Emulsion-templated porous materials (PolyHIPEs) for selective ion and molecular recognition and transport: applications in electrochemical sensing

Functionalised emulsion-templated polymers (PolyHIPEs) are reported as new materials for electroanalytical applications. PolyHIPEs, which are prepared from high internal phase emulsions (HIPEs), were tailored by optimisation of polymerisation conditions to yield well-defined, tubular, porous membranes. The PolyHIPE membrane backbone was activated by incorporating ionophores, graphite particles, electron mediators and enzymes. The results show that a valinomycin ionophore impregnated, plasticised membrane shows a Nernstian response to K+ ions with improved detection limits and selectivity coefficients compared to traditional PVC membranes. The graphite/mediator/enzyme loaded membranes exhibit quasi-reversible redox behaviour with semi-infinite linear diffusion at fast scan rates tending to radial diffusion at slow scan rates. Additionally, composite, asymmetric membrane structures with a porous PolyHIPE membrane and a PVC membrane exclude proteins such as BSA (bovine serum albumin) and al acid glycoprotein (AAG). These preliminary results demonstrate that plasticised membranes with functionalised skeletons and with controllable porosity such as PolyHIPE membranes are very promising for the fabrication of sensors with integrated separation.