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in electrostatic repulsion and an enhancement of the amount of adsorbed polymer(Mattoso et al., 2005; Raposo & Oliveira Jr, 2002). Several studies(Cheung, et al., 1997; M. K. Ram, M. Salerno, M. Adami, P. Faraci, & C. Nicolini, 1999) did not succeed in assembling PANI/PSS films in the presence of PANI in its neutral state. Conductivity of PANI/PSS: some researchers have reported that with an increase of the number of adsorbed PANI/PSS bilayers, electrical conductivity of the multilayer increases until a saturation plateau is reached around the 13 th bilayer or the 25 th layer(Braga, et al., 2008; Paloheimo, Laakso, Isotalo, & Stubb, 1995). Further deposition of layers showed no more increase in the film’s electrical conductivity. 2.4.1.1.12 Characterization Techniques for LbL Deposited Layers Commonly used methods used to characterize the internal structure of the multilayer and film thickness could not be used in this research due to several limitations. Special techniques such as UV-Vis, ellipsometry(Schwarz, Eichhorn, Wischerhoff, & Laschewsky, 1999), quartz crystal microbalance (QCM)(Baba, Kaneko, & Advincula, 1999), streaming potential measurements (SPM)(Schwarz, et al., 1999), atomic force microscopy(AFM)(Caruso, Furlong, Ariga, Ichinose, & Kunitake, 1998), gravimetric measurement(Roy, et al., 2006), and x-ray and neutron reflectivity(Schmitt et al., 1993) have been utilized to measure thickness or mass deposited on the surface of each layer. Although the most commonly used method is UV-Vis, measurement of light absorbance is impossible due to the black color of the PANI solution. . As well, ellipsometry is one of the most appropriate techniques for showing the growth rate. As the technique works with the reflection of emitted light, it is limited for substrates with curved surfaces. 90
CHAPTER 3 - ORGANIZATION OF THE ARTICLES To achieve the main objective of this work, an elegant technique to reduce the continuity and/or electrical percolation threshold of a conductive polymer is developed by increasing the number of continuous structures in polymer blends. Polyaniline and four other commercial polymers with specific surface tensions, polarity and interfacial tensions are precisely selected. The interfacial tensions between various components show a range from 1 mN/m for PVDF/PMMA to 26.9 mN/m for PANI/HDPE. Morphological sample characterization is performed by both SEM and FIB-AFM techniques. The polymer blends are prepared in a melt-blending process in an internal mixer at 50 rpm for 8 min at 200°C. Selective solvent extraction of phases either assists in better detection of phases in order to collect qualitative data, or is employed to produce porous samples. Combination of FIB treatment and AFM technique allows us to clearly distinguish the phases based on the topographical contrast formed by the difference in FIB etching rate of materials. In order to study the effect of viscosity ratio on the ternary blends, both low molecular weight and high molecular weight poly(methyl methacrylate) are selected. Fully interconnected porous materials are used as substrates for alternate deposition of PSS and PANI. In the first step, three components, namely high density polyethylene (HDPE), polystyrene (PS), and poly(methyl methacrylate) (PMMA), are carefully chosen to satisfy the thermodynamic conditions. The positive spreading coefficient of PS over PMMA predicts that the PS phase situates at the interface of the HDPE and PMMA phases, and a complete wetting case occurs. Experimental results confirms the prediction of the morphology by the spreading theory as the identification of the phases can be clearly seen by the topographical heights induced by FIB etching and subsequently quantified by AFM analysis in the topographical mode. Addition of fourth phase (PVDF) to the ternary blend with complete wetting of HDPE/PS/PMMA, provided that the entire set of thermodynamic spreading equations is satisfied, results in hierarchically ordered phases of HDPE|PS|PMMA|PVDF. The Harkins spreading theory predicts a hierarchically ordered structure of HDPE|PS|PMMA|PVDF|PANI by addition of PANI to a quaternary HDPE|PS|PMMA|PVDF blend. Experimental results show a very good consistency between these predictions and qualitative results. 91
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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
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One of the applications for porous
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On the other hand, a novel tri-cont
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2.1 Polymer Blends CHAPTER 2 - LITE
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Based on Sterling’s approximation
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Antonoff’s rule (Equation 2-13) i
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2.1.2.1 Binary Polymer Blends 2.1.2
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Some other studies(Everaert, Aerts,
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where the parameter z is dependent
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“compatibilization” was suggest
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a) λ BC A and B are matrices, b) C
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Reignier & Favis, 2000, 2003a; Reig
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measure the interfacial tension of
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a) b) Figure 2-6. Dependence of the
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Omonov et al. found double percolat
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2.1.2.2.3 Effect of Composition on
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a) b) C B A c) Figure 2-12. SEM pho
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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 and 102: Figure 2-24. Plot of the total numb
Page 103 and 104: chain provides the conductive path
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: increasing the pH value due to a de
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
Page 153 and 154: 4.3.6 Conductivity Measurements DC
Page 155 and 156: experimentally in this research gro
Page 157 and 158: a) b) c) d) Figure 4-4. Schematic i
Page 159 and 160: microstructure of the quaternary bl
Page 161 and 162: a) b) c) d) Figure 4-6. SEM microgr
Page 163 and 164: a) b) PVDF PS PMMA c) d) e) HDPE PS
Page 165 and 166: Uniform layers of PS and PMMA situa
Page 167 and 168: the concentration of HDPE is increa
Page 169 and 170: a) b) c) e) Figure 4-11. SEM microg
Page 171 and 172: melt-processable and contains 25 wt
Page 173 and 174: One question that should be address
Page 175 and 176: Conductivity(S/cm) Ternary Blend 1,
Page 177 and 178: phase(PMMA), the concentration of P
Page 179 and 180: (6) Virgilio, N.; Desjardins, P.; L
Page 181 and 182: ONION MORPHOLOGY HDPE PVDF PS Contr
Page 183 and 184: work described above has focused on
Page 185 and 186: 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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