Grafting of ZrO2 powder and ZrO2 membrane by fluoroalkylsilanes

The hydrophobic properties of zirconia membrane have been obtained by grafting fluoroalkylsilane on the surface of the ceramic material. Several different grafting experiments were conducted using zirconia powders to determine the optimal conditions of grafting. The determined optimal conditions were then applied for the preparation of the hydrophobic membranes. The following grafting parameters were studied: the ratio of the amount of fluoroalkylsilane compound to zirconia mass in the grafting solution, the time and the temperature of grafting. Thermogravimetric analysis (TGA) was used as a technique for the characterization of the grafted powders. The TGA scans allowed to determine the grafting efficiency. The liquid entry pressure (LEP) and the water flux through the grafted membranes were also measured. The determined LEP and water fluxes proved that grafting process was very efficient. Contact angle measurements were additionally done to prove the hydrophobic character of the membrane surface. The hydrophilic character of ZrO2 membrane can be changed into a hydrophobic one by grafting 1H,1H,2H,2H-perfluorodecyltriethoxy-silane on the surface of the membrane. The performed experiments allowed to determine the optimal conditions of grafting process. Obtained membranes show good hydrophobic character. (C) 2004 Elsevier B.V. All rights reserved.