Metal-insulator molecular multilayers of electroactive polymers: Intercalation of polyaniline in mica-type layered silicates

Highly oriented multilayered films of polyaniline are fabricated by intercalative polymerization of aniline in fluorohectorite, a synthetic mica-type silicate. The insulating hybrid becomes electrically conductive when exposed to HCl vapors with an in-plane conductivity of 0.05 S cm−1. The conductivity of the multilayered films is highly anisotropic with the in-plane conductivity 105 times higher than the conductivity in the direction perpendicular to the film. Electrical conduction is rationalized in terms of a granular metal below the percolation threshold. Phonon-assisted and field-assisted tunneling between localized states is the predominant mechanism at room and lower than 200 K temperatures respectively. The lower conductivities are attributed to an increased localization of charge carriers in the polymer.