Showing papers by "Alan G. MacDiarmid published in 1984"

Optical studies of pyrolyzed polyacrylonitrile

Abstract: The results of measurements of the optical absorption spectra, IR absorption spectra, thermogravimetric analysis, and elementary analysis of pyrolyzed polyacrilonitrile are presented as a function of the pyrolysis temperature Tp and of the duration of pyrolysis. At Tp ∼ 200°C, an intermediate phase was discovered, containing conjugated CN sequences and a completely unreacted carbon backbone. The optical absorption data imply that the resulting polymer is a semiconductor with a delocalized π-electron system and an energy gap Eg ⋍ 2.5 eV. For Tp > 260°C, the weight loss rapidly increases, and the absorption edge gradually broadens and shifts to lower energies. The resulting polymer (after higher-temperature pyrolysis) contains CN and CCC conjugation sequences, but appears to be a complex structure consisting of a mixture of different chemical species.

A Rechargeable Battery Employing a Reduced Polyacetylene Anode and a Titanium Disulfide Cathode

Abstract: Novel rechargeable battery cells have been constructed using a reduced form of the conducting organic polymer, polyacetylene, as the anode, the inorganic intercalating material, titanium disulfide as the cathode, and either 1.0M LiCl0/sub 4/ in THF or 1.0M NaPF/sub 6/ in THF as the nonaqueous electrolyte. A feasibility study of the cells is described. It includes constant current discharge characteristics, stability, and rechargeability. The cells exhibited good stability and reversibility. Their performance was cathode limited, owing to the method used for fabricating the TiS/sub 2/ electrode.

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.

Electrochemistry of polyacetylene, (CH)x. Characteristics of the reduced polyacetylene electrode

Abstract: The coulombic efficiency, stability, constant-current discharge characteristics, energy density, power density and the relation of cell potential to degree of reduction of a partly reduced polyacetylene cathode, [Li+y(CHy–)]x(y⩽ 0.1), in a cell of the type [Li+y(CHy–)]x|LiClO4(tetrahydrofuran)|Li have been investigated. Coulombic efficiencies of ca. 100% are found at reduction levels up to 10 mol%. In its completely charged state the cell consists of parent, neutral (CH)x which appears to be stable indefinitely in the electrolyte. In the discharged state the [Li+y(CHy–)]x cathode also appears to be stable indefinitely in the electrolyte up to 7 mol% reduction, the highest level at which long-term stability studies have been carried out. Energy densities of ca. 201 W h kg–1(based on the weights of the electroactive materials involved in the discharge process) are obtained for 10 mol% reduced polyacetylene cathodes under constant-current discharge conditions. Maximum power densities of ca. 2900 W kg–1 are observed.

Optical anistropy of partially aligned polyacetylene film polymerized directly from gaseous acetylene

Abstract: Spectres d'absorption et de reflexion d'echantillons dopes ou non prepares par polymerisation de l'acetylene gazeux sur les faces cristallines de biphenyle contenant de l'amorceur de Shirakorwa dissous et/ou adsorbe

Polymer batteries and fuel cells having protic solvents and methods for their construction and use

Abstract: Secondary batteries are provided having at least one electrode which comprises a conjugated polymer having conjugated unsaturation along the main backbone chain thereof, said polymer being electrochemically oxidizable to a p-type doped material and electrochemically reducible to an n-type doped material. The battery is provided with an electrolyte which is protic in nature and which contains at least one ionic dopant capable of doping the polymerto a conductive state in the electrolyte.Methods of reversibly doping certain conjugated polymers in protic media are also disclosed. Fuel cells and electrolytic cells are also provided employing the protic doping systems and cells disclosed.