STRUCTURAL INVESTIGATIONS OF PYROLYZED ORGANICALLY MODIFIED SIO2 AEROGELS

Nanoporous SiO2 aerogels are modified by integration of phenyl groups into the surface of the SiO2 skeleton. In a pyrolysis process with temperatures up to 1000 degrees C, the phenyl groups are transformed into carbon structures. This process is observed via IR spectroscopy in the wavelength range from 2.3 to 8.0 mu m. Small-angle X-ray; scattering and Brunauer. Emmett and Teller (BET) measurements as well as transmission electron micrographs support the structural investigations. Raman spectra show the occurrence of graphitic and disordered carbon structures, The concentration of the latter increases with the duration of the pyrolysis process. The investigations indicate a homogeneous carbon distribution and a partial coating of the SiO2 primary particles with nanometer thin carbon films.