Hierarchical Structure of Carbon Nanotubes and Nanofibers

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Hierarchical Structure of Carbon Nanotubes and
Nanofibers
Dale W. Schaefer, Jian Zhao Department of
Materials Science and Engineering University of
Cincinnati Cincinnati, OH 45221-0012 Janis
Brown, Dave Anderson, Max Alexander, Liz
Donaldson, Lindsay Richardson and Jeff Baur Air
Force Research Laboratory Dayton, Ohio Jan
Ilavsky National Institutes of Standards and
Technology UNICAT Advanced Photon Source Argonne
National Laboratory, 9700 South Cass
Avenue Argonne, IL 60439
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Multi-walled Nanofibers Single-walled
Nanotubes
MWNF
SWNT
TEM comparing MWNFs (left) and SWNTs (right).
Note the branched polymer character of the SWNTs.
The SWNTs are clustered into ropes that are not
disrupted upon water suspension. Images are from
Air Force Research Laboratory (AFRL).
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Scattering from Nanotubes
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Short-Scale Structure (dried suspension)
Hard Particle Diameter 2.4 x RG 4.3 nm 43
Å Too small?
As Received (dirty)
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ASI Nanofibers
Light
Light USAXSSAXS
Surface roughness?
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Large-Scale Structure of Suspended SWNTs and MWNFs
SWNT Fractal Structure
MWNF Rod-like Structure
Comparison of Small-angle Light scattering from
nanotubes and nanofibers.Dispersing agents of
PMAA, PSSO3 and PAAHCl were used to assist
dispersion in water.
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SWNT Aggregates are Very Robust
Sonication has little effect on Large Scale
Structure of SWNTs
Reciprocal space data on SWNTs dispersed in water
with polystyrene sulfonate and polymethylacrylic
acid.. The data is from a Micromeritics
Digisizer.
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Stress-Strain Data SWNT/PU
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Dynamic Mechanical Properties
Strain Softening
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Loading Dependence (MWNTs in PU)
Align
De network
Loss
Modulus
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Dispersion Strategies Polyelectrolyte coatings
Generic Colloid
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Nanofiber -Polyelectrolyte Dispersion in PU
Nanafibers dispersion
Polyelectrolyte-Modified Particles
Nanoparticle/polyurethane composite film
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Mechanical Properties of Coated Nanofiber/PU
Composites
Comparison of DMA data from uncoated, one layer
and two layers coated 15wt nanotubes PU films.
The loss as Tan delta (lower three curves) is
plotted on the right axis. The legend in the
figure indicates the strain sweep sequence.
These samples were all swept three times.