Polyacrylonitrile (PAN) films have been fabricated by both spin and solvent casting techniques, and pyrolyzed to produce carbon films in the thickness range of 200-50000 A. These films have higher electrical conductivities than carbon films produced from most other precursors at similar temperatures. The chemical structure of the films at different stages of processing was investigated by UV, IR, Raman, and XPS spectroscopies. An extra degree of control over the final electrical conductivity was obtained by varying the PAN content of copolymer precursors. Oxidation rates and an activation energy were determined. Finally, processing techniques are described which allow both dry and wet film transfer and lithographic patterning.

Novel ultrathin (0.4 pm) porous carbon fdms are employed as transducers for amperometric biosensors. Such foamlike nanoscopic films couple the advantages of high enzyme loadings (within the micropore hosts) and large microscopic area with a small geometric area. Both electropolymerization and metalization are used to entrap the enzyme within the micropores. Scanning electron microscopy sheds useful insights into the unique morphology of the growing enzyme layer. The greatly enhanced sensitivity is coupled with a fast and stable response. Factors influencing the performance of porous-filmbased biosensors are examined and discussed. The improved performance is illustrated in connection with glucose and p b e d sensors. The latter offers a remarkably low detection limit of 2.5 X 10-8 M. The new nanoscopic foams should prove useful for many other electroanalytical applications. National Laboratories? overcome this limitation as they combine the high surface area of porous electrodes with a 0.1-1.0pmfilm thickness. Inde4,onecanviewthesefoamlike 0003-2700184103661 988504.50lo Abstract published in Advance ACS Abstracts, May 15, 1994.

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Polyacrylonitrile films have been spin cast and pyrolyzed to produce thin (500–1500 Å) carbon films. These films have higher electrical conductivities than films produced by other methods at similar temperatures. The conductivity can be varied by at least four orders of magnitude by changing the pyrolysis temperature. Ultraviolet, infrared, and Raman spectroscopies were used to investigate the chemical structure of the films during different stages of processing.

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We describe the fabrication and characterization of new nanoband electrodes, based on ultrathin carbon films produced by carbonization of deposited polyacrylonitrile. Because of their controlled thickness (down to molecular dimensions) and high electrical conductivitv, such electrodes show great promise for electroanalytical work. Sigmoidal voltammograms, characteristic of nonlinear diffusion, are obtained. Direct measurements in electrolyte-free organic media are illustrated. Effects of band thickness, scan rate, solute and electrolyte concentrations, and other variables are explored. These films and other forms of carbon from polyacrylonitrile present opportunities for a wide range of electrode materials.