Reinforcing polymer cross-linked aerogels with carbon nanofibers

We have previously reported cross-linking the mesoporous silica structure of aerogels with di-isocyanates, styrenes or epoxies reacted with amine decorated silica surfaces. These approaches have been shown to significantly increase the strength of aerogels with only a small effect on density or porosity. Herein, we examine the effect of including up to 5% (w/w) carbon nanofibers in the silica backbone before cross-linking. The addition of 5% carbon nanofibers to the lowest density aerogels studied triples the compressive modulus and the tensile stress at break is increased five-fold with no density penalty. The carbon fiber also improves the strength of the initial hydrogels before cross-linking, which may have implications in manufacturing.