene entrainment in a host.
The applicant listed for this patent is GARMOR, INC.. Invention is credited to Jeff Bullington, Richard Stoltz.
Application Number | 20170152147 14/773013 |
Document ID | / |
Family ID | 51492002 |
Filed Date | 2017-06-01 |
United States Patent
Application |
20170152147 |
Kind Code |
A9 |
Stoltz; Richard ; et
al. |
June 1, 2017 |
Graphene Entrainment in a Host
Abstract
This is generally a method of producing graphene-containing
suspensions of flakes of high quality graphene/graphite oxides and
method of producing graphene/graphite oxides. Both the exfoliating
graphite into flakes and oxidizing the graphite flakes and the
preparation and suspension of the flakes can be done with high
volume production and at a low cost.
Inventors: |
Stoltz; Richard; (Plano,
TX) ; Bullington; Jeff; (Orlando, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GARMOR, INC. |
Orlando |
FL |
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20160016803 A1 |
January 21, 2016 |
|
|
Family ID: |
51492002 |
Appl. No.: |
14/773013 |
Filed: |
March 7, 2014 |
PCT Filed: |
March 7, 2014 |
PCT NO: |
PCT/US2014/021765 PCKC 00 |
371 Date: |
September 4, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61775024 |
Mar 8, 2013 |
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61775071 |
Mar 8, 2013 |
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61775087 |
Mar 8, 2013 |
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61775099 |
Mar 8, 2013 |
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61775113 |
Mar 8, 2013 |
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61788247 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01B 32/182 20170801;
H01B 1/04 20130101; C01B 32/23 20170801; C01B 32/19 20170801; C01B
32/194 20170801; C01P 2004/24 20130101 |
International
Class: |
C01B 31/04 20060101
C01B031/04; H01B 1/04 20060101 H01B001/04 |
Claims
1. A method of making a graphene suspension, comprising: preparing
graphene flakes with a surface area to thickness ratio greater than
300 Angstroms, and thickness of less than 160 Angstroms, wherein
the graphene flakes have no significant physical surface
distortions and have a surface polarity; preparing a polar or
nonpolar fluid having the same polarity as said graphene flakes;
and suspending said graphene flakes in said fluid by mixing until
the suspension is substantially uniform.
2. The method of claim 1, wherein the suspension is a carbon
allotrope.
3. The method of claim 1, wherein 95% of the flakes are from about
0.8 to 16 nanometers in thickness.
4. The method of claim 1, wherein 95% of the flakes have a surface
area to thickness ratio of a minimum of 300 Angstroms.
5. The method of claim 1, wherein the maximum dimension of the
flakes between 220 Angstroms and 100 microns.
6. The method of claim 1, wherein the Graphene flake has only edge
oxidation.
7. The method of claim 1, wherein a bonding host is added and the
flake surfaces have the same polarity as the bonding host.
8. The method of claim 1, wherein the mechanically exfoliating
graphite into graphene flakes in done in a stirred media mill, and
the stirred media mill is an Attrition mill or a ball mill.
9. The method of claim 1 wherein the method outputs are
substantially limited to substantially flat graphene flakes and
water.
10. A method of making a graphene suspension, comprising: preparing
graphene flakes with a surface area to thickness ratio greater than
300 Angstroms, and thickness of less than 160 Angstroms, wherein
the graphene flakes are substantially planar and have a surface
polarity; and suspending said graphene flakes in a fluid by mixing
until the suspension is substantially uniform.
11. The method of claim 10, wherein 95% of the flakes are from
about 0.8 to 16 nanometers in thickness.
12. The method of claim 10, wherein 95% of the flakes have a
surface area to thickness ratio of a minimum of 300 Angstroms.
13. The method of claim 10, wherein the maximum dimension of the
flakes between 220 Angstroms and 100 microns.
14. The method of claim 10, wherein the method outputs are
substantially limited to substantially flat graphene flakes and
water.
15. A graphene suspension made by a method comprising: preparing
graphene flakes with a surface area to thickness ratio greater than
300 Angstroms, and thickness of less than 160 Angstroms, wherein
the graphene flakes have no significant physical surface
distortions and have a surface polarity; preparing a polar or
nonpolar fluid having the same polarity as said graphene flakes;
and suspending said graphene flakes in said fluid by mixing until
the suspension is substantially uniform.
16. The method of claim 15, wherein 95% of the flakes are from
about 0.8 to 16 nanometers in thickness.
17. The method of claim 15, wherein 95% of the flakes have a
surface area to thickness ratio of a minimum of 300 Angstroms.
18. The method of claim 15, wherein the maximum dimension of the
flakes between 220 Angstroms and 100 microns.
19. A graphene suspension made by a method comprising: preparing
graphene flakes with a surface area to thickness ratio greater than
300 Angstroms, and thickness of less than 160 Angstroms, wherein
the graphene flakes are substantially planar and have a surface
polarity; and suspending said graphene flakes in a fluid by mixing
until the suspension is substantially uniform.
20. The method of claim 19, wherein 95% of the flakes are from
about 0.8 to 16 nanometers in thickness.
21. The method of claim 19, wherein 95% of the flakes have a
surface area to thickness ratio of a minimum of 300 Angstroms.
22. The method of claim 19, wherein the maximum dimension of the
flakes between 220 Angstroms and 100 microns.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates in general to the field of
graphene, and more particularly, to transitioning graphene into a
variety of macroscale mechanical structures.
BACKGROUND OF THE INVENTION
[0002] Without limiting the scope of the invention, its background
is described in connection with composite materials.
[0003] U.S. Pat. No. 8,216,541, issued to Jang, et al. is directed
to a process for producing dispersible and conductive nano-graphene
platelets from non-oxidized graphitic materials. Briefly, these
inventors are said to teach a process for producing nano-graphene
platelets (NGPs) that are both dispersible and electrically
conducting. The process is said to include: (a) preparing a
pristine NGP material from a graphitic material; and (b) subjecting
the pristine NGP material to an oxidation treatment to obtain the
dispersible NGP material, wherein the NGP material has an oxygen
content no greater than 25% by weight. The conductive NGPs are said
to find applications in transparent electrodes for solar cells or
flat panel displays, additives for battery and supercapacitor
electrodes, conductive nanocomposite for electromagnetic wave
interference (EMI) shielding and static charge dissipation.
[0004] United States Patent Publication No. 20120298620, filed by
Jiang, et al., is directed to a method for making graphene
composite structure. Briefly the method is said to include
providing a metal substrate including a first surface and a second
surface opposite to the first surface, growing a graphene film on
the first surface of the metal substrate by a CVD method, providing
a polymer layer on the graphene film and combining the polymer
layer with the graphene film, and forming a plurality of stripped
electrodes by etching the metal substrate from the second
surface.
[0005] Finally, United States Patent Publication No. 20120228555,
filed by Cheng, et al., is directed to a method of making graphene.
Briefly, the application is said to disclose a method for making
graphene by providing a starting material and heating the starting
material for a time and to a temperature effective to produce
graphene. In certain embodiments the applicants are said to use
starting materials that include carbonaceous materials used in
conjunction with, or comprising, sulfur, and essentially free of a
transition metal. The graphene produced by the current method is
said to be used to coat graphene-coatable materials.
SUMMARY OF THE INVENTION
[0006] In one embodiment the present invention includes a method of
making a graphene suspension, comprising: preparing graphene flakes
with a surface area to thickness ratio greater than 300 Angstroms,
and thickness of less than 160 Angstroms, wherein the graphene
flakes have no significant physical surface distortions and have a
surface polarity; preparing a polar or nonpolar fluid having the
same polarity as said graphene flakes; and suspending said graphene
flakes in said fluid by mixing until the suspension is
substantially uniform. In one aspect, the suspension is a carbon
allotrope. In another aspect, 95% of the flakes are from about 0.8
to 16 nanometers in thickness. In another aspect, 95% of the flakes
have a surface area to thickness ratio of a minimum of 300
Angstroms. In another aspect, the maximum dimension of the flakes
between 220 Angstroms and 100 microns. In another aspect, the
Graphene flake has only edge oxidation. In another aspect, the
method further comprises adding a bonding host and the flake
surfaces have the same polarity as the bonding host. In another
aspect, the mechanically exfoliating graphite into graphene flakes
in done in a stirred media mill, and the stirred media mill is an
Attrition mill or ball mill. In another aspect, the method outputs
are substantially limited to substantially flat graphene flakes and
water.
[0007] Another embodiment the present invention includes a method
of making a graphene suspension, comprising: preparing graphene
flakes with a surface area to thickness ratio greater than 300
Angstroms, and thickness of less than 160 Angstroms, wherein the
graphene flakes are substantially planar and have a surface
polarity; and suspending said graphene flakes in a fluid by mixing
until the suspension is substantially uniform. In one aspect, the
suspension is a carbon allotrope. In another aspect, 95% of the
flakes are from about 0.8 to 16 nanometers in thickness. In another
aspect, 95% of the flakes have a surface area to thickness ratio of
a minimum of 300 Angstroms. In another aspect, the maximum
dimension of the flakes between 220 Angstroms and 100 microns. In
another aspect, the Graphene flake has only edge oxidation. In
another aspect, the method further comprises adding a bonding host
and the flake surfaces have the same polarity as the bonding host.
In another aspect, the mechanically exfoliating graphite into
graphene flakes in done in a stirred media mill, and the stirred
media mill is an Attrition mill or ball mill. In another aspect,
the method outputs are substantially limited to substantially flat
graphene flakes and water.
[0008] Yet another embodiment of the present invention includes a
graphene suspension made by a method comprising: preparing graphene
flakes with a surface area to thickness ratio greater than 300
Angstroms, and thickness of less than 160 Angstroms, wherein the
graphene flakes have no significant physical surface distortions
and have a surface polarity; preparing a polar or nonpolar fluid
having the same polarity as said graphene flakes; and suspending
said graphene flakes in said fluid by mixing until the suspension
is substantially uniform. In one aspect, 95% of the flakes are from
about 0.8 to 16 nanometers in thickness. In another aspect, 95% of
the flakes have a surface area to thickness ratio of a minimum of
300 Angstroms. In another aspect, the maximum dimension of the
flakes between 220 Angstroms and 100 microns.
[0009] Yet another embodiment of the present invention includes a
graphene suspension made by a method comprising: preparing graphene
flakes with a surface area to thickness ratio greater than 300
Angstroms, and thickness of less than 160 Angstroms, wherein the
graphene flakes are substantially planar and have a surface
polarity; and suspending said graphene flakes in a fluid by mixing
until the suspension is substantially uniform. In one aspect, 95%
of the flakes are from about 0.8 to 16 nanometers in thickness. In
another aspect, 95% of the flakes have a surface area to thickness
ratio of a minimum of 300 Angstroms. In another aspect, the maximum
dimension of the flakes between 220 Angstroms and 100 microns.
DETAILED DESCRIPTION OF THE INVENTION
[0010] While the making and using of various embodiments of the
present invention are discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts that can be embodied in a wide variety of
specific contexts. The specific embodiments discussed herein are
merely illustrative of specific ways to make and use the invention
and do not delimit the scope of the invention.
[0011] To facilitate the understanding of this invention, a number
of terms are defined below. Terms defined herein have meanings as
commonly understood by a person of ordinary skill in the areas
relevant to the present invention. Terms such as "a", "an" and
"the" are not intended to refer to only a singular entity, but
include the general class of which a specific example may be used
for illustration. The terminology herein is used to describe
specific embodiments of the invention, but their usage does not
delimit the invention, except as outlined in the claims.
[0012] Despite these nanoscale mechanical properties, graphene
previously had not been able to be transitioned to a macro-scale
mechanical structure. The process of producing a loaded host did
not translate to a viable composite structure. The inability to
translate the technology to a viable composite structure was a
combination of technical issues and cost factors, including uniform
distribution of the suspension in the host material. The technical
limitation included stochastic processes in the curing of the host
while obtaining a distribution of the suspension. Curing of the
host material resulted in random shrinkage phenomena, which was
exacerbated in larger composite structures/devices. If a suspension
was added to the host prior to curing, polymerization,
hydrolyzation or other thermal, mechanical, chemical processes that
initiation either long-range or short-range ordering bonding the
distribution of the non-uniform suspension creating weak regions
and failure points in the loaded host material.
[0013] Graphene is an allotrope of carbon. Graphene's purest form
is a one-atom-thick planar sheet of sp.sup.2-bonded carbon atoms
that are densely packed in a honeycomb or hexagonal crystal
lattice. Graphene used as an additive have been shown superior
mechanical, chemical, thermal, gas barrier, electrical, flame
retardant and other properties compared to the native host.
Improvement in the physicochemical properties of the host depends
on: 1) a uniform distribution and entrainment of the graphene
flake, 2) optimizing the interfacial bonding between the graphene
flake and host's matrix, 3) removal of gasses entrained in the host
during processing, 4) optimizing the additive's innate properties,
e.g. flatness, and/or 5) optimizing the thickness to surface-area
ratio of the graphene flake.
[0014] Optimal properties of the graphene flake: We have found that
the performance of a graphene flake is dominated by both the
texture and the surface and edge oxidation/functionalization. A
Hummer's based process produces graphene flakes that have both a
surface and edge oxidation. The degree of oxidation and exfoliation
inherent in the Hummer's or modified based Hummer's process results
in permanent corrugated disfiguration of the graphene flake. The
combination low yield, high cost and inconsistent performance makes
the approach not viable. The permanent corrugated structure
degrades the chemical, mechanical, electrical and thermal
properties of graphene flake. Hence a surface oxidized graphene
flake has lower performance than the single-layer graphene
originally demonstrated when the graphene was first discovered in
2007. This can explain by simple theoretical analysis where the
corrugated structure induces different shearing and loading forces
to the surrounding host as the corrugated structure gives a third
dimension to the ideal two dimension graphene structure. In the
transmission of phonons or electrons the ideal structure is a
uniform flat large area graphene structure. This is illustrated by
the development activities of the semiconductor industry as they
focused chemical vapor deposition thin film generated graphene
material. A corrugated structure induces resistance and inductance
to the transmission of phonons and electrons hence a planar flake
has higher performance in the electron and phonon transmission
relative to a corrugated structure in the surface oxidized graphene
flake.
[0015] This can be a method of making a graphene suspension,
comprising: preparing graphene flakes with a surface area to
thickness ratio greater than 300 Angstroms, and thickness of less
than 160 Angstroms, wherein the graphene flakes have no significant
physical surface distortions and have a surface polarity; preparing
a polar or nonpolar fluid having the same polarity as said graphene
flakes; suspending said graphene flakes in said fluid by mixing
until the suspension is substantially uniform.
[0016] In one embodiment, the suspension is a carbon allotrope; 95%
of the flakes are from about 0.1 to 16 nanometers in thickness; 95%
of the flakes have a surface area to thickness ratio of a minimum
of 300 Angstroms; the maximum dimension of the flakes between 220
Angstroms and 100 microns; the Graphene flake has only edge
oxidation; the flake surface has the same polarity as the bonding
host; the mechanically exfoliating graphite into graphene flakes in
done in a stirred media mill, and the stirred media mill is an
Attrition mill or ball mill; and/or the method outputs are
substantially limited to substantially flat graphene flakes and
water.
[0017] The present invention also includes a method of making a
graphene suspension, comprising: Preparing graphene flakes with a
surface area to thickness ratio greater than 300 Angstroms, and
thickness of less than 160 Angstroms, wherein the graphene flakes
are substantially planar and have a surface polarity; Suspending
said graphene flakes in said fluid by mixing until the suspension
is substantially uniform.
[0018] Recent publications have shown one possible rout to produce
a non corrugated graphene through the of ball milling crystalline
graphite with dry ice the chemo-mechanical processing of the
crystalline graphite produces edge oxidized graphene flakes. This
process shows the feasibility of an edge-only oxidized graphene
flake but cost of this processing is more expensive as required by
a commodity additive market. Note that planar graphene graphite for
research has also been produced by manually separating one layer at
time from a piece of crystalline graphite. Needless to say this is
far too slow and too expensive for commercial production. The
Hummer's based process produces graphene that is not planar,
generally weaken the graphite in a host.
[0019] Optimizing the interfacial bonding between the graphene
flake and host's matrix. Optimizing the interfacial bonding
requires the two critical aspects, first is the providing of a
planar pristine surface that is not distorted through the graphene
production process. Secondly is the modification of the chemistry
of the additive to allow full entrainment of the additive in host's
matrix. For graphene this can be the modifying the OOH group with
other chemical functionality to tailor the additive to be
hydrophilic or hydrophobic and/or create a functional group on the
additive that is similar to the host's chemistry (i.e., polarity,
hydrophilicity, etc.). Creating the correct hydrophobicity allows
the graphene additive to be maintained in suspension in a variety
of common solvent hosts prior to long or short range ordering or
bonding (e.g. a solid). Functionalizing the graphene additive with
a similar chemistry to the host allows the graphene additive to be
directly incorporated in the long or short range ordering or
bonding. The fluids can include plastics, metals, ceramics and
glass.
[0020] Thickness to surface area ratio of the graphene flake: Using
a planar graphene flake the next issue of implementing in a host is
the thickness to surface-area of the graphene flake. The thickness
to surface-area ratio of the graphene flake plays a significant
ability in the graphene flakes ability to positively impact the
host's properties.
[0021] This large surface with a modest thickness is conceptually
comparable to the ideal larger area monolayer need by the
semiconductor industry. A large flat flake will conduct better
phonons and electrons better than the host alone. A multi-layer
graphene flake held bonded even by with van der Waal forces is more
desirable than a thin flake surround by an insulating host. This is
true for mechanical applications as well. As long as there is a
larger surface area to thickness ratio the graphene can mitigate
and distribute a mechanical load giving the host enhanced
mechanical properties, increased tensile, shear, and flexural
strength. The ability to achieve substantial enhancement of the
host's mechanical properties can e.g. be obtained with a flake with
an area of 48,400 .ANG..sup.2 with a flake thickness to 160 .ANG.
to 200 Angstroms. A 48,400 .ANG..sup.2 area flake with a thickness
of 160 .ANG. has a surface area to thickness ratio of about 300
Angstroms can also provide enhancement to the host's mechanical
properties (preferably 95% of the graphene flakes of the present
invention have a surface area to thickness ratio of a minimum of
300 Angstroms).
[0022] In some embodiments our flake thicknesses are 16 nanometers
or less as too many layers significantly reduce the tensile
strength (preferably 95% of the graphene flakes of the present
invention are from about 0.8 to 16 nanometers), and our surface
area to thickness ratio is greater than 48400 to 1 Angstroms.
Preferably, the maximum dimension of the flake varies between 220
Angstroms and 100 microns. This requires precise process control or
a process that allows separation of the graphene flakes by surface
area and/or thickness.
[0023] Uniform distribution and entrainment: The third aspect of
obtaining an effective uniform distribution and entrainment of
graphene flake as an additive in the host fluid is the aggressively
mixing the flake into the host fluid (for example, under an at
least partial vacuum), prior to reacting, casting or otherwise
causing the host to become ordered by thermal, chemical, electrical
or other processes that induce order or bonding in the host, e.g.
solidified of gelled. In some embodiments, epoxy that is dried is
used, and then thermally set after mixing. In one embodiment of the
present invention, greater than 6% loading of graphene is used
(e.g. between 6 and 35%). Studies on attaining increased potency of
fillers by using different mixing techniques, modification of
polymer backbone or filler surface, use of functional polymers and
coupling agents, etc. Graphene, has low surface energy as compared
with crystalline graphite (the cost-effective precursor for
graphene/graphene oxide). One of the routes to overcome this
limitation is the functionalization of flake surface, which results
in significant enhancement of the mechanical and electrical
properties of polymer composites. As graphene is being entrained in
a host a mild vacuum may be applied to prevent gasses from being
incorporated in the host. The formation of gas bubbles increase
resistance to phonon and electron transpiration in addition
creating light scattering centers and mechanical defect sights in a
host.
[0024] Obtaining consistent size and thickness can require
controlled pre-processing (e.g., milling and separation) of the
crystalline graphite. Chemo-mechanical processing can use
crystalline graphite with a mild oxidizing agent in conjunction
with mechanical energy (milling) for synthesis of graphene.
[0025] The mechanical energy in conjunction with a mild oxidizing
environment can produce edge oxidation of the graphene minimizing
the surface oxidation and mechanical defects generated in a
Hummer's based process.
[0026] Graphite (TC306, 30 g) can be used as the starting material
for the graphene chemo-mechanical process. Chemo-mechanical process
can be done in what is generically referred to as a "stirred ball
mill." A useful and simple equation describing the grinding
momentum is M x V (mass x velocity), which enables us to see how an
ball milling use up to 6 lbs (2.7 Kg) (or 2,600 stainless steel
balls) of 0.25'' diameter stainless steel balls weighing 1 g each.
Milling in a closed chamber for 360 minutes at 2,000 RPM or less.
When grinding in the ball milling as the balls (media) in their
random movement are spinning in different rotation and, therefore,
exerting shearing forces on the crystalline graphite. The resulting
graphene preferably has edge-only oxidized flakes with a pristine
surface free of distortions or corrugations with low surface
energies allowing for easier incorporation and entrainment in a
host with enhance graphene physical properties.
[0027] The oxidation of the graphene can occur from a wide range of
methods of making graphene oxide, comprising: Putting crystalline
graphite and an atomizer or aerosolized oxidizing agent in a mill,
wherein the atomizer or aerosolized oxidizing exfoliating agent
contains only carbon, oxygen, hydrogen and combinations thereof;
Milling said crystalline graphite and atomizer or aerosolized
oxidizing exfoliating agent to produce planar graphene flakes
having a thickness of less than 160 Angstroms; and Suspending said
graphene flakes in a fluid to remove the graphene flakes from the
mill.
[0028] This can be a technique for low cost, mass-production of a
partially oxidized to fully oxidized graphite/graphene using
mechanical processing (Attritor Mill) in conjunction with a water
soluble exfoliating agent, such as kaolin clay powder and at least
one of atomizer or aerosolized carbolic acid or oxalic acid
(C.sub.2H.sub.2O.sub.4), acetic acid, carbonic acid or ethanoic
(CH.sub.3CO).sub.2O, and citric acid. Aerosolization can be
accomplished by an Ultrasonic Atomizer Processor, ultrasonic spray
& atomization system made by U&STAR Ultrasonic Technology.
An ultrasonic spray system, uses an ultrasound technology to
atomize liquid or powders generated from ultrasonic energy that
scattered the liquid forming droplets ranging microns to more than
100 microns. Liquid droplets that may contain powders and soluble
matter, promoting chemical reaction, and spraying. This ultrasonic
spray atomization has low power, large volume. An ultrasonic spray
system widely applied on kinds of industrial applications including
ultrasonic spraying liquid, metal power water nebulization or
atomization. The controlled small droplet sizes provide a high
surface to volume ratio enhancing efficiency and control chemical
reactions.
[0029] The atomizer or aerosolized oxidizing agent is injected into
a mill in addition to the crystalline graphite. Directly milling of
graphite powder without concentrated acid, for aerosolized
oxidizing, to produce high quality oxidized graphene. After milling
the crystalline graphite with an aerosolized oxidizing agent is
injected into the attritor mill for a minimum of 30 min to produce
an aqueous slurry. The aqueous slurry contains a mild acid that
breaks down into water and graphite. The water can dissolve the
water-soluble exfoliating agent. An example of a water-soluble
exfoliating agent is kaolin clay powder. The mild aerosolized
oxidizing agent produces oxidized graphene with no distortion or
texturing. Textured graphene oxide produces significant problems
when depositing the graphene oxide, using the graphene oxide in a
suspension or as an additive to other materials.
[0030] Directly milling of graphite powder with a chemically stable
gaseous oxidizing agent in addition to the gaseous oxidizing agent
a water-soluble exfoliating agent, such as kaolin clay powder can
be added to process to produce high quality edge oxidized graphene.
After exfoliating the crystalline graphite in the Attritor mill for
90 min with steel balls and chemically stable gaseous oxidizing
agent is introduced. Once the carbon dioxide is released and the
pressure in the Attritor exceeds two atmospheres the
chemo-mechanical processing initiate graphene oxidation resulting
edge oxidized graphene. As the chemo-mechanical processing
continues pressure in the chamber decreases in the Attritor mill.
Keeping the Attritor mill at an elevate pressure during the
oxidation process enables a higher level of oxidation of the
graphene flakes.
[0031] Additionally graphene oxide may be made, by: Putting
crystalline graphite, and vapor phase oxidizing agent in a mill,
wherein the oxidizing agent comprises nitrogen, carbon, oxygen,
hydrogen and/or combinations thereof; Milling said crystalline
graphite and vapor phase oxidizing agent to produce planar graphene
flakes having a thickness of less than 160 Angstroms; and
Suspending said graphene flakes in a fluid to remove the graphene
flakes from the mill.
[0032] This can also be a method of making graphene oxide,
comprising: Putting crystalline graphite, mineral-based exfoliating
media and vapor phase oxidizing agent in a mill, wherein the
oxidizing agent comprises nitrogen, carbon, oxygen, hydrogen and/or
combinations thereof; Milling said crystalline graphite,
mineral-based exfoliating media and vapor phase oxidizing agent
where water vapor or liquid is combined to produce a mild acidic
slurry where the slurry enhances the exfoliation of the graphite to
produce planar graphene flakes having a thickness of less than 160
Angstroms; and additional water is added at the end of the process
to remove the water soluble exfoliating agent leaving water and
graphene flakes.
[0033] This can be a method of making graphene oxide, comprising:
Putting crystalline graphite and anhydrous oxidizing exfoliating
agent in a mill, wherein the anhydrous oxidizing exfoliating agent
contains only carbon, oxygen, hydrogen and combinations thereof;
Milling said crystalline graphite and anhydrous oxidizing
exfoliating agent to produce planar graphene flakes having a
thickness of less than 160 Angstroms; and Suspending said graphene
flakes in a fluid to remove the graphene flakes from the mill.
[0034] Preferably, the milling is done in a stirred mill; the
stirred mill is an Attrition mill or Attritor; the method outputs
are substantially limited to substantially flat graphene flakes and
carbon, oxygen, hydrogen and combinations thereof; and/or the
anhydrous oxidizing exfoliating agent is at least one of crystal
carbolic acid or anhydrous oxalic acid (C.sub.2H.sub.2O.sub.4),
Acetic anhydride, or ethanoic anhydride (CH.sub.3CO).sub.2O, and
anhydrous citric acid powder.
[0035] If the suspension application requires a narrow size
distribution the edge oxide graphene can be chemically separated
via acidic precipitation by titrating hydrochloric acid into the
bath the larger (thicker/heavier) material comes out of suspension
first creating a narrow graphene oxide flake distribution. The
particle size can be monitored during this process by Dynamic Light
Scattering measurement tool. Dynamic Light Scattering tools can
resolve particle sizes down to 30 .ANG..
[0036] Preferably, the surface area to thickness ratio should be
greater than about 300 to have a positive impact on the host as a
suspension. The pH of the water containing the oxidized
graphite/graphene can range from 5 to 9 while maintaining the
suspension of the media the pH of the resulting water/graphene
mixture is typically is about 7. A chemo-mechanical can be
controlled to process graphene with oxidization of from 1% to 35%.
Unless otherwise indicated or produced by the Hummer process, the
term "graphene" as used herein means graphene with oxidization of
from 1% to 35%. The functionalization can be COOH on the edge
carbons preserving the graphene structure.
[0037] Oxidized graphite produced by this method is typically
hydrophilic and easily suspended in a neutral aqueous solution. The
oxidized graphite can be kept in suspension until varying the pH of
the solution.
[0038] A ball mill operating with less than or equal to 2,000 RPM
can be generally sufficient to prevent agglomeration of the
graphene adhering to the milling balls or tank.
[0039] The graphene can be combined with the host material in a
mechanical agitation process.
[0040] Graphene is diamagnetic and as such dynamic magnetic fields
can be used to enhance orientation and mixing along in addition
other method such as: melt blending, counter rotating screw,
sonication or other mixing processes of the graphene additive into
the host material prior to inducing ordering or bonding in the
host. The entrainment and uniform dispersement preferably uses a
minimum of 30 minutes of and less than 600 minutes in a ball
mill.
[0041] The resulting graphene entrained host can be the cast,
extruded or otherwise processed into the final product by inducing
long or short range ordering or bonding through chemical, thermal,
electrical, shearing, or mechanical treatments.
[0042] Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the invention as defined by the
appended claims. Moreover, the scope of the present application is
not intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present invention, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed, that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present invention. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps.
[0043] It is contemplated that any embodiment discussed in this
specification can be implemented with respect to any method, kit,
reagent, or composition of the invention, and vice versa.
Furthermore, compositions of the invention can be used to achieve
methods of the invention.
[0044] It will be understood that particular embodiments described
herein are shown by way of illustration and not as limitations of
the invention. The principal features of this invention can be
employed in various embodiments without departing from the scope of
the invention. Those skilled in the art will recognize, or be able
to ascertain using no more than routine experimentation, numerous
equivalents to the specific procedures described herein. Such
equivalents are considered to be within the scope of this invention
and are covered by the claims.
[0045] All publications and patent applications mentioned in the
specification are indicative of the level of skill of those skilled
in the art to which this invention pertains. All publications and
patent applications are herein incorporated by reference to the
same extent as if each individual publication or patent application
was specifically and individually indicated to be incorporated by
reference.
[0046] The use of the word "a" or "an" when used in conjunction
with the term "comprising" in the claims and/or the specification
may mean "one," but it is also consistent with the meaning of "one
or more," "at least one," and "one or more than one." The use of
the term "or" in the claims is used to mean "and/or" unless
explicitly indicated to refer to alternatives only or the
alternatives are mutually exclusive, although the disclosure
supports a definition that refers to only alternatives and
"and/or." Throughout this application, the term "about" is used to
indicate that a value includes the inherent variation of error for
the device, the method being employed to determine the value, or
the variation that exists among the study subjects.
[0047] As used in this specification and claim(s), the words
"comprising" (and any form of comprising, such as "comprise" and
"comprises"), "having" (and any form of having, such as "have" and
"has"), "including" (and any form of including, such as "includes"
and "include") or "containing" (and any form of containing, such as
"contains" and "contain") are inclusive or open-ended and do not
exclude additional, unrecited elements or method steps. In
embodiments of any of the compositions and methods provided herein,
"comprising" may be replaced with "consisting essentially of" or
"consisting of". As used herein, the phrase "consisting essentially
of" requires the specified integer(s) or steps as well as those
that do not materially affect the character or function of the
claimed invention. As used herein, the term "consisting" is used to
indicate the presence of the recited integer (e.g., a feature, an
element, a characteristic, a property, a method/process step or a
limitation) or group of integers (e.g., feature(s), element(s),
characteristic(s), propertie(s), method/process steps or
limitation(s)) only.
[0048] The term "or combinations thereof" as used herein refers to
all permutations and combinations of the listed items preceding the
term. For example, "A, B, C, or combinations thereof" is intended
to include at least one of: A, B, C, AB, AC, BC, or ABC, and if
order is important in a particular context, also BA, CA, CB, CBA,
BCA, ACB, BAC, or CAB. Continuing with this example, expressly
included are combinations that contain repeats of one or more item
or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so
forth. The skilled artisan will understand that typically there is
no limit on the number of items or terms in any combination, unless
otherwise apparent from the context.
[0049] As used herein, words of approximation such as, without
limitation, "about", "substantial" or "substantially" refers to a
condition that when so modified is understood to not necessarily be
absolute or perfect but would be considered close enough to those
of ordinary skill in the art to warrant designating the condition
as being present. The extent to which the description may vary will
depend on how great a change can be instituted and still have one
of ordinary skilled in the art recognize the modified feature as
still having the required characteristics and capabilities of the
unmodified feature. In general, but subject to the preceding
discussion, a numerical value herein that is modified by a word of
approximation such as "about" may vary from the stated value by at
least .+-.1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.
[0050] All of the compositions and/or methods disclosed and claimed
herein can be made and executed without undue experimentation in
light of the present disclosure. While the compositions and methods
of this invention have been described in terms of preferred
embodiments, it will be apparent to those of skill in the art that
variations may be applied to the compositions and/or methods and in
the steps or in the sequence of steps of the method described
herein without departing from the concept, spirit and scope of the
invention. All such similar substitutes and modifications apparent
to those skilled in the art are deemed to be within the spirit,
scope and concept of the invention as defined by the appended
claims.
* * * * *