| Abstrakt: |
A technique for modifying the natural water-wetting behavior of polished quartz plates is discussed. The method involves chemical bonding of an organoaminosilane in the vapor phase to hydroxyl groups at the quartz surface. The dynamic Wilhelmy plate apparatus provided rapid and convenient evaluation of the silylation reactions. Three different silylation temperatures were investigated for both monofunctional hexamethyldisilazane (HMDS) and bifunctional bis(dimethylamino)dimethylsilane (BDMADMS). With both types of silane, only experiments at the highest temperature, 275°C, resulted in new siloxane bonds at the surface and, hence, strongly oil-wetting behavior. The persistence of the modified surfaces upon immersion of the plates in water varied considerably with the type of silane used. The surface of the HMDS-treated plates started to degrade within 24 h after soaking the plates in water. Plates treated with BDMADMS remained oil wetting in both directions of the wetting cycle for up to 13 weeks of soaking in water and at least 9 additional weeks when soaked in other liquids. Copyright 1994, 1999 Academic Press |
