Low-temperature heat capacities of polyaniline and polyaniline polymethylmethacrylate blends

Abstract

Heat-capacity measurements between 0.4 and 10 K have been made on doped polyaniline and its blends with polymethylmethacrylate. At lower temperatures, a finite electronic term (\ensuremath{\gamma}) prevails in all samples. The value of \ensuremath{\gamma} for polyaniline is 14 mJ/mol ${\mathrm{K}}^{2}$, but higher by a factor of about 6 for the blends. Using the free-electron model, the corresponding density of states at the Fermi level $[{N(E}_{F})]$ are calculated and compared with that obtained from magnetic susceptibility measurements on the same samples. It is shown that caution must be used in determining ${N(E}_{F})$ from magnetic susceptibility measurements in polyaniline and other less conducting polymeric materials.