False morphology of aerogels caused by gold coating for SEM imaging

The imaging of non-conducting materials by scanning electron microscopy (SEM) is most often performed after depositing few nanometers thick conductive layers on the samples. It is shown in this work, that even a 5 nm thick sputtered gold layer can dramatically alter the morphology and the surface structure of many different types of aerogels. Silica, polyimide, polyamide, calcium-alginate and cellulose aerogels were imaged in their pristine forms and after gold sputtering utilizing low voltage scanning electron microscopy (LVSEM) in order to reduce charging effects. The morphological features seen in the SEM images of the pristine samples are in excellent agreement with the structural parameters of the aerogels measured by nitrogen adsorption-desorption porosimetry. In contrast, the morphologies of the sputter coated samples are significantly distorted and feature nanostructured gold. These findings point out that extra care should be taken in order to ensure that gold sputtering does not cause morphological artifacts. Otherwise, the application of low voltage scanning electron microscopy even yields high resolution images of pristine non-conducting aerogels.

Subjects

mesoporous materials

aerogels

electron microscopy

gold sputtering

aggregation

DDC Class

540: Chemie

Funding(s)

Advanced Engineering and Research of aeroGels for Environment and Life Sciences

Publication version

publishedVersion

Lizenz

https://creativecommons.org/licenses/by/4.0/

Name

polymers-13-00588.pdf

Size

16.05 MB

Format

Adobe PDF

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False morphology of aerogels caused by gold coating for SEM imaging