a 10-a editie a seminarului national de nanostiinta si nanotehnologie 18 mai 2011 biblioteca...
Post on 27-Mar-2015
222 Views
Preview:
TRANSCRIPT
A 10-a editie a Seminarului National de nanostiinta si nanotehnologie
18 mai 2011 Biblioteca Academiei Romane
NATIONAL INSTITUTE OF MATERIALS PHYSICS BUCHAREST-MAGURELE
Atomistilor Str. 105 bis, P.O. Box MG-7, 077125 Magurele-Ilfov, Romania
Phone: +40(0)21 3690185, Fax: +40(0)21 3690177, email: barac@infim.ro, http://www.infim.ro
Composite materials based on carbon nanotubes and poly o-phenylenediamine
M. Baibarac*, I. Baltog, I. Smaranda, M.Scocioreanu, I. Gontia, T. Velula, L. Mihut
Abstract
The chemical polymerization of o-phenylenediamine (OPD) on single-walled carbon nanotubes (SWCNTs) in the presence of phosphomolybdic acid (H3PMo12O40 xH2O) has been studied by surface enhanced resonant Raman scattering (SERRS) spectroscopy. One demonstrates that an organic–inorganic hybrid composite of the type poly(o-phenylenediamine)/polyoxometallate-functionalized SWCNTs is produced by the chemical interaction between polyoxometallate-functionalized SWCNTs and poly(ophenylenediamine) (POPD) doped with [H2PMo12O40] ions. According to TEM investigations, a result of the chemical interaction of SWCNT with H3PMo12O40 xH2O is the formation into the composite mass of tube fragments of shorter length, which behave like closed shell fullerenes since and for these the Raman fingerprint is given by lines situated at 240–275 and 1450–1472 cm-1. The chemical polymerization of OPD on SWCNTs achieved in the absence of H3PMo12O40 xH2O leads to a covalent functionalization of the wall side of the tubes, which is revealed in Raman spectra at the excitation wavelength of 514 nm by an enhancement of the lines associated with the tangential vibrational modes of SWCNTs. Using FTIR spectroscopy, significant hindrance steric effects are evidenced in the POPD/polyoxometallate- functionalized SWCNT composite.
Experimental
☛ The chemical interaction of SWCNTs with H3PMo12O40 xH2O was studied using the mixture of the two constituents in the weight ratios of 0.1/5 and 0.01/5. After the interaction of the two constituents, a washing with water was carried out to eliminate un-reacted H3PMo12O40. The final product obtained by a drying until constant mass corresponds to SWCNTs doped with anions of H3PMo12O40. Solutions of SWCNTs doped with anions of H3PMo12O40 in CH3CN of 0.1% concentration were used to prepare films deposited on the rough Au support to be studied by SERS spectroscopy. The chemical synthesis of the hybrid material POPD/polyoxometallate-functionalized SWCNTs was carried out by direct addition of 1 g OPD to 5 g H3PMo12O40 + 0.1 g SWCNT or 5 g H3PMo12O40 + 0.01 g SWCNTs.In the absence of H3PMo12O40, the chemical polymerization of OPD was carried out according to the method was reported ,which involves the use of 0.09 g OPD dissolved in 20 ml of water and 2.34 ml of 0.71 M ferric chloride. To obtain the POPD/ SWNTs composites. Finally, both POPD and the POPD/SWCNTs composites were washed several times with water and dried in vacuum at 50oC for 24 h. For SERS studies were used films deposited onto rough Au supports . They were obtained from were obtained by the evaporation of the solvent using solutions of POPD and POPD/SWCNTs in CH3CN of 0.1% concentration ,
☛ Raman spectra were recorded at room temperature in a backscattering geometry under excitation wavelengths of 514.5 and 676.4 nm with a Jobin Yvon T64000 Raman spectrophotometer .
☛ FTIR spectra were obtained in the 400–4000 cm-1 range with a 4 cm-1 resolution, using a FTIR Bruker spectrophotometer, Vertex 70 model.
Results and Discussions
CONCLUSIONS
This paper reports new results obtained by surface enhanced Raman scattering (SERS) studies
on the chemical polymerization of OPD in the presence of SWCNTs and H3PMo12O40 xH2O.
The following results may be highlighted: (i) the chemical interaction of SWCNTs with
H3PMo12O40 xH2O leads to the formation of the polyoxometallate-functionalized SWCNTs; (ii)
the chemical polymerization of OPD in the presence of FeCl3 and SWCNTs leads to POPD
covalently functionalized SWCNTs composite characterized by a significant increase in
intensity of the Raman lines with maximum at 1536 and 1565 cm-1; this behavior permits to
conclude that a functionalization of the side-wall of the tubes with polymer took place; (iii) the
chemical polymerization of OPD in the presence of SWCNTs and H3PMo12O40 xH2O leads to
the formation of an organic–inorganic hybrid composite of the type SWCNTs functionalized
with POPD doped with [H2PMo12O40]- ions and tube fragments of shorter length like closed
shell fullerenes functionalized with POPD; (iv) the SERS spectrum of tube fragments of
shorter length like closed shell fullerenes functionalized with POPD, is characterized by new
Raman lines situated at ca. 240– 275 and 1450–1472 cm-1 .
1200 1300 1440 1520 1600
1200 1300 1440 1520 1600
1200 1300 1440 1520 1600
1465
1320
1543
1518 1541
1563
1588
1588
b
1330
1561 1584
1610
No
rma
lize
d R
am
an
in
ten
sit
y
c
1590
1324
1544
1568
1590
a
Wavenumber (cm-1)
Fig.2. SERS specra at exc=647 nm of films of SWCNTs in their initial state (a, curve black) and polyoxometallate-functionalized SWCNTs obtained fromthe chemical interaction of 0.1g SWCNTs+5gH3PMo12O40xH2O(curve red) and
0.01g SWCNTs+5gH3PMo12O40xH2O (curve green).The curve blue (c) shows the Raman
spectrum of poly-oxometallate-functionalized SWCNTs sample interacted with 1M NH4OH
Fig. 1. SERS spectra recorded at exc=514 nm of films of SWCNTs in their initial state (curve 1), polyoxometallate-functionalized SWCNTs
obtained from the chemical interaction between 0.1 g SWCNTs + 5 g H3PMo12O40 xH2O
(curve 2) and 0.01 g SWCNT + 5 g H3PMo12O40 xH2O (curve 3).
Curve 4 shows the Raman spectrum of the polyoxometallate-functionalized SWCNT sample
interacted with 1M NH4OH solution.
1200 1350 1500 1550 1600 1650150 200
4
3
2
1
1340
1340
1593
1587 1593
Wavenumbers (cm-1)
156
4 x 0.8
168
170
165
3 x 0.32 x 0.6
1
170
156
Nor
mal
ized
Ram
an I
nte
nsi
ty
600 700 800 900 1000 1100 1200
a)
1090
852
980
1063
963
869
791
762 852 947
990
1047
1225
1230
1212
1090
3
2
41
Ab
so
rban
ce (
a.u
.)
Wavenumbers (cm-1)
Fig.3.FTIR spectra of SWCNTSs (curve 1a),H3PMo12O40xH2O(curve3a),polyoxometallate-functionalized SWCNTs (curve 2a) and the polyoxometallate-functionalized SWCNTs
sample interacted with a 1 M NH4OH solution (4a).
-1600 -1200 -2000
60
120
200 1200 16000
6000
12000
-1600 -1400 -12000
200
400
600
800
1200 1400 16000
2000
4000
6000
8000
1000 1200 1400 16000
1000
2000
-134
0
-156
9
a1
-170-1595
Ram
an In
ten
sity
a2
170
1340
1569
1594
b1
-159
5-1
569
-140
7-1
377
-135
0-1
322
-124
6
b2
1247
1370
1324
1409
1531
1569
1595
1578
1526
1488
1406
1368
1248
1154
c1
Wavenumbers (cm-1)
Fig. 4. SERS spectra recorded at λexc = 514 nm of the SWCNTs in their initial state (a1,a2), POPD covalently functionalized SWCNTs
(b1,b2) and POPD (c1).
Fig. 5. HRTEM picture of POPD covalent functionalized SWCNTs.
-1600 -1400 -1200 -200 -1000
125
250
100 200 1200 1400 16000
2500
5000
-1600 -1400 -1200 -200 -1000
10
20
30
100 200 1200 1400 16000
200
400
600
Wavenumbers (cm-1)
Ram
an in
ten
sity
(ar
b.u
nit
s)
-155
8
-168
-159
3
a1
168 13
621558
1593
a2
-155
8
-136
1-1
420
-1591
-165
b1
1420
1558
1591
1245
1361
b2
Fig. 6. SERS spectra recorded at λexc = 514 nm of the SWCNTs functionalized with POPD doped
with [H2PMo12O40] - ions obtained by the chemical polymerization of 1g ODP +
5g H3PMo12O40 xH2O in the presence of 0.1g (a1, a2) and 0.01 g SWCNT (b1, b2).
100 200 3000
100
200
300
1000 1200 1400 1600 18000
600
1200
1800
2400
16
8
240
275
172
Wavenumber (cm-1)
Ram
an in
tens
ity (a
rb.u
nits
)
c
b
a
1367
1152 12
55
1472
1157
1222 12
6013
1513
5914
5014
86
1590
1543
1590
Fig. 7. SERS spectra recorded at λexc =647nm of SWCNT (curve a), the composite based
on SWCNTs functionalized with POPD doped with [H2PMo12O40]- ions and tube fragments of shorter length like closed
shell fullerenes functionalized with POPD (curve b) and POPD (curve c).
SWCNT functionalized with POPD doped
with [H2PMo12O40]- ions.: ☛
top related