Bio-inspired Hierarchies of Functional Materials

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We describe project modules that take a page from nature. Our plan is to cultivate species of diatoms and coccolithophores and to use them to make new kinds of materials and devices. Diatoms are single cell aquatic organisms that are responsible for about 20% of the Earth's oxygen supply. Interestingly, they create their own glass (silica) shells to contain and protect their bio-components. The glass shells are called frustules and they exhibit ornate patterns that are of interest to nanoscience. Coccolithophores are also single cell marine organisms, but that create an elaborate shell from calcium carbonate. It is the ornate patterns and the materials from which the shells are made that inspire us. In one module of research we plane to dissolve the silica shell of different species of diatom to learn how the underlying silica morphology determines the kinetics of the process. The real reason for studying this reaction is to find new pathways to organosilicon compounds that currently are made by carbothermal reduction of silica to silicon, and its subsequent conversion to feedstock organosilanes. We plan to use the depolymerization products to reassemble the organosilicon into mesoporous solids. These are highly porous silica materials of interest to catalysis. In another module, we will convert the shells of diatoms and coccolithophores to functional organic polymers and glasses by "molding" polymers and glasses around the shells. Subsequently, we dissolve away the shells to give "plastic" or glassy replicas. But these replicas might be used as oxygen sensors, for example. In a third module, we convert the shells to carbon and use the inverse replicas to make new kinds of 3-dimensional objects that may or may not be silica-based. In the fourth Module we examine how light interacts with the 3D structure of the shell. This is important for sensors, lasers and other optical responses, since light can become trapped in the ultrastructure, or rejected altogether.