## 1 Introduction
The surface area of this monolith was comparatively low at 27.4 m\({}^{2}\)/g, but the authors concluded that the enhanced performance was actually due to the use of the multi-functional crosslinker which prevented the generation of gel-like micropores in the monolith globules which otherwise would result in high \(C\)-term values. An alternative strategy to increase nanoscale gel porosity is hypercrosslinking whereby poly(styrene-covinylbenzylchloride-_co_-divinylbenzene) monoliths are swollen in dichloroethane followed by Friedel-Crafts reaction with ferric chloride as catalyst at a temperature of 80 \({}^{\circ}\)C resulting in surfaces areas of several hundred m\({}^{2}\)/g and chromatographic efficiency \(>\)75,000 N/m [19; 20]. Monoliths modified with selected nanoparticles have also resulted in impressive chromatographic performance as detailed in several reviews on the subject [21; 22; 23; 24]. Traditional polymeric monoliths are formed by using a mixture of functional monomers, crosslinker, thermal or photo-initiators and appropriate porogen(s), leading to a traditional \"cauliflower-like\" morphology. A more recent method of polymer monolith fabrication is high internal phase emulsion (HIPE) templating. When a HIPE is formed, one phase is dispersed within the other in spherical droplet form, forming the \"internal phase\" and must be greater than 74% by volume [25]. In a water-in-oil (W/O) emulsion the water acts as the porogen and is dispersed in the organic phase (\"continuous phase\") which contains polymerisable monomers. This internal phase fraction (water) is known as the discontinuous phase since it is removed after polymerisation of the polyHIPE [25; 26]. The spherical macropores present due to the removal of porogen are known as voids (typically up to 10 \(\upmu\)m in size), and the interconnecting pores in the walls of the voids are referred to as windows (usually 1-2 \(\upmu\)m) [25]. The use of polyHIPEs in separation science has recently been reviewed [27] and is restricted mainly to the use of the crushed/powdered polyHIPEs for the extraction of analytes in batch mode, or their fabrication in flow through formats for low-efficiency trap-and-release cleanup of biological samples. Only very few examples of polyHIPEs for the separation of small molecules (\(<\)1000 Da) are reported and are worthy of discussion here. In 2010, [PERSON] _et al._ fabricated a 90% porosity isodecylacrylate-_co_-divinylbenzene polyHIPE in 100 \(\upmu\)m i.d. fused silica capillary and separated alkylbenzenes, yielding efficiency values in excess of 200,000 N/m when the monolith was operated in capillary electrochromatography (CEC) mode [28]. Later, in 2012, the same group investigated the application of PS-_co_-DVB polyHIPEs in CEC but reported a somewhat lower resolution and separation efficiency relative to their earlier work [29]. Recently, [PERSON] _et al._ formed PS-_co_-DVB polyHIPEs and EDMA polyHIPEs in 4.6 mm i.d. stainless steel column housings for the chromatographic separation of metal nanoparticles [30]. The monoliths were not bonded to the column wall and although 5 nm and 10 nm gold nanoparticles could be separated, peak symmetry factors exceeded 2.2 for each peak, and a very poor resolution of only 0.31 was achieved. When polymer monoliths have been used in separation science, either for liquid chromatographic or electrophoretic separations, the monolith has typically been formed within fused silica capillary or within the confines of a channel on a microfluidic chip (usually cyclic olefin co-polymer) [1]. In all cases, any useful monolith housing must obey two important criteria. Firstly, the diameter of the column/channel is usually <300 \(\upmu\)m because the heat generated during monolith polymerization is not easily dissipated when larger diameters are used, typically resulting in poor radial homogeneity of monolith density.