Hydrophobic and electrostatic interactions in the mixture hydrolyzed polyacrylamide-N-dodecylpyridinium chloride (AD37-DPC) in aqueous solution

International audienceThe interactions of oppositely charged polyelectrolyte and surfactant (anionic polyacrylamide AD37 and dodecylpyridinium chloride DPC, respectively) in aqueous solution were studied at 25 C by measurement of viscosity and conductivity. The system was investigated in aqueous medium in the absence and presence of NaCl. The AD37 interacts strongly with the DPC surfactant of the opposite charge. The interactions are electrostatic and hydrophobic. Thus, they are manifested in the formation of hydrophobic aggregates. The critical aggregation concentration (CAC) is much lower than the critical micellar concentration (CMC) of the surfactant alone. However, the value of the saturation concentration X 2 is higher. The ionic strength of the medium after addition of salt explains an important part of these interactions. In fact, the electrolyte charge affects the CMC and the CAC values