World Journal of Nano Science and Engineering, 2012, 2, 19-24
http://dx.doi.org/10.4236/wjnse.2012.21004 Published Online March 2012 (http://www.SciRP.org/journal/wjnse) 19
Synthesis and Characterization of Polymeric Composites
Embeded with Silver Nanoparticles
Hemant K. Chitte1, Narendra V. Bhat2*, Narayan S. Karmakar3,
Dushyant C. Kothari3, Ganesh N. Shinde4
1Dnyanasadhana College, Thane, India
2Bombay Textile Research Association, Mumbai, India
3Centre for Nanosciences and Nanotechnology, University of Mumbai, Mumbai, India
4Indira Gandhi College, New Nanded, India
Received November 30, 2011; revised December 12, 2011; accepted January 2, 2012
ABSTRACT
Silver nanoparticles were synthesized by chemical reduction method. The Ag nanoparticles (AgNP) were characterized
using UV-Vis spectroscopy which shows an absorption band at 420 nm confirming the formation of nanoparticles. For
any practical application of the silver nanoparticles it is necessary to stabilize it which can be done by making a com-
posite. In the present studies three polymers were chosen such that AgNP could be put to some practical use. Polyvinyl
Alcohol (PVA), Polypyrrole (Ppy) and Carboxymethyl cellulose (CMC) are important for use in textiles, electronics
and food/drug technologies respectively. Polymeric composites of PVA, PPy, and CMC were prepared by mixing the
aqueous solutions of the respective polymers and the colloidal suspension of pre-formed silver nanoparticles. Various
compositions containing 1% to 5% of Ag nanoparticles were prepared. Thin films of these composites were character-
ized by UV-Vis spectroscopy, X-ray diffraction and Scanning electron microscopy. X-ray diffraction showed the pres-
ence of the peaks at 2θ values of 38.1˚, 44.2˚, 64.4˚ and 78.2˚ corresponding to cubic phase of silver metal. SEM photo-
graphs revealed the presence of Ag nanoparticles of sizes varying from 40 to 80 nm. The electrical conductivity of these
materials was studied using the four probe method. The conductivity was found to increase from 10–6 for control sam-
ples to 10–3 S/cm after the formation of the nanocomposites.
Keywords: Silver Nanoparticles; Composites; Polypyrrole; PVA; CMC; Microscopy
1. Introduction
Nanotechnology has assumed a great importance in recent
years on account of its possible applications in several
areas such as electronics, pharmacy, computers, catalysis,
biotechnology etc. [1]. Metallic nano particles of Ag, Au,
Cu and Zn have been the focus of specific interest due to
its unique properties such as antibacterial, optical bi-sta-
bility, photoresponsivity etc. In spite of such importance
the instability of nanoparticles gives rise to aggregation
which deters its use for specific app lications.
Various methods for stabilizing and capping of nanopar-
ticles have been reported [2]. Coating of nanoparticle and
its surface modification with functional polymers have
been achieved to give resistance to oxidation and possi-
bility of embedding such modified nanoparticles in dif-
ferent composites. The interest in nano-coating is on ac-
count of combination of the properties of two or more
materials involved with the emphasis on the fact that one
of the materials (shell) will determine the surface proper-
ties of the particle while the other i.e. the core is com-
pletely encapsulated by the shell. Although the core will
not contribute to surface property it will be responsible
for optical, electrical and other properties of the compo s-
ites. It is also important to take into account the possible
interaction between the core and shell, so that th e unique
combination can be understood. Another main benefit of
coating nanoparticle is avoidance of spread of nanoparti-
cle to the environment due to bonding between the sub-
strate and coated nanoparticle. Thus the nanoparticle may
be safer to move to different places and use for specific
purposes.
For any practical application of the silver nanoparticles
it is necessary to stabilize the NPs which can be done by
making a composite. In the present studies three poly-
mers were chosen such that AgNP could be put to some
practical use. PVA, Ppy and CMC are important for use
in textiles, electronics and food/drug technologies re-
spectively. In the present paper we have synthesized the
composites of silver nanoparticles with Po lyvinyl alcohol,
Polypyrrole and Carboxymethyl cellulose. The procedure
*Corresponding a uthor.
C
opyright © 2012 SciRes. WJNSE

H. K. CHITTE ET AL.
20
adopted was to coat the pre-formed Ag nanoparticles
with the polymers in suspension. The nanocomposites
thus formed were characterized using UV-Vis spectros-
copy (UV-Vis), X-ray diffraction (XRD) and Scanning
electron Microscopy (SEM). The advantages of these
nanocomposites over the control polymer and industrial
applications will be reported in a separate communica-
tion.
2. Experimental
2.1. Preparation of Silver Nanoparticles
AgNO3 was dissolved in double distilled water to give a
solution of 0.001 M solution. Trisodium citrate (0.02 M)
was used as reducing agent. To 100 ml of silver nitrate
solution was added to trisodium citrate solution drop by
drop, over a period of 30 min and maintained at 80˚C.
The stirring was continued for 1 hr. It was found that
solution turns yellow. The yellow colour confirms the
formation of silver nanoparticles [3]. A large quantity of
such solution was made and served as the stock solution
for other e xp erim en t s.
2.2. Coating of Ag Nanoparticles by Polymers
The coating of silver nanoparticle by polypyrrole was
performed by addition of 4 ml of pyrrole to 600 ml of
silver nanoparticle solution. The solution was stirred con-
tinuously during and after addition and it was observed
that the conversion of pyrrole to polypyrrole takes place
within 15 min. However the stirring was continued for
another 1 hr so that the pyrrole fully polymerizes and
coats the Ag nanoparticle evenly. The color of the solu-
tion changes from yellow to steel grey to black. The ob-
tained solution was left in the ambient condition for an-
other 24 hr before the precipitated material was filtered
out and washed.
Polymeric composites of Polyvinyl alcohol and Car-
boxymethyl cellulose were prepared by mixing the aque-
ous solutions of the respective polymers and the colloidal
suspension of pre-formed silver nanoparticles. The solu-
tions of PVA and CMC were made in water using 4% of
powders (w/w) and stirring for one hour at 80˚C. To
these solutions were added the solution of AgNP to get
various compositions containing 1% to 5% of Ag. Thin
films of these solutions were casted on glass plates for
further analysis.
The results described in this paper are for composi-
tions all containing 1% w/w of Ag nanoparticles.
2.3. Methods of Characterization
All the preparations i.e. pure silver nanoparticles and the
composites were characterized by UV-Vis, XRD, SEM
and TEM. For this purpose UV-Vis Spectrometer of Var-
ian make Cary 5000 which could scan from 175 nm to
3300 nm was used. Diluted solution of nanop articles was
filled into the quartz cuv ette to obtain the spectrum. PAN
analytical Xpert pro X-ray diffractometer with Cu tube
was used for recording the XRD pattern. The specimen
in the form of thin coating on glass plate or PET film was
prepa red an d used for s canni ng in th e range of 10˚ to 80˚.
Scanning electron micrographs were obtained using JEOL
SEM model JSM 5400. The samples were mounted on the
stub and coated with a thin film of gold before observa-
tions. Transmission electron micrographs were obtained
by using Philips TEM CM200 operating at voltage of
200 kV. Structures of different polymers used for coating
of silver nanoparticles are shown in Figure 1.
3. Results and Discussions
3.1. Composite of Silver Nanoparticles with
Polypyrrole
3.1.1. U V-Vis Spectroscopy
The dispersions of silver nanoparticles display intense
colors due to the plasmon resonance absorption. The
surface of a metal is like plasma, having free electrons in
the conduction band and positively charged nuclei. Sur-
face plasmon resonance is a collective excitation of the
electrons in the conduction band near the surface of the
nanoparticles. Electrons are limited to specific vibrations
modes by the particle’s size and shape. Therefor e, metal-
lic nanoparticles have characteristic optical absorption
spectra in the UV-Vis region [3].
The UV-Vis absorption spectrum of pure silver nanopar-
ticle is shown in Figure 2. One can clearly see strong ab-
sorption at 417 nm, confirming the formation of silver
nanoparticles. The peak at 417 nm is attributed to the
surface plasmon reso nance.
UV-Vis Spectra for the solution in which pyrrole is
added is shown in Figure 3. Curve A of Figure 3 is UV-
Vis spectrum of silver nanoparticle solu tion. It shows the
strong absorption peak at 417 nm. Curve B of Figure 3
corresponds to Ag nanoparticle solution in which pyrro le
Figure 1. Molecular structures of Carboxy methyl cellulose,
Polypyrr o le and Polyvi nyl alcohol.

H. K. CHITTE ET AL. 21
Figure 2. UV-Vis absorption spectra of colloid solution of
Ag nanoparticles.
Figure 3. A: UV-Vis absorption spectra of colloid solution
of Ag nanoparticles; B: Ag/PPy nanoparticle.
was added and allowed to polymerize for sufficient dura-
tion. It can be noted that the peak at 417 nm observed
earlier for pure Ag nanoparticles has now disappeared.
The color of the solution changes from yellow to steel
grey to black. This is due to fact that the PPy coats
around Ag nanoparticles and as the color of polypyrrole
is black, the entire solution and the precipitated compos-
ite gets black color. In addition the strong scattering from
the PPy shell possibly screened the surface and as a re-
sult the plasmon r eson ance does not occur.
3.1.2. X-Ray Diffrac ti on Anal ysis
X-ray diffraction pattern for pure silver nanoparticle re-
ported in literature shows four distinct diffraction peaks
at 38.7˚, 44.1˚, 64.6˚ and 78.3˚ [JCPDS No 03-0931].
These correspond to cubic, crystalline structure of silver
and are assigned to (111), (200), (220) and (311) planes
of silver respectively. Figure 4 shows X-ray diffraction
pattern of PPy coated Ag nanoparticle. This shows all the
four characteristic peaks due to silver crystalline struc-
ture and in addition a broad peak in the region 20˚ to 24˚
due to the amorphous structure of polypyrrole [4].
The four peaks observed for Ag/PPy are at 2θ angles
of 37.8˚, 44.0˚, 64.2˚ and 77.1˚. These values are slightly
lower than those reported in JCPDS. The particle size of
the silver nanoparticle was calculated from the line broaden-
ing using the Scherrer’s formula D = kλ/βcosθ. The sizes
were calculated from all the four peaks and were found
to be 27 nm, 23 nm, 23 nm and 20 nm respectively. The
XRD pattern did not change even after 60 days after pre-
paration. This indicated that the PPy coating prevented
the Ag nanoparticles from being oxidized even in air,
compared with the uncoated Ag nanoparticles, which is
evidence of the protection that the PPy exerts against
oxidation of the Ag core. Thus, quite stable Ag nanopar-
ticles could be fabricated with PPy coating.
3.1.3. Transmission Electron Microscopy
Figure 5(a) shows TEM image of pure silver nanoparti-
cle and one can see minimum size of Ag nanoparticle as
about 20 nm. Large particles of different sizes in the
range from 20 nm to 50 nm were also seen, which are
probably due to aggregation or clustering of the nanopar-
ticle. Figure 5(b) shows the TEM image of polypyrrole
coated silver nanoparticle. One can note beautiful core/
shell structure. The Ag nanoparticles seem to be embed-
ded in the PPy matrix. This feature is very much different
from pure polypyrrole, whose morphology is mainly
spherulitic or globular with the average size of 0.8 mi-
crons, as seen in Fi gure 5(c).
Figure 4. XRD Patterns of Ag/Ppy nanoparticles.

H. K. CHITTE ET AL.
22
(a)
(b)
(c)
Figure 5. Micrographs (a) Pure Ag nanoparticles, (b) Ag
nanoparticles coated with PPy and (c) SEM of pure Ppy.
3.2. Composites of Silver Nanoparticles with
PVA
3.2.1. U V-Vis Spectroscop y o f Ag NP/ PVA
The nanocomposite films of various compositions were
checked for their absorption patterns. The composite films
exhibit a broad surface Plasmon absorption band peaking
at approximately 420 nm (Figure 6). This result is in
agreement with the optical absorption spectra of Ag
nanoparticles embedded in different polymer matrices
like polyacrylonitrile, nylon etc. The shift to the longer
wavelength and broadening of the band upon incorpora-
tion of Ag nanoparticles into PVA can be induced by
agglomeration of the Ag nanoparticles or change of the
dielectric properties of th e surrounding environment.
3.2.2. X-Ra y Diffr ac ti on
X-ray diffraction pattern of the nanocomposite films
showed many peaks at different 2θ values as shown in
Figure 7. The peaks around 20˚ have resulted from the
crystalline parts of PVA molecules. (In fact it is a group
of three peaks corresponding 19˚, 21˚, 23˚, not seen re-
solved here due to reduced size of the figure). This agrees
well with the previous reported work for the PVA [5]. In
addition very intense peaks were observed at 38˚, 44˚, 64˚
and 78˚ which are due to cubic form of silver and also
agrees well with the literature [JCPDS No 030931]. Thus
we can see that a homogeneous nanocomposite film of
PVA with Ag N P ha s b een formed.
The nanocomposite of PVA/Ag was observed using
AFM. Figures 8(a) and (b) show the surface morphology
of the films in 2 and 3 dimensions. One can see easily the
silver nanoparticles of size 40 nm protruding out of the
surface. This structure is certainly much different from
that for pure PVA, which shows mainly a planar surface
as seen in Figure 8(c).
3.3. Composites of Silver Nanoparticles with
CMC
The nanocomposites of CMC + Ag were also investigat ed
Figure 6. UV/Vis spectra of PVA/Ag nanocomposites of
different concentrations (a) Control PVA; (b) 0.2% Ag con-
tent; (c) 0.5% Ag content (d) 1.0% Ag content.
Figure 7. X-ray diffractogram of PVA/ Ag nanocomposites.

H. K. CHITTE ET AL. 23
(a)
(b)
(c)
Figure 8. Morphological f of composite of AgNP+
PVA seen using AFM: (a) Planar surface; (b) 3-D view of
surface and (c) of pure PVA film.
eatures
2
θ
Intensity
Figure 9. X-ray diffraction pattern of CMC + Ag nanopar-
ticles.
(a)
(b)
Figure 10. SEM micrographs of (a) Pure CMC and (b)
CMC + Ag nanoparticles co nsions.
e X-ray diffract-
clu
using the UV/Vis spectroscopy and one could easily ob-
serve the abso rption band at 420 nm. Th
tion also revealed that a good composite has been formed
as seen by the presence of peaks due to silver (Figure 9).
Morphological studies using SEM provided interesting

H. K. CHITTE ET AL.
24
tic
and Carboxy-
m
permission. Thanks are al
r. V. E. Walunj for the help
[1] A. Franks, “Review Article: Nanotechnology,” Journal of
information about the granular structure of pure CMC
changing to square type of formations with silver nanopar-
les embedded in the center (Figure 10).
Polymeric Nanocomposites containing Ag NP could
be prepared with three industrially important polymers ,
namely, Polyvinyl alcohol, polypyrrole
ethyl cellulose. The Ag NP gets coated with the poly-
mers which improves its stability and functionality. Sig-
nificant changes were noted in the surface morphology
and homogeneous distribution of Ag NP was observed.
4. Acknowledgements
The authors wish to express thanks to Director, BTRA
so for his interest and necessary
due to Mr. A. V. Gore and M
during experimental work.
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