Impedance spectroscopy and surface study of potassium-selective silicone rubber membranes

Peter D. van der Wal, Ernst J.R. Sudhölter, Bernard A. Boukamp, Henny J.M. Bouwmeester, David N. Reinhoudt

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Impedance spectroscopy measurements of silicone rubber membranes containing potassium-selective neutral carriers are reported. Two types of silicone rubbers are studied viz. the commercially available Siloprene and a novel copolymer, that was synthesized for application on Ion-Sensitive Field Effect Transistors (ISFETs). Three different potassium-selective ionophores have been studied, the natural ionophore, valinomycin, and two hemispherand type ionophores. One of the hemispherands can be covalently bonded to the polysiloxane copolymer matrix. The bulk resistance of the valinomycin containing membranes was found to be dependent on the contacting electrolyte solution. The K+/Na+ selectivity of the membrane is reflected in the behavior of the bulk resistance. The presence of a surface film on Siloprene membranes reported in the literature is confirmed. A surface study revealed the presence of small droplets exuded by the Siloprene membrane. The copolymer seems not to suffer from the presence of a surface film.
Original languageEnglish
Pages (from-to)153-168
Number of pages16
JournalJournal of electroanalytical chemistry and interfacial electrochemistry
Issue number1-2
Publication statusPublished - 1991

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