1 Macroscopic assemblies of aligned nanotubes studied by X-ray diffraction and microdiffraction Laboratoire de Physique des Solides (UMR CNRS 8502), bât. 510, Université Paris Sud, 91405 Orsay cédex, France [email protected]http://www.lps.upsud.fr/Utilisateurs/launois/ Pascale Launois
27
Embed
Macroscopic assemblies of aligned nanotubes studied … · Macroscopic assemblies of aligned nanotubes studied by X-ray diffraction and microdiffraction ... Conclusion. 4 1. Introduction
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Macroscopic assemblies of aligned nanotubes
studied by X-ray diffraction and microdiffraction
Laboratoire de Physique des Solides (UMR CNRS 8502), bât. 510, Université Paris Sud, 91405 Orsay cédex, France
P1Carbon progress (using 13C detection with nuclear microprobe)
I3
13
XRD analysis: the catalyst particles
MWNT (∆)Silicon substrate (+) Particles (o) : isostructural iron oxide phases maghemite or magnetite, γ-Fe2O3 or Fe3O4
(311)
substrate10 μm
2 min
1 μm
M. Pinault, M. Mayne-L’Hermite, C. Reynaud, V. Pichot, P. Launois and D. BallutaudCarbon 43, 2968 (2005)
14
beam position (μm)
(311
) int
ensi
ty (a
.u.)
Si I1 I2
Si substrate
I1
I2
V. Pichot, P. Launois, M. Pinault, M. Mayne-L’Hermite, C. Reynaud, M. Burghammer and C. Riekel,AIP proceedings vol 786, H.Kuzmany et al. Eds., p. 158 (2005)
Microdiffraction: NT alignment V. Pichot, P. Launois, M. Pinault, M. Mayne-L’Hermite, C. Reynaud, M. Burghammer and C. Riekel,AIP proceedings vol 786, H.Kuzmany et al. Eds., p. 158 (2005)
-180 -90 0 90 180
inte
nsity
(a.u
.)
τ (°)
HWHM
when stopping synthesis: the argon gas flushes the remaining aerosol to the reactor
aerosol injection is suddenly stopped
Crucial role of the synthesis procedure
on NT alignment
0 50 100 150
10
20
30
HW
HM
(°)
beam position (µm)
Si substrate
0 50 100 150
10
20
30
HW
HM
(°)
beam position (µm)
17
In brief…
→ Base-growth mechanism
→ Nature and structure of catalyst particles: iron oxyde maghemite or magnetite γ-Fe2O3 or Fe3O4
→ NT alignment / synthesis procedure
Interest of microdiffraction
18
3. SWNT fibers
Aqueous dispersion of SWNTwith sodium dodecyl sulfate (SDS)
is injected in a rotating solution of polyvinyl alcohol (PVA)
Condensation of NT+PVA in a ribbon
Rinsed ribbon suspended in air
FiberSWNT/PVA 50/50 wt %
PVA
Ribbon
NT+SDS
Fiber processing
B. Vigolo, A. Pénicaud, C. Coulon, C. Sauder, R. Pailler, C. Journet, P. Bernier and P. PoulinScience 290, 1331 (2000)P. Poulin, B. Vigolo, A. Pénicaud and C. Coulon, CNRS Patent 0002272 (2000)
CRPPBordeauxFrance
PVA = [ -CH2CHOH- ]n
19
Aim: to modify NT orientation in a fiberto analyze physical properties as a function of orientation
Post-synthesis treatment
ll0
Solvent
m
The fibers are rewetted in a solvent for PVA and are dried under tensile load
B. Vigolo, P. Poulin, M. Lucas, P. Launois, P. Bernier, Appl. Phys. Lett. 81, 1210 (2002)P. Poulin, B. Vigolo, P. Launois, P. Bernier, CNRS patent 0110611 (2001)
0
0
lll −
Draw ratio =
20
Structural analysis by X-ray diffraction
P. Launois, A. Marucci, B. Vigolo, P. Bernier, A. Derré and P. Poulin, J. Nanosci. Nanotechnol. 1, 125 (2001)V. Pichot, S. Badaire, P.-A. Albouy, C. Zakri, P. Poulin and P. Launois, submitted
X-rays2D detector
k0 k 2θB
Fiber
Q
Radial scan ⇒ composition of the fiber
SWNTbundles
amorphousPVA
Azimuthal scans fl orientation
HiPCO SWNT/ PVA fiberτ
21
V. Pichot, S. Badaire, P.-A. Albouy, C. Zakri, P. Poulin and P. Launois, submitted
• Distribution of orientations p(θ) z
•
0 20 40 60
15
20
25
w (°)
draw ratio (%)
from experiments from calculations
0 20 40 60
1
2
3
4
f
draw ratio (%)
from experiments from calculations
fl Two-phase model, oriented and non-oriented fractionsp(θ) = (p1(θ)+f p2)/(1+f), p1: Gaussian function (HWHM w), p2=1/(4π)
Calculations:affine model
of induced orientations at constant volume
NT orientation improved for increasing draw ratios
z’ ≡ NT long axis θ
ϕx
y
z
22
Mechanical propertiesare improved
for better nanotubes alignment
Mechanical properties
V. Pichot, S. Badaire, P.-A. Albouy, C. Zakri, P. Poulin and P. Launois, submitted
E=22GPa
σR=170MPa
23
Continuum mechanics Role of PVA neglected
T. Liu and S. Kumar, Nanoletters 3, 647 (2003)
)(cos2111)(cos22115,0
4
1
12
1221
2
21
12
122θθ ⎟
⎠⎞
⎜⎝⎛ +−++⎟
⎠⎞
⎜⎝⎛ −−+
=
Ev
GEEEEv
GE
E
E1, E2, G12 and v12 = longitudinal modulus, transverse modulus, in-plane shear modulus and Poisson’s ratio of a nanotubes bundle
For perfect alignment, Young modulus → E1/2=320 GPa >> 20 GPa measured
Agreement correct…
but not very good:
role of PVA-NT interactions?
24
Rubber
Draw ratio 300%
From P.A. Albouy, LPS, Orsay France
Cis-polyisopropene
Stearic acid
G.R. Michell , Polymer 25, 1562 (1984)
‘I(τ) may be considered to be the consequence ofsmearing or convoluting the scattering which wouldbe associated with a single orienting structure Iu(τ),
with the orientation function D(τ)’
The observed anisotropy in the scatteringmay be much smaller than
the anisotropy in the molecular orientation
τ
V. Pichot, S. Badaire, P.-A. Albouy, C. Zakri, P. Poulin
and P. Launois, submitted
HiPCO SWNT/ PVA fibers
AmorphousPVA
NT
PVA chains alignment is templated by that of NTs
Same Gaussian fit
Evidence for PVA-NT interactions
25
AmorphousPVA
NT
PVA partial
crystallisationFrom V. Pichot
PhD thesis, Université Paris XI
France (2005)
P. Miaudet, S. Badaire, M. Maugey, A. Derré, V. Pichot, P. Launois, P. Poulin and C. Zakri,Nano Letters 5, 2212 (2005)
Solvent drawing Hot drawing
Improved mechanical properties for improved alignment and PVA crystallization
E=22GPa
σR=170MPa
55J/g> kevlar
E~30GPa
σR~1600MPa
See also:Cadek et al, Nano Lett. 4, 353 (2004)Coleman et al,Adv. Func. Mat. 14, 791 (2004)
Role of the PVA structure
26
In brief…
→ Mechanical properties are improved for improved NT alignment
→ PVA alignment is templated by NTs
→ Mechanical properties depend on PVA-NT interactions