Chromatographic efficiency comparison of polyhedral oligomeric silsesquioxanes-containing hybrid monoliths via photo- and thermally-initiated free-radical polymerization in capillary liquid chromatography for small molecules

• Both photo- and thermal-polymerization for preparing hybrid monoliths were compared.
• POSS-containing monoliths could be prepared within 10 min via photo-polymerization.
• Photo-polymerized hybrid monoliths exhibit higher column efficiency.

Monolithic poly(methacrylate epoxy cyclosiloxane-co-polyhedral oligomeric silsesquioxanes) (epoxy-MA–POSS) capillary columns have been prepared via either photo- or thermally-initiated polymerization of the corresponding monomers using a 1-propanol/PEG 400 mixture as porogens. Photochemical polymerization was accomplished by irradiation of the UV-transparent capillary for 10 min at room temperature, while thermal polymerization was performed at 55 °C, 60 °C or 65 °C for 18 h. The evaluation of chromatographic property for two hybrid epoxy-MA–POSS monoliths was carried out. The results indicate that hybrid monoliths fabricated by photochemical initiation exhibit higher column efficiency (97,000–98,400 plates/m) than those synthesized by thermal polymerization (41,100–48,000 plates/m) in cLC. The higher efficiency of photo-initiated hybrid monoliths is closely related to lower eddy dispersion (A-term) and mass transfer resistance (C-term).