A Bio-Inspired Approach to Functional Composite Crystals

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Nanocomposites are an exciting class of materials, where the ability to engineer compositions, structures and properties at the nanoscale and mesoscale promises multi-functionality and novel properties. This project will develop a new strategy for fabricating nanocomposites with unique structures - single crystals containing occlusions ranging from small molecules to nanoparticles (NPs). The inspiration for our approach comes from the remarkable structures and properties of biominerals, and in particular their composite structures. Even single crystal biominerals are inorganic/ organic composites in which proteins are embedded within the crystal lattice. Thus, although crystallisation is traditionally used for purifying materials, nature shows us that additives can be efficiently occluded under appropriate conditions. This PhD project comprises three sub-projects(1) We will profit from crystals with composite inorganic/ organic structures to generate porous crystals. Calcium carbonate crystals will be precipitated in the presence of a range of organic molecules, leading to their occlusion within the crystal structure. The crystals will then be annealed to generate porous crystals. A wide range of oraic additives and heating regimes will be explored to give optimal results. This offers a novel and simple synthetic strategy for tailoring the densities and refractive indices of minerals.(2) Our strategy will also be used to create minerals that exhibit structural colour. Sub-micron particles with a range of sizes will be occluded in single crystal and polycrystalline particles with the goal of tuning the colour of these particles. The influence of the particle size, the density andlocation of the particles within the crystals will be explored as a means of controlling the colours of the crystals.(3) Calcium carbonate is produced on an industrial scale using a synthesis based on calcium hydroxide. We will explore how this method of producing "precipitated calcium carbonate" can be applied to the synthesis of composite crystals, enabling our reaction strategies to be scaled-up and employed in industry.