Studies on N-alkylated Polyaniline and its application to ...
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Studies on N-alkylatedPolyaniline and its
application to measurementof hydrogen peroxyde at
neutral pHDiego L. Raffa1, K. Tong Leung2, Fernando Battaglini1
1 Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires2 Department of Chemistry, University of Waterloo
Redox and Acid-Base Equilibria of Polyaniline
NH
NH
NH
NH
N
N N
N
NH
NH
N
N
NH
NH
N+
H
N+
H
A-
A-
2A- -2e -2A- -2e
2A- +2H+
Insulating
Insulating
Conducting
How to use it in Sensors
i
time
C4C3C2C1
C1<C2<C3<C4
GOxPoly(o-phenylendiamine)
PANI
Carbon Electrodes
HRP
V
POLYMER
CARBON BAND
INSULATOR
Examples
P. N. Bartlett y P. R. Birkin; Synthetic Metals, 61 (1993) 15-21 P. N. Bartlett; P. R. Birkin; J.H Wang; F. Palmisano; G. De
Benedetto; Anal.Chem. 1998, 70, 3685-3694.
Attempt to improve the problem of pH
•Polymerization in presence of PSS orPVS•A Donnan potential that keeps positiveions in the film is created
Results:•The polymer conductivity is temporarily improved at pHs between 6 and 7•After some minutes, conductivity decreases and is only recovered by immersion in acid
Our Attempt: Sultonation
NH
NH
NH
NH
n
¨¨
¨¨
OS
OO
+
NH
NH
NH
n
N
SO3-
XPS Analysisx 102
50
60
70
80
90
100
CPS
410 408 406 404 402 400 398 396 394 392 390Binding Energy (eV)
x 102
40
50
60
70
80
90
CPS
410 408 406 404 402 400 398 396 394 392 390Binding Energy (eV)
Before After
N1S
190
200
210
220
CPS
N1S
160
165
170
CPS
N1S.DTS
x 102
160
170
180
406 404 402 400 398 396 394Binding Energy (eV)
N1S.DTS
x 102
150
155
406 404 402 400 398 396 394Binding Energy (eV)
3 hs room T overnight room TN1S.DTS
N1S
x 102
140
145
150
155
160
165
170
175
180
185
CPS
406 404 402 400 398 396 394Binding Energy (eV)
N1S.DTS
N1S
x 102
160
165
170
175
180
185
190
195
CPS
406 404 402 400 398 396 394Binding Energy (eV)
3 hs 60ºC overnight 60ºC
Electrochemistry results
-70
-50
-30
-10
10
30
50
70
90
110
-0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50E vs Ag|AgCl/V
i/A
H2SO4 1,8 M, 50 mVs-1
Electrochemistry results
-70-60-50-40-30-20-10
0102030405060
-0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50E vs Ag|AgCl/V
i/A
Buffer acetic 0,1 M; pH 4,7; 50 mVs-1
Electrochemistry results
-8-7-6-5-4-3-2-1012345678
-0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50E vs Ag|AgCl/V
i/A
Buffer PIPES 50 mM; KNO3 0,1 M; pH 7; 50 mVs-1
Results of Resistance measurements
Resistance of PANI y PSPANI on a switch electrode.
1,3x1041,1x107Buffer PIPES pH 7
1,9x1034,1x104Buffer acetic0,1 M pH 4,7
1,7x1031,7x103H2SO4 1,8 M
R de PSPANI [Ω]
R de PANI [Ω]
Media
Sensor based on PSPANI and HRP
PSPANICarbon Electrodes
p-phenylendiamine
HRP or MP-11
Works at pH 7!!
Results for HRP (current curves)
iDrain vs t de switch de PAni sultonada a T amb. con HRP o MP-11 inmovilizada con p-fenilendiamina. HEPES 0,1 M KNO3 0,1 M pH 7
(EDrain=20 mV)(EGate=0 V vs Ag/AgCl) Se agregó a t=~50 s H2O2 hasta llegar a la concentración correspondiente
0
2
4
6
8
10
12
0 100 200 300 400 500 600 700 800
t [s]
i [A]
0,1 mM HRP
0,2 mM HRP
0,3 mM HRP
0,5 mM HRP
1 mM HRP
Results for MP-11 (current curves)
iDrain vs t de switch de PAni sultonada a T amb. con MP-11 inmovilizada con p-fenilendiamina. HEPES 0,1 M KNO3 0,1 M pH 7
(EDrain=20 mV)(EGate=0 V vs Ag/AgCl) Se agregó a t=~50 s H2O2 hasta llegar a la concentración correspondiente
0
2
4
6
8
0 100 200 300 400 500 600 700 800
t [s]
i [A]
0,025 micro
0,05 micro
0,1 micro
0,2 micro
0,3 micro
0,5 micro
1 micro
Calibration Curve for: MP-11
Velocidad máxima normalizada de switch de PAni sultonada una noche a T amb. con microperoxidasa MP-11 inmovilizada
con p-fenilendiamina. MOPSs 0,05 M KNO3 0,1 M pH 7 (EDrain=20 mV)(EGate=0 V vs Ag/AgCl) vs Concentración
y = -0.0377xR2 = 0.9776
-4.00E-02
-3.50E-02
-3.00E-02
-2.50E-02
-2.00E-02
-1.50E-02
-1.00E-02
-5.00E-03
0.00E+00
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Concentración [mM]
Velo
cida
d m
áx
norm
aliz
ada[1
/s]
Calibration Curve for: MP-11
Taking slope of the first seconds as criterion
Pendiente de los 1° segundos de switch de PAni sultonada una noche a T amb. con microperoxidasa MP-11 inmovilizada con p-
fenilendiamina. MOPSs 0,05 M KNO3 0,1 M pH 7 (EDrain=20 mV)(EGate=0 V vs Ag/AgCl) vs Concentración
y = -0.2432x + 0.0066R2 = 0.9893
-2.50E-01
-2.00E-01
-1.50E-01
-1.00E-01
-5.00E-02
0.00E+00
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Concentración [mM]
Pend
ient
e de
los
1°
seg.
[ µA/
s]
Conclusions:
•Certain independence between conductivity of PANI and pH can be achieved•The procedure can be made simple and fast by changing reaction temperature and time
•A working pH of 7 can be achieved forsensors based on PANI•Analysis time is still too long and must be shortened to optimize the method
Acknowledgement:
•CONICET•Fundación Antorchas
•DQIA y QF-INQUIMAE•Lab group for making me feel at home
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