Dale W. Schaefer, Jian ZhaoDepartment of Materials Science and Engineering
University of CincinnatiCincinnati, OH 45221-0012
Janis Brown, Dave Anderson, Max Alexander, Liz Donaldson, Lindsay Richardson and Jeff Baur
Air Force Research LaboratoryDayton, Ohio
Jan Ilavsky National Institutes of Standards and Technology
UNICATAdvanced Photon Source
Argonne National Laboratory, 9700 South Cass AvenueArgonne, IL 60439
Hierarchical Structure of Carbon Nanotubes and Nanofibers
Multi-walled Nanofibers Single-walled Nanotubes
300 nm
1.2 µ
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).
MWNF SWNT
Scattering from Nanotubes
3000 Å
10-2
10-1
100
101
102
103
104
105
106
107
108
109
Cro
ss S
ecti
on (
cm-1
)
10-5 10-4 10-3 10-2 10-1
q (Å)-1
28µ
0.22µ = 220nm
72nm = 720Å
-4
-2.1
-2.2
-4
RLSWNT_PSSO3_Comb RUnifFt99 RLSWNT_PSSO3_pwd_Comb
CLSWNT/PSSO3Level 1 Level 2 Level 3
G 549.02 16876 3.24e+09Rg 721.5 2196.5 2.79e+05B 0.00050344 1.0878e-08 0.00804Pow 2.0999 4.0051 2.216
PSSO3 Dry Powder (USAXS)
PSSO3 Susspension (LS + USAX)
Short-Scale Structure (dried suspension)
0.001
0.01
0.1
1
10
100
Inte
nsi
ty
0.012 3 4 5 6 7 8 9
0.12
q(Å-1)
-4
18 Å =1.8 nm
-2.0
r043_CLSWNT_H2O_PWD_avg_N_B r053_CLSWNT_PAAHCl_DRY_avg_N_B r054_ARSWNT_H2O_pwd_avg_N_B
Power Law Slope= -2.76
ARSWNT_H2O_pwd Level 1 Level 2
G 3.8573 0Rg 18.114 0B 0.0040198 0.021294Pow 2.1332 1.9831
Hard Particle Diameter = 2.4 x RG = 4.3 nm= 43 ÅToo small?
As Received (dirty)
ASI Nanofibers
0.1
1
10
Inte
nsit
y
3 4 5 6 7 8
10-52 3 4 5 6 7 8
10-42 3 4 5 6
q(Å-1)
-1
rASI_21_PSSO3 rASI_21_PMMA rASI_21_PAAHCL
10-3
10-2
10-1
100
101
102
103
104
105
106
107
108
x-r
ay
Cro
ss S
ecti
on
(cm
-1)
10-5 10-4 10-3 10-2 10-1
q(Å-1)
-1.06
-2.80
-3.27
210 Å
4570 Å
Jian PULS Soln USAX Soln
1.2 µ
Light
Light +USAXS+SAXS
Surface roughness?
Large-Scale Structure of Suspended SWNTs and MWNFs
0.1
1
10
Inte
nsi
ty3 4 5 6 7 89
10-5
2 3 4 5 6 7 89
10-4
2 3 4 5 6
q(Å-1)
ASI Nanofibers
-1.0
PSSO3 PMAA PAAHCL
0.01
0.1
1
10
100
1000
Inte
nsi
ty
10-6
2 3 4 5 6 7
10-5
2 3 4 5 6 7
10-4
2 3 4 5 6
q(Å-1)
Clean SWNT
PMAA PSS03 PAAHCL
-1.87
-2.54
-2.22
Comparison of Small-angle Light scattering from nanotubes and nanofibers.Dispersing agents of PMAA, PSSO3 and PAAHCl were used to assist dispersion in water.
SWNT Fractal Structure MWNF Rod-like Structure
SWNT Aggregates are Very Robust
0.1
1
10
100
1000
Inte
nsi
ty
2 4 6 8
10-5
2 4 6 8
10-4
2 4 6
q(Å-1)
Cl SWNT
PSSO3 5 m PSS03 30 s PSSO3 0 s
0.1
1
10
100
1000
Inte
nsi
ty
10-6
2 4 6 8
10-5
2 4 6 8
10-4
2 4 6
q(Å-1)
Cl SWNT
PMAA_5 m PMAA_30 s PMAA_0 s
Reciprocal space data on SWNTs dispersed in water with polystyrene sulfonate and polymethylacrylic acid.. The data is from a Micromeritics Digisizer.
Sonication has little effect on Large Scale Structure of SWNTs
Stress-Strain Data SWNT/PU
0.5
0.4
0.3
0.2
0.1
0.0
Load
(Lb
s)
1.00.80.60.40.20.0Displacement (in/in)
'19.3 %' '24.2%' '10.7 %' '3.8%' '0 %'
Dynamic Mechanical PropertiesStrain Softening
2
3
4
5
6
789
100S
tora
geM
od
ulu
s_M
Pa
0.12 4
12 4
102
Strain_pct
D162_Heather1_17_r1 D163_Heather1_17_r2 D164_Heather1_17_r3
Loading Dependence (MWNTs in PU)
400
300
200
100
0
Sto
rag
eM
od
ulu
s (
MP
a)
0.12 4 6
12 4 6
102
Strain (%)
D187_22_1 D162_17C_1 D181_11C_1 D184_2C_1 D178_0C_1
21.9 %
16.7%
10.7%
1.9%
0 %
0.4
0.3
0.2
0.1
0.0
Tan
Delt
a
0.12 4 6
12 4 6
102
Strain (%)
D187_22_1 D162_17C_1 D181_11C_1 D184_2C_1 D178_0C_1
Modulus Loss
Align De network
Dispersion Strategies: Polyelectrolyte coatings
---- -
Generic Colloid
++
++
+
Nanofiber -Polyelectrolyte Dispersion in PU
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.
50
40
30
20
10
00.01 0.1 1 10
1.0
0.8
0.6
0.4
0.2
0.0
1 Layer 15%
1 2 3 1 2 3
50
40
30
20
10
00.01 0.1 1 10
1.0
0.8
0.6
0.4
0.2
0.0
Uncoated 15% 1 2 3 1 2 3
50
40
30
20
10
00.01 0.1 1 10
1.0
0.8
0.6
0.4
0.2
0.0
2 Layer 15%C
1 2 31 2 3