Nanosize Surface Electromodification
of Carbon Fibers by Conductive
Polymers and
Their Characterizations
Prof.Dr.A.Sezai.SARAÇ
Istanbul Technical University
Department of Chemistry &
Polymer Science and Technology
Maslak 80626
Istanbul,Turkey
1
Carbon fiber reinforcement
of polymeric composites
5-7μ



Carbon fibers(CF) are used in composites(i.e.,PAN based
CF) in order to produce materials of lower density and
greater strength. advanced structural materials: aircraft,
spacecraft, and suspension bridges –
The most widely used composite material in tactical
aircraft is a carbon fibre/epoxy
A polymeric ‘interface’ acting as a coupling agent,
improve the interfacial properties between reinforcing
(carbon) fibers and the polymeric matrix .
A.S. Sarac, A. Bismarck, E. Kumru, J. Springer,Synth. Met. 123 (2001) 411-423
E.Kumru,J.Springer,A.S.Sarac,A.Bismarck., Synth. Met. 123(2001)391-402
2
Biosensor Appl.

Electromodified carbon fibers also have potential for biosensor
applications as microelectrodes
-working in small volumes of solutions-


Homogeneous Conductive Polymer coated -surface functionalities is
suitable for the miniaturization of electrode system for a particular
analyte.
Several copolymer and polymer coated electrodes(Cz based) were shown
to be an effective disposable microelectrode system for the determination
of p-aminophenol at low detection limits
M. Jamal, E. Magner, A.S.Sarac, Sensors and Actuators 97 (2004)59-66
3
Carbon Fiber Reinforcement
applying force to a composite material, the brittle matrix cracks at low stress
levels > fibres take over
Woven fiber
Epoxy resin –polymer matrix
4
The structure & comp. of copolymeric films, plays an
important role on the final properties of modified
carbon surface
The coating parameters & characterization of these
functionalised thin films are important .
Improving the interfacial adhesion
Advanced Composites- Interfacial adhesion
control the level of fiber/matrix adhesion


A.S.Sarac,M.Serantoni,,A.M.T.Syed,V.J.Cunnane ,Appl.Surface Sci.,(2004)
229,13-18
A.S.Sarac,A.M.T.Syed,M.Serantoni,,V.J.Cunnane J.Mater.Sci.Lett.(2004)
39,2945-2950
5
Surface Analysis (the characterizations of
electrografted thin polymeric film ~10-50nm film
characterizations-Fast and simple for org. thin film
coating & charac. -Nanosize Change of functionality of surface)

Spectroscopic
Functionalities
– FTIR-ATR
– Raman
Composition
- XPS,EDX,FIBSIMS
Electrochemical Impedance Spectroscopic studies

Morphological
– SEM
– AFM
6
AFM of Electrogrowth of
P[Cz-co-AAm] onto HOPG Graphite
Higher scan rates (100 mV/s) : thin (hf  22 nm) coatings .
Lower scan rates (≤ 50 mV/s) ~50 nm
1.53 V
G4
1.04 V
0.5 mA
0.94 V
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
E (V) vs Ag/AgCl
A.Bismarck,A.Menner,J.Barner,A.F.Lee,K.Wilson,
J.Springer,J.P.Rabe,A.S.Sarac, Surface Coat .Tech. 145(2001)164-175
7
Current density vs cycle number (▪): 1.53V (●): 1.04 V
and the coating thickness (▫) from the ellipsometric angles
-3
180
7.0x10
-3
6.0x10
160
-3
140
-3
120
-3
3.0x10
100
e
4.0x10
h f / nm
i / mA/cm
2
5.0x10
-3
2.0x10
80
-3
1.0x10
60
0.0
40
2
4
6
8
10
cycle number
8
Galvanostatic vs.
Cyclic voltammetry
polymerization rate vs.film growth.
• CV :
• Galvanostatic
process
thin
coating
(hf  15 nm) & smoother (RMS = 13 nm),
9
AFM of Untreated Carbon fiber(r~5.6 μ)
polyethylenedioxythiophene
(PEDOT)
Carbon Fiber
PolyEDOT
n
O
-e
O
S
-e
S
S
O
O
O
O
O
S
O
O
O
S
S
O
O
O
O
S
10
BF4-
+
S
O
O
O
O
S
m
Polyterthiophene/CF
S
S
0.4
S
0.3
Current (mA)
0.2
-e
0.1
S
S
S
S
S
S
n
0.0
-e
-0.1
-0.2
0.25
BF4-
0.75
+
1.25
Potential (V vs. Ag/AgCl)
or PF
S
S
6
S
S
S
S
n
+
11 BF 4
Electrocoating of polytetrathiophene
onto carbon fiber by cyclic voltammetry
10mM TEABF4/MeCN. 10 cycles at 100mVs-1
0.09
70
0.07
60
0.05
50
MeCN-TBAPF6
PC-TEABF4
65
55
RMS nm (1µm2)
Current (mA)
0.11
0.03
0.01
45
40
35
30
25
20
-0.01
15
0
-0.03
50
100
-1
scan rate (mVs )
-0.05
-0.07
0.00
0.50
1.00
Potential (V vs. Ag)
1.50
2 mM Polytetrathiophene in 10 mM TEABF4 / PC ,
20 mV/s ,RMS 50 nm (1mm2) 5 scan
12
SARAC,A.S.,EVANS,U.,SERANTONI,M.,CUNNANE,V.J.,Carbon 41,14 (2003) 2725-2730
polytetrathiophene formation on the surface
Tetrathiophene
e
-
CF
2nd
S
S
S
S
3rd
.
S
S
S+
S
.
S
S
S
S
+
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
13
polymethylcarbazole
N
CH 3
N
PolyMeCz
N
N
m
Carbon Fiber
14
n
Poly[MCz] on CFME in 0.1 M NaClO4
in PC at 100 mV/s.
Current Density, A/cm
2
0.05
Poly(MCz)
0.00
-0.05
-0.10
N
-0.15
CH 3
-0.20
-0.25
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Potential, V (vs.Ag)
15
Poly[MPy] on CFME in 0.1 M NaClO4
in PC at 100 mV/s.
Current Density, A/cm
2
20
15
10
Poly(MPy)
5
N
0
CH
-5
3
-10
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Potential, V (vs.Ag)
16
Poly[MPy-co-MCz] on CFME
in 0.1 M NaClO4 in PC at 100 mV/s,
[MPy]& [MCz]=0.001 M
Current Density, /cm
2
6
4
CH3
2
*
N
0
m
n
-2
N
-4
Poly[MPy-co-MCz]
-6
0.0
0.2
0.4
0.6
0.8
1.0
CH
3
1.2
Potential, V (vs.Ag)
17
Poly[MPy-co-MCz] in monomer-free solution.
a) 10 mV/s, b) 20 mV/s, c) 50 mV/s, d) 100 mV/s, e) 200 mV/s
in a 0.1 M NaClO4 / PC solution. All samples were subsequently cycled 8
times
CH3
6
e
-1
200 mVs
4
Current Density, /cm
2
d
c
-1
50 mVs
b
a
0
m
n
-1
100 mVs
2
*
N
-1
20 mVs
N
CH
3
-1
10 mVs
-2
-4
-6
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Potential, V (vs.Ag.)
18
Anodic
Cathodic
2
4
Peak current density,A/cm
Current density, A/cm
2
Scan rate dependence of the copolymer film :
Plots of anodic and cathodic peak currents vs. the square root of
scan rate
Inset: : change in anodic and cathodic peak currents with scan rate
in monomer free solution of 0.1M NaClO4/PC
2
0
-2
4
Anodic
Cathodic
2
0
-2
-4
-6
0
50
100
Scan rate, mV s
150
200
-1
-4
-6
2
4
6
8
10
1/2
12
14
16
-1 1/2
(Scan rate) , (mV s )
Randles Selvic
ip = (2.69 x 108) n3/2 A C D1/2 ν1/2
19
Effect of feed ratio of monomers on current ,solid
state conductivity and yield.
Conductivity
% Yield
6
% Yield
40
3
30
2
20
1
10
0
0.002
0.004
0.006
[MCz]0/[MPy]0
0.008
0.010
Conductivity
4
50
0
0.000
MPy
1MPy: 1MCz
1MPy: 2MCz
1MPy: 5MCz
1MPy:10MCz
MCz
2
60
Current density, A/cm
5
5
4
3
2
1
0
0
1
2
3
4
5
6
7
8
9
Scan number
20
Comparison the peak current densities of electrogrowth of the copolymer films obtained by CV and
solid state conductivity in different monomer ratios
9
Current density
Conductivity
8
7
8
7
6
6
5
5
4
4
3
3
2
2
1
1
0
Conductivity, mS/cm
Current density, A/cm
2
9
0
0
2
4
6
8
10
[MCz]0/[MPy]0
21
Anodic peak current densities of Poly[MPy-co-MCz] in
different electrolytes using multiple (50 cycles) in
monomer-free solution at 100 mV/s,
[MPy] &[MCz]=0.001 M.
4.5
Current density, /cm
2
LiClO4
NaClO4
KClO4
4.0
3.5
3.0
2.5
2.0
1.5
0
10
20
30
40
50
Scan number
22
Poly(N-vinylcarbazole-co-Vinylbenzenesulfonic acid)
•Ungrafted CF,
P[NVCz-co-VBSA] grafted CF
•100 mA 4 hrs
•200mA 2 hrs
CH = CH 2
N
CH = CH 2
Element
C
N
O
S
SO 3-
NVCzVBSA2
76.57
2.843
2.84
15.20
15.2
2.825
2.83
NVCzVBSA3
85.83
3.76
9.033
9.03
0.147
0.15
23
Poly[NVCz-coVBSA]
NVCzVBSA3
(b)
N
N
O
S
O
O
O
S
O
O
N
(c)
O
S
O
S
O
O
O
O
Poly[NVCz-co-VBSA]
24
Reflectance FTIR of thin
carbazole copolymer film on CF
102,21
[MeTh]/[Cz]= 2.75
101,5
101,0
1644,09
3778,36
3667,54
1227,54
[3-MeTh]/[Cz] =1.5
100,5
2343,00
100,0
in 0.1 M TMAP/DMF
3783,64
99,5
808,36
745,09 639,63
1464,81
3662,26
99,0
98,5
2459,10
3044,85
98,0
%T 97,5
808,81
2163,58
2928,75
[MeTh]/[Cz]= 1.0
1385,72
1269,72
97,0
CH3
96,5
1312,49
1665,11
946,87
96,0
S
95,5
622,38
95,0
1229,48
94,5
94,0
N
P[3-MeTh-Cz]
1454,27
H
93,5
746,32
93,17
4000,0
3600
3200
2800
2400
2000
1800
cm-1
1600
1400
1200
1000
800
550,0
25
Poly[Methylthiophene-cocarbazole]
CH 3
S
N
H
26
Reflectance FTIR & EDX of
electrografted P[MeTh-co- Cz] thin
copolymer film
N
H
MeTh-Cz
MeTh-Cz
MeTh-Cz
MeTh-Cz
C
MeTh-Cz 7
4000
5
6
7
8
MeTh-Cz 5
3000
MeTh-Cz 8
2000
MeTh-Cz 6
1000
O
S
Cl
0
0
1
2
3
keV
CH3
A.S.Sarac,
J.Springer., Surface Coat.Tech.(2002) 160,227-238
S
N
H
27
Raman Spectra
1330 cm-1 C=C , 1567cm-1 C-C ring
28
XPS
C=S
C-N
C=O
P[Cz-co-MeTh] Carbon fiber
at different initial comonomer feed ratios
A.S.Sarac,
M.Serantoni, T.Syed, J.Henry, V.J.Cunnane, J.B.McMonagle,
Appl.Surface Sci.. 243(1-4)( 2005) 183-198
A.S.Sarac, A.MT.Syed, M.Serantoni, J.Henry, V.J.Cunnane, J.B.McMonagle.
Appl.Surface Sci. Sci.222,1-4(2004) 148-165
29
Reflectance FTIR of vinyl group
in copolymer
CH3
102,10
S
101,5
808,36
N
101,0
3778,36
3667,54
1644,09
P[3-MeTh-Cz]
H
100,5
1464,81
745,09
1227,54
639,63
Hexel AS4C in 0.1 M TMAP/DMF
2343,00
100,0
P[3-MeTh-NVCz]
%T
99,5
2306,06 2063,32
3050,13
2923,48
3298,15
99,0
2627,96
658,09
618,54
CH3
805,72
98,5
1322,45
1380,45
S
1478,00
98,0
97,5
1222,27
1058,81
1449,00
N
721,36
1151,09
1093,09
1651,28
747,61
96,98
4000,0
3600
3200
2800
2400
2000
1800
cm-1
1600
1400
1200
1000
800
550,0
30
Poly[MeTh-co-NVCz]
CH 3
S
CH 3
N
S
31
CH = CH 2
Electrocoated carbon fibre single fibre pull-out test.
a)The fibre was partially pulled-out of the electrodeposited
coating.
b) fibre completely pulled-out of the electrodeposited coating.
The adhesive strength CF/PMMA matrix resulted in 100% improved in thin and
homogeneous PMMA coatings.
(the interfacial shear strength not so good in thicker coatings)
So, electrocoating of MMA can improve the interfacial performance of
a carbon fibre reinforced PMMA model composite.
32
% concentration (determined from XPS ) versus cps (determined
from FIBSIMS measurements ) P[NVCz-co-MeTh]
C
O
90
85
% Concentration (XPS)
80
75
70
65
25
20
15
10
5
80
100
120
140
160
180
200
220
cps (FIBSIMS)
M.Serantoni, A.S.Sarac,D.Sutton,V.J.Cunnane, Surface Coat.Tech..( 2005) (in
33 press)
Nanosize Surface chemistry & Morphology
of CP electrografting onto Carbon Foam & CF
surface &Electrochemical Impedance
Their Applications

Thin conductive polymer films can be covalently
electrografted onto the CF
 Surface structure and composition can be analysed in
nanoscale (> 20 nm)(XPS,Raman ,FTIRATR)
 Surface morphology (SEM,AFM)
 improve the interfacial shear strength
 reinforcement appl.
 biosensor applications
34
Istanbul Bosphorous
Asia-Europe
sarac@itu.edu.tr
http://atlas.cc.itu.edu.tr/~sarac/
http://www.kimya.itu.edu.tr/saraca/
35