Advances in Ma terials Physics and Che mist ry, 2012, 2, 38-39
doi:10.4236/ampc.2012.24B011 Published Online December 2012 (htt p://www.SciRP.org/journal/ampc)
Synthesis and Characterization of
Poly(1-methoxy-4-octyloxy)-Para-Phenylene Vinylen for
Light-Emitting Diodes Application
Piched Anuragudom
Department of Chemistry, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng, Nakhon Pathom, Thailand
Received 2012
ABSTRACT
In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthes ized and ch a-
racterized . M O-p-PPV was synth esi zed acco rd in g to Gilch po lymeri zatio n mechanis m by using 4-methoxyphenol as starting material
in the p resence of potassi um tert-butoxide (1M in THF). The product was further purified by multiple precipitations in different sol-
vents such as methanol, tetrahydrofuran, isopropyl alcohol and hexane. The final product was dried to afford MO-p-PPV as a red
solid. The resulting polymer was completely soluble in common organic solvents. The structure of monomer and optical properties of
polymer were chara cterized by p roton nuclear magneti c resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and fluorescence
spectroscopy. The UV-vis spectrum showed absorption maxima for MO-p-PPV at 491 nm. Si milarly, flu orescen ce spectru m sho wed
λma x e mission at 540 nm.
Keywords: Component; Po ly( 1-Methoxy-4-Oc tylox y)-Para-Phenyl ene V in ylen; Gilch Polymerization; Light-Emitting Diodes
1. Introduction
During the past decade, an explosive growth of activity in the
area of organic electroluminescence has occurred in both acade-
mia and industry [1]. As the potential base material in organic
light-emitting diodes (OLEDs), conjugated polymers have been
widely explored. For example, since the discovery of electro-
luminescence in poly(p-phenylene vinylene) (PPV) [2,3], a
wide variety of conjugated and semi-conjugated polymers have
been used as the active emissive layer in OLED devices [4-7].
Polymer light-emitting diodes (PLEDs) are promising devices,
especially for next generation active matrix displays. Solution
deposition techniques, homogeneous large area thin films, re-
duced manufacturing process complexity, low-cost, high lumi-
nescence efficiency, large spectral range, and relatively simple
device stru ctures are so me of the main r easons for an increased
interest in polymer materials for LED’s [ ]. M. T. Bernius, M.
Inbasekaran, J. O'Brien, and W. Wu, Adv. Mater., 12, 1737
(2000).
We report here the preparation of poly(1-methoxy-4-octy-
lox y) -para-phenylene vinylene (MO-p-PPV) for light emitting
diodes application by using Gilch polymerization route. A typ-
ical procedure for the synthesis was described in the Experi-
mental sect ion.
2. Experiment
2.1. Materials
4-methoxyphenol, 1-bromooctane, Sodium bromide, parafor-
maldehyde, potassium tert-butoxide (1 M solution in THF),
KOH, glacial acetic acid, conc. H2SO4 were purchased from
Aldrich Chemical Co. and used without further purification
unless otherwise noted. THF was dried and purified by frac-
tional distillation over sodium/benzophenone and handled in a
moisture-fr ee atmosphere.
2.2. Measurements
1H and 13C NMR spectra were recorded using a Bruker avance
400 MHz, and chemical shifts were recorded in ppm. The data
were processed using NUTS NMR Utility Transform Software
(Acron NMR). The UV-vis spectra were recorded on a Perkin
Elmer Lambda 19 UV-VIS -NIR spectrophotometer with base-
line corrections and normalizations carried out using WinLab
software. Fluorescence spectra were collected on a Perkin El-
mer Luminescence S pectro meter LB 50.
Methoxy-4-octyloxy benzene (1)
4-methoxyphenol (10.0 g, 0.083 mol) was dissolved by 100
ml ethanol, 6.0 g (0.12 mol) of KOH and octyl bromide (22.4 g,
0.12 mol) were added and strired at 70 oC for 24 h. After the
reaction , precip itat e was collect ed b y filtrati on and wash ed with
ethanol. White crystalline 1 (67% yield) was obtained.
1,4-Bis(bromomethyl)-methoxy-4-octyloxy benzene (2)
Methoxy-4-octyloxy benzene (0.169 mol), Sodium bromide
(0.097 mol), paraformaldehyde (0.166 mol) were dissolved in
24 ml of glacial acetic acid. 50% conc. H2SO4 in glacial acetic
acid was added and the reaction was heated at 70oC for 24 h.
Then saturated NaHCO3 was added until the red color disap-
peared. The mixture was extracted three times with dichloro-
methane. The organic extracts were combined, washed with
brine, and dried with magnesium sulfate. Upon filtering the
solution and evaporating the solvent, a white solid was obtained,
which was recrystallized in hexane and washed with cool me-

P. ANU RAGUDOM
39
thanol to give white crystals of pure 2 (60%).
Poly(1-met hoxy-4-octyloxy)-par a-phen ylene vinylene
(MO-p-PPV)
of 1,4-Bis(bromomethyl)-methoxy-4-octyloxy benzene (0.00238
mol) was dissolved in 25 mL of anhydrous THF under nitrogen,
and a 10 mL of THF solution of potassium tert-butoxide was
added. The mixture was stirred overnight at room temperature
under nitrogen. The resulting polymer was precipitated into 100
mL of methanol, and the mixture was centrifuged. The super-
natant was decanted, and the residue was re-dissolved in a
minimum amount of THF. The crude polymer was then succes-
sively re-precipitated into methanol and propanol. Red crystal-
line (55%) was obtained
3. Results and Discussion
Figures 1 and 2 shows the UV-Vis absorption and fluorescen ce
(FL) spectra of the MO-p-PPV synthesized via Gilch polyme-
rization. The Gilch polymerization affords MO-p-PPV having a
broad absorption band with λmax = 491 nm. This band can be
attributed to π-π* transitions of the conjugated backbones. Flu-
orescence spectra obtained upon excitation at 497 nm. The
Gilch polymerization affords MO-p-PPV having a strong emis-
sion band at 540 nm.
4. Conclusions
Po ly (1 -methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-
PPV) was successfully synthesized by Gilch polymerization.
UV-Vis absorption spectrum in THF showed the broad absorp-
tion band with λmax = 491 nm. The PFV exhibited a greenish
fluorescence at λmax emission = 540 nm.
(1) (2)
Scheme 1. Synthesis of poly(1-met hoxy-4-octyloxy)-para-phenylene
vinylene (MO-p-PPV).
360 390 420 450 480 510 540 570600 630 660 690
Intensity (a.u.)
W avelength (nm)
Figure 1. UV-Vis spectrum of poly(1-met hox y-4-octyloxy)-para-
phenylene vinylene (MO-p-PPV) (1.0 x 10-4 M) prepared by Gilch
polymerization in THF at room temperature.
510 540 570 600 630 660 690
Intensity (a.u.)
W avelength (nm)
Figure 2. Fluorescence spectrum of Poly (1-me th oxy-4-octyloxy)-
para-phenylene vinylene (MO-p-PPV) (1.0 x 10-5 M) Gilch polyme-
rization in THF at room temperature (excitation 497 nm).
5. Acknowledgements
I would like to thank Prof. Dr. Thomas Randall Lee at Houston
University for instruments.
REFERENCES
[1] Brown, A.R.; Bradley, D.D.C.; Burroughes, J.H.; Friend, R.H.;
Greenham, N.C.; Burn, P.L.; Holmes, A.B.; Kraft, A. Appl. Phys.
Lett. 1992,
[2] Karg, S.; Riess, W.; Dyakonov, V.; Schwoerer, M. Synth. Met.
1993, 54, 427.
[3] S.L. Issler, C.C. Torardi, J. Alloy. Compd. vol. vol. 229, 1995,
pp. 54.
[4] I. Kandarakis, D. Cavouras, Appl. Radiat. Isot. vol. 54, 2001, pp.
821.