Influence of Thermal Treatment on Doped Polyaniline Studied by Resonance Raman Spectroscopy

• Published in: Macromolecules 2000-04, Vol.33 (8), p.3077-3083
• Main Authors: Pereira da Silva, J. E, de Faria, D. L. A, Córdoba de Torresi, S. I, Temperini, M. L. A
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Structure, morphology and analysis
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma990801q

Resonance Raman, ESR, and UV−vis−NIR techniques were used to characterize the secondary doping process in polyaniline (PANI). Experimental results obtained with the first two techniques showed the transformation of diamagnetic quinoid segments into radical semiquinone units while UV−vis−NIR experiments showed the increase of free carriers concentration due to extended conformation. Thermal effects on primarily and secondarily doped polyaniline were also studied by TGA, Raman, ESR, and UV−vis−NIR techniques. The appearance of new Raman bands with temperature was assigned to the formation of “phenazine-like” structures provoked by cross-linking. ESR and UV−vis−NIR experiments showed the absence of formation of addition radicalar structures due to thermal treatment in contrast to that observed after treatment with m-cresol.