LANGMUIR-BLODGETT MANIPULATION OF ELECTRICALLY CONDUCTIVE POLYPYRROLES

Electrically conductive polypyrroles have been synthesized at the air–water interface of a Langmuir-Blodgett film balance by spreading mixtures of pyrrole monomer and a surface-active pyrrole derivative (3-octadecylpyrrole or 3-octadecanoylpyrrole) onto a subphase containing ferric chloride. The thickness and conductivity of the resultant polymers were found to depend strongly on the mole ratio of surface-active pyrrole to pyrrole monomer used in the dispersing solvent. It is possible to create films at the air–water interface ranging in thickness from monolayer to multilayer by varying this mole ratio and the type of surface-active pyrrole added to the spreading solution. The most highly conducting films (about 10−1 S/cm) were produced with mole ratios of pyrrole to surface-active pyrrole approaching 5000/1. Multilayers of these films were fabricated successfully by both the horizontal and vertical lifting methods. The conductivity of multilayers formed from the 3-octadecanoylpyrrole/pyrrole system was found to be highly anisotropic, with conductivities in the plane of the film about 107 times greater than conductivities across the film thickness. Superlattice films comprised of electrically conductive polypyrrole rich bilayers alternating with insulating bilayers of surface-active pyrrole molecules were also fabricated. © 1990, American Chemical Society. All rights reserved.