Novel high-Tg poly(amine-imide)s bearing pendent N-phenylcarbazole units: Synthesis and photophysical, electrochemical and electrochromic properties

Article abstract of DOI:10.1039/b602133f

A new carbazole-derived, triphenylamine-containing aromatic diamine monomer, 4,4′-diamino-4″-N-carbazolyltriphenylamine, was successfully synthesized by the caesium fluoride-mediated condensation of N-(4-aminophenyl)carbazole with 4-fluoronitrobenzene, followed by palladium-catalyzed hydrazine reduction. A series of novel poly(amine-imide)s 6a-6g with pendent N-phenylcarbazole units having inherent viscosities of 0.17-0.56 dL g^-1 were prepared from the newly synthesized diamine monomer and seven commercially available tetracarboxylic dianhydrides via a conventional two-step procedure that included a ring-opening polyaddition to give polyamic acids, followed by chemical or thermal cyclodehydration. The polymers of the series were amorphous and most of them could afford flexible, transparent, and tough films with good mechanical properties. All the poly(amine-imide)s had useful levels of thermal stability associated with high glass-transition temperatures (303-371 °C), 10% weight-loss temperatures in excess of 543 °C, and char yields at 800 °C in nitrogen higher than 60%. The poly(amine-imide)s 6e-6g exhibited a UV-vis absorption maximum at around 300 nm in NMP solution. The poly(amine-imide) 6g derived from an aliphatic dianhydride was optically transparent in the visible region and fluoresced violet-blue at 403 nm in NMP with 4.54% quantum yield higher than the wholly aromatic 6e and 6f. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-imide) films on an indium-tin oxide (ITO)-coated glass substrate exhibited a reversible oxidation wave at 1.05 V and an additional irreversible oxidation wave at 1.39 V versus Ag/AgCl in acetonitrile solution. The polymer films revealed excellent stability of electrochromic characteristics, with a color change from neutral pale yellowish to green doped form at applied potentials ranging from 0.00 to 1.15 V. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b602133f

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Novel high-Tg poly(amine-imide)s bearing pendent N-phenylcarbazole
units: synthesis and photophysical, electrochemical and electrochromic
properties
Guey-Sheng Liou,*a Sheng-Huei Hsiaob and Hwei-Wen Chena
Received 13th February 2006, Accepted 9th March 2006
First published as an Advance Article on the web 28th March 2006
DOI: 10.1039/b602133f
A new carbazole-derived, triphenylamine-containing aromatic diamine monomer, 4,49-diamino-
40-N-carbazolyltriphenylamine, was successfully synthesized by the caesium fluoride-mediated
condensation of N-(4-aminophenyl)carbazole with 4-fluoronitrobenzene, followed by palladium-
catalyzed hydrazine reduction. A series of novel poly(amine-imide)s 6a–6g with pendent
N-phenylcarbazole units having inherent viscosities of 0.17–0.56 dL g21 were prepared from
the newly synthesized diamine monomer and seven commercially available tetracarboxylic
dianhydrides via a conventional two-step procedure that included a ring-opening polyaddition to
give polyamic acids, followed by chemical or thermal cyclodehydration. The polymers of the series
were amorphous and most of them could afford flexible, transparent, and tough films with good
mechanical properties. All the poly(amine-imide)s had useful levels of thermal stability associated
with high glass-transition temperatures (303–371 uC), 10% weight-loss temperatures in excess of
543 uC, and char yields at 800 uC in nitrogen higher than 60%. The poly(amine-imide)s 6e–6g
exhibited a UV-vis absorption maximum at around 300 nm in NMP solution. The poly(amine-
imide) 6g derived from an aliphatic dianhydride was optically transparent in the visible region and
fluoresced violet–blue at 403 nm in NMP with 4.54% quantum yield higher than the wholly
aromatic 6e and 6f. The hole-transporting and electrochromic properties were examined by
electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-
imide) films on an indium-tin oxide (ITO)-coated glass substrate exhibited a reversible oxidation
wave at 1.05 V and an additional irreversible oxidation wave at 1.39 V versus Ag/AgCl in
acetonitrile solution. The polymer films revealed excellent stability of electrochromic
characteristics, with a color change from neutral pale yellowish to green doped form at applied
potentials ranging from 0.00 to 1.15 V.
Carbazole is a conjugated unit that has interesting optical
Introduction
and electronic properties such as photoconductivity and
photorefractivity.6,7 In the field of electroluminescence,
Triarylamines have attracted considerable interest as hole
transport materials for use in multilayer organic electrolumi-
carbazole derivatives are often used as the materials for hole-
nescence (EL) devices due to their relatively high mobilities
transporting and light-emitting layers because of their high
and their low ionization potentials.1 The feasibility of utilizing
charge mobility and thermal stability, and show blue electro-
spin-coating and ink-jet printing processes for large-area EL
luminescence due to the large band gap of the improved planar
biphenyl unit by the bridging nitrogen atom.8 From a
devices and possibilities of various chemical modifications
(to improve emission efficiencies and allow patterning) make
structural point of view, carbazole differs from diphenylamine
polymeric materials containing triarylamine units very attrac-
in its planar structure since it can be further imagined as
tive.2 To enhance the hole injection ability of polymeric
bonded diphenylamine; the thermal stability of materials
emissive materials such as poly(1,4-phenylenevinylene)s (PPV)
with the incorporation of carbazolyl units therefore was
and polyfluorenes (PF), there have been several reports on
improved. In addition, carbazole can be easily functionalized
at the (3,6),9,10 (2,7)11 or N-positions,12–14 and then covalently
PPV and PF derivatives involving hole-transporting units
linked into polymeric systems, both in the main-chain15 as
such as triarylamine or carbazole groups in the emissive
p-conjugated core/main chains3 or grafting them as side chains
in a polymer4 or attaching them onto the polymer chain-ends
or the outer surface of dendritic wedges.5
building blocks and in the side-chain as pendent groups.16
It is thus worthwhile to explore the feasibility of new
carbazole-based aromatic diamines as starting monomers for
the preparation of high-performance polyimide systems with
novel optoelectronic functions.
aDepartment of Applied Chemistry, National Chi Nan University,
1 University Road, Puli, Nantou Hsien 545, Taiwan, Republic of China.
E-mail: gsliou@ncnu.edu.tw
Aromatic polyimides are well accepted as advanced mate-
rials for thin-film applications in microelectronic devices and
liquid crystal displays due to their outstanding mechanical,
bDepartment of Chemical Engineering, Tatung University, 40
Chungshan North Rd. 3rd Sec., Taipei 104, Taiwan, Republic of China
This journal is ß The Royal Society of Chemistry 2006
J. Mater. Chem., 2006, 16, 1831–1842 | 1831

View Article Online
chemical, thermal, and physical properties.17 However, the
technological applications of most polyimides are limited
by processing difficulties because of high melting or glass
transition temperatures and limited solubility in most
organic solvents due to their rigid backbones. To overcome
these limitations, polymer-structure modification becomes
necessary. One of the common approaches for increasing
solubility and processability of polyimides without sacrificing
high thermal stability is the introduction of bulky, packing-
disruptive groups into the polymer backbone.18 Recently,
we have reported the synthesis of soluble aromatic
polyimides bearing triphenylamine units in the main chain
based on N,N9-bis(4-aminophenyl)-N,N9-diphenyl-1,4-phenyl-
enediamine19 and N,N-bis(4-aminophenyl)-N9,N9-diphenyl-
1,4-phenylenediamine.20 Because of the incorporation of
bulky, propeller-shaped triphenylamine units along the poly-
mer backbone, all the polymers were amorphous, showed
good solubility in many aprotic solvents, good film-forming
capability, and exhibited high thermal stability.
dianhydride (CPDA) (5g) (TCI) were purified by recrystal-
lization from acetic anhydride. 3,39,4,49-Biphenyl-
tetracarboxylic dianhydride (BPDA) (5b) (Chriskev) and
2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride
(6FDA) (5f) (Chriskev) were purified by vacuum sublima-
tion. Tetrabutylammonium perchlorate (TBAP) (Acros) was
recrystallized twice from ethyl acetate and then dried in vacuo
prior to use. All other reagents were used as received from
commercial sources.
Synthesis of monomer
N-(4-Nitrophenyl)carbazole (1). To a solution of 16.72 g
(0.10 mol) of carbazole and 15.52 g (0.11 mol) of 4-fluoroni-
trobenzene in 70 mL of dried DMSO, 36.46 g (0.24 mol) of
dried caesium fluoride was added with stirring all at once, and
the mixture was heated at 150 uC for 15 h under nitrogen
atmosphere. The mixture was poured into 560 mL of stirred
methanol slowly, and the precipitated yellow crystals were
collected by filtration and washed thoroughly with methanol.
The product was filtered to afford 28.25 g (98% in yield) of
yellow crystals with a mp of 209–210 uC (measured by DSC at
10 uC min21) (lit.24 209–211 uC; lit.25 120–122 uC). IR (KBr):
1592, 1347 cm21 (–NO2 stretch). 1H NMR (DMSO-d6, d,
ppm): 7.33 (t, 3H, He), 7.45 (t, 3H, Hd), 7.55 (d, 2H, Hc),
7.96 (d, 2H, Hb), 8.26 (d, 2H, Hf), 8.49 (d, 2H, Ha). 13C
NMR (DMSO-d6, d, ppm): 109.8 (C6), 120.5 (C8), 121.0 (C9),
123.5 (C10), 125.4 (C2), 126.4 (C7), 127.0 (C3), 139.4 (C5),
143.0 (C1), 145.6 (C4). Anal. Calcd for C18H12N2O2 (288.30):
C, 74.99%; H, 4.20%; N, 9.72%. Found: C, 74.96%; H, 4.27%;
N, 9.85%.
The electrochemistry of triphenylamine in aprotic solvents
has been well studied.21 The triphenylamine cationic radical of
the first electron oxidation is not stable, chemical reaction
therefore follows to produce tetraphenylbenzidine by tail-to-
tail (para-positions) coupling with the loss of two protons
per dimer. When the phenyl groups were incorporated
by electron-donating substituents at the para-position of
triarylamines, the coupling reactions were greatly prevented,
thus affording stable cationic radicals.22,23 In this article, we
therefore synthesized the novel carbazole-based diamine
monomer, 4,49-diamino-40-N-carbazolyltriphenylamine (4),
and its derived poly(amine-imide)s containing electron-rich
triphenylamine groups with carbazolyl para-substituted on
the pendent phenyl ring. The general properties such as
solubility, crystallinity, and thermal and mechanical
properties are described. The electrochemical, electrochromic,
and photoluminescent properties of these polymers are
also investigated herein and are compared with those of
structurally related ones from N,N-bis(4-aminophenyl)-N9,N9-
diphenyl-1,4-phenylenediamine.20
Experimental
Materials
N-(4-Aminophenyl)carbazole (2). In a 500 mL round-bottom
flask equipped with a stirring bar, 28.83 g (0.10 mol) of nitro
compound 1 and 0.70 g of 10% Pd/C were dissolved/suspended
in 300 mL of ethanol. The suspension solution was heated to
reflux, and 15 mL of hydrazine monohydrate was added slowly
to the mixture, then the solution was stirred at reflux
temperature. After a further 9 h of reflux, the solution was
filtered hot to remove Pd/C, and the filtrate was evaporated
under reduced pressure to dryness. A yellowish syrup was
obtained. The product was used for the next step without
further purification. IR (KBr): 3368, 3448 cm21 (N–H stretch).
1H NMR (DMSO-d6, d, ppm): 6.80 (d, 2H, Ha), 7.17–7.26 (m,
5H, Hb + Hc + He), 7.36 (d, 2H, Hd), 8.17 (d, 2H, Hf), 5.44 (s,
2H, NH2). 13C NMR (DMSO-d6, d, ppm): 109.8 (C6), 114.9
(C2), 119.5 (C8), 120.5 (C9), 122.4 (C10), 124.7 (C4), 126.1 (C7),
127.9 (C3), 141.1 (C5), 148.8 (C1). Anal. Calcd for C18H14N2
N,N-Bis(4-aminophenyl)-N9,N9-diphenyl-1,4-phenylenediamine
(mp = 245–248 uC) was synthesized by the condensation of
4-aminotriphenylamine with 4-fluoronitrobenzene in the
presence of sodium hydride, followed by the hydrazine
Pd/C-catalyzed reduction of the intermediate dinitro com-
pound according to
a
previously reported procedure.20
N,N-Dimethylacetamide (DMAc) (TEDIA), N,N-dimethyl-
formamide (DMF) (Acros), dimethyl sulfoxide (DMSO)
(TEDIA), and N-methyl-2-pyrrolidinone (NMP) (TEDIA)
were used without further purification. Commercially avail-
able tetracarboxylic dianhydrides such as pyromellitic
dianhydride (PMDA) (5a) (Chriskev), 3,39,4,49-benzopheno-
netetracarboxylic dianhydride (BTDA) (5c) (Chriskev),
4,49-oxydiphthalic dianhydride (ODPA) (5d) (TCI),
3,39,4,49-diphenylsulfonetetracarboxylic dianhydride (DSDA)
(5e)
(TCI),
and
1,2,3,4-cyclopentanetetracarboxylic
1832 | J. Mater. Chem., 2006, 16, 1831–1842
This journal is ß The Royal Society of Chemistry 2006

View Article Online
(258.32): C, 83.69%; H, 5.46%; N, 10.84%. Found: C, 83.29%;
H, 5.50%; N, 10.74%.
density of crystal Dcalcd = 1.288 Mg m23 for Z = 2 and
3
V = 1322.28(4) A .
˚
4,49-Dinitro-40-N-carbazolyltriphenylamine (3). To a solution
of 18.08 g (0.07 mol) of compound 2 and 21.73 g (0.15 mol) of
4-fluoronitrobenzene in 100 mL of dried DMSO, 25.52 g
(0.17 mol) of dried caesium fluoride was added with stirring
all at once, and the mixture was heated at 150 uC for 15 h
under nitrogen atmosphere. The mixture was poured into 1 L
of saturated aqueous NaCl solution to give orange–red solids.
The crude product was further purified by recrystallization
from DMF affording orange–red needles with a mp of
302–305 uC (by DSC) in 78% yield (27.33 g). IR (KBr):
1579, 1307 cm21 (NO2 stretch). Anal. Calcd for C30H20N4O4
(500.50): C, 71.99%; H, 4.03%; N, 11.19%. Found: C, 71.94%;
H, 3.96%; N, 11.28%. Crystal data for 3: orange-red single
crystal grew by the slow crystallization from DMF, crystal
dimensions: 0.50 6 0.44 6 0.33 mm3, triclinic, space group
4,49-Diphthalimido-40-N-carbazolyltriphenylamine (4a). To a
solution of 0.18 g (0.40 mmol) of compound 4 was added
0.13 g (0.85 mmol) of phthalic anhydride in 2 mL of dried
DMF with stirring all at once. The mixture was stirred for 4 h,
followed by the addition of acetic anhydride 0.75 mL and
pyridine 0.3 mL. After being stirred for 2 h at room
temperature, the mixture was heated at 90 uC for 4 h. The
yellowish transparent solution was poured into 100 mL of
stirred methanol slowly, and the precipitated yellowish powder
was collected by filtration to afford 0.27 g (86% yield) of
yellowish powders with a mp of 328–331 uC measured by
DSC at 10 uC min21. IR (KBr): 1716 (symmetrical CLO), 1383
(C–N), and 714 cm21 (imide ring deformation).
¯
˚
˚
˚
P1, a = 9.254(6) A, b = 11.130(8) A, c = 12.368(8) A,
a = 100.153(12)u, b = 97.120(13)u, c = 98.744(13)u, Dcalcd
=
3
1.358 Mg m23, Z = 2, and V = 1224.4(14) A .
˚
4,49-Diamino-40-N-carbazolyltriphenylamine (4). In a 500 mL
round-bottom flask equipped with a stirring bar, 7.04 g
(14.00 mmol) of dinitro compound 3 and 1.00 g of 10% Pd/C
were dissolved/suspended in 400 mL of ethanol. The suspen-
sion solution was heated to reflux, and 18 mL of hydrazine
monohydrate was added slowly to the mixture, then the
solution was stirred at reflux temperature. After a further 9 h
of reflux, the solution was filtered hot to remove Pd/C, and
the filtrate was then cooled to precipitate white needles. The
product was collected by filtration and washed with ethanol,
and dried in vacuo at 80 uC to give 4.80 g (79% in yield) of
white needles with a mp of 192–195 uC (by DSC). IR (KBr):
3357, 3436 cm21 (N–H stretch). 1H NMR (DMSO-d6, d, ppm):
6.65 (d, 4H, Hh), 6.82 (d, 2H, Ha), 6.99 (d, 4H, Hg), 7.23 (t, 4H,
Hb + He), 7.30 (d, 2H, Hc), 7.39 (t, 2H, Hd), 8.18 (d, 2H, Hf),
5.04 (s, 4H, NH2). 13C NMR (DMSO-d6, d, ppm): 109.6 (C6),
115.0 (C13), 116.5 (C2), 119.5 (C8), 120.3 (C9), 122.3 (C10),
125.9 (C7), 126.0 (C1), 127.2 (C3), 127.8 (C12), 135.4 (C11),
140.7 (C5), 146.0 (C14), 149.1 (C4). Anal. Calcd for C30H24N4
(440.55): C, 81.79%; H, 5.49%; N, 12.72%. Found: C, 81.72%;
H, 5.41%; N, 12.63%. Crystal data for 4?THF: colorless
single crystal (a crystallosolvate with THF) grew by slow
evaporation of its tetrahydrofuran (THF)–ethanol solution,
crystal dimensions: 0.70 6 0.60 6 0.50 mm3, triclinic, space
Polymer synthesis. poly(amine-imide)s 6a–6d by two-step
method via thermal imidization reaction
The poly(amine-imide)s 6a–6d were synthesized from diamine
4 and dianhydrides 5a–5d by the conventional two-step
method via thermal imidization. The synthesis of poly(amine-
imide) 6b was used as an example to illustrate the general
synthetic route used to produce the poly(amine-imide)s. To a
solution of 0.60 g (1.36 mmol) of diamine 4 in 9.5 mL of
DMAc, 0.40 g (1.36 mmol) of dianhydride BPDA (5b) was
added in one portion. The mixture was stirred at room
temperature overnight (ca. 12 h) to afford a viscous poly(amic
acid) solution. The inherent viscosity of the resulting poly(amic
acid) was 0.98 dL g21, measured in DMAc at a concentration
of 0.5 g dL21 at 30 uC. The poly(amic acid) film was obtained
by casting from the reaction polymer solution onto a glass
plate and drying at 90 uC under vacuum. The poly(amic acid)
¯
˚
˚
˚
group P1, a = 11.242(2) A, b = 11.818(2) A, c = 11.950(2) A,
a = 100.705(10)u, b = 105.972(10)u, c = 113.247(10)u, where the
This journal is ß The Royal Society of Chemistry 2006
J. Mater. Chem., 2006, 16, 1831–1842 | 1833

View Article Online
in film form was converted to poly(amine-imide) 6b by
successive heating under vacuum at 100 uC for 1 h, 200 uC
for 1 h, and then 300 uC for 1 h. The inherent viscosity of
poly(amine-imide) 6b was 0.56 dL g21, measured at a
concentration of 0.5 g dL21 in concentrated sulfuric acid at
30 uC. Anal. Calcd for (C46H26N4O4)n (698.72)n: C, 79.07%; H,
3.75%; N, 8.02%. Found: C, 77.70%; H, 3.77%; N, 7.85%.
Measurements were performed at room temperature with film
specimens (0.5 cm width, 6 cm length), and an average of at
least three replicates was used. Thermogravimetric analysis
(TGA) was conducted with a Perkin Elmer Pyris 1 TGA.
Experiments were carried out on approximately 6–8 mg
film samples heated in flowing nitrogen or air (flow rate =
20 cm3 min21) at a heating rate of 20 uC min21. DSC analyses
were performed on a Perkin Elmer Pyris Diamond DSC at a
scan rate of 20 uC min21 in flowing nitrogen (20 cm3 min21).
Thermomechanical analysis (TMA) was conducted with a
Perkin Elmer TMA 7 instrument. The TMA experiments were
conducted from 50 to 350 uC at a scan rate of 10 uC min21 with
a penetration probe 1.0 mm in diameter under an applied
constant load of 10 mN. Softening temperatures (Ts) were
taken as the onset temperatures of probe displacement on
the TMA traces. Cyclic voltammetry was performed with a
Bioanalytical System Model CV-27 potentiostat and a BAS
X-Y recorder with ITO (polymer films area about 0.7 cm 6
0.5 cm) as a working electrode and a platinum wire as
an auxiliary electrode at a scan rate of 100 mV s21 against a
Ag/AgCl reference electrode in a solution of 0.1 M tetra-
butylammonium perchlorate (TBAP)–acetonitrile (CH3CN).
Voltammograms are presented with the positive potential
pointing to the left and with increasing anodic currents
pointing downwards. The spectroelectrochemical cell was
composed of a 1 cm cuvette, ITO as a working electrode, a
platinum wire as an auxiliary electrode, and a Ag/AgCl
reference electrode. Absorption spectra in spectroelectro-
chemical analysis were measured with a HP 8453 UV-Visible
spectrophotometer. Photoluminescence spectra were mea-
sured with a Jasco FP-6300 spectrofluorometer. Fluorescence
quantum yields (WF) of the samples in NMP were measured
by using quinine sulfate in 1 N H2SO4 as a reference standard
(WF = 0.546).26 All corrected fluorescence excitation spectra
were found to be equivalent to their respective absorption
spectra.
Poly(amine-imide)s 6e–6g by two-step method via chemical
imidization reaction
The poly(amine-imide)s 6e–6g were synthesized from diamine 4
and dianhydrides 5e–5g by the conventional two-step method
via chemical imidization. The synthesis of poly(amine-imide)
6e was used as an example to illustrate the general synthetic
route used to produce the poly(amine-imide)s. To a solution of
0.55 g (1.25 mmol) of diamine 4 in 9.5 mL of DMAc, 0.45 g
(1.25 mmol) of dianhydride DSDA (5e) was added in one
portion. The mixture was stirred at room temperature over-
night (ca. 12 h) to afford a viscous poly(amic acid) solution.
The inherent viscosity of the resulting poly(amic acid) was
0.98 dL g21, measured in DMAc at a concentration of
0.5 g dL21 at 30 uC. The poly(amic acid) was subsequently
converted to poly(amine-imide) 6e via a chemical imidization
process by addition of pyridine 2 mL and acetic anhydride
5 mL, and the mixture was heated at 100 uC for 2 h to effect
complete imidization. The resulting polymer solution was
poured into 300 mL of methanol giving a fibrous precipitate,
which was washed thoroughly with methanol, and collected
by filtration. The precipitate was dissolved in 8 mL of NMP,
and the homogeneous solution was poured into a 9 cm glass
culture dish, which was placed in a 90 uC oven for 12 h
to remove the solvent. Then, the obtained film was further
dried in vacuo at 150 uC for 6 h. The inherent viscosity of
poly(amine-imide) 6e was 0.47 dL g21 in NMP at
a
concentration of 0.5 g dL21 at 30 uC. Anal. Calcd for
(C46H26N4O6S)n (762.79)n: C, 72.43%; H, 3.44%; N, 7.35%; S,
4.20%. Found: C, 71.62%; H, 3.66%; N, 7.34%; S, 4.25%.
Results and discussion
Measurements
Monomer synthesis
N-(4-Aminophenyl)carbazole (2)24 was prepared by the
caesium fluoride-mediated aromatic nucleophilic substitution
reaction of carbazole with 4-fluoronitrobenzene followed by
hydrazine Pd/C-catalytic reduction according to the synthetic
route outlined in Scheme 1. The new aromatic diamine having
a bulky pendent N-phenylcarbazole group, 4,49-diamino-40-
N-carbazolyltriphenylamine (4), was successfully synthesized
by hydrazine Pd/C-catalyzed reduction of the dinitro com-
pound 3 resulting from double N-arylation reaction of
compound 2 with 4-fluoronitrobenzene in the presence of
caesium fluoride. Elemental analysis, IR, and 1H and 13C
NMR spectroscopic techniques were used to identify struc-
tures of the intermediate compounds 1, 2, and 3 and the target
Infrared spectra were recorded on a Perkin Elmer RXI FT-IR
spectrometer. Elemental analyses were run in a VarioEL-III
Elementar. 1H and 13C NMR spectra were measured on a
Bruker AV-500 FT-NMR system. X-Ray single-crystal
diffraction experiments were carried on a Norius Kappa
CCD four-circle diffractometer equipped with graphite-mono-
chromated Mo-Ka radiation. The structures were solved by
direct methods using SHELXL-97 software (Sheldrick, 1997).
The inherent viscosities were determined at 0.5 g dL21
concentration using a Tamson TV-2000 viscometer at 30 uC.
Wide-angle X-ray diffraction (WAXD) measurements were
performed at room temperature (ca. 25 uC) on a Shimadzu
XRD-7000 X-ray diffractometer (40 kV, 20 mA), using
graphite-monochromatized Cu-Ka radiation. Ultraviolet-
visible (UV-vis) spectra of the polymer films were recorded
on a Varian Cary 50 Probe spectrometer. An Instron universal
tester model 4400R with a 5 kg load cell was used to study the
stress–strain behavior of the samples. A gauge length of 2 cm
and a crosshead speed of 5 mm min21 were used for this study.
1
diamine monomer 4. Fig. 1 illustrates the H NMR and 13C
NMR spectra of the diamine monomer 4. Assignments of each
carbon and proton are assisted by the two-dimensional NMR
spectra shown in Figs. 2 and 3, and these spectra agree well
with the proposed molecular structure of compound 4. The
molecular structures of compounds 3 and 4 were further
1834 | J. Mater. Chem., 2006, 16, 1831–1842
This journal is ß The Royal Society of Chemistry 2006

View Article Online
Fig. 2 H–H COSY spectrum of diamine 4 in DMSO-d6.
Scheme 1
Fig. 1 (a) 1H NMR and (b) 13C NMR spectra of compound 4 in
DMSO-d6.
Fig. 3 C–H COSY spectrum of diamine 4 in DMSO-d6.
J. Mater. Chem., 2006, 16, 1831–1842 | 1835
This journal is ß The Royal Society of Chemistry 2006

View Article Online
Fig. 4 X-Ray structures of (a) dinitro compound 3 and (b) the crystalline solvate of diamine monomer 4 with THF.
confirmed by single-crystal X-ray diffractions (Fig. 4). The
single crystals of 3 were acquired by slow crystallization of
a DMF solution. On the other hand, the crystal of 4 contains
THF, one of the components of the mixed solvents, in a ratio
of 1 : 1 with 4, as shown in Fig. 4(b). The molecular structure
of 4 is very similar to that of 3 apart from replacement of
nitro by amino substituents. As shown in Fig. 4, the molecular
structures display a coplanar structure of the carbazolyl
unit and a propeller-shaped conformation of the triphenyl-
amine core.
from N,N-bis(4-aminophenyl)-N9,N9-diphenyl-1,4-phenylene-
diamine and dianhydrides 5a–5g.
Basic characterization
The color of polyimide films depends markedly on the
chemical structure of the dianhydride components (Table 1).
The colors of poly(amine-imide) 6a–6f films were from
yellowish to deep reddish or brownish that could be attributed
to charge-transfer complex (CTC) formation between the
electron-donating amino unit and the strongly electron-
accepting pyromellitimide or phthalimide unit. Due to effective
diminution of the conjugation and intermolecular CTC
formation by aliphatic tetracarboxylic dianhydride (CPDA),
the film of poly(amine-imide) 6g was less colored.27 As
mentioned previously, the poly(amine-imide)s 6b–6f could
afford flexible, transparent, and tough films. These films
were subjected to tensile testing, and the results are given
in Table 2. The tensile strengths, elongations to break, and
initial moduli of these films were in the ranges of 71–110 MPa,
6–18% and 2.1–3.0 GPa, respectively. The WAXD studies of
the poly(amine-imide)s indicated that all the polymers
were essentially amorphous. The amorphous nature can be
attributed to the introduction of bulky, twisted, three-
dimensional N-carbazolyl-substituted triphenylamino units
along the polymer backbone.
Polymer synthesis
A series of novel poly(amine-imide)s 6a–6g bearing pendent
N-phenylcarbazole units were prepared by the reaction of
diamine 4 with seven commercially available dianhydrides
5a–5g in DMAc at room temperature to form the precursor
poly(amic acid)s, followed by chemical or thermal imidization
(Scheme 2). In the first step, the viscosities of the reaction
mixtures became very high as poly(amic acid)s were formed,
indicating the formation of high molecular weight polymers.
The thermal conversion to polyimides was carried out by
successive heating of the poly(amic acid) films to 300 uC
in vacuo. The poly(amic acid) precursors also could be
chemically dehydrated to the polyimides by treatment with
acetic anhydride and pyridine. All poly(amine-imide)s could
afford good, free-standing films, although the films of 6a and
6g might crack on fingernail creasing because of structural
rigidity or lower molecular weight (for 6g). The formation
of poly(amine-imide)s was confirmed with elemental analysis,
IR, and NMR spectroscopy. The inherent viscosities and
elemental analysis data of these poly(amine-imide)s are
summarized in Table 1. The IR spectra of these polymers
exhibited characteristic imide absorption bands at around 1775
(symmetrical CLO), 1716 (symmetrical CLO), 1383 (C–N), and
714 cm21 (imide ring deformation). The microstructures
of these poly(amine-imide)s were also verified by the high-
resolution NMR spectra. For a comparative study, a series of
referenced poly(amine-imide)s 69a–69g were also synthesized
The solubility behavior of polymers 6a–6g obtained by
thermal or chemical imidization was investigated qualitatively,
and the results are listed in Table 3. The solubility behavior of
the polyimides depended on their chain packing ability and
intermolecular interactions that was affected by the rigidity,
symmetry, and regularity of the molecular backbone. Except
for poly(amine-imide)s derived from more rigid dianhydrides,
such as 5a–5d, the other poly(amine-imide)s 6e–6f exhibited
higher solubility in polar aprotic organic solvents such as
NMP, DMAc, DMF, and m-cresol. The poly(amine-imide)s 6f
and 6g were soluble not only in polar aprotic organic solvents
but also in less polar solvents such as chloroform and THF.
Their excellent solubility can be attributable to the existence of
1836 | J. Mater. Chem., 2006, 16, 1831–1842
This journal is ß The Royal Society of Chemistry 2006

View Article Online
method. Thus, the difference in solubility of poly(amine-
imide)s obtained by different methods could be ascribed to
morphological change of the polymers during heat treatment
resulting in some degree of ordering from molecular aggrega-
tion of the polymer chain segments.
The thermal properties of these poly(amine-imide)s are
summarized in Table 4. Typical TGA curves for poly(amine-
imide) 6c and 69c are reproduced in Fig. 5. All of the
poly(amine-imide)s exhibited a similar TGA pattern with no
significant weight loss below 500 uC in air or nitrogen atmo-
sphere. The 10% weight-loss temperatures of the poly(amine-
imide)s in nitrogen and air were recorded in the range of
543–652 uC and 549–634 uC, respectively. The amount of
carbonized residue (char yield) of these polymers in nitrogen
atmosphere was more than 60% at 800 uC. The high char yields
of these polymers can be ascribed to their high aromatic
content. The relatively lower stability of 6g is reasonable
when considering its less stable aliphatic segments. The glass-
transition temperatures (Tgs) of all the polymers were observed
in the range of 303–371 uC by DSC and decreased with
decreasing rigidity and symmetry of the aromatic tetra-
carboxylic dianhydride. As shown in Table 4, the thermal
properties compared with the analogous poly(amine-imide)s
69a–69f, the 6 series of poly(amine-imide)s showed an increased
Tg and an enhanced thermal stability (Fig. 5) because of the
decreased conformational flexibility or free volume caused by
the introduction of planar carbazole groups in the repeat unit.
All the polymers indicated no clear melting endotherms up to
the decomposition temperatures on the DSC thermograms.
The softening temperatures (Ts) (may be referred to as
apparent Tg) of the polymer film samples were determined
by the TMA method with a loaded penetration probe. They
were obtained from the onset temperature of the probe
displacement on the TMA trace. A typical TMA thermogram
for poly(amine-imide) 6e is illustrated in Fig. 6. In most cases,
the Ts values obtained by TMA are comparable to the Tg
values measured by the DSC experiments (Table 4).
Optical and electrochemical properties
The optical and electrochemical properties of the poly(amine-
imide)s were investigated by UV-vis and photoluminescence
(PL) spectroscopy and cyclic voltammetry. The results are
summarized in Table 5. The organosoluble polymers 6e–6g
exhibited UV-vis absorption bands with lmax at 295–340 nm
in NMP solutions, assignable to the p–p* transition resulting
from the conjugation between the aromatic rings and nitrogen
atoms that combines the characteristic p–p* transitions of
triphenylamine moieties (295–310 nm) and carbazole chromo-
phores (320–340 nm).25 In the solid film, the poly(amine-
imide)s showed absorption characteristics (lmax around
320–330 nm) similar to those in the solution. Fig. 7 shows
solution UV-vis absorption and PL emission spectra of
poly(amine-imide)s 6e–g in NMP at a concentration of around
1 6 1025 mol L21. These carbazole-based poly(amine-imide)s
exhibited a violet–blue fluorescence emission maximum at
around 402–455 nm in the NMP solution. The fluorescence
quantum yield in NMP solution ranges from 0.61% for 6f to
4.54% for 6g. The blue shift and higher fluorescence quantum
Scheme 2
the hexafluoroisopropylidene and alicyclic structure which
limit the CTC formation and reduce the intermolecular
interactions. In addition, the poly(amine-imide)s prepared by
the chemical imidization method had better solubility as
compared with those by the two-step thermal imidization
This journal is ß The Royal Society of Chemistry 2006
J. Mater. Chem., 2006, 16, 1831–1842 | 1837

View Article Online
Table 1 Inherent viscosity and elemental analysis of poly(amine-imide)s
Poly(amine-imide)s Elemental analysis (%) of poly(amine-imide)s
Code
6a
6b
6c
ginha/dL g21
Color of filmb
dark brown
dark orange
orange–red
yellow–brown
orange–red
yellow–brown
off-white
Formula (formula weight)
(C40H22N4O4)n (622.63)n
(C46H26N4O4)n (698.72)n
(C47H26N4O5)n (726.73)n
(C46H26N4O5)n (714.72)n
(C46H26N4O6S)n (762.79)n
(C49H26F6N4O4)n (848.75)n
(C39H26N4O4)n (614.65)n
C
H
N
S
0.45
0.56
0.33
0.46
0.47
0.55
0.17
Calcd
Found
Calcd
Found
Calcd
Found
Calcd
Found
Calcd
Found
Calcd
Found
Calcd
Found
77.16
75.49
79.07
77.70
77.68
77.46
77.30
76.27
72.43
71.62
69.34
67.40
76.21
74.10
3.56
3.75
3.75
3.77
3.61
3.91
3.67
3.81
3.44
3.66
3.09
3.28
4.26
4.78
9.00
8.97
8.02
7.85
7.71
7.95
7.84
7.79
7.35
7.34
6.60
6.22
9.12
9.00
6d
6e
4.20
4.25
6f
6g
a
Measured at a polymer concentration of 0.5 g dL21 in NMP at 30 uC (6a, 6b, 6c, and 6d measured in concentrated sulfuric acid).
Thickness: 6a–6f: 60–90 mm; 6g: 4 mm.
b
Table 2 Mechanical properties of poly(amine-imide) films
appeared red–brown to deep brown color as shown in Table 1.
In contrast, the poly(amine-imide) 6g and 69g showed a light
color and high optical transparency with cutoff wavelength
in the range of 340–351 nm due to lower capability of
intermolecular CTC formation.
Tensile
strength/MPa
Elongation
at break (%)
Initial
modulus/GPa
Polymer
6b
6c
6d
6e
6f
129
101
83
110
87
18
8
6
6
9
2.0
2.1
2.3
3.0
1.9
The electrochemical behavior of the 6 and 69 series of
poly(amine-imide)s was investigated by a cyclic voltammetry
technique conducted for a cast film on an ITO-coated glass
substrate as working electrode in dry acetonitrile (CH3CN)
containing 0.1 M of TBAP as the supporting electrolyte and
saturated Ag/AgCl as the reference electrode under nitrogen
atmosphere. Fig. 9 shows the typical cyclic voltammograms of
poly(amine-imide)s 6f and 69f. All the 6 series poly(amine-
imide)s reveal one reversible redox couple at a half-wave
potential (E1/2) of 1.05–1.10 V and one irreversible oxidation
redox wave at E1/2 = 1.39–1.44 V under an anodic sweep. The
first electron removal for poly(amine-imide) 6f is assumed to
occur at the nitrogen atom on the main chain triphenylamine
unit, which is more electron-rich than the nitrogen atom on the
pendent carbazolyl moiety. This electrochemical behavior was
also evidenced by comparing N-phenylcarbazole with the
yield of light-colored 6g compared to 6e–6f could be attributed
to the incorporation of aliphatic tetracarboxylic dianhydride
(CPDA) into the polymer backbone, which effectively reduce
the conjugation and the formation of intermolecular CTC. The
photoluminescence of the polymer thin films of 6g and 69g
under UV irradiation is shown in Fig. 8, and these two
films fluoresce violet and deep blue, respectively. The cutoff
wavelengths (absorption edge; l0) from the UV-vis trans-
mittance spectra are also included in Table 5. It revealed that
most of the visible region can be absorbed by poly(amine-
imide)s 6a, 6c and 6e which show higher l0 values. This is
consistent with the fact that the films of these polymers
Table 3 Solubility of poly(amine-imide)sa
Solvent
Polymer
Method of preparationb
NMP
DMAc
DMF
DMSO
m-Cresol
THF
Chloroform
6a
6b
6c
6d
6e
6f
6g
a
two-step (T)
two-step (C)
two-step (T)
two-step (C)
two-step (T)
two-step (C)
two-step (T)
two-step (C)
two-step (T)
two-step (C)
two-step (T)
two-step (C)
two-step (T)
two-step (C)
—
¡
—
¡
S
¡
¡
¡
+
++
++
++
++
++
—
¡
—
—
—
—
—
—
+
++
++
++
++
++
—
¡
—
—
—
—
—
—
+
¡
++
++
++
++
—
¡
—
—
S
—
—
+
—
—
—
—
—
—
—
—
—
—
++
++
—
++
—
—
—
—
—
—
—
—
—
—
++
++
—
++
+
S
+
—
—
—
+
—
+
+
+
+
+
+
++
+
+
+
++
++
Qualitative solubility was tested with 1 mg of a sample in 1 mL of stirred solvent. ++: soluble at room temperature; +: soluble on heating; ¡:
b
partially soluble; S: swelling; —: insoluble even on heating. (T): thermal imidization; (C): chemical imidization.
1838 | J. Mater. Chem., 2006, 16, 1831–1842
This journal is ß The Royal Society of Chemistry 2006

View Article Online
Table 4 Thermal properties of poly(amine-imide)sa
Td at 5% weight loss/uCd
Td at 10% weight loss/uCd
Polymer
Tg/uCb
Ts/uCc
in N2
in air
in N2
in air
Char yield (wt%)e
6a
6b
6c
6d
6e
6f
6g
a
371 (352)f
325 (302)
312 (294)
303 (264)
326 (305)
310 (286)
345
353
324
304
299
328
304
320
620
631
599
630
537
604
519
603
607
592
607
529
553
483
640 (624)
652 (629)
623 (618)
648 (610)
614 (568)
642 (585)
543
627 (610)
634 (622)
621 (589)
627 (600)
584 (582)
576 (574)
549
72 (68)
74 (70)
68 (63)
73 (74)
68 (67)
72 (68)
60
b
The polymer film samples were heated at 300 uC for 1 h prior to all the thermal analyses. Midpoint temperature of baseline shift on the
second DSC heating trace (rate 20 uC min21) of the sample after quenching from 400 uC. Softening temperature measured by TMA with a
c
constant applied load of 10 mN at a heating rate of 10 uC min21
.
Decomposition temperature, recorded via TGA at a heating rate of
d
20 uC min21 and a gas-flow rate of 30 cm3 min21
structurally similar poly(amine-imide)s 69a–69f having the corresponding dianhydride residue as in the 6 series.
.
Residual weight percentage at 800 uC in nitrogen. Data in parentheses are those of
e
f
Fig. 6 TMA curve of poly(amine-imide) 6e with a heating rate of
10 uC min21
.
Fig. 5 TGA thermograms of poly(amine-imide) 6c and 69c at a scan
rate of 20 uC min21
.
(E1/2) and the onset absorption wavelength of the UV-vis
spectra, and the results are listed in Table 5. For example, the
oxidation half-wave potential for poly(amine-imide) 6f has
been determined as 1.10 V vs. Ag/Ag+. The external ferrocene/
ferrocenium (Fc/Fc+) redox standard E1/2 is 0.44 V vs. Ag/Ag+
in CH3CN. Assuming that the HOMO energy for the Fc/Fc+
standard is 4.80 eV with respect to the zero vacuum level, the
HOMO energy for poly(amine-imide) 6f has been evaluated to
be 5.46 eV. In comparison, the 69 series polymers exhibited
lower first oxidation potentials and HOMO values than the
corresponding 6 series. This could be attributed to the fact
model compound, 4,49-diphthalimido-40-N-carbazolyltriphe-
nylamine 4a. N-Phenylcarbazole showed one irreversible peak
in CH3CN (Ep,a = 1.35 V). In contrast, the model compound
4a exhibited a reversible first oxidation at E1/2 = 1.09 V and an
irreversible second oxidation at Ep,a = 1.35 V. The oxidation
potential of N-phenylcarbazole is similar to the second
oxidation potential of model compound 4a at Ep,a = 1.35 V.
Thus, the first stable cationic radical of poly(amine-imide)s+
?
should be formed by the first oxidation at the nitrogen atom of
the triphenylamine unit. The energy levels of the HOMO and
LUMO of the investigated poly(amine-imide)s can be esti-
mated from the oxidation onset (Eonset) or half-wave potentials
that the pendent triphenylamine unit of the 69 series (Ep,a
=
0.80 V in CH3CN)20 is easier to oxidize than N-phenylcarba-
zole (Ep,a = 1.35 V in CH3CN).
This journal is ß The Royal Society of Chemistry 2006
J. Mater. Chem., 2006, 16, 1831–1842 | 1839

View Article Online
Table 5 Optical and electrochemical properties for poly(amine-imide)s
Solution l/nmb
Film l/nm
E1/2/V (vs. Ag/AgCl in CH3CN)
h
Eg
eV
/
HOMOi/ LUMOj/
Indexa Abs max. PL max. WF (%)d l0
Abs max. Abs onset PL max.f 1st
2nd
eV
eV
e
6a
6b
6c
6d
6e
6f
—
—
—
—
—
—
—
—
—
—
—
—
0.76
0.61
4.54
1.10
0.30
1.04
1.57
628 320
530 331
543 318
488 328
534 328
485 329
351 331
502 334
610 309
506 330
340 323
419
387
392
378
392
377
367
397
405
393
388
—
—
—
—
—
—
398
—
—
—
424
1.05
1.07
1.05
1.06
1.08
1.10
1.08
0.79
0.81
0.81
0.73
(1.44)g
(1.42)g
(1.40)g
(1.42)g
(1.43)g
(1.44)g
(1.39)g
1.14
2.96 5.41
3.20 5.43
3.16 5.41
3.28 5.42
3.16 5.44
3.29 5.46
3.38 5.44
3.12 5.15
3.06 5.17
3.16 5.17
3.20 5.09
2.45
2.23
2.25
2.14
2.28
2.17
2.06
2.03
2.11
2.01
1.89
295 (340)c 455
295 (341)c 431
295 (340)c 402
6g
69d
69e
69f
69g
a
(311)c
(309)c
(308)c
(314)c
459
426
458
436
1.15
1.16
1.11
6 and 69 series as shown in Table 4 footnotes. 6a–6a are difficult to dissolve in NMP. Polymer concentration of 1 6 1025 mol L21 in
b
c
NMP. Excitation wavelength. The quantum yield in dilute solution was calculated with quinine sulfate as the standard (WF = 0.546). The
d
e
f
cutoff wavelength from the UV-vis transmission spectra of polymer films. They were excited at the same wavelength for solid and solution
g
h
state. —: No discernible lPL was observed. The second oxidation redox couples are irreversible for 6a–6g. The data were calculated from
i
polymer film by the equation: gap = 1240/lonset
.
The HOMO energy levels were calculated from cyclic voltammetry and were referenced to
j
ferrocene (4.8 eV). LUMO = HOMO 2 gap.
Fig. 8 Emission colors of the polymer films of 6g and 69g when
exposed to a standard laboratory UV lamp (l around 365 nm, film
thickness = 4–6 mm).
Fig. 7 UV-vis and PL spectra of solutions of poly(amine-imide)s 6e,
6f, and 6g in NMP (1 6 1025 M). A solution of quinine sulfate in 1 N
H2SO4 (aq) with a concentration of 1 6 1025 M was used as the
reference standard (WF = 0.546). Photographs show the appearance
of the sample solutions before and after exposure to a standard
laboratory UV lamp.
Electrochromic characterization
Spectroelectrochemical analysis of the poly(amine-imide) films
was carried out on an ITO-coated glass substrate, and they
showed multicolor electrochromic behavior when the applied
potential was changed. The color of the polymers was changed
from neutral pale yellow or orange to green and to blue. The
typical spectroelectrochemical behavior of poly(amine-imide)
6f at various applied potentials is depicted in Fig. 10. When the
applied potential was increased positively from 0.00 to 1.15 V,
the peak of the characteristic absorbance at 312 nm for
Fig. 9 Cyclic voltammograms of the cast films of poly(amine-imide)
6f and 69f on an ITO-coated glass substrate in 0.1 M TBAP–CH3CN at
a scan rate of 100 mV s21. (a) Ferrocene; (b), (b)9 first redox couple;
(c), (c)9 first and second redox couples.
1840 | J. Mater. Chem., 2006, 16, 1831–1842
This journal is ß The Royal Society of Chemistry 2006

View Article Online
for switching absorbance at 398 and 655 nm and 1.5 s for
bleaching. After ten continuous cyclic scans between 0.00 and
1.15 V, the polymer films still exhibited excellent stability of
electrochromic characteristics.
Conclusions
The new carbazole-based aromatic diamine monomer,
4,49-diamino-40-N-carbazolyltriphenylamine 4, was success-
fully synthesized in high purity and good yield. Novel
poly(amine-imide)s bearing pendent N-phenylcarbazole units
were prepared by the two-step method starting from the
diamine with various tetracarboxylic dianhydrides. All the
poly(amine-imide)s were amorphous with high Tg and
exhibited excellent thermal stability and useful mechanical
properties (e.g. flexibility). The semi-aromatic poly(amine-
imide) 6g showed light color and high optical transparency and
exhibited violet–blue photoluminescence both in film state
and in NMP solution with about a 4.54% quantum yield. The
poly(amine-imide) films showed good adherent behavior and
were found to be electroactive. The multicolor electrochromic
behavior of the polymer films exhibited pale yellow, green, and
blue colors when various potentials were applied. All obtained
poly(amine-imide)s revealed good stability of electrochromic
characteristics for the first oxidation state, changing color
from the yellowish neutral form to the green oxidized forms
when scanning potentials positively from 0.00 to 1.15 V. Thus,
our novel poly(amine-imide)s can be employed as potential
candidates in the development of dynamic electrochromic and
EL devices due to their suitable HOMO value, excellent
thermal stability and reversible electrochemical behavior.
Fig. 10 In situ spectroelectrochemical series of
a cast film of
poly(amine-imide) 6f in 0.1 M TBAP–CH3CN at various applied
potentials vs. Ag/Ag+: (a) 0.00, (b) 0.90, (c) 1.00, (d) 1.05, (e) 1.10, and
(f) 1.15 V.
poly(amine-imide) 6f decreased gradually while three new
bands grew up at 398, 655, and 1090 nm due to the first
electron oxidation. The new spectrum was assigned as that of
+
?
the stable cationic radical poly(amine-imide) . As the applied
potential increased to the oxidation side, the film color
changed from pale yellow to green (as shown in Fig. 10).
The second oxidation generated electrochemically was not
very stable as time passed at applied potentials higher than
1.35 V. When the applied potential was higher than 1.5 V, the
film color was changed from green to dark blue.
The stability and response time upon electrochromic
switching of the polymer film between its neutral and oxidized
forms in the visible (398 and 655 nm) was monitored (Fig. 11).
The color switching times were estimated by applying a
potential step, and the absorbance profiles were followed. The
switching time was defined as the time required to reach 90%
of the full change in absorbance after switching potential. The
thin film from poly(amine-imide) 6f would require 3 s at 1.15 V
Acknowledgements
We are grateful to the National Science Council of the
Republic of China for financial support of this work.
References
1 (a) C. W. Tang and S. A. VanSlyke, Appl. Phys. Lett., 1987, 51,
913; (b) C. W. Tang, S. A. VanSlyke and C. H. Chen, J. Appl.
Phys., 1989, 85, 3610; (c) C. Adachi, K. Nagai and N. Tamoto,
Appl. Phys. Lett., 1995, 66, 2679; (d) Y. Shirota, J. Mater. Chem.,
2000, 10, 1; (e) Y. Shirota, J. Mater. Chem., 2005, 15, 79.
2 (a) E. Bellmann, S. E. Shaheen, S. Thayumannvan, S. Barlow,
R. H. Grubbs, S. R. Marder, B. Kippelen and N. Peyghambarian,
Chem. Mater., 1998, 10, 1668; (b) E. Bellmann, S. E. Shaheen,
R. H. Grubbs, S. R. Marder, B. Kippelen and N. Peyghambarian,
Chem. Mater., 1999, 11, 399; (c) J. P. Lu, A. R. Hlil, Y. Sun,
A. S. Hay, T. Maindron, J.-P. Dodelet and M. D’Iorio, Chem.
Mater., 1999, 11, 2501; (d) X. Q. Wang, M. Nakao, K. Ogino,
H. Sato and H. M. Tan, Macromol. Chem. Phys., 2001, 202, 117;
(e) X. Q. Wang, Z. J. Chen, K. Ogino, H. Sato, K. Strzelec,
S. Miyata, Y. J. Luo and H. M. Tan, Macromol. Chem. Phys.,
2002, 203, 739; (f) Q. Fang and T. Yamamoto, Macromolecules,
2004, 37, 5894; (g) H. B. Xiao, B. Leng and H. Tian, Polymer,
2005, 46, 5705; (h) J.-S. Cho, A. Kimoto, M. Higuchi and
K. Yamamoto, Macromol. Chem. Phys., 2005, 206, 635; (i)
M. H. Sun, J. Li, B. S. Li, Y. Q. Fu and Z. S. Bo, Macro-
molecules, 2005, 38, 2651.
3 (a) Y. Q. Liu, M. S. Liu, X.-C. Li and A. K.-Y. Jen, Chem. Mater.,
1998, 10, 3301; (b) X.-C. Li, Y. Q. Liu, M. S. Liu and A. K.-Y. Jen,
Chem. Mater., 1999, 11, 1568; (c) M. Redecker, D. D. C. Bradley,
M. Inbasekaran, W. W. Wu and E. P. Woo, Adv. Mater., 1999, 11,
241; (d) C. Ego, A. C. Grimsdale, F. Uckert, G. Yu, G. Srdanov
Fig. 11 Variation of absorbance for a cast film of poly(amine-imide)
6f as a function of time for ten switches between 0.00 and 1.15 V vs.
Ag/Ag+ in 0.1 M TBAP–CH3CN.
This journal is ß The Royal Society of Chemistry 2006
J. Mater. Chem., 2006, 16, 1831–1842 | 1841

View Article Online
and K. Mullen, Adv. Mater., 2002, 14, 809; (e) C.-F. Shu,
R. Dodda, F.-I. Wu, M. S. Liu and A. K.-Y. Jen, Macro-
molecules, 2003, 36, 6698; (f) F.-I. Wu, P.-I. Shih, C.-F. Shu,
Y.-L. Tung and Y. Chi, Macromolecules, 2005, 38, 9028.
4 (a) Y.-J. Pu, M. Soma, J. Kido and H. Nishide, Chem. Mater.,
2001, 13, 3817; (b) F. S. Liang, Y.-J. Pu, T. Kurata, J. Kido and
H. Nishide, Polymer, 2005, 46, 3767; (c) F. S. Liang, T. Kurata,
H. Nishide and J. Kido, J. Polym. Sci., Part A: Polym. Chem.,
2005, 43, 5765.
5 (a) T. Miteva, A. Meisel, W. Knoll, H. G. Nothofer, U. Scherf,
D. C. Muller, K. Meerholz, A. Yasuda and D. Neher, Adv. Mater.,
2001, 13, 565; (b) Y. Q. Fu, Y. Li, J. Li, S. K. Yan and Z. S. Bo,
Macromolecules, 2004, 37, 6395.
6 J. V. Grazulevicius, P. Strohriegl, J. Pielichowski and
K. Pielichowski, Prog. Polym. Sci., 2003, 28, 1297.
7 H. Sasabe, Supramol. Sci., 1996, 3, 91.
8 J. F. Morin and M. Leclerc, Macromolecules, 2002, 35, 8413.
9 Z.-B. Zhang, M. Fujiki, H.-Z. Tang, M. Motonaga and
K. Torimitsu, Macromolecules, 2002, 35, 1988.
10 S. Brizius, U. H. Kroth and F. Bunz, Macromolecules, 2002, 35,
5317.
11 J. Bouchard, M. Belletele, G. Durocher and M. Leclerc,
Macromolecules, 2003, 36, 4624.
12 K. L. Paik, N. S. Baek and H. K. Kim, Macromolecules, 2003, 35,
6782.
13 F. Sanda, T. Kawaguchi, T. Masuda and N. Kobayashi,
Macromolecules, 2003, 36, 2224.
16 (a) J. Gratt and R.-E. Cohen, Macromolecules, 1997, 30, 3137; (b)
J. Hwang, J. Sohn and S. Y. P, Macromolecules, 2003, 36, 7970; (c)
S. H. Hsiao, C. W. Chen and G. S. Liou, J. Polym. Sci., Part A:
Polym. Chem., 2004, 42, 3302; (d) I. Mustonen, T. Hukka and
T. Pakkanen, Macromol. Rapid Commun., 2000, 21, 1286; (e)
Z. Chen, Y. Liu, C. Zhang and F. Bai, J. Appl. Polym. Sci., 2004,
92, 2777.
17 (a) Polyimides, ed. D. Wilson, H. D. Stenzenberger and P. M.
Hergenrother, Blackie, Glasgow and London, 1990; (b) Polyimides:
Fundamentals and Applications, ed. M. K. Ghosh and K. L. Mittal,
Marcel Dekker, New York, 1996.
18 (a) F. W. Harris and S. L.-C. Hsu, High Perform. Polym., 1989, 1,
1; (b) Y. Imai, React. Funct. Polym., 1996, 30, 3; (c) S. H. Hsiao
and C. T. Li, Macromolecules, 1998, 31, 7213; (d) G. S. Liou,
J. Polym. Sci., Part A: Polym. Chem., 1998, 36, 1937; (e)
G. C. Eastmond, J. Paprotny and R. S. Irwin, Polymer, 1999, 40,
469; (f) G. C. Eastmond, M. Gibas and J. Paprotny, Eur. Polym. J.,
1999, 35, 2097; (g) D. S. Reddy, C. H. Chou, C. F. Shu and
G. H. Lee, Polymer, 2003, 44, 557; (h) B. Y. Myung, C. J. Ahn and
T. H. Yoon, Polymer, 2004, 45, 3185.
19 G. S. Liou, S. H. Hsiao, M. Ishida, M. Kakimoto and Y. Imai,
J. Polym. Sci., Part A: Polym. Chem., 2002, 40, 3815.
20 S. H. Cheng, S. H. Hsiao, T. H. Su and G. S. Liou,
Macromolecules, 2005, 38, 307.
21 E. T. Seo, R. F. Nelson, J. M. Fritsch, L. S. Marcoux, D. W. Leedy
and R. N. Adams, J. Am. Chem. Soc., 1966, 88, 3498.
22 L. Hagopian, G. Kohler and R. I. Walter, J. Phys. Chem., 1967, 71,
2290.
14 K. Kim, Y.-R. Hong, S.-W. Lee, J.-I. Jin, Y. Park, B.-H. Sohn,
W.-H. Kim and J.-K. Park, J. Mater. Chem., 2001, 11, 3023.
15 (a) Y. Zhang, T. Wada and H. Sasabe, J. Polym. Sci., Part A:
Polym. Chem., 1996, 34, 2289; (b) Q. Wang, A. Gharvi, W. Li and
L. Yu, Polym. Prepr., 1997, 38, 2, 516; (c) J. Jiang, C. Jiang,
W. Yang, H. Zhen, F. Hung and Y. Cao, Macromolecules, 2005,
38, 4072; (d) J. Huang, Y. Niu, W. Yang, Y. Mo, M. Yuan and
Y. Cao, Macromolecules, 2002, 35, 6080; (e) J.-F. Morin and
M. Leclerc, Macromolecules, 2001, 34, 4680.
23 A. Ito, H. Ino, K. Tanaka, K. Kanemoto and T. Kato, J. Org.
Chem., 2002, 67, 491.
24 H. Tachimori and T. Masuda, J. Polym. Sci., Part A: Polym.
Chem., 1995, 33, 2079.
25 J. P Chen and A. Natansohn, Macromolecules, 1999, 32, 3171.
26 J. N. Demas and G. A. Crosby, J. Phys. Chem., 1971, 75, 991.
27 T. Matsumoto and T. Kurosaki, Macromolecules, 1997, 30, 993.
1842 | J. Mater. Chem., 2006, 16, 1831–1842
This journal is ß The Royal Society of Chemistry 2006