CONFORMATIONAL INFORMATION FROM VIBRATIONAL-SPECTRA OF POLYANILINE

Vibrational (IR and Raman) spectra contain information about local con formations in materials. Their extraction, however, is possible only t hrough accurate modeling of tile vibrational spectra and by comparing various predicted spectra with experiment. We have established a Scale d Quantum Mechanical Oligomer Force Field for oligomers of leucoemeral dine base and for one oligomer of the imine form of polyaniline (perni graniline base). We conclude, that while the shorter oligomers of LB a re far from planarity, the longer oligomers and LB itself art: nearly planar. This result is confirmed by energy band structure calculations . There is no doubt, that an isolated LB polymer would energetically f avor a non-planar structure. Planarity is probably a consequence of in terchain interactions in the material. The vibrational analysis of the PNB form is not yet complete, but optical and energy band structure d ata suggest, that the samples contain the non-planar form.