Ion sensors using one-component room temperature vulcanized silicone rubber matrices

Two different types of one-component room temperature vulcanized (RTV) sili cone rubbers (Dow Coming 3140 and 730 RTV) are further examined as alternat ives to PVC for formulating ion-selective membranes. The four different ion ophores used in this work are: valinomycin (K+), ETH 1001 (Ca2+), tridodecy lamine (H+) and trifluoroacetyl-p-decylbenzene (CO32-). Ion-selective RTV m embranes are made by incorporating an ionophore along with a plasticizer an d/or an ionic additive (i.e, either plasticized or non-plasticized). In mos t cases, potentiometric ion responses and selectivities of RTV-based membra nes, when formulated properly, compare favorably to those of corresponding PVC-based membranes. In general, 730 RTV is found to be better suited for f ormulating plasticizer-free membranes. The preferred matrices are a plastic ized 3140 RTV for Ca2+ and a non-plasticized 730 RTV for CO32-. Planar soli d-state sensors fabricated with selected RTV membrane formulations are show n to function well with a stable response signal and an extended sensor lif etime. (C) 1999 Elsevier Science S.A. All rights reserved.