Multi-scale numerical modeling of condensation and mechanical properties of organosilica-based aerogels

• Applicant: Professorin Dr. Barbara Milow
• Subject Area: Computer-Aided Design of Materials and Simulation of Materials Behaviour from Atomic to Microscopic Scale ; Synthesis and Properties of Functional Materials
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 524816202

New challenges of science and technology result from the intensive search for new materials with unique properties. A thoroughly studied example in recent years are aerogels, named one of the Top Ten Emerging Technologies by IUPAC in 2022. These materials can be obtained from different precursors: cellulose, metal oxides, even graphene, but one of the most widely researched and widely used types of aerogels in technology are those obtained on the basis of organosilica in a sol-gel process. Aerogels are characterized by low density (usually of the order of several kg/m3), high porosity (up to 99.8%), high specific surface area (up to 1000 m2/g) and many other unique physical and physicochemical properties. These can be influenced by the appropriate selection of precursors, the composition of the reaction mixture and the parameters of the manufacturing process itself (e.g. process temperature, selection of the appropriate drying method. There are some disadvantages, primarily due to their mechanical properties - aerogels are often characterized by poor tear strength and high brittleness. The aim of the project is a method of producing silica aerogels with given mechanical and morphological properties and allow prediction of the finished product through cheaper numerical methods than many sets of experiments. For this, the formation of the aerogel from the precursor molecules to the macroscopic material with specific properties needs to be traced. To do this, a wide range of sizes from single atoms and molecules to macroscopic aerogel fragments needs to be considered. Such a large range of sizes cannot be modeled with a single algorithm - a multi-scale model is needed, consisting of various numerical procedures, each of which is appropriate for individual size scales. Creating such a model is the goal of this project. In details, our model will cover the aerogel formation at three levels: chemical molecules, physical particles and whole network. At each scale and at each stage of the aerogel production process, the models will be supported by various tests using spectroscopy (UV-Vis, DLS, FT-IR and Raman), microscopy (electron or optical), rheometry and porosimetry. Also the mechanical properties of aerogel will be investigated. The final result of the project will be a model allowing for full description of the dependence of aerogel synthesis parameters on the kinetics of aerogel formation and its final structural properties. Only a comprehensive and broad view of both experimental and model approaches can result in a fundamental understanding of the nature and properties of the resulting materials. The project will allow to obtain aerogels with controlled and pre-designed properties and to optimize the manufacturing process. All tests and the obtained results will allow the evaluation of the obtained materials in terms of future applications.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Professor Jakub M. Gac