Self-assembly of aniline oligomers

A great number of nano/microscaled morphologies have recently been prepared during the oxidation of aniline. At the early stage of oxidation, aniline oligomers are obtained, often in spectacular morphologies depending on reaction conditions. Herein, the flower-like hierarchical architectures assembled from aniline oligomers by a template-free method are reported. Their formation process is ascribed to the self-assembly of oligoanilines through non-covalent interactions, such as hydrogen bonding, hydrophobic forces, and π-π stacking. The model of directional growth is offered to explain the formation of petal-like objects and, subsequently, flowers. In order to investigate the chemical structure of the oligomers, a series of characterizations have been carried out, such as matrix-assisted laser desorption ionization, time-of-flight mass spectrometry, gas chromatography coupled with mass spectrometry analysis, X-ray diffraction, and UV/Vis, Fourier-transform infrared, and Raman spectroscopies. Based on the results of characterization methods, a formation mechanism for aniline oligomers and their self-assembly is proposed.