Grafting of selected presynthesized macromonomers onto various dispersions of silica particles

A new process was developed which enables one to obtain surface-modified silica with a high heavy metal ion complexing ability. The synthetic approach is based on grafting of vinyl-terminated macromonomers onto silica via covalent bonding. A proper selection of the macromonomer structure, molecular weight, and molecular weight distribution allows materials to be obtained with a range of desirable properties. The process has been tested on various dispersions (ranging from 35 and 200 pm) of silica particles and two structurally related macromonomers. Native silica and the resulting mixed organic-inorganic products were fully characterized by IR spectroscopy, SEM, yield of grafting (elemental analysis and calcination), density (helium pycnometry), specific surface area (BET method), and pore size (gas adsorption and mercury porosimetry) measurements. It was found that the corresponding polymers are effectively grafted onto the surface; the density, surface area, and pore size of the silica particles decrease with polymer grafting. Preliminary results on metal-ion uptake indicate that polymer-grafted silica exhibits an excellent complexing ability.