RIGID-ROD POLYAMIDES BASED ON 2,2',6,6'-TETRASUBSTITUTED BIPHENYLS - SYNTHESIS, CHARACTERIZATION, AND STRUCTURES

Polyamides based on 4,4'-diamino-2,2',6,6'-tetrasubstituted biphenyls and phenylterephthalic phthalic acid have been synthesized, and the st ructures and properties of this series of polymer have been studied. I t is shown that the polymers have an amorphous structure although some degree of short-range order is present. This class of polymer, while consisting of comparatively stiff rodlike molecules, demonstrates high solubility and low glass transition temperatures. The behavior is due to the combination of the noncoplanar conformation of the twisted bip henyl and the fact that they have bulky side groups in the 2,2'- and 6 ,6'-positions that weaken the interchain interactions (like hydrogen b onding and van der Waals forces) and frustrate parallel packing of the polymer chains. (C) 1994 John Wiley & Sons, Inc.