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

Abstract

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.