1. Purification of Single-Walled Carbon Nanotubes and the Production
of Nanotube/Elastin composite
B. Zhao, A. A. Puretzky, D. Styers-Barnett, H. Hu, I. Ivanov, C. M. Rouleau, and D. B. Geohegan
the Center for Nanophase Materials Sciences and Material Science & Technology Division
Oak Ridge National Laboratory, Oak Ridge, TN
Abstract Characterization of as-prepared SWNTs and Purified SWNTs Production of SWNT/Elastin Composite Material
Single-walled carbon nanotubes (SWNTs) have great potentials in many applications SEM and TEM images of Raw SWNTs Elastin
because of their unique structure and properties. We report a scalable purification of - elastic fiber insoluble
SWNTs synthesized by high-power laser vaporization, and the production of SWNT/elastin Synthesized with Different Amount of Catalysts Nitric Acid Effects to SWNTs
composites. Such material would be promise for new generalization of biocomposites.
0.5% Ni-Co
SWNTs were synthesized by high-power (600 W) laser ablation facility of carbon targets Purity Yield Met. Residue Purification 0.7 controlled by pH
with Ni and Co as catalysts at 20 gram scale. The purification carries out at 10 gram per run Condition (%) (%) (wt%) Effect* 0.6
0.58 0.58
stretch relax and temperature
0.5
by using nitric acid refluxing, controlled-pH water-extraction, and hydrogen peroxide 12M/4h 51 52 1.7 0.26
0.4
0.37
0.39 elastin molecule
treatment. The purification efficiency of each step was monitored by SEM, TEM, TGA, and 7M/18h 88 42 2 0.37 0.3 0.26
solution phase NIR spectroscopy. The purified SWNTs contain metal residue less than 1% 3M/48h 74 53 2 0.39 0.2
0.1
and carbonaceous purity among the highest ever reported. 3M/18h 83 70 2.2 0.58
0 soluble
7M/6h 80 73 2.4 0.58 12M /4h 7M /18h 3M /48h 3M /18h 7M /6h
1.0% Ni-Co
Purified SWNTs are used to make nanotube/elastin composites. SWNT/elastin composite cross-link
* Purification Effect = Purity X Yield
is produced at controlled temperature and pH conditions. The electrical and mechanical
properties of SWNT/elastin composite thin film are studied.  Amphiphilic fibrous proteins (contains proline, glycine, lycine, etc.).
 Cross-linked polypeptide chains to form rubberlike, elastic fibers.
 Reversible uncoiling/recoiling forms based on pH and temperature.
Raman Spectroscopy TGA data
Synthesis of Single-Wall Carbon Nanotubes 100 nm
1.5% Ni-Co Method
by Laser Ablation Method 20000
As-prepared SWNTs
D/G = 0.11
100
586
1.0 SWNTs
80
Raman Intensity (a.u.)
60 0.5
Co-Ni/Dylon target 10000 elastin SWNT/elastin
40
solution sonication solution
Weight (%)
20 AP-SWNT residue: 10%
carbon 0.0
0 0 2
nanotube Ultra-purified SWNTs 100
655
deposition 40000
D/G = 0.03 80 SWNT/elastin composite
laser 60 1
40
Ar
20000
20 Purified SWNT 1.2
TEM image of SWNT/elastin thin film
residue: 1%
1000 sccm quartz tube Images of Purified SWNTs 0
500 1000 1500 2000
0
0
SWNT/elastin
Furnace: 1150oC 100 200 300 400 500 600 700 800 900 1000
Absorption Intensity (a.u.)
Pressure: 500 Torr Frequency (cm )
-1
Temperature ( C)
o elastin 20 nm
1.0
 10 gram scale production 0.8
 carbon materials with different forms
carbon 0.6
nanotubes
0.4
1J/500Hz/1ms Solution Phase NIR Spectroscopy
0.2
catalyst 0.0
100J/5Hz/20ms carbon
free nanohorns 1.0
500 1000 1500 2000 SWNT network
raw SWNTs purity: 30% Wavelength (nm) embedded in elastin
acid treated SWNTs 40%
Absorption Intensity (a.u.)
0.8 washed SWNTs 112%
purified SWNTs 214%
ultra-purified SWNTs 232%
0.6
Carbon Nanotube Purification Method Purity Evaluation of SWNTs
0.4
Conclusion
Tools to assess SWNT purity:
Raw SWNTs Purity: 30~50%  SWNTs can be synthesized by high power laser ablation at 20 gram scale.
• remove metal catalyst Metal: 10~15wt%  SEM and TEM – amorphous carbon and defect sites 0.2
 A multi-step purification method, including nitric acid oxidation, thermal annealing, H2O2
• remove amorphous carbon  TGA – metal content
1) HNO3 12M/4h oxidation, and surfactant washing, have applied to purify SWNTs. The highest purity of
• exfoliate SWNT bundle
2) centrifuge/decantation  NIR spectroscopy – interband transition 0.0 purified SWNTs reaches 232% against reference sample.
• introduce functionalities 400 600 800 1000 1200 1400
 Raman spectroscopy – D/G ratio Frequency (cm )
-1  SWNT/elastin composite material is produced at controlled pH and temp. conditions, which
is a potential material in biological application.
Acid treated SWNTs Purity: 80~120% Purity evaluation by solution phase NIR method
Metal: 2~3wt%
Yield: 40~60% 0.1
R X
Future Work
AA(S,R) AA(S,X)
• remove amorphous carbon 30% H2O2 treatment
Absorbance
0.0
0.4  Continue on optimizing purification method of SWNTs.
AA(T,X) Results:  Study the biocompatibility and conductivity of SWNT/elastin composite material.
 Application of SWNT/elastin composite material in artificial skin.
AA(T,R)
Purity: 160~200% 0.2
SWNTs: 67%
Purified SWNTs Metal: 3~5wt%
Yield: 8~10% 0.0
REFERENCE (R)
8000
CARBONACEOUS
IMPURITIES: 33%
10000 12000
• NIR: very high purity 232%!
Acknowledgement
8000 10000 12000
500oC, air, 30min Wavenumber (cm )
-1
• Raman: D/G ratio decreased from 0.11 to 0.03
• remove amorphous carbon wash with 6M HCl AA(S, R)
= 0.141
AA(S, X)
= 0.095 • TGA: metal residue decreased to 1%
• remove metal catalyst dry under vacuum AA(T, R) AA(T, X) This research was conducted in the Functional Nanomaterials Theme at the Center for
• Dispersible by DMF, SDS/H2O, etc. Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the
Purity of X against R = (0.095/0.141)*100% =67%
Purity: 210~230%
M. E. Itkis, et. al. Nano Lett. 2003, 3, 309.
Division of Scientific User Facilities, U.S. Department of Energy.
Metal: ~1wt%
ultra-Purified SWNTs Yield: 4~5%
Collaboration: please visit http://www.cnms.ornl.gov for user project information.