IR STUDIES OF ADHESION PROMOTERS .1. METHOXYTRIMETHYLSILANE ON SILICAAT THE SOLID-LIQUID INTERFACE

The adsorption of methoxytrimethylsilane on silica immersed in heptane or carbon tetrachloride primarily involves hydrogen-bonding interacti ons between surface silanol groups and the O atoms of MeOSiMe(3) molec ules. A 1:1 interaction is dominant for isolated SiOH groups but adjac ent interacting pairs of silanol groups adsorb a single silane molecul e at low adsorbate concentrations, changing to pairs of silane molecul es with increasing concentration. Hydrogen-bonded silane is removed fr om the surface by evacuation at 293 K but removal of solvent initially promotes a low level of chemisorption resulting in -SiOMe and -SiOSiM e(3) on the silica.