Dilute and concentrated solutions of a heterocyclic polymer (BBB)

Abstract

Properties of the heterocyclic polymer prepared by the reaction of naphthalene-1,4,5,8-tetracarboxylic acid with 3,3′-diaminobenzidene are discussed. Light scattering, viscometric and freezing point depression measurements on dilute solutions lead to the conclusion that in strong acids BBB is protonated and takes on a flexible coil conformation in dilute solutions. Viscometric data on concentrated solutions likewise follow the behaviour expected for coiled chains, but exhibit the behaviour expected for entangled chains at unusually low concentrations, and a segmental mobility that decreases rapidly with increasing polymer concentration. These data, together with X-ray diffraction studies on the undiluted polymer, are discussed in terms of short range interactions leading to stacked aggregates in very concentrated solutions and the bulk polymer.