A New One-Step CCVD Technique for the Production of MWCNT Aerogels
Доклады на конференциях
MWCNT aerogels combine unique properties of their basic building element with related characteristics of aerogel structure. Here we report a new one-step approach for MWCNT aerogel production via CCVD technique by using a preformed catalyst. It based on multi-centered growth of MWCNTs provided by formation of multiple nanosized catalytic centers on the surface of the support particle. Tangling of the MWCNTs during the following growth provides formation sponge-like structure of aerogel. Due to intensive nanotube growth, a volume of resulting material increases a hundred times in comparison with a volume of preformed catalysts. This results in the formation of aerogels with density of 0.03-0.08 g/cm3. Any shape of aerogels is possible to obtain by using different geometry of preformed catalysts (balls, cylinders etc.). In situ produced MWCNT aerogels demonstrate high electrical conductivity (several S/cm), remain stable in different solvents and hold more than 2000 their wieght. Pores of size >120 nm occupy >95% of aerogel volume whereas smaller pores take up <2%. MWCNT aerogels show electric polarizability values close to metals while having a substantially lower weight (8-12 GHz). Due to rigid, tunable shape and pore structure, MWCNT aerogels are promising for such applications as EMI and acoustic shielding materials, gas sensors and substrates for biological objects.