Separation resins are disclosed where silica particles are surface activated by attaching a vinyl terminated lower alkoxy silane to the silica particle and then hydrolyzing the particles. The resulting hydrolyzed particles are hydrophilic and retain at least 10 micromoles of the hydrolyzed vinyl terminated lower alkoxy silane per square centimeter of the silica. A water soluble polymer is then graft polymerized onto the activated and hydrolyzed silica particles. The large amount of hydrolyzed vinyl terminated lower alkoxy silane which remains on the silica along with the hydrophilic nature of the hydrolyzed silica produces an activated particle which is useful for graft polymerization of water soluble polymers onto the particles in large amounts not previously possible. A method for preparing the separation resins is also disclosed.