NORMAL COORDINATE ANALYSIS OF INFRARED AND RAMAN-SPECTRA OF SYNDIOTACTIC POLY(METHYL METHACRYLATE)

Infrared and Raman spectra of crystalline syndiotactic poly(methyl methacrylate) have been analyzed by normal coordinate calculations, using a combined valence force field transferred from branched hydrocarbons and from methyl acetate. Calculations have been done for a single chain all-trans backbone structure of syndiotactic poly(methyl methacrylate) with parallel and antiparallel side-group orientations. The infrared and Raman bands observed can be satisfactorily interpreted on the basis of the calculated potential energy distributions. The best agreement between the calculated and experimental spectra has been found for the alternate cis and trans mutual orientations of the C = O and C-CH3 bonds in subsequent monomeric units.