Specific heat and magnetic susceptibility of polyaniline nanotubes: inhomogeneous disorder

We report on the specific heat and magnetic susceptibility of polyaniline (PANI) nanotubes, which were self-assembled by a template-free method. It is interestingly found that an electronic specific heat is not observed from present data, and the lattice specific heat of PANI nanotubes can be interpreted in terms of the contributions from both the crystalline and the amorphous phases. The magnetic susceptibility includes a Pauli-like susceptibility and a Curie-type susceptibility. The results reveal an inhomogeneous disorder picture of PANI nanotubes (i.e., PANI nanotubes are composed of crystalline regions and amorphous regions). The crystallinity fraction Dg obtained from the specific heat is about 15% for the measured PANI nanotubes, which indicates that most of the polymer chains in the nanotubes are disordered.