Investigation of temperature-responsivity and aqueous chromatographic characteristics of a thermo-responsive monolithic column

A thermo-responsive and macroporous monolithic cryogel was directly prepared by in situ free-radical redox cryo-polymerization in a stainless steel chromatographic column (100 mm × 4.6 mm i.d.) using N-isopropylacrylamide (NIPAAm) as functional monomer and PEG-20,000 as porogen at −12 °C. The internal morphology of resulting monolithic cryogel was estimated by scanning electron microscopy (SEM). Based on that, a submicron skeleton structure was observed. Besides, the gravimetrically determined rates of swelling/deswelling for thermo-responsive monolithic cryogel were much higher than that of hydrogel adopting the same component proportion via conventional method (25 °C for 24 h). Simultaneously, a temperature-dependent resolution of steroids was also achieved using only water as a mobile phase. The theoretical plate number of every analyte was more than 2000.