Synthesis of graphene-like ultrathin polyaniline and its post-polymerization coating on nanosilica leading towards superhydrophobicity of composites

The present work reveals the formation of self-assembled graphene-like thin layered structure of electrochemically synthesized polyaniline (PAni) of thickness less than 4 nm. The nano-layered PAni sheets undergo transformation into squeezed macrorod-like structures which again gets unfolded upon ultrasonication into the sheet form. Such layered morphology provides possibility of post-polymerization coating of PAni on hydrophobic nanosilica via simple ultrasonication method when both are mixed together in the dispersion medium. Three different nanocomposites using polysulfone (PSU) as matrix were prepared by incorporating 8 wt% of PAni, nanosilica and PAni-coated nanosilica individually through solution mixing method. The hydrophobicity is found to increase for all three composites in comparison to pristine PSU. However the synergistic improvement in hydrophobicity was observed for PSU/PAni-coated nanosilica composite. The hydrophobicity measured in terms of the contact angle against water was found to be 161 degrees, 137.7 degrees and 85.9 degrees by the composites PSU/PAni-coated nanosilica, PSU/nanosilica and PSU/PAni respectively. Coating of PAni gets partially detached from nanosilica during the preparation of composite which partly covers the surface with tiny wrinkles leading to the synergistic improvement towards superhydrophobicity. (C) 2016 Elsevier B.V. All rights reserved.