Vibrational Properties of PolyanilineIsotope Effects

Abstract

The effect of polyaniline deuteration on the Raman spectra of this polymer has been studied in detail. Four types of samples have been prepared: nondeuterated polyaniline, polyaniline deuterated selectively on the ring, polyaniline deuterated selectively on nitrogen, and polyaniline deuterated both on the ring and on the nitrogen. Selective deuteration allowed for experimental verification of the Raman modes assignment proposed for different types of polyaniline. In particular, the contribution of C−H bending to C−C stretchings in benzoid and quinoid rings of the polyaniline chain has been confirmed. In addition, selective deuteration enabled us to identify, for the first time in polyaniline, the band associated with N−H bending deformations. Raman spectroelectrochemical investigations of the four above-mentioned types of polyaniline samples gave evidence that in protonated polyemeraldine two types of structures coexist, namely, semiquinone radical cation (polaronic lattice) and quinoid dication (bipolaronic). The vibrations of the former are in resonance with the energy of the blue (457.9 nm) excitation line, whereas the vibrations of the latter undergo resonance enhancement if the red (676.4 nm) line is used. The calculated and experimentally observed Raman modes for both polaronic and bipolaron structures are in very good agreement in all four cases of differently deuterated polyaniline.

Nanocompósitos eletroativos de poli-o-metoxianilina e polissacarídeos naturais

“…Alguns picos Raman característicos da POMA-ES são: 577 cm -1 atribuído à deformação da amina no plano, 1356 cm -1 atribuído ao cátion radical (estiramento C-N + ) e 1597 cm -1 atribuído ao estiramento C-C do anel benzeno. A Tabela 1 traz os picos Raman da base e do sal de POMA esmeraldina, e suas respectivas atribuições, as quais são "atribuições tentativas" baseadas nas referências [30][31][32][33][34][35] que se referem à PANi.…”

Molecular Structure, Vibrational Assignments and Non-Linear Optical Properties of 4,4’ Dimethylaminocyanobiphenyl (DMACB) by DFT and <i>ab Initio</i> HF Calculations

“…For the title compound the υ CN mode is observed at 1203 cm . The out-of-plane CH deformation bands ω CH are expected in the range 740 -990 cm −1 [21]. As seen from Table 3, the DFT-B3LYP calculation give wave numbers at 863,829 cm −1 .…”

“…The absorption appears at higher frequencies than the corresponding absorption of aliphatic amines because the force constant of the C-N bond is increased by resonance with the ring. Louran et al [21] reported a value at 1220 cm −1 for υ CN for polyaniline. For the title compound the υ CN mode is observed at 1203 cm .…”

Síntese e caracterização de hidro-esponjas de polímeros condutores

“…Observa-se na Figura 58 que os nanotubos formados apresentam estrutura morfológica bem mais definida sem a presença de uma grande quantidade de estruturas granulares entre os mesmos. [199][200][201][202].…”

“…A banda localizada na região entre 1510-1480 cm -1 é muito importante na caracterização da estrutura polimérica da PANI, uma vez que esta região está associada aos dois tipos de portadores de carga da PANI, polarons e bipolarons, podendo indicar a população relativa entre os mesmos [200,201,203]. Uma análise detalhada desta importante região do espectro tem sido reportada para materiais híbridos de PANI/hexaniobato e tem mostrado que as populações relativas polarons/bipolarons são sensíveis à interação entre cadeia polimérica e a alta acidez da superfície do hexaniobato [204][205].…”