IR STUDIES OF ADHESION PROMOTERS .3. ADSORPTION AND COUPLING OF BIFUNCTIONAL SILANES ON SILICA AT THE SOLID-LIQUID INTERFACE

IR spectra are reported of silica immersed at 293 K in carbon tetrachl oride solutions of the silane coupling agents 1-aminopropyltrimethoxys ilane and 3-glycidoxypropyltrimethoxypropane and the bonding reagents epoxypropane and 1-aminopropane. Negligible chemisorption or chemical reaction occurred. Dominant surface-adsorbate interactions involved co mpetition between different functional groups in solute molecules for the formation of hydrogen bonds with isolated silanol groups on the si lica surface. The coupling agents underwent changes in orientation in the adsorbed state with increasing surface coverage. These changes cou ld also be induced by co-adsorbates. Adjacent interacting silanol grou ps on silica were less likely than isolated silanol groups to act as a dsorption sites.