ALL-SOLID-STATE SODIUM-SELECTIVE ELECTRODES BASED ON ROOM-TEMPERATUREVULCANIZING-TYPE SILICONE-RUBBER MATRIX

Sodium-selective membranes based on room temperature vulcanizing-type silicone rubber (RTV-type SR) matrix and tert-butyl calix[4]arene-tetr aacetic acid tetraethyl ester (1.0 wt %) have been developed for all-s olid-state-type electrodes. It was observed that the potentiometric re sponse, stability and lifetime of these SR membrane-based all-solid-st ate electrodes critically depend on the type of lipophilic salts emplo yed. Among the several phenyl berate derivative-based additives examin ed, the SR membranes prepared with 0.5 wt % tetrakis[3,5-bis(trifluoro methyl)phenyl] berate salt (TFPB) exhibited low impedance, resulting i n electrochemical performance comparable to that of the PVC-based memb ranes mounted in conventional electrodes. The lifetime of all-solid-st ate electrodes with SR/TPFB/ tert-butyl calix[4]arene tetraethyl ester was longer than 230 days.