Electrical charge transport in polypyrrole/sulfated poly(beta-hydroxyethers) blends

Electrical properties of polypyrrole/sulfated poly(beta -hydroxyethers) (PP y/sulfated PHE), wherein the sulfated hydroxy groups in the latter componen t worked as dopants, were investigated, varying the doping level as well as the PHE molecular mass (M-n). The blends can be categorized into three gro ups: the slight-, moderate- and high-sulfation. In the moderate-sulfation, the charge transport above 80 K is characterized by the two-dimensional var iable-range hopping (2D-VRH) through the PPSI conducting channels formed on the surfaces of coiled PHE. In the high-sulfation, the dimensionality of t he VRH changes from two to three. In addition, the carriers in the metallic states also participate in the charge transport. In the slight-sulfation, the hopping to the nearest neighbors operates in addition to the 2D-VRH. Fo r all the samples, the dominant conduction below 80 K is the hopping govern ed by a Coulomb gap due to the electrostatic interaction between carriers. The change in the doping level causes the transition from one sulfation gro up to another when M-n is large, whereas most blends are categorized into t he moderate sulfation group when M-n is small. This behavior is interpreted , considering the M-n dependence of the spatial distributions of the PPSI i n the PPy/PHE blends. (C) 2000 Elsevier Science Ltd. All rights reserved.