Conducting polymer photopolymerization mechanism: The role of nitrate ions (NO 3 −)

• Published in: Synthetic metals 2010, Vol.160 (1), p.61-64
• Main Authors: de Barros, R.A., Areias, M.C.C., de Azevedo, W.M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Conducting polymers; Exact sciences and technology; Forms of application and semi-finished materials; Photopolymerization; Physicochemistry of polymers; Polyaniline; Polymer industry, paints, wood; Polymerization; Polymers and radiations; Silver wire; Technology of polymers
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2009.09.033

This article presents a mechanism that explains the photopolymerization process of the aniline monomer in a medium that contains nitrate ions (NO 3 −). Polyaniline (PAni) and PAni/Ag 0 composite were prepared through the interaction of aniline nitrate, and AgNO 3 solution excited by UV light, respectively. In the first case, after UV interaction, the aniline monomer is polymerized while, in the second, PAni/Ag 0 composite is obtained. Contrary to what was expected, in the second case, the silver ions Ag + in the first stage of the process do not seem to be responsible for the polymerization mechanism. Instead, this article shows that the decomposition of NO 3 − by UV light generates hydroxyl radicals ( OH), which are responsible for polymerization of the aniline monomer. In the second stage, the silver ions can be reduced by oligomers produced during the photon polymerization process, which has a low oxidation potential compared to the aniline monomer, to yield the metal particle formation and consequently the metal/polymer composite.