Synthesis and photolithographic property of conjugated polymers with polyazomethine structure

Article abstract of DOI:10.1080/15421400903240803

Two different polyazomethine-type conjugated polymers, poly(phenoxiazine-3, 3′-dihydroxybensidine)(PZ-DHB) and poly(phenoxiazine-2,4-diamino-6- hydroxypyrimidine)(PZ-DHP) containing phenothiazine moiety and azomethine linkage in the main chain were synthe

Full text of DOI:10.1080/15421400903240803

This article was downloaded by: [Northeastern University]
On: 24 November 2014, At: 10:18
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954
Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,
UK
Molecular Crystals and Liquid
Crystals
Publication details, including instructions for
authors and subscription information:
http://www.tandfonline.com/loi/gmcl20
Synthesis and
Photolithographic Property
of Conjugated Polymers with
Polyazomethine Structure
Sang Chul Ryu a , Young Chul Jeong b & Lee Soon
Park c d
a LG Display Co. LTD. , Gumi-si, Gyungsangbuk-do,
Korea
b Exax Co. Led. , Kongdan-dong, Gumi-si
Gyungsangbuk-do, Korea
c Department of Polymer Science , Kyungpook
National University , Daegu, Korea
d Advanced Display Manufacturing Research Center ,
Kyungpook National University , Daegu, Korea
Published online: 10 Nov 2009.
To cite this article: Sang Chul Ryu , Young Chul Jeong & Lee Soon Park
(2009) Synthesis and Photolithographic Property of Conjugated Polymers with
Polyazomethine Structure, Molecular Crystals and Liquid Crystals, 514:1, 235/
[565]-248/[578], DOI: 10.1080/15421400903240803
To link to this article: http://dx.doi.org/10.1080/15421400903240803
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the
information (the “Content”) contained in the publications on our platform.
However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness,

or suitability for any purpose of the Content. Any opinions and views
expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the
Content should not be relied upon and should be independently verified with
primary sources of information. Taylor and Francis shall not be liable for any
losses, actions, claims, proceedings, demands, costs, expenses, damages,
and other liabilities whatsoever or howsoever caused arising directly or
indirectly in connection with, in relation to or arising out of the use of the
Content.
This article may be used for research, teaching, and private study purposes.
Any substantial or systematic reproduction, redistribution, reselling, loan,
sub-licensing, systematic supply, or distribution in any form to anyone is
expressly forbidden. Terms & Conditions of access and use can be found at
http://www.tandfonline.com/page/terms-and-conditions

Mol. Cryst. Liq. Cryst., Vol. 514, pp. 235=[565]–248=[578], 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 1542-1406 print=1563-5287 online
DOI: 10.1080/15421400903240803
Synthesis and Photolithographic Property
of Conjugated Polymers with Polyazomethine
Structure
Sang Chul Ryu1, Young Chul Jeong2, and Lee Soon Park3,4
1LG Display Co. LTD., Gumi-si, Gyungsangbuk-do, Korea
2Exax Co. Led., Kongdan-dong, Gumi-si Gyungsangbuk-do, Korea
3Department of Polymer Science, Kyungpook National University,
Daegu, Korea
4Advanced Display Manufacturing Research Center, Kyungpook
National University, Daegu, Korea
Two different polyazomethine-type conjugated polymers, poly(phenoxiazine-3,
30-dihydroxybensidine)(PZ-DHB) and poly(phenoxiazine-2,4-diamino-6-hydroxy-
pyrimidine)(PZ-DHP) containing phenothiazine moiety and azomethine linkage
in the main chain were synthesized by Schiff-base polycondensation reactions.
The polymer poly(PZ-DHB) was converted to the photosensitive type, through
Mitsunobu reaction by incorporation of a photocrosslinkable group, hydroxy-
hexyloxystyryl-2-pyridine(2-HHSP) into the polymer side chains. The photosensi-
tive conjugated polymer, poly(PZ-DHB)-PS, exhibited both strong fluorescence
emission at 555 nm and good patterning property in the standard photolitho-
graphic processes.
Keywords: conjugated polymers; photolithography; polyazomethine
INTRODUCTION
Conjugated polymers have attracted much interest from researchers
for their potential applications to the large area organic light emitting
diodes (OLEDs) since the first polymer light-emitting diode (PLED)
using poly(p-phenylenevinylene) (PPV) was reported by Friend et al.
in 1990 [1–3]. Conjugated polymers can be easily converted to thin film
This work was supported by the Advanced Display Manufacturing Research Center
(ADMRC) program of the Ministry of Knowledge Economics, Republic.
Address correspondence to Prof. Lee Soon Park, Department of Polymer Science,
Kyungpook National University, Sangyuk-dong, Buk-gu, Daegu 702-701, Korea
(ROK). E-mail: lspark@knu.ac.kr
235=[565]

236=[566]
S. C. Ryu et al.
by spin-coating process and the resulting PLED devices have merits
of low threshold voltages and high external quantum efficiency. The
PLEDs employing conjugated polymers, however, need to increase
luminance efficiency and color purity compared with OLEDs contain-
ing small molecular light emitting materials.
Conjugated polymers such as PPV and polyfluorenes have been
widely used in the fabrication of PLEDs [4–7]. Conjugated polymers
containing heterocyclic structures have also been studied. For exam-
ple polyazomethines with cyano groups were reported to have
high luminance efficiency, thermal stability and good solubility to
common organic solvents [8–11]. Weaver et al. reported that poly(1,4-
phenylenemethylidynenitrilo-1,4-phenylenenitrinilomethylidyne) con-
taining azomethine unit in the main chain exhibited similar
performance as PPV in PLEDs in which the emitting layer was formed
by chemical vapor deposition (CVD) method [10]. Fischer et al. also
formed oligo-azomethine thin film utilizing aromatic diamine and
dialdehyde monomers under high vacuum and found that the
materials had good electron transfer properties [11]. In these works
polyazomethine thin films were formed by thermal evaporation under
high vacuum conditions.
In this work we synthesized heterocyclic conjugated polymers with
azomethine units in the main chain and a photosensitive version of
azomethine polymer. These polymers were investigated for their
electroluminescent property and for the photolithographic process
properties.
EXPERIMENTAL
1. Materials
Phenothiazine, 2-ethylhexyl bromide, phosphorus oxychloride,
p-hydroxybenzaldehyde, 6-bromo-1-hexanol, sodium acetate, 2-pico-
line and 2,4-diamino-6-hydroxypyrimidine were purchased from
Aldrich Chemical Co. and used as received. 3,30-Dihydroxybenzidine,
triphenylphosphine(PPh3) and diethylazodicarboxylate (DEAD) were
purchased from TCI and used without further purification. Dimethyl-
sulfoxide, dioxane, dimethyl formamide, 1,2-dichloroethane and other
solvents were distilled before use.
2. Synthesis of Electroluminescent (EL) Polymers
Synthesis of intermediates and conjugated polymers with electrolumi-
nescent (EL) property are shown in Scheme 1.

Synthesis and Photolithographic Property of Conjugated Polymers 237/[567]
SCHEME 1 Synthetic procedure and structures of poly(PZ-DHP) and
poly(PZ-DHB).
2.1. Synthesis of poly(PZ-DHB)
2.1.1. N-(2-Ethylhexyl)phenothiazine(EHPZ). First dimethylsulfox-
ide (DMSO) (60 mL) and sodium hydroxide (7.2 g, 0.18 mol) were
charged in a three-necked flask and stirred for 30 min while flushing
with nitrogen gas. Phenothiazine (6 g, 0.03 mol) and 2-ethylhexyl-
bromide (5.8 g, 0.03 mol) were added to this suspension solution and
the mixture was reacted for 24 hr at room temperature [12,13]. After
reaction DMSO was removed by using rotary evaporator. Then
acetone was added into the reaction mixture and the resulting insolu-
ble sodium hydroxide was removed by filteration. The product solution

238/[568]
S. C. Ryu et al.
was purified by extraction with the water and dichloromethane
mixture solvent. The crude product obtained form the dichloro-
methane part was purified by column chromatography by using and
n-hexane:ethyl acetate (9:1 v=v) as eluent, and then dried to give a
transparent liquid product, N-(2-ethylhexyl)phenothiazine(EHPZ).
Yield: 73%, 1H-NMR(CDCl3), d: 6.87, 7.12 (m, 8H, Ar-H), 3.70 (m, 2H,
>NꢀCH2ꢀ), 1.93 (t, 1H, >CHꢀ), 1.22–1.44 (m, 9H, ꢀCH2ꢀ), 0.83–0.87
(m, 6H, ꢀCH3), IR(KBr), cmꢀ1: 3064 (Ar CH), 2926 (aliphatic CH), 2857
=
(>NꢀCH2ꢀ), 1593, 1485 (Ar C C).
2.1.2. N-(2-Ethylhexyl)-3,6-diformylphenothiazine(DFPZ). Introduction
of aldehyde groups to the EPHZ intermediate was achieved by using
Vilsmeier-Haack reaction [10,11]. First EHPZ (12.36 g, 0.04 mol)
was dissolved in 1,2-dichlororoethane (30 mL) solvent followed by
addition of dimethylformamide (58.5 g, 0.8 mol) reagent. After the
solution was cooled to 0ꢁC phosphorus oxychloride (122.7 g,
0.8 mol) was added dropwise for 30 min, and then the mixture was
stirred for 72 hr at the refluxing temperature. The mixture was then
cooled to 25ꢁC and sodium acetate aqueous solution (33 wt%,
27.34 g) was added. After removal of solvents by evaporation, acet-
one was added and the insoluble salt was removed by filteration.
The product solution was purified by extraction with water and
dichloromethane mixture solvent. The crude product obtained from
the dichloromethane part was purified by column chromatography
using n-hexane:ethyl acetate (3:1 v=v) as eluent, and then dried to
give the solid product, N-(2-ethylhexyl)-3,6-diformylphenothiazine
(DFPZ).
1
Yield: 40%, H-NMR(CDCl3), d: 9.73 (m, 2 H, aldehydic hydrogen),
6.88, 7.56 (m, 6 H, Ar H), 3.73 (t, 2 H, >NꢀCH2ꢀ), 1.17–1.85 (m, 9 H,
ꢀCH2ꢀ, >CHꢀ), 0.76–0.82 (m, 6 H, ꢀCH3), IR(KBr), cmꢀ1: 3048 (Ar
CH; weak signal), 2927 (aliphatic CH), 2857 (>NꢀCH2ꢀ), 2724
=
=
(aldehydic hydrogen), 1688 (>C O), 1600, 1465 (Ar C C).
2.1.3. Synthesis of poly(PZ-DHB). The DFPZ (3.67 g, 0.01 mol)
monomer synthesized above and another monomer 3,30-dihydroxybenzidine
(2.16 g, 0.01 mol) were dissolved in THF (60 mL) solvent and the
mixture solution was refluxed for 24 hr to give a heterocyclic EL
polymer with azomethine units, poly(PZ-DHB). After polymerization
the product polymer was precipitated with n-hexane as non-solvent.
The polymer was further purified by reprecipitation and then dried
in the vacuum oven for 24 hr at 30ꢁC to give purified product,
poly(PZ-DHB).
Yield: 68%, IR(KBr), cmꢀ1: 3027 (Ar CH), 2924 (aliphatic CH), 2857
=
=
(>NꢀCH2ꢀ), 1620, 1467 (ꢀN Cꢀ), 1580, 1467 (Ar C C).

Synthesis and Photolithographic Property of Conjugated Polymers 239/[569]
2.2. Synthesis of Poly(PZ-DHP)
The DFPZ (3.67 g, 0.01 mol) monomer and 2,4-diamino-6-hydroxy-
pyrimidine (1.26 g, 0.01 mol) was dissolved in DMSO (60 mL) solvent
and the mixture solution was refluxed for 24 hr to give another EL
polymer, poly(PZ-DHP). The product polymer was purified by repreci-
pitation using n-hexane as non-solvent and then dried under vacuum.
Yield: 78%, IR(KBr), cmꢀ1: 3018 (Ar CH), 2925 (aliphatic CH), 2856
=
=
(>NꢀCH2ꢀ), 1625, 1481 (ꢀN Cꢀ), 1579, 1481 (Ar C C).
2.3. Synthesis of Photosensitive EL Polymer,
poly(PZ-DHB)-PS
A photosensitive EL polymer, poly(PZ-DHB)-PS was synthesized by
introduction of photocrosslinkable units in the side chain as shown in
Scheme 2.
2.3.1. Synthesis of hydroxystyryl-2-pyridine (2-HSP). 2-Picoline
(12 g, 0.13 mol), p-hydroxybenzaldehyde (20.9 g, 0.17 mol) and acetic
anhydride (26.3 g, 0.26 mol) were refluxed for 24 hr in a three neck
flask equipped a cooling condenser under nitrogen atmosphere. After
reaction the intermediate product (2-ASP) was precipitated in a
ice-water bath and filtered. Recrystallization of 2-ASP in ethanol gave
pure product in 62.5% yield. The intermediate (2-ASP) was added to a
mixture solution of 0.5 N KOH=EtOH in a three neck flask and then
refluxed for 1 hr. The hydrolyzed product was neutralized by adding
4 ml of 1 N HCl solution followed by filtration. Recrystallization in
ethanol gave hydroxystyryl-2-pyridine (2-HSP) in 72.3% yield.
2.3.2. Hydroxyhexyloxystyryl-2-pyridine (2-HHSP). The inter-
mediate 2-HSP (6 g, 0.03 mol) was dissolved in 500 ml acetone in a
three neck flask and then K2CO3 (12.4 g, 0.09 mol) was added and
the mixture was refluxed for 1 hr. Into the mixture solution 6-bromo-1-
hexanol was slowly added and the whole mixture was refluxed for
24 hr. After reaction KBr byproduct was removed by filteration and
the filterate was passed through a silica gel column with acetone as
solvent. The product solution was concentrated by using rotary
evaporator and then extracted with n-hexane below 4ꢁC. The
extracted product was recrystallized in the acetone=ethanol (v=v ¼ 1.5)
mixture solvent to give 2-HHSP in 67.3% yield.
2.3.3. Synthesis of photosensitive EL polymer, poly(PZ-DHB)-
PS. The substrate polymer, poly(PZ-DHB) (1 eq.), the photosensitive
compound, 2-HHSP (1.5 eq.) and triphenyl phosphine (PPh3) (1.5
eq.) were dissolved in THF solvent in a three neck flask and then
diethyl azodicarboxylate(DEAD) (1.5 eq.) was added dropwise over

240/[570]
S. C. Ryu et al.
SCHEME 2 Synthetic procedure and the structure of photosensitive polymer,
poly[(PZ-DHB)-PS].
1 hr and the whole reaction mixture was reacted for 72 h at room tem-
perature. After reaction THF was removed by rotary evaporator and
the product was precipitated with methanol as non-solvent. The

Synthesis and Photolithographic Property of Conjugated Polymers 241/[571]
product polymer was purified by reprecipitation in methanol followed
by filteration and drying in vauum oven for 24 hr at 30ꢁC to give a
photosensitive EL polymer, poly(PZ-DHB)-PS.
Yield: 62%, IR(KBr), cmꢀ1: 3018 (Ar CH), 2900 (aliphatic CH), 2856
=
=
=
(>NꢀCH2ꢀ), 1635 (ꢀC Cꢀ), 1620, 1481 (ꢀN Cꢀ), 1579, 1481 (Ar C C).
3. Measurement
Infrared spectra were obtained with a JASCO FT-IR 620 spectro-
1
meter. H-NMR spectra were recorded on a Bruker 400 NMR spectro-
meter with chloroform-d(CDCl3) as solvent and tetramethylsilane
(TMS) as internal reference. UV=visible and fluorescence spectra of
synthesized products were obtained with a Simadzu UV-5100 spectro-
photometer and JASCO FP-6500 fluorescence spectrometer, respec-
tively. Thermal stability of the compounds was evaluated by using a
Seiko SSC5200 H Disk Station (DSC220C) under dry nitrogen at a
heating rate of 20ꢁC=min. The average molecular weights (Mw and
Mn) of the polymers were measured with a gel permeation chromato-
graph (Waters, alliance 2000, eluent THF, polystyrene universal
calibration) at room temperature.
RESULTS AND DISCUSSION
1. Synthesis and Characterization
In the synthesis of heterocyclic conjugated polymers, poly
(phenoxiazine-3,30-dihydroxybensidine)(PZ-DHB) and poly(phenoxiazine-
2,4-diamino-6-hydroxypyrimidine)(PZ-DHP), it was found that the
Schiff-base reaction [14,15] was useful to obtain polycondensation pro-
duct with relatively high molecular weights and yield. As shown in
Table 1 the yields of poly(PZ-DHB) and poly(PZ-DHP) were 68% and
78%, respectively. The thermal stability was also high as confirmed
by initial thermal decomposition temperatures (Tid) of 320ꢁC and
230ꢁC, respectively. The lower thermal decomposition temperature
of poly(PZ-DHP) than poly(PZ-DHB) seemed to be due to rather low
TABLE 1 Characterization Data of Poly(PZ-DHB) and
Poly(PZ-DHP)
Polymer
Yield (%)
Mw(ꢂ10ꢀ4
)
Mn(ꢂ10ꢀ4
)
Tid
Poly(PZ-DHB)
Poly(PZ-DHP)
68
78
1.14
0.96
0.77
0.65
320
230

242/[572]
S. C. Ryu et al.
molecular weight (Mw) of the polymer. The Mw of poly(PZ-DHB) was
determined to be 1.12 ꢂ 104 and Mw=Mn value was 1.45, however,
Mw of poly(PZ-DHP) could not be measured by GPC due to lack of solu-
bility in common solvents. The poor solubility but higher yield of
poly(PZ-DHP) than poly(PZ-DHB) suggested that poly(PZ-DHP) chain
was much stiffer than poly(PZ-DHB) which has biphenyl joint unit in
the main chain, thus leading to premature precipitation during the
polymerization reaction.
The introduction of photocrosslinkable moiety (2-HHSP) to poly(PZ-
DHB) was achieved through Mitsunobu reaction by using triphenyl
phosphine and diethylazodicarboxylated (DEAD) reagents [16,17].
The photocrosslinkable conjugated polymer, poly[(PZ-DHB)-PS] was
obtained in 65% yield and the 2-HHSP photocrosslinꢀk1able unit was
=
confirmed by the characteristic C C bond at 1635 cm as shown in
Figure 1.
2. Optical and Photocrosslinking Properties
UV-visible and PL spectra of poly(PZ-DHB) and poly(PZ-DHP) in
5 ꢂ 10ꢀ5 M solution of THF are shown in Figure 2. The UV absorption
of poly(PZ-DHB) exhibited two peaks at 300 and 430 nm corresponding
FIGURE 1 FT-IR spectrum of photosensitive polymer, poly[(PZ-DHB)-PS].

Synthesis and Photolithographic Property of Conjugated Polymers 243/[573]
FIGURE 2 UV absorption (a) and fluorescence spectra (b) of poly(PZ-DHP)
and poly(PZ-DHB) (kBexB ¼ 400 nm, c ¼ N5.0 ꢂ 10Pꢀ5 M in THF).
to p-pꢃ transition of azomethine and azo group, respectively. The UV
absorption of azomethine in poly(PZ-DHP) was shifted to longer
wavelength (362 nm) compared with that of poly(PZ-DHB) due to the

244/[574]
S. C. Ryu et al.
non-bonding electrons of nitrogen atom in the pyrimidine ring. The
UV absorption poly[(PZ-DHB)-PS] exhibited similar peaks except a
peak at 330 nm due to the strylylpyridyl group.
When three polymer, poly(PZ-DHP), poly(PZ-DHB) and poly[(PZ-
DHB)-PS] were excited at the UV maximum absorption (kmax,abs), their
fluorescence spectra showed the maximum emission (kmax,em) at 462,
560 and 555 nm, respectively. The conjugated polymer poly(PZ-DHP)
with azomethine unit exhibited strong blue emission, while
poly(PZ-DHB) and poly[(PZ-DHB)-PS] emitted greenish yellow color
due to increased conjugation compared to poly(PZ-DHP).
3. Photosensitive Properties of Poly[(PZ-DHB)-PS]
Figure 3 shows the UV adsorption spectra of poly(PZ-DHB)-PS in THF
solution (5 ꢂ 10ꢀ5 M) and in the film state under varying UV exposure
dose. The UV spectra both in solution and film state exhibited that UV
absorption at 330 nm decreased with increasing UV dose and became
constant under 1.3 J=cm2.
These results would be explained by the [2 þ 2] photocycloaddition
reaction of styrylpyridyl groups present in the side chains of
poly(PE-DHB)-PS [18,19].
The change of normarlized UV absoptions of poly(PZ-DHB)-PS
both in solution and film state at 330 nm are shown in Figure 4 accord-
ing to the UV exposure dose. It was noted from Figure 4 that the UV
absorption decreased fast in solution but in film state decreased slowly
with the UV exposure dose, which could be explained by the restricted
movement of the pendant styrylpyridyl groups in the film state.
The FT-IR spectra of poly(PZ-DHB)-PS films before (a) and after (b)
UV exposure are shown in Figure 5. The photo-activity of poly
(PZ-DHB)-PS was ꢀd1etermined to be 65% by comparing the absorbance
of C N(at 1380 cm ) and C C(at 1635 cmꢀ1)in film state according to
equation(1).
=
=
Photo-reactivityð%Þ ¼ 100 ꢀ ½ðI
=IðCNÞÞ=ðIOðC¼CÞ=IOðCNÞÞ ð1Þ
ðC¼CÞ
=
where, IO(C¼C) ¼ Area of C C peak before UV exposure, IO(CN) ¼ Area of
=
ꢀCN peak before UV exposure, I(C¼C) ¼ Area of C C peak before UV
exposure (2.0 J=cm2), I(CN) ¼ Area of ꢀCN peak before UV exposure
(2.0 J=cm2).
The patterning property of the conjugated polymer, poly(PZ-DHB)-
PS, was checked by the following photolithographic process. The
poly(PZ-DHB)-PS solution in THF (2 wt%) was spin-coated on a

Synthesis and Photolithographic Property of Conjugated Polymers 245/[575]
FIGURE 3 UV spectra of poly(PZ-DHB)-PS in THF solution (a) and in
film state (b) when exposed to unpolarized UV light at varying dose.
cleaned ITO-glass at a series of speed, 500 rpm for 5 sec and 2500 rpm
for 25 sec. The cast film was dried on an IR oven at 110ꢁC for 1 hr. The
resulting thin film was exposured to UV light to the dose of

246/[576]
S. C. Ryu et al.
FIGURE 4 The change of normalized absorbance of poly(PZ-DHB)-PS in THF
solution and in film state according to the UV dose.
FIGURE 5 FT-IR spectra of poly(PZ-DHB)-PS films before (a) and after
(b) irradiation of unpolarized UV light.

Synthesis and Photolithographic Property of Conjugated Polymers 247/[577]
FIGURE 6 The SEM image of poly(PZ-DHB)-PS thin film after photolitho-
graphic process.
2000 mJ=cm2 through a photomask in a contact mode. The poly
(PZ-DHB)-PS film gave a fine pattern with line width (80 mm), space
(445 mm) and thickness (2 mm) as shown in Figure 6.
The photosensitivity of conjugated polymer is a desirable property
for the fabrication of polymer light emitting diode (PLED). The per-
formance of poly(PZ-DHB)-PS in the PLED devices will be reported
else where.
CONCLUSION
Conjugated polymers containing phenothiazine moiety and azo-
methine linkage in the main chain were synthesized by Schiff-base
polycondensation. The photosensitive version of the polymer, poly
(PZ-DHB)-PS, was also synthesized by introduction of styrylpyridyl
group in the side chins.
The photosensitive polymer exhibited good solubility in common
organic solvents and strong PL emission at 555 nm. The photosensitive
polymer was also found to have good patterning property in the stan-
dard photolithographic process.

248/[578]
S. C. Ryu et al.
REFERENCES
[1] Burroughes, J. H., Bradley, D. D. C., Brown, A. R., Narks, R. N., Mackay, K.,
Friend, R. H., Burns, P. L., & Holnes, A. B. (1990). Nature, 347, 539.
[2] Strukjelj, M., Jordan, R., & Dodabalapur, A. (1996). J. Am. Chem. Soc., 118, 1213.
[3] Tang, R. P., Tan, Z. A., Cheng, C. X., Li, Y. F., & Xi, F. (2005). Polymer, 46, 5341.
[4] Greenham, N. C., Moratti, S. C., Bradley, D. D. C., Friend, R. H., & Holmes, A. B.
(1993). Nature, 365, 628.
[5] Saadeh, H., Goodson III, T., & Yu, L. (1997). Macromolecules, 30, 4608.
[6] Doi, S., Kuwabara, M., Noguchi, T., & Ohnishi, T. (1993). Synth. Met., 55, 4174.
[7] Jin, J.-I., Lee, Y.-H., Park, C.-K., & Nam, B.-K. (1994). Macromolecules, 27, 5239.
[8] D’ Alelio, G. F., Crivello, J. V., Schoenig, R. K., & Hummer, T. F. (1967). J. Macro-
mol. Sci. Chem. A, 1, 1161.
[9] Wang, C., Shieh, S., LeGoff, E., & Kanatzidis, M. G. (1996). Macromolecules, 29,
3147.
[10] Weaver, M. S. & Bradley, D. D. C. (1996). Synth. Met., 83, 61.
[11] Fischer, W., Stelzer, F., Meghdadi, F., & Leising, G. (1996). Synth. Met., 76, 201.
[12] Paquette, L. A. (1995). Encyclopedia of Reagent for Organic Synthesis, John Wiley
& Sons: New York, Vol. 6, 4133.
[13] Wei, Y., Yang, Y., & Yeh, J.-M. (1996). Chem. Mater., 8, 2659.
[14] Wang, C., Shieh, S., LeGoff, E., & Kanatzidis, M. G. (1996). Macromolecules, 29,
3147.
[15] Destri, S., Pasini, M., Pelissi, C., Porzio, W., Predieri, G., & Vignali, C. (1999).
Macromolecules, 32, 353.
[16] Chen, T.-A., Jen, A. K. Y., & Cai, Y. (1996). Macromolecules, 29, 535–539.
[17] Mitsunobu, O. 1981. Synthesis, Jan, 1.
[18] Yamaki, S., Nakagawa, M., Morino, S., & Ichimura, K. (2001). Macromol. Chem.
Phys. 202, 325–334.
[19] Yamaki, S., Nakagawa, M., Morino, S., & Ichimura, K. (2001). Macromol Chem.
Phys., 202, 354–361.