Spectroscopic Study on the Structural Differences of Thermally Induced Cross-Linking Segments in Emeraldine Salt and Base Forms of Polyaniline
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
01/11/2013
01/11/2013
2012
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Resumo |
This paper reports the spectroscopic study on the structural differences of thermally induced cross-linking segments in polyaniline in its emeraldine salt (PANI-ES) and base (PANI-EB) forms. Casting films of PANI-ES (ES-film) and PANI-EB (EB-film) were prepared and heated at 150 degrees C under atmospheric air for 30 min. Raman spectra excited at 632.8 nm of heated ES-film presented the characteristic bands of phenazine-like structures at 1638, 1392, and 575 cm(-1), whereas EB-film showed lower relative intensities for these bands. The lower content of phenazine-like segments in heated EB-film is related to residual polaronic segments from preparation procedures, as revealed by Raman. This statement was confirmed by a sequence of thermal and doping experiments in both films. Quantum-chemical calculations by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) showed that the phenazine-like structure presents the intense Raman band at 1350 cm(-1) due to heterocycle breathing mode, and the non-phenazine-like structure (substituted hydrophenazine-type) presents higher energy for HOMO-LUMO transition, indicating the lack of conjugation in the heterocycle compared with the phenazine-like structure. According to experimental and theoretical data reported here, it is proposed that only thermally treated PANI-ES presents phenazine-like rings, whereas PANI-EB presents heterocyclic non-aromatic structures. CNPq CNPq FAPESP FAPESP |
Identificador |
JOURNAL OF PHYSICAL CHEMISTRY B, WASHINGTON, v. 116, n. 48, pp. 14191-14200, DEC 6, 2012 1520-6106 http://www.producao.usp.br/handle/BDPI/37619 10.1021/jp309484e |
Idioma(s) |
eng |
Publicador |
AMER CHEMICAL SOC WASHINGTON |
Relação |
JOURNAL OF PHYSICAL CHEMISTRY B |
Direitos |
closedAccess Copyright AMER CHEMICAL SOC |
Palavras-Chave | #RESONANCE RAMAN-SPECTROSCOPY #CHEMICAL OXIDATIVE POLYMERIZATION #BY-LAYER MANIPULATION #SYNTHESIZED POLYANILINE #VIBRATIONAL-SPECTRA #CONDUCTING POLYMERS #MECHANICAL-PROPERTIES #CONJUGATED POLYMERS #AB-INITIO #FILMS #CHEMISTRY, PHYSICAL |
Tipo |
article original article publishedVersion |