Dilute Solution Properties and Conformation of Polyacenaphthylene

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Abstract
Several polymerization techniques were investigated to obtain high molecular weight polyacenaphthylene. Thermal polymerization was found to yield molecular weights of over 2,000,000. A number of polyacenaphthylene fractions were characterized by means of light scattering, osmotic pressure, and viscosity determinations in a theta solvent and in benzene. The following intrinsic viscosity, molecular weight relationships were established: Although considerable hindrance to rotational motion of chain segments should be expected, the solution behavior could be interpreted in terms of current two-parameter theories for flexible chains. The theta dimensions determined by light scattering were in agreement with those estimated from intrinsic viscosity, and were found to be comparable to those for polystyrene. Also, application of first-order perturbation theory to second virial coefficient data yielded reasonable estimates of the radius of gyration. The high degree of internal consistency among the various measurements rules out the occurrence to any significant extent of branching reactions during thermal polymerization. Examination of molecular models indicates that threodiisotactic is by far the most probable of the four possible stereoconfigurations. Thus steric considerations along with crystallinity which was observed in all samples suggest considerable stereoregularity.

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