SOLUTION BEHAVIOR OF LIGHTLY SULFONATED POLYSTYRENE AND POLY(STYRENE-CO-4-VINYLPYRIDINE) COMPLEXES IN DIMETHYLFORMAMIDE

The solution behavior of blends of lightly sulfonated polystyrene (SPS) and poly(styrene-co-4-vinylpyridine) (PSVP) was studied as a function of blend composition, copolymer composition, the SPS counterion, and solvent polarity. Complexation between PSVP and metal-neutralized SPS occurred in dimethylformamide (DMF) solutions, but no intermolecular interactions were noticeable for blends containing the sulfonic acid derivative. A maximum in the viscosity occurred at a vinylpyridine to sulfonate ratio of ca. 6:1. This ratio was found to be relatively independent of solvent polarity, composition of the copolymers, and the cation used. The magnitude of the viscosity maximum, however, increased with decreasing solvent polarity and with increasing functionality of the two polymers. Transition metal cations formed the strongest interactions as judged by the largest viscosity increase. The viscosity of blends using the alkali and alkaline earth metal salts of SPS decreased with increasing electrostatic field strength (q/r) of the cation. The solution viscosity for the blends in a mixed solvent of toluene/methanol (95/5v/v) was thixotropic, but the viscosity increased slowly when the shear deformation was stopped.