Silicon functionality distribution on the surface of amorphous silicas by 29Si solid state NMR

Abstract Using 29 Si solid state nuclear magnetic resonance and particularly cross-polarization, magic angle spinning and dipolar dephasing spectra, the distribution of species at the surface of different amorphous silicas was investigated. A regular evolution of single versus geminal silanols was interpreted as the result of some equilibrium of the functional groups. The deviation from this scheme which appears for pyrogenic silica was shown by dipolar dephasing to be due to strained defects among the siloxane bridges.