Surface functionalized Tio 2 nanoparticle designed for the preparation of chiral poly(amide-imide) bionanocomposites containing phenylalanine linkage

Article abstract of DOI:10.1080/15533174.2013.769005

The surface of titanium dioxide (TiO2) nanoparticles was treated with a silane coupling agent of γ-aminopropyl-triethoxy silane. An optically active poly(amide-imide) (PAI) was synthesized by the indirect polycondensation reaction of the L-phenylalanine b

Full text of DOI:10.1080/15533174.2013.769005

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Synthesis and Reactivity in Inorganic, Metal-Organic,
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Surface Functionalized TiO Nanoparticle Designed
2
for the Preparation of Chiral Poly(amide-imide)
Bionanocomposites Containing Phenylalanine Linkage
a b
a
Shadpour Mallakpour
& Samira Moslemi
a
Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan
University of Technology, Isfahan, 84156-83111, Islamic Republic of Iran
b
Nanotechnology and Advanced Materials Institute, Isfahan University of Technology,
Isfahan, 84156-83111, Islamic Republic of Iran
Accepted author version posted online: 04 Apr 2013.
To cite this article: Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry (2013): Surface
Functionalized TiO Nanoparticle Designed for the Preparation of Chiral Poly(amide-imide) Bionanocomposites
2
Containing Phenylalanine Linkage, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, DOI:
10.1080/15533174.2013.769005
To link to this article: http://dx.doi.org/10.1080/15533174.2013.769005
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Surface Functionalized TiO
2
Nanoparticle Designed for the Preparation of Chiral
Poly(amide-imide) Bionanocomposites Containing Phenylalanine Linkage
∗
, 1, 2
1
Shadpour Mallakpour
and Samira Moslemi
1
Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan
University of Technology, Isfahan 84156-83111, Islamic Republic of Iran.
2
Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan
8
4156-83111, Islamic Republic of Iran.
Abstract
2
The surface of titanium dioxide (TiO ) nanoparticles was treated with a silane coupling
agent of γ-aminopropyl-triethoxy silane. An optically active poly(amide-imide) (PAI) was
synthesized by the indirect polycondensation reaction of the L-phenylalanine based diacid
chloride and 4,4′-diaminodiphenylether in the presence of triethylamine in N-methyl-2-
2
pyrrolidone. Then PAI and surface modified TiO nanoparticles were used to produce a
polymer based bionanocomposites (BNC)s via ultrasonic irradiation process. The obtained
BNCs were characterized by means of X-ray diffraction, electron microscopy and
thermogravimetric analysis techniques. The results showed that the nanoparticles are
homogeneously dispersed in PAI matrix with particle size ranging 30-50 nm.
∗
Corresponding author. Tel.; +98-311-391-3267; FAX: +98-311-391-2350.
E-mail address: mallak@cc.iut.ac.ir, mallak777@yahoo.com, mallakpour84@alumni.ufl.edu.
1
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Keywords TiO nanoparticles; ultrasonic irradiation; electron microscopy; thermal stability;
2
bionanocomposite
INTRODUCTION
Combination of optically activity character and beneficial of thermally stable polymer
properties caused to generate a new class of materials with functional potential for separation
[1]
sciences. Recently, synthesis of polymers by incorporation of optically active parts such as
[
2]
amino acids in backbone structure showed an important field in macromolecular science.
These polymers such as polyimides, polyamides and poly(amide-imides) (PAI) find a wide range
[3]
of potential applications based on their chiral structures.
Aromatic polyimides are well-known polymers that have attractive characteristics such as
high thermal stability and excellent physical properties as well as outstanding chemical
[
4-7]
resistance.
They have high-performance properties but the major disadvantage of these
compounds is insolubility and unprocessability after conversion from the poly(amic-acid) to
[8]
form the polyimide. PAI contains both amide and heterocyclic imides structures along the
polymer backbone and possesses high thermal stability, good chemical resistance, excellent
mechanical properties and processability. These properties in addition to different possible
[9,10]
physical and chemical interactions, being promising matrix candidate for hybrid materials.
In recent years, organic and inorganic nanoparticles (NP)s have attracted great attention.
Among the different kinds of, titanium dioxide (TiO ) is one of the most potential materials,
nontoxicity and chemical inertness that cause wide applications in the fields of electronic and
2
[11,12]
photonic.
TiO
2
has three crystalline polymorphs: rutile, anatase and brookite .The most
2
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common form of bare TiO
2
crystal that used in many industries such as paints and cosmetics is
rutile that stable at high temperatures. The anatase to rutile transition is an irreversible procedure
o
[13-15]
and usually generated within a temperature range of 500-1000 C.
TiO
2
nanocomposites
have many applications especially in medicine, cleaning machining, jointing and chemistry
[16-20]
industry.
Other application fields of them are ultraviolet light, absorbent coating,
[21-24]
interference filter, antireflective coating, and optical waveguides.
In this study we wish to report the synthesis and characterization of optically active PAI
by polycondensation reaction of N,N′-(pyromellitoyl)-bis-phenylalanine diacid chloride 5 and
4
,4′-diaminodiphenylether 6, in the present of triethylamine (Et
NPs were treated with coupling agent of γ-aminopropyl-triethoxysilane (KH550) to introduce
organic functional groups on to the surface of TiO . Then optically active PAI/TiO
3
N) at low temperature. The TiO
2
2
2
bionanocomposites (BNC)s were synthesized under ultrasonic irradiation conditions. The
resulting novel BNCs are characterized by Fourier transform infrared spectroscopy (FTIR), UV-
visible spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and their
surface morphology were investigated by scanning electron microscopy (SEM), field emission
scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis.
EXPERIMENTAL
Materials
All chemicals were purchased from Fluka Chemical Co. (Buchs, Switzerland), Aldrich
Chemical Co. (Milwaukee, WI), Riedel-deHaen AG (Seelze, Germany) and Merck Chemical Co.
Pyromellitic dianhydride (benzen-1,2,4,5-tetracarboxylic dianhydride) (from Merck Chemical
CO., Germany) and 4,4′-diaminodiphenylether were used as obtained without further
3
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purification. N-Methyl-2-pyrrolidone (NMP) was dried over BaO, by fractional distillation. L-
Phenylalanine was used as obtained without further purification. Nanosized TiO powder was
2
purchased from nanosabz Co. with average particle sizes of 30-50 nm. Coupling agent KH550
obtained from Merck Chemical Co.
Synthesis of Optically Active Diacid Monomer
N,N΄-(Pyromellitoyl)-bis-L-phenylalanine diacid chloride 5 was prepared according to a
[25,26]
typical reported procedure (Scheme 1).
Synthesis of Polymer
[27]
The chiral PAI was prepared was synthesizes according to our previous study.
Preparation of PAI/TiO BNCs
.3 g of TiO NPs was suspended into 10 mL acetone and was added to 10 weight
percentage of silane coupling agent (KH550), which was dissolved in 10 mL H O. Then the
mixture of TiO /KH550 was sonicated for 30 min at room temperature. Subsequently the solvent
was removed and dried. Finally different amounts of modified TiO NPs (5, 10, 15 and 20 wt.%)
2
0
2
2
2
2
were added to the novel PAI and the mixture was dispersed in 20 mL of absolute ethanol and
o
sonicated for 4 h. The solvent was removed and the precipitate was dried in vacuum at 80 C for
2
h.
Specimens Characterization Techniques
1
Proton nuclear magnetic resonance ( H NMR, 400 MHz) spectrum was recorded by
Bruker (Germany) advance 400 instrument, at room temperature (RT) in DMSO-d solution.
6
Multiplicities of proton resonance were chosen as singlet (s) and multiplet (m). Specific rotations
4
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were determined by a Jasco Polarimeter (Japan). Inherent viscosities were measured by a
standard procedure using a Cannon-Fenske routine viscometer (Germany) at the concentration of
0
.5 g/dL at 25ºC. The FTIR adsorption spectra were recorded on a Jasco-680, Japan IR
spectrophotometer with KBr pallets. The band intensities are categorized as weak (w), medium
m), shoulder (sh), strong (s) and broad (br). UV-Vis absorption of PAI/TiO BNCs was
(
2
measured by UV-Vis spectrometer, JASCO V-750 in the spectral range between 200 and 800
nm. Thermogravimetric analysis (TGA) data is performed with STA503 winTA instrument in
nitrogen atmosphere at a heating rate of 10ºC/min from 25ºC to 800ºC. The XRD patterns of the
polymer and BNCs were recorded by Philips X'PERT MPD, that were measured for 2θ, using Cu
Kα incident beam (λ = 1.51418Å) in the range of 10-80o at the speed of 0.05o/min. FESEM,
(
Hitachi, S-4160), SEM, (XL30, Philips) and TEM, (Philips, CM 120) images were investigated
the morphology of dispersion of NPs on PAI matrix. Formation of PAI/TiO BNCs was occurred
2
on a MISONIX ultrasonic liquid processor, XL-2000 Series by wave of frequency 2.25 × 104 Hz
and power 100 W.
RESULTS AND DISCUSSION
Surface Modification of TiO
The major aim for surface modification of TiO
NPs in polymer matrix. The surface of TiO NPs was modified by KH550 coupling agent. The
reaction mechanism indicate that the hydroxyl groups on the surface of TiO NPs were reacted
and this cause to formation of Ti-O-Si bonds on
2
NPs
2
NPs is to prevent the agglomeration of
2
2
[27,28]
with ethoxyl groups of the KH550 reagent
the surface of TiO NPs.
2
5
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For the investigation of organic part in the structure of TiO NP, FTIR spectroscopy is a
2
-1
powerful technique. Broad bands at 3500 and 3422 cm were attributed to interactions between
hydroxyl groups on TiO and a broad peak at 500-800 cm-1 is belonged to the Ti-O-Ti stretching
band. There is a peak around 2870-2928 cm-1 for TiO modified by KH550 that is attributed to
CH stretching band of KH550. Obtained results confirmed the formation of surface modified
TiO (Figure 1a and 1b).
2
2
2
Synthesis and Characterization of Monomer and Polymer
The FTIR spectrum of compound 4 (Scheme 1) showed a broad and strong peak at 2354-
−
1
−1
3
463 cm , which was assigned to the COOH groups. Also peaks around 1766, 1720 cm ,
[28]
-
belong to carbonyl stretching of imide rings and C-N bonds. Absorptions at 1382 and 727 cm
1
were related to the presence of the imide ring. Compound 5 was prepared from the reaction of
[26]
molecule 4 with thionyl chloride.
Polycondensation reaction of compound 5 with aromatic diamine 6 in NMP at room
temperature provided an optically active PAI 7 (Scheme 2). Due to the presence of amino acid
linkages in the structure of polymer, this PAI is optical activity. The specific rotation of this
polymer is =-178.8 (0.05 g in 10 mL of DMF)
The FTIR spectrum of PAI showed a broad and strong peak at 3379 cm−1, which was
assigned to the N-H group and two absorption bands at 1776 and 1725 cm−1 due to the
symmetrical and asymmetrical imides carbonyl stretching vibrations (Figure 1c). Absorptions at
1
382 and 727 cm-1 were related to the presence of the imide ring.
Preparation of PAI/TiO BNCs
2
6
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The procedure for the preparation of PAI/TiO BNCs is demonstrated in Scheme 3. PAI
2
was dispersed in absolute ethanol. A uniform colloidal dispersion was obtained after sonicated at
room temperature. The suspension was mixed with the appropriate amount of TiO
2
/KH550
powder to produce 5, 10, 15 and 20 wt.% based on the PAI content.
FTIR Spectra PAI/TiO
2
BNCs
Figure (2a-2d) exhibited the FTIR spectrum of PAI/TiO
2
BNCs (5, 10, 15 and 20 wt.%).
-1
All of these figures show a broad and strong peak at 3379 cm , which was assigned to the N-H
-1
group and two absorption bands at 1775 and 1723 cm due to the symmetrical and asymmetrical
imides carbonyl stretching vibrations. The spectra of BNCs show a broad absorption peak at
-
1
5
2
00-800 cm that is belonged to the Ti-O-Ti stretching band. There are two peaks at 2928 and
-1
870 cm that is attributed to CH stretching band of KH550. In these BNCs the peaks intensity
contents.
related to Ti-O-Ti bond were enhanced with increasing in TiO
XRD patterns of PAI/TiO BNCs
The structure and crystalline phase of BNCs were studied by XRD analysis. Figure 3 (a-
c) shows the XRD patterns of the PAI, TiO and PAI/TiO BNC 10 wt.%, respectively. The
2
2
2
2
XRD of BNC 10 wt.% revealed three main peaks at 2θ values 25°, 36° and 48°, corresponding to
the characteristic absorption peaks of the anatase titania phase (101, 004 and 200) and 2θ values
2
7°, absorption peak of the rutile titania phase (110). These results indicated that titania particles
[28]
did not change after reacting with the KH550 coupling agent. The XRD pattern in Figure 3a
shows that the pure PAI has amorphous nature.
Figure 3b shows the existence of anatase and rutile phase for bare TiO
2
NPs. Also Figure
3
c shows the presence of anatase and rutile crystalline phase of TiO NPs are distinguishable in
2
7
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BNC structure. According to Figure 3, there was no morphological change that has been detected
during the process of BNC preparations related to TiO
2
NPs.
The average crystallite size of TiO NPs in the BNCs were calculated by the Debye-
2
Scherrer equation,
). Where D is the crystallite size β is the full width at half
maximum, λ is wavelength of the radiation, K is the Scherrer constant and θ is the Bragg’s
[
29]
angle.
Morphology Analysis
Figure 4 shows SEM micrograph of pure PAI and PAI/TiO
magnifications, which indicates good homogeneous distribution of NPs in the polymer matrix.
Figure 5 shows the FESEM micrograph of pure PAI and PAI/TiO BNC that has a
homogeneous microstructure and dispersed as global beads. From this data it can be concluded
that the average crystallite size for PAI is 58 nm and for TiO NPs in polymer matrix is 65 nm.
Figure 6 shows the TEM micrographs of PAI/TiO (10 wt.%) BNC. The TiO NPs are well
2
BNC with different
2
2
2
2
dispersed in the polymer matrix and average particle size distribution are remain a diameter size
from 30 nm to 50 nm, representing that the KH550 coupling agent cooperate an important role in
dispersion of the NPs. In modified TiO the organic chains of KH550 can perform steric
2
hindrance between inorganic NPs and avoid their aggregation.
Thermogravimetric analysis
The thermal properties of the PAI and PAI/TiO2 BNCs were assessed by TGA at a
heating rate of 10oC/min, under a nitrogen atmosphere (Figure 7). Table 1 shows the values of
the thermal degradation of the pure PAI and TiO2/PAI BNCs, including the temperature at
8
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o
which 5% (T
index (LOI) .
5
) and 10% (T10) degradation occurs, char yield at 800 C and also limiting oxygen
[
30]
LOI = 17.5 + 0.4 char yield
From these data it is clear that the PAI had a high decomposition temperature of about
o
3
8
80 C, which was further improved when TiO
2
was introduced. The char yield of pure PAI at
o
o
00 C is 52%, and for those of the BNCs (PAI/TiO2 5, 10, 15, 20wt%) at 800 C are in the range
of 52-72%, they were enhanced with an increase of TiO NPs content in the PAI.
2
UV-vis Absorption
The UV-Vis absorption spectra of pure PAI and PAI/TiO
maximum absorption peaks of pure PAI and TiO appeared at 339 nm, however the maximum of
PAI/TiO BNCs is red shifted to 355 nm. The observed absorption is around the UV region
2
BNCs are shown in Figure 8. The
2
2
representative that this type of composite could be used as a paint-on or spray-on coating to
shield against UV light.
CONCLUSIONS
In the present study, a high performance, thermally stable optically active PAI was
successfully prepared by indirect polycondensation technique. The polymerization was carried
out by reaction of natural amino acid based L-phenylalanine diacid chloride and 4,4′-
diaminodiphenylether using NMP/Et
3
N as a solvent system. This synthetic polymer is supposed
due to the presence of amino acid in the polymer structure. KH550 was
modified to introduce organic functional groups on the surface of TiO which cause to improved
compatibility and led to better dispersion of TiO NPs in the polymer matrix. The morphology
study of synthesized nanocomposites by TEM exhibited the TiO NPs are well dispersed in the
[31-33]
to be biodegradable
2
2
2
9
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polymer matrix and average particle size distribution are remain a diameter size from 30 nm to
5
0 nm. FESEM show average crystallite size for PAI is 58 nm and for TiO NPs in the polymer
2
matrix is 65 nm, respectively.
Acknowledgments
We gratefully acknowledge the partial financial support from the Research Affairs Division
Isfahan University of Technology (IUT), Isfahan. The partial support of Iran Nanotechnology
Initiative Council (INIC), National Elite Foundation (NEF) and Center of Excellency in Sensors
and Green Chemistry (IUT) is gratefully acknowledged.
Reference
1
2
3
4
5
6
7
8
9
1
1
1
. Mallakpour S, Dinari M, J. Macromol. Sci. Part A: Pure Appl. Chem, 2011; 48, 644-652.
. Mallakpour S, Zadehnazari A, Express Polym. Lett, 2011; 5, 142-146.
. Mallakpour S, Rafiee Z, Iran. Polym. J, 2008; 17, 907-915.
. Ree M, Macromol. Res, 2006; 14, 1-10.
. Seckin T, Koytepe S, Ozdemir I, Cetinkaya B, J. Inorg. Organomet. Polym, 2003; 13, 9-15.
. Liu X, Xu W, Ye G, Gu Y, Polym. Eng. Sci., 2006; 46, 123-136.
. Kong Y, Du H, Yang J, Shi D, Wang Y, Zhang Y. Xin W, Desalination, 2002; 146, 49-54.
. Mallakpour S, Amino Acids, 2011; 40, 487-492.
. Yamazaki N, Matsumoto M, Higashi F, J. Polym. Sci. Polym. Chem. Ed., 1975; 13, 1373-
386.
0. Jonquieres A, Clement R, Lochon P, Eur. Polym. J, 2005; 41, 783-791.
1. Phang S.W, Kuramoto N, Polym. Composites, 2009; 30, 970-981.
10
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1
1
2. Peining Z, Nair A.S, Shengyuan Y, Ramakrishna S, Mater. Res. Bull, 2011; 46, 588-593.
3. Dzunuzovic E, Marinovic Cincovic M, Vukovic J, Jeremic K, Nedeljkovic J. M, Polym.
Composites, 2009; 30, 737-743.
4. Sawada H, Sawada E, Kakehi H, Kariya T, Mugisawa M, Chounan Y, Miura M, N. Isu,
Polym. Composites, 2009; 30, 1848-1852.
1
1
1
1
1
2
1
2
2
5. Nie X, Zhuo S, Maeng G, Sohlberg K, Int. J. Photoenergy, 2009; 2009, 1-8.
6. Ray S. S, Mater. Res. Bull, 2002; 37, 813-822.
7. Price G.J, Lenz E.J, Ansell C.W.G, Eur. Polym. J, 2002; 38, 1531-1540.
8. Mohammed Bahadur N, Furusawa T, Sato M, Kurayama F, Suzuki N, Mater. Res. Bull,
010; 45, 1383-1394.
9. Tolke T, Kriltz A, Rechtenbach A, Thin. Solid. Films, 2010; 518, 4242-4251.
0. Yang S, Tang W, Ishikawa Y, Feng Q, Mater. Res. Bull, 2011; 46, 531-540.
1. Munoz O, Volten H, Hovenier J.W, Min M, Shkuratov Y.G, Jalava J.P, van der Zande W.J,
Waters L.B.F.M, Astron. Astrophys, 2006; 446, 525-536.
2
2
2
2
2
2
2
2
2. Devore J.R, J. Opt. Soc. Am, 1951; 41, 416-422.
3. Li H, Jiang B, Schaller R, Wu J, Jiao J, J. Phys. Chem. C., 2010; 114, 11375-11384.
4. Que W, Zhou Y, Lam Y.L, Chan Y.C, Kam C.H, Thin. Solid. Films., 2000; 16, 358-364.
5. Mallakpour S, Tirgir F, Sabzalian M.R, J. Polym. Res., 2011; 18, 373-382.
6. Mallakpour S.E, Hajipour A.R, Habibi S, J. Appl. Polym. Sci., 2002; 86, 2211-2223.
7. Mallakpour S, Dinari M, J. Inorg. Organomet. Polym., 2012; 22, 929–937.
8. Chen J, Zhou Y.M, Nan Q.L, Ye X.Y, Sun Y.Q, Wang Z.Q, Zhang S.M, Appl. Surf. Sci.,
008; 255, 2244-2253.
11
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2
3
3
3
3
9. Nakayama N, Hayashi T, Polym. Degrad. Stabil., 2007; 92, 1255-1264.
0. Krevelen D.V, Hoftyzer P, Properties of polymers, Third ed., Elsevier, Amsterdam, 1976.
1. Mallakpour S, Dinari M, Polymer 2011; 52, 2514-2525.
2. Mallakpour S, Tirgir F, Sabzalian M.R, J. Polym. Environ 2010; 18, 685-695.
3. Mallakpour S, Asadi P, Sabzalian M.R, Amino Acids 2011; 41, 1-8.
Table 1 Thermal properties of the PAI and PAI/TiO BNC
2
12
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o
a
o
b
c
d
Polymer
PAI
T
5
( C)
T
10 ( C)
Char Yield(%)
LOI
352
382
391
396
52
57
60
38.3
40.3
41.5
PAI/TiO
PAI/TiO
PAI/TiO
wt%)
PAI/TiO
wt%)
Temperature at which 5 and 10% weight loss was recorded by TGA at heating rate of 20ºC min
in N atmosphere.
Weight percent of the material left undecomposed after TGA at maximum temperature 800 C
2
(5 wt%)
370
2
(10wt%)
377
2
(15
(20
3
3
83
90
404
410
63
67
42.7
44.3
2
a
1
b
-
2
o
in N atmosphere.
2
c
o
Limiting oxygen index (LOI) evaluated at char yield at 800 C.
13
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Caption for Schemes
Scheme 1. Synthesis of monomer 5.
Scheme 2. Polycondensation reactions of monomer 5 with aromatic diamine 6.
Scheme 3. Preparation of PAI/TiO BNCs.
2
Legend for Figures
NPs (a), TiO / KH550 (b) and PAI (c).
Figure 2. The FTIR spectra of PAI/TiO (5 wt.%) (a), PAI/TiO (10 wt.%) (b), PAI/TiO
wt.%) (c) and PAI/TiO (20 wt.%) (d).
Figure 3. The XRD patterns of PAI (a), bare TiO
Figure 4. The SEM micrograph of pure PAI and PAI/TiO
Figure 5. The FESEM micrograph of pure PAI and TiO /PAI (10 wt.%) BNCs.
Figure 6. The TEM micrograph of PAI/TiO (10 wt%) BNCs.
Figure 7. TGA thermograms of PAI and PAI/ZnO BNCs with different ZnO content.
Figure 8. The UV-Vis spectra of pure PAI (a), PAI/TiO (5 wt.%) (b), PAI/TiO (10 wt.%) (c),
PAI/TiO (15 wt.%) (d) and PAI/TiO (20 wt.%) (e).
Figure 1. The FTIR spectra of TiO
2
2
2
2
2
(15
2
2
(b) and PAI/TiO
2
(10 wt%) (c).
2
(10 wt.%) BNCs.
2
2
2
2
2
2
14
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Scheme 1
Scheme 2
Scheme 3
15
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Figure 1
Figure 2
16
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Figure 3
Figure 4
17
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Figure 5
Figure 6
18
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Figure 7
Figure 8
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