Infrared and Raman spectroscopy, when combined with normal mode analysis, provides a powerful tool for studying structure and morphology of macromolecules. Rigorous methods of analysis and their applications. The present proposal extends in several new directions. (1) The recent analysis of the longitudinal acoustic mode (LAM) of low-molecular-weight poly(ethylene oxide) will be extended to higher-molecular-weight samples, whose LAM spectra indicate the presence of complex folded-chain morphologies. (2) The recently refined comprehensive vibrational force field for multiply-chlorinated hydrocarbons. Will be used to analyze the conformational structure in chlorinated poly(vinyl chloride) and to determine the chain conformation of poly(vinylidene chloride). (3) Ab initio studies of force fields will be extended to two problems: the determination of the force field of hydrogen-bonded amide groups, and the development of molecular mechanics energy functions that, following their recently demonstrated mathematical transformation, permit the accurate reproduction of spectroscopic frequencies. These studies will advance their capabilities in using vibrational spectra to study structure in macromolecules, as well as enhance their understanding of specific polymeric systems.
