Transition and Relaxations in Polyquinoxalines

Abstract

Completely aromatic polymers, such as the polyquinoxalines offer a unique opportunity for studying molecular motions, in particular, motions responsible for transitions and relaxation effects. In ordinary linear aliphatic hydrocarbon polymers, for example, paraffinic systems, relaxation processes are believed to originate in rotations, either of whole chains, chain segments, individual moieties or even atoms within a molecular unit (1,2). In fully aromatic polymers internal torsional (and even more so rotational) mobility is greatly restricted due to resonance overlap and steric effects (i.e., high barriers to rotation arising from ortho substituents). Consequently, we expect primary motions such as glass or melt transitions and associated relaxations to be manifested in translational rather than rotational interactions.