Preparation and characterization of functionalized precipitated silica SYLOID® 244 using ionic liquids as modifiers

Studies were performed on the chemical modification of SYLOID^® 244 (Grace) precipitated silica using ionic liquids. The unmodified and ionic‐liquid‐functionalized silica were subjected to a comprehensive physicochemical and dispersive evaluation. Particle size, polydispersity and specific surface area (BET) and porous structure were examined. Moreover, stability of the colloids obtained was evaluated by estimation of isoelectric points. The extent of modification and its type were defined using fourier transform infrared spectroscopy and ²⁹Si‐cross‐polarization/magic angle spinning/nuclear magnetic resonance techniques. The modification was not observed to deteriorate the dispersive properties of the silica. The silicas obtained exhibited a restricted tendency to form larger accumulations of particles, i.e. aggregates and agglomerates. Moreover, application of ionic liquids with a heptyloxymethyl or octyloxymethyl substituent resulted in complete hydrophobization of the silica surface. Tested powders manifested the highest stability within a pH range of 10–12. Copyright © 2004 John Wiley & Sons, Ltd.