EVALUATION OF POLYURETHANE-BASED MEMBRANE MATRICES FOR OPTICAL ION-SELECTIVE SENSORS

Plasticized thin films of polyurethane (PU) mixed with poly(vinyl chlo ride)(PVC) or a terpolymer of poly(vinyl chloride)/(vinyl acetate)/(vi nyl alcohol) (PVA) are examined as membrane matrices for the preparati on of reversible optical ion sensors. Optical sensors for Na+, NH4+, C l-, and ClO4- are prepared by casting thin films of the polymer mixtur es (PU/PVC (1:1 wt) and PU/PVA (4:1 wt)) containing appropriate ion ca rriers and pH chromophores on glass slides. The optical response prope rties of these membranes is essentially the same as conventional pure PVC membranes reported in the literature. However, significantly enhan ced membrane adhesion to glass or silicon wafer surfaces is observed u sing the polyurethane based matrices, making them more suitable than P VC for use in the development of solid-state optical ion sensing devic es.