Robert J. Mammone

Reduction Potentials: Key to Doping Phenomena In Polyacetylene, (Ch)X

Abstract When (CH)X is p-doped (oxidized) or n-doped (reduced) chemically or electrochemically the “dopant” ion may or may not be derived from the oxidizing or reducing agent as dictated by the nature of the specific doping reaction involved. The reduction potentials of neutral (CH)X and its various oxidized or reduced states have been determined electrochemically and have been used, together with known standard reduction potentials of a variety of redox couples, to rationalize the doping of (CH)X to the metallic regime by a number of dopant species, including gaseous O2 or benzoquinone (both in aqueous HBF4 solution), aqueous HClO4 and aqueous H2SO4. Reduction potentials can be used to predict new p- or n-dopants which are thermodynamically capable of doping (CH)X to the metallic regime. The p-doped polyacetylene is remarkably stable in the aqueous solutions in which it is synthesized.

The aqueous chemistry and electrochemistry of polyacetylene, (CH)x

Abstract Polyacetylene, (CH) x , is p-doped (oxidized) to the metallic regime by (i) gaseous oxygen in aqueous 48% (7.4M) HBF 4 , (ii) aqueous HClO 4 and H 2 SO 4 and (iii) electrochemical methods to give highly conducting materials that are remarkably stable in the aqueous solutions in which they are synthesized. The chemical doping reactions are consistent with the reduction potentials of polyacetylene in its various oxidation states and with the reduction potentials of the oxidizing agents. Polyacetylene can act as an electrocatalytic, ‘fuel-cell type’ electrode and also as an electrode-active cathode in rechargable battery cells in certain aqueous acid solutions.

Dielectric properties, vibrational and ESR spectra of electrochemically prepared poly(N-methylpyrrole) : effect of supporting electrolytes

Abstract Dielectric properties of electrochemically synthesized poly( N -methylpyrrole) (PNMP) prepared from aqueous electrolyte containing sulfate anions and aqueous electrolyte containing 4-hydroxybenzenesulfonate (HBS) anions have been obtained and compared with their ESR, Raman and grazing incidence FT-IR spectra. Dielectric and spectroscopic properties of PNMP were strongly dependent on the anion present in the supporting electrolyte during electrochemical polymerization. PNMP samples prepared from aqueous supporting electrolyte containing sulfate anions were highly insulating ( −9 S/cm) and had broad ESR linewidths while PNMP samples prepared from aqueous supporting electrolyte containing HBS anions were 10 5 times more conducting and had narrow ESR linewidths.

Gas plasma treatment of cathodes to improve cell performance

A porous carbon black or manganese dioxide cathode, or a lithium, magnesi calcium, zinc, or cadmium anode, is treated under vacuum with a gas plasma. The treated electrode is suitable for inclusion in a nonaqueous electrolyte cell and improves cell performance.

Stability and electrochemistry of polyacetylene in aqueous media

Abstract Preliminary studies have demonstrated that oxidized (‘p-doped’) polyacetylene, [CH +y (ClO 4 ) y − ] x , is relatively stable in a saturated aqueous solution (5.6 M) of Pb(ClO 4 ) 4 and that it can be reversibly oxidized and reduced electrochemically in this electrolyte. Novel rechargeable battery cells have been constructed using [CH +y (ClO 4 ) y − ] x as the cathode and lead as the anode in this medium. These batteries exhibits good coulombic efficiencies.

Use of gas plasmas to increase breakdown strengths in polycarbonate film/foil capacitors

It is shown that the electrical breakdown voltages of polycarbonate film/metal foil capacitors can be increased. This can be achieved by briefly exposing the metal foil in these spirally wound film foil sections to a low-pressure, low-temperature gas plasma. Exposure of tin/lead foil to a 96% CF/sub 4//4% O/sub 2/ gas plasma for four min, for example, produced >500% increase in breakdown voltage of sealed polycarbonate capacitors.<<ETX>>

Modification of the dielectric properties of parylene films by ion implantation

Abstract Dielectric properties of normally insulating Parylene C films were measured before and after chloride and argon ion irradiation. Bulk dielectric constants increased from 2.8 to approximately 15 - 20 after an ion flux of 10 16 Cl + or Ar + ions cm -2 . Bulk conductivity and dielectric losses also increased with ion irradiation.

Novel methods for preparing thin, high permittivity polymer dielectrics for capacitor applications

In order to create new materials which can be used as solid dielectric in high energy density capacitors, a number of insulating polymer films possessing very high dielectric constants and high breakdown strengths have been synthesized and/or modified by a variety of electrochemical and chemical techniques. The research goal was to increase effective bulk dielectric constants (and therefore capacitance) of thin, easily formed, flexible polymer films that could be used as solid dielectrics in wound capacitor designs. The physical and dielectric properties of each type of film are evaluated and compared.<<ETX>>

P-Doping of (CH)x to the Metallic Regime with Gaseous Oxygen. Application to Oxygen Fuel Cell Type Electrodes.

Trans-polyacetylene, (CH)x, can be p-doped (oxidized) to the metallic regime by gaseous oxygen in the presence of an aqueous solution of a non-oxidizing acid such as HBF4. The oxygen oxidizes the (CH)x to (CH(+y))x while the HBF4 supplies a stable fluoroborate counter anion to give a species such as (CH(+y)A(-y)x. The doping process is consistent with the reduction potentials of (CH)x and O2 in acid solution. In the absence of the acid, oxygen reacts irreversibly with the semiconducting (CH)x to destroy its conductivity.

Gas plasma treatment of cathodes to improve Li/SO{sub 2} cell performance

One rapid way to alter pendant groups on surfaces and/or to clean surfaces is to expose them briefly to low pressure, room, temperature gas plasmas. In this paper, the authors present results of using this simple vapor process to pretreat fabricated, porous carbon cathodes which were then assembled in spirally wound, hermetically sealed squat ``D`` sized Li/SO{sub 2} cells (PCI Model G-70). Overall cell performance such as start-up times, load voltage, and ampere-hour capacity were monitored before and after 28 days storage at 71 C. Performance during 3 A discharge at {minus}29 C was enhanced in cells containing plasma-treated cathodes. This treatment procedure should be of practical interest because fabricated carbon cathodes of any size can be quickly processed during normal manufacturing.