A New Type Of Hybrid Aggregation Model And The Application Towards Silica (Aero)gels

Abstract

A new type of hybrid aggregation model and the application towards silica (aero)gels Nina Borzęcka, Prakul Pandit, Ameya Rege Department of Aerogels and Aerogel Composites, Institute of Materials Research, German Aerospace Centre, Cologne, Germany

Silica aerogel modelling requires acknowledging the complexity of their structure. The condensation of the classic particle aggregates type of aerogel is a complex phenomenon which result in their final nanostructured porous morphology. In order to understand the process, a comprehensive and multiscale approach is needed. A widely utilised, although significantly simplified approach for modelling sol-gel transition is diffusion or reaction limited cluster aggregation method (DLCA/RLCA). This type of numerical system can mimic random motion of primary/secondary particles and follow simultaneously the structure evolution and the kinetics of its formation. The model parameters such as concentration of secondary particles and sticking probability affect the process rate and the structural and fractal properties. As a consequence, we introduce a modelling approach, that takes into the consideration the numerical particle reactivity based on the experimental reaction rates. The comparison of numerical and experimental results provides data for model validation and discussion whether these improvements bring us closer to reflecting the real materials – silica aerogels. Which brings us to the question: Does such a modelling approach show potential for reverse engineering and product design?