| abstract |
Surfaces of materials containing silica, such as the internal walls of silica capillaries, used in chromatographic separations, particularly for electrophoresis, are coated with an organic polymeric layer to reduce or eliminate surface charges. The layer is applied by first converting the silanol groups on the surface to silicon halide groups, then reacting these groups with an organometallic reactant having an ethenyl end part, preferably vinyl-lithium or allyl-lithium or a vinyl-magnesium halide or allyl magnesium, to convert the silicon halide groups to Si-R groups in which the Rs retain the ethenyl end part and finally reacting these ethenyl groups again attached to the surface with a neutral organic monomer in an addition polymerization reaction for the purpose of form a cross-linked cross-linked monomolecular polymeric layer on the surface. The resulting polymeric layer is crosslinked directly to the silica through a Si-C bond which is stable over a wide range of pH conditions. |