CONFORMATIONAL-ANALYSIS OF HIGHLY EXTENDED POLY(ETHYLENE-TEREPHTHALATE) CHAINS BY MONTE-CARLO CALCULATIONS

The conformational disorder compatible with the highly extended chains found in mesomorphic poly(ethylene terephthalate) has been studied by Monte Carlo calculations on model oligomers confined inside cylindric al tubes. The distribution of torsional angles for such extended chain s is characterized by O-C-C-O bonds being always in the trans domain, while the C-O-C-C bonds show an approximately similar probability of b eing found in trans and gauche states, the probability maxima being ce ntered at 90 degrees and -90 degrees in the latter cases. At variance with the torsional angles of the O-C-C-O and the ester bonds, always v ery close to 180 degrees, the distributions for all other torsional an gles show flat and broad probability maxima, indicating the possibilit y of substantial deviations from the average value inside each domain. This is also true for the fictitious O-(CC)-C-...-O bonds across the phenylene rings, for which a nearly trans geometry is preferred in ext ended conformations.