With their unique supermacroporous architecture, polyHIPEs (high internal phase emulsions) and cryogels have huge potential as analytical separation stationary phases.

The application of polymeric high-internal-phase emulsion (polyHIPE) capillary coatings for open-tubular analytical separation columns was demonstrated in this study for the first time. Multiple polystyrene-co-divinylbenzene polyHIPE layers with an average total depth of 1.73 mm were coated onto internal capillary surfaces to create open-tubular columns (20 cm coating and 32.5 cm effective length). With these columns for open-tubular capillary electrochromatography, ethylbenzene and pentylbenzene were separated. Although the overall separation capacity of the produced columns was low, the polyHIPE coatings improved the analyte peak shape, decreased the total run time, and improved the peak symmetries relative to comparable unmodified open-tubular columns. In addition, the use of these novel polyHIPE columns led to the use of 30% less organic modifier. These columns have the potential to improve the shelf life of open-tubular columns typically used in capillary electrochromatography. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44237.

Abstract:The reversed phase liquid chromatographic (RP-HPLC) separation of small molecules using a polystyrene-co-divinylbenzene (PS-co-DVB) polyHIPE stationary phases housed within 1.0 mm i.d. silcosteel columns is presented within this study. A 90% PS-co-DVB polyHIPE was covalently attached to the walls of the column housing by prior wall modification with 3-(trimethoxysilyl) propyl methacrylate and could withstand operating backpressures in excess of 200 bar at a flow rate of 1.2 mL/min. Permeability studies revealed that the monolith swelled slightly in 100% acetonitrile relative to 100% water but could nevertheless be used to separate five alkylbenzenes using a flow rate of 40 µL/min (linear velocity: 0.57 mm/s). Remarkable column-to-column reproducibility is shown with retention factor variation between 2.6% and 6.1% for two separately prepared columns.

This work presents the first instance of reversed-phase liquid chromatographic separation of small molecules using graphene oxide nanoparticle-modified polystyrene-divinylbenzene polymeric high internal phase emulsion (GONP PS-co-DVB polyHIPE) materials housed within a 200-µm internal diameter (i.d.) fused silica capillary. The graphene oxide nanoparticle (GONP)-modified materials were produced as a potential strategy to increase both the surface area limitations and the reproducibility issues observed in monolithic stationary phase materials. GONP PS-co-DVB polyHIPEs were found to have a surface area up to 40% lower than unmodified polymeric high internal phase emulsion (polyHIPE) stationary phases. However, despite having a surface area significantly lower than that of the unmodified material, the GONP-modified polyHIPEs demonstrated superior analyte adsorption properties. Reducing the GONP material did not have any significant impact on elution order or retention factor of the analytes, which was most likely due to low GONP loading attributed to the 250-nm GONPs utilised. The lower surface area of GONP-modified polyHIPEs provided similar separation efficiency and increased repeatability from injection to injection resulting in % relative standard deviations (%RSDs) of less than 0.6%, indicating the potential offered by graphene oxide (GO)-modified polyHIPES in flow through applications such as adsorption or separation processes.