X-ray irradiation: A non-conventional route for the synthesis of conducting polymers

A non-conventional methodology for polyaniline (PANI) synthesis using X-ray irradiation is presented in this article, and shows the oxidants normally used in the (chemical or electrochemical) conventional synthesis of PANI are not necessary. The method uses only high energy photons to interact with nitrate ions (NO3−) and aniline monomer in an aqueous solution. The polymerization mechanism has also been investigated using radical scavenger (DMSO), and the results suggest that the hydroxyl radical (OH) generated in situ during exposure to X-ray could be the main agent responsible for oxidation and subsequent polymerization of the aniline monomer. Characterization of the morphology of the polymer by scanning electron microscopy (SEM) reveals that the PANI obtained by X-ray presents a predominantly fibrillar morphology with an average fiber diameter of 90 nm. Additionally, thermogravimetric analysis (TGA), elemental analysis, gel permeation chromatography (GPC), conductivity measurements, and spectroscopic characterization in the UV-vis and IR regions, showed that the polymer obtained is the polyemeraldine salt (the conducting form of the polymer).