Electrical conductivity of hollow polyaniline microspheres synthesized by a self-assembly method

In this letter, we report the electrical properties of hollow polyaniline (PANI) microspheres. beta-naphthalene sulfonic acid (NSA) and salicylic acid (SA) doped PANI microspheres were synthesized by a self-assembly method. The room-temperature conductivity is 8.6x10(-2) S/cm for PANI-NSA microspheres (0.8-2 mum in outer diameter) and 5.6x10(-4) S/cm for PANI-SA microspheres (3-7 mum in outer diameter). The conductivity of an individual PANI-SA microsphere is measured directly by a two-probe technique, about 8x10(-2) S/cm (which is two orders of magnitude higher than that of a PANI-SA microsphere's pellet). The measurements of conductivity, I-V curve, and magnetoresistance demonstrate that the electrical properties of PANI microspheres are dominated by the intersphere contacts due to the sample's microscopic inhomogeneity. (C) 2004 American Institute of Physics.