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Although polymer and carbon-black composites are versatile, relatively inexpensive, and permanently conductive, there are several disadvantages related to the use of carbon black. The possibility of contamination of clean-room environments by shedding of carbon particles, a process known as sloughing, makes it unusable in many areas. Also, the level of conductivity for a particular resin is hard to control because of the steepness of the percolation curve (Figure 2- 25). Thereby, resistivity levels ranging from 10 6 to 10 9 Ω are hard to reach, and also other conductivity values are not completely reproducible. 2.3.1.2 Intrinsically Conductive Polymers Applications of conductive polymers have been extended during the last years, with the emphasis being to make better, smaller and faster electronic instruments. A few years ago, semiconductor silicon was the only material used to fabricate almost all electronic devices. Around 16 million bits of information can be stored by an advanced silicon chip in an area of less than 1 cm 2 , although a practical limit to the density of stored information in a chip exists. With further decreasing of the size, overheating occurs and electronic components do not work properly. To overcome this limitation, it has been suggested to use conductive polymers as a conventional semiconductor. Moreover, polymers have the advantages of flexibility, lightweight, high chemical inertness, corrosion resistivity, and ease of processing. Intrinsically conductive polymers have caused a dramatic change in polymer architecture. A key property of a conductive polymer is the presence of conjugated double bonds along the backbone of the polymer. A regular chemical bond (C–C) occurs when two atoms share a pair of electrons. Such sharing of electrons allows atoms to bind together and keeps molecules from flying apart. A double bond denoted as (C=C) occurs when the atoms share an extra pair of electrons. Conjugation occurs when there are single and double bonds alternating along the polymer chain in a π-conjugated system of the conductive polymers(Gerard, Chaubey, & Malhotra, 2002; Inzelt, Pineri, Schultze, & Vorotyntsev, 2000; Pron & Rannou, 2002). Consequently, electrically conducting polymers are composed of macromolecules having fully conjugated sequences of double bonds along the chains. It implies that in intrinsically conductive polymers, the polymer 56
chain provides the conductive path for the electrons. π-electrons are responsible for the unusual electronic properties of these polymers, such as low ionization potential, low energy optical transition, electron conductivity and high electron affinity. The conductivity of a polymer can be significantly increased by doping it with oxidative/reductive substituents or by donor/acceptor radicals. For example, Shirakawa et al. reported a conductivity increase of 9 to 13 orders of magnitude for doped polyacetylene (PA). Doping inorganic materials such as silicon involves substitution of atoms and is completely different from doping organic polymers. Conductive polymers are doped with oxidizing or reducing agents and chemicals that remove electrons from or add electrons to the polymer. A simple explanation is that the oxidation or reduction changes the electronic structure of the polymer so that it can conduct electricity. The degree of conductivity in the doping process is related to many factors, including the polymeric structure, degree of doping, and type of dopant. The “doped” form of polyacetylene had a conductivity of 10 5 Siemens per meter, which was higher than that of any previously known polymer. As a comparison, silver and copper have conductivity of 10 8 S m –1 . One of the most important domains still at the foreground of research activity in electrochemistry is preparation, characterization and application of electrochemically active, electronically conducting polymeric systems. From a practical standpoint, the first generation of intrinsically conductive polymers did not achieve great commercial success. These polymers tended to be insoluble, unprocessable, and extremely sensitive to environmental conditions. The genesis of the field can be traced back to the mid 1970’s when polyacetylene was reportedly prepared by accident by Shirakawa(Ito, Shirakawa, & Ikeda, 1996) as the first polymer capable of conducting electricity. Polythiazyl (SN)x discovered in 1975, was one of the pioneering conjugated polymers which showed conductivity around 0.29 K(Greene, Street, & Suter, 1975). Shirakawa et al.(Shirakawa, Louis, MacDiarmid, Chiang, & Heeger, 1977) in 1977 established the idea of using polymers for electrical conducting goals when the iodine-doped transpolyacetylene, (CH)x, exhibited a conductivity of 10 3 S/cm. After the appearance of the first organic conductive materials, other conducting polymers were synthesized, such as polyaniline (PANI), polypyrrole (PPY), poly p-phenylene (PPP), polythiophene (PT), and polyfuran (PFU), which are shown in Figure 2-26. Researchers started to work in this area and could tune the 57
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© Sepehr Ravati, 2010. UNIVERSITÉ
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DEDICATED To my parents iii
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RÉSUMÉ Cette thèse présente, po
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devenir une structure hiérarchique
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ABSTRACT This thesis presents, for
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system can be increased from 10 -15
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CONDENSÉ EN FRANÇAIS Dans ce trav
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deuxième coquille de PS. Les phase
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structures à percolation multiple
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autre sous-type de morphologie dans
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TABLE OF CONTENTS DEDICATION.......
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xxiii 2.4.1.1.1 Charged Polymer Ads
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5.3.4 Annealing Test ..............
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xxvii REFERENCES ..................
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LIST OF FIGURES xxix Figure 1-1. a)
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Figure 2-12. SEM photomicrograph of
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Figure 2-34. Schematic view of diff
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Figure 4-8. SEM micrographs of vari
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Figure 5-6. a),b) Scanning electron
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and c) triangular concentration dia
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n number of moles p concentration o
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AFM atomic force microscopy LIST OF
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PS-co-PMMA copolymer of PS and PMMA
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1.1 Introduction CHAPTER 1 - INTROD
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Figure 1-2. Human heart, longitudin
Page 51 and 52: One of the applications for porous
Page 53 and 54: On the other hand, a novel tri-cont
Page 55 and 56: 2.1 Polymer Blends CHAPTER 2 - LITE
Page 57 and 58: Based on Sterling’s approximation
Page 59 and 60: Antonoff’s rule (Equation 2-13) i
Page 61 and 62: 2.1.2.1 Binary Polymer Blends 2.1.2
Page 63 and 64: Some other studies(Everaert, Aerts,
Page 65 and 66: where the parameter z is dependent
Page 67 and 68: “compatibilization” was suggest
Page 69 and 70: a) λ BC A and B are matrices, b) C
Page 71 and 72: Reignier & Favis, 2000, 2003a; Reig
Page 73 and 74: measure the interfacial tension of
Page 75 and 76: a) b) Figure 2-6. Dependence of the
Page 77 and 78: Omonov et al. found double percolat
Page 79 and 80: 2.1.2.2.3 Effect of Composition on
Page 81 and 82: a) b) C B A c) Figure 2-12. SEM pho
Page 83 and 84: In the case where PS is the matrix,
Page 85 and 86: Posthuma de Boer, 1999) (Kumin & Ch
Page 87 and 88: lattice, such as square lattice, wi
Page 89 and 90: magnetization, which is a function
Page 91 and 92: Polymers have long been thought of
Page 93 and 94: epoxy as a function of nanotube wei
Page 95 and 96: Figure 2-19. Approaching the percol
Page 97 and 98: Figure 2-21. Transmission electron
Page 99 and 100: Figure 2-22: Dependence of PE conti
Page 101: Figure 2-24. Plot of the total numb
Page 105 and 106: 2.3.1.2.1 Polyaniline One of the mo
Page 107 and 108: CoPA/LLDPE/PANI blend and a poor-qu
Page 109 and 110: Narkis and co-workers extended and
Page 111 and 112: Figure 2-31: Conductivity of PVDF/P
Page 113 and 114: organic thin films, a novel and str
Page 115 and 116: on the topic have been reported in
Page 117 and 118: succeeded in creating thin films wi
Page 119 and 120: Addition of salt to the solution of
Page 121 and 122: different from that of linear homop
Page 123 and 124: Figure 2-39. Macromolecule with a)
Page 125 and 126: polyanion such as hyaluronan (HA)(P
Page 127 and 128: 2.4.1.1.7 Effect of Salt on Multila
Page 129 and 130: 2.4.1.1.8 Overcompensation of the M
Page 131 and 132: important factors determining the g
Page 133 and 134: As shown in Figure 2-44, swelling a
Page 135 and 136: increasing the pH value due to a de
Page 137 and 138: CHAPTER 3 - ORGANIZATION OF THE ART
Page 139 and 140: discussed above, HDPE, PS, PMMA, an
Page 141 and 142: CHAPTER 4 - LOW PERCOLATION THRESHO
Page 143 and 144: or model which predicts where the p
Page 145 and 146: concentration threshold for the ons
Page 147 and 148: chemical and weathering resistance,
Page 149 and 150: Table 4-1. Material Characteristics
Page 151 and 152: filled with blend pellets. To facil
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4.3.6 Conductivity Measurements DC
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experimentally in this research gro
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a) b) c) d) Figure 4-4. Schematic i
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microstructure of the quaternary bl
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a) b) c) d) Figure 4-6. SEM microgr
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a) b) PVDF PS PMMA c) d) e) HDPE PS
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Uniform layers of PS and PMMA situa
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the concentration of HDPE is increa
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a) b) c) e) Figure 4-11. SEM microg
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melt-processable and contains 25 wt
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One question that should be address
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Conductivity(S/cm) Ternary Blend 1,
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phase(PMMA), the concentration of P
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(6) Virgilio, N.; Desjardins, P.; L
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ONION MORPHOLOGY HDPE PVDF PS Contr
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work described above has focused on
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thermodynamic explanation to predic
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four-point probe increases continuo
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in the rheology tests were compress
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5.3.6 Layer-by-Layer Deposition The
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prepare a polymer blend structure w
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a) b) c) Figure 5-3. Scanning elect
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spontaneously self-assembled. After
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a) b) c) d) e) f) g) h) Figure 5-5.
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Since the ultra-low surface area va
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c) a) b) Figure 5-6. a),b) Scanning
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salt to a PSS polyelectrolyte solut
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A relationship between macropore si
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close together. It is interesting t
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Figure 5-9. Mass increase (%) indic
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In this work the conductance of the
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deposited PANI layers increases unt
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(52) Guo, H. F.; Packirisamy, S.; G
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6.2 Introduction It is well-known t
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modified version of Harkins theory(
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6.3 Experimental 6.3.1 Materials Co
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Complex voscosity (Pa.s) 1,0E+04 1,
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6.3.5.2 Focused Ion Beam (FIB) and
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a) c) b) d) e) f) PMMA PMMA HDPE HD
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y Harkins theory, PS will always si
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a) b) c) d) e) f) PS Figure 6-6. a)
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a) b) HDPE : black PS : grey PMMA :
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6.4.6 Continuity, Co-continuity, an
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c) V III II I VII I IV VI Figure 6-
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Continuity Scheme (a) Figure 6-10.
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Addition of a low concentration of
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Addition of small amounts of HDPE t
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icontinuous network with the HDPE.
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Three examples are shown in Figure
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(9) Mekhilef, N.; Verhoogt, H. Poly
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structures are formed due to the co
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CONCLUSION AND RECOMMENDATIONS In t
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REFERENCES A. K. Gupta, K. R. S. (1
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Caruso, F. (2003). Hollow Inorganic
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Domenech, S. C., Bortoluzzi, J. H.,
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Geuskens, G., Gielens, J. L., Geshe
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Hou, S., Harrell, C. C., Trofin, L.
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Krass, H., Papastavrou, G., & Kurth
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Macdiarmid, A. G., Jin-Chih, C., Ha
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Niziol, J., & Laska, J. (1999). Con
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Reghu, M., Yoon, C. O., Yang, C. Y.
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Shirakawa, H., Louis, E. L., MacDia
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Utracki, L. A. (1991). On the visco
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Yasuda, K., Armstrong, R., & Cohen,
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literature has examined factors inf
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(Reignier & Favis, 2000, 2003a; Rei
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Table A-1.2. Interfacial tensions a
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acquisition of images with a very h
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Table A-1.3. Continuity of the PMMA
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(17) Reignier, J.; Favis, B. D., Ma
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PANI. Theoretically, the extent of
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Equation A-2.7 0( ) 0 1. 5 σ = σ
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Cumulative Mass × 10 5 (g) dipping
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of PANI, and an increase in the con
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Resistance(ohm) 1.0E+12 1.0E+11 1.0
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esistance value. Samples containing
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The results of resistance for PS/PE
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Caruso, F., & Schuler, C. (2000). E
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