Electrical Properties of Polypyrrole-Poly(ether urethane) Composite Films

Polypyrrole (PPy)-poly(ether urethane) (PEU) composite films were prepared via the chemical polymerisation of pyrrole in a tetrahydrofuran solution of PEU containing copper(II) chloride and lithium perchlorate, and subsequent casting. The electrical conductivity of the composite film (weight ratio of pyrrole to PEU 1:1, [CuCl₂] 0.1 mol/mol pyrrole, [LiClO₄] 1.0 mmol/g PEU) in the direction parallel to the film surface was 0.16 S/cm, which was considerably higher than the conductivity in the direction perpendicular to the film surface (8.0 x 10'⁷ S/cm). The low conductivity in the perpendicular direction is attributed to the ionic conduction of the PEU-lithium perchlorate component, with little contribution from the electronic conduction of the PPy component. From the SEM micrographs of the composite film, it appeared that the PPy layer was formed at the air side of the film.