Conformational characteristics of polystyrene

Abstract

Abstract Conformational energies, computed with a forcefield including coulombic interactions and a simple accounting for the effects of solvent, of meso and racemic 2,4‐diphenylpentane as model substances of polystyrene have been computed as functions of the skeletal torsion angles and the phenyl torsion angles. The relatively high energies of the ḡ conformations rendered these states negligible and no minimum was found in the meso‐tt domain. Three minima for the meso diad ( gt, tg, gg ) and four minima for the racemo diad ( tt, tg, gt, gg ) are relevant. A two‐state rotational isomeric state model is applicable with states at φ t = 5°C and φ g = 110° for both meso and racemo diads. Statistical weight matrices have been derived and values predicted for the characteristic ratio, the fractions of 2,4‐diphenylpentane and 2,4,6‐triphenylheptane at stereo‐chemical equilibrium and the vicinal NMR coupling constants are found to be consistent with experimental results.