Designable size exclusion chromatography columns based on dendritic polymer-modified porous silica particles

Dendritic polymer-modified porous silica particles prepared by a poly(amidoamine) (PAMAM) dendrimer synthesis reaction were characterized by elementary analysis (EA) and size exclusion chromatography (SEC). EA demonstrated the successful alternate growth of dendritic layers on the particles. The phased growth of polymer moieties by cascade reactions filled mesopores on the silica particles and decreased the exclusion limit molecular weight (M-lim) step by step. The density of the dendritic polymer moieties was affected by the reaction conditions, such as reaction time, temperature, and generation. The mesopore size on the particles, indicated as M-lim, was controlled by the grafting ratio, which could be adjusted by the reaction conditions. Furthermore, the elution behaviors of SEC standard samples with a M-w lower than the M-lim were governed by the local microstructure of the dendritic polymer moieties on the silica particles, most notably by polymer density. It was found that the local microstructure of the dendritic polymer moieties could also be controlled by the reaction conditions.