[Preparation and modification of polyhedral oligomeric silsesquioxane-containing hybrid monolithic capillary columns]

Two kinds of hybrid monolithic capillary columns were prepared via free radical polymerization. First, the hybrid monolithic column was in situ fabricated by using two polyhedral oligomeric silsesquioxanes (POSS), POSS-methacryl substituted (cage mixture, n = 8, 10, 12) (POSS-MA) and POSS-(1-propylmethacrylate)-heptaisobutyl substituted (Bu-POSS), as crosslinker and monomer, respectively, in the presence of porogenic solvents (propanol/ PEG400) and initiator (azodisobutyronitrile). Second, the hybrid monolithic column was similarly prepared by using POSS-MA, as sole monomer under the same conditions. The resulting two kinds of hybrid monolithic columns, poly (Bu-POSS-co-POSS-MA) and poly (POSS-MA), were characterized and applied for the separation of alkylbenzenes by capillary liquid chromatography (cLC), showing good mechanical stability and reproducibility. Additionally, the poly (POSS-MA) monolith could be easily modified with other organic monomers, such as stearyl methacrylate (SMA) and benzyl metacrylate (BeMA), with the presence of methacryl groups on the surface of the poly(POSS-MA) monolith. Compared with the raw poly(POSS-MA) monolith, the post-modified poly(POSS-MA) monolith exhibited higher column efficiency and better selectivity. This simple process of using POSS reagents via free radical polymerization is providing a novel way for the preparation of the organic-silica hybrid monolithic columns.