U.S. patent application number 11/857618 was filed with the patent office on 2008-11-27 for calcination of carbon nanotube compositions.
This patent application is currently assigned to The Government of US, as represented by the Secretary of the Navy. Invention is credited to Teddy M. Keller, Matthew Laskoski, Jeffrey W. Long.
Application Number | 20080292530 11/857618 |
Document ID | / |
Family ID | 40072592 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080292530 |
Kind Code |
A1 |
Keller; Teddy M. ; et
al. |
November 27, 2008 |
CALCINATION OF CARBON NANOTUBE COMPOSITIONS
Abstract
A carbon nanotube composition and method of making the same. The
composition is made by: heating a precursor composition under a
non-oxidizing or reducing atmosphere to form a carbon composition
of carbon nanotubes and amorphous carbon; and calcining the carbon
composition in the presence of oxygen to oxidize and vaporize the
amorphous carbon without oxidizing the carbon nanotubes. The
precursor composition includes a mixture or complex of a transition
metal compound and an organic compound that chars at elevated
temperatures.
Inventors: |
Keller; Teddy M.; (Fairfax
Station, VA) ; Laskoski; Matthew; (Springfield,
VA) ; Long; Jeffrey W.; (Alexandria, VA) |
Correspondence
Address: |
NAVAL RESEARCH LABORATORY;ASSOCIATE COUNSEL (PATENTS)
CODE 1008.2, 4555 OVERLOOK AVENUE, S.W.
WASHINGTON
DC
20375-5320
US
|
Assignee: |
The Government of US, as
represented by the Secretary of the Navy
Washington
DC
|
Family ID: |
40072592 |
Appl. No.: |
11/857618 |
Filed: |
September 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60917347 |
May 11, 2007 |
|
|
|
Current U.S.
Class: |
423/447.2 ;
423/447.6 |
Current CPC
Class: |
C01B 32/162 20170801;
C01B 32/168 20170801; B82Y 30/00 20130101; B82Y 40/00 20130101 |
Class at
Publication: |
423/447.2 ;
423/447.6 |
International
Class: |
D01F 9/12 20060101
D01F009/12 |
Claims
1. A carbon nanotube composition made by: heating a precursor
composition under a non-oxidizing or reducing atmosphere and under
thermal conditions effective to form a carbon composition
comprising carbon nanotubes and amorphous carbon; wherein the
precursor composition comprises a mixture or complex of: a
transition metal compound; and an organic compound that chars at
elevated temperatures; and calcining the carbon composition in the
presence of oxygen under thermal conditions that oxidize and
vaporize the amorphous carbon without oxidizing the carbon
nanotubes.
2. The carbon nanotube composition of claim 1, wherein heating the
precursor composition comprises heating the precursor composition
under nitrogen to a temperature of at least about 500.degree.
C.
3. The carbon nanotube composition of claim 1, wherein calcining
the carbon composition comprises heating the carbon composition
under oxygen to a temperature of from about 400.degree. C. to about
500.degree. C.
4. The carbon nanotube composition of claim 1, wherein the
transition metal compound is an organometallic compound, a
transition metal salt, octacarbonyl dicobalt, nonacarbonyl diron,
biscyclooctadiene nickel, ferrocenylethynyl phenylethynylbenzene,
or a combination thereof.
5. The carbon nanotube composition of claim 1, wherein the organic
compound comprises an aromatic group, an ethynyl group, aromatic
precursor, or a combination thereof.
6. The carbon nanotube composition of claim 1, wherein the organic
compound is an aromatic-containing polymer, polyacrylonitrile, a
phthalonitrile-terminated polymer, a phthalonitrile-terminated
bisphenol A-benzophenone polymer, a cyanate ester-terminated
aromatic polymer, a cyanate ester-terminated bisphenol A-benzene
polymer, an aromatic epoxy, a polyether sulfone, a
polyetheretherketone, a phenolic polymer, an aromatic polyimide, a
polyphenylene sulfide, a polycarbonate, coal pitch, petroleum
pitch, 1,2,4,5-tetrakis(phenylethynyl)benzene, or a combination
thereof.
7. The carbon nanotube composition of claim 1, wherein the
precursor composition comprises a metal-ethynyl complex-containing
compound.
8. The carbon nanotube composition of claim 1, wherein the
precursor composition comprises a transition metal salt and an
aromatic compound or a polymer.
9. The carbon nanotube composition of claim 1, wherein carbon
nanotube composition is a porous, solid material; a film; a fiber;
or a shaped solid component.
10. A reduced carbon nanotube composition made by: heating the
carbon nanotube composition of claim 1 under a non-oxidizing or
reducing atmosphere and under thermal conditions effective to
reduce a metal oxide in the carbon nanotube composition to
metal.
11. The reduced carbon nanotube composition of claim 10, wherein
heating the carbon nanotube composition comprises heating the
carbon nanotube composition under hydrogen to a temperature of from
about 500 to about 800.degree. C.
12. The reduced carbon nanotube composition of claim 10, wherein
heating the carbon nanotube composition comprises heating the
carbon nanotube composition under a vacuum.
13. A method comprising: heating a precursor composition under a
non-oxidizing or reducing atmosphere and under thermal conditions
effective to form a carbon composition comprising carbon nanotubes
and amorphous carbon; wherein the precursor composition comprises a
mixture or complex of: a transition metal compound; and an organic
compound that chars at elevated temperatures; and calcining the
carbon composition in the presence of oxygen under thermal
conditions that oxidize and vaporize the amorphous carbon without
oxidizing the carbon nanotubes.
14. The method of claim 13, wherein heating the precursor
composition comprises heating the precursor composition under
nitrogen to a temperature of at least about 500.degree. C.
15. The method of claim 13, wherein calcining the carbon
composition comprises heating the carbon composition under oxygen
to a temperature of from about 400.degree. C. to about 500.degree.
C.
16. The method of claim 13, wherein the transition metal compound
is an organometallic compound, a transition metal salt,
octacarbonyl dicobalt, nonacarbonyl diron, biscyclooctadiene
nickel, ferrocenylethynyl phenylethynylbenzene, or a combination
thereof.
17. The method of claim 13, wherein the organic compound comprises
an aromatic group, an ethynyl group, aromatic precursor, or a
combination thereof.
18. The method of claim 13, wherein the organic compound is an
aromatic-containing polymer, polyacrylonitrile, a
phthalonitrile-terminated polymer, a phthalonitrile-terminated
bisphenol A-benzophenone polymer, a cyanate ester-terminated
aromatic polymer, a cyanate ester-terminated bisphenol A-benzene
polymer, an aromatic epoxy, a polyether sulfone, a
polyetheretherketone, a phenolic polymer, an aromatic polyimide, a
polyphenylene sulfide, a polycarbonate, coal pitch, petroleum
pitch, 1,2,4,5-tetrakis(phenylethynyl)benzene, or a combination
thereof.
19. The method of claim 13, wherein the precursor composition
comprises a metal-ethynyl complex-containing compound.
20. The method of claim 13, wherein the precursor composition
comprises a transition metal salt and an aromatic compound or a
polymer.
21. The method of claim 13, wherein carbon nanotube composition is
a porous, solid material; a film; a fiber; or a shaped solid
component.
22. The method of claim 13, further comprising heating the product
of calcining the carbon composition under a non-oxidizing or
reducing atmosphere and under thermal conditions effective to
reduce a metal oxide in the product of calcining the carbon
composition to metal.
23. The method of claim 22, wherein heating the product of
calcining the carbon composition comprises heating the product of
calcining the carbon composition under hydrogen to a temperature of
from about 500 to about 800.degree. C.
24. The method of claim 22, wherein heating the carbon nanotube
composition comprises heating the carbon nanotube composition under
a vacuum.
Description
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/917,347, filed on May 11, 2007. This
application and all other referenced publications and patent
documents throughout this application are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The invention is generally related to carbon nanotube
compositions.
DESCRIPTION OF RELATED ART
[0003] Since the discovery of carbon nanotubes, many studies have
been carried out in an effort to increase the production yield, to
reduce the cost, to remove amorphous carbon, and to improve the
quality of carbon nanotubes. Small quantities of carbon nanotubes
can now be produced daily by methods such as arc discharge, laser
vaporization, and chemical vapor decomposition (CVD). These methods
yield carbon nanotubes embedded in powdered soot. The synthesis of
cost-effective, good quality carbon nanotubes in high yields
remains a challenge in these systems. Experimental tests and
applications of such carbon structures have been hampered by the
difficulty in obtaining pure, homogenous, and uniform samples of
highly graphitic nanotubes. The impurities in the soot are
amorphous carbon and high concentrations of metal nanoparticles.
Some of the amorphous carbon can be removed from the soot by
calcination to enhance the purity of the nanotubes. Multiple
washing with acid solutions removes some of the metal impurities
but at least 5-10% by weight of metal remains in all samples. The
washings can also damage the nanotubes. The purer carbon nanotubes
produced by the CVD method are available as a powder but do not,
exhibit structural integrity.
SUMMARY OF THE INVENTION
[0004] Disclosed herein is a carbon nanotube composition and method
of making the same. The composition is made by: heating a precursor
composition under a non-oxidizing or reducing atmosphere and under
thermal conditions effective to form a carbon composition
comprising carbon nanotubes and amorphous carbon; and calcining the
carbon composition in the presence of oxygen under thermal
conditions that oxidize and vaporize the amorphous carbon without
oxidizing the carbon nanotubes. The precursor composition comprises
a mixture or complex of: a transition metal compound; and an
organic compound that chars at elevated temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] A more complete appreciation of the invention will be
readily obtained by reference to the following Description of the
Example Embodiments and the accompanying drawings.
[0006] FIG. 1 shows the synthetic scheme for synthesis of carbon
nanotubes in bulk solid.
[0007] FIG. 2 shows scanning electron micrographs (SEM) of the
surface of a pyrolyzed, Ni-catalyzed multi-walled nanotube (MWNT)
solid (a) before, and (b) after calcination at 480.degree. C.
[0008] FIG. 3 shows X-ray diffraction studies confirming the
removal of amorphous carbon in a calcined CNT sample. The top graph
(as pyrolyzed to 1000.degree. C.) shows intensity due to the
amorphous carbon content between 20 and 25 degrees on the 2-theta
axis.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0009] In the following description, for purposes of explanation
and not limitation, specific details are set forth in order to
provide a thorough understanding of the present invention. However,
it will be apparent to one skilled in the art that the present
invention may be practiced in other embodiments that depart from
these specific details. In other instances, detailed descriptions
of well-known methods and devices are omitted so as to not obscure
the description of the present invention with unnecessary
detail.
[0010] The disclosed method pertains to a general and broad method
for the purification of carbon nanotubes, formed in a solid
carbonaceous solid, using selective combustion techniques under
oxidizing conditions (i.e., calcination). Calcination at selected
temperatures permits the removal of the amorphous carbon from the
carbonaceous solid, while preserving the carbon nanotube content.
During the formation and production of carbon nanotubes by heat
treatment of a precursor composition such as an organometallic
compound or a carbon source and varying amount of a metal salt or
organometallic compound, carbon nanotubes and some amorphous carbon
are formed in the carbonaceous solid. The amount of carbon
nanotubes and amorphous carbon in the carbonaceous solid will
depend on the temperature and the time of exposure. By this method,
the amorphous carbon is removed oxidatively by heating the
carbonaceous solid in a flow of air or O.sub.2 at various
temperatures up to about 500.degree. C. leaving the crystalline
nanotubes intact in the shaped solid. Within the carbonaceous
solid, metal nanoparticles can be present in catalytic or in larger
quantities depending on the amount of reactants used in the
preparation. The metal nanoparticles may be oxidized during the
calcination.
[0011] Any organic compound that chars can be used as a precursor
for the formation of carbon nanotube-metal nanoparticle
compositions in a shaped carbonaceous solid during the
carbonization process. Resins such as polyimides, epoxies,
phthalonitriles, cyanate ester resins, polyacrylonitrile, phenolic
resins, petroleum and coal pitches, polyaromaticetherketone (PEEK),
and polyaromaticsulfones (PES) can be used as the precursor and
converted into a carbon nanotube carbonaceous composition by
exposure to elevated temperatures. Suitable precursor materials are
disclosed in U.S. Pat. Nos. 6,673,953, 6,846,345, and 6,884,861 and
in US Patent Application Publication Nos. 2003-0108477 and
2006-0130609. The precursor materials are either physically mixed
with or coated in solution with metal salts, metallocenes, or other
transition metal compounds that decompose upon thermal treatment
yielding metal atoms, clusters, and/or nanoparticles. Depending on
the precursor material, film, fiber, and shaped solid carbon
nanotube compositions can be easily formulated by the method.
Polyacrylonitrile and the pitches are commercially available and
are currently used in the fabrication of carbon and graphite
fibers, respectively. Phenolic resins are used as the matrix
material in the formulation of carbon-carbon composites. Films,
fibers, and shaped components of the material can be readily
obtained. Carbon nanotube fibers may be made from inexpensive
precursors that are presently being used to spin commercial fibers.
The method may be used as an inexpensive method for the formation
iii situ of carbon nanotubes using existing commercial materials.
This method may permit the development of applications pertaining
to purified carbon nanotubes within a shaped solid. This method may
potentially increase the importance of carbon nanotubes for
microelectronic, electrical, magnetic, battery, fuel cell, solar
cell, electrochemical capacitors, hydrogen storage, catalytic, and
structural applications.
[0012] The synthetic strategy adds to the prior chemical synthesis
of carbon nanotubes in high yield and in bulk carbonaceous solids
from heat treatment of transition metal complexes of aromatic-based
compounds, transition metal salts and aromatic compounds, and
organometallic-containing aromatic compounds above 500.degree. C.
(FIG. 1). Any high performance compound or polymer containing a
high proportion of aromatic units or aromatic precursors that char
or retain weight upon heat treatment at elevated temperatures may
afford carbon nanotubes in the presence of the appropriate
transition metal. A number of the precursor compounds and polymers
are commercially available. Studies have shown that only metal
nanoparticles that are generated in situ and that chemically
interact with the precursor organic materials during the heat
treatment can be used to form carbon nanotubes within the charred
carbonaceous compositions. The metal nanoparticle size and
concentration can be changed by varying the concentration of
precursor material and organometallic compound or metal salt. Some
of the carbonaceous non-magnetic metal nanoparticle compositions
exhibit superconductive properties.
[0013] One goal can be to purify and to eliminate undesirable
materials within the carbonaceous solid yielding a nanostructure
mainly consisting of carbon nanotubes. The metal nanoparticles may
be present in only catalytic amount depending on the metal
concentration in the precursor composition. Micrographic analysis
reveals that the as-prepared bulk carbonaceous solids contain a
high fraction of multi-walled carbon nanotubes (MWNTs), which are
embedded in a relatively dense solid of amorphous carbon (see FIG.
2), with very low surface areas (<10 m.sup.2/g) for the overall
composite. A selective combustion process can be used to achieve
more porous and purified MWNT structures, essentially eliminating
the amorphous carbon phase (see FIG. 2(b)). In essence, the
amorphous carbon component can be used as a porogen (i.e., pore
forming agent) that can be selectively removed in this case by
calcination at 480.degree. C. to yield a highly porous carbon
nanotube solid. The effects of this calcination procedure were
further confirmed by N.sub.2-sorption measurements, which
demonstrated that the calcination of a Ni-catalyzed bulk carbon
solid at .about.430.degree. C. increases the specific surface areas
from 10 m.sup.2/g up to 430 m.sup.2/g, while also introducing
networks of mesopores and small macropores with cumulative pore
volumes of up to 0.80 cm.sup.3/g. X-ray diffraction (FIG. 3)
studies have confirmed that the selective combustion process
removes the amorphous carbon phase while preserving the nanotubes.
Depending on the precursor system and application, fibers, films,
powders, and matrix components can be formulated and purified by
the method.
[0014] Carbon nanotubes synthesized by CVD and other reported
methods occur from the vapor phase yielding impure carbon nanotubes
in soot. As formed, the disclosed carbon nanotube-containing
carbonaceous solids may contain much less metal relative to the CVD
and other methods. The amorphous carbon can be removed from the
soot by a calcination procedure yielding purified carbon nanotubes
as a powdered composition. In contrast to the other methods, large
amounts of carbon nanotubes can be formulated inexpensively by the
presently disclosed method during the carbonization process in a
solid configuration. The metal nanoparticles formed during the
creation of the carbon nanotubes may be oxidized to the metal oxide
during the calcination procedure. A potential advantage of this
approach is that shaped solid components, fibers, and films can be
readily fabricated from the melt or amorphous state of the
precursor compounds. This method permits the removal of the
amorphous carbon from the solid carbon containing the nanotubes,
which enhances the importance of the carbon nanotubes for battery,
fuel cell, membrane, microelectronic, sensor, solar, hydrogen
storage, and structural applications. Depending on the formulation
parameters, the physical properties of the purified carbonaceous
material can be varied for potential magnetic, electrical,
structural, catalytic, and medical applications.
[0015] The shaped product (solid, film, or fiber) remaining after
the calcination process can contain high purity carbon nanotubes
with some metal nanoparticles as oxides, whose concentration can be
easily varied. Since carbon nanotubes and transition metal
nanoparticles are homogeneously dispersed in varying amounts in the
carbonaceous shaped compositions, new technologies based on the
carbon nanotube and carbon nanotube metal oxide nanoparticles can
be readily developed from the materials of this invention.
[0016] A variety of transition metal compounds, transition metal
salts, and organic compounds may be used. Suitable transition metal
compounds include, but are not limited to, organometallic compound,
transition metal salt, octacarbonyl dicobalt, nonacarbonyl diron,
biscyclooctadiene nickel, ferrocenylethynyl phenylethynylbenzene,
and combinations thereof. The organic compound may comprise an
aromatic group, an ethynyl group, aromatic precursor, and
combinations thereof. Aromatic precursors are compounds that can be
converted to aromatic compounds, such as an aromatic polymer,
polyacrylonitrile. Suitable organic compounds include, but are not
limited to, a phthalonitrile-terminated polymer, a
phthalonitrile-terminated bisphenol A-benzophenone polymer, a
cyanate ester-terminated aromatic polymer, a cyanate
ester-terminated bisphenol A-benzene polymer, an aromatic epoxy, a
polyether sulfone, a polyetheretherketone, a phenolic polymer, an
aromatic polyimide, a polyphenylene sulfide, a polycarbonate, coal
pitch, petroleum pitch, 1,2,4,5-tetrakis(phenylethynyl)benzene, and
combinations thereof. The precursor composition may comprise a
metal salt and an aromatic compound or polymer. More than one salt
may be used in combination as long as at least one of the salts is
a transition metal salt. One suitable non-transition metal salt is
an aluminum salt.
[0017] A single compound may serve as both the transition metal
compound and the organic compound, such as a metal-ethynyl
complex-containing compound. Such compounds may be made by, for
example, reacting a metal carbonyl with an ethynyl compound such as
1,2,4,5-tetrakis(phenylethynyl)benzene.
[0018] The carbon composition may be made by heating precursor
composition under a non-oxidizing atmosphere or a reducing
atmosphere and under thermal conditions effective to form the
carbon composition comprising carbon nanotubes and amorphous
carbon. Such conditions are disclosed in U.S. Pat. Nos. 6,673,953,
6,846,345, and 6,884,861 and in US Patent Application Publication
Nos. 2003-0108477 and 2006-0130609 and include, but are not limited
to, at least about 500.degree. C., at least about 1000.degree. C.,
and from about 800 to about 1300.degree. C. under nitrogen. The
presence of carbon nanotubes may be verified by, for example, SEM
and/or X-ray diffraction. The carbon composition is then calcined
to remove the amorphous carbon to leave behind carbon nanotubes.
This may be done, for example, by heating under oxygen to a
temperature of from about 400.degree. C. to about 500.degree. C.
Removal of the amorphous carbon may be verified by, for example,
SEM and/or X-ray diffraction. The resulting carbon nanotube
composition may be a porous, solid material and may be in the form
of a fiber, film, or shaped solid component.
[0019] The carbon nanotube composition may contain nanoparticles of
metal oxide. In may be desirable to reduce these nanoparticles to
metal. This may be done by further processing the carbon nanotube
composition by heating under a non-oxidizing or reducing atmosphere
and under thermal conditions effective to reduce a metal oxide in
the carbon nanotube composition to metal. Suitable conditions
include, but are not limited to, heating under hydrogen to a
temperature of from about 500 to about 800.degree. C.
[0020] Having described the invention, the following examples are
given to illustrate specific applications of the invention. These
specific examples are not intended to limit the scope of the
invention described in this application.
Example 1
[0021] Synthesis of 1:20 molar
octacarbonyldicobalt/polyacrylonitrile mixture--Co.sub.2(CO).sub.8
(50 mg, 0.146 mmol), polyacrylonitrile (1.00 g), and 10 mL of
methylene chloride were added to a 50 mL round bottomed flask. The
polyacrylonitrile did not dissolve. The slurry was allowed to stir
for 5 min before the solvent was removed under reduced pressure.
The mixture was vacuum dried and isolated as an off-white
solid.
Example 2
[0022] Thermal conversion of 1:20 molar
octacarbonyldicobalt/polyacrylonitrile mixture to carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/polyacrylonitrile mixture (22.8 mg) was heated
in a TGA chamber under nitrogen at 10.degree. C./min to
1000.degree. C. resulting in a shaped composition and a char yield
of 36%. The differential thermal analysis (DTA) curve showed an
exotherm at 308.degree. C. X-ray diffraction (XRD) studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbon composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt nanoparticles. The
X-ray (002) reflection for carbon nanotubes is readily
apparent.
Example 3
[0023] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/polyacrylonitrile mixture--The composition
from Example 2 (15 mg) was heated in a TGA chamber at 10.degree.
C./min to 410.degree. C. and isothermed for 4 hours under air. XRD
studies confirmed the presence of carbon nanotubes-cobalt
nanoparticles in the carbon composition. XRD analysis confirmed a
reduction in the amorphous carbon. SEM studies confirmed the
presence of pores in the sample. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt nanoparticles. The
X-ray (002) reflection for carbon nanotubes was readily
apparent.
Example 4
[0024] Synthesis of 1:100 molar
octacarbonyldicobalt/polyacrylonitrile mixture--Co.sub.2(CO).sub.8
(10 mg, 0.0292 mmol), polyacrylonitrile (1.00 g), and 10 mL of
methylene chloride were added to a 50 mL round bottomed flask. The
polyacrylonitrile did not dissolve. The slurry was allowed to stir
for 5 min before the solvent was removed under reduced pressure.
The mixture was vacuum dried and isolated as an off-white
solid.
Example 5
[0025] Thermal conversion of 1:100 molar
octacarbonyldicobalt/polyacrylonitrile mixture to carbon
nanotube-cobalt nanoparticle composition--A 1:100 molar
octacarbonyldicobalt/polyacrylonitrile mixture (25.32 mg) was
heated in a TGA chamber under nitrogen at 10.degree. C./min to
1000.degree. C. resulting in a shaped composition and a char yield
of 35%. The DTA curve showed an exotherm at 295.degree. C. XRD
studies confirmed the presence of carbon nanotubes-cobalt
nanoparticles in the carbon composition. The XRD study showed the
four characteristic reflections [(002), (100), (004), and (110)]
values for carbon nanotubes and the pattern for cobalt
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 6
[0026] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:100 molar
octacarbonyldicobalt/polyacrylonitrile mixture--The composition
from Example 5 (20 mg) was heated in a TGA chamber at 10.degree.
C./min to 410.degree. C. and isothermed for 6 hours under air. XRD
studies confirmed the presence of carbon nanotubes-cobalt
nanoparticles in the carbon composition. XRD analysis confirmed a
reduction in the amorphous carbon. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt nanoparticles. The
X-ray (002) reflection for carbon nanotubes was readily
apparent.
Example 7
[0027] Synthesis of 1:20 molar
1-(ferrocenylethynyl)-3-(phenylethynyl)benzene/polyacrylonitrile
mixture--1-(ferrocenylethynyl)-3-(phenylethynyl)benzene (10 mg,
0.0259 mmol), polyacrylonitrile (500 mg), and 10 mL of methylene
chloride were added to a 50 mL round bottomed flask. The
polyacrylonitrile did not dissolve. The slurry was allowed to stir
for 5 min before the solvent was removed under reduced pressure.
The mixture was vacuum dried and isolated as an orange solid.
Example 8
[0028] Thermal conversion of 1:20 molar
1-(ferrocenylethynyl)-3-(phenylethynyl)benzene/polyacrylonitrile
mixture to carbon nanotube-iron nanoparticle composition--A 1:20
molar
1-(ferrocenylethynyl)-3-(phenylethynyl)-benzene/polyacrylonitrile
mixture (30.26 mg) was heated in a TGA chamber under nitrogen at
10.degree. C./min to 1000.degree. C. resulting in a shaped
composition and a char yield of 33%. The DTA curve showed an
exotherm at 297.degree. C. XRD studies confirmed the presence of
carbon nanotubes-iron nanoparticles in the carbon composition. The
XRD study showed the four characteristic reflections [(002), (100),
(004), and (110)] values for carbon nanotubes and the pattern for
iron nanoparticles. The X-ray (002) reflection for carbon nanotubes
was readily apparent.
Example 9
[0029] Calcination of the carbon nanotube-iron nanoparticle
composition in air prepared from a 1:20 molar
1-(ferrocenylethynyl)-3-(phenylethynyl)benzene/polyacrylonitrile
mixture--The composition from Example 8 (20 mg) was heated in a TGA
chamber at 10.degree. C./min to 425.degree. C. and isothermed for 4
hours under air. XRD studies confirmed the presence of carbon
nanotubes-iron nanoparticles in the carbon composition. XRD
analysis confirmed a reduction in the amorphous carbon. SEM studies
confirmed the presence of pores in the sample. The XRD study showed
the four characteristic reflections [(002), (100), (004), and
(110)] values for carbon nanotubes and the pattern for iron
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 10
[0030] Synthesis of 1:20 molar octacarbonyldicobalt/phthalonitrile
mixture--The phthalonitrile resin (a 2:1 oligomer of bisphenol A
and benzophenone capped with phthalonitrile units) (200 mg, 0.225
mmol) was dissolved in 10 mL of methylene chloride in a 25 mL round
bottomed flask. Co.sub.2(CO).sub.8 (10 mg, 0.0292 mmol) dissolved
in 2 mL of hexanes was added and a brown precipitate formed. The
solvent was removed under reduced pressure, the mixture vacuum
dried, and the product isolated as a dark brown solid.
Example 11
[0031] Thermal conversion of 1:20 molar
octacarbonyldicobalt/phthalonitrile mixture to carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/phthalonitrile mixture (38.01 mg) was heated
in a TGA chamber under nitrogen at 10.degree. C./min to
1000.degree. C. resulting in a shaped composition and a char yield
of 47%. The DTA curve showed exotherms at 163, 276, 514 and
868.degree. C. XRD studies confirmed the presence of carbon
nanotubes-cobalt nanoparticles in the carbon composition. The XRD
study showed the four characteristic reflections [(002), (100),
(004), and (110)] values for carbon nanotubes and the pattern for
cobalt nanoparticles. The X-ray (002) reflection for carbon
nanotubes was readily apparent.
Example 12
[0032] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/phthalonitrile mixture--The composition from
Example 11 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 445.degree. C. and isothermed for 5 hours under air. XRD studies
confirmed the presence of carbon nanotubes-iron nanoparticles in
the carbon composition. XRD analysis confirmed a reduction in the
amorphous carbon. SEM studies confirmed the presence of pores in
the sample. The X-ray diffraction study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for iron nanoparticles. The
X-ray (002) reflection for carbon nanotubes was readily
apparent.
Example 13
[0033] Thermal conversion of 1:20 molar
octacarbonyldicobalt/phthalonitrile/bis[4-(3-aminophenoxy)phenyl]sulfone
mixture to carbon nanotube-cobalt nanoparticle composition--A 1:20
molar
octacarbonyl-dicobalt/phthalonitrile/bis[4-(3-aminophenoxy)phenyl]sulfone
mixture (100 mg) was melted with
bis[4-(3-aminophenoxy)phenyl]sulfone (2 mg) at 180.degree. C. The
mixture was cooled and a sample cured under nitrogen in a TGA
chamber by heating at 250.degree. C. for 1 h, 300.degree. C. for 2
h, 350.degree. C. for 6 h, and 375.degree. C. for 4 h. The shaped
composition was cooled and heated under nitrogen at 10.degree.
C./min to 1000.degree. C. resulting in a char yield of 67%. The DTA
curve showed exotherms at 530 and 751.degree. C. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbon composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt nanoparticles. The
X-ray (002) reflection for carbon nanotubes was readily
apparent.
Example 14
[0034] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/phthalonitrile/bis[4-(3-aminophenoxy)phenyl]sulfone
mixture--The composition from Example 13 (20 mg) was heated in a
TGA chamber at 10.degree. C./min to 425.degree. C. and isothermed
for 10 hours under air. XRD studies confirmed the presence of
carbon nanotubes-cobalt nanoparticles in the carbon composition.
XRD analysis confirmed a reduction in the amorphous carbon. The XRD
study showed the four characteristic reflections [(002), (100),
(004), and (110)] values for carbon nanotubes and the pattern for
cobalt nanoparticles. The X-ray (002) reflection for carbon
nanotubes was readily apparent.
Example 15
[0035] Synthesis of 1:20 molar octacarbonyldicobalt/cyanate ester
mixture--A cyanate ester resin (a 2:1 oligomer of bisphenol A and
1,3-dibromobenzene terminated with cyanate ester units) (1.09 g,
1.88 mmol) was dissolved in 10 mL of methylene chloride in a 25 mL
round bottomed flask. Co.sub.2(CO).sub.8 (55 mg, 0.161 mmol)
dissolved in 2 mL of hexanes was added. The mixture was stirred for
5 min and the solvent was removed under reduced pressure. The
mixture was vacuum dried and the product isolated as a blue
oil.
Example 16
[0036] Thermal conversion of 1:20 molar
octacarbonyldicobalt/cyanate ester mixture to carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/cyanate ester mixture (31.38 mg) was cured
under nitrogen in a TGA chamber by heating at 100.degree. C. for 1
h, 150.degree. C. for 2 h, 200.degree. C. for 2 h, 300.degree. C.
for 2 h, and 350.degree. C. for 1 h. The shaped composition was
cooled and heated at 10.degree. C./min to 1000.degree. C. under
nitrogen resulting in a char yield of 34%. The DTA curve showed
exotherms at 549 and 810.degree. C. The latter peak was assigned to
the formation of carbon nanotubes. XRD studies confirmed the
presence of carbon nanotubes-cobalt nanoparticles in the carbon
composition. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt and cobalt oxide
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 17
[0037] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/cyanate ester mixture--The composition from
Example 16 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 420.degree. C. and isothermed for 8 hours under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbon composition. XRD analysis confirmed a reduction in the
amorphous carbon. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 18
[0038] Synthesis of 1:20 molar octacarbonyldicobalt/epoxy
mixture--The epoxy Novolac resin (supplied by The Dow Chemical
Company) (2.34 g), 1,3-bis(3-aminophenoxy)-benzene (1.17 g, 4.00
mmol), and Co.sub.2(CO).sub.8 (175 mg, 0.513 mmol) were dissolved
in 10 mL of methylene chloride in a 25 mL round bottomed flask. The
mixture was stirred for 5 min and the solvent was removed under
reduced pressure. The mixture was vacuum dried and the product
isolated as a blue oil.
Example 19
[0039] Thermal conversion of 1:20 molar octacarbonyldicobalt/epoxy
mixture to carbon nanotube-cobalt nanoparticle composition--A 1:20
molar octacarbonyldicobalt/epoxy mixture (56.16 mg) was cured under
nitrogen in a TGA chamber by heating at 80.degree. C. for 2 h,
100.degree. C. for 1 h, 150.degree. C. for 1 h, 200.degree. C. for
1 h, and 250.degree. C. for 1 h. The shaped composition was cooled
and heated at 10.degree. C./min to 1000.degree. C. under nitrogen
resulting in a char yield of 23%. The DTA curve showed an exotherm
at 831.degree. C. attributed to the formation of carbon nanotubes.
XRD studies confirmed the presence of carbon nanotubes-cobalt
nanoparticles in the carbonaceous composition. The XRD study showed
the four characteristic reflections [(002), (100), (004), and
(110)] values for carbon nanotubes and the pattern for cobalt and
cobalt oxide nanoparticles. The X-ray (002) reflection for carbon
nanotubes was readily apparent.
Example 20
[0040] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/epoxy mixture--The composition from Example 19
(20 mg) was heated in a TGA chamber at 110.degree. C./min to
420.degree. C. and isothermed for 10 hours under air. X-ray studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbon composition. XRD analysis confirmed a reduction in the
amorphous carbon. SEM studies confirmed the presence of pores in
the sample. The X-ray diffraction study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt nanoparticles. The
X-ray (002) reflection for carbon nanotubes was readily
apparent.
Example 21
[0041] Synthesis of 1:20 molar
octacarbonyldicobalt/polyethersulfone mixture--The polyethersulfone
(200 mg) and Co.sub.2(CO).sub.8 (10 mg, 0.0292 mmol) were dry mixed
and pulverized for 5 min in a Wiggle-Bug.
Example 22
[0042] Thermal conversion of 1:20 molar
octacarbonyldicobalt/polyethersulfone mixture to carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/polyethersulfone mixture (39.49 mg) was heated
in a TGA chamber at 10.degree. C./min to 1000.degree. C. under
nitrogen resulting in a shaped composition and a char yield of 44%.
The DTA curve showed an exotherm at 581.degree. C. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt and cobalt oxide
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 23
[0043] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/polyethersulfone mixture--The composition from
Example 22 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 460.degree. C. and isothermed for 1 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis confirmed a reduction in
the amorphous carbon. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 24
[0044] Synthesis of 1:20 molar
octacarbonyldicobalt/polyetheretherketone (PEEK) mixture--The PEEK
(200 mg) and Co.sub.2(CO).sub.8 (10 mg, 0.0292 mmol) were dry mixed
and pulverized for 5 min in a Wiggle-Bug.
Example 25
[0045] Thermal conversion of 1:20 molar octacarbonyldicobalt/PEEK
mixture to carbon nanotube-cobalt nanoparticle composition--A 1:20
molar octacarbonyldicobalt/PEEK mixture (35.25 mg) was heated in a
TGA chamber at 10.degree. C./min to 1000.degree. C. under nitrogen
resulting in a shaped composition and a char yield of 42%. XRD
studies confirmed the presence of carbon nanotubes-cobalt
nanoparticles in the carbonaceous composition. The X-ray
diffraction study showed the four characteristic reflections
[(002), (100), (004), and (110)] values for carbon nanotubes and
the pattern for cobalt and cobalt oxide nanoparticles. The X-ray
(002) reflection for carbon nanotubes was readily apparent.
Example 26
[0046] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/PEEK mixture--The composition from Example 25
(20 mg) was heated in a TGA chamber at 10.degree. C./min to
450.degree. C. and isothermed for 2 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis confirmed a reduction in
the amorphous carbon. SEM studies confirmed the presence of pores
in the sample. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 27
[0047] Synthesis of 1:20 molar octacarbonyldicobalt/phenolic resin
mixture--The phenolic resin (1.00 g) (a Novolac-type
phenol-formaldehyde polymer), octamethylenetetramine (80 mg, 0.571
mmol) and Co.sub.2(CO).sub.8 (50 mg, 0.146 mmol) were mixed
together in 10 mL of methylene chloride. The mixture was stirred
for 5 min and the solvent was removed under reduced pressure. The
mixture was vacuum dried and the product isolated as brown
solid.
Example 28
[0048] Thermal conversion of a 1:20 molar
octacarbonyldicobalt/phenolic resin mixture to a carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/phenolic resin mixture (23 mg) was cured under
nitrogen in a TGA chamber by heating at 150.degree. C. for 2 h,
200.degree. C. for 2 h, 300.degree. C. for 1 h, and 350.degree. C.
for 1 h. The shaped composition was cooled and heated at 10.degree.
C./min to 1000.degree. C. under nitrogen resulting in a char yield
of 50%. XRD studies confirmed the presence of carbon
nanotubes-cobalt nanoparticles in the carbonaceous composition. The
X-ray diffraction study showed the four characteristic reflections
[(002), (100), (004), and (110)] values for carbon nanotubes and
the pattern for cobalt and cobalt oxide nanoparticles. The X-ray
(002) reflection for carbon nanotubes was readily apparent.
Example 29
[0049] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/phenolic resin mixture--The composition from
Example 28 (20 mg) was heated in a TGA chamber at 10C/min to
450.degree. C. and isothermed for 2 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis confirmed a reduction in
the amorphous carbon. SEM studies confirmed the presence of pores
in the sample. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 30
[0050] Synthesis of 1:20 molar octacarbonyldicobalt/polyimide
mixture--The polyimide monomer (500 mg) (Thermid 600) and
Co.sub.2(CO).sub.8 (25 mg, 0.0730 mmol) were mixed together in 10
mL of methylene chloride. The polyimide did not dissolve. The
mixture was stirred for 5 min and the solvent was removed under
reduced pressure. The mixture was vacuum dried and the product
isolated as a brown solid.
Example 31
[0051] Thermal conversion of a 1:20 molar
octacarbonyldicobalt/polyimide mixture to a carbon nanotube-cobalt
nanoparticle composition--A sample of the mixture polyimide monomer
and Co.sub.2(CO).sub.8 was cured under nitrogen in a TGA chamber by
heating at 315.degree. C. for 3 h. The shaped composition was
cooled and heated at 10.degree. C./min to 1000.degree. C. under
nitrogen resulting in a char yield of 60%. XRD studies confirmed
the presence of carbon nanotubes-cobalt nanoparticles in the
carbonaceous composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt and cobalt oxide
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 32
[0052] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/polyimide mixture--The composition from
Example 31 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 455.degree. C. and isothermed for 4 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis confirmed a reduction in
the amorphous carbon. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 33
[0053] Synthesis of 1:20 molar octacarbonyldicobalt/polyphenylene
sulfide mixture--The powdered poly(1,4-phenylene sulfide) (1.00 g)
and Co.sub.2(CO).sub.8 (50 mg, 0.146 mmol) were mixed together in 5
mL of methylene chloride. The heterogeneous mixture was stirred for
5 min and the solvent was removed under reduced pressure. The
mixture was vacuum dried and the product isolated.
Example 34
[0054] Thermal conversion of a 1:20 molar
octacarbonyldicobalt/polyphenylene sulfide mixture to a carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/polyphenylene sulfide (35 mg) was heated at
10.degree. C./min to 1000.degree. C. tinder nitrogen resulting in a
shaped component with a char yield of 40%. XRD studies confirmed
the presence of carbon nanotubes-cobalt nanoparticles in the
carbonaceous composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt and cobalt oxide
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 35
[0055] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/polyphenylene sulfide--The composition from
Example 34 (20 mg) was heated in a TGA chamber at 10C/min to
455.degree. C. and isothermed for 4 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis confirmed a reduction in
the amorphous carbon. SEM studies confirmed the presence of pores
in the sample. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 36
[0056] Synthesis of 1:20 molar octacarbonyldicobalt/polycarbonate
mixture--The powdered poly(bisphenol A carbonate) (2.00 g) and
Co.sub.2(CO).sub.8 (100 mg, 0.293 mmol) were mixed together in 5 mL
of methylene chloride. The heterogeneous mixture was stirred for 5
min and the solvent was removed under reduced pressure. The mixture
was vacuum dried and the product isolated.
Example 37
[0057] Thermal conversion of a 1:20 molar
octacarbonyldicobalt-/polycarbonate mixture to a carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/polycarbonate mixture (22.48 mg) was heated at
10.degree. C./min to 1000.degree. C. under nitrogen resulting in a
shaped component with a char yield of 35%. XRD studies confirmed
the presence of carbon nanotubes-cobalt nanoparticles in the
carbonaceous composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt and cobalt oxide
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 38
[0058] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt-/polycarbonate mixture--The composition from
Example 37 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 425.degree. C. and isothermed for 14 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis showed a reduction in
the amorphous carbon. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 39
[0059] Synthesis of 1:20 molar octacarbonyldicobalt/coal pitch
mixture--The coal tar pitch (1.18 g) and Co.sub.2(CO).sub.8 (59 mg,
0.172 mmol) were mixed together in 5 mL of methylene chloride. The
mixture was stirred for 5 min and the solvent was removed under
reduced pressure. The mixture was vacuum dried and the product
isolated as a black oil.
Example 40
[0060] Thermal conversion of a 1:20 molar octacarbonyldicobalt/coal
pitch mixture to a carbon nanotube-cobalt nanoparticle
composition--A 1:20 molar octacarbonyldicobalt/coal pitch mixture
(46 mg) was heated at 10.degree. C./min to 1000.degree. C. under
nitrogen resulting in a shaped component with a char yield of 30%.
XRD studies confirmed the presence of carbon nanotubes-cobalt
nanoparticles in the carbonaceous composition. The XRD study showed
the four characteristic reflections [(002), (100), (004), and
(110)] values for carbon nanotubes and the pattern for cobalt and
cobalt oxide nanoparticles. The X-ray (002) reflection for carbon
nanotubes was readily apparent.
Example 41
[0061] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/coal pitch mixture--The composition from
Example 40 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 420.degree. C. and isothermed for 10 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis showed a reduction in
the amorphous carbon. SEM studies confirmed the presence of pores
in the sample. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 42
[0062] Synthesis of 1:20 molar octacarbonyldicobalt/petroleum pitch
mixture--The petroleum pitch (1.05 g) and Co.sub.2(CO).sub.8 (53
mg, 0.154 mmol) were mixed together in 5 mL of methylene chloride.
The mixture was stirred for 5 min and the solvent was removed under
reduced pressure. The mixture was vacuum dried and the product
isolated as a black oil.
Example 43
[0063] Thermal conversion of a 1:20 molar
octacarbonyldicobalt/petroleum pitch mixture to a carbon
nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/petroleum pitch mixture (52 mg) was heated at
10.degree. C./min to 1000.degree. C. under nitrogen resulting in a
shaped component with a char yield of 29%. XRD studies confirmed
the presence of carbon nanotubes-cobalt nanoparticles in the
carbonaceous composition. The XRD study showed the four
characteristic reflections [(002), (100), (004), and (110)] values
for carbon nanotubes and the pattern for cobalt and cobalt oxide
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 44
[0064] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air prepared from a 1:20 molar
octacarbonyldicobalt/petroleum pitch mixture--The composition from
Example 43 (20 mg) was heated in a TGA chamber at 10.degree. C./min
to 440.degree. C. and isothermed for 3 hour under air. XRD studies
confirmed the presence of carbon nanotubes-cobalt nanoparticles in
the carbonaceous composition. XRD analysis showed a reduction in
the amorphous carbon. The XRD study showed the four characteristic
reflections [(002), (100), (004), and (110)] values for carbon
nanotubes and the pattern for cobalt nanoparticles. The X-ray (002)
reflection for carbon nanotubes was readily apparent.
Example 45
[0065] Synthesis of 1:20 hexacarbonyldicobalt complex of
1,2,4,5-tetrakis(phenylethynyl)benzene--Co.sub.2(CO).sub.8 (0.1 g,
0.29 mmol) and 75 mL of dry hexane were added to a 100 mL round
bottomed flask. While stirring, the mixture was cooled to
-78.degree. C., evacuated, and purged with argon three times to
remove air. 1,2,4,5-Tetrakis(phenylethynyl)benzene (2.8 g, 5.8
mmol) dissolved in 100 mL of methylene chloride was added by
syringe resulting in the formation a white precipitate. The mixture
turned yellow, was allowed to warm to room temperature, and was
stirred for 3 hr resulting in dissolution of the solid and a color
change to dark green. The formation of the green solution is
apparently due to the reaction of the Co.sub.2(CO).sub.8 with an
alkyne group of 1,2,4,5-tetrakis(phenylethynyl)benzene. The solvent
was removed at reduced pressure. The product was used as prepared
for characterization studies.
Example 46
[0066] Thermal conversion of 1:20 molar
octacarbonyldicobalt/1,2,4,5-tetrakis(phenylethynyl)benzene mixture
to carbon nanotube-cobalt nanoparticle composition--A 1:20 molar
octacarbonyldicobalt/1,2,4,5-tetrakis(phenylethynyl)benzene mixture
(20 mg) was heated in a TGA chamber under nitrogen at 10.degree.
C./min to 1000.degree. C. resulting in a shaped composition and a
char yield of 80%. XRD studies confirmed the presence of carbon
nanotubes-cobalt nanoparticles in the carbonaceous composition. The
XRD study showed the four characteristic reflections [(002), (100),
(004), and (110)] values for carbon nanotubes and the pattern for
cobalt nanoparticles. The X-ray (002) reflection for carbon
nanotubes was readily apparent.
Example 47
[0067] Calcination of the carbon nanotube-cobalt nanoparticle
composition in air 1:20 molar
octacarbonyldicobalt/1,2,4,5-tetrakis(phenylethynyl)benzene
mixture--The composition from Example 46 (15 mg) was heated in a
TGA chamber at 10.degree. C./min to 420.degree. C. and isothermed
for 30 min under air. XRD studies confirmed the presence of carbon
nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD
analysis showed a reduction in the amorphous carbon. The XRD study
showed the four characteristic reflections [(002), (100), (004),
and (110)] values for carbon nanotubes and the pattern for cobalt
nanoparticles. The X-ray (002) reflection for carbon nanotubes was
readily apparent.
Example 48
[0068] Thermal conversion of 1:20 molar
Ni(COD).sub.2/1,2,4,5-tetrakis(phenylethynyl)benzene mixture to
carbon nanotube-nickel nanoparticle composition--A 1:20 molar bis
(cyclooctadiene) nickel
(Ni(COD).sub.2)/1,2,4,5-tetrakis(phenylethynyl)benzene mixture (35
mg) (prepared from 1.7 g (3.6 mmol, 20 equiv) of
1,2,4,5-tetrakis(phenylethynyl)benzene and 0.05 g, (0.18 mmol, 1
equiv) of Ni(COD).sub.2, by mixing in a solution of 65 mL of hexane
and 65 mL of CH.sub.2Cl.sub.2, and concentrating to dryness) was
heated in a TGA chamber under nitrogen at 10C/min to 1300.degree.
C. resulting in a shaped composition and a char yield of 80%. XRD
studies confirmed the presence of carbon nanotubes-nickel
nanoparticles in the carbonaceous composition. The XRD study showed
the four characteristic reflections [(002), (100), (004), and
(110)] values for carbon nanotubes and the pattern for nickel
nanoparticles. FIG. 1 shows a SEM studies on the surface of the
surface of the bulk sample. The X-ray (002) reflection for carbon
nanotubes was readily apparent.
Example 49
[0069] Calcination of the carbon nanotube-nickel nanoparticle
composition in air prepared from 1:20 molar
Ni(COD).sub.2/1,2,4,5-tetrakis(phenylethynyl)benzene mixture--The
composition from Example 48 (15 mg) was heated in a TGA chamber at
10.degree. C./min to 425.degree. C. and isothermed for 2 hours
under air. XRD studies confirmed the presence of carbon
nanotubes-nickel nanoparticles in the carbonaceous composition. XRD
analysis confirmed a reduction in the amorphous carbon (see FIG.
3). SEM studies confirmed the presence of pores in the sample (see
FIG. 2). The XRD study showed the four characteristic reflections
[(002), (100), (004), and (110)] values for carbon nanotubes and
the pattern for nickel nanoparticles. The X-ray (002) reflection
for carbon nanotubes was readily apparent.
Example 50
[0070] Thermal conversion of 1:20 molar
Fe.sub.2(CO).sub.9/1,2,4,5-tetrakis(phenylethynyl)benzene mixture
to carbon nanotube-nickel nanoparticle composition--A 1:20 molar
Fe.sub.2(CO).sub.9/1,2,4,5-tetrakis(phenylethynyl)benzene mixture
(52 mg) (prepared from 1,2,4,5-tetrakis(phenylethynyl)benzene (0.10
g, 0.21 mmol) and Fe.sub.2(CO).sub.9 (0.0038 g, 0.0104 mmol) by
mixing in a solution of 65 mL of hexane and 65 mL of
CH.sub.2Cl.sub.2, and concentrating to dryness) was heated in a TGA
chamber under nitrogen at 10.degree. C./min to 1000.degree. C.
resulting in a shaped composition and a char yield of 83%. XRD
studies confirmed the presence of carbon nanotubes-iron
nanoparticles in the carbonaceous composition. The X-ray
diffraction study showed the four characteristic reflections
[(002), (100), (004), and (110)] values for carbon nanotubes and
the pattern for iron nanoparticles. The X-ray (002) reflection for
carbon nanotubes was readily apparent.
Example 51
[0071] Calcination of the carbon nanotube-nickel nanoparticle
composition in air prepared from 1:20 molar
Fe.sub.2(CO).sub.9/1,2,4,5-tetrakis(phenylethynyl)benzene
mixture--The composition from Example 50 (15 mg) was heated in a
TGA chamber at 10.degree. C./min to 400.degree. C. and isothermed
for 20 hours min under air. XRD studies confirmed the presence of
carbon nanotubes-nickel nanoparticles in the carbonaceous
composition. XRD analysis confirmed a reduction in the amorphous
carbon. The XRD study showed the four characteristic reflections
[(002), (100), (004), and (110)] values for carbon nanotubes and
the pattern for iron nanoparticles. The X-ray (002) reflection for
carbon nanotubes was readily apparent.
Example 52
[0072] Thermal Processing Of As-Pyrolyzed Carbon Nanotube
Solids--Following the carbonization process, the carbon solid is
heated in either air or O.sub.2 (static or flowing) to temperatures
ranging from 400-520.degree. C., to remove amorphous carbon via
selective combustion, while leaving the carbon nanotube phase
intact. The exact processing conditions for this selective
combustion process are determined by first characterizing the
carbon solid by thermogravimetric analysis and differential
scanning calorimetric under flowing air or O.sub.2. The selective
combustion process also converts the metal catalyst from its
metallic to its oxide form, as shown in the XRD patterns in FIG. 3
for a Ni-catalyzed CNT solid. A subsequent thermal treatment under
reducing conditions (flowing H.sub.2 or vacuum) can be used to
convert the metal oxide phase back to its metallic form.
Example 53
[0073] Reduction Of Metal Oxide Formed During Calcination To
Elemental Metal--Following the selective combustion process to
remove the amorphous content from the bulk carbon nanotube solid,
the material formed in Example 52 can be subjected to an additional
thermal treatment under de-oxygenating conditions, for the purpose
of reducing the oxidized metal catalyst back to its original
metallic form, and also reducing carbon-oxygen functional groups
that form on the nanotube surface during the selective combustion
purification. Typically the carbon nanotube solid would be heated
under dilute or pure hydrogen at temperatures from 500-800.degree.
C. for several hours. Alternatively the carbon nanotube solid could
be heated under vacuum at similar temperatures to de-oxygenate and
reduce metal oxides and oxidized carbon functionalities in the
material.
[0074] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that the claimed invention may be
practiced otherwise than as specifically described. Any reference
to claim elements in the singular, e.g., using the articles "a,"
"an," "the," or "said" is not construed as limiting the element to
the singular.
* * * * *