Formation of graphitic carbon nanofiber (GCNF)/silica gel composites using surface-functionalized GCNFs and sol-gel processing

Abstract

Reaction of herring-bone graphitic carbon nanofibers (GCNFs) containing surface-bound acid chloride functional groups with 3-aminopropyl triethoxysilane (APTES) leads to amide condensation and formation of carbon nanofibers surface-derivatized with pendant Si—OEt and Si—OH functional groups, GCNF-[C(O)NH(CH2)3Si(OEt)(OH)2] x . Addition of these GCNFs containing covalently bound 3-amidopropylsilyl linker molecules to silica sol-gel formulations gives GCNF/silica xerogels as dry black powders. Covalent binding of the linker molecule across the GCNF/ceramic interface is indicated by intermediate formation of especially stable GCNF/silica sol dispersions and the isolation of uniformly black GCNF/silica xerogel powders. SEM micrographs reveal excellent wetting of the carbon nanofiber surface by the silica xerogel matrix, and the presence of amido-carbonyl groups is confirmed from infrared spectral data. TGA plots show mass losses consistent with dehydration of the gel matrix and thermal decomposition of linker molecules at elevated temperature.