Simulation of the grafting of organosilanes at the surface of dry amorphous silica

We have performed first principles metadynamics simulations of the grafting process of tetraethoxysilane (TEOS) at two surface sites of dry amorphous silica: the two-membered silicon ring and the isolated silanol. The ab initio activation energies for the grafting reaction are 0.2 eV and 1.4 eV, at the 2M and SiOH sites, respectively. The simulations support the experimental evidence based on IR vibrational spectroscopy that the ring is more reactive than the surface SiOH group for the grating of organosilanes.