CONFORMATIONAL EFFECTS AND CONFIGURATIONAL SPLITTING IN C-13 NMR-SPECTRA OF SYNTHETIC-POLYMERS AS INVESTIGATED BY AB-INITIO INDIVIDUAL GAUGES FOR LOCALIZED MOLECULAR-ORBITALS (IGLO) CALCULATIONS

The inhomogeneous broadening of solid state C-13 spectra of glassy pol ymers and the configurational splitting observed in solution spectra a re analyzed by a unifying approach. The method combines conformational statistics and ab initio IGLO calculations to obtain simulated solid state and solution spectra. A number of polymers of different structur al classes are investigated, including poly(ethylene), atactic poly(pr opylene), poly(vinyl chloride), and poly(methyl methacrylate). For mos t systems a remarkable degree of agreement between simulation and expe riment is achieved for both the solid state NMR and the configurationa l splitting. Furthermore, the influence of geometric parameters on the chemical shift, the validity of the gamma-gauche effect, an MO analys is, and the role of the anisotropic part of the chemical shift tensor as a source of structural information are considered.