Emulsion templated assembly of composite particles

Composite particles are attractive multi-constituent systems. Depending on their structure and chemical composition, they can be used for applications such as bio-separation, hetero-catalysis, theragnostic, and antimicrobial application. However, their preparation often presents significant practical, economic, and environmental limitations. This work presents a novel method for "building up" multifunctional inorganic composite particles at room temperature via salt-driven assembly of readily available nanoparticles in emulsion droplets. With the emulsion acting as a geometrical template, the structure and size of the final system can be controlled. Using nanoparticles as building blocks, enables facile tuning of the final system to produce materials with multiple properties. Due to those two features, complex structures can be produced without the use of toxic chemicals, high temperatures, or bespoke lab equipment. The first chapters of this work focus on the preparation of composite microparticles in reverse emulsion templates (W/O) and the use of those systems for biological and environmental applications. Magnetic silica particles (Fe3O4/SiO2) were produced for use as a low-cost and easy to implement biological separation technique, aiming to offer a sustainable alternative to commercial DNA purification kits for resource constrained labs. Magnetic photocatalysts (TiO2/Fe3O4/SiO2) were prepared for use as an easily recoverable system for adsorption and light-induced degradation of synthetic dyes (e.g. Rhodamine B and Methylene blue) from water. Antibacterial magnetic particles (ZnO/CuO/Fe3O4/SiO2) were assembled and investigated for use as an inexpensive approach for disinfecting surfaces. The final chapters explore the optimization of this approach for producing more diverse systems such as nanocomposites and composite microcapsules. Nanocomposites were successfully produced in a reverse emulsion template by using a high energy emulsification method (i.e. ultrasonic homogenization). Multicore silica microcapsules were prepared via assembly of commercial nanoparticles within a double emulsion template (O/W/O). Using this approach nanoparticle-assembled capsules with adjustable diameter, internal structure and functionalities were prepared, offering a promising approach for producing tuneable multifunctional systems for oil encapsulation. We believe the work presented in this thesis establishes a significant advance in the preparation of composite materials, offering a green, versatile, and easy to implement procedure for producing novel colloidal materials for biological and environmental applications using cheap, commercially available nanoparticles as building blocks.