Thermal transport in colloidal alloys

• Applicant: Professor Dr. Markus Retsch
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 317822884

Thermal transport through densely packed particle beds is of great technological relevance for the development robust insulation materials. The goal of this project is the fundamental investigation of thermal transport in densely packed particle ensembles comprising two distinctly different types of spheres; such mixed ensembles can be termed colloidal alloys. Current granular systems consist of micron-sized, irregular shaped and polydisperse grains. Particle beds derived from them are consequently random and ill-defined structures. This impedes the analytical description and predictability of such particles beds, for which quite commonly effective medium theories are applied. On the contrary, colloidal superstructures have been far less investigated and are typically built from well-defined, spherical objects with sizes ranging from 100 nm to a few micrometer. Therefore, full control of the packing density and symmetry is retained. Furthermore, particles of vastly differing thermal conductivity such as amorphous polymers or silica and electrically conducting metals can be incorporated. We will therefore self-assemble polymer and silica particles with metallic capsules into well-defined colloidal superstructures. This enables us to specifically investigate the influence of both, composition and structure, on the thermal conductivity in such binary particle mixtures. To achieve this goal, polymer, silica and metal particles will be tailor-made with respect to their size, functionality and density. These particles will then be self-assembled into colloidal crystals and glasses with a pre-defined mixing ratio. We will specifically investigate the evolution of percolation pathways. This systematic approach allows establishing of structure-property relationships for the fundamental understanding of nanoscale thermal transport in particle ensembles. These results may be further adapted to the characterization of existing granular matter.

• DFG Programme: Research Grants
• Major Instrumentation: Dynamische Differenzkalorimetrie
• Instrumentation Group: 8660 Thermoanalysegeräte (DTA, DTG), Dilatometer