Photolithographic synthesis of polyaniline nanofibres

Abstract

Thin films of polyaniline nanofibres were synthesized using ultraviolet irradiation of aqueous solutions of aniline, nitric acid, and ammonium peroxydisulfate. The parent solution was spin coated on a planar substrate, and allowed to polymerize in the dark for 4–5 min. The substrate was then exposed to ultraviolet light for 6–10 min. Irradiation was carried out either with a frequency-tripled Nd:YAG laser, or with a mercury vapour lamp. The polyaniline fibres and films were characterized with scanning and transmission electron microscopy, and with Fourier transform infrared spectroscopy. Fibres had typical diameters between 20 and 150 nm, and lengths of the order of microns. Bulk polyaniline formed in the unirradiated portion of the samples. Using a masking technique, alternating stripes of bulk polyaniline and polyaniline nanofibres were produced.