Study of the effect of acid doping on the properties of poly( N-seleno- p-phenylene diamine)

Abstract

Poly( N-seleno- p-phenylene diamine), before and after doping, has been studied by infrared absorption. X-ray electron spectroscopy (XPS), electron spin resonance (ESR) and room temperature conductivity measurements. The dopants used were inorganic (HCl, H 2SO 4) and organic (CF 3COOH, CH 3SO 3H, CH 3OOH) acids. It is shown by IR absorption that only the CH 3COOH doping does not systematically destroy the C-N and/or the N-Se-N bonds. The XPS analysis shows that some oxygen is present in the polymer even before doping. This oxidation and the dissymmetry of the monomer can justify the presence of an ESR signal before doping. After doping with CH 3COOH the increase in the ESR signal and conductivity can be attributed to polymer protonation. This is in good agreement with the new component of the N1s signal obtained by XPS which can be attributed to N + radicals. However, it is shown by XPS that when the CH 3COOH concentration increases, the N-Se-N bonds are partly destroyed which can explain the decrease in the ESR signal and the conductivity.