Low-temperature heat capacities of polyaniline and polyaniline polymethylmethacrylate blends

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 (gamma) prevails in all samples. The value of gamma for polyaniline is 14 mJ/mol 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. [S0163-1829(98)51448-8].