| Our ability to control the composition, size, and shape of metal oxide-based nanostructures has progressed over the past decade to a level that we can now control the functional properties of these with a high degree of accuracy. In this proposal we want to make a leap forward in inorganic materials development, and design and assemble such objects to form larger, hierarchical structures. The aim is to develop strategies that combine material synthesis and (self-)assembly of nanosized ?building blocks? (spheres, cubes, wires, rods, core-shell structures, etc.), into mesoscale architectures with 3D spatial control over the location of elements of the assembly. In such hierarchical structures, the traditional molecular length scale is far extended, and collective effects determine the property of the assembly. It is our goal to combine and develop techniques that allow the synthesis and organization of novel materials at multiple length scales in three spatial dimensions. The formation of such hierarchical assemblies from functional metal oxide building blocks with magnetic, optical, mechanical, electrical, or otherwise functional properties is a new approach. In the first stage of the project, nanoscale building blocks of arbitrary shape and composition will be made. Then, the building blocks will be functionalized or otherwise chemically altered to modify and control its covalent or non-covalent interaction with other building blocks. In the third stage, the building blocks will be assembled into a number of demonstrator materials, each with properties that emerge collectively from a spatially organized assembly of ?passive? building blocks without that specific property. The tool box of synthesis techniques that we intend to use in this project is unique, giving it the ability to tailor the development of functional building blocks in the best possible way. Pulsed Laser Deposition (PLD), a core expertise of the group, will be used to make inorganic nanoscopic objects of complex composition and shape by shadow mask deposition on sacrificial substrates. On the other hand, low-temperature soft chemical techniques (hydrothermal & microwave synthesis, sol-gel, templated synthesis of oxide nanowires) will be used to make monodisperse doped metal and metal oxide crystals, nanoparticles, rods and wires that are not accessible by high temperature techniques. To facilitate the vectorial (self)assembly of building blocks into 3D functional architectures with topological complexity, the building blocks made in the first phase of the project will be asymmetrically altered by PLD and/or micro contact printing techniques. The design principles will be demonstrated by constructing a number of 3D organized materials. Each of these demonstrators is made from primary units that carry part of the function, but only after their assembly the special properties emerge. Going down the list, there is a gradual increase in the expected complexity of achieving the targeted functionalities: (1) a material with anisotropic properties; (2) a composite material that combines two (or more) functional properties, from different building blocks; and (3) a material that responds via its internal organisation to external stimuli. |
