Enhanced Lifetime and Adhesion of K+‐,  NH 4  + ‐, and Ca2+‐Sensitive Membranes on Solid Surfaces Using Hydroxyl‐Modified Polyvinylchloride Matrices

Abstract

Liquid-liquid junction membranes prepared from a modified polyvinylchloride (PVC) polymer with 0.6 weight percent (w/o) OH introduced, (PVC-OH) and 0.25 w/o SIC14 added during casting have substantially enhanced adhesion on glass or Si compared to PVC-based membranes. Ion-selective electrodes for NH4 + based on a dioctyladipate/nonactin ion exchanger show enhanced adhesion, as do Ca 2 § membranes using a neutral ion carrier/o-nitrophenyloctylether mixture. Enhanced surface adhesion is demonstrated to result in improved lifetime for K § membranes coated on n-Si electrodes and on ion-sensitive field effect transistors (ISFET's). Electron micrographs show large differences in surface quality for PVC vs. PVC-OH/SiC14-based membranes after aqueous storage.Integrated potentiometric sensors such as the ion-sensitive field effect transistor (ISFET) utilize ion-selective electrode (ISE) technology to produce membrane-coated devices specific to a variety of ions (1). However, the typical polyvinylchloride (PVC) liquid-liquid junction-based membranes used with an ISE are not ideally suited to application to solid-state devices. Problems with membrane lifetime due to leaching of material from the membrane (2) and poor adhesion (3)to the sensor arise. Recently, we reported on a K+-sensitive ISE membrane, based on a chemically modified form of PVC, that exhibits enhanced adhesion on solid surfaces with minimal changes in electrochemical properties (4). Formation of a covalent bond between PVC and a solid surface is accomplished via synthesis of the hydroxyl-substituted derivative, PVC-OH (0.6 weight percent [w/o] OH) and reaction with SIC14 according to Scheme I. In this paper we demonstrate that the ~c,-I ~8i-.o. -o-/-o-..l ~ o,

Characterization of All Solid State Hydrogen Ion Selective Electrode Based on PVC-SR Hybrid Membranes

“…Leaching out of the active component and the plasticizer from the polymeric matrix causes the deterioration of the response of the electrodes and leads to limited electrode life time [7][8][9]. Up to date, several approaches were made to solve this problem including chemical anchoring of PVC membranes containing OH groups to an oxide surface [10,11], mechanical attachment of the membrane [12], photocuring techniques [13,14], and several other polymer materials [15][16][17][18][19]. Among them, SR based membranes were formulated without a plasticizer (which is owing to their low glass transition temperature), because it adhere strongly to most solid surfaces and exhibit less interference from lipophilic anions present in biological fluids.…”

Selenite-Selective Membrane Electrodes Based on Ion Exchangers and Application to Anodic Slime

“…Among these Ca 2+ , K + and NO3 -ion electrodes are commercially available. [1][2][3] The first liquid ion exchanger membrane electrode was prepared by Ross in 1967 4 using phosphate esters as the active material. This electrode was used for the determination of calcium in blood serum.…”

An all-solid-state reference electrode based on the layer-by-layer polymer coating

“…SiCl 4 -doped polyurethane-based membranes exhibited much better adhesion and stability, and a much longer lifetime. 17,[20][21][22] Recently, we have shown that the addition of SiCl 4 to TPU-based matrices enhances the potentiometric response and stability, due to the chemical bonding between Si and CLO in urethane groups, in which the cross-linking was confirmed by DSC, FT-IR, and XPS experiments. 23 Thus, the stabilities of the SSREs using PUMs with and without SiCl 4 were tested by dipping them in a 1.0 M KCl solution at room temperature for two weeks.…”