Porous polystyrene-based monolithic materials templated by semi-interpenetrating polymer networks for capillary electrochromatography

Porous polystyrene-based monolithic columns were engineered through the in-situ generation of poly(ɛ-caprolactone) (PCL)/polystyrene (PS) semi-interpenetrating polymer networks (semi-IPNs), followed by the extraction of the uncrosslinked partner acting as a polymeric porogen. In a first stage, the semi-IPNs were prepared within the confines of fused silica capillaries by UV-initiated free-radical copolymerization of styrene and divinylbenzene, in the presence of PCL oligomers. In a second stage, the quantitative extraction of uncrosslinked oligoesters led to the formation of porous frameworks with a hierarchical porosity, as evidenced by SEM and DSC-based thermoporometry. Such as-obtained porous monoliths could be efficiently used as reversed-phase stationary phases for the separation of alkyl benzene derivatives by capillary electrochromatography (CEC).