Polymer based monoliths were introduced about 20 years ago. The relatively simple preparation, robustness, high permeability to flow, mass transfer via convection and flexible chemistry has since seen these materials used in a range of applications such as chromatography and as supports for synthesis, catalysis and immobilized enzymes. A key factor in improving the performance of polymer monoliths, in particular for analytical applications is the degree of bed heterogeneity. This presentation will introduce a number of approaches we have recently demonstrated to form ordered porous polymers with improved bed heterogeneity, suitable for analytical applications including chromatography, sample preparation and as supports for immobilized enzymes. Polymerization at sub-zero temperatures (cryopolymerisation) with and without unidirectional freezing is shown to produce highly ordered monolithic structures with porous properties that can be easily tuned according to the freezing/polymerization conditions. The incorporation of nanoparticles (neutral or charged polymer, inorganic, metal) during the polymerization process also leads to significantly improved structural homogeneity, reflected in chromatographic separation performance. Examples of new interconnected polymerized high internal phase emulsions (polyHIPEs) and medium internal phase emulsions (polyMIPEs) will also be presented. A range of different emulsion stabilizers including nanoparticles, novel amphiphilic block co-polymers and surfactants will be demonstrated, resulting in control of both the morphology and surface chemistry. Techniques for the physical and chemical characterization of these novel monolithic materials will also be introduced. For example. scanning transmission X-Ray microscopy (STXM), a synchrotron-based microscopy technique providing information about the spatial distribution of chemical components at sub-50 nm spatial resolution based on near edge X-ray absorption fine structure spectral (NEXAFS) contrast will be shown to be a powerful tool for the high resolution characterization of these materials.

Preparation and characterisation of ordered porous polymer monoliths

248th National Meeting (2014)

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