COMPLEX-FORMATION BETWEEN SODIUM DODECYL-SULFATE AND POLY(4-VINYLPYRIDINE N-OXIDE)

The interaction of poly(4-vinylpyridine-N-oxide)(PVPNO) with sodium do decyl sulfate in aqueous solutions was examined using surface tension, turbidimetry, and light scattering (quasielastic, electrophoretic, an d total intensity light scattering). Surface tension measurements show that the polymer begins to interact with SDS at a concentration below the critical micelle concentration (cmc), in a manner similar to the behavior of other nonionic polymer-surfactant systems (e.g., PEO-SDS). Turbidimetric and quasielastic light scattering (QELS) studies at SDS concentrations much above the cmc clearly reveal the formation of a s oluble polymer-micelle complex. On the other hand, phase separation, s imilar to that observed for polyelectrolyte-oppositely charged micella r systems, occurs at low pH, presumably as a consequence of protonatio n of the polymer to form a polycation. Total intensity data show satur ation of the polymer with bound micelles at high SDS concentration, wh ile QELS measurements clearly reveal two peaks: one corresponding to f ree micelles and the other to the complex. Quasielastic and electropho retic light scattering measurements were carried out on mixtures of SD S and PVPNO, SDS and PEG, or SDS and both polymers. These indicate tha t the binding of SDS micelles to PVPNO in 0.10 M NaCl is not as strong as the binding to PEG.