The particular innovative potential of the SFB 986 is its ability to develop macroscopic materials – structured in a multi-scale way, designed “on the drawing board”. Owing to their design, such materials will have tailor-made mechanical, electrical, and photonic properties. Predominantly, the materials are assembled from single building blocks of distinct discrete length scales. This hierarchical composition opens up possibilities to exchange building units in a concerted way in order to discretely alter materials properties and, thus, to achieve entirely new materials functions.
The materials used in the three project areas A, B, and C of the SFB 986 are very different from "classical" materials due to their individual hierarchical microstructure. Classically, one designs a material's microstructure by a heat treatment together with simultaneous mechanical deformation. Step by step, small changes of a material's structure, chemical composition, and self-organization effects (e.g., precipitation alloys, glass ceramics, eutectic microstructures) result in a continuous optimization of the material. For centuries, this strategy has produced extremely efficient materials; yet, the number of possible geometries remained quite restricted. The research program of the SFB 986 aims at a tailor-made production of complex, multi-scale and/or hierarchical microstructures by controlled synthesis and assembly processes used in chemistry, materials science, and process engineering.
In this sense, the SFB 986 will start with elementary functional units and fabricate macroscopic hierarchical materials systems made from polymer, ceramics, metals, and carbon (in form of carbon nanotubes and aerographites), thereby bridging length scales from the atomistic to the macroscale (see figure). Those elementary functional units are core-shell structures or, in metals, cavities formed by alloy corrosion and filled with polymers.
The three project areas of the SFB 986 use different materials systems and vary both the multi-scale structure and the functionalized properties: area A is concerned with quasi-self-similar structures with multi-functional properties; area B aims at integrated nano-structured multi-phase materials systems, which – due to the design of their microstructure – combine strength and functional properties (in particular, electrical ones); and area C focuses on highly ordered, hierarchical, periodic and aperiodic structures and their photonic properties at high temperatures.
One question unites all three project areas: How can we influence and control the macroscopic mechanical, electrical, and photonic properties of materials by shaping their hierarchical composition? By answering this question, the SFB 986 can develop hierarchical materials with tailor-made properties in a systematic way.