Synthesis and characterization of photoactive poly(arylene ether sulfone)s containing azobenzene moieties in their main chains

Article abstract of DOI:10.1016/j.reactfunctpolym.2010.05.007

A series of azobenzene functionalized poly(arylene ether sulfone)s (azo-PAESs) has been synthesized via nucleophilic aromatic substitution polycondensation, and azobenzene chromophores could be introduced into the polymer main chains by copolymerization f

Full text of DOI:10.1016/j.reactfunctpolym.2010.05.007

Reactive & Functional Polymers 70 (2010) 616–621
Contents lists available at ScienceDirect
Reactive & Functional Polymers
journal homepage: www.elsevier.com/locate/react
Synthesis and characterization of photoactive poly(arylene ether sulfone)s
containing azobenzene moieties in their main chains
Xiangyu Jiang a, Xingbo Chen a,b, Xigui Yue a, Jingjing Zhang a, Shaowei Guan a, Haibo Zhang a,
,
*
Wenyi Zhang c, Qidai Chen c
a Alan G. MacDiarmid Institute, Jilin University, Changchun 130012, China
b State Key Lab for Ceramic Fibers Composites, National University of Defense Technology, Changsha, Hunan 410073, China
c State Key Lab on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of azobenzene functionalized poly(arylene ether sulfone)s (azo-PAESs) has been synthesized via
nucleophilic aromatic substitution polycondensation, and azobenzene chromophores could be intro-
duced into the polymer main chains by copolymerization from azo-monomers. These main chain type
azo-PAESs have high glass transition temperatures and good thermal stability. Exposed to an interference
pattern laser beam, spin-coated films of the azo-PAESs can form clear and stable surface relief gratings
(SRGs). These SRGs show increased thermal stabilities with the content of azo moieties and cannot be
fully removed until the temperature increases to 300 °C for azo-PAESs with a content of azo segments
above 50%.
Received 11 December 2009
Received in revised form 7 May 2010
Accepted 11 May 2010
Available online 16 May 2010
Keywords:
Azo-polymer
Poly(arylene ether sulfone)
Photoactive
Ó 2010 Elsevier Ltd. All rights reserved.
Surface relief grating
1. Introduction
ether sulfone)s have been widely studied as proton exchange
membranes, light emitting materials and optical materials [26–
Azobenzene is a well-known photoresponsive chromophore,
and its photoinduced and thermal isomerizations have been
extensively studied [1,2]. Polymers bearing azobenzene moieties
(azo-polymers) are fascinating materials and have attracted con-
siderable attention in recent years because of their unique revers-
ible photo-isomerization and photoinduced anisotropy properties
[3–8]. The photoinduced isomerization and anisotropy can cause
significant bulk, surface property variation and polarity of the poly-
mers, such as photoinduced phase transition, photoinduced
surface relief gratings (SRGs) and photoinduced birefringence
[9–15], which show potential applications in fields such as optical
data storage, optical switching and nonlinear optical materials
[16–23]. In order to increase the optical stability for long-term
applications, many efforts have been made to design and synthe-
size new high-Tg aromatic azo-polymers, such as polyacrylate con-
taining fully aromatic azo side chains and azo-polyimides. Their
optical properties show great thermal stability, which ensures
their applications as optical and electronic devices used in harsh
environments [24,25].
29]. We report herein the synthesis and characterization of novel
PAESs containing azobenzene chromophores in their main chains.
A detailed evaluation of their physical properties and the formation
of surface relief gratings are also reported.
2. Experimental
2.1. Materials
4,40-Diaminodiphenylsulfone (DDS, 99.5%), 4,40-dichlorodiphe-
nyl sulfone (DCDPS) and 4,40-isopropylidenediphenol (BPA, 99.5%)
were purchased from Shanghai Chemical Factory. Phenol was pur-
chased from Beijing Chemical Factory. Hydrochloric acid (37%),
ethanol (95%) and toluene (99.5%) were purchased from Beijing
Chemical Factory. Dimethyl sulfoxide (DMSO, 99.5%) and chloro-
form (99.5%) were purchased from Tianjin Chemical Factory. All or-
ganic solvents were obtained from commercial sources and used as
received. K2CO3 was dried at 120 °C for 24 h before being used for
polymerization.
Poly(arylene ether sulfone)s (PAESs) are a family of high-perfor-
mance engineering thermoplastics with excellent thermal,
mechanical and electrical properties. Functionalized poly(arylene
2.2. Measurements
Gel permeation chromatography (GPC) was carried out using a
Waters 410 instrument with N,N-dimethylformamide (DMF) as an
* Corresponding author. Tel./fax: +86 431 85168199.
E-mail address: zhanghaib@jlu.edu.cn (H. Zhang).
1381-5148/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.reactfunctpolym.2010.05.007

X. Jiang et al. / Reactive & Functional Polymers 70 (2010) 616–621
617
eluent and polystyrene as a calibration standard. Inherent viscosity
was determined on an Ubbelohde viscometer in a thermostatic
container with a polymer concentration of 0.5 g/dL in DMF at
25 °C. IR spectra (KBr pellet) were recorded on a Nicolet Impact
410 FTIR spectrophotometer. 1H NMR and 13C NMR spectra were
taken on a Bruker 510 (1H, 500 MHz; 13C, 125 MHz) instrument
using dimethylsulfoxide-d6 (DMSO-d6) as a solvent. Thermogravi-
metric analyses were performed on a PerkinElmer Pyris 1 TGA un-
der nitrogen and atmosphere (100 mL/min) at a heating rate of
10 °C/min. Glass transition temperatures (Tgs) were determined
by a DSC (Mettler Toledo DSC821e) instrument at a heating rate
of 20 °C/min under a nitrogen flow of 200 mL/min. The reported
Tg value was recorded from the second scan after the sample was
first heated and then quenched. UV–visible absorption spectra
were recorded on a UV2501-PC spectrophotometer at room tem-
perature. Optical microscope observation was performed on a Leica
DLMP with a Linkam THMSE 600 hot stage.
SRGs were optically inscribed on the polymers with linearly p-
polarized interfering laser beams. Polarized Nd:YAG nanosecond
pulsed laser beams (Spectra-Physics, Quanta-Ray-150, 355 nm),
with a pulse duration of 10 ns and repetition rate of 10 Hz, were
used as a recording light source. The spot of the laser beams is
10 mm in diameter, and the intensity of the recording laser con-
forms to a Gaussian distribution (about 60 mW/cm2). The surface
images of the surface relief gratings were monitored using atomic
force microscopy (AFM) in the tapping mode.
N2 inlet/outlet and a thermometer was charged with monomer
(0.9170 g, 0.002 mol), BPA (1.8263 g, 0.008 mol), DCDPS
1
(2.8778 g, 0.01 mol), anhydrous potassium carbonate (1.4504 g,
0.013 mol), 15 mL of DMSO and 15 mL of toluene. The reaction
mixture was allowed to reflux for 2 h under an N2 atmosphere.
The toluene was removed by distillation. The system was then
heated to 140 °C. The polymerization was allowed to react at
140–150 °C and stirred vigorously at this temperature until a very
viscous solution was obtained. Then the viscous solution was
slowly poured into water and stirred vigorously. The threadlike
polymer was pulverized into a powder after cooling. The powder
was washed with hot deionized water several times and reflux
treated in a Soxhlet extractor with ethanol. The resulting product
was dried at 100 °C under vacuum for 24 h, and 3.7 g of orange–
yellow solid was obtained; the yield was 82%. The copolymers
were prepared by varying the mole fractions of monomer 1 (m)
and BPA (n). Copolymers with the differing m/n ratios 0/10, 2/8,
5/5, and 10/0 were prepared and designated as 2a–c, and 2d,
respectively.
2.5. Polymer film preparation
Polymers were dissolved in cyclohexanone, and the solutions
(10% wt.) were filtered through syringe filters. Polymer films were
obtained by spin coating the polymer solution onto glass sub-
strates (which were subsequently cleaned in an ultrasonic bath
with DMF, THF, ethanol and distilled water). The thickness of the
2.3. Monomer synthesis
films was controlled to be approximately 1.0 lm by adjusting the
spinning rate for fabricating the SRGs. Residual solvent was re-
moved by heating the films in a vacuum oven at 100 °C for 2 days.
The films were stored in a desiccator for further studies.
2.3.1. Synthesis of 4,40-dihydroxyphenylazodiphenylsulfone (monomer
1, Scheme 1)
Monomer 1 was synthesized by diazotization reaction and fol-
lowed by coupling with phenol. Into a 1000 mL beaker equipped
with a mechanical stirrer, a dropping funnel, and a thermometer
were placed water (50 mL), ice (50 mL) and DDS (24.8 g, 0.1 mol).
Hydrochloric acid (0.8 mol, 67.2 mL) was added dropwise into
the stirred mixture through the dropping funnel. The solution
was cooled to 0–5 °C in an ice-water bath, and a concentrated
water solution of sodium nitrite (13.8 g, 0.2 mol) was added drop-
wise. The mixture was stirred for 30 min at 0–5 °C and yielded a
clear solution. The resulting solution was filtered and added drop-
wise into a solution of NaOH (8.0 g, 0.2 mol), phenol (18.8 g,
0.2 mol) and sodium bicarbonate (25.2 g, 0.3 mol) in 100 mL water.
The reaction mixture was stirred at 0–5 °C for approximately 2 h
and at room temperature for another 2 h. The final solution was
added slowly to 700 mL acid water (HCl), and a brown–orange pre-
cipitate of the azo compound was formed. The precipitate was col-
lected by filtration and washed thoroughly with water containing a
small amount of sodium hydrogen carbonate (pH = 8). The solid
was dried at 60 °C in a vacuum oven and finally recrystallized from
a mixture of THF/ethanol to obtain a pure orange–yellow powder
(Yield, 60%). m.p. ꢀ 288 °C (DSC); m/z (MALDI-TOF): 459 (M++H,
3. Results and discussion
3.1. Synthesis and characterization of monomer 1
We designed a bisphenol (monomer 1) containing azo groups,
and the reaction pathway for preparation of the monomer is illus-
trated in Scheme 1. The structure of monomer 1 was confirmed by
MS, IR, UV and 1H NMR. The IR spectrum exhibited characteristic
bands of –OH at 3393 cmꢁ1 and –SO2– at 1294 cmꢁ1. From the
UV–vis absorption spectra, we could see the characteristic absorp-
tion peak of
p ?
pꢂ electronic transitions for azo-aromatic
chromophores at 376 nm. In the 1H NMR spectra of monomer 1
(Fig. 1), all magnetic resonance signals were clearly assigned
according to the chemical shifts of hydrogen atoms. Due to the
strong electron attraction of sulfone and azo groups, signals of
C
24H18N4SO4 requires 458.10). m
max/cmꢁ1 3393 (AOH), 3048 (Ar–
H), 1294 (ASO2A); dH (500 MHz; DMSO, Me4Si): 10.54 (2H, s,
AOH), 8.17 (4H, d, J = 8.6 Hz, ArH), 7.98 (4H, d, J = 8.6 Hz, ArH),
7.86 (4H, d, J = 8.9 Hz, ArH), 6.96 (d, 4H, J = 8.9 Hz, ArH); dc
(125 MHz; DMSO, Me4Si):162.57, 155.41, 145.80, 141.81, 129.33,
126.06, 123.50, 116.75; Calculated C, 62.87; H, 3.96; N, 12.12; O,
13.96; Found C, 63.05; H, 3.77; N, 12.35; O, 13.77.
2.4. Polymer synthesis, 2a–d
2.4.1. Synthesis of azo-PAESs
The synthetic procedure of azo-PAES copolymers was as fol-
lows. For 2b, a dry 75 mL three-necked flask equipped with a
mechanical stirrer, a Dean–Stark trap, a cold water condenser, an
Fig. 1. 1H NMR spectrum of monomer 1.

618
X. Jiang et al. / Reactive & Functional Polymers 70 (2010) 616–621
requirement of the current study. The obtained azo-polymers with
low azo content (2b) show similar solubility with polysulfone (2a)
and can dissolve in dichloromethane, chloroform, cyclohexanone,
DMF and DMSO. However, those polymers with high azo content
(2c and 2d) are only soluble in polar aprotic solvents such as cyclo-
hexanone, DMF and DMSO.
The chemical structures of azo-PAESs were confirmed by IR, 1H
NMR and UV–vis spectra. In the IR spectra of azo-PAESs (Fig. 2), the
absorption bands at 2969 and 1235 cmꢁ1 are attributed to the
stretching vibrations of the methyl (–CH3) and the aromatic ether
group (Ar–O–Ar), respectively. With the increase of azo content,
the intensities of –CH3 is obviously decreased. Fig. 3 shows typical
1H NMR spectra of 2b and 2c in DMSO-d6 with signal assignments.
Although 1H NMR spectra of 2b and 2c were complicated and
greatly overlapped, which made them difficult to analyze, the sig-
nals corresponding to the hydrogens of –CH3 (d, 1.68 ppm) and the
hydrogens located at ortho-position of sulfone groups in –N = N–
Ph–SO2–Ph–N = N– segments (d, 8.17 ppm) were well distin-
guished from other hydrogens. From the ration between them,
we can calculate the exact azo-content in the obtained copolymers.
The calculated results are in good agreement with the expected
values from the azo-monomer feed ratio, indicating that the azo
content in the copolymer can be well controlled. UV–vis spectra
of azo-PAESs in DMF solution are shown in Fig. 4. From the spectra
of azo-PAESs (2b–d), we can see the characteristic absorption peak
of azo-aromatic chromophores at approximately 359 nm. Com-
pared with monomer 1, the absorption of azo-PAESs shows a slight
blue shift because the hydroxyl groups in monomer 1 have been
changed to ether groups during copolymerization, indicating suc-
cessful introduction of azo moieties into the polymer chains.
Scheme 1. Synthesis route of monomer 1.
hydrogens 1–3 appear at the low field region with a chemical shift
about 8.0 ppm. The signal of hydrogen 4 appears at 7.0 ppm be-
cause of the existence of the hydroxyl group, a strong electron do-
nor. The signal at 10.54 ppm is assigned to the hydrogen of the
hydroxyl group.
3.2. Polymer synthesis and structure characterization
The azo-PAESs were synthesized through typical nucleophilic
substitution polycondensation reactions from the corresponding
bis(4-chlorophenyl)sulfone and bisphenol monomers, as shown
in Scheme 2. The polymerization was carried out in DMSO with
potassium carbonate as a base catalyst and toluene for dehydra-
tion. Herein, we prepared four kinds of polymers with azo segment
contents of 0% (2a), 20% (2b), 50% (2c) and 100% (2d). As shown in
Table 1, the inherent viscosities of the resulting polymers were
0.15–0.24 dL/g in DMF at 25 °C, and the number-average molecular
weights (Mn) were in the range of 0.8 ꢃ 104–1.8 ꢃ 104 with a distri-
bution of 2.1–2.9 (measured by GPC). Under the same reaction con-
ditions, the Mn values of these copolymers decreased with
increasing azo content. There are two factors that may be associ-
ated with this result. One is the lower reactivity of the azoben-
zene-containing monomer due to its bulky rigid structure. The
other is that the copolymers with high azo content show high
apparent viscosity quickly in the reaction system, which impedes
the polymerization reaction. However, the Mn values of most poly-
mers obtained could reach above 1 ꢃ 104, which satisfies the
3.3. Thermal properties of azo-PAESs
The thermal stabilities of azo-PAESs were investigated by ther-
mogravimetric analysis (TGA) at a heating rate of 10 °C/min under
a nitrogen atmosphere. Fig. 5 shows the TGA curves of the azo-
Scheme 2. Synthesis route of azo-PAESs 2a–d.
Table 1
Inherent viscosities and properties of azo-PAESs.
a
b
Polymer
giv (dL/g)
Tg (°C)
Td5 (°C)c
Td10 (°C)d
Y (%)e
Mn
Mn/Mw
2a
2b
2c
2d
0.24
0.16
0.15
0.17
183
187
195
198
492
418
389
386
506
457
408
395
36
42
47
52
1.8 ꢃ 104
1.2 ꢃ 104
1.1 ꢃ 104
0.8 ꢃ 104
2.3
2.9
2.6
2.1
a
b
c
Inherent viscosity was determined on an Ubbelohde viscometer in a thermostatic container with a polymer concentration of 0.5 g/dL in DMF at 25 °C.
Glass transition temperature by DSC.
5% weight-loss temperatures were detected at a heating rate of 10 °C/min in nitrogen with a gas flow of 100 mL/min.
10% weight-loss temperatures were detected at a heating rate of 10 °C/min in nitrogen with a gas flow of 100 mL/min.
Material that remains in the crucible at 700 °C.
d
e

X. Jiang et al. / Reactive & Functional Polymers 70 (2010) 616–621
619
Fig. 5. TGA curves of azo-PAESs 2a–d in nitrogen atmosphere.
Fig. 2. IR spectra of azo-PAESs 2a–d.
Fig. 6. DSC curves of azo-PAESs 2a–d.
mal decomposition of the main chains of azo-PAESs. The thermal
stability decreases as the content of azo moieties increases. In con-
trast, the remains in the crucible at 700 °C were increased from
36% to 52% with increasing azobenzene content from 0% to 100%
due to good flame-retardant characteristics associated with these
azo-polymers [1]. The 5% and 10% weight-loss temperatures of
azo-PAES 2b–d were all above 380 °C, indicating good thermal
stabilities.
Fig. 3. 1H NMR spectra of azo-PAESs 2b and c in DMSO-d6.
Tgs of azo-PAESs were determined by differential scanning cal-
orimetry (DSC). The resulting Tg values of the polymers are listed in
Table 1. In the curves (Fig. 6), the polymers 2a–d show the second-
order phase transition and no other thermal changes except that
glass transitions are observed, indicating the amorphous nature
of azo-PAESs. Due to the aromatic structure and the rigid azoben-
zene chromophores in the polymer main chains, azo-PAESs show
high glass transition temperatures (Tgs), and the Tg value increases
from 183 °C to 198 °C with increasing azo content.
3.4. Photo-isomerization behavior of azo-PAESs
The UV–vis absorption spectrum of 2b in DMF solution exhib-
ited two absorption bands centered around 362 nm and 452 nm
in the range of 280–650 nm, corresponding to
Fig. 4. Uv spectra of azo-PAESs 2a–d in DMF solution at room temperature.
p ?
pꢂ and n ? pꢂ
electronic transitions of azo-aromatic chromophores, respectively.
When the solution was irradiated by 360 nm light (Fig. 7a), azo-
benzene chromophores underwent a trans-to-cis photo-isomeriza-
tion process. The absorption band at 362 nm gradually decreased,
and the absorption band at 452 nm gradually increased, with pro-
longed irradiation time.
PAESs, and the experimental data are listed in Table 1. Table 1
shows that all azo-HPAEs containing azobenzene moieties exhibit
two degradation steps. The first weight-loss between 370 °C and
470 °C is attributed to the thermal degradation of azobenzene moi-
eties, and the second weight-loss above 470 °C represents the ther-

620
X. Jiang et al. / Reactive & Functional Polymers 70 (2010) 616–621
Fig. 7. UV–vis absorption spectra of 2b in DMF solution at 25 °C (a) with a different irradiation time under 360 nm light irradiation and (b) with a different irradiation time
under visible light.
On the other hand, when the irradiated sample was annealed at
a certain temperature or irradiated with visible light, the absorp-
tion peak at 362 nm gradually recovered to the starting value
(Fig. 7b), confirming the reversibility of the photo-isomerization
process. This result clearly indicates homogeneous photo-isomeri-
zation behavior for trans- and cis-azobenzene chromophores in the
polymer sample. The azo-polymers 2c and 2d also showed the
same reversibility of the photo-isomerization process.
tern. In addition, the modulation depth could be precisely well ad-
justed by the irradiation time and the irradiation energy. The
spatial period (
two interfering beams and the wavelength k of the writing beams
by Bragg’s law: k = 2 sin h [3,10]. Here, the experimental spatial
K) depended on both the angle h between the
K
period is in good agreement with the theoretical value calculated
from the above equation, which further confirms that the spatial
period can be well controlled by setting the value of h.
3.5. Preparation and characterization of SRGs of 2b
3.6. Thermal stability of the SRGs
Formation of photoinduced SRGs was one of the most interest-
ing properties of azo-polymers in recent years [3–5,30–33]. By
exposure of the polymer film to the interfering laser beams, SRGs
are formed on the film at a temperature well below its Tg value.
This function could be potentially applied to holographic memo-
ries, reversible optical data storage and waveguide couplers.
Spin-coated films of azo-PAESs were used to carry out SRG
inscription experiments. The films were subsequently exposed to
two polarized interfering laser beams of equal intensity (30 mW/
cm2) for 30 s with the angle h between them set to 6.4°. Fig. 8
shows the microscope images, typical AFM plane and three-dimen-
sional images of the surface structure of 2b. AFM observation indi-
cated that sinusoidal surface relief structures with regular spaces
were fabricated on the film surface of 2b. AFM section analysis
shows that the surface modulation depth is about 110 nm, and
Another important requirement of SRGs is their shape stability
in terms of long-term storage and durability at high temperatures
[4,22,31]. In order to test whether the surface relief grating based
on such azo-polymers can withstand high temperatures, we used
temperature-dependent AFM to investigate changes in the surface
profiles with increasing temperature of the substrate. Fig. 9 shows
the AFM images of surface relief gratings for 2b at high tempera-
tures. We found that the surface modulation depth at 100 °C is
similar to that observed at room temperature, as indicated by
AFM section analysis. When the temperature increased to 150 °C,
the surface modulation depth decreased from 130 nm to 64 nm,
however, the SRGs on the 2b film were still clear and kept a good
shape. We also observed changes in the surface profiles of the films
from 25 °C to 300 °C at a heating rate of 10 °C/min using an optical
microscope with a Linkam THMS 600 hot stage. Surface relief grat-
ings on the 2b film became blurry when they were heated to 180 °C
the grating spacing is about 1.6 lm, as set by the interference pat-
Fig. 8. Images of typical SRGs formed on 2b film. (a) Microscope image of SRGs (600ꢃ); (b) AFM plane view of the SRGs (10 ꢃ 10
SRGs (10 ꢃ 10
m2).
l
m2) and (c) typical AFM 3-D view of the
l

X. Jiang et al. / Reactive & Functional Polymers 70 (2010) 616–621
621
Fig. 9. AFM images showing the surface profiles change of SRGs formed on 2b film at various temperatures: (a) 25 °C, (b) 50 °C, (c) 100 °C, and (d) 150 °C (the image size is
10 ꢃ 10
m2 in each case, and each image was recorded in the height mode).
l
[9] D.Y. Kim, S.K. Tripathy, L. Li, J. Kumar, Appl. Phys. Lett. 66 (1995) 1166–1168.
[10] P. Che, Y. He, X. Wang, Macromolecules 38 (2005) 8657–8663.
[11] P. Rochon, E. Batalla, A. Natansohn, Appl. Phys. Lett. 66 (1995) 136–138.
[12] Y. Wu, A. Natansohn, P. Rochon, Macromolecules 37 (2004) 6090–6095.
[13] A. Natansohn, P. Rochon, C. Barrett, A. Hay, Chem. Mater. 7 (1995) 1612–1615.
[14] S. Cha, D. Choi, D. Oh, D. Han, C. Lee, J. Jin, Adv. Funct. Mater. 12 (2002) 670–
678.
[15] M. Jin, Q. Yang, R. Lu, T. Xu, Y. Zhao, J. Polym. Sci. Part A: Polym. Chem. 42
(2004) 4237–4247.
[16] K. Yager, C. Barrett, J. Photochem. Photobiol. A 182 (2006) 250–261.
[17] P. Aruna, B.S. Rao, React. Funct. Polym. 69 (2009) 20–26.
[18] R. Fernandez, I. Mondragon, P. Oyanguren, M. Galante, React. Funct. Polym. 68
(2008) 70–76.
and then evidently disappeared at 205 °C. Furthermore, for the
polymer film containing a higher content of azobenzene moieties,
such as the polymer 2c film with a 50% azo segment content, the
SRGs formed on it showed higher stability than those on 2b (20%
azo segment content). The induced SRGs on 2c films kept a good
shape at 260 °C and could not be totally erased by heating even
to 300 °C.
4. Conclusions
[19] T. Fukuda, J. Kim, D. Barada, K. Yase, J. Photochem. Photobiol. A 183 (2006)
273–279.
[20] Z. Li, A. Qin, J. Lam, Y. Dong, C. Ye, I. Williams, B. Tang, Macromolecules 39
(2006) 1436–1442.
[21] Y. Wu, A. Natansohn, P. Rochon, Macromolecules 34 (2001) 7822–7828.
[22] N. Zettsu, T. Ubukata, T. Seki, K. Ichimura, Adv. Mater. 13 (2001) 1693–1697.
[23] Y. Zhang, W. Zhang, X. Chen, Z. Cheng, J. Wu, J. Zhu, X. Zhu, J. Polym. Sci. Part A:
Polym. Chem. 46 (2008) 777–789.
[24] J. Chen, F. Labarthet, A. Natansohn, P. Rochon, Macromolecules 32 (1999)
8572–8579.
Poly(aryl ether sulfone)s containing azobenzene chromophores
in their main chains have been synthesized via a nucleophilic aro-
matic substitution polycondensation. The obtained azo-PAESs have
high glass transition temperatures (Tg > 183 °C) and good thermal
stability (Td5 > 386 °C). By exposing the spin-coated films to an
interference pattern laser beam, the azo-PAESs were used for fab-
rication of surface relief gratings. The SRGs have excellent thermal
stability and can keep a good shape below 260 °C.
[25] H. Li, R. Termine, L. Angiolini, L. Giorgini, F. Mauriello, A. Golemme, Chem.
Mater. 21 (2009) 2403–2409.
[26] H.B. Zhang, J.H. Pang, D. Wang, X. Li, Z.H. Jiang, J. Membr. Sci. 264 (2005) 56–
64.
References
[27] Z. Lu, P. Shao, J. Li, J. Hua, J.G. Qin, A. Qin, C. Ye, Macromolecules 37 (2004)
7089–7096.
[28] W. Wan, Y. Meng, Q. Zhu, S. Tiong, A. Hay, Polymer 44 (2003) 575–582.
[29] X.B. Chen, J.J. Zhang, H.B. Zhang, Z.H. Jiang, G. Shi, Y.L. Song, Dyes Pigm. 77
(2008) 223–228.
[30] C. Chun, M. Kim, D. Vak, D. Kim, J. Mater. Chem. 13 (2003) 2904–2909.
[31] T. Fukuda, H. Shiraga, T. Kimura, M. Viswanathan, J. Kumar, S. Tripathy,
Macromolecules 33 (2000) 4220–4225.
[32] E. Ishow, B. Lebon, Y. He, X. Wang, L. Bouteiller, L. Galmiche, K. Nakatani, Chem.
Mater. 18 (2006) 1261–1267.
[1] A. Bhatnagar, J. Mueller, D. Osborn, T. Martin, J. Wirtz, D. Mohanty, Polymer 36
(1995) 3019–3025.
[2] A. Izumi, M. Teraguchi, R. Nomura, T. Masuda, Macromolecules 33 (2000)
5347–5352.
[3] A. Natansohn, P. Rochon, Chem. Rev. 102 (2002) 4139–4175.
[4] H. Nakano, T. Tanino, T. Takahashi, H. Ando, Y. Shirota, J. Mater. Chem. 18
(2008) 242–246.
[5] I. Sava, A. Resmerita, G. Lisa, V. Damian, N. Hurduc, Polymer 49 (2008) 1475–
1482.
[6] K. Okano, A. Shishido, T. Ikeda, Adv. Mater. 18 (2006) 523–527.
[7] B. Lachut, S. Maier, H. Atwater, M. Dood, A. Polman, R. Hagen, S. Kostromine,
Adv. Mater. 16 (2004) 1746–1750.
[33] J. Gao, Y.N. He, H.P. Xu, B. Song, X. Zhang, Z.Q. Wang, X.G. Wang, Chem. Mater.
19 (2007) 14–17.
[8] Y. Yu, T. Ikeda, Angew. Chem. Int. Ed. 45 (2006) 5416–5418.