SYNTHESIS AND CHARACTERISTICS OF Ag- POLYMER
NANOCOMPOSITES
C. J. Huang, W. P. Hsieh, H. C. Yao, M. C. Chiu and F. S. Shieu1
1
Department of Materials Engineering, National Chung Hsing University, Taichung 402,
Taiwan
Abstract
In this study, a metal chelate polymer (MCP) chemical approach has been adopted to
fabricate metal-containing polymer used in metal-polymer nanocomposite. The
silver-containing polymer was prepared by adding silver nitrate (AgNO3) to a solution of
polyvinyl acetate (PVAc) dissolved in formic acid (HCOOH) to form the PVAc-AgNO3 MCP
solution, and the resultant was cast to form the MCP film. The mechanism for generating
silver nanoparticles in the MCP system without addition of the reducing agent, and the effect
of variant AgNO3 concentration on the variety in the structure of PVAc matrix have been
investigated. The characteristics of this MCP film were analyzed by Fourier transform
infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy
(XPS).
As evidenced by the XRD results, formic acid played the role of reducing agent in the
generation of silver nanoparticle in the MCP film. The O1s spectrum of the XPS revealed that
the PVAc polymer in the MCP film was hydrolyzed to obtain the PVAc/PVOH structure. To
confirm the amphiphilic property of the MCP, the 0.5 wt% AgNO3 MCP system were
dispersed in the formic acid aqueous medium to form the Ag-containing micelles, and the
relation morphologies between micelle and silver nanoparticle were also investigated by
transmission electron microscopy (TEM). The TEM analysis showed that these 0.5 wt%
AgNO3 MCP micelles carried a core-Ag shell morphology, and the micellar solution was
stable for more than one month as well as no sign of precipitation appeared.
KEYWORDS: metal chelate polymer, polyvinyl acetate, nanocomposite, silver nanoparticle,
Ag-containing micelles.
1. Introduction
The novel properties of nanocomposites provide new options for electric, magnetic, optical
and catalytic applications [1-4]. Recently a great deal of investigations has been focused on
the synthesis of metal-containing polymer for using in nanocomposites [5-9]. Our previous
study showed that Ag metal-polymer films fabricated from a metal chelate polymer (MCP) of
silver nitrate (AgNO3) and polyvinyl acetate (PVAc) by a chemical approach exhibited high
electric conductivity and electromagnetic interference (EMI) shielding effectiveness [10].
These MCP films of PVAc-AgNO3 were prepared by adding silver nitrate (AgNO3) to a
solution of polyvinyl acetate (PVAc) dissolved in formic acid (HCOOH) to form the
PVAc-AgNO3 MCP solution, and the resultant was cast into a MCP film. The film was then
reduced by reducing agent such as sodium borohydride (NaBH4) to obtain a metallized film of
reduced metal chelate polymer (RMCP). The effects of AgNO3 concentration and the
reduction condition in the MCP system that needed to prepare the metallized RMCP films had
been studied in the previous study. The electric conductivity of the PVAc polymer was found
improved by increasing the AgNO3 content, and with the same AgNO3 concentration, the
electric conductivity of the RMCP treated with reducing agent was found higher than that of
the MCP film. The X-ray diffraction results also indicated that crystalline Ag particles were
not only present in the RMCP film, but also found existed in the MCP film.
In this paper, for further to understand the factor of the generating of silver nanoparticles in
the MCP system without adding reducing agent, the role and function of the formic acid
solvent in the MCP system, and the effect of variant AgNO3 concentration on the variety in
the structure of PVAc matrix have been further investigated and reported. In this study, MCP
films of 0.5 wt% and 2.0 wt% AgNO3 were prepared, and the characterizations of these MCP
films were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction
(XRD) and the X-ray photoelectron spectroscopy (XPS).
In the XRD analysis, the diffraction peak of metallic silver was identified after introducing
formic acid into the PVAc-AgNO3 MCP system. This indicates the formic acid not only
played the role of a solvent for the MCP, but also acted as a reducing agent to the AgNO3.
Both the FTIR and the XRS results also showed that the molecular structure of the PVAc
matrix in the MCP system had undergone hydrolysis to form the PVAc/PVOH structure with
plentiful amount of hydroxyl groups. Owing to the PVAc/PVOH structure, these partially
hydrolyzed MCP chains became amphiphilic, and with a higher water affinity than the native
PVAc, they were capable of self-assembly in the aqueous media to form micelles.
To confirm the amphiphilic property of the MCP, a mixed solvent of HCOOH/H2O (volume
ratio=1:1.2) was thus introduced to the 0.5 wt% AgNO3 MCP system to prepare the micellar
solution. The morphologies of the MCP micelles, and the incorporation of metal nanoparticles
into the micelles were investigated by transmission electron microscopy (TEM). As revealed
by the TEM images, the dried specimen of 0.5 wt% AgNO3 MCP micellar solution was
observed to have micelles bearing the core-shell structure, and the Ag crystals or
nano-particles were found in the shell region. These MCP micellar solutions also exhibited a
long period of thermodynamic stability.
2. Experimental
2-1 Synthesis of the PVAc-AgNO3 metal chelate polymer (MCP)
Two samples of PVAc-AgNO3 metal chelate polymer contained 0.5 wt% AgNO3 and 2.0
wt% AgNO3 with respect to the weight of PVAc, were prepared. For the 0.5 wt% AgNO3
MCP, a 25wt% solution of PVAc/formic acid formed by dissolving 25 g polyvinyl acetate
(Kanto Chemical Co., Japan) into 75 g formic acid (analytical grade from Nacalai Tesque Inc. ,
Japan), and an aqueous solution of silver nitrate formed by dissolving 0.124 g AgNO3
((Merck-Schuchardt Co., U.S.A.) into 5 ml distilled water were made. By blending the two
solutions and stirring at 40~50 ℃ in air for several hours, a mixture of PVAc-AgNO3
complex was formed. The mixture was then poured into a large amount of distilled water, and
precipitation of the MCP occurred. The MCP precipitate was filtered out by suction in a
Buchner Funnel, washed with distilled water, and dried in vacuum at 40℃ for 24 hours. For
the 2.0 wt% AgNO3 MCP, the foregoing procedure was repeated again except that 0.50 g
AgNO3 was used in forming the aqueous solution of silver nitrate.
2-2 Preparation of the PVAc-AgNO3 MCP films
Three grams of the prepared 0.5 wt% AgNO3 MCP precipitate was re-dissolved in 7 g
formic acid to form a 30 wt% MCP/formic acid solution. The solution was cast onto a clean
glass substrate and dried in an electric oven with forced ventilation at 80 ℃ for 25 minutes
to form a 0.5 wt% AgNO3 MCP film.
Likewise, the above procedure was repeated for preparation of the 2.0 wt% AgNO3 MCP
film. In addition, native PVAc film without AgNO3 was prepared as a blank sample. After
complete dryness, these MCP films were peeled off from the glass substrate and cut into slices
for XRD, FTIR and XPS analyses.
2-3 Preparation of PVAc-AgNO3 micellar specimens
one gram of the 30 wt% MCP/formic acid solution was added to 10 ml mixed solvent of
formic acid and water (1:1.2, V/V), and vigorously stirred for an hour to form a MCP micellar
solution with AgNO3 molarity of 8×10-4 M. A drop of the MCP micellar solution was then
placed on a formvar/carbon-coated copper grid for solvent evaporation to form a specimen for
TEM examination. Specimen of native PVAc solution was also prepared in the same way as a
blank sample for TEM analysis.
2-4 Instruments
X-ray Diffraction (XRD) analysis of the samples was carried out by a Mac Science MPX3
diffractometer using Cu Kα X-ray operated at 40kV and 30mA. The grazing incident angle
was of 2.0o and the scanning speed was 3o/min spanning from 20o to 80o. Fourier Transfer
infrared (FTIR) absorption spectra were recorded by a Perkin Elmer Paragon 500
spectrometer with resolution of 4cm-1.
X-ray Photoeletron Spectroscopy (XPS) was conducted by a Physical Electronic ESCA
PHI 1600 spectrometer using a Mg Kα X-ray source (hν=1253.6 eV) with take-off angle
54.7o in an ultra-high vacuum system in which the operation pressure was lower than 5×10-10
torr. The energy position of the detected peaks was calibrated by the position of the carbon 1s
peak of (C-C) and (C-H) fixed at 285.0 eV.
Before performing the transmission electron microscopy (TEM) analysis, the MCP micellar
solution was treated using an ultrasonic vibrator for 20 sec and then a drop of this solution
was placed on a formval/carbon-coated copper grid for complete vaporization of the solvent.
The dried specimens of the MCP micellar solutions were examined by a Zeiss 902A
transmission electron microscopy (TEM) operated at 80kV.
3.Results and Discussion
3-1 X-ray diffraction analysis
The X-ray diffraction spectra of native PVAc, 0.5 wt% AgNO3 MCP and 2.0 wt% AgNO3
MCP films are depicted in Fig. 1. As shown in Fig. 1(a), native PVAc is amorphous as
expected. In contrast, the diffraction peaks of Ag crystal, which has a face-centered cubic
structure, are readily identified for the 0.5 wt% AgNO3 MCP and 2.0 wt% AgNO3 MCP films
in Fig. 1(b) and (c). The intensity of the Ag diffraction peaks increases significantly with the
content of AgNO3. These results indicate that the Ag(I) complex ions in the MCP films were
reduced to form Ag metal crystals.
To understand the factors controlling the reduction of Ag(I) complex ions, the sample
preparation procedure was repeated but THF was used instead of the HCOOH solvent, to
prepare the PVAc/AgNO3/THF MCP and its films. The films made of the PVAc/AgNO3/THF
were found to have a XRD spectrum similar to Fig. 1(a), i.e. without any detectable
diffraction peak of Ag(0), which suggests that HCOOH played an important role in forming
the Ag(0) crystals.
To probe further in this point, this study also used poly(vinyl alcohol) (PVA), which
contains hydroxyl functional groups, as the polymer matrix for the MCP system, and pure
H2O replaces the HCOOH solvent to prepare the PVA/AgNO3/H2O MCP and its films. The
X-ray diffraction spectrum of the PVA/2.0 wt% AgNO3/H2O MCP film is shown in Fig. 2(a).
It can be seen that the metallic Ag(0) crystal diffraction peak is still absent, in other words, no
reduction occurred and the complexed Ag(I) ions remained in the oxidized state. However,
when 0.1 mole of formic acid was added to the PVA/AgNO3/H2O solution and stirred for
several hours, the prepared PVA/2.0wt% AgNO3/H2O/HCOOH film then exhibited diffraction
peaks of the metallic Ag(0) phase, as shown in Fig. 2(b).
The foregoing results clearly demonstrate that HCOOH helped to reduce the Ag(I) complex
ions to form the Ag(0) crystals. It follows that in the MCP system of PVAc/AgNO3/HCOOH,
the formic acid not only acted as a solvent to the PVAc polymer, but also acted as a reducing
agent to the Ag(I) ions.
The reduction of Ag(I) ions to form zerovalent Ag(0) crystals in the MCP system can be
described by the following equation [11-13]:
2Ag＋＋HCOOH→2Ag＋CO2＋2H＋
(1)
After complete reduction of all Ag(I) ions, the oxidation of formic acid in equation (1) would
be ceased.
3-2 FTIR spectrometry
Figure 3(a) shows the FTIR spectrum of native PVAc film. The bands and their
corresponding stretching frequencies are C-H at 2800-3000 cm-1, C=O at 1738 cm-1, C-O-C at
1241 cm-1 and CH-O at 1022 cm-1, and the bending frequencies of O-CO＋ are at 794 cm-1
and 605 cm-1 [14]. It is worth noting that the weak absorption band near 3500 cm-1 is due to
the O-H groups.
The FTIR spectrum of 0.5 wt% AgNO3 MCP film shown in Fig. 3(b) is similar to Fig. 3(a),
except the former has a broader and stronger O-H absorption band. It is reasonable to assume
that the treatment of PVAc polymer with silver nitrate had increased the amount of O-H
groups in the MCP film. These O-H species did not come from the water molecules, rather
originated from the hydrolysis of the polymer chains, for all the MCP films had been
desiccated in vacuum to remove water before carrying out the FTIR measurements.
3-3 X-ray photoelectron spectroscopy analysis
XPS measurements were performed to characterize the surface of the pure PVAc and the
MCP films. As shown in Fig.4, the XPS wide scan spectra indicates the main elements on the
surfaces of pure PVAc and MCP films were carbon and oxygen (no hydrogen was detected),
and it is evident that small amount of silver element existed on the surface of the MCP films.
The functional composition of the pure PVAc and MCP films can be determined from the
curve fitting of C1s core-level peaks, as shown in Fig. 5. Four different carbon functionalities
are considered: (1) hydrocarbon (C-H/C-C) at 285.0 eV; (2) methyl (CH3) at 285.7 eV; (3)
alcohol or ether (C-OH/C-O-C) at 286.6 eV; and (4) ester (O-C=O) at 289.15 eV [15,16]. In
Fig. 5(a), the peak area of the pure PVAc film has the hydrocarbon component comprised
82.86% of the C1s signal, which indicates the surface of pure PVAc film is almost the C-H
and C-C environments. After the silver nitrate was added to the PVAc matrix, the profile of
C1s line was altered, indicating that there was a change in the intensity of its four components,
as shown in Fig. 5(b) and (c). No extra C1s signature shifting could be resolved with the MCP
film, except the intensity of the C1s level associated with the alcohol and ester component
was increased. This shows that the proportion of oxygen-containing carbon on the surface of
MCP film is higher than that of the pure PVAc film.
The contribution of the different components of the total C1s core-level peaks is
summarized in Table I, and their peaks corresponding to different carbon and oxygen in the
polymer backbone structure are shown in scheme 1.
1
CH2
3
CH
O
1'
x
4
C
O
3'
1
CH2
2
CH3
3
CH
y
OH
2'
4'
Scheme 1. Schematic illustration of the different carbon (1, 2, 3 and 4) and oxygen (1’, 2’ ,
3’ and 4’ ) in the polymer backbone structure.
The O1s core-level peaks of pure PVAc and MCP films are shown in Fig.6. As resolved
by deconvolution, the O1s spectrum of pure PVAc consisted of three different oxygen
functionalities, the (1’) ester (C-O-C=O) at 533.8 eV; the (2’) alcohol (C-O-H) at 533.1 eV,
and the (3’) carbonyl (O-C=O) at 532.4 eV [17,18], as shown in Fig. 6(a). The O1s spectrum
of 0.5 wt% AgNO3 MCP film was broadened on the low-binding side by addition of one new
peaks (4’), as shown in Fig. 6(b).
In Fig. 6(b), the new peak is contributed by single-bonded oxygen interacted with silver, so
that the electron transfer from the silver to the oxygen led to a shifting in the O1s binding
energy. The new peak at 532.55 eV is due to the formation of hydroxyl-Ag (C-O(H)-Ag)
component, resulted from a shifting of the original peak of the hydroxyl groups from 533.1
eV to 532.55 eV (-0.55 eV). It is worth noting that in addition to the peaks contributed by the
four oxygen functionalities, another new peak at 531.8 eV appeared in the O1s spectrum of
2.0 wt% AgNO3 MCP film, as shown in Fig. 6(c). This new peak was contributed by the
inorganic oxides that resulted from the reaction between Ag(0) and the oxygen or water
molecules in the air. The O1s data are summarized in Table II.
Both the O1s spectrum and Table II data indicate that the increase in C-O contribution
being at the expense of C=O bonds. These results coincide with a decrease in the ester
moieties and the formation of alcohol groups. Furthermore, the C-O/C=O ratio increased
obviously from 6.45/46.78=0.14 (for the pure PVAc) to (20.87+5.22)/36.96=0.71 (for 0.5
wt% AgNO3 MCP).
These findings may be explained in relation to the hydrolysis of PVAc chains take place in
the MCP system, in which that the hydrophobic structure of PVAc chains was transformed
into a PVAc/PVOH structure with a higher water affinity. The hydrolysis of the ester groups
in the PVAc matrix was a function of the AgNO3 concentration, since the 2.0 wt% AgNO3
concentration gave a larger amount of hydroxyl groups in the polymer chains, that is, the
C-O/C=O ratio was increased to (24.59+14.24)/26.24=1.48.
From the above results, it is obvious that the MCP films contained more PVOH units in the
polymer chains than that of the pure PVAc film. The hydrolysis of PVAc polymer was
induced by the addition of aqueous AgNO3 solution as depicted in equation (2).
CH2
CH
O
CH2
x
C
CH
CH3
y
+
n
AgNO3/HCOOH
H2O
OH
O
CH2
CH
x-n
CH2
CH
y+n
+
n
CH3
C
OH
(2)
O
O
C
CH3
OH
O
The report that PVAc is liable to undergo hydrolysis under acidic or alkaline environment
until a new equilibrium is reached, as suggested in some literature [19,20], is consistent with
the foregoing results and equation (2).
3-4 TEM analysis
In the PVAc-AgNO3 MCP system, the MCP chains had been partially hydrolyzed to attain a
PVAc/PVOH structure. The PVOH part, which containing plentiful of hydroxyl groups, was
changed to hydrophilic but the PVAc part remained hydrophobic in nature. The hydrolyzed
MCP chains with PVAc/PVOH structure exhibited both the hydrophilic and hydrophobic
properties.
To understand the amphiphilic properties of the PVAc/PVOH structure, a 0.5 wt% AgNO3
MCP solution was dispersed into a mixed solvent of HCOOH/H2O, the morphologies of the
MCP micelles were then investigated by TEM.
It should be noted that MCP chains precipitate instantly in pure water, but in contrast
become thoroughly soluble in pure formic acid. Therefore the mixed solvent of formic
acid/water was used so that the hydrophobic moieties of the PVAc/PVOH structure were
swollen by the formic acid to avert precipitation.
After dispersed into the HCOOH/H2O solvent, the MCP chains underwent self-arranged to
realign the hydrophilic part outwards to contact the aqueous medium, while the hydrophobic
part was converged inwards to form the micelle core, and the resultant was a micellar solution
containing normal micelles of the MCP.
For comparison, a sample of native PVAc dispersed in HCOOH/H2O was prepared in light
of the process for MCP micellar solution described in section 2-3 of this paper. The TEM
photographs of this sample are shown in Fig. 7. Owing to the hydrophobic properties of pure
PVAc and the absence of assistant additives, such as surfantants, etc., the polymer was
difficult to disperse uniformly in the aqueous solution but tended to form droplet coagulation,
and the aggregates in Fig. 7(a) thus displayed variant diameters and irregular shapes. Fig. 7(b)
is a magnified image of the aggregates found in the system of Fig. 7(a), obviously the
micelles in these aggregates did not carry the core-shell structure.
The TEM images of the 0.5 wt% AgNO3 MCP dispersed into the HCOOH/H2O solvent are
shown in Fig. 8. In this well-stabilized micellar solution, the uniformly distributed micelles,
as shown in Fig. 8(a), were found to display a circular shape of size below 200nm.
Fig. 8(b) is an enlarged micrograph showing the Ag(0) metal crystal shell being carried by
the micelle found in Fig. 8(a). These zerovalent silvers had already incorporated with the
hydroxyl groups of the MCP so that when these hydrophilic groups realigned outwards to the
aqueous medium, the Ag(0) followed the pattern and arranged orderly outward to form the
micelle shell. As shown in Fig. 8(b), the Ag(0) metal crystal within the micelle underwent
nano-aggregation to form the Ag nano-particles of limited size. Fig. 8(c) is the TEM image
showing the selected area diffraction pattern of the Ag-containing micelle in Fig. 8(b).
Because of the high water affinity of their PVAc/PVOH structure, the MCP chains when
dispersed in the HCOOH/H2O solvent usually formed a uniform micellar solution, and in
which most micelles were found carrying the Ag-shell.
4. Conclusions
In this study, a silver-containing nanocomposite has been produced by PVAc-AgNO3 MCP
chemical process. The nanoscale silver particles were generated from its metal salts in the
solvent of formic acid without addition of other reducing agent, and the Ag(0) coordinated in
the polymer matrix with a homogeneous dispersion.
The chain structure of the polymer matrix was hydrolyzed to become a hybrid of
PVAc/PVOH structure, which showed an amphiliplic property and contained plentiful
hydroxyl groups capable of incorporating with the silver nanoparticles. In a formic acid
aqueous medium, the MCP chains self-arranged into polymer micelles with a morphology
having the hydrophilic PVOH, which interacted with the silver, on the outwards and the
hydrophobic PVAc on the inwards.
Although the morphologies displayed by most dried specimens were mainly of the core-Ag
shell shape, however, their shapes were found variable by changing the concentration of
AgNO3 added, or by altering the condition of solvent in the MCP micellar solution, and
relevant studies on these will be reported recently in our successive papers.
Acknowledgement
The authors would like to acknowledge the financial support of this research by the National
Science Council of Taiwan under contract No. 91-2216-E005-018.
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Figure caption
Figure 1. XRD spectra of (a) PVAc polymer, (b) 0.5 wt% AgNO3 MCP , and (c) 2.0 wt%
AgNO3 MCP films.
Figure 2. XRD spectra of PVA/2.0 wt% AgNO3 MCP films: (a) without HCOOH solvent, (b)
with HCOOH solvent added.
Figure 3. FTIR spectra of (a) PVAc polymer and (b) 0.5 wt% AgNO3 MCP films.
Figure 4. XPS survey spectra of (a) PVAc polymer, (b) 0.5 wt% AgNO3 MCP and (c) 2.0 wt%
AgNO3 MCP films.
Figure 5. C1s core-level spectra of (a) PVAc polymer, (b) 0.5 wt% AgNO3 MCP and (c) 2.0
wt% AgNO3 MCP films with fitted peaks.
Figure 6. O1s core-level spectra of (a) PVAc polymer, (b) 0.5 wt% AgNO3 MCP and (c) 2.0
wt% AgNO3 MCP films with fitted peaks.
Figure 7. TEM images of dried specimen of (a) PVAc/HCOOH system added with
HCOOH/H2O mixed solvent, cast on a formval/carbon-coated copper grid, and (b) magnified
image of (a).
Figure 8. TEM images of dried specimen of (a) 0.5 wt% AgNO3 MCP/HCOOH system added
with HCOOH/H2O mixed solvent, cast on a formval/carbon-coated copper grid, (b) magnified
image of (a), and (c) the SAD pattern of the polycrystalline Ag(0) in (b).
Figure 1
(a) PVAc polymer
Ag(111)
PVAc
(b) 0.5 wt% AgNO3
Intensity (Arb. Unit)
(c) 2.0 wt% AgNO3
Ag(200)
Ag(220)
Ag(311)
(c)
Ag(111)
(b)
(a)
10
20
30
40
50
2 Theta
60
70
80
Figure 2
(a) PVA/2.0 wt% AgNO3/H2O
(b) PVA/2.0 wt% AgNO3 /H2O/HCOOH
Intensity (Arb. Unit)
1200
Ag (111)
PVA
1100
1000
900
800
Ag (200)
(b)
Ag (220)
Ag (311)
700
600
500
400
300
200
(a)
100
0
10
20
30
40
2 Theta
50
60
70
80
Figure 3
1241
1738
0.0
1.0
C=O
(a) PVAc polymer
(b) 0.5 wt% AgNO3 MCP
C-O-C
1373
CH3
0.8
0.2
1022
Absorbance
CH-O
0.4
0.6
+
O-CO
O-H
0.6
0.4
3455
0.8
0.2
0.0
1.0
605
2800-3000
3520
C-H
794
(b)
(a)
4000
3500
3000
2500
2000
1500
-1
Wavenumber (cm )
1000
500
Intensity (Arb. Units)
Figure 4
C 1s
O 1s
(c) 2.0 wt%
Ag 3d5/2
(b) 0.5 wt%
Ag 3d3/2
(a) PVAc polymer
800
600
400
Binding Energy (eV)
200
Intensity (Arb. Units)
Figure 5
C 1s
(1)
(3)
(2)
(4)
292
290
288
286
284
282
280
278
280
278
280
278
Binding Energy (eV)
(a)
Intensity (Arb. Units)
C1s
(1)
(3)
(2)
(4)
292
290
288
286
284
282
Binding Energy
(b)
Intensity (Arb. Units)
C1s
(1)
292
(2)
(3)
(4)
290
288
286
284
282
Binding Energy (eV)
(c )
Intensity (Arb. Units)
Figure 6
O 1s
(3')
(1')
(2')
538
536
534
532
530
528
Binding Energy (eV)
(a)
Intensity (Arb. Units)
O 1s
(3')
(2')
(4')
(1')
538
536
534
532
530
528
Binding Energy (eV)
(b)
Intensity (Arb. Units)
O 1s
(3')
(2')
(4')
(5')
(1')
538
536
534
532
Binding Energy (eV)
(c )
530
528
Figure 7
400 nm
(a)
25 nm
(b)
Figure 8
300 nm
(a)
Ag
30 nm
(b)
Ag (111)
Ag (200)
Ag (220)
(c)
Table I. C1s binding energy (ev)a and relative peak area (%) of the fitted peaksb of PVAc
and MCP films.
Sample
(1)
(2)
(3)
(4)
hydrocarbon
methyl
alcohol/ether
ester
C-H/C-C
CH3
C-OH/C-O-C
O-C=O
285.00 eV
285.70 eV
286.60 eV
289.15 eV
Pure PVAc
Area (%)
82.86
5.30
6.54
5.30
70.83
8.27
12.62
8.28
10.24
18.59
10.24
0. 5wt% AgNO3 MCP
Area (%)
2.0wt% AgNO3 MCP
Area (%)
60.94
a: The binding energy ranges are + 0.2 eV.
b: FWHM = 1.4 eV; Lorentzian-Gaussion ratio = 50 %.
Table II. O1s binding energy (eV)a and relative peak area (%) of the fitted peaksb of PVAc
and MCP films.
(1’)
ester
C-O-C=O
Sample
533.80 eV
(2’)
(3’)
(4’)
(5’)
alcohol
carbonyl
alcohol-Ag
inorganic oxide
C-O-H
O-C=O
C-O(H)-Ag
Ag-O-Ag
533.10 eV
532.40 eV
532.55 eV
531.80 eV
Pure PVAc
Area (%)
46.77
6.45
46.78
---
---
36.96
20.87
36.96
5.22
---
26.24
24.59
26.24
0.5wt% AgNO3 MCP
Area (%)
2.0wt% AgNO3 MCP
Area (%)
14.24
a: The binding energy ranges are + 0.2 eV.
b: FWHM = 1.2 eV; Lorentzian-Gaussion ratio = 80 %.
8.70