| Abstract
| - Aerogels (AGs) are ultralow-density nanoporous solids that have numerous potential applications. However, asmost AGs are strong insulators with poor mechanical properties, direct studies of the complex nanoporous structureof AGs by methods such as atomic force and conventional scanning electron microscopy (SEM) have not provenfeasible. Here, we use low-vacuum SEM to image directly the ligament and pore size and shape distributions ofrepresentative AGs over a wide range of length scales (∼100−105 nm). The structural information obtained is usedfor unambiguous, real-space interpretation of small-angle X-ray scattering curves for these complex nanoporoussystems. Low-vacuum SEM permits imaging of both cross-sections and skin layers of AG monoliths. Images of skinlayers reveal the presence of microcracks, which alter the properties of cast monolithic AGs.
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