Normal-mode analysis of infrared and Raman spectra of crystalline isotactic poly(methyl methacrylate)

Calculations have been done for single chain 5/1 and 10/1 helical backbone conformations. Best agreement in the low-frequency region is found between the observed and calculated frequencies for the 10/1 structure. Infrared and Raman bands over the entire spectral region can be satisfactorily interpreted on the basis of the potential energy distributions and dispersion curves for the 10/1 helical conformation of the single i-PMMA chain in the double-stranded structure