Characterization of the effects of varying the pH and monomer concentrations of poly(oxyphenylene) insulating films on carbon fiber electrodes

Abstract

By varying the conditions of an electrodeposition solution containing phenol and 2-allylphenol, thin poly(oxypheny1ene) films can be formed. These films have been used to insulate flame-etched carbon fiber electrodes to produce smaller electrode tip diameters. Experiments have been performed to test both the insulating properties and the film thickness of this poly(oxypheny1ene) copolymer at pH 5.0,7.0, and 9.0. The effects of monomer concentration on the polymer insulation integrity and film thickness have also been investigated. These experiments show that a decrease in pH results in thinner insulating films. It is also shown that monomer concentration can be decreased to 12mM phenoV18mM 2-allylphenol without causing an appreciable change in the insulating properties of the copolymer film; however, as the concentration is decreased, the pH appears to have less influence on the copolymer thickness.

Polyeugenol-Modified Platinum Electrode for Selective Detection of Dopamine in the Presence of Ascorbic Acid

“…In practice it is seldom observed, only if supporting electrolyte is strongly acidic 26 or if o-methoxyphenol is surface immobilized. 27 Possible mechanisms to account for the creation of the polymer matter on electrode surface may include the following: (i) a freeradical step-growth polymerization initiated by II as suggested for a mixture of phenol and 4-allylphenol leading to a poly-(oxyphenylene) film, 28 (ii) Diels-Alder reaction between o-quinone IV and allyl CdC bound giving a 1,4-benzenedioxane subunit, 29 (iii) dimerization of the radical II, 30 (iv) creation of lignan-like subunits by oxidative coupling of the substrate molecules, 30,31 and (v) hydroxylation of the o-quinone IV leading to the corresponding p-quinone. 27 Consequently, a poorly defined, highly cross-linked, compact structure is formed on the electrode surface, which hypothesized structure is shown in Figure 2.…”

Carbon Electrode Fabrication from Pyrolyzed Parylene C

“…1,9,10,11 Typically, to form small carbon electrodes, carbon fibers are etched and encapsulated in an insulating material such as glass or an electropolymerized layer. 3,8,12 In addition to this method, a number of alternative routes to prepare carbon electrodes have been developed. For instance, carbon coated pipettes have been prepared through chemical vapor deposition.…”

“…Encapsulated fibers and microfabricated structures are two of the most common methods utilized to form small-scale electrodes. Carbon microelectrodes find special utility for the measurement of biological species such as neurotransmitters. ,− Typically, to form small carbon electrodes, carbon fibers are etched and encapsulated in an insulating material such as glass or an electropolymerized layer. ,, In addition to this method, a number of alternative routes to prepare carbon electrodes have been developed. For instance, carbon coated pipets have been prepared through chemical vapor deposition. − An alternative route to form carbon electrodes is found in pyrolyzed photoresist films (PPFs). − When pyrolyzed in a reducing atmosphere, removal of heteroatoms from the photoresist structure and subsequent reduction of the film results in formation of a conductive carbon film.…”

Preparation of Tip-Protected Poly(oxyphenylene) Coated Carbon-Fiber Ultramicroelectrodes

“…Poly(oxyphenylene) electropolymerized coatings are frequently used as insulators due to the simplicity of the process in which oxidation of a methanolic solution of 2allylphenol forms a uniform insulting film over the exposed surface of the electrode [29 -31]. A subsequent heat curing step forms an adherent and highly resistive insulator [32,33].…”