DURABLE NITRATE-SELECTIVE CHEMICALLY-MODIFIED FIELD-EFFECT TRANSISTORS BASED ON NEW POLYSILOXANE MEMBRANES

Polysiloxane copolymers with different amounts and types of substituen ts have been synthesized and characterized. Polar substituents determi ne the polarity and methacrylate groups allow cross-linking and covale nt binding of electroactive species. These chemically well-defined hom ogeneous polymers have been applied as ion-selective membrane material in nitrate-selective field effect transistors (CHEMFETs). The selecti vity of the CHEMFETs is influenced by the nature of the polar substitu ents in the polymer. The incorporation of methacrylate moieties in the polysiloxane allows covalent attachment of quaternary ammonium sites to the membrane matrix and this enlarges the durability of the sensor.