SYNTHESIS, SOLUTION RHEOLOGY AND INTERFACIAL BEHAVIOR OF SULFONATED RIGID ROD POLYMERS

Sulphonated poly(p-phenylene terephthalamide) copolymers (S-PPTA) spanning a wide range of sulphonation were synthesized from their nonionic precursor through a metalation reaction. Sulphonation was accomplished with butane sultone. Solution behaviour was examined. For example, it was shown that the copolymers were water soluble at sulphonate levels greater than approximately 40 mol%. Rheological measurements show that although the molecular weight of these rigid rods are low, inter-chain hydrophobic-type associations have a profound influence on solution properties. The level of hydrophobicity is controlled directly by the sulphonate content. Preliminary observations of concentrated solutions indicate the absence of ordered structures. However, thin, bulk films are highly birefringent indicating the presence of large ordered structures. Finally, thermal measurements of these films shows a high degree of thermal stability which is in marked contrast with the deterioration in solution properties at substantially lower temperatures. The latter phenomenon can be ascribed to the hydrolysis of the amide linkages. © 1990.