A new imine coupled pyrrole-carbazole-pyrrole polymer: Electro-optical properties and electrochromism

Article abstract of DOI:10.1016/j.polymer.2010.02.020

In this study, imine bond coupled pyrrole-carbazole-pyrrole monomers were synthesized in four steps and then directly polymerized onto ITO/glass surface via potentiodynamic electrochemical process. Electrochemical and optical bad gap of these monomers and polymers were calculated by using cyclic voltammetry and UV-Vis absorption spectroscopy. Conductivity of the polymers with different alkyl side-chain was determined by using four point probe technique. Length of the side-alkyl chain influence iodine doping and also conductivity of polymers. As a result of the spectroelectrochemical measurements, the orange color of film changed to green color with applied potential and the polymer was found to be suitable material for electrochromic applications.

Full text of DOI:10.1016/j.polymer.2010.02.020

Polymer 51 (2010) 1663e1669
Contents lists available at ScienceDirect
Polymer
journal homepage: www.elsevier.com/locate/polymer
A new imine coupled pyrroleecarbazoleepyrrole polymer: Electro–optical
properties and electrochromism
Ozde Deniz Is , Fatma Baycan Koyuncu , Sermet Koyuncu ,*, Eyup Ozdemir
a
a
b
a,
**
a
Department of Chemistry, Faculty of Sciences and Arts, Çanakkale Onsekiz Mart University, 17020 Canakkale, Turkey
Çan Vocational School, Çanakkale Onsekiz Mart University, 17400 Çanakkale, Turkey
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 8 December 2009
Received in revised form
In this study, imine bond coupled pyrroleecarbazoleepyrrole monomers were synthesized in four steps
and then directly polymerized onto ITO/glass surface via potentiodynamic electrochemical process.
Electrochemical and optical bad gap of these monomers and polymers were calculated by using cyclic
voltammetry and UVeVis absorption spectroscopy. Conductivity of the polymers with different alkyl
side-chain was determined by using four point probe technique. Length of the side-alkyl chain influence
iodine doping and also conductivity of polymers. As a result of the spectroelectrochemical measure-
ments, the orange color of film changed to green color with applied potential and the polymer was found
to be suitable material for electrochromic applications.
5
February 2010
Accepted 10 February 2010
Available online 16 February 2010
Keywords:
Carbazole
Pyrrole
Ó 2010 Elsevier Ltd. All rights reserved.
Imine polymers
1. Introduction
a dialdehyde [9,10] and oxidative polymerization of imine mono-
mers with electron rich terminal heterocycle such as thiophene
In comparison to the inorganic semiconductors, conducting
polymers containing conjugated double bonds along the backbone
are useful materials because of their flexibility, lightness of weight,
ease of fabrication and chemical inertness. Due to these useful
properties, they have been investigated as the materials of elec-
tronics, optoelectronics, and photonics. These polymers are also
potential candidates for a wide variety of commercial applications
ranging from catalysts for photo-electrochemical processes, elec-
trode materials, microelectronic devices, and organic batteries to
electrochromic display devices [1].
[7,11], carbazole [12] and pyrrole [6,13] etc.
Thanks to carbazole can be easily functionalized on the 3,6- [14],
2,7- [15], or N-positions [16], it is covalently linked into polymeric
systems, both in the main chain [17] as building blocks and in
a side-chain as pendant group [18], and its good hole transporting
ability, high thermal and photo-electrochemical stabilities, carba-
zole containing polymers have played a very important role in
organic photo-electronic technology products such as organic light
emitting diodes [19,20], organic photovoltaic cells [21,22] and
electrochromic devices [23,24] etc. Besides, like carbazole, poly-
pyrrole is one of the most stable among known conducting poly-
mers, and its thin and plastic film has many possible applications
such as capacitors, electrochromic devices, anti-corrosive coatings,
batteries, actuators and sensors [25]. Due to the ease of formation
of relatively stable radical cations (polarons), pyrrole readily poly-
merizes at oxidative polymerization process both chemically [26]
and electrochemically [27]. Since polypyrrole was first electro-
chemically synthesized about three decades ago by Diaz et al. [28],
its properties and applications have been intensively investigated
by now.
Due to the eCH]Ne group isoelectronic with the eCH]CHe
group, imine polymers incorporated of nitrogen atoms into the
conjugated system have another approach to form classes of
materials with equally interesting electronic and optical properties
[2,3]. These polymers have industrial applicability such as light
emitting diodes, thin film transistors, electrochromic devices and
photovoltaic cells because of useful semiconducting and optoelec-
tronic properties as well as high thermal stability and good
mechanical strength [3e8]. Aromatic polyazomethines are usually
synthesized via both polycondensation of an aromatic diamine and
Although, some of pyrroleeimine polymers were prepared via
electrochemically [6] and chemically [13,29] oxidative process in
the literature before, this is the first study about imine polymers
having pyrrole and carbazole as second electroactive moiety in the
main chain, and also electrochemical, optical and electrochromic
properties of these polymers having different side-alkyl chain were
*
Corresponding author. Tel./fax: þ90 286 4167706.
** Corresponding author. Tel.: þ90 286 2180018; fax: þ90 286 2180533.
E-mail addresses: sermetkoyuncu@hotmail.com, skoyuncu@comu.edu.tr
(
S. Koyuncu), eozdemir@comu.edu.tr (E. Ozdemir).
0
032-3861/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.polymer.2010.02.020

1664
O.D. Is et al. / Polymer 51 (2010) 1663e1669
ꢀ
intensively investigated. Further conductivity was measured by
using a four point probe technique. It is observed that conductivity
was changed by length of the side-alkyl chain and iodine doping.
mixture under reflux for 3 h at 70 C. The precipitate was collected
by filtration, re-crystallized from n-heptane and then dried in
vacuum desiccator. Yield: PK-1: 76%; PK-2: 72%.
UVeVis (
(NeH amine) 3432; (CeH aromatic) 3068, 3022; (CeH aliphatic)
916, 2850; (eCH]Ne, imine), 1620; (C]C phenyl) 1605, 1578,
lmax) (CHCl
3
): 252, 284, 312 and 352 nm. FT-IR (cmꢁ1):
2
. Experimental
2
1
2.1. Materials
1423. H NMR (CHCl
3
-d):
d
ppm, 8.48 (s, 2H, eCH]Ne); 6.72 (d, 2H,
AreHaa ); 6.93 (d, 2H, AreHcc ); 7.42 (d, 2H,AreHff ); 6.33 (t, 2H,
0
0
0
0
0
0
All chemicals was purchased from Aldrich, Alfa Aesar and Merck
AreHbb ); 7.99 (d, 2H, Hdd ); 7.42 (t, 2H, Hee ); 4.33 (t, 2H,
eNeCH e); 1.96e1.30 (CeH aliphatic; for N-decyl-Carb (PC-2));
1.38 (t, 3H, ReCH ; for N-ethyl-carb); 1.00 (t, 3H, ReCH ; for N-
decyl-Carb). C NMR (CHCl -d): ppm, 148 (eCH]Ne), 124, (C1);
110, (C2); 120, (C3); 131, (C4); 144, (C5); 116, (C6); 109, (C7); 140,
and used without further purification. The syntheses and charac-
terizations of 9H-N-alkylcarbazole (1), 3,6-dinitro-9H-N-alkylcar-
bazole (2) and 3,6-diamino-9H-N-alkylcarbazole (3) were prepared
according to published procedure by Koyuncu et al. [7].
2
3
3
13
3
d
(C8); 112, (C9); 123, (C10); 43, (NeCH
2
2 2 n
); 34e21, (NeCH e(CH ) );
0
14, (CH eCH ) (Scheme 1 and 2).
2
3
2
.2. General procedure for synthesis of 9-alkyl-N,N -bis-(1H-
pyrrole-2-yl-methylene)-9H-carbazole-3,6-diamine (PCs)
0
2
.3. Electrochemical polymerization of 9-alkyl-N,N -bis-(1H-
0
9
-Alkyl-N,N -bis-(1H-pyrrole-2-yl-methylene)-9H-carbazole-
pyrrole-2-yl-methylene)-9H-carbazole-3,6-diamine (poly-PC-1)
3
,6-diamine (PC) were prepared from the condensation of 2-pyr-
rolecarboxaldehyde (20 mmol) with 3,6-diamino-9-N-alkylcarba-
zole (10 mmol) in methanol (20 mL) achieved by boiling the
Electrochemical measurements were performed using
a CHI660B electrochemical workstation from CH Instruments
ꢁ
3
(
(
Austin, TX, U.S.A.). Monomer of PC-1 or 2 (2 ꢂ 10 M) and pyrrole
ꢁ3
2 ꢂ 10 M) were covered on Pt and ITO/glass electrode surfaces by
applying potentials ranging between ꢁ0.5 V and þ1.5 V in 0.1 M
NaClO /LiClO as supporting electrolyte at 100 mV/s as scan rate by
4
4
electrochemical method (Schemes 3 and 4). Polymer film of PCs on
ITO/glass surface was also dedoped electrochemically in monomer
free-electrolyte solution. Further, to investigation of the UVeVis
and CV measurements, the polymers can be partly dissolved in
2 2
CH Cl by using ultrasonic bath.
2.4. Instrumentation
FT-IR spectra were recorded by a Perkin Elmer FT-IR Spectrum
ꢁ
1
1
13
One by using ATR system (4000e650 cm ). H and C NMR
ꢀ
(
Bruker Avance DPX-400) data recorded at 25 C by using CHCl
3
-
Scheme 1.
d as solvent and TMS as internal standard. Electrochemical
Scheme 2.

O.D. Is et al. / Polymer 51 (2010) 1663e1669
1665
H
H
)
N
N
H
H
(
N
N
C
N
N
C
H
H
C
H
N
C
H
N
electrochemical polymerization
N
R
N
R
Scheme 3.
)
H
N
H
(
)
N
H
(
N
H
H
)
N
H
(
N
N
C
N
N
C
H
N
H
H
C
H
N
C N
electrochemical co-polymerization
+
H
N
R
N
R
Scheme 4.
measurements were carried out by CH instruments 660B cyclic
voltammetry. The electrochemical cell consists of an Ag wire as
reference electrode (RE), Pt wire as counter electrode (CE) and
NMR and compiled in the Experimental section. Finally, these
results indicate that all reactions were completed successfully.
6
platinum as working electrode (WE) immersed in 0.1 M TBAPF as
3.2. Optical and electrochemical properties
the supporting electrolyte. All measurements were carried out
under argon atmosphere. The potentials were calibrated to the
3
The UVeVis spectra were recorded in CHCl solution (Fig. 1).
þ
ferrocene redox couple E(Fc/Fc ) ¼ þ0.41 V. The electrochemical
These compounds showed multi absorption peak attributed to
* and n / * transition of the pyrrole, carbazole and imine
moieties. Due to enlargement of conjugation, the red shift is
observed at the end of the polymerization. Absorption maximum
max) of poly-PC-2 at 378 nm exhibits about a 20 nm red shift as
HOMOeLUMO energy level of synthesized monomer and polymer
p
/
p
p
were calculated from their oxidation and reduction onset values
p
/ p
[
30].
UVeVis absorption spectra were measured by Jena Speedcord S-
00 diode-array spectrophotometer. The absorption spectra of
these compounds were recorded in both CHCl (liquid phase) and
ITO/glass transparent film (solid phase). The optical band gaps (E
(l
6
compared to PC-2. This shift was also observed in the poly-PC-1. On
the other hand, McCullough claimed that the length of the alkyl
substituents affects on the absorption maximum and bang gap due
to solvation is promoted with increase in the length of the alkyl
3
g
)
of PC monomers and polymers were calculated from their
absorption edges [31]. We used the data obtained from UVeVis
spectra and cyclic voltammetry for spectroelectrochemical
measurements of poly-PC-1 on ITO/glass transparent film. These
measurements were carried out to consider absorption spectra of
side-chain, leading to expanded chain structure with longer
p
conjugation [32,33]. Because of this effect, about 3e5 nm red shift
were observed on the absorption maximum and bang gap with the
increasing the alkyl side-chain.
The electrochemical properties of PC monomer and the poly-
mers were investigated by cyclic voltammetry (CV). Due to having
the same electroactive units in their structure, all PC monomers and
polymers show similar electrochemical behavior. As a result of CV
this polymer film under applied voltage and 0.1 M NaClO
4 4
/LiClO in
CH CN was used as supporting electrolyte. The spectroelec-
3
trochemical cell includes a quartz cuvette, an Ag wire (RE), Pt wire
counter electrode (CE) and ITO/glass as transparent working elec-
trode (WE). Conductivity was measured on the ITO/glass surface
coated PC polymers and carried out by using a Keithley 2400
electrometer. Iodine doping was carried out by exposure of the
films to iodine vapor at atmospheric pressure and room tempera-
ture in a desiccator.
3
. Results and discussion
3.1. Synthesis and characterization
The initial compounds (1, 2, 3) were synthesized and fully
characterized by Koyuncu et al. in the previous studies [7]. The final
products, imine monomers containing pyrrole and N-alkylcarba-
zole (PC-1, PC-2) moieties, synthesized by the condensation reac-
tion of 3,6-diamino-9-N-alkylcarbazole (3) compounds and
2
-pyrrolecarboxaldehyde. Synthesized compounds were purified
by column chromatography and re-crystallization from n-heptane.
Structure of final product was also fully identified by using FT-IR, H
1
Fig. 1. UVeVis spectra of synthesized monomers and polymers.

1666
O.D. Is et al. / Polymer 51 (2010) 1663e1669
Fig. 3. Repeated potential scan of PC-1-pyrrole between
LiClO eNaClO eacetonitrile, scan rate 100 mV/s.
0 and 1.6 V in 0.1 M
4
4
agreement. This is resulted that the electroactive centers and
photoactive centers behave independent from each other for
synthesized molecules.
3.3. Electrochemical polymerization and electrochromic properties
Conjugated aromatic molecules such as pyrrole, thiophene,
Fig. 2. Cyclic voltammogram of (a) PC-2 and (b) poly-PC-2 in the TBAPF
6
eacetonitrile,
scan rate 100 mV/s, AgeAgCl.
furan, etc. can be easily oxidized and deposited as electroactive
polymer films onto the ITO/glass surface by repeated anodic scans
[34]. Pyrroleeimine compounds have a low oxidation potential
measurements (Fig. 2), in the negative regime, the irreversible peak
which reflect the reduction of imine (eCH]Ne) with peak poten-
tial of ꢁ1.98 and ꢁ1.90 were observed for radical anion formation of
PC-2 and poly-PC-2, respectively. Due to PC-2 polymer have not
uniform structure than that of PC-2 monomer, the imine reduction
peak of the polymer was broadened and slightly shifted to posi-
tively. The same effect was observed between PC-1 and poly-PC-1.
On the other hand, during anodic scan, two irreversible oxidation
peaks of PC-2 were observed attributed to pyrrole at 1.01 V and
carbazole at 1.51 V, respectively. Besides, solvation is promoted with
increase in the length of the alkyl side-chain, leading to expanded
þ
(z0.8 eV against Ag/Ag electrode) than that of thiophene or furan
imine derivatives, so that they can be easily polymerized by the
electrochemical process. Because of having low oxidation potential,
pyrroleeimine compounds don't need a co-monomer except from
the others. In this study, when the co-monomer wasn't utilized, PC
monomers were polymerized on the ITO/glass surface but didn't
show any reversible redox behavior and electrochromic effect. For
the electrochromic applications, pyrrole was used as the co-
monomer for electro polymerization of PC-1. By the repeated
anodic scan, the constant increase of the peak current indicates that
the monomers become more repeated in the polymer backbone
and a regular amount of polymer is coated on the electrode after
each new sweep. Due to aromatic conjugation becomes more
pronounced, these peaks broadened and slightly shifted to lower
potential at the end of the polymerization. Electro polymerization
of PC-1 in the presence of pyrrole was presented in Fig. 3 and
Scheme 4.
chain structure with longer
p conjugation Because of enlargement
of conjugation, oxidation of poly-PC-2 was observed at lower
p
potentials compared to PC-1. Thus, oxidation of poly-PC-2 was
observed at lower potential than that of poly-PC-1. Finally,
HOMOeLUMO energy levels, electrochemical and optical band gap
values of the PC monomers and polymers were calculated. It is
concluded that synthesized polymer oxidized at significantly lower
potentials than that of imine polymer of thiopheneecarbazole
derivative [6] and thus having lower HOMOeLUMO band gap. As
seen from Table 1, in comparison to electrochemical and optical
band gap of all monomers and their polymers, the values are not
Spectroelectrochemical measurements investigate the changes
in optical properties of conducting polymers upon applied voltage.
These measurements showing the formation of polaronic species of
poly-PC-1 molecule on the ITO/glass surface were studied by
Table 1
'
HOMO and LUMO energy levels, electrochemical (E ) and optical band gaps (E
g
) values of PC monomers and polymers.
'
g
Compounds
Reduced groups and
peak potentials (V)
Oxidized groups and
peak potentials (V)
HOMO (eV)
LUMO (eV)
ðE Þ, Electrochemical
g
(E ), Optical band
gap (eV)
g
band gap (eV)
eHC]Ne (imine)
Pyrrole (Ring)
Carbazole (Ring)
PC-1
PC-2
poly-PC-1
poly-PC-2
ꢁ1.99
ꢁ1.98
ꢁ1.92
ꢁ1.90
þ1.02
þ1.01
þ0.84
þ0.81
þ1.50
þ1.51
þ1.51
þ1.50
ꢁ5.28
ꢁ5.28
ꢁ5.01
ꢁ4.98
ꢁ2.67
ꢁ2.67
ꢁ2.77
ꢁ2.81
2.62
2.61
2.24
2.17
2.90
2.87
2.76
2.69

O.D. Is et al. / Polymer 51 (2010) 1663e1669
1667
Fig. 4. Spectroelectrochemical measurements of poly-(PC-1-pyrrole) film.
Fig. 6. Change in the electrical conductivities of PC polymers during the process of
ꢀ
iodine doping (done at atmospheric pressure and 25 C).
applying potentials ranging between ꢁ0.6 V and 1.6 V in monomer
4 4
free acetonitrile/LiClO eNaClO (0.1 M) medium. The appearance of
broad band around 950 nm could be attributed to the evolution
of polaronic species. As can be seen from Fig. 4, the orange color of
film at neutral state was changed to green by the oxidation.
Electrochromic parameters of poly-PC-1 film were analyzed by
changes that occurred in the transmittance (increments and
decrements of the absorption band at 950 nm with respect to time)
while switching the potential step wisely between neutral (ꢁ0.6 V)
and oxidized states (þ1.6 V) with a residence time of 10 s. Double
potential step chronoamperometry was carried out to estimate the
response time of the polymer film. During the experiment, the 12%
transmittance at the wavelength of maximum contrast was
measured by using a UVeVis spectrophotometer. The oxidation and
reduction response times were calculated as about 3 s. Optical
activity of the film was retained by 74.6% even after 1000 cycles of
operation, signifying reasonable redox stability. Despite having
a relatively slow response and low contrast ratio, co-polymer of
poly-PC-1 with pyrrole shows reversible redox behavior, resistance
to over oxidation and thus it can be useful for electrochromic
applications (Fig. 5).
these results have shown that the dopant interacts with the double
bond in the polymer backbone and forms a polaronic state (radical
cation) as an electron is transferred from the double bond to the
dopant creating a hole or a positive carrier at the double bond site.
These holes or positive carriers are responsible for the electrical
conduction in these materials [35]. Conductivity measurements of
poly-PC's were carried out with an electrometer using a four point
probe technique. Fig. 6 shows the electrical conductivity behavior
results of poly-PC-1 and poly-PC-2 molecules under iodine doping
ꢀ
in varying periods at 25 C. First of all, conductivities of PC-1 and
ꢁ7
ꢁ8
PC-2 polymers were found to be approximately 10 e10 S/cm
and then an increase were observed after iodine doping. Conduc-
tivity measurements carried out at the end of each doping period.
Despite the polymers have same electroactive moiety (pyrrole and
carbazole), poly-PC-1 showed lower conductivity than that of poly-
PC-2. These differences are assumed to be caused by the different
side-alkyl chain substituted on the carbozyl nitrogen. While poly-
PC-1 reached maximum conductivity value within 2 days, poly-PC-
2
reached within 4 days. This result explains that steric effect of
poly-PC-1 is less than poly-PC-2. Also, these alkyl groups hinder the
ꢁ
3.4. Conductivity
coordination of I
3
with nitrogen, because of the steric effect exerted
by them. Since nitrogen is a very electronegative element and is
ꢁ
Conductivity is related to both intermolecular and intra-
capable of coordinating with the
I
3
,
Diaz et al. suggested
molecular electron transfer on the polymer backbone. Therefore
a conductivity mechanism of imine (eCH]Ne) polymers when
Fig. 5. Electrochromic switching, optical absorbance monitored for poly-(PC-1-pyrrole) film at 950 nm (0.6e1.6 V).

1668
O.D. Is et al. / Polymer 51 (2010) 1663e1669
)
H
N
(
N
)
(
H
H
)
N
H
(
N
N
C
H
C
H
N
N
R
Iodine Doping
)
H
(
)
N
)
(
N
H
)
H
(
N
)
(
H
)
N
H
H
N
N C
H
H
(
N
(
N
)
)
H
(
N
H
N
H
(
H
N
N C
H
)
C
H
N
N
H
(
N
N
C
H
C
H
N
N
R
C
H
N
N
R
N
R
I
I
I
I -
I
I -
I
I
I -
Scheme 5.
doped with iodine [36]. Furthermore, it is believed that iodine
doping occurs not only on the nitrogen atoms but also on the
pyrrole or carbazole rings. The conductivity mechanism over the
polymer backbone can be proposed as Scheme 5.
References
[
1] Wallace GG, Spinks GM, Kane-Maguire LAP, Teasdale PR. Conductive electro-
active polymers: intelligent materials systems. CRC Press; 2003.
2] Grigoras M, Antonoaia NC. Polym Int 2005;54:1641.
3] Yang CJ, Jenekhe SA. Chem Mater 1991;3:878.
[
[
[
[
4] Yang CJ, Jenekhe SA. Macromolecules 1995;28:1180.
5] J-Cho S, Kimoto A, Higuchi M, Yamamoto K. Macromol Chem Phys
2005;206:635.
4
. Conclusion
[
[
6] Tarkuc S, Sahin E, Toppare L, Colak D, Cianga I, Yagci Y. Polymer 2006;47:
2
001.
7] Koyuncu S, Kaya I, Baycan Koyuncu F, Ozdemir E. Synth Met 2009;159:
034.
The synthesis and electrochemical polymerization of a two
_
imine coupled PC monomers with different side-alkyl chain is
reported. Due to the same electroactive moiety, these molecules
show similar electrochemical and optical behaviors but different
conductivities. It is observed that length of the side-alkyl chain
influenced the oxidationereduction potential and absorption
maximum of the PC polymers. As a result of spectroelectrochemical
investigation, the orange color of the film on the ITO/glass surface
prepared via electro-oxidative polymerization changed into green
color during the p- doping process. In addition, kinetic study
exhibited that poly-(PC-1-pyrrole) has reasonable stability on
transparent ITO/glass surface. Owing to the stable electrochromism
and reversible color changes, the PC polymers can be candidate for
design of organic electrochromic devices (OECD).
1
_
[8] Koyuncu S, Kus M, Demic S, Kaya I, Ozdemir E, Icli S. J Polym Sci Part A Polym
Chem 2008;46:1974.
[
9] Grigoras M, Catanescu CO. J Macromol Sci Part C Polym Rev 2004;C44:131.
10] Iwan A, Sek D. Prog Polym Sci 2008;33:289.
[11] Zotti G, Randi A, Destri S, Porzio W, Schiavon G. Chem Mater 2002;14:4550.
[
[
[
[
12] Grigoras M, Antonia MC. Eur Polym J 2005;41:1079.
13] Simuonescu CI, Grigoras M, Cianga I, Olaru N. Eur Polym J 1998;34:891.
14] Han F, Chi L, Liang X, Ji S, Liu S, Zhou F, et al. J Org Chem 2009;74:1333.
[15] Bloudin N, Leclerc M. Acc Chem Res 2008;41:1110.
[
16] Watanabe M, Nishiyama M, Yamamoto T, Koie Y. Tetrahedron Lett
000;41:481.
17] Chen JP, Natansohn A. Macromolecules 1999;32:3171.
2
[
[18] Bubniene G, Malinauskas T, Getautis V, Stanisauskaite A, Jankauskas V,
Sidaravicus J. Synth Met 2006;158:670.
[19] Michinobu T, Kumazawa H, Otsuki E, Usui H, Shigehara K. J Polym Sci Part A
Polym Chem 2009;47:3880.
[20] Lin S-L, Chan L-H, Lee R-H, Yen M-Y, Kuo W-J, Chen C-T, et al. Adv Mater
2008;20:3947.
[
[
21] Li J, Dierschke F, Wu J, Grimsdale AC, Müllen K. J Mater Chem 2006;16:96.
22] Wang ZS, Koumura N, Cui Y, Takahashi M, Seguchi H, Mori A, et al. Chem Mater
Acknowledgement
2008;20:3993.
[
[
23] Beaupre S, Breton A-C, Dumas J, Leclerc M. Chem Mater 2009;21:1504.
24] Koyuncu S, Gultekin B, Zafer C, Bilgili H, Can M, Demic S, et al. Electrochim
Acta 2009;54:5694.
We gratefully acknowledge the supports from Çanakkale
Onsekiz Mart University Grants Commission (Project Number:
2
009/18).
[25] Soloducho J. Synth Met 1999;99:181.

O.D. Is et al. / Polymer 51 (2010) 1663e1669
1669
[
[
[
[
26] Pickup PG, Osteryoung RA. J Am Chem Soc 1984;106:2294.
[31] Bredas JL. J Chem Phys 1985;82:3808.
[32] McCullough RD. Adv Mater 1998;10:93.
[33] Shin C-K, Lee H. Synth Met 2004;140:177.
[34] Satoh M, Imanishi K, Yoshino K. J Electroanal Chem 1991;317:139.
27] Khulbe KC, Mann RS, Khulbe CP. J Polym Sci Part A Polym Chem 1982;20:1089.
28] Diaz AF, Kanazawa KK, Gardini GP. J Chem Soc Chem Commun 1979;14:635.
29] Simionescu CI, Cianga I, Ivanoiu M, Airinei A, Grigoras M, Radu I. Eur Polym J
1
999;35:1895.
30] Wudl F, Kobayashi M, Colaneri N, Noysel M, Heeger AJ. Mol Cryst Liq Cryst
985;118:199.
[35] Shirakawa H, Louis EJ, Macdiarmid AG, Chiang CK, Heeger AJ. J Chem Soc Chem
Commun; 1977:579.
[36] Diaz FR, Moreno J, Tagle LH, East GA, Radic D. Synth Met 1999;100:187.
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