Properties of a phenyl-substituted polyphenylene in dilute solution

• Published in: Journal of polymer science. Polymer symposia 1978, Vol.65 (1), p.125-141
• Main Authors: Work, James L., Berry, Guy C., Casassa, Edward F., Stille, John K.
• Format: Article
• Language: English
• ISSN: 0360-8905; 1936-0959
• DOI: 10.1002/polc.5070650114

Three preparations of a phenyl‐substituted polyphenylene were fractionated and studied in solution by light scattering, osmometry, viscometry, fluorescence depolarization, and exclusion chromatography. Three of the five main‐chain phenylene groups in the repeat unit are linked para, but the other two may be either meta or para, with the latter linkage predominating. The data are consistent with a chain structure characterized by rigid segments about 70–75Å long, on the average, joined with 120° bond angles, about which virtually free rotation is allowed. For chains of up to about 250 backbone phenylene units, the hydrodynamic behavior in tetrahydrofuran, and other solvents, is that of a freely draining coil with intrinsic viscosity proportional to molecular weight. The effect of intramolecular excluded volume on chain conformation is negligible, although intermolecular interactions are reflected by a positive second virial coefficient (in tetrahydrofuran). Study of polymers of higher molecular weight is hampered by formation of what appear to be metastable aggregates resembling randomly branched chains.