Simple PVC–PPy electrode for pH measurement and titrations

Abstract

Cobaltabis(dicarbollide) [3,3'-Co(1,2-C2B9H11)](-)-doped polypyrrole (PPy) films have been prepared galvanostatically on glassy carbon electrodes in acetonitrile solution. The potential response behavior of the film of this new material has been investigated in some common pH buffers and in acid-base titrations. The potentiometric characteristics of the resulting films are indicative of a quasi-Nernstian response (approximately 50 mV/pH unit), a linearity range from pH 12 to 3 and correlation coefficients (r2) of approximately 0.98. The electrode is suitable for pH measurements and for monoprotic titrations of strong alkalis with strong acids, and weak bases with strong acids, but the long response time hinders the use of this electrode for multiprotic titrations. The time response has been dramatically improved by reducing the film thickness by using the template effect of a non-conducting polymer (PVC) cast over the graphite surface before PPy deposition. PPy polymerization occurs in the free channels of PVC leading to the formation of PPy wires. The morphological change of PPy does not affect the slope or linearity range. The response of the PVC-PPy electrochemical sensor is rapid and the sensor is easy to prepare, at low cost, and its performance is comparable with that of commercial glass electrodes.

All-solid-state hydrogen sensing microelectrodes based on novel PPy[3,3′-Co(1,2-C2B9H11)2] as a solid internal contact

“…However, with the use of the cobaltbis(dicarbollide) anions this exchange should be very low. But cobaltbis(dicarbollide)-doped PPy has been shown [32] to provide a cationic potentiometric response in ISE, indicating a (cationic) ion exchange process at the PPysolution interface. It would be expected that a similar ion exchange would occur at the PPy-PVC interface, thus providing a stable interface potential.…”

“…This microsensor is fabricated on needle shaped silicon probes [31], and is based on the use of a novel conducting polymer polypyrrole doped with anion [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ] − (See Fig. 1) [31][32][33] acting as the mediating layer between platinum and a poly(vinylchloride) (PVC) membrane incorporating the hydrogen selective ionophore tri-n-dodecylamine (TDDA).…”

Poly(3,4-ethylenedioxythiophene) doped with a non-extrudable metallacarborane anion electroactive during synthesis

“…On the other hand, the metallacarborane cobaltabisdicarbollide ([3,3 0 -Co(1,2-C 2 B 9 H 11 ) 2 ] K , 1 K -Scheme 1) has interesting features as a doping agent: a regular peanut shape, a weakly-coordinating ability, a large volume, a low charge density and hydrophobicity [10]. These electronic and structural characteristics have permitted to get polypyrrole materials in which the anion is non-extrudable [10][11][12][13][14][15], thence resulting in a substantial improvement of the overoxidation resistance [10,11], in selective cation-exchange properties [12], in sensors with a Nernstian response to pH [13,14] and in microcrystalline layers at the polymer surface [15]. Additionally, 1 K experiences a Co(IV)/Co(III) redox-state interconversion [16] at the experimental conditions of EDOT polymerization.…”

Novel all-solid-state copper(II) microelectrode based on a dithiomacrocycle as a neutral carrier

“…In that work, the conductive solid internal was graphite/epoxy [26]. In the present contribution, the membrane containing this novel ionophore is deposited on the conducting polymer (PPy[3,3 -Co(1,2-C 2 B 9 H 11 ) 2 ]) [27], itself deposited on the platinum microelectrodes. Optimal exper- imental conditions, selectivity over interferents, and sensing characteristics of a poly(vinyl chloride) matrix membrane are evaluated for potentiometric analysis toward Cu(II) ions.…”