Springback effect of ambient-pressure-dried silica aerogels: nanoscopic effects of silylation revealed by in situ synchrotron X-ray scattering

Abstract

During ambient pressure drying of silica aerogels, shrinkage and re-expansion is observed, commonly known as the springback effect. In situ synchrotron X-ray scattering gives insights into the nanostructural evolution of drying gels.

Solvent Cavitation during Ambient Pressure Drying of Silica Aerogels

“…In silica gels modified with a silylating agent such as trimethylchlorosilane (TMCS), this coincides with a re-expansion of the solid matrix, enabling recovery of the drying shrinkage known as the spring-back effect (SBE) and resulting in hydrophobic aerogels . The SBE is a key feature in the production of aerogels by evaporative drying and its origin has not been investigated until recently. ,− Nevertheless, it is not yet understood how monolithic silica aerogels can be produced by evaporative drying considering the extreme stress exerted on the silica solid matrix by drying shrinkage and spring-back, which therefore challenges the current models of evaporative drying.…”

“… 1 The SBE is a key feature in the production of aerogels by evaporative drying and its origin has not been investigated until recently. 10 , 35 − 38 Nevertheless, it is not yet understood how monolithic silica aerogels can be produced by evaporative drying considering the extreme stress exerted on the silica solid matrix by drying shrinkage and spring-back, which therefore challenges the current models of evaporative drying.…”