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APPENDIX III A- 3 Mechanism of Aggregation of Weak Polyelectrolytes Weak polyelectrolytes have some advantages compared to strong ones, such as the possibility of tuning their properties by simple pH adjustment. In strong polyelectrolytes, the charges remain over the entire pH range. On the contrary, for weak polyelectrolytes, the degree of ionization depends on the pH of the solution. In this thesis, the pH of polyaniline solution is set constant at 2.5 for all samples in order to have the equal fraction of charges for layers. Moreover, the weak PANI shows a “poor” nature in aqueous solutions(Cheung, et al., 1997). Such poor solvent quality indicates that the polyaniline solution can only be used for about 1-2 weeks before important aggregation of the polyaniline chains happens(Cheung, et al., 1997). In this case, a large amount of polymer chains is adsorbed per layer and multilayer deposition cannot be controlled. The aggregation of polyelectrolytes in a solution throughout layer-by-layer experiments was studied over time for sample B in Chapter 5 in two steps (Figure A-3.1). In the first continuous process, 22 layers were deposited onto the 3D substrate. After the deposition of the 22 nd layer, all the solutions were left for three weeks to allow the chains to make aggregates. The second LbL process was continued by the same solutions and substrates, whereas layers 23 to 37 were deposited on the previously prepared multilayer. In this protocol, two different growth rates of deposition of NaPSS for either step were obtained. The deposition process with fresh solutions exhibited a growth rate of 3.04, while a higher growth rate value of 6.27 was obtained for the remaining sample. Such a high growth rate demonstrates the aggregation deposition of chains in the second step instead of the deposition of a few chains in the first step. Correspondingly, a solution containing fresh PANI shows a rate of desorption of 2.28, compared to the solution used in the second step with a rate of 5.22. The aggregation of PANI resulting from the poor nature of the PANI solution is proposed as the main reason for the increase of the growth and desorption rates. Therefore, in the second step, a large number of aggregated PANI chains was deposited, yielding a significant increase in electrostatic force. In the subsequent 250
Cumulative Mass × 10 5 (g) dipping PSS process, a proportional extent of PSS was deposited to compensate for this electrostatic force. 180 160 140 120 100 80 60 40 20 0 PANI PSS S = 3.04 S = 2.28 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Number of Layers S = 6.27 S = 5.22 Figure A-3.1. Cumulative deposited mass in LbL process on sample(B) for both PANI and NaPSS polyelectrolytes as a function of number of layers. 251
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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
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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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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
Page 259 and 260: Caruso, F. (2003). Hollow Inorganic
Page 261 and 262: Domenech, S. C., Bortoluzzi, J. H.,
Page 263 and 264: Geuskens, G., Gielens, J. L., Geshe
Page 265 and 266: Hou, S., Harrell, C. C., Trofin, L.
Page 267 and 268: Krass, H., Papastavrou, G., & Kurth
Page 269 and 270: Macdiarmid, A. G., Jin-Chih, C., Ha
Page 271 and 272: Niziol, J., & Laska, J. (1999). Con
Page 273 and 274: 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
Page 279 and 280: Yasuda, K., Armstrong, R., & Cohen,
Page 281 and 282: literature has examined factors inf
Page 283 and 284: (Reignier & Favis, 2000, 2003a; Rei
Page 285 and 286: Table A-1.2. Interfacial tensions a
Page 287 and 288: acquisition of images with a very h
Page 289 and 290: Table A-1.3. Continuity of the PMMA
Page 291 and 292: (17) Reignier, J.; Favis, B. D., Ma
Page 293 and 294: PANI. Theoretically, the extent of
Page 295: Equation A-2.7 0( ) 0 1. 5 σ = σ
Page 299 and 300: 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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