Indiana University

Vladislav Dolnik

Milos V Novotny

Kelly A Cobb

Surfaces of silica-containing materials, such as the inner walls of silica capillaries, used in chromatographic, particularly electrophoretic, separations are coated with an organic polymer 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 reagent having a terminal ethenyl moiety, preferably vinyl or allyl lithium or a vinyl or allyl magnesium halide, to convert the silicon halide groups to Si--R groups where the R retains the terminal ethenyl moiety, and finally reacting these ethenyl groups newly attached to the surface with a neutral organic monomer in an addition polymerization reaction to form a monomolecular noncrosslinked polymer layer over the surface. The resulting polymer layer is linked to the silica directly through a Si--C bond which is stable over a wide range of pH conditions.

Suppression of electroosmosis with hydrolytically stable coatings

Gels are formed in capillary tubes by electrophoretically drawing a charged polymerization initiator into a capillary tube pre-filled with monomer, crosslinking agent and catalyst. The rate of travel of the initiator is slow enough to maintain a sharp leading edge or front, thereby causing polymerization to occur in a progressive manner from one end of the capillary to the other. The shrinkage inherent in the polymerization reaction is thus compensated by fluid movement ahead of the traveling initiator front, and discontinuities in the gel which would otherwise be formed are avoided.

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Brno, Czechia

Vladislav Dolnik