Colloidal Interactions and Stability in Processing, Formation and Properties of Inorganic-Organic Nanocomposites

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Colloidal Interactions and Stability in Processing, Formation and Properties of Inorganic-Organic Nanocomposites COLLOIDAL INTERACTIONS AND STABILITY IN PROCESSING, FORMATION AND PROPERTIES OF INORGANIC-ORGANIC NANOCOMPOSITES by SAEED M. ALHASSAN Submitted in partial fulfillment of the requirements For the degree of Doctor of Philosophy Department of Chemical Engineering CASE WESTERN RESERVE UNIVERSITY May 2011 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of ______________________________________________________Saeed M. Alhassan candidate for the ________________________________degreeDoctor of Philosophy *. (signed)_______________________________________________Dr. Syed Qutubuddin (chair of the committee) Dr. J. Adin Mann Jr. ________________________________________________ ________________________________________________Dr. R. Mohan Sankaran ________________________________________________Dr. David Schiraldi ________________________________________________ ________________________________________________ (date) _______________________March 10th, 2011 *We also certify that written approval has been obtained for any proprietary material contained therein. Copyright © by Saeed M. Alhassan All Rights Reserved To my mother, my family and my wife… Table of Contents Table of Contents…………………………………….....…..…………..………….…….i List of Tables……………………………………………………………………………..iv List of Figures………………………………………………………………………........v Acknowledgments………………………………………………………………………xiii Abstract………………………………………………………………………...………. xiv 1. Introduction …………………………………………………………………………..1 1.1. Thesis scope and objectives…………………………………………………1 1.2. Colloidal interactions and stability………………………………………….4 1.3. Turbulence…………………………………………………………………..14 1.4. References…………………………………………………………………..18 2. Influence of electrolyte and polymer loadings on mechanical properties of clay aerogel……………………………………………………………………………….......20 2.1. Introduction…………………………………………………………………20 2.2. Experimental section………………………………………………………..27 2.2.1. Materials.………………………………………………………….27 2.2.2. Preparation of standard NaCl solutions……………………….......27 2.2.3. Aerogel preparation……………………………………………….27 2.2.3.1. MMT aerogels…………………………………………..27 2.2.3.2. PVOH/MMT aerogels…………………………………..28 2.2.4. Characterization…………………………………………………..30 2.3. Results and discussion…………………………………………………........31 2.3.1. Aerogel density and morphology……………………………........31 2.3.2. Mechanical Properties…………………………………………….39 2.4. Conclusions…………………………………………………………………53 2.5. References…………………………………………………………………..54 3. Graphene production via turbulent mixing in water at ambient conditions…………..57 3.1. Introduction…………………………………………………………………57 3.2. Properties of graphene and graphite……………………………………….58 3.3. Graphene production methods……………………………………………..71 3.4. Laponite…………………………………………………………………….76 3.5. Experimental………………………………………………………………..78 3.5.1. Materials…………………………………………………….........78 3.5.2. Equipments………………………………………………….........79 3.5.3. Exfoliation procedures……………………………………………80 3.6. Results and Discussion……………………………………………………...80 3.6.1. Exfoliation process………………………………………………..80 3.6.2. Laponite Wigner glasses…………………………………………..83 3.6.3. Laponite films and X-ray diffraction……………………………..86 3.6.4. Transmission electron microscopy (TEM)………………………..93 3.6.5. Raman spectroscopy………………………………………………98 3.7. Conclusions………………………………………………………………..109 3.8. References………………………………………………………………….110 4. Polybenzoxazine nanocomposites…………………………………………………...116 4.1. Introduction………………………………………………………………..116 4.2. Experimental section……………………………………………………….120 4.2.1. Materials…………………………………………………………120 4.2.2. Synthesis of (B-mda)…………………………………………….120 4.2.3. Synthesis of Graphene Oxide……………………………………120 4.2.4. Preparation of aerogels…………………………………………..121 4.2.5. Preparation of nanocomposites…………………………………..121 4.2.6. Characterization……………………………………………….....122 ii 4.3. Results and discussion……………………………………………………..123 4.3.1. Aerogels produced from B-mda…………………………………123 4.3.2. Graphene oxide…………………………………………………..137 4.3.3. Nanocomposites fabricated from B-mda and GO……………….143 4.4. Conclusions………………………………………………………………...155 4.5. References………………………………………………………………….155 5. Conclusions and future directions……………………………………………………159 5.1. Clay aerogels……………………………………………………………….159 5.2. Turbulent exfoliation………………………………………………………160 5.3. Polybenzoxazine…………………………………………………………...161 6. Bibliography…………………………………………………………………………163 iii List of Tables Table 2.2.3.2.1 List of materials used for each aerogel sample…………………………29 Table 2.3.1.1. Density (g/cc) of aerogels obtained with fixed clay loading (see text)…..32 Table 4.3.1.1. Key physical properties for solvents used in B-mda aerogels and nanocomposites preparation…………………………………….....................................126 Table 4.3.1.2. Key properties for benzoxazine aerogels as function of initial solid content…………………………………………………………………………………..132 Table 4.3.3.1. Summary of Tg for PB-mda with different GO content……..................149 Table 4.3.3.2. Summary of key thermal properties from TGA measurements………...152 iv List of Figures Figure 1.2.1. Schematic showing the difference in sediment formed from stable and unstable clay suspensions (Van Olphen 1991)....................................................................5 Figure 1.2.2. Crystal structure of clay mineral belonging to the smectite family (2:1) showing the layered structure with the exchangeable cations residing in the interlayer gallery (Murray 2007)……………………..........................................................................7 Figure 1.2.3. Total interaction energy between two particles as function of separation distance according to DLVO theory (Israelachvili 1991). Insets: top right shows the primary minimum, secondary minimum and energy barrier; bottom right shows the total interaction potential as function of electrolyte loading (low electrolyte concentration (a) to high electrolyte concentration (e)).................................................................................10 Figure 1.2.4. Schematic showing polymer random coil confirmation in solution (a); and train, loop and tail confirmation when adsorbed to a surface (b) (Lyklema 2000)...........11 Figure 1.2.5. Effect of polymer adsorption on clay stability: A) small amount of polymer adsorbed onto clay surface followed by electrolyte addition leads to “sensitization”, B) addition of more amount of polymer leads to adsorption and bridging flocculation, C) addition of excessive amount of polymer leads to steric stabilization (Theng 1979)…...12 Figure 1.3.1. Sketch from Leonardo Da Vinci’s notebook showing water flow with eddies of different scales (Davidson 2004)………………………………………………14 Figure 1.3.2. Schematic showing the transition from laminar flow to turbulent flow in a boundary layer geometry (Davidson 2004)………………………...................................15 Figure 1.3.3. Schematic showing the energy cascade concept in isotropic and homogenous turbulence. The similarity in the energy cascade to the water swirling flow in Figure 1.3.1 is striking (Davidson 2004)……………………………………………..17 Figure 2.1.1. Crystal structure of smectite family showing the layered structure with the exchangable cations residing in the interlayer gallery (Murray 2007)………………......22 Figure 2.1.2. Edge structure of montmorillonite and the effect of proton concentration on the type of charge; positive at low and neutral pH and negative at high pH (Bergaya, Theng et al. 2006).............................................................................................................24 Figure 2.1.3. Bingham yield stress as function of electrolyte for three different clay- water dispersions, illite, montmorillonite and kaolinite (Van Olphen 1991)……………24 v Figure 2.1.4. Schematic showing the effect of salt (electrolyte) on the extent of electrical double layer of clay layers. The electrical field is shown as hyperbolic field, which is an oversimplified picture of the actual field. Moreover, the electrical field due to the edge of clay layer does not necessarily extend or add to the electrical field of the face (Bergaya, Theng et al. 2006)………………………………………………………………………..25 Figure 2.3.1.1. Optical images showing clay gels (A) and clay aerogels (B)…………...32 Figure 2.3.1.2. Theoretical and measured relative densities for CxPy aerogels as a function of PVOH volume fraction at the lowest and highest electrolyte loadings……...34 Figure 2.3.1.3. SEM image of pristine clay aerogel showing the ordered layer structure..............................................................................................................................35 Figure 2.3.1.4.SEM micrographs for C5P2E01 (A) and C5P2E0 (B). Morphology of C5P2E01 shows different morphology compared to C5P2E0…………………………...36 Figure 1.3.1.5. SEM micrographs for C5P5E0 at two different magnifications………...37 Figure 2.3.1.6. Images showing the structure of three cross section of Columbian pine (Gibson and Ashby 1997)………………………………………………………………..38 Figure 2.3.1.7. SEM micrographs for C5P4E0 at two different magnifications………...39 Figure 2.3.2.1. Stress-Strain curve for pristine clay aerogel; the brittle behavior of the aerogel is shown as fluctuating change in stress-strain curves…………………………..40 Figure 2.3.2.2. Typical stress-strain curves for C5PxE01 aerogels. The three regimes are linear elasticity (0-2% strain), plateau of plastic yielding (5% strain to onset of densification) and densification. Magnified linear elastic region is depicted in the inset graph. By increasing PVOH mass fraction, the elastic, plateau and densification regions shift toward lower
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