Spectroscopic investigation of conjugated polymers derived from nitroanilines.
For the first time, the resonance Raman spectroscopy was used to characterize polymers derived from meta- and para-nitroanilines. In order to improve the polymer structure analysis, other techniques were also used such as FTIR, UV-vis, XRD, XPS, EPR and N K-XANES. The insertion of strong electron-withdrawing groups (NO2) in polyaniline (PANI)-like backbone causes drastic changes in the lower energy charge transfer states, related to the polymer effective conjugation length. The resonance Raman data show that the NO2 moiety has a minor contribution on the CT state in poly(meta-nitroaniline), PMN, while in the poly(para-nitroaniline), PPN, the quinoid structure induced by para-substitution increases the charge density of NO2 groups, causing a more localized chromophore. The characterization of the imine nitrogen and of the protonated segments was done by XPS, N K-XANES and EPR spectroscopies and the lower polymerization degree of PPN, in comparison to PMN, is confirmed by XRD and TG data.
Ando
Rômulo A
RA
Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077 São Paulo, SP, Brazil.
do Nascimento
Gustavo M
GM
Landers
Richard
R
Santos
Paulo S
PS
D000814:Aniline Compounds / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods*; D014961:X-Ray Diffraction
D000814:Aniline Compounds; D011108:Polymers; C008625:nitroaniline