Synthesis and properties of an ionic polyacetylene: Poly(dimethylphenylpropargylammonium bromide)

Article abstract of DOI:10.1080/15421400903584325

A monosubstituted ionic polyacetylene having a quaternary ammonium salt was synthesized and characterized. The polymerization of dimethylphenylpropargylammonium bromide (DMPPAB) was performed by various transition metal catalysts to give the resulting pol

Full text of DOI:10.1080/15421400903584325

Mol. Cryst. Liq. Cryst., Vol. 520: pp. 158=[434]–164=[440], 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 1542-1406 print=1563-5287 online
DOI: 10.1080/15421400903584325
Synthesis and Properties of an Ionic Polyacetylene:
Poly(dimethylphenylpropargylammonium bromide)
WON-CHUL LEE,1 SUNG-HO JIN,2
JONG-WOOK PARK,3 WON SEOK LYOO,4
YEONG-SOON GAL,5 AND SUHKMANN KIM6
1Department of Textile and Fashion Technology, Kyungil University,
Gyeongsan, Korea
2Department of Chemistry Education, Pusan National University,
Busan, Korea
3Department of Chemistry, Center for Nanotech. Res., The Catholic
University, Bucheon, Korea
4School of Textiles, Yeungnam University, Gyeongsan, Korea
5Polymer Chemistry Laboratory, College of Engineering, Kyungil
University, Gyeongsan, Korea
6Department of Chemistry and Chemistry Institute for Functional
Materials, Pusan National University, Busan, Korea
A monosubstituted ionic polyacetylene having a quaternary ammonium salt was
synthesized and characterized. The polymerization of dimethylphenylpropargylam-
monium bromide (DMPPAB) was performed by various transition metal catalysts
to give the resulting polymer in high yield. The polymer structure was characterized
by various instrumental methods to have a conjugated polymer backbone system
having the designed substituent. This polymer was mostly soluble in organic solvents.
The electrochemical properties of poly(DMPPAB) were measured and discussed.
Keywords Conjugated polymer; cyclovoltamogram; dimethylphenylpropargyl-
ammonium bromide; polyacetylene; transition metal catalyst
Introduction
Considerable progress has been made in the synthesis and applications of oligomers
and polymers having a p-conjugated backbone [1–7]. These conjugated organic
materials are expected to show unique properties such as electrical conductivity,
paramagnetism, migration and transfer of energy, color, and chemical reactivity
and complex formation ability [1,8]. Because of these properties, polyacetylene
Address correspondence to Won-Chul Lee, Department of Textile and Fashion Tech-
nology, Kyungil University, Gyeongsan, Gyeongsangbuk-Do 712-701, Korea. E-mail: wclee@
kiu.ac.kr and Suhkmann Kim, Department of Chemistry and Chemistry Institute for
Functional Materials, Pusan National University, Busan 609-735, Korea. E-mail: suhkmann@
pusan.ac.kr
158=[434]

Synthesis and Properties of an Ionic Polyacetylene
159=[435]
Figure 1. The chemical structure of poly(DMPPAB).
and its homologues have been promising materials for photovoltaics, displays, lasers,
nonlinear optical materials, membranes for gas separation and for liquid-mixture
separation and chemical sensors [4–7,9–13].
Polyelectrolytes are charged macromolecules containing a large number of ioniz-
able or ionic groups. The natural polyelectrolytes have been used in water-cleaning
processes for centuries. The very building blocks of life, the nucleic acids and pro-
teins, are polyelectrolytes. Synthetic polyelectrolyte have been and continue to be
a very active of scientific research and commercial growth [14].
Such ionic polyacetylenes as poly(propiolic salt)s [15], triethylammonium salt of
poly(6-bromo-1-hexyne) [16], poly(propargylammonium salt)s and poly(dipropargy-
lammonium salt)s [17–19] were reported. We have prepared a new family of substi-
tuted polyacetylenes that retain extensive conjugation. They were prepared through
the activated polymerization of ethynylpyridines by using the functional alkyl halides
[13,20–23]. And also, we have also prepared various ionic conjugated polymers having
different functionalities from the transition metal-catalyzed polymerization of ionic
acetylenic monomers [24,25]. Because the conjugated polymers contain extensive con-
jugation and ionic nature, this ionic polyacetylene family has potentials as material
candidates for mixed ionic and electronic conductivity, energy storage devices such
as batteries, permselective membrane, and light-emitting devices [1,26,27].
Now, we report the synthesis of a new ionic polyacetylene derivative with quat-
ernary ammonium salt via the transition-metal catalyzed polymerization of
DMPPAB and the characterization of the resulting poly(DMPPAB)] (Fig. 1).
Experimental
PdCl2 (99.9þ%), RuCl3, and (bicyclo[2.2.1]hepta-2,5-diene)-dichloropalladium (II)
[(NBD)PdCl2] were purchased from Aldrich Chemicals and used as received.
DMPPAB was prepared by the reaction of propargyl bromide and dimethylpheny-
lamine in acetonitrile as reported method (yield: 81%) [18]. DMPPAB was purified
by the recrystallization from ethanol-ether. The solvents were analytical grade mate-
rials. They were dried with an appropriate drying agent and distilled.
A typical synthetic procedure of poly(DMPPAB) is as follows: In a 20 mL
reactor equipped with rubber septum, 1.0 g (4.16 mmol) of DMPPAB, 0.037 g

160=[436]
W.-C. Lee et al.
(0.139 mmol, M=C ¼ 30) of (NBD)PdCl2, and 7 mL of DMF were added in that
order given. Then the polymerization was carried out at 80ꢀC for 24 hrs under nitro-
gen atmosphere. As the polymerization proceeds, the reaction solution became into
viscous dark-red solution. After the polymerization time, the polymer solution
diluted with 10 mL DMF was precipitated into a large excess of ethyl ether. The pre-
cipitated polymer was filtered and dried in vacuum oven at 40ꢀC for 24 hrs. The
black polymer powder was obtained in 83% yield.
FT-IR spectra were obtained with a Bruker EQUINOX 55 spectrometer using a
KBr pellet. NMR (1H- and 13C) spectra were obtained in DMSO-d6 solutions at
room temperature using a Varian 500 MHz FT-NMR spectrometer (Model: Unity
INOVA) and the chemical shifts are reported in ppm units with tetramethylsilane
as an internal standard. The inherent viscosities of polymers were determined at a
concentration of 0.5 g=dL in DMF at 30ꢀC. X-ray diffractograms were obtained with
a PHILLIPS X-ray diffractometer (Model: Xpert-APD). The optical absorption
spectra were measured by a HP 8453 UV-VIS-NIR spectrometer. Redox potential
of the polymer was determined by cyclic voltammetry (CV) using an EG&G 362 elec-
trochemical workstation with a scanning rate of 100 mV=s or various scan rate from
30 to 150 mV=s. The synthesized polymer was dissolved in acetonitrile (AN) with
0.1 M tetrabutylammonium perchlorate (TBAP) as an electrolyte. We used a plati-
num working electrode and a saturated Ag=AgNO3 reference electrode. Ferrocene
was used for potential calibration (all reported potentials are reference against
ferrocene=ferrocenium, FOC) and for reversibility criteria.
Results and Discussion
We performed the polymerization of DMPPAB by using transition metal catalysts.
We firstly test the polymerization of DMPPAB by W- and Mo-based catalysts,
which were found to be very effective for the polymerization of some monosubsti-
tuted acetylenes and the cyclopolymerization of various dipropargyl monomers
[1–3,28]. However, W-based catalysts such as WCl6 and WCl6-EtAlCl2 failed to
polymerize the present monomer. And also MoCl5 gave only a trace amount of
oligomeric product.
PdCl2 was found to effectively polymerize DMPPAB to give the corresponding
polymer in high yield (85%) although this monomer carry the bulky quaternary
ammonium salts. The polymer yields were slightly decreased when PtCl2 and RuCl3
were used as catalyst (62% and 75%, respectively). (NBD)PdCl2, which showed good
solubility in the polymerization solvent, polymerized DMPPAB to give the corre-
sponding polymer in 83% yield. The present polymerizations proceeded mostly in
mild manner.
The polymer structure was characterized by various instrumental methods such
as IR, NMR, UV-visible spectroscopies. The FT-IR spectrum of DMPPAB did not
show the acetylenic CꢁC bond stretching and acetylenic ꢁCꢂH bond stretching fre-
=
quencies of the monomer. Instead, the C C stretching frequency peak of conjugated
polymer backbone at 1580–1660 cmꢂ1 became more intense than that of the mono-
mer. The 1H-NMR spectrum of poly(DMPPAB) showed the phenyl protons and the
vinyl protons of the conjugated polymer backbone at 6.5–8.4 ppm. The characteristic
aliphatic methyl and methylene proton peaks was also observed at 2.4–5.0 ppm.
In the 13C-NMR spectrum of poly(DMPPAB), the acetylenic carbon peaks of
monomer at 72.68 and 82.72 ppm were disappeared and the aromatic and vinyl

Synthesis and Properties of an Ionic Polyacetylene
161=[437]
carbon peaks of polymer were observed at the region of 110–155 ppm. The methyl
and methylene carbon peaks were seen at 44.5 and 55.2 ppm, respectively. In
the UV-visible spectra, the absorptions at long wavelength (up to 650 nm) due
to the p!pꢃ interband transition of the conjugated polymer systems were observed.
From these spectral data, we concluded that the present polymer have the conju-
gated polymer backbone system with the designed substituents. The morphology
of poly(DMPPAB) powder sample was studied by X-ray diffraction analysis.
Because the peaks in the diffraction pattern were broad and the ratio of the
half-height width to diffraction angle (D2h=2h) is greater than 0.35, the present
poly(DMPPAB) was mostly amorphous [1,2]. The inherent viscosities of poly
(DMPPAB)s were in the range of 0.10–0.15 dL=g.
In order to characterize the electrochemical kinetic behavior and an electro-
chemically stable window, the cyclic voltammograms (CVs) of poly(DMPPAB)
Figure 2. Cyclic voltammograms of poly(DMPPAB) in 0.1 M TBAP=acetonitrile solution: (a)
consecutive scans under 100 mV=sec, (b) various scan rates of 30 mV=secꢄ150 mV=sec.

162=[438]
W.-C. Lee et al.
Figure 3. Plot of log ip,a vs log v for poly(DMPPAB) cyclic voltammograms.
including a consecutive scan and various scan rates (30 mV=sꢄ150 mV=s) were
recorded as shown in Figure 2. Typical CVs obtained at the scan rate of 100 mV=s
for poly(DMPPAB) solution are presented in Figure 2(a). We have observed that
the shape of CVs is almost unchanged, concluding that poly(DMPPAB) is fairly
stable without any severe degradation up to 30 cycles of the consecutive scan. In
Figure 2(b), as the speed of scan rate was increased, the peak potentials were gradu-
ally shifted to higher potentials and the current values were increased. Finally,
the oxidation of poly(DMPPAB) was occurred at 0.24 V (vs Ag=AgNO3), where
vinylene group of conjugated polymer backbone might be oxidized in the scan.
Poly(DMPPAB) also shows the irreversible reduction at ꢂ1.90 V. The redox current
value was gradually increased as the scan rate was increased. This result suggests that
the electrochemical process of poly(DMPPAB) is reproducible in the potential range
of ꢂ2.0ꢄþ1.5 V vs Ag=AgNO3 (Fig. 2).
It has been reported that the relationship between the redox peak current and
the scan rate can be expressed as a power law type as follows [29–31].
ip;a ¼ kvx
log ip;a ¼ log k þ x log v
ð1Þ
ð2Þ
where ip,a ¼ oxidation peak current density, v ¼ scan rate, k ¼ proportional constant,
and x ¼ exponent of scan rate.
Considering that electrode kinetics satisfy Eq (1), the electrochemical redox reac-
tion is controlled by either the electron transfer process, where x ¼ 1, or the reactant
diffusion process, where x ¼ 0.5. The relationship plot of the oxidation current den-
sity (log ip,a) as a function of the scan rate (log v) is shown in Figure 3. The oxidation
current of poly(DMPPAB) versus the scan rate is approximately linear relationship
in the range of 30 mV=secꢄ150 mV=sec and the exponent of scan rate, x value is
found to be 0.2976. This value means that the kinetics of the redox process is not
so active and is controlled by the diffusion process.

Synthesis and Properties of an Ionic Polyacetylene
163=[439]
Conclusions
A new conjugated polymer with bulky quaternary ammonium salts was synthesized
and characterized. The polymerization of DMPPAB catalyzed by transition metal
catalysts proceeded well to give high yield of polymer. The polymer structure was
characterized by various instrumental methods to have a conjugated polymer back-
bone system having the designed substituents. This polymer was mostly soluble in
organic solvents. The CVs of the polymer exhibited the irreversible electrochemical
behaviors between the doping and undoping peaks. It was found that the kinetics of
the redox process of poly(DMPPAB) might be controlled by the diffusion process
from the experiment of the oxidation current density of poly(DMPPAB) versus
the scan rate.
Acknowledgement
This work was supported by grant No. 41-10024463 from the Regional Technology
Innovation Program and the Regional Innovation Center for Automotive Compo-
nent Test (ACT-RIC of Kyungil University) from Regional Innovation Center
Program of the Ministry of Knowledge Economy (MKE). The authors thank Ms
S. E. Chai of Korea Basic Science Institute-Taegu Branch for the measurement of
the 500-MHz FT-NMR spectra of the polymers.
References
[1] Kang, K. L., Kim, S. H., Cho, H. N., Choi, K. Y., & Choi, S. K. (1993). Macromolecules,
26, 4539.
[2] Choi, S. K., Gal, Y. S., Jin, S. H., & Kim, H. K. (2000). Chem. Rev., 100, 1645.
[3] Lam, J. W. Y. & Tang, B. Z. (2005). Acc. Chem. Res., 38, 745.
[4] Masuda, T. (2007). J. Polym. Sci.: Part A: Polym. Chem., 45, 165.
[5] Potje-Kamloth, K. (2008). Chem. Rev., 108, 367.
[6] Joo, S. & Brown, R. B. (2008). Chem. Rev., 108, 638.
[7] Hatchett, D. W. & Josowicz, M. (2008). Chem. Rev., 108, 746.
[8] Grimsdale, A. C., Chan, K. L., Martin, R. E., Jokisz, P. G., & Holmes, A. B. (2009).
Chem. Rev., 109, 897.
[9] Kwak, G., Jin, S. H., Park, J. W., & Gal, Y. S. (2008). Macromol. Chem. Phys., 209, 1769.
[10] Gal, Y. S., Lee, W. C., Jin, S. H., Lim, K. T., Park, J. W., & Kim, S. Y. (2008). Mol.
Cryst. Liq. Cryst., 492, 229.
[11] Gal, Y. S., Jin, S. H., Hyun, A. R., Park, Y. I., Park, J. W., Lim, K. T., & Lee, W. C.
(2008). J. Ind. Eng. Chem., 14, 468.
[12] Lee, S. J., Park, J. S., Yoon, K. J., Kim, Y. I., Jin, S. H., Kang, S. K., Gal, Y. S., Kang,
S., Lee, J. Y., Kang, J. W., Lee, S. H., Park, H. D., & Kim, J. J. (2008). Adv. Funct.
Mater., 18, 3922.
[13] Gal, Y. S., Jin, S. H., Park, J. W., & Lim, K. T. (2009). J. Polym. Sci.: Part A: Polym.
Chem., 47, 6153.
[14] Yang, S. Y. & Rubner, M. F. (2002). J. Am. Chem. Soc., 124, 2100.
[15] Davidov, B. E., Krentsel, B. A., & Kchutareva, G. V. (1967). J. Polym. Sci.: Part C, 16,
1365.
[16] Kawasaki, M., Masuda, T., & Higashimura, T. (1983). Polymer J., 15, 767.
[17] Kim, S. H., Choi, S. J., Park, J. W., Cho, H. N., & Choi, S. K. (1994). Macromolecules,
27, 2339.
[18] Gal, Y. S., Lee, W. C., Jang, S. H., Lee, H. J., & Jin, S. H. (1997). Polymer (Korea),
21, 737.

164=[440]
W.-C. Lee et al.
[19] Vygodskii, Y. S., Shaplov, A. S., Lozinskaya, E. L., Vlasov, P. S., Malyshkina, I. A.,
Gavrilova, N. D., Kumar, P. S., & Buchmeiser, N. R. (2008). Macromolecules, 41, 1919.
[20] Gal, Y. S., Jin, S. H., & Choi, S. K. (2004). J. Mol. Cat. A-Chem., 213, 115.
[21] Gal, Y. S., Jin, S. H., & Kim, S. H. (2006). J. Ind. Eng. Chem., 12, 235.
[22] Gal, Y. S., Jin, S. H., & Park, J. W. (2007). J. Polym. Sci.: Part A: Polym. Chem., 45,
5679.
[23] Gal, Y. S., Jin, S. H., Karim, M. A., & Cho, Y. R. (2009). Mol. Cryst. Liq. Cryst., 498,
165.
[24] Gal, Y. S. (1994). J. Chem. Soc., Chem. Commun., 327.
[25] Gal, Y. S., Jung, B., Lee, W. C., & Choi, S. K. (1995). Synth. Met., 69, 549.
[26] Subramanyam, S. & Blumstein, A. (1992). Macromolecules, 25, 4058.
[27] Balogh, L., Samuelson, L., Alva, K. S., & Blumstein, A. (1998). J. Polym. Sci.: Part A:
Polym. Chem., 36, 703.
[28] Gal, Y. S., Jin, S. H., Park, J. W., Lee, W. C., Lee, H. S., & Kim, S. Y. (2001). J. Polym.
Sci.: Part A: Polym. Chem., 39, 4101.
[29] Bard, A. J. & Faulker, L. R. (1980). Electrochemical Methods, Wiley: New York,
Chapters 3, 6 and 10.
[30] Ko, J. M., Rhee, H. W., Park, S. M., & Kim, C. Y. (1990). J. Electrochem. Soc., 137, 905.
[31] Kim, Y. E., Kwon, Y. S., Lee, K. S., Park, J. W., Seo, H. J., & Kim, T. W. (2004). Mol.
Cryst. Liq. Cryst., 424, 153.

Copyright of Molecular Crystals & Liquid Crystals is the property of Taylor & Francis Ltd and its content may
not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written
permission. However, users may print, download, or email articles for individual use.