ANOMALOUS VISCOSITY BEHAVIOR OF RODLIKE POLYELECTROLYTES - PARTIALLY SULFONATED POLY(2-BENZOYL-1,4-PHENYLENE)S IN AQUEOUS-SOLUTION

Two stereoisomeric poly(2-benzoyl-1,4-phenylene)s were synthesized. Po lymer I has exclusively a head-to-tail structure; however, polymer II contains both head-to-head and head-to-tail units. The sulfonation rea ction of polymers I and II was found to occur mainly on the meta posit ion of the benzoyl group on the phenylene backbone. The viscosities of polymers Ia (27% sulfonated) and Ic (51% sulfonated) in aqueous solut ions at 25 degrees C were measured with and without NaBr addition. Upo n the addition of NaBr (0.05 and 0.1M), the reduced viscosities were f ound to increase gradually and reach a constant value in each case aft er standing at room temperature for 30-40 h. Without NaBr, the time ef fect was not found. The reduced viscosities of solutions with NaBr wer e also higher than those without the salt. These results are quite dif ferent from the typical ''polyelectrolyte'' behavior. A possible expla nation of the salt effect of rigid rodlike polymers such as sulfonated poly( 2-benzoyl-1,4-phenylene) is discussed. (C) 1998 John Wiley & So ns, Inc.