Ordering and intramolecular mobility in the nematic phase of PAA investigated by means of NMR lineshape analysis and computer simulations of the lineshape

We have recorded the 1H- and 2H-NMR spectra of PAA, PAA-d6, and PAA-d8. The order parameter S = Szz = 1/2. < 3 cos2 θ - 1 > has been determined from the different types of NMR experiments and shown to be quite sufficient for the interpretation of both proton and deuterium NMR data since the values of the tentatively calculated second order parameter Sxx- Syy (from 2H- resonance of PAA-d8) are very small. From a comparison of the proton NMR spectra of PAA-d6 and PAA and theoretical spectra computed using an approximative procedure for different kinds of intramolecular motions some conclusions are drawn concerning intramolecular mobility of the PAA molecules.