Journal of Physical Chemistry B, Vol.108, No.18, 5564-5571, 2004
Spectroscopic characterization of doped poly(benzidine) and its nanocomposite with cationic clay
The resonance Raman spectroscopic characterization of doped poly(benzidine) and poly(benzidine)-clay nanocomposites is reported for the first time. The montmorillonite clay was used as a host structure to confine the polymer. The organic-inorganic hybrid materials were synthesized by oxidative polymerization of benzidinium ions intercalated in the host's nanospace. The formation of poly(benzidine) between the layers was confirmed by X-ray diffraction and scanning electron microscopy. The correlation between the Raman bands in the spectra of the free doped poly(benzidine) and those of the intercalated polymers indicates that the chain structures of free and intercalated polymers have the same chromophoric segments. The resonance Raman spectra of free and intercalated poly(benzidine) polymers show bands at 1140 and 1445 cm(-1) which indicate the presence of N=N bonding in the polymeric chains and also weak bands at 1400 and 1414 cm(-1) indicating that phenazine-like segments are formed in a lesser extension. The results are also confirmed by X-ray absorption spectroscopy at the N K-edge. The electrical conductivity of poly(benzidine) -clay nanocomposites is about 10(-4) S(.)cm(-1), which is of the same magnitude as that observed for free doped poly(benzidine). The EPR spectra of the nanocomposites show a low intensity signal.