Silica Aerogels: A Review of Molecular Dynamics Modelling and Characterization of the Structural, Thermal, and Mechanical Properties

Samuel S. Kistler showed that extremely porous silica aerogels can be made from supercritical drying of wet gels. This work, along with subsequent experimental and simulation studies, eventually led to the commercialization of silica aerogels in numerous engineering applications, especially for thermal insulation in aerospace and civil engineering applications. Rapid progress in the synthesis of silica aerogels provided great impetus for characterizing and optimizing their molecular structures. This created significant numerical challenges in understanding their structure-property-function relationship at several hierarchies of length scales. Both fully atomistic and coarse-grained molecular dynamics modeling and simulations have been extensively developed to tackle these challenges. We reviewed the development of new empirical molecular dynamics forcefields, novel methods of generating aerogels’ percolated backbones, and compelling algorithms for characterizing their structural, mechanical, and thermal properties that have resulted in unprecedented insights into silica aerogels. These developments will drive the eventual creation of a comprehensive set of multiscale modeling platforms, which can minimize the trials and errors during experimental synthesis and even bring silica aerogels into the fold of the materials-by-design paradigm.