| dc.description.abstract | The focus of this Ph.D. thesis is to study functionalization and associated self-assembly of clay mineral in suspensions. Clay minerals are two-dimensional materials. They are among the most abundant, highly sustainable, and environmentally friendly natural materials. Consequently, they are used in a wide range of applications. Smectites are a type of clay minerals known as swelling or expandable clays, which can expand by the adsorption of guest molecules, such as water, carbon dioxide, drugs, or others. The smectite nanolayers exhibit a net negative charge, and exchangeable cations balance this charge in between the layers. In present thesis, the smectite used is e synthetic Fluorohectorite.
The present thesis reports in-situ and ex-situ investigations of the self-assembly and self-organization behaviors of unmodified and modified clay nanolayers under different circumstances. While pursuing these goals, nanolayers were achieved by an ordered-interstratification procedure and subsequent exfoliation in water yielding double-nanolayer suspensions.
It is demonstrated that single and double layers of unmodified clays experience a dynamic equilibrium at the air-liquid interface. Also, this work demonstrates that Fluorohectorite monolayer suspensions can exhibit structural colors for certain concentrations and that the color brightness is greatly increased when suspensions of double nanolayers are used instead of single clay nanolayers. This system readily and rapidly yields very bright and additionally non-iridescent colors. These structural colors can easily be tuned by nanolayer concentration or ionic strength of suspending water.
Finally, this work studies the self-assembly of functionalized magnetic nanoparticles onto double-nanolayer clay surfaces. The functionalized double-layers can be cleaved, resulting in two-dimensional magnetic Janus particles. These hybrid structures show good shelf stability and can easily be orientated by moderate magnetic fields when suspended in water. In future works, the present findings should be translated to high aspect ratio natural clay minerals such as vermiculite. This would be a very important avenue for obtaining industrial upscaling of the results presented here. | en_US |
