Facile preparation of ambient pressure dried aerogel-like monoliths with reduced shrinkage based on vinyl-modified silica networks

Ambient pressure dried aerogel-like monoliths were prepared with a simple route, without requiring additional steps. Three formulations of vinyl-modified silica porous structures were studied: one derived from vinyltrimethoxysilane, a second from a mixture of vinyltrimethoxysilane and methyltrimethoxysilane, and another from vinyltrimethoxysilane, methyltrimethoxysilane and tetramethyl orthosilicate. It was found that the presence of the vinyl groups prevents network shrinkage during the drying step, allowing a maximum linear shrinkage of 11%. The obtained materials were found to feature aerogel-like properties: they are light (bulk density <= 183 kg m(-3)) and retain high porosity (> 91%). It was shown that their porosity is mainly due to a predominant amount of large pores. Other remarkable properties of the obtained materials are their high hydrophobic nature (theta >= 139 degrees) and flexibility (E <= 108 kPa).