Cylindrical Self-Assembly and Flow Alignment of Comb-Shaped Supramolecules of Electrically Conducting Polyaniline

Electrically conducting hexagonally self-assembled nanostructures of poly(aniline) (PANI) protonated with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and hydrogen bonded with resorcinol (res), 4-ethylresorcinol (C2res) or 4-hexylresorcinol (C6res) are studied. Small-angle X-ray scattering (SAXS) of PANI(AMPSA)0.5(Cnres)y with y ) 0, ..., 1.5 indicate cylindrical self-assembly in all cases, and the long period depends on n and y. Addition of Cnres leads to plasticization and an increase of conductivity of up to ca. 4 orders of magnitude until saturation is achieved upon approaching y ) 1. Simultaneously, the temperature gradient of the conductivity dσ/dT near the room temperature changes from positive to negative, which is reminescent to a transition from a thermally activated hopping-type to a more “metallic-like” behavior. It is suggested that, upon complexation with especially res and C2res, the PANI chains become progressively more confined in cylinders suggesting their stretching. Overall alignment of the local self-assembled domains was also aimed. In films, anisotropic overall structure and conductivity are observed upon pressing the “melt” samples between two glass plates. In more bulky samples, so far, large amplitude oscillating shear flow leads to biaxial structural anisotropy without observable conductivity anisotropy, potentially indicating the importance of residual defects for the transport properties.