Polyaniline intercalated vanadium pentoxide nanosheets for the improvement of lubricity of base oil

Abstract

Vanadium pentoxide (V2O5) nanosheets were prepared and tested as an additive to improve the wear/friction-reducing and load-carrying properties of the base lube, paraffin oil. For further advancement of these properties, in situ intercalation of polyaniline (PANI) was achieved hydrothermally using the starting materials as V2O5 powder and aniline. During the process, V2O5 powder was exfoliated into nanosheets, and aniline was oxidatively polymerized under acidic conditions producing polyaniline, which intercalated between the nanosheets to yield the composite PANI-V2O5.nH2O (PVO). Separately synthesized PANI, exfoliated V2O5 nanosheets, and the in situ synthesized composite were characterized by p-XRD, HR-SEM, TEM, FTIR, and XPS. Intercalated PANI prevented restacking of nanosheets and reduced their agglomerating tendencies. A significant increase of interplanar spacing corresponding to the (001) plane of V2O5 in the nanocomposite confirms considerable interaction between the nanosheets and PANI. Although there is no chemical interaction, the non-covalent interactions like hydrogen bonding between the organic and the inorganic components through NH(PANI)...... O-V(V2O5) and van der Waals forces hold the structure firmly. Tribological tests performed on a four-ball tester following ASTM D4172 and ASTM D5183 standards in paraffin oil revealed significant enhancement in friction/wear-reducing and load-carrying properties of the composite compared to V2O5 nanosheets and PANI. The advanced activity of the nanocomposite validates synergy between PANI and V2O5 nanosheets. The morphological studies of the worn surface by SEM and AFM studies endorsed the observed results. The EDX and XPS studies of the tribofilm confirmed the elemental composition and chemical states of all the elements, respectively. A possible mechanism of lubrication has been presented.