Post on 03-Nov-2018
M I Shahzad1, M Giorcelli1, N Shahzad1,2, S Guastella1, M Castellino1, P Jagdale1 and A Tagliaferro1
1Department of Applied Science and Technology (DISAT), Polytechnic of Turin, Turin-10129, Italy. 2Center for Space Human Robotics, Italian Institute of Technology (IIT), Turin-10129, Italy.
Corresponding Author: Muhammad Imran Shahzad Carbon Group, Department of Applied Science & Technology, Polytechnic of Turin, Turin-10129, Italy
Email: imran.shahzad@polito.it, URL: www.polito.it/carbongroup
FABRICATION OF PDMS-MWCNTs COMPOSITE FILMS
. Schematic of Steps Involved in the Fabrication of PDMS-MWCNTs Composite Films FESEM Images of MWCNTs from Cheaptubes®
The commercial MWCNTs (diameter~10-30nm and
length~20-30μm) from CHEAPTUBES®, produced by
catalyzed chemical vapor deposition are used in this
work. MWCNTs are highly entangled due to Van der
Waals attractive forces.
FTIR Spectra summarizes the positions of IR
absorption bands of the chemical groups found
in the PDMS-MWCNTs composites. There is a
minor shift in the peak at 930 cm−1 with
increasing concentration of CNTs in PDMS. In
addition the ratio between the two
transmission values at 900 cm−1 and 930 cm−1
decrease with increasing CNT content.
Raman spectroscopy is performed using a
green laser source (λ~532nm). The D-peak and
the G-peak are the characteristic peaks of
CNTs. The intensity of these peaks is increasing
proportionally with the increase in CNTs inside
polymer, proving good dispersion of CNTs and
uniformity of films. The other peaks in Raman
spectra are attributed to the PDMS structure.
RAMAN SPECTROSCOPY FTIR SPECTROSCOPY
Embedding CNTs in the PDMS matrix can open new fields of application for this well established polymer. The morphological study proved reasonably well dispersion
and random orientation of CNTs into the PDMS composite films. The Raman Spectroscopy as well as FTIR analysis demonstrated the bonding between CNTs and
polymer. The optical characteristics established that PDMS-MWCNTs composite films are promising materials to extend performance of optical limiting devices and
this effect depends on the quantity of CNTs.
9-13 October, 2012 Islamabad, Pakistan
UV-VIS SPECTROSCOPY OF PDMS-MWCNTs COMPOSITE FILMS
These results suggest that,
through a tuning of the
specular transmittance, these
films might be of interest in
laser technology as optical
absorbers to tune the laser
beam power density.
Absorption A=100-(Rd+Rs)-(Td+Ts)
Absorption Coefficient α=1/t *log(1-R)/T
Transmittance
Reflectance
Optical Density OD = log (1/T)
Diffusivity D = (Td+Rd)/(1-A)
Absorption Coefficient vs Weight % of CNTs in PDMS
Transmittance vs Weight % of CNTs in PDMS
For the comprehensive study
of optical behavior of these
polymeric films, optical
characteristics are measured
both for direct as well as
diffused light. The important
parameters are shown here. 200 300 400 500 600 700 800
0
10
20
30
40
50
60
70
80
90
100
Specular (Ts) + Diffused (Td) PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
Tra
nsm
itta
nce
T(%
)
Wavelength (nm)
---------- Specular (Ts)
200 300 400 500 600 700 800
3
4
5
6
7
8
9
10
11
12
13
200 300 400 500 600 700 800
3
4
5 PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
To
tal R
efl
ecta
nce R
(%)
Wavelength (nm)
Sp
ecu
lar
Refl
ecta
nce R
S(%
)
Wavelength (nm)
500 1000 1500 2000 2500 3000 3500
Ra
ma
n In
ten
sit
y (
a.u
.)
PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
0
Si-
C A
sym
me
tric
Str
ech
ing (
787
cm
-1)
CH
3 S
ym
me
tric
Ro
ckin
g (
862
cm
-1)
Si-C
H3 S
ym
me
tric
Ro
ckin
g (
687
cm
-1)
Raman Shift (cm-1
)
Si-
C S
ym
me
tric
Str
ech
ing (
708
cm
-1)
Si-
O-S
i S
ym
me
tric
Str
ech
ing (
488
cm
-1)
D P
eak M
WC
NT
s (
136
2cm
-1)
G p
eak M
WC
NT
s (
158
2 c
m-1)
CH
3 A
sym
me
tric
Be
nd
ing (
141
2cm
-1)
CH
3 S
ym
me
tric
Be
nd
ing (
126
2 c
m-1
)
CH
3 A
sym
me
tric
S
tre
ch
ing (
296
5 c
m-1
)
CH
3 S
ym
me
tric
Str
ech
ing (
290
7 c
m-1
)
G' pe
ak M
WC
NT
s (
271
1 c
m-1)
0 2 4 6 8 10
2900 3000600 700 800 900 1000 1100 1200 1300 1400 1500
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.96
0.97
0.98
PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
-CH
3 S
ym
me
tric
Satr
etc
h(2
90
0)c
m-1
-CH
3 A
sym
me
tric
Satr
etc
h(2
96
0)c
m-1
Tra
nsm
itta
nc
e (
a.u
)
Wave Number (cm-1)
Si–
O–
Si S
ym
me
tric
al D
efo
rma
tio
n (
101
0)c
m-1
-CH
3R
ockin
g P
ea
ks (
785
-81
5)c
m-1
Si–
C B
and
s (
83
5-8
55
)cm
-1
(90
0-9
30
)cm
-1
–C
H3 S
ym
me
tric
De
form
atio
n (
12
58
)cm
-1
–C
H3 A
sym
me
tric
De
form
atio
n (1
41
0)c
m-1
Pe
ak
Ra
tio
MWCNTs (wt%)
Ratio of Transmission Peaks
at 900 cm-1and 930 cm-1
200 300 400 500 600 700 800
0
20
40
60
80
100
PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
Ab
so
rpti
on
(%
)
Wavelength (nm)
300 350 400 450 500 550 600 650 700 750
0.0
0.5
1.0
1.5
2.0
PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
Op
tic
al D
en
sit
y (
A.U
)
Wavelength (nm)
0
300 350 400 450 500 550 600 650 700 750
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55 PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
Dif
fusit
ivit
y
Wavelength (nm)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
at 300 nm
at 400 nm
at 500 nm
at 600 nm
at 700 nm
at 800 nm 0.0
---------- Specular
Specular + Diffused
MWCNTs (%)
Ab
so
rpti
on
Co
eff
icie
nt
(cm
-1)
2.0x102
0.5 x102
1.0x102
1.5x102
2.5x102
6 5 4 3 2
PDMS_0.0
PDMS_0.5
PDMS_1.0
PDMS_1.5
PDMS_2.0
PDMS_2.5
PDMS_3.0
Ab
so
rpti
on
Co
eff
icie
nt
(cm
-1)
Energy (eV)
4x102
1x102
2x102
3x102
0
- - - - - Specular
Specular + Diffuse 5x10
2
0 0.5 1 1.5 2 2.5 3
0
20
40
60
80
100
Tra
nsm
itta
nce (
%)
MWCNTs (wt%)
at 300nm
at 400nm
at 500nm
at 600nm
at 700nm
at 800nm
---------- Specular
Specular + Diffused
INTRODUCTION The breakthrough of carbon nanotubes (CNTs) has got remarkable progress in various fields of research and applications due to their peculiar structural, electrical,
mechanical and optical properties. CNTs can be up to millimeters long with diameters in the 1-100 nm range, leading to very high aspect ratios. This combination of these
properties allows better interaction in composite matrices, resulting in improved properties and performance.
The incorporation of CNTs into the polymer can enhance the properties of material by increasing mechanical strength and electrical conductivity. However the formation
of aggregates and low dispersions of CNTs in the polymer matrix are the major cause of poor and inhomogeneous composites. Successful integration of CNTs in polymer
matrices could result in different types of lightweight and strong materials for flexible electronic devices and sensors. So, for the exploitation of the potential of CNTs, the
issues regarding economical and controlled fabrication of well dispersed reinforced composite materials has to be tackled and solved. We report here an efficient and
inexpensive process of incorporating carbon MWCNTs into a PDMS (Polydimethylsiloxane) matrix. Furthermore, we focused on their structural and optical properties.
In order to prepare MWCNTs-PDMS composites, different percentages of CNTs has been added to the PDMS
monomer and dispersed by means of mechanical stirring (1000 rpm for 10 min). After the addition of hardener,
the matrix is mixed again. The final step to achieve a uniform dispersion of MWCNTs is sonication (ultrasonic
frequency 37 KHz for 15 min).The composite films with an average thickness of 70 micrometers and different
weight percentages of MWCNTs (from 0.0% to 3.0%) were prepared on glass by Doctor Blade Technique. After
thermal curing at 70°C for 4 hours, the films were detached from the glass surface.
CONCLUSION
FESEM micrographs of PDMS with different weight percentages of MWCNTs a). 1.0 wt% b). 2.0 wt% c). 3.0 wt% at 100kx magnification
FESEM micrographs of PDMS-MWCNTs (3.0 wt %) at a). 10kx b). 50kx c). 200kx
SURFACE MORPHOLOGY OF PDMS-MWCNTs COMPOSITE FILMS