The use of novel biodegradable, optically active and nanostructured poly(amide-ester-imide) as a polymer matrix for preparation of modified ZnO based bionanocomposites

Article abstract of DOI:10.1016/j.materresbull.2012.02.015

A novel biodegradable and nanostructured poly(amide-ester-imide) (PAEI) based on two different amino acids, was synthesized via direct polycondensation of biodegradable N,N′-bis[2-(methyl-3-(4-hydroxyphenyl)propanoate)] isophthaldiamide and N,N′-(pyromellitoyl)-bis-l-phenylalanine diacid. The resulting polymer was characterized by FT-IR, ¹H NMR, specific rotation, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. The synthesized polymer showed good thermal stability with nano and sphere structure. Then PAEI/ZnO bionanocomposites (BNCs) were fabricated via interaction of pure PAEI and ZnO nanoparticles. The surface of ZnO was modified with two different silane coupling agents. PAEI/ZnO BNCs were studied and characterized by FT-IR, XRD, UV/vis, FE-SEM and TEM. The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAEI matrix on nanoscale. Furthermore the effect of ZnO nanoparticle on the thermal stability of the polymer was investigated with TGA and DSC technique.

Full text of DOI:10.1016/j.materresbull.2012.02.015

Materials Research Bulletin 47 (2012) 1123–1129
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Materials Research Bulletin
journal homepage: www.elsevier.com/locate/matresbu
The use of novel biodegradable, optically active and nanostructured
poly(amide-ester-imide) as a polymer matrix for preparation of
modified ZnO based bionanocomposites
a
Amir Abdolmaleki a,c, , Shadpour Mallakpour
*
b,c,**
, Sedigheh Borandeh
a Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran
b Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran
c Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
A novel biodegradable and nanostructured poly(amide-ester-imide) (PAEI) based on two different amino
acids, was synthesized via direct polycondensation of biodegradable N,N0-bis[2-(methyl-3-(4-hydro-
Received 20 November 2011
Received in revised form 12 January 2012
Accepted 14 February 2012
Available online 22 February 2012
xyphenyl)propanoate)]isophthaldiamide and N,N0-(pyromellitoyl)-bis-
L-phenylalanine diacid. The
resulting polymer was characterized by FT-IR, 1H NMR, specific rotation, elemental analysis,
thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD)
and field emission scanning electron microscopy (FE-SEM) analysis. The synthesized polymer showed
good thermal stability with nano and sphere structure. Then PAEI/ZnO bionanocomposites (BNCs) were
fabricated via interaction of pure PAEI and ZnO nanoparticles. The surface of ZnO was modified with two
different silane coupling agents. PAEI/ZnO BNCs were studied and characterized by FT-IR, XRD, UV/vis,
FE-SEM and TEM. The TEM and FE-SEM results indicated that the nanoparticles were dispersed
homogeneously in PAEI matrix on nanoscale. Furthermore the effect of ZnO nanoparticle on the thermal
stability of the polymer was investigated with TGA and DSC technique.
Keywords:
A. Nanostructures
A. Composites
C. Electron microscopy
C. Differential scanning calorimetry (DSC)
C. Thermogravimetric analysis (TGA)
ß 2012 Elsevier Ltd. All rights reserved.
1. Introduction
Nanoparticles can be directly added into organic polymers;
however, their advantages have been limited due to their
Controlled patterning of materials at the nanoscale is the bases
for nanotechnological manufacturing. Recently, several nanostruc-
tured polymers have been fabricated for an extensive range of
potential applications [1,2]. The development of nanostructured
polymers has made widely essential and practical frontiers, which
has attracted excellent attention in the last decades [3]. Further-
more, with the expansion of nanotechnology, nanoparticles have
been increasingly applied to organic polymers. These polymeric
nanocomposites, in which polymers provide as hosts for inorganic
nanoparticles, have attracted scientific and technological interest
due to their relatively remarkable various properties including
mechanical properties, such as scratching and abrasion resistance,
optical properties, and wide-spread potential applications [4–10].
aggregation and incompatibility with organic polymers. Conse-
quently, nanoparticles require some modification to turn their
surface from hydrophilic to organophilic [11,12]. Nanoparticle
modifications have done with different compounds like, surface-
active agent, coupling agent, fatty acid and alcohol [13–16].
Nowadays, great interest attracted to nanocomposite based on
biopolymers due to their similarity to natural materials [17,18].
Polymers containing amino acids are great candidate for preparing
of nanocomposites, because they are biodegradable and biocom-
patible in the biological environment [19–22] and also can
chemically bind with inorganic components of composite materials
and consequently stabilize the dispersed additives at a nanoscale
level [23,24]. In addition, some of the nanoparticles like ZnO, due to
their biological properties like antimicrobial activities, causing
biomedical applications for nanocomposites based on them [25,26].
In this investigation, a novel optically active, biodegradable and
nanostructured poly(amide-ester-imide) (PAEI) with good thermal
stability, was prepared, via direct polycondensation of optically
* Corresponding author at: Department of Chemistry, Isfahan University of
Technology, Isfahan 84156-83111, Islamic Republic of Iran. Tel.: +98 3113912351;
fax: +98 3113912350.
** Corresponding author at: Organic Polymer Chemistry Research Laboratory,
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111,
Islamic Republic of Iran. Tel.: +98 3113913267; fax: +98 3113912350.
E-mail addresses: abdolmaleki@cc.iut.ac.ir, amirabdolmaleki@yahoo.com
(A. Abdolmaleki), mallak@cc.iut.ac.ir, mallak777@yahoo.com,
mallakpour84@alumni.ufl.edu (S. Mallakpour).
active
L-phenyl aniline based diacid and an optically active
S-tyrosine based diol using TsCl/DMF/Py as a condensing agent.
Then, poly(amide-ester-imide)/zinc oxide (PAEI/ZnO) bionano-
composites (BNCs) were synthesized under ultrasonic irradiation.
The ZnO nanoparticles were functionalized with two different
0025-5408/$ – see front matter ß 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.materresbull.2012.02.015

1124
A. Abdolmaleki et al. / Materials Research Bulletin 47 (2012) 1123–1129
silane coupling agents for homogeneous dispersing in polymer
matrix. The resulting BNCs were characterized by a variety of
techniques including FT-IR, XRD, TGA, DSC, UV/vis and their
morphology were investigated by FE-SEM and TEM analyses.
Thermal properties of the polymer and PAEI/ZnO BNCs were studied
on STA503 win TA instrument in nitrogen atmosphere at a heating
rate of 10 8C/min. Differential scanning calorimetry (DSC) analysis
was taken by Perkin-Elmer DSC-7 in nitrogen atmosphere at a
heating rate of 10 8C/min. The morphology of the synthesized
polymer and BNCs was observed using field emission scanning
electron microscopy (FE-SEM). FE-SEM micrographs of samples
were taken on a Hitachi (S-4160). The morphology and dispersity
analysis was performed on transmission electron micrograph (TEM)
analyzer on Philips CM 120 operating at 100 kV.
2. Experimental
2.1. Materials
S-Tyrosine,
L-phenyl aniline, isophthaloyl dichloride,
g-metha-
cryloxypropyltrimethoxy silane, KH570 and
g
-aminopropyl-
triethoxy silane, KH550 were purchased from Merck Chemical
Co. N-Methyl-2-pyrrolidinon (NMP, Merck Chemical Co.), N,N-
dimethyl formamide (DMF, Merck Chemical Co.) and triethylamine
(TEA, Merck Chemical Co.) were dried over BaO and then were
2.4. Diol synthesis
N,N0-Bis[2-(methyl-3-(4-hydroxyphenyl)propanoate)]i-
sophthaldiamide (5) was synthesized via the reaction of S-tyrosine
methyl ester (3) [27] (1.07 g, 5.5 mmol) and isophthaloyl
dichloride (4) (0.5 g, 2.5 mmol) in 6 mL of NMP as a solvent at
ꢁ20 8C (Scheme 1) [21].
˚
distilled under reduced pressure and stored over 4 A molecular
sieves. ZnO nanoparticle with an average particle size of about 25–
30 nm was purchased from Neutrino Co. Other reagents and
solvents were obtained commercially and used as received.
2.5. Diacid synthesis
2.2. Apparatus
N,N0-(Pyromellitoyl)-bis-
L-phenylalanine diacid (9) was pre-
A horn probe MISONIX ultrasonic liquid processor, XL-2000
SERIES with frequency 2.25 ꢀ 104 Hz and power 100 W was used
in solution mixture.
pared according to our previous works [28] and is shown in
Scheme 2.
2.6. Polymer synthesis
2.3. Characterization methods
The PAEI was prepared by the following procedure (Scheme 3):
a solution of pyridine (Py) (0.4 mL; 5 mmol) with p-toluene-
sulfonyl chloride (TsCl) (0.372 g; 1.95 mmol) after 30 min
stirring at room temperature, was treated with DMF (0.18 mL;
2.44 mmol) for 30 min and the mixture was added dropwise to a
solution of diacid (9) (0.20 g; 0.39 mmol) in Py (0.4 mL). The
mixture was maintained at room temperature for 30 min and
then diol (5) (0.20 g; 0.39 mmol) was added and the whole
solution was stirred at room temperature for 30 min and then at
120 8C for 6 h. The viscous liquid was precipitated in 50 mL of
methanol/water mixture, filtered off, and washed with metha-
nol/water solution mixture. Powdered polymer was dried at
80 8C for 12 h under vacuum to leave 0.264 g (68%) of cream
PAEI.
The chemical composition of the intermediates and obtained
particles was studied by FT-IR spectroscopy using a Jasco-680 FT-IR
spectrophotometer in the spectral range between 4000 and
400 cmꢁ1 with KBr pellet. Vibration bands were reported as wave
number (cmꢁ1). The band intensities are assigned as weak (w),
medium (m), shoulder (sh), strong (s), and broad (br). The 1H NMR
spectrum was recorded on Bruker Advance 500 MHz spectrometer
operating on monomers and polymer solution in DMSO-d6.
Chemical shifts are given in the
d scale in parts per million (ppm).
Proton resonances are designated as singlet (s), broad doublet (bd),
broad triplet (bt) and multiplet (m). Elemental analyses were
performed with a CHNS-932, Leco. Inherent viscosities of polymer
solution (0.5%, w/v) in NMP were determined at 25 8C by a standard
procedure using a Cannon-Fenske routine viscometer. The specific
rotations were measured by a Jasco polarimeter. X-ray diffraction
studies of the samples were carried out by Bruker, D8ADVANCE with
½
a 2D5
ꢂ
¼ ꢁ8:76ꢃ (c = 0.5 g/dL, NMP); FT-IR (KBr, cmꢁ1):
n = 3374
(m, br), 1771 (w), 1721 (s), 1649 (m), 1515 (m, sh), 1444 (w), 1385
(m), 1362 (m), 1221 (m), 1106 (m), 828 (w), 727 (m), 700 (m), 491
a scanning rate of 0.028/min with Cu K
a
radiation operating at 45 kV
(w); 1H NMR (500 MHz, DMSO-d6, ppm):
d = 2.95 (m, 4H), 3.28 (m,
and 100 mA within a scan range of 2 = 10–808. UV/vis spectra of the
u
4H), 3.57 (s, 6H), 4.62 (m, 2H, chiral center), 4.53 (m, 2H, chiral
center), 6.59 (bt, 2H), 6.96 (bd, 4H), 7.02–7.08 (bt, 4H), 7.12 (bd,
4H), 7.29 (bd, 4H), 7.49–7.50 (bt, 1H), 7.87 (bd, 2H), 8.11 (s, 1H),
8.18 (s, 2H) and 8.97 (NH, s, 2H). Elemental analysis for
polymer and PAEI/ZnO BNCs were measured on UV/Vis/NIR
spectrophotometer, JASCO, V-570 with solid pellets sample of
polymer and BNCs in the spectral range between 200 and 800 nm.
HO
HO
SOCl 2 / MeOH
-10 ºC
HO
H2N
H
ClH3N
H2N
H
H
NEt3/ CH2Cl2
0 ºC
OH
O
OCH3
OCH3
*
*
*
O
O
O
1
2
3
OCH3
H
HO
OH
H3CO
H
O
O
O
O
O
NMP/ TEA
Cl
Cl
3
+
NH
NH
*
*
-20 ºC
4
5
Scheme 1. Synthesis of diol 5.

A. Abdolmaleki et al. / Materials Research Bulletin 47 (2012) 1123–1129
1125
O
O
O
O
O
PhH2C
H
PhH2C
HOOC
H
H2N
COOH
H
CH3COOH
*
COOH
N
N
H
*
+
O
O
*
H
PhH2C
R.T
HO
OH
O
O
O
7
6
8
O
O
N
Reflux
HOOC
PhH2C
N
COOH
CH2Ph
*
*
H
H
O
O
Scheme 2. Synthesis of diacid 9.
+
5
9
TsCl/ Py/ DMF
O
O
H
CH2P
H
PhH2C
O
h
OCH3
O
H3CO
H
*
O
H
*
O
N
N
O
O
n
O
O
*
*
NH
NH
O
O
10
Scheme 3. Direct polycondensation of diol 5 with diacid 9.
(C56H44N4O14): Calcd: C, 67.46%; H, 4.45%; N, 5.62%. Found: C,
66.35%; H, 4.51%; N, 5.58%.
synthesized by direct polycondensation of an equimolar mixture
of diol (5) with diacid (9) using TsCl/DMF/Py as a condensing agent
(Scheme 3). The inherent viscosity of the resulting polymer was
0.39 dL/g and the yield was 68%. Because of the existence of amino
acid in the polymer’s backbone, this polymer is optically active and
2.7. Surface modification of ZnO nanoparticles
ZnO nanoparticles were preheated at 110 8C in a vacuum oven
for 24 h to remove absorbed moisture and then were used for
preparation of bionanocomposite. ZnO nanoparticles (0.2 g) were
added into absolute ethanol (10 mL) and were ultrasonicated for
15 min. Then, KH570 or KH550 (20 wt% ZnO) was added to the
dispersed solution, and the mixture of nanoparticles and silane
coupling agents was irradiated under ultrasonic radiation for
30 min. The suspension was filtrated and washed with ethanol to
remove unreacted KH570 or KH550 and the obtained solid was
dried at 60 8C for more than 24 h.
its specific rotation is ½a D25
ꢂ
¼ ꢁ8:76ꢃ (c = 0.5 g/dL, NMP).
The structure of synthesized polymer was confirmed by FT-IR,
1H NMR spectroscopy and elemental analysis.
2.8. Preparation of PAEI/ZnO BNCs
The preparation of PAEI/ZnO BNCs was carried out by the
following procedure: different amounts of modified ZnO nanopar-
ticles (6, 8 and 10 wt%) weremixedwithPAEI(0.1 g)and themixture
was dispersed in 20 mL of absolute ethanol and then was irradiated
under ultrasound waves for 4 h. The solvent was removed and the
obtained solid was dried in vacuum at 80 8C for 4 h.
3. Results and discussion
3.1. Polymer synthesis
The optically active diol (5) and diacid (9) were synthesized
according to the reported procedures [21,28]. PAEI 10 was
Fig. 1. FT-IR spectra of: (a) diacid 9, (b) diol 5 and (c) PAEI.

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A. Abdolmaleki et al. / Materials Research Bulletin 47 (2012) 1123–1129
Fig. 3. TGA thermogram of PAEI.
to these data the synthesized polymer is thermally stable that is
due to the existence of aromatic structure in the polymer’s
backbones which increases the stability of the polymer toward
heating.
Fig. 2. 1H NMR spectrum of PAEI.
In addition, the thermal properties of the synthesized polymer
were calculated via DSC measurement with a heating rate of
10 8C/min under nitrogen atmosphere. According to the obtained
result, the glass transition temperature (Tg) of this polymer was
178 8C.
3.1.1. FT-IR analysis
The FT-IR spectrum of polymer (Fig. 1c) showed absorptions
around 3374 cmꢁ1 (N–H), and three carbonyl (imide, ester and
amide’s C55O) absorptions at 1771, 1721 and 1649 cmꢁ1
,
respectively. Absorptions at 1385 and 727 cmꢁ1 indicated the
presence of the imide heterocycle in the polymer construction.
3.1.4. Field emission scanning electron microscopy (FE-SEM)
The morphology of PAEI was studied via FE-SEM analysis.
According to these micrographs (Fig. 4), the polymer consists of
nano and sphere structure.
3.1.2. 1H NMR study
The 1H NMR spectrum confirmed the structure of synthesized
polymer (Fig. 2). The two different protons of chiral centers
appeared at 4.62 and 4.53 ppm that is due to the existence of two
kinds of amino acid in the PAEI structure. The peaks between 6.59
and 8.11 ppm were assigned to aromatic protons and the peak at
8.18 ppm was assigned to pyromellitimide ring protons. The N–H
proton of amide groups appeared at 8.97 ppm.
3.2. Bionanocomposites synthesis and characterization
At first, to improve the dispersion of nanoparticles and increasing
possible interactions between nanoparticles and polymer matrix,
the surface of the ZnO nanoparticles were modified with
g-
According to our previous works, diol (5) and diacid (9) are
biologically active and biodegradable in soil environment [21,29],
therefore the synthesized PAEI is expected to be biodegradable and
could be classified under environmentally friendly polymers.
methacryloxypropyltrimethoxy silane, KH570 and -aminopropyl-
g
triethoxy silane, KH550. The hydroxyl groups of ZnO were replaced
with OCH3 of the KH570 or OCH2CH3 of the KH550 to bond to its
surface [11,30]. In functionalized ZnO, the organic chains of KH570
and KH550 can fulfill steric hindrance between inorganic nano-
particles and prevent their aggregation. Then, PAEI/ZnO BNCs were
fabricated by adding various ZnO contents to the PAEI/EtOH
suspension under ultrasound irradiation.
3.1.3. Thermal properties (TGA and DSC analysis)
The thermal properties of PAEI were evaluated by TGA in a
nitrogen atmosphere at a heating rate of 10 8C/min (Fig. 3). The
temperature of 5% and 10% weight loss with char yield at 800 8C
have been calculated from thermograms, and used to evaluate the
thermal stability of the polymer. The 5 and 10% weight loss
temperatures of the PAEI are 279 and 298 8C, respectively. The char
yield of this polymer in N2 atmosphere is 27% at 800 8C. According
3.2.1. FT-IR study
Figs. 5 and 6 show the FT-IR spectra of pure PAEI, modified ZnO
with two different coupling agents and bionanocomposites.
The spectra of the novel BNCs with different ZnO-KH570 and
Fig. 4. FE-SEM micrographs of pure PAEI.

A. Abdolmaleki et al. / Materials Research Bulletin 47 (2012) 1123–1129
1127
Fig. 7. XRD spectra of: (a) ZnO, (b) PAEI/ZnO-KH550 (10 wt%), (c) PAEI/ZnO-KH570
(10 wt%) and (d) PAEI.
3.2.2. X-ray diffraction (XRD) analysis
The XRD patterns of PAEI, PAEI/ZnO-KH570 (10 wt%), PAEI/
ZnO-KH550 (10 wt%) and ZnO are shown in Fig. 7. Pure PAEI with
no sharp diffraction peaks is completely amorphous in nature
(Fig. 7d). Fig. 7b and c shows the XRD patterns of BNCs with
10 wt% of ZnO-KH570 and ZnO-KH550, which indicate that the
morphology of ZnO nanoparticles was not changed during the
process. In Fig. 7a, a series of characteristic peaks: (1 0 0), (0 0 2),
(1 0 1), (1 0 2), (1 1 0), (1 0 3), (2 0 0), (1 1 2), (2 0 1), (0 0 4) and
(2 0 2) are noticed, which are in accordance with the zincite
phase of ZnO (International Center for diffraction data, JCPDS No.
36-1451).
Fig. 5. FT-IR spectra of: (a) PAEI, (b) PAEI/ZnO-KH570 (6 wt%), (c) PAEI/ZnO KH570
(8 wt%), (d) PAEI/ZnO-KH570 (12 wt%) and (e) ZnO-KH570.
ZnO-KH550 contents [Figs. 5 and 6(b–d)] exhibit the characteristic
absorption peaks corresponding to polymeric functional groups
and ZnO nanoparticles. In BNCs spectra the appearance of a broad
peak at around 400–600 cmꢁ1 which is related to Zn–O–Zn bonds,
confirmed the interaction of ZnO with synthesized PAEI and also by
increasing the amount of nanoparticles, the intensity of this peak
was increased.
3.2.3. Thermal properties (TGA and DSC analysis)
The thermal properties of BNCs were investigated by TGA. The
thermal gravimetric profiles of the BNCs (10 wt%) are shown in
Fig. 8. The thermal stability of both BNCs was increased compared
to pure polymer. This improvement in thermal stability may be
caused by the fact that the ZnO nanoparticles have larger surface
area which improves the thermal cover or preventing out-diffusion
of the volatile decomposition products.
Furthermore, the thermal properties of both BNCs (10 wt%)
were examined by DSC. The glass transition temperature (Tg) of the
bionanocomposites was decreased with respect to pure PAEI. The
Tg for PEA/ZnO-KH570 (10 wt%) and PEA/ZnO-KH550 (10 wt%) is
Fig. 6. FT-IR spectra of: (a) PAEI, (b) PAEI/ZnO-KH550 (6 wt%), (c) PAEI/ZnO-KH550
Fig. 8. TGA thermograms of PAEI, PEA/ZnO-KH550 (10 wt%) and PEA/ZnO-KH570
(10 wt%) under a nitrogen atmosphere at heating rate of 10 8C/min.
(8 wt%), (d) PAEI/ZnO-KH550 (12 wt%) and (e) ZnO-KH550.

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A. Abdolmaleki et al. / Materials Research Bulletin 47 (2012) 1123–1129
Fig. 10. UV/vis spectra of: (a) PAEI, (b) PAEI/ZnO-KH550 (6 wt%), (c) PAEI/ZnO-
Fig. 9. UV/vis spectra of: (a) PAEI, (b) PAEI/ZnO-KH570 (6 wt%), (c) PAEI/ZnO-KH570
KH550 (8 wt%), (d) PAEI/ZnO-KH550 (12 wt%) and (e) ZnO-KH550.
(8 wt%), (d) PAEI/ZnO-KH570 (12 wt%) and (e) ZnO-KH570.
160 and 167 8C, respectively. The DSC results showed the effect of
nanoparticles on the reaction between polymer chains and
modified ZnO nanoparticles. These results indicate that the
polymer chain mobility is enhanced in the presence of the filler
because of increasing the hydrogen bonding between polymer and
functionalized ZnO, while the hydrogen bonding between PAEI and
PAEI is decreased, so the Tg of BNCs is reduced.
expected that these materials can be used as a UV shielding
materials.
3.2.5. Morphology studies
FE-SEM images of bionanocomposites were taken to study the
morphological features and the representative images of 10 wt%
PAEI/ZnO-KH570 and 10 wt% PAEI/ZnO-KH550 bionanocompo-
sites were displayed in Fig. 11. These images show that ZnO
nanoparticles were dispersed homogeneously in nano scale in
polymer matrix.
According to these micrographs, KH570 modified ZnO nano-
particles (Fig. 11a and b), disperse better than the one which was
modified with KH550 (Fig. 11d and e) and also the size of particles
are smaller. For KH550 coupling agent, the functional group which
provides different interactions to ZnO nanoparticle is the amino
group. Various interactions between aminosilane and ZnO surface
were proposed as follows: (a) hydrogen bonding; (b) ionic
bonding; (c) covalent bonding with surface hydroxyl groups
[31–33]. Due to these interactions, the aggregation of nanopar-
ticles is more when ZnO is modified with KH550, so the distance
3.2.4. UV/vis absorption
The UV/vis absorption of ZnO-KH570, PAEI/ZnO-KH570 BNCs
and PAEI are shown in Fig. 9 and the UV/vis absorption of ZnO-
KH550, PAEI/ZnO-KH550 BNCs and PAEI are shown in Fig. 10. Pure
PAEI displays absorbance in the UV region due to its delocalized
p
-electrons and shows the maximum absorption peak at 459 nm
(Figs. 9a and 10a). The ZnO-KH570 and ZnO-KH550 show
maximum UV absorption peak at 338 and 368 nm, respectively
(Figs. 9e and 10e). In two different BNCs groups, by increasing of
ZnO contents, the maximum absorption peak of polymer is shifted
to the maximum absorption peak of modified ZnO nanoparticle.
The obtained BNCs have absorption around the UV region, so it is
Fig. 11. FE-SEM micrographs of (a and b) PAEI/ZnO-KH570 (10 wt%) and (c and d) PAEI/ZnO-KH550 (10 wt%).

A. Abdolmaleki et al. / Materials Research Bulletin 47 (2012) 1123–1129
1129
Fig. 12. TEM micrographs of (a) PAEI/ZnO-KH570 (10 wt%) and (b) PAEI/ZnO-KH550 (10 wt%).
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4. Conclusion
A novel optically active, biodegradable and nanostructured
PAEI was successfully synthesized through direct polyconden-
sation of amino acid based diol and diacid. The synthesized
polymer was thermally stable and shows nanostructure. PAEI/
ZnO BNCs were fabricated via embedding ZnO nanoparticles into
PAEI matrix by ultrasound irradiation process. The surface of
ZnO was modified with two different silane coupling agents
(KH570 and KH550), to achieve a uniform dispersity of ZnO
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particles with the suitable modifying agents, increase the
compatibility of ZnO particles with PAEI matrix, and also
efficiently improved the thermal stability of the PAEI/ZnO
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We gratefully acknowledge the partial financial support from
the Research Affairs Division Isfahan University of Technology
(IUT), Isfahan. Further partial financial support of Iran Nanotech-
nology Initiative Council (INIC), National Elite Foundation (NEF)
and Center of Excellence in Sensors and Green Chemistry (IUT) is
also gratefully acknowledged.
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