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Dispersion Stability, Microstructure and Phase Transition of Anisotropic Nanodiscs / by Ravi Kumar Pujala
Resource type: Ressourcentyp: Buch (Online)Buch (Online)Sprache: Englisch Reihen: Springer Theses, Recognizing Outstanding Ph.D. Research | SpringerLink BücherVerlag: Cham [u.a.] : Springer, 2014Beschreibung: Online-Ressource (XVI, 154 p. 95 illus., 26 illus. in color, online resource)ISBN:- 9783319045559
- 530.41
- 541.345 23
- QC176.8.A44
Inhalte:
Zusammenfassung: This thesis explores the dispersion stability, microstructure and phase transitions involved in the nanoclay system. It describes the recently discovered formation of colloidal gels via two routes: the first is through phase separation and second is by equilibrium gelation and includes the first reported experimental observation of a system with high aspect ratio nanodiscs. The phase behavior of anisotropic nanodiscs of different aspect ratio in their individual and mixed states in aqueous and hydrophobic media is investigated. Distinct phase separation, equilibrium fluid and equilibrium gel phases are observed in nanoclay dispersions with extensive aging. The work then explores solution behavior, gelation kinetics, aging dynamics and temperature-induced ordering in the individual and mixed states of these discotic colloids. Anisotropic ordering dynamics induced by a water-air interface, waiting time and temperature in these dispersions were studied in great detail along with aggregation behavior of nanoplatelets in hydrophobic environment of alcohol solutionsPPN: PPN: 1658627180Package identifier: Produktsigel: ZDB-2-PHA
Supervisor's Foreword; Abstract; Acknowledgments; Contents; 1 Introduction; Abstract ; 1.1 Soft Matter; 1.2 Colloids; 1.3 Colloids: Why are Physicists Concerned?; 1.4 Interactions in Colloidal System; 1.4.1 van der Waals Forces; 1.4.2 Double Layer Interactions (Repulsive Potential); 1.4.3 Interaction Energy Between Clay Particles; 1.5 Clays as Colloidal Systems; 1.6 Description of Nanoclays; 1.6.1 Laponite; 1.6.2 Montmorillonite; 1.7 Objective and Scope of Thesis; 1.8 Aging and Dynamic Arrest in Colloidal Systems; 1.9 Definition of Various Non-ergodic States; 1.9.1 Colloidal Gel
1.9.2 Colloidal Glass1.9.3 Comparison Between Gel and Glass; 1.10 Structure of the Thesis; References; 2 Materials and Characterization Techniques; Abstract ; 2.1 Materials Used; 2.1.1 Nanoclays; 2.1.2 Solvents; 2.2 Characterization Techniques; 2.2.1 Laser Light Scattering; 2.2.2 Rheology; 2.2.2.1 Modes of Operation; 2.2.3 Viscometry; 2.2.4 Tensiometry; 2.2.5 Electrophoresis; 2.2.6 Raman Spectroscopy; 2.2.7 Transmission Electron Microscopy; 2.2.8 X-Ray Diffraction; References; 3 Phase Diagram of Aging Laponite Dispersions; Abstract ; 3.1 Introduction; 3.2 Sample Preparation
3.3 Results and Discussion3.3.1 Hydration of Laponite; 3.3.2 Growth of Structures; 3.3.3 Viscoelastic Behaviour; 3.3.4 Dispersion Homogeneity at tw = 0; 3.3.5 Phase Diagram; 3.4 Conclusion; References; 4 Anisotropic Ordering in Nanoclay Dispersions Induced by Water-Air Interface; Abstract ; 4.1 Introduction; 4.2 Experimental Geometry; 4.3 Experimental Results; 4.3.1 Anisotropic Ordering at the Water-Air Interface; 4.3.2 Effect of Water-Hydrophobic Liquid Interface; 4.3.3 Effect of Temperature; 4.3.4 Relaxation Dynamics; 4.4 Discussion; 4.5 Conclusion; References
5 Phase Diagram of Aging Montmorillonite DispersionsAbstract ; 5.1 Introduction; 5.2 Sample Preparation; 5.3 Results and Discussion; 5.3.1 Time-Dependent Viscosity; 5.3.2 Visco-Elasticity; 5.3.3 Steady State Viscosity and Yield Stress; 5.3.4 Cole-Cole Plots; 5.3.5 Light Scattering Experiments; 5.3.6 Observation of Phase Separation and Equilibrium Gels and Phase Diagram; 5.3.7 Gelation Kinetics in Percolation Formalism; 5.4 Conclusions; References; 6 Sol State Behavior and Gelation Kinetics in Mixed Nanoclay Dispersions; Abstract ; 6.1 Introduction; 6.2 Sample Preparation
6.3 Result and Discussion6.3.1 Sol State Behavior; 6.3.2 Gel State Properties of Mixed Clay Dispersions; 6.3.3 Visco-Elastic Properties; 6.3.4 Gelation Kinetics in Percolation Formalism; 6.4 Conclusion; References; 7 Aging Dynamics in Mixed Nanoclay Dispersions; Abstract ; 7.1 Introduction; 7.2 Sample Preparation; 7.3 Results and Discussion; 7.3.1 Concentration Dependence; 7.3.2 Ergodicity Breaking Time; 7.3.3 Relaxation Dynamics; 7.3.4 Behavior of the System φ < φcutoff; 7.3.5 Growth of Anisotropy with Aging; 7.3.6 Cole-Cole Plot and Sample Heterogeneity; 7.4 Dilution Experiment
7.5 Conclusion
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