Vibrational Study of Short-Range Order and Structure of Polyaniline Bases and Salts

Abstract

Raman and infrared reflection spectra in the backbone deformations and lattice modes range (10−1000 cm -1 ) of EB/ES-I and EB/ES-II polyanilines are discussed and compared with those of an oligomer (BQBBa) and of the constitutive bricks of the polyaniline skeleton: diphenylamine (BB), N, N ‘-diphenyl-1,4-phenylenediamine (BBB), and N, N ‘-diphenyl-1,4-phenylenediimine (BQB). Short-range structure, scaling motif, and disorder are discussed. Emphasis is given to the relationship between hybridization, short-range structure, disorder, and optical properties. Ring, CH deformations, and librational/translational modes appear very sensitive to the static and dynamic disorder. Results show that vibrational spectroscopy allows to distinguish the two classes of polyaniline (ES-I and ES-II), whatever the inserted anion. The sketch of a continuous change of angle between the rigid virtual N−ring−N bond is proposed to describe the static orientational disorder.