INTERACTION BETWEEN POLYELECTROLYTE AND SURFACTANT OF OPPOSITE CHARGE - HYDRODYNAMIC EFFECTS IN THE SODIUM HYALURONATE TETRADECYLTRIMETHYLAMMONIUM BROMIDE SODIUM-CHLORIDE WATER-SYSTEM

The interaction between the negatively charged polyelectrolyte sodium hyaluronate and the positively charged ion of the surfactant tetradecyltrimethylammonium bromide (TTAB) has been investigated in water solution. The properties of the system have been monitored by measuring the solution viscosity, surface tension, and phase equilibrium properties for increasing sodium chloride concentrations. On addition of TTAB and at low ionic strength the solution separates into two phases. If the salt (sodium chloride) concentration is sufficiently high (in the present case approximately 200 mM), a homogeneous system is obtained. Just above this critical salt concentration the solution viscosity passes through a marked minimum as the TTAB concentration is increased. At higher salt concentration the viscosity behavior becomes almost identical to that of a solution without TTAB. The effect is tentatively explained as an initial decharging of the polyelectrolyte accompanied by contraction of the coil and partial aggregation. At higher TTAB contents the adsorption leads to expanded chains and possibly deaggregation.