Supermacroporous polyHIPE and cryogel monolithic materials as stationary phases in separation science: a review

With their unique supermacroporous architecture, polyHIPEs (high internal phase emulsions) and cryogels have huge potential as analytical separation stationary phases. Due to their fully interconnected pore structure, mass transfer occurs predominantly via convection, potentially allowing for enhanced chromatographic performance. Additionally their surface functionalities can be tailored by modification of substrates both during and post fabrication. Their surface area is typically lower than comparable particulate stationary phases and problems with their rigidity persist. For these reasons, apart from their applications for large biomolecule analysis, the potential of cryogel and polyHIPE materials as separation phases in separation science have not been extensively realised. However, multiple strategies exist to overcome these limitations, potentially enabling the application of cryogels and polyHIPEs for a diverse range of separations. Current applications, such as chelation resins, which demonstrate the diverse interaction modes of both supermacroporous substrates, and applications of both substrates in analytical separations are considered in this review. Additionally the limitations of these technologies are explored, and strategies to overcome these limitations and further develop these monolithic phases for analytical separations are presented.