Potentiometric sensors for Ag+ based on poly(3-octylthiophene) (POT) |
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Authors: | Mercedes Vázquez Johan Bobacka Ari Ivaska |
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Institution: | 1. Process Chemistry Centre, c/o Laboratory of Analytical Chemistry, ?bo Akademi University, 20500, ?bo-Turku, Finland 2. Graduate School of Materials Research (GSMR), ?bo Akademi University, ?bo-Turku, Finland
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Abstract: | Potentiometric ion sensors were prepared from the conjugated polymer poly(3-octylthiopene) (POT). The influence of additional
membrane components, including silver 7,8,9,10,11,12-hexabromocarborane (AgCB11H6Br6) and potassium tetrakis3,5-bis(trifluoromethyl)phenyl]borate (KTpFPB) as lipophilic salts, and 2.2.2]p,p,p-cyclophane as silver ionophore, was studied. The membrane components were dissolved in chloroform and membranes were prepared
by solution casting on glassy carbon disk electrodes. For comparison, POT-based potentiometric sensors were also prepared
by galvanostatic electrosynthesis of POT from the 3-octylthiophene monomer. All the POT-based ion sensors fabricated by solution
casting show Nernstian or slightly sub-Nernstian response to Ag+, even those based only on POT without any additional membrane components. The potentiometric response of electrochemically
polymerized POT depends on the film thickness and the doping anion incorporated in the conducting polymer during polymerization.
It is of particular importance that chemically synthesized undoped POT (without any additives) shows a sensitive and selective
potentiometric response to Ag+ ions although UV-vis results show that POT remains in its undoped form, i.e., POT is not oxidized by Ag+. This indicates that undoped POT can exhibit good sensitivity and selectivity to Ag+ also in the absence of metallic silver in the polymer film. In this case, the potentiometric response is related to interactions
between Ag+ and the conjugated polymer backbone.
Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, 13–16, 2005 |
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Keywords: | Ion-selective electrode Silver Poly(3-octylthiophene) Conducting polymer |
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