A novel and highly effective method for forming a thin layer of surface-confined hyper-crosslinking (HC) polymer networks on a silica substrate was developed. Microparticulate silica is widely used substrate for high performance liquid chromatographic (HPLC) stationary phases. The HC stationary phases were prepared with the formation of HC networks through orthogonal chemistry, which provides the high acid stability, and then the derivatization generated different types of phases. There after, acid washing was used as a post-synthesis pre-treatment under highly acidic conditions to completely convert all residual labile bonds to stable species. The key concept of the whole approach was the polymerization and the crosslinking of the surface bonded ligands into extensive networks by the use of the orthogonal reaction chemistry. The silica-based stationary phases synthesized by this approach show acid stability better than that of sterically protected type C18 phases.
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Acknowledgements This work was supported by a grant from the National Institutes of Health. The authors wish to thank Leo Ma, Jun Dai, and Yu Zhang for many helpful discussions