The buckling deformation and mechanical properties of aerogels prepared with polyethoxydisiloxane

• Synthesis of aerogels with hierarchical nanostructures.
• Research of mechanical properties of hierarchical nanoporous aerogels.
• Research of the correlation of mechanical properties and nano-pore size.
• Building a model of hierarchical nanoporous aerogel according to the mechanical parameters of aerogels.

The high-polymeric degree or molecular-weight of self-made polyethoxydisiloxane (PEDS) was successfully used to synthesize aerogels with several advantageous mechanical characteristics, compared with those based on conventional tetraethylorthosilicate (TEOS) aerogel preparation methods. The first advantage is their lower initial values of bulk modulus (K0), compared with those prepared via the two-step method; this is due to release of internal stress during the shrinkage of wet gel. Secondly, a collapse index n of −0.125 is obtained by the collapse law; this implies a new buckling destruction model. This is different from those prepared via the two-step method, and suggests that a hierarchical filament structure, formed by the connection of nano-particles, constitutes the solid skeleton of pores. In this paper, average aerogel pore sizes between 16.0 and 39.3 nm are analyzed by the combination of Mercury Intrusion Porosimetry (MIP) and Nitrogen Adsorption–Desorption (NAD). The microstructure and morphology of the aerogels are demonstrated by Transmission Electron Microscopy (TEM) and Field Emission Scan Electron Microscopy (FE-SEM).

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