UNIVERSITI PUTRA MALAYSIA

PREPARATION AND CHARACTERIZATION OF POLYPYRROLE/MONTMORILLONITE CLAY CONDUCTING POLYMER

FARIZ BIN ADZMI

FS 2007 45

PREPARATION AND CHARACTERIZATION OF POLYPYRROLE/MONTMORILLONITE CLAY CONDUCTING POLYMER

FARIZ BIN ADZMI

MASTER OF SCIENCE

2007

1

PREPARATION AND CHARACTERIZATION OF POLYPYRROLE/MONTMORILLONITE CLAY CONDUCTING POLYMER

By

FARIZ BIN ADZMI

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirement for the

Degree of Master of Science

January 2007

2

Abstract of thesis to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science

PREPARATION AND CHARACTERIZATION OF POLYPYRROLE/MONTMORILLONITE CLAY CONDUCTING POLYMER

By

FARIZ BIN ADZMI

January 2007

Chairman: Professor Anuar Kassim, PhD Faculty: Science In this study, Ppy/MMT nanocomposites have been prepared by polymerization of

pyrrole in the presence of FeCl3 as oxidation agent and MMT clay in aqueous medium

through the chemical polymerization.

The electrical conductivity of the Ppy/MMT nanocomposites was measured by using

four-point probe technique. Conductivity of the Ppy/MMT nanocomposites increased

from 0.45 to 2.25 S/cm. The increase of conductivity depended on the percentages of

Ppy loading in the nanocomposites. Ppy/MMT nanocomposites exhibited similar infra-

red (IR) absorption peaks as Ppy and MMT clay. Thereby, confirming the presence of

the Ppy and MMT in the products. The X-Ray Diffraction (XRD) patterns revealed,

MMT strong peak at 2θ = 6.68º (d-spacing 13.22 Å) and for Ppy/MMT

nanocomposites is at 2θ = 4.92º (d-spacing 17.94 Å). The shifting of the angle 2θ is

indicated that the insertion of Ppy has occurred. As determined from XRD analyses the

crystalline size of MMT is 17.31 Å and is 25.42 Å for Ppy/MMT nanocomposites.

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Thermal gravimetric analysis (TGA) revealed the improvement of degradation

temperature of Ppy is at 157.36 to 177.21 ºC for Ppy/MMT nanocomposites. Scanning

electron micrographs (SEM) revealed some interesting morphological differences

between the pure MMT clay and Ppy/MMT nanocomposites. The Ppy/MMT

nanocomposite exhibits a denser and more compact morphology. Particle formation of

irregular and smaller size was clearly revealed by SEM.

The effects of several parameters in producing Ppy/MMT nanocomposites were also

studied. When percentage of MMT was increased from 1 to 7% the conductivity was

decreased from 2.25 to 0.38 S/cm. Result shows higher conductivity for sample

prepared at low temperature (~5ºC) compared to room temperature (25ºC). The surface

morphology of the Ppy/MMT nanocomposites at low temperature is more compact and

denser compared to Ppy/MMT nanocomposites prepared at room temperature. FeCl3 is

the suitable oxidation agent to produce Ppy/MMT nanocomposites in aqueous medium.

While 6 hours is the suitable preparation time for completion of polymerization of

pyrrole.

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Abstrak yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains

PENYEDIAAN DAN PENCIRIAN TERHADAP POLIPIROL/MONTMORILLONITE KLAY POLIMER PENGALIR

Oleh

FARIZ BIN ADZMI

Januari 2007

Pengerusi: Professor Anuar Kassim, PhD Fakulti: Sains Dalam kajian ini, Ppy/MMT nanokomposit telah dihasilkan melalui proses

pempolimeran pirol dengan menggunakan FeCl3 sebagai agen pengoksidaan dan MMT

klay dalam larutan akueus melalui proses pempolimeran kimia.

Keberaliran elektrik bahan Ppy/MMT nanokomposit ini diukur menggunakan teknik

prob empat titik. Didapati keberaliran bahan nanokomposit ini bertambah daripada 0.45

kepada 2.25 S/cm. Pertambahan keberaliran ini bergantung kepada peratusan polipirol

masuk ke dalam bahan Ppy/MMT nanokomposit. Ppy/MMT nanokomposit

menunjukkan penyerapan sinar infra merah (IR) sama dengan penyerapan di dalam

polipirol dan MMT klay. Ini membuktikan kewujudan polipirol dan MMT klay di

dalam Ppy/MMT nanokomposit. Paten pembelauan sinar-X (XRD) menunjukkan

puncak penyerapan tajam MMT klay pada 2θ = 6.68º (jarak-d 13.22 Å). Manakala

bagi Ppy/MMT pada pada 2θ = 4.92º (jarak-d 17.94 Å). Perubahan pada sudut 2θ

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menunjukkan kemasukkan polimer polipirol ke dalam dalam MMT klay. Saiz hablur

untuk MMT adalah 19.31 Å, manakala untuk Ppy/MMT nanokomposit adalah 25.42Å.

Analisis terma gravimetri (TGA) telah menunjukkan peningkatan suhu degradasi

daripada 157.36ºC untuk polipirol kepada 177.21ºC untuk Ppy/MMT nanokomposit.

Analisis mikroskop pengimbas electron (SEM) menunjukkan keadaan permukaan yang

berbeza diantara MMT and Ppy/MMT nanokomposit. Ia telah menujukkan permukaan

Ppy/MMT nanokomposit adalah padat dan rapat. Formasi partikel adalah tidak sekata

dan bersaiz kecil dapat dilihat dengan jelas.

Kajian ini juga mengkaji kesan-kesan dan faktor-faktor lain yang mempengaruhi

penghasilan Ppy/MMT nanokomposit. Apabila peratusan MMT ditingkatkan daripada 1

kepada 7% didapati keberaliran Ppy/MMT nanokomposit semakin menurun daripada

2.25 kepada 0.38 S/cm. Kajian menunjukkan keberaliran pasa suhu rendah (~5ºC)

adalah lebih tinggi darapada suhu bilik (25ºC). Perbezaan juga terdapat dalam

morfologi permukaan Ppy/MMT nanokomposit di mana pada suhu rendah permukaan

Ppy/MMT nanokomposit menjadi semakin padat dan rapat. Seterusnya FeCl3 adalah

agen pengoksidaan yang paling sesuai digunakan untuk penghasilan Ppy/MMT dalam

medium akueus. Sementara 6 jam adalah masa yang sesuai untuk melengkapkan proses

pempolimeran pirol.

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ACKNOWLEDGEMENTS

Alhamdulillah to Almighty God. First and foremost, I would like to express my deepest appreciation to my supervisor,

Prof. Dr. Anuar Kassim and members of the committee, Prof. Dr. Zulkarnain Zainal and

Assoc. Prof. Dr. Mohamad Zaki Ab Rahman for their guidance, advice and suggestion

throughout the duration of this study.

I would like to extend my tremendous thanks and greatest gratitude to the lecturers and

supported staff at Chemistry Department especially to Mr. Abas, Mr. Khidir, Mr Nordin

and others who have directly or indirectly contributed their part. My sincere thanks also

to my laboratory mate Mr. Ikramul, Mrs. Rozita, Ayu and Shidat. I’m also very thankful

to the financial support from MARA.

My special thanks to my parent Adzmi b. Othman and Maznah bt. Yaacob for their

support and encourage.

Last but not least, I’m also indebted to my beloved friends Norhafeza, Khairul, Pian, Itha,

Ezamy and others, whose friendship I’ll forever treasure.

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This thesis submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfillment of the requirement for the degree of Master of Science. The members of the supervisory committee are follows: Anuar Kassim, Ph. D. Professor Chemistry Department Faculty of Science Universiti Putra Malaysia (Chairman) Zulkarnain Zainal, Ph. D. Professor Chemistry Department Faculty of Science Universiti Putra Malaysia (Member) Mohamad Zaki Ab Rahman, Ph. D. Associate Professor Chemistry Department Faculty of Science Universiti Putra Malaysia (Member)

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DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that is has not been previously or concurrently submitted for any degree at UPM or other institutions. FARIZ BIN ADZMI Date: 23 April 2007

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TABLE OF CONTENTS

Page ABSTRACT 2 ABSTRAK 4 ACKNOWLEDGEMENTS 6 APPROVAL 7 DECLARATION 8 LIST OF TABLES 11 LIST OF FIGURES 13 LIST OF ABBREVIATIONS 15 CHAPTER

I INTRODUCTION

Background Conducting Polymer

17 19

Problems Statement Objectives of the Study

22 23

II LITERATURE REVIEW Polypyrrole

Properties of Polypyrrole Montmorillonite Clay

The Structure Physical Properties

Polymer Nanocomposites Polypyrrole/montmorillonite Nanocomposites Polypyrrole/Al2O3 Nanocomposites Polypyrrole/zeolite Nanocomposites Polypyrrole/Fe3O4 Nanocomposites

Epoxy-clay Nanocomposites Polyurethane-clay Nanocomposites Polypropylene-clay Hybrids Polystyrene-clay Nanocomposites Rubber-clay Hybrids Applications

24 26

35 36 38 39 40 41 41 41 42 42 43 44 45

III MATERIALS AND METHODS Chemicals

Experimental Effect of the Concentration Oxidant and Pyrrole Effect of Percentage MMT Effect of Temperature Effect of Oxidant

46

46 47 48 48

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Effect of Preparation Time Characterization Methods

Electrical Conductivity Measurement X-ray Diffraction Analysis (XRD) Analysis of Surface Area and Porousimetry (ASAP) Fourier Transfer Infrared Spectroscopy (FTIR) Scanning Electron Microscopy (SEM) Thermal Gravimetric Analysis (TGA)

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48 49 50 50 51 52

IV RESULTS AND DISCUSSION Conductivity Measurement

Effect of Concentration FeCl3 and Pyrrole Effect of Percentage MMT Effect of Preparation Temperature Effect of Preparation Time Effect of Temperature

X-Ray Diffraction Analysis (XRD)

Effect of Percentage MMT Effect of Preparation Temperature Effect of Oxidant

Scanning Electron Microscopy (SEM)

Effect of Percentage MMT Effect of Preparation Temperature

Fourier Transfer Infrared Spectroscopy (FTIR) Thermal Gravimetric analysis (TGA)

Effect of Percentage MMT Effect of Preparation Temperature

Surface Area and Porosity Analysis (ASAP)

54 56 58 58 58 61 65 68 70 71 73 75 76 81 84 87 89

V

CONCLUSION AND RECOMMENDATION

Conclusion Recommendations

92 93

REFERENCES APPENDICES BIODATA OF THE AUTHOR

PUBLICATIONS CONFERENCE AND SEMINAR

94 99 101 102 103

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LIST OF TABLES

Table Page

1 Typical conducting polymer structure. 20

2 Properties changes typically observed upon electrical stimulation to switch conducting polymer between oxidized and reduce state.

21

3 The mole ratio of FeCl3 and pyrrole monomer. 47

4 Preparation of samples for characterization method. 53

5 The conductivity of the Ppy/MMT nanocomposites by increasing concentration of FeCl3 with fix concentration of pyrrole (0.1M) monomer and percentage of MMT (1%).

55

6 The conductivity of the Ppy/MMT nanocomposites by increasing concentration of pyrrole monomer with fix concentration of FeCl3 (0.1M) and percentage of MMT (1%).

56

7 The conductivity of Ppy/MMT nanocomposites by increasing percentage of MMT with fix concentration of pyrrole monomer (0.1 M) and FeCl3 (0.4 M).

57

8

The conductivity of Ppy/MMT nanocomposites prepared in different preparation temperature contains 1% of MMT, 0.1 M pyrrole and 0.4 M FeCl3.

59

9 The conductivity of Ppy/MMT nanocomposites against temperature. 60

10 XRD analysis for Ppy/MMT by increasing the percentage amount of MMT.

67

11 XRD observation for Ppy/MMT nanocomposites prepared at different temperature.

68

12 Assignment of FTIR absorption bands of Ppy, MMT and Ppy/MMT nanocomposites.

79

13 TGA analysis for Ppy, MMT, Ppy/MMT nanocomposites. 83

14 TGA analysis for pure Ppy, pure MMT and Ppy/MMT (contain 1% - 7% of MMT).

85

12

15 alysis for Ppy/MMT nanocomposites with different preparation temperature.

87

13

LIST OF FIGURES

Figure Page

1 Number of scientific papers published and patents issued in the area of conducting polymers for the past 25 years.

18

2 Scientific papers published on conducting polymers in the last 10 years categorized into various topics.

18

3 Polypyrrole formation. 26

4 Variation of tensile properties of Ppy film with phthalate concentration. 34

5 Variation of tensile properties of Ppy/PTS with applied potential. 34

6 Crystalline structure of montmorillonite showing intermeller water layers.

35

7 The conductivity of Ppy/MMT nanocomposites at different temperature. 61

8 XRD pattern for Ppy, MMT and Ppy/MMT nanocomposites. 63

9 Insertion Ppy in the MMT and expanding of d-spacing. 64

10 XRD pattern for Ppy/MMT nanocomposites by increasing percentage of MMT.

66

11 XRD pattern for Ppy/MMT nanocomposites prepared at different temperature.

69

12 XRD pattern for PpyMMT nanocomposites with different oxidant. 70

13a SEM micrograph of MMT. 72

13b SEM micrograph of Ppy. 72

13c SEM micrograph of Ppy/MMT nanocomposites. 73

14a SEM micrograph of Ppy/MMT nanocomposites with 3% of MMT. 74

14b SEM micrograph of Ppy/MMT nanocomposites with 5% of MMT. 74

14c SEM micrograph of Ppy/MMT nanocomposites with 7% of MMT. 75

14

15 SEM micrograph of Ppy/MMT nanocomposites low temperature of

preparation (~5ºC).

76

16 The FTIR spectra for pure MMT, pure Ppy and Ppy/MMT nanocomposites.

77

17 FTIR spectrum for Ppy/MMT nanocomposites with different percentage of MMT.

80

18 TGA and DTA analysis for (a) Ppy (b) MMT and (c) Ppy/MMT nanocompoosites.

82

19 TGA and DTA analysis for Ppy/MMT nanocomposites with increasing amount of MMT (from 1% to 7%).

86

20 TGA and DTA of Ppy/MMT nanocomposites with different of preparation temperature between room temperature and low temperature (ºC).

88

21a Hysteresis loops of pure MMT. 90

21b Hysteresis loops of Ppy/MMT nanocomposites. 90

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LIST OF ABBREVIATIONS ASAP Analysis of surface area and porosity

ATBN Acrylonitrile copolymer BNSA 5-buthylnaphthalene CSA Camphor sulfonic acid D/M Dopant/monomer

DMAC Dimethylacemide FTIR Fourier transfer infrared spectroscopy MBSA ρ-methylbenzenes sulfonic acid MMT Montmorillonite

NaANS Sodium alkylnaphthalene sulfonate NaDES Sodium alkylsulfonate NSA β-naphthalene O/M Oxidant/monomer

Ppy Polypyrrole

Ppy/MMT Polypyrrole/montmorillonite nanocomposites

PTS Polytoluene sulfonic RIA Relative humidity SEM Scanning electron microscopy

Tg Glass transition temperature TGA Thermal gravimetric analyses

XRD X-ray diffraction spectroscopy

ESR Electron spin resonance

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VRH Variable range hopping

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CHAPTER I

INTRODUCTION

Background

Since their discovery in the mid-1970’s, conducting polymers have been a hot research

area for many academic institutions. This research has supported the industrial

development of conducting polymer products and provided the fundamental

understanding of the chemistry, physics and materials science of these materials. The

impact of the field on science in general was recognized in 2000 by the awarding of

Nobel Prize for Chemistry to the three discoverer of conducting polymer: Alan

MacDiarmid, Alan Heeger and Hiderki Shirakawa.

A research over the past 25 years shows the levels of publications increasing rapidly after

1980 (Figure 1). The data suggest a peak in patenting in the late 1980’s, while the rate of

scientific publications increases unabated through the end of the 1990’s. At the present

time, around 40 new journal articles related to the conducting polymer are published

every week.

Figure 2 shows the main areas of interest of the paper published on conducting

polymer. With almost half of the publications related to the synthesis of

conducting polymer. The next largest area of research has been into the physic

conduction mechanism, while application for conducting polymer account for

fewer than 20% of publication.

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Figure 1: Number of scientific papers published and patents issued in the area of

conducting polymers for the past 25 years (Gordon et al., 2003).

Figure 2: Scientific papers published on conducting polymers in the last 10 tears categorized into various topics (Gordon et al., 2003).

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Conducting Polymer

It is possible to create conducting polymers with a diverse range of properties. For

example, chemical properties can be manipulated to produce materials capable of

trapping simple anions or to render them bioactive. Electrical properties can also be

manipulated to produce materials with different conductivities and different redox

properties. After synthesis, the properties of these fascinating structures can be

manipulated further through redox processes. The application of electrical stimuli can

result in drastic changes in the chemical, electrical and mechanical properties in

conducting polymers. These complex properties can be controlled only if we understand,

first the nature of processes that regulate them during the synthesis of the conducting

polymers, and second, the extent to which these properties are changed by the application

of an electrical stimulus.

Conducting polymers have emerged as one of most popular in materials science research.

It has all the desirable properties:

• They are readily engineered at the molecular level to recognize specific stimuli.

• Because they are conductive, they are facilitating transport of electrical

information.

A wide range of conducting polymers is shown in Table 1.

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Conducting polymers are of class of materials that are, no doubt, destined to play a major

role in intelligent materials science. As outlined in the reminder of this text, the properties

of these materials are versatile.

Table 1: Typical conducting polymer structures. Name Structure Polypyrrole (Ppy)

NH

* *n

S* *n

Polythiophene (PTh)

NH* *n

Polyaniline (PAn)

* *n Poly(para-phenylene) (PPP)

**n

Poly(phenylene-vinylene) (PPV)

S ** n Poly(phenylenesulfide) (PPP)

Poly(phenylene ethylene) (PPE)

* *n

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Table 2 shows the properties of conducting polymer and their behavior that can be

manipulated in situ using appropriate electronic stimuli.

Table 2: Property changes typically observed upon electrical stimulation to switch conducting polymer between oxidized and reduced states.

Property Typical Change Potential Application Conductivity From 10-7 to 103 S/cm Electronic components,

Sensors

Volume 3% Electromechanical actuators

Color 300-nm shift in absorbance Displays, smart windows

band

Mechanical Ductile-brittle transition

Ion permeability From zero to 10-8 molcm-2s-1 Membranes

in solution

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Problems Statement

Poor processibility of polypyrrole (Ppy) due to its insolubility and infusibility has

retarded further investigation on the structure and structure-physical properties. To

improve the processibility, many researches have been engaged in the development of

soluble or swollen Ppy and dispersible fine-powdered Ppy. At the same time, the electric

properties and/or stability of chemically prepared Ppy have also been investigated at

many laboratories because the stability of conducting polymers seems to be the main

limiting factor in their practical applications.

In recent years, composites of a special category, terms “nanocomposites” have been

studied with growing interest. For example Ppy base zeolite and Ppy base alumina

nanocomposites have extensively study due to improve the processibility of the Ppy and

enhance the mechanical properties of Ppy (Zhang et al., 1997).

In this presence of study the Ppy/MMT nanocomposites has been prepared through the

chemical polymerization by using FeCl3 as the oxidation agent for polymerization of

pyrrole in aqueous medium. The nanocomposites prepared are characterized in chemical

and physical properties.

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Objectives of the Study

This thesis presents and discusses the result of series experimental and analyses study of

physical and chemical characteristic of polypyrrole/montmorillonite (Ppy/MMT)

nanocomposites.

To achieve this aim, the following objectives are proposed:

1. To prepare and characterize the Ppy/MMT nanocomposites.

2. To study the effect of parameter such as concentration of pyrrole and FeCl3,

increasing percentage of MMT, oxidant used, preparation temperature and time of

preparation on Ppy/MMT nanocomposites.

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