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annealing to increase the phase sizes. Solvent extraction was used to extract various components and generate porosity in the substrate. Selective solvent extraction also allows for the determination of the percent continuity of the different components in the blend system. The characterization, aimed at gaining insight on the morphology of polymer blends, is carried out via two techniques. Scanning electron microscopy (SEM) and focused ion beam (FIB)-atomic force microscopy (AFM) provide information about the morphology of the samples and the thickness of the constructed multilayer. After cryogenically microtoming the sample and coating it with a gold-palladium layer, the sample is etched by using FIB, demonstrating a topographic contrast between phases. Such topography allows the phases to be distinguished and this is quantified by AFM. Conductivity measurements were performed through the vertical thickness of the substrates with an electrometer. In the first part of this study, a solid, 3D, low percolation threshold conductive device prepared through the control of multiple encapsulation effects in a five-component polymer blend system through melt processing is fabricated. This multi-percolated structure approach is thermodynamically controlled and is described by the Harkins spreading theory, demonstrating spreading of all phases, including the conductive polymer phase, throughout the blend. A quinary blend of PANI and four other components: polyethylene (PE), polystyrene (PS), poly(methyl methacrylate) PMMA, and poly(vinylidene fluoride) (PVDF) are precisely selected to show multi-percolated structure with a percolation threshold less than 5%. In order to locate PANI at the core of this quadruple-percolated structure, all the interfacial tensions between phases must satisfy the Harkins equation and show various complete wetting morphologies with the desirable hierarchical ordering of the phases (HDPE|PS|PMMA|PVDF|PANI). The detailed morphology and continuity diagrams of binary, ternary, quaternary, and finally, quinary systems for PE, PS, PMMA, PVDF, and PANI, are progressively studied in order to systematically demonstrate the concentration regimes resulting in the formation of these novel multiple-encapsulated morphological structures. It is shown that through the control of the composition of the inner and outer layers in the onion-type dispersed phase structures, the morphology can be transformed to a hierarchical self-assembled, multi-percolated structure. This approach helps control the morphology of continuous phases, leading to a geometrical restriction for the phases and sharply reduces the percolation threshold of phases. In this fashion, the conductivity of the quinary blend x
system can be increased from 10 -15 S cm -1 (pure PE) to 10 -5 S cm -1 at 5% PANI and up to 10 -3 S cm -1 for 10% PANI. These are the highest conductivity values ever reported for these PANI concentrations in melt processed systems. In the second part of the study, a novel 3D porous polymeric conducting device is derived from multi-percolated polymer blend systems. The work has focused on the preparation of ultra-low surface area porous substrates followed by the deposition of polyanilene conductive polymer (PANI) on the internal porous surface using a layer-by-layer self-assembly technique. The approach reported here allows for the percolation threshold concentration of polyaniline conductive polymer (PANI) to be reduced to values as low as 0.19%. Furthermore, depending on the amount of PANI deposited, the conductivity of the porous substrate can be controlled from 10 -15 S cm -1 to 10 -3 S cm -1 . Ternary and quaternary multi-percolated systems comprised of high- density polyethylene(HDPE), polystyrene(PS), poly(methyl methacrylate)(PMMA) and poly(vinylidene fluoride)(PVDF) are prepared by melt mixing and subsequently annealed in order to obtain large interconnected phases. Selective extraction of PS, PMMA and PVDF result in a fully interconnected porous HDPE substrate of ultra low surface area and highly uniform sized channels. This provides an ideal substrate for subsequent polyaniline(PANI) addition. Using a layer-by-layer(LbL) approach, alternating poly(styrene sulfonate)(PSS)/PANI layers are deposited on the internal surface of the 3-dimensional porous polymer substrate. The PANI and sodium poly(styrene sulfonate)(NaPSS) both adopt an inter-diffused network conformation on the surface. The sequential deposition of PSS and PANI has been studied in detail and the mass deposition profile demonstrates oscillatory behavior following a zigzag-type pattern. The presence of salt in the deposition solution results in a more uniform deposition and more thickly deposited PSS/PANI layers. The conductivity of these samples was measured and the conductivity can be controlled from 10 -15 S cm -1 to 10 -5 S cm -1 depending on the number of deposited layers. Applying a load to the substrate can be used as an additional control parameter. Higher loads result in higher conductivity values with values as high as 10 -3 S cm -1 obtained. The work described above has focused on very low surface area porous substrates in order to determine the lowest possible percolation threshold values of polyaniline, but high surface area substrates can also be readily prepared using this approach. xi
Page 1 and 2: © Sepehr Ravati, 2010. UNIVERSITÉ
Page 3 and 4: DEDICATED To my parents iii
Page 5 and 6: RÉSUMÉ Cette thèse présente, po
Page 7 and 8: devenir une structure hiérarchique
Page 9: ABSTRACT This thesis presents, for
Page 13 and 14: CONDENSÉ EN FRANÇAIS Dans ce trav
Page 15 and 16: deuxième coquille de PS. Les phase
Page 17 and 18: structures à percolation multiple
Page 19 and 20: autre sous-type de morphologie dans
Page 21 and 22: TABLE OF CONTENTS DEDICATION.......
Page 23 and 24: xxiii 2.4.1.1.1 Charged Polymer Ads
Page 25 and 26: 5.3.4 Annealing Test ..............
Page 27 and 28: xxvii REFERENCES ..................
Page 29 and 30: LIST OF FIGURES xxix Figure 1-1. a)
Page 31 and 32: Figure 2-12. SEM photomicrograph of
Page 33 and 34: Figure 2-34. Schematic view of diff
Page 35 and 36: Figure 4-8. SEM micrographs of vari
Page 37 and 38: Figure 5-6. a),b) Scanning electron
Page 39 and 40: and c) triangular concentration dia
Page 41 and 42: n number of moles p concentration o
Page 43 and 44: AFM atomic force microscopy LIST OF
Page 45 and 46: PS-co-PMMA copolymer of PS and PMMA
Page 47 and 48: 1.1 Introduction CHAPTER 1 - INTROD
Page 49 and 50: 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
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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,
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Posthuma de Boer, 1999) (Kumin & Ch
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lattice, such as square lattice, wi
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magnetization, which is a function
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Polymers have long been thought of
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epoxy as a function of nanotube wei
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Figure 2-19. Approaching the percol
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Figure 2-21. Transmission electron
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Figure 2-22: Dependence of PE conti
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Figure 2-24. Plot of the total numb
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chain provides the conductive path
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2.3.1.2.1 Polyaniline One of the mo
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CoPA/LLDPE/PANI blend and a poor-qu
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Narkis and co-workers extended and
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Figure 2-31: Conductivity of PVDF/P
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organic thin films, a novel and str
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on the topic have been reported in
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succeeded in creating thin films wi
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Addition of salt to the solution of
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different from that of linear homop
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Figure 2-39. Macromolecule with a)
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polyanion such as hyaluronan (HA)(P
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2.4.1.1.7 Effect of Salt on Multila
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2.4.1.1.8 Overcompensation of the M
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important factors determining the g
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As shown in Figure 2-44, swelling a
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increasing the pH value due to a de
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CHAPTER 3 - ORGANIZATION OF THE ART
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discussed above, HDPE, PS, PMMA, an
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CHAPTER 4 - LOW PERCOLATION THRESHO
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or model which predicts where the p
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concentration threshold for the ons
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chemical and weathering resistance,
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Table 4-1. Material Characteristics
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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.,
Page 263 and 264:
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
Page 271 and 272:
Niziol, J., & Laska, J. (1999). Con
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Reghu, M., Yoon, C. O., Yang, C. Y.
Page 275 and 276:
Shirakawa, H., Louis, E. L., MacDia
Page 277 and 278:
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
Page 301 and 302:
Resistance(ohm) 1.0E+12 1.0E+11 1.0
Page 303 and 304:
esistance value. Samples containing
Page 305 and 306:
The results of resistance for PS/PE
Page 307 and 308:
Caruso, F., & Schuler, C. (2000). E
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