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Following this, the desorption or detachment of some layers is expected in an oppositely charged PANI solution when mobile chains diffuse out. As soon as they reach the surface, an additional reaction occurs between them and the oppositely charged chains available in the solution and an extra layer is formed. In this fashion, a diffuse network structure throughout the deposited thickness is observed in contrast to the formation of discrete polyelectrolyte layers in classic layer-by-layer deposition where strong polyelectrolytes are used. Based on the above discussion, a schematic representation of film growth has been made to show the progressive formation of multilayers (Figure 5-8). This schematic contrasts with the classic formation of well-separated hierarchical alternating multilayers observed in most work using the LbL approach. In the current work, the oscillating deposition indicates that PSS and PANI polyelectrolytes diffuse into the previously deposited layers. Like chains make contact with other like chains and consequently, an inter-diffused network of PANI and PSS is generated. In a following section, it will be shown that an increase in the conductivity is observed as a function of the number of PSS and PANI layers and it further confirms the formation of a continuous network of PANI interdiffused with PSS. The degree of interconnection of this network becomes more pronounced as the number of deposited layers increases. As well, an increase in the number of deposited layers results in a rougher surface, leading to a further diffusion of free chains. Figure 5-8. Schematic of exponential growth of PSS/PANI multilayer thickness on the internal surface of the substrate. 5.4.6 The Effect of Salt on the Mass Deposition Growth of PSS/PANI Salt is generally added in procedures involving LbL deposition. In the absence of salt, charged PSS and PANI in the solution adopt a more expanded rigid, rod-like configuration due to coulomb repulsion(Ha & Thirumalai, 1995). The role of salt is to gradually screen the monomermonomer repulsive interactions between PSS charges with counter-ions and also bring them 162
close together. It is interesting to note in Figure 5-7 that the addition of salt significantly increases the oscillation behavior of the mass growth dynamics. This oscillation behavior can be explained as follows: the number of PSS molecules that diffuse throughout the multilayer and the total concentration of these free chains depend on the electrostatic interaction forces that arise from total overcompensation. Two important parameters influencing the extent of overcompensation are the concentration of added salt and the number of layers. Thus, extra overcompensation is caused by the presence of NaCl in the PSS solution(Klitzing & Moehwald, 1995). As well, the displacement of hydrated small salt counterions and charged polymer segments result in highly swollen polymers as attached water molecules are brought in(Dubas & Schlenoff, 2001c). Jaber et al. (Jaber & Schlenoff, 2007) showed that salt counter-ions can thermodynamically control up to 40% of the mass deposition of the multilayer construction due to this additional water content. Swelling and overcompensation occur simultaneously during the construction of the multilayer in the presence of salt(Dubas & Schlenoff, 2001b), which is involved in the dramatic mass increase of the multilayer. In a subsequent dipping step in the PANI solution, the electrostatic interaction between the diffused hydrated PSS with PANI chains inside the solution play a major role in the diffusion of free PSS chains out of the multilayer. At this step, in the presence of salt, a significant decrease in mass deposition is detected which is proportional to the mass increase in the previous step(PSS adsorption) as compared to a slight decrease in mass in solutions without salt. Consequently, the amount of thickness growth highly depends on the amount of salt that affects the electrostatic interactions and increases the driving force for diffusion in and out of the multilayer. Mass deposition growth for the PSS/PANI system in cases where salt is both present and absent, is not linear since a progressive increase of each polyelectrolyte after its deposition is detected (Figure 5-9). As the number of layers increases, the extent of free chains going inward and outward increases exponentially due to increase the amount of overcompensation (Figure 5-9). In other words, at each adsorption step, more PSS is adsorbed than that removed in the previous step, leading to nonlinear layer growth. The rates of increase and decrease of PSS and PANI at 163
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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,
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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
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
Page 187 and 188: four-point probe increases continuo
Page 189 and 190: in the rheology tests were compress
Page 191 and 192: 5.3.6 Layer-by-Layer Deposition The
Page 193 and 194: prepare a polymer blend structure w
Page 195 and 196: a) b) c) Figure 5-3. Scanning elect
Page 197 and 198: spontaneously self-assembled. After
Page 199 and 200: a) b) c) d) e) f) g) h) Figure 5-5.
Page 201 and 202: Since the ultra-low surface area va
Page 203 and 204: c) a) b) Figure 5-6. a),b) Scanning
Page 205 and 206: salt to a PSS polyelectrolyte solut
Page 207: A relationship between macropore si
Page 211 and 212: Figure 5-9. Mass increase (%) indic
Page 213 and 214: In this work the conductance of the
Page 215 and 216: deposited PANI layers increases unt
Page 217 and 218: (52) Guo, H. F.; Packirisamy, S.; G
Page 219 and 220: 6.2 Introduction It is well-known t
Page 221 and 222: modified version of Harkins theory(
Page 223 and 224: 6.3 Experimental 6.3.1 Materials Co
Page 225 and 226: Complex voscosity (Pa.s) 1,0E+04 1,
Page 227 and 228: 6.3.5.2 Focused Ion Beam (FIB) and
Page 229 and 230: a) c) b) d) e) f) PMMA PMMA HDPE HD
Page 231 and 232: y Harkins theory, PS will always si
Page 233 and 234: a) b) c) d) e) f) PS Figure 6-6. a)
Page 235 and 236: a) b) HDPE : black PS : grey PMMA :
Page 237 and 238: 6.4.6 Continuity, Co-continuity, an
Page 239 and 240: c) V III II I VII I IV VI Figure 6-
Page 241 and 242: Continuity Scheme (a) Figure 6-10.
Page 243 and 244: Addition of a low concentration of
Page 245 and 246: Addition of small amounts of HDPE t
Page 247 and 248: icontinuous network with the HDPE.
Page 249 and 250: Three examples are shown in Figure
Page 251 and 252: (9) Mekhilef, N.; Verhoogt, H. Poly
Page 253 and 254: structures are formed due to the co
Page 255 and 256: CONCLUSION AND RECOMMENDATIONS In t
Page 257 and 258: 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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