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STUDIES OF STRUCTURAL, THERMAL, OPTICAL AND ELECTRICAL BEHAVIOUR OF CONDUCTING POLYMER
POLPYRROLE, POLYPYRROLE/ZEOLITE AND POLYPYRROLE/BISMUTH OXIDE CONJUGATED SYSTEMS
1 Department of Physics, Faculty of Science, Universiti Putra Malaysia, MALAYSIA2 Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, MALAYSIA
EMMA ZIEZIE MOHD TARMIZI Viva PhD presentation
PROF. DR. ZAINAL ABIDIN TALIB1, ASSOC. PROF. DR HALIMAH MOHAMED KAMARI1,PROF. ANUAR KASSIM2
Introduction of polymer, conducting polymer, Polypyrrole, Zeolite and Bismuth oxide
Applications
Objectives of the Study
Approaches & Research Methodology
Results and Discussion
PART 1 & 2 : Preparation of Samples
PART 3 & 4: Measurements: XRD, ED-XRF, FTIR, FESEM, DRS, Laser Flash, TGA, ESR & VDP
Conclusions
Research Contributions
PRESENTATION OVERVIEW
INTRODUCTION
Polymers are formed of a very large molecules (macromolecules) created by
polymerization of smaller subunits.
llustration of a Polypeptide macromolecule (Source: Wikipedia)
Polymers (or plastic) are known to have good insulating properties
Polymers are one of the most used materials in modern world. Their uses and
applications range from containers to clothing.
A. J. Heeger, Alan G. MacDiarmid, and Hideki Shirakawa
“for the discovery and development of electrically conductive polymers- polyacetylene”
Conductive Polymers
How can plastic become conductive? Plastics are polymers, molecules that form long chain repeating themselves like a
necklace.
In becoming electrically conductive, a polymer has to imitate a metal
its electron need to be free to move and not bound to the atoms.
Two conditions to become conductive:-
1.) the polymer must consists of alternating single & double bonds
In conjugation system, the bonds between the carbon atoms are alternately single and
double. Every bond contains a localised “sigma” (σ) bond which forms a strong chemical
bond. In addition, every double bond also contains a less strongly localised “pi” (π) bond
which is weaker.
Simplest chemical structure of Polyacetyelene with (Source: Nobelprize.org)
However this is not enough,
2.) the plastic has to be disturbed either by removing electron from (oxidation) or
inserting them into (reduction) the material. The process is known as Doping.
There are two types of doping:-
a.) p-doped (oxidation) – removing electron from its backbone, leaving hole in the form
of positive charge that can move along the chain.
b.) n-doped (reduction) – adding electron from its backbone
Changing the oxidation level of conjugated polymer means changing the number of the
electron on its backbone.
The game in the illustration above offers a simple model of a doped polymer. The
pieces cannot move unless there is at least one empty "hole". In the polymer each
piece is an electron that jumps to a hole vacated by another one. This creates a
movement along the molecule - an electric current.
NH
NH
NH
HN
HNN
HN
HN
NH
NH
HNN
HNN
+
+
Electron Acceptor
Electron Acceptor
polaron
bipolaron
HN
HNN
HN
Polaron and bipolaron formation on backbone of Polypyrrole.
Doping – Better Molecule Performance
Conductivity of conductive polymers compared to those of other materials, from quartz
(insulator) to copper (conductor).
Pyrrole
Pyrrole:
heterocyclic aromatic organic compound
a five-membered ring (formula molecule: C4H4NH)
high conductivity
can be prepared by various method such as chemical, electrochemical, vapor
phase, etc
various metallic salts have been employed to polymerize pyyrole :-
FeCl3, Fe(NO3)3, Fe(SO4)3 etc conductivity between 10-5- 200 Scm-1
Zeolite & Bismuth OxideZeolite are crystalline aluminosilicate minerals
Occurs naturally (volcanic rocks & ash layer react
with alkaline groundwater), also produced industrially
Contains various kinds of channel and cages with
different sizes and geometry
Widely use as sorbents, ion exchangers and catalyst
Bismuth (III) oxide is perhaps the most industrially important
compound of Bismuth
It has five crystallographic polymorph
Low toxicity & widespread use in pharmaceutical
Environmental friendly
High electrical conductivity, chemical stability
Solar cell
Liquid
Electrolyte
Rechargeable Batteries
Electrochromic
Display
Electrochemical Storage
Fuel cell
APPLICATIONS
Sensors
OBJECTIVES OF THE STUDY
To prepare an intrinsically conducting compound Polypyrrole through chemical oxidative polymerization method.
optimum ratio of oxidation/monomer, synthesis duration and polymerization conditions
To produce Polypyrrole/Zeolite and Polypyrrole/Bismuth oxide with optimal physical properties stability, morphology, thermal, opticcal and electrical responses.
To study the effect and response response between Zeolite which is microparticleand Bismuth oxide, a macroparticle with the host polymer at different concentrations.
To study the effect of Polypyrrole, Polypyrrole/Zeolite and Polypyrrole/Bismuth oxide intrinsically conducting polymer of different concentration levels and percentage of primary and secondary doping agents through various techniques:-a.) Fourier Transform Infrared (FTIR) Spectroscopyb.) Thermal Gravimetry Analysis (TGA)c.) X-Ray Diffraction (XRD)d.) Field Emission Scanning Electron Microscopy (FESEM)e.) Energy Dispersion X-Ray Flourescence (ED-XRF)
To investigate the temperature, current and applied voltage dependence on the thermal, magnetic and electrical properties of all samples using :a.) Laser Flash Techniqueb.) Electron Spin Resonance (ESR)c.) Van Der Pauw (VDP) method
To find correlation and possible applications of both systems.
Experimental design conducted in this research
Analysis Report WritingComputational
Study – ORIGIN &
EXCEL software
Polypyrrole/Zeolite Polypyrrole/Bismuth oxidePolypyrrole
Optimum ratio oxidation/monomer, synthesis duration & polymerization condition
to obtain good conductive sample
Measurements
Diffuse Reflectance Spectroscopy (DRS)
FESEMED-XRF
TGA
XRD
Morphology Studies
Preparation of sample for measurement
[Powder and Palletizing according to measurement]
Preparation of sample – Chemical oxidative polymerization menthod
Double distillation fo Pyrrole
Part 1
Part 2
Part 3
Part 4
FTIR
Temperature,Current & Voltage
Dependence StudiesLaser Flash ESR VDP
APPROACHES & RESEARCH METHODOLOGY
RESULTS & DISCUSSION
The optimum concentration of Pyrrole is 0.2 M
Water bath is needed during the stirring process to maintain the temperature of the
solution as increment temperature could cause to the failure of obtaining the
conductive sample
The optimum time for completing the polymerization process is 6 hours
7 tonne is the most favorable pressure value to form a good pellet
0 5 10 15 20 25 30 35 40
876543
Inte
nsi
ty (
a.u
.)
Diffraction angle (2
Zeolite
1 MR
1 MR 5%Z
1 MR 15%Z
1 MR 10%Z
1 MR 20%Z
1 2
0 5 10 15 20 25 30 35 40
Inte
nsi
ty (
a.u
.)
Diffraction angle (2
Bi2O
3
1 MR
1 MR 5%B
1 MR 15%B
1 MR 10%B
1 MR 20%B
431
2 6
5
RESULTS & DISCUSSION
The effect of (a) Zeolite and (b) Bismuth oxide on 1 MR Polypyrrole
All pristine Polypyrrole (only with the presence of primary doping agent) showing amorphous nature with a broad halo observed at
around 2 value of 25o.
Some degree of crystallinity is observed after introduction of Zeolite and Bismuth oxide as secondary doping agents in Polypyrrole
Zelite and Bismuth oxide overlapped the broad halo which indicate higher crystallinity of Polypyrrole/Zeolite and
Polypyrrole/Bismuth oxide
a b
RESULTS & DISCUSSION
Element(%)
Sample
Cl Fe Si Na K Al Mn
Zeolite - 19.017 33.102 23.257 20.460 1.659 0.722
1MR 96.415 1.015 - - - - -
1MR 5%Z 65.486 8.186 11.626 4.945 7.244 1.380 0.219
1MR 10%Z 46.716 12.915 19.617 8.045 9.328 1.853 0.356
1MR 15%Z 36.067 16.942 23.442 9.459 9.500 1.648 0.452
1MR 20%Z 26.772 18.929 30.327 7.658 10.582 1.910 0.509
Chlorine and iron arises from primary doping agent and confirmed the presence in every systems
Contents of Zeolite is observed
made up of silicate, natrium, kalium and iron
Zeolite presence is confirmed in each Polypyrrole/Zeolite samples
As Zeolite is increased, it is observed that chlorine content decreased
could be due to formation complex between chlorine and Zeolite (negatively-charge balance of the surface could have
replace the role of chlorine)
Elemental analysis of Polypyrrole and Polypyrrole/Zeolite.
Element(%)
Sample
Cl Fe Bi
Bismuth
oxide- - 99.800
1MR 96.415 1.015 -
1MR 5%B 27.577 0.629 70.103
1MR 10%B 22.212 0.798 76.438
1MR 15%B 15.652 0.538 81.348
1MR 20%B 14.446 0.485 83.916
RESULTS & DISCUSSION
Elemental analysis of Polypyrrole and Polypyrrole/Bismuth oxide.
Chlorine is observed in every samples of Polypyrrole/Bismuth
oxide
The presence of Bismuth is confirmed in every samples of
Polypyrrole/Bismuth oxide
Shows same mechanism as in Polypyrrole/Zeolite system
contents of iron and chlorine begin to fall-off
RESULTS & DISCUSSION
The successful of poly,erization of Polypyrrole,
Polypyrrole/Zeolite and Polypyrrole/Bismuth oxide is
confirmed as all the crucial bands were observed.
1600 1400 1200 1000 800 600 400
1 MR 20%Z
1 MR 15%Z
1 MR 10%Z
1 MR 5%Z
1 MR
Zeolite
Tra
nsm
itta
nce
(A
rb u
nit)
Wavenumber, cm-1
1536
14591298
1159 1016 879 759
667563
429
The FTIR spectra of 1 MR Polypyrrole and
Polypyrrole/Zeolite conjugated system.
Assignment
Wavenumber (cm-1)
pristine 5 wt% 10 wt% 15 wt% 20 wt%
v (C=C) of Pyrrole
(aromatic type)
1526 1533 1533 1534 1536
v (C-N) of Pyrrole 1446 1442 1446 1449 1459
v (C-C) of Pyrrole 1285 1293 1294 1295 1298
v (C-C) of Pyrrole /
vibarations of Zeolite
lattice
1140 1151 1152 1153 1159
δ (C-H) and δ (N-H)
of Pyrrole
1021 1028 1025 1025 1026
Assignments of FTIR absorption bands of 1 MR Polypyrrole (PPy) and
Polypyrrole/Zeolite conjugated system.
RESULTS & DISCUSSION
1600 1400 1200 1000 800 600 400
1 MR 15%B
1 MR 20%B
1 MR 10%B
1 MR 5%B
1 MR
Bi2O3
Wavenumber, cm-1
Tra
nsm
itta
nce
(A
rb u
nit)
1520 1443 1283 11321016
841 759656
589500 402
The FTIR spectra of 1 MR Polypyrrole and
Polypyrrole/Bismuth oxide conjugated system.
Assignment
Wavenumber (cm-1)
pristine 5 wt% 10 wt% 15 wt% 20 wt%
v (C=C) of Pyrrole
(aromatic type)
1526 1533 1533 1534 1536
v (C-N) of Pyrrole 1446 1442 1446 1449 1459
v (C-C) of Pyrrole 1285 1293 1294 1295 1298
v (C-C) of Pyrrole /
vibarations of Zeolite
lattice
1140 1151 1152 1153 1159
δ (C-H) and δ (N-H)
of Pyrrole
1021 1028 1025 1025 1026
Assignments of FTIR absorption bands of 1MR Polypyrrole (PPy)
and Polypyrrole/Bismuth oxide conjugated system.
Polymer identification through bonds and functional
groups present in the polymer
Crucial and major bands for all samples Polypyrrole,
Polypyrrole/Zeolite and Polypyrrole/Bismuth oxide
associated below 1600 cm-1.
RESULTS & DISCUSSION
aa b c
FESEM image of (a) 1 MR Polypyrrole and 20% of impregnanted (b) Zeolite & (c) Bismuth oxide in 1 MR Polypyrrole
Polypyrrole give globular or nodule morphology antwined
forming cauliflower like structures continously giving rise
to three dimensional structure.
Didn’t have any particular direction and appeared to be
connected to each other at variant angles.
Exhibit a denser and more compact morphology as
primary doping agent increased,
Zeolite exhibit a dense and more compact morphology.
Globular structure can be seen distributed throughout the
Zeolite external surface.
In case of Polypyrrole/Bismuth oxide, small round
particles as well as some particle pattern with diffrerent
dimension scattered in the system.
Higher concentrations of secondary dopi ng agent caused
the particle become smaller, compact, higher porosity and
surface area.
RESULTS & DISCUSSION
200 300 400 500 600 700 800 900 1000 1100 1200
50
60
70
80
90
100
110
1 MR
1 MR 15 % Z
1 MR 10 % Z
1 MR 5 % Z
Zeolite
Weig
ht (%
)
Temperature (K)
1 MR 20 % Z
TGA thermogram of 1 MR Polypyrrole and
Polypyrrole/Zeolite conjugated system.
Pristine 1 MR Polypyrrole shows first significant
weight loss as early as 326 K with weight loss of
5.416%
3 stages of weight loss observed with total
weight loss of 51.250 %
Pure Zeolite only recorded one stage of weight loss at
427 K with a total weight loss of 12.590 %
1 MR Ppy with 20% Zeolite shown lowest weight loss
Samples Step 1
293-403 K
Weight loss
(%)
Step 2
404-663 K
Weight loss
(%)
Step 3
664-1173 K
Weight loss
(%)
Total
weight loss
(%)
Zeolite -Tmax=427 K
12.590-
12.590
1 MR PPy
Tmax=326 K
5.416
Tmax= oC
Tmax=459 K
7.342 38.492 51.250
1 MR PPy 5 %
Zeolite
Tmax=328 K
4.742
Tmax=471 K
9.104 22.691 36.537
1 MR PPy 10
% Zeolite
Tmax=330 K
7.398
Tmax=558 K
10.508 21.110 39.016
1 MR PPy 15
% Zeolite
Tmax=337 K
9.372 25.589 - 34.961
1 MR PPy 20
% Zeolite
Tmax=329 K
3.747 22.593 - 26.700
TGA data for Polypyrrole and Polypyrrole/Zeolite conjugated systems.
200 300 400 500 600 700 800 900 1000 1100 1200
20
30
40
50
60
70
80
90
100
110
Temperature (K)
Weig
ht (%
)
1 MR 20 % B
Bi2O
3
1 MR 15 % B1 MR
1 MR 5 % B
1 MR 10 % B
RESULTS & DISCUSSION
TGA thermogram of 1 MR Polypyrrole and
Polypyrrole/Bismuth oxide conjugated system.
Samples
Step 1
293-403 K
Weight loss
(%)
Step 2
404-663 K
Weight loss
(%)
Step 3
664-1173 K
Weight loss
(%)
Total
weight
loss
(%)
Bismuth oxide -
Tmax=538K
0.466
Tmax=757 K
0.660
Tmax=633 K
0.9182.044
1 MR PPy
Tmax=326 K
5.416
Tmax= oC
Tmax=459 K
7.342 38.492 51.250
1 MR PPy 5 %
Bismuth oxide
Tmax=346 K
6.160
Tmax= oC
Tmax=610 K
9.110
Tmax=797 K
64.460 79.730
1 MR PPy
20 % Bismuth
oxide
Tmax=347 K
0.920
Tmax=735 K
31.720
- 18.000 50.640
TGA data for Polypyrrole and Polypyrrole/Bismuth oxide conjugated
systems.
Raw Bismuth oxide starts to decompose at 538 K
with0.466 % loss
The decomposition of Polypyrrole/Bismuth oxide
occurs in multiple stages.
In Polypyrrole/Bismuth oxide, the intercalation of 20%
shows the lowest weight loss of 50.640 %
Overall, Zeolite shown the lower weight loss while
Bismuth oxide stable up to higher decompostion
temperatutre
RESULTS & DISCUSSION
300 320 340 360 380 400 420
0.8
1.0
1.2
1.4
1.6
1.8
2.0
The
rmal
diff
usiv
ity,
x10
-7(m
2 s-1)
Temperature (K)
1 MR
1 MR 5 % Z
1 MR 10 % Z
1 MR 15 % Z
1 MR 20 % Z
Thermal diffusivity of 1 MR Polypyrrole as a function of
Zeolite concentration at different temperature.
300 320 340 360 380 400 420
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
The
rmal
diff
usiv
ity,
x10
-7(m
2 s-1)
Temperature (K)
1 MR
1 MR 5 % B
1 MR 10 % B
1 MR 15% B
1 MR 20 % B
Thermal diffusivity of 1 MR Polypyrrole as a function of
Bismuth oxide concentration at different temperature.
T1 structure scattering (due to defect from blend)
T2 microvoids (vacant-site scattering)
T2T1 T1 T2
Thermal diffusivity of all samples shows a similar temperature
dependence.
For each samples there are two temperature regions were
observed T1 (slight increase of thermal diffusivity
with temperature) & T2 (thermal diffusivity fall-off or levelling-
off with temperature)
In the case of pristine Polypyrrole, it is believed that the primary
doping agent has increased the conjugation length which provide
more through-space pathways for electron to migrate.
Zeolite and Bismuth oxide have enhanced thermal properties of
Polypyrrole by forming a stronger bonding.
It is believed also that higher thermal diffusivity coming from
higher molecular weight due to larger interaction between chain
molecules. (i.e 20% of Zeolite in 1 MR Polypyrrole and 20%
Bismuth oxide 3 MR Polypyrrole)
RESULTS & DISCUSSIONA
bso
rba
nce
(a
.u)
1 MR
1 MR 5% Z
1 MR 20% Z
1 MR 5% B
1 MR 20% B
UV-VIS-NIR absorption spectra of Polypyrrole (a)
pristine 1 MR (b) doped 5 % Zeolite (c) doped 20 %
Zeolite (d) doped 5 % Bismuth oxide (e) doped 20%
Bismuth oxide.
Sample
Absorption peak position (eV)
Bipolaron Polaron
1 MR 1.393 2.061 3.450 -
1 MR 5% Zeolite 1.393 2.061 3.552 -
1 MR 20% Zeolite 1.393 2.165 3.663 -
1 MR 5% Bismuth
oxide
1.389 2.007 3.831 -
1 MR 20%
Bismuth oxide
1.396 - 3.806 4.474
Absorption peak position of Polypyrrole, Polypyrrole/Zeolite and
Polypyrrole/Bismuth oxide.
Absorption peak is the indicative of the nature charge carriers
(i.e. polaron or bipolarons).
All samples of Polypyrrole and Polypyrrole/Zeolite and
Polypyrrole/Bismuth oxide at lower doping concentration
exhibit three absorption peak which corresponds to transition
bonding to antibonding polaron and bipolaron and
interband transition of the system.
At higher concentration of Bismuth oxide another peak arise
at higher photon energy is believed associated states induced
by interaction between Polypyrrole and Bismuth oxide.
1.0 1.5 2.0 2.5 3.0 3.5 4.0
0
50
100
150
200
250
300
350
Eg = 2.147 eV
Photon energy (eV)
[F(R
h
3 MR
RESULTS & DISCUSSION
Kubelka-Munk transformed reflectance
spectra of pristine Polypyrrole 3 MR
conjugated systems
0
50
100
150
200
250
[F
(Rh
Eg = 2.080 eV
3 MR5% Z
0
25
50
75
100
125
150
Eg = 1.780 eV
3 MR 20% Z
1.0 1.5 2.0 2.5 3.0 3.5 4.0
0
1000
2000
3000
4000
5000
6000
Photon energy,h (eV)
[F(R
h
3 MR 5% B
Eg = 1.942 eV
1.0 1.5 2.0 2.5 3.0 3.5 4.0
0
500
1000
1500
2000
2500
3000
3500
4000
Photon energy,h (eV)
Eg = 1.911 eV
3 MR 20% B
Kubelka-Munk transformed reflectance spectra of 3 MR Polypyrrole with
(a) 5 % Zeolite (b) 10 % Zeolite, (c) 5 % Bismuth oxide, and (d) 20 %
Bismuth oxide.
DRS is a good technique in enhancing the
scattering in powder material since its more
easier, efficient and believed to be more accurate
compare as it involved cumulative of multiple
reflection.
Kubelka-Munk treatment is used by extrapolating
linear part of the plot to obatin the energy gap
RESULTS & DISCUSSION
Sample Energy gap, Eg (eV)
3 MR 2.147
3 MR 5% Zeolite 2.080
3 MR 20% Zeolite 1.780
3 MR 5% Bismuth oxide 1.942
3 MR 20% Bismuth
oxide
1.911
Energy gap, Eg values for Polypyrrole,
Polypyrrole/Zeolite and Polypyrrole/Bismuth
oxide conjugated systems obtained from Kubelka-
Munk treatment.
It is oberved that both primary and secondary doping agents of
FeCl3, Zeolite and Bismuth oxide, band structure can be changed.
In this work, highest primary doping agent plus highest concentrations of
secondary doping agents have shown to give a small energy gap.
All the samples is suggested behavior of semiconductor
Overall with 20 % of Zeolite in 3 MR Polypyrrole have shown to have a
small energy gap that is 1.780 eV
RESULTS & DISCUSSION
1 MR 5 % Z
1 MR 20 % Z
1 MR
ES
R in
ten
sity
(a.u
.)
ES
R in
tens
ity (
a.u.
)
1 MR
1 MR 5 % B
1 MR 20 % B
In this work, ESR has been used as an additional technique to probe the presence of carrying species /free radical.
Pristine Polypyrrole of 1 MR shows a symmetric single-line ESR signal. This is similar to ESR signal observed at lower
concentrations of Zeolite and Bismuth oxide which suggest the polarons in the samples.
At higher concentration of secondary doping agents, the ESR signal become broader compared to pristne Polypyrrole and
lower concentrations of primary doping agents. This broad component is belived to be more easily saturated than narrow
component and this could be showing that the sample having evolution from polaron to bipolaron.
The ESR spectra of Polypyrrole doped with 5% and 20%
of Zeolite in 1 MR Polypyrrole at room temperature.
The ESR spectra of Polypyrrole doped with 5% and 20%
of Bismuth oxide in 1 MR Polypyrrole at room
temperature.
RESULTS & DISCUSSION
Sample g-values
3 MR 1.9951
3 MR 5% Zeolite 1.9973
3 MR 20% Zeolite 2.1818
3 MR 5% Bismuth oxide 1.9908
3 MR 20% Bismuth
oxide
1.9670
g-values for Polypyrrole, Polypyrrole/Zeolite and
Polypyrrole/Bismuth oxide conjugated systems obtained
from ESR measurement at room temperature.
g-value which is expressed as a function of microwave frequency and
outer magnetic field at resonance provide the information regarding the
electronic structure.
In this work, all the samples generate g-value that is closed to free
electron which is 2.002322. This observation is typical in conductive
polymer and confirmed the resonance comes from the electron
delocalized in the -system of the carbon atoms (polaron).
RESULTS & DISCUSSION
0 50 100 150 200 250 300
0.0
0.5
1.0
1.5
2.0
2.5
Temperature (K)
Co
nd
uct
ivity
(S
/cm
)
1 MR
1 MR 5 % Z
1 MR 20 % Z
0 50 100 150 200 250 300
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
Temperature (K)
Co
nd
uct
ivity
(S
/cm
)
1 MR
1 MR 5 % B
1 MR 20 % B
SampleElectrical Conductivity,
Scm-1
1 MR 2.000x10-2
1 MR 5% Zeolite 8.605x10-1
1 MR 20% Zeolite 2.400
1 MR 5% Bismuth oxide 9.650x10-2
1 MR 20% Bismuth oxide 2.967x10-1
Experimental values of the room temperature electrical conductivity, , for
Polypyrrole, Polypyrrole/Zeolite and Polypyrrole/Bismuth oxide conjugated
systems.
The temperature dependence of conductivity for 1 MR pristine
Polypyrrole and Polypyrrole with impregnation of 5 wt% and 20
wt% of Zeolite from 20 K to 300 K.
The temperature dependence of conductivity for 1 MR pristine
Polypyrrole and Polypyrrole with impregnation of 5 wt% and 20
wt% of Bismuth oxide from 20 K to 300 K.
It is observed that the introduction of primary and secondary doping
agents, increased the conductivity of Polypyrrole.
However it is believed that at lower concentrations, the polaron occupy
random positions between the chains and cause to have low mobility.
This could be also due to midgap in the energy between polaron bands
is large which act as resistance for electron to hop from one band to
another which resulted in low conductivity.
As the doping agents in increased, more polaronare obtained and
hence a bipolaron is released. At this point, more polarons is formed
and narrower the midgap thus ease the electron to hop
conductivity increased.
RESULTS & DISCUSSION
0.25 0.30 0.35 0.40 0.45
-2
-1
0
1
LnS
cm-1)
T-1/4
(K-1/4
)
1 MR 5 % Z
1 MR 20 % Z
Plot of Ln versus T-1/4 of 1 MR Polypyrrole
with impregnation of 5 wt% and 20 wt% of
Zeolite.
0.20 0.25 0.30 0.35 0.40 0.45 0.50
-5
-4
-3
-2
-1
LnS
cm-1)
T-1/4
(K-1/4
)
1 MR 5 % B
1 MR 20 % B
Plot of Ln versus T-1/4 of 1 MR Polypyrrole with
impregnation of 5 wt% and 20 wt% of Bismuth oxide.
0.25 0.30 0.35 0.40 0.45 0.50
-6
-5
-4
-3
-2
1 MR
2 MR
3 MR
LnS
cm-1)
T-1/4
(K-1/4
)
Plot of Ln versus T-1/4 of 1 MR, 2 MR, 3
MR pristine Polypyrrole conjugated
systems.
Several models have been used to explain conductivity behaviour in the
polymers ( i.e. Arrhenius model).
Finally, it is found that Mott’s law for variable range hopping is
mechanism that is found suitable to describe the conductivity for
conjugated system.
After finalizing the plot of 1-D, 2-D, and 3-D VRH, it can be concluded
that 3D-VRH model is the most suitable for explaining the conduction
mechanism wherein the charge transport occurs by phonon assisted by
thermally jumps between localized site.
Polypyrrole, Polypyrrole/Zeolite and Polypyrrole/Bismuth oxide have beensuccessfully prepared usinh chemical oxidative polymerization technique.
Pristine Polypyrrole of 1 , 2 and 3 MR are mainly amorphous in naturewhile the presence of Zeolite and Bismuth oxide has introduced somedegree of crystallinity. Thus, more ordered structure is formed.
Thermal properties in terms of thermal stability and thermal diffusivity havebeen enhanced with the presence of both secondary doping agents.
The optical and electrical studies on the Polypyrrole, polypyrrole/Zeoliteand Polypyrrole/Bismuth oxide conjugated systems revealed the enhancedelectrical properties of the systems in the presence or certain amount ofZeolite and Bismuth oxide.
CONCLUSIONS
Improved thermal properties of Polypyrrole conjugated systems with thepresence of Zeolite and Bismuth oxide
Improved optical and electrical properties of Polypyrrole conjugated system through introduction of inorganic secondary doping agents.
Providing the thermal diffusivity approach for Polypyrrole, Polypyrrole/Zeoliteand Polypyrrole/Bismuth oxide conjugated systems.
RESEARCH CONTRIBUTIONS
Supervisory committee; Prof Dr Zainal Abidin Talib, Assoc. Prof Dr HalimahKamari, Prof Dr Anuar Kassim
Labmates 201, Physics & Chemistry Department, UPM
Staff, Physics & Chemistry Departments, UPM
Family and friends!
ACKNOWLEDGEMENTS