Multifunctional polyaniline hybrid nanofiber with YVO4 (Er2%;Yb8%)

Abstract

We synthesized electrospun nanofibers based on polyaniline (PAni) and orthovanadate from Yttrium co-doped with Erbium and Ytterbium [YVO4 (Er2%, Yb8%)]. We evaluated the association of the electrical and thermal properties of PAni with the upconversion (UC) effect due to the orthovanadate. We characterized the material by UV–Vis Spectroscopy, Fourier transform infrared (FTIR), Impedance Spectroscopy and Photoluminescence. Initially, we obtained polyaniline by emulsion polymerization in presence of surfactant, sodium dodecyl sulfate, yttrium orthovanadate and polyvinyl alcohol, resulting in a homogeneous dark green color solution. When we subjected the solution to a 14 kV constant electric potential difference applied between a 12 mm diameter needle (cathode) and a collecting plate (anode) 12 cm apart, the material deposited in the form of fibers. SEM results show that these fibers presented an average diameter of (89 ± 40) nm. On the other hand, when excited with radiation of wavelength λ = 980 nm (2.5 W) the material emitted radiation in the visible region with characteristic peaks at 525, 543 and 553 nm. The emission of intense green light is characteristic of UC effect. Due to photothermal characteristic of PAni the sample was heated, reaching temperatures close to 100 °C without suffering degradation. Measurements of photoluminescence showed that when exposed to HCl vapor, the material presented an increase of almost 100% in the intensity of light emitted in the UC effect, as well as a reduction of its electrical impedance from the order of GΩ to 900 KΩ, in a reversible process. These results are suggestive that these composite fibers appear as a promising active material for the sensing of acid vapors.