Morphological control of self-assembly polyaniline micro/nano-structures using dichloroacetic acid

By simply changing the concentration of aniline ([An]) and the molar ratio of dichloroacetic acid (DCA) to aniline ([DCA]/[An]), the polyaniline (PANI) nanostructures with different morphologies including 1D-nanotubes, 2D-nanoflakes, 3D-nanofiber networks and microspheres were obtained through a self-assembly process, respectively. It was found that morphological changes were closely related to DCA used as reaction media and [DCA]/[An], and also affected by the pH and temperature of reaction system. The strong hydrogen bonding effect of the two chlorine groups and one carboxyl group of DCA with the amine/imine groups of aniline/polyaniline might be a driving force for the self-assembling nanostructures. Spectral study indicated that phenazine-like units could be obtained in the early reaction state under different [DCA]/[An] ratios, which could be responsible for the formation of nanofiber networks and microspheres at an acidic medium of pH < 1.