Polyaniline-intercalated graphene oxide sheet and its transition to a nanotube through a self-curling process

This study reports the preparation of graphene oxide (GO)/polyaniline (PANI) nanotubes through polymerizing aniline monomers in the presence of GO sheets. Transmission electron microscopy (TEM) reveals that the obtained GO/PANI nanotubes have an outer diameter of ∼120 nm and an inner diameter of 15 nm. Fourier transform infrared (FT-IR) spectra and thermogravimetric analysis (TGA) curves verify the coexistence of GO and PANI in the produced nanotubes. X-ray diffraction patterns identify the intercalation of PANI chains between GO sheets. Specifically, SEM images reveal the formation of polyaniline-intercalated GO sheets in earlier stage. Subsequently, these initially-formed GO/PANI sheets would transform into nanotubes through a self-curling process. The changes of molecular structures and doping states of polyaniline molecules during the polymerization process are thought to be responsible for the self-curling behavior. Compared with the pristine PANI nanotubes, the GO/PANI nanotubes exhibit an even higher electrical conductivity and manifest their great potential in applications of various electrochemical devices.