Aleksandra Janošević

Carbonised polyaniline and polypyrrole: towards advanced nitrogen-containing carbon materials

Polyaniline (PANI) and polypyrrole (PPY) undergo carbonisation in an inert/reduction atmosphere and vacuum, yielding different nitrogen-containing carbon materials. This contribution reviews various procedures for the carbonisation of PANI and PPY precursors, and the characteristics of obtained carbonised PANI (C-PANI) and carbonised PPY (C-PPY). Special attention is paid to the role of synthetic procedures in tailoring the formation of C-PANI and C-PPY nanostructures and nanocomposites. The review considers the importance of scanning and transmission electron microscopies, XPS, FTIR, Raman, NMR, and EPR spectroscopies, electrical conductivity and adsorption/desorption measurements, XRD, and elemental analyses in the characterisation of C-PANIs and C-PPYs. The application of C-PANI and C-PPY in various fields of modern technology is also reviewed.

Synthesis and characterization of conducting polyaniline 5-sulfosalicylate nanotubes

Conducting polyaniline 5-sulfosalicylate nanotubes and nanorods were synthesized by the template-free oxidative polymerization of aniline in aqueous solution of 5-sulfosalicylic acid, using ammonium peroxydisulfate as an oxidant. The effect of the molar ratio of 5-sulfosalicylic acid to aniline on the molecular structure, molecular weight distribution, morphology, and conductivity of polyaniline 5-sulfosalicylate was investigated. The nanotubes, which have a typical outer diameter of 100-250 nm, with an inner diameter of 10-60 nm, and a length extending from 0.4 to 1.5 microm, and the nanorods, with a diameter of 80-110 nm and a length of 0.5-0.7 microm, were observed by scanning and transmission electron microscopies. The presence of branched structures and phenazine units besides the ordinary polyaniline structural features was revealed by infrared and Raman spectroscopies. The stacking of low-molecular-weight substituted phenazines appears to play a major role in the formation of polyaniline nanorods. The precipitation-dissolution of oligoaniline templates as a key element in the formation of polyaniline nanotubes is proposed to explain the crucial influence of the initial pH of the reaction mixture and its decrease during the course of polymerization.

Chemical oxidative polymerization of dianilinium 5-sulfosalicylate

Dianilinium 5-sulfosalicylate was prepared in situ and then oxidized in aqueous solution with ammonium peroxydisulfate. The precipitated polyaniline 5-sulfosalicylate was soluble in polar aprotic solvents and showed conductivity of ∼0.1 S cm−1. Scanning electron microscopy revealed the coexistence of nanorods and granular morphology of the polyaniline 5-sulfosalicylate. The weight-average molecular weight and poly-dispersity index were determined by gel-permeation chromatography as 53000 and 9.0, respectively. FTIR spectroscopic analysis combined with AM1 and MNDO-PM3 semi-empirical quantum chemical studies of the polymerization mechanism indicate both covalent and ionic bonding of sulfosalicylate to polyaniline chains. Raman spectroscopy proved the presence of substituted phenazine structural units besides ordinary emeraldine segments.