Low-temperature resistivities of nanotubular polyaniline doped with H3PO4 and β-naphthalene sulfonic acid

The temperature dependence of the resistivity of nanotubular polyaniline (PANI) doped with H3PO4 and beta-naphthalene sulfonic acid (NSA) synthesized by a "template-free method" has been investigated. The molar ratios of H3PO4 (NSA) to aniline monomer (represented by H3PO4 /An and NSA/An) of the samples are H3PO4 /An=0.01, 0.05, 0.3, 0.5 and NSA/An= 1, 2, respectively. It is found that 1n rho(T) is linear in T-1/2 and the resistivity is sensitive to the doping concentration. For NSA/An= 1 sample, a crossover at,57 K in the plot of 1nrho(T)similar toT(-1/2) has been observed. On the basis of detailed analysis of the structure characteristics of the PANI nanotubes, we suggest a hopping-tunneling model to explain the experimental results. (C) 2003 American Institute of Physics.