POLYMER-SURFACTANT INTERACTIONS DEMONSTRATED BY A KINETIC PROBE - DEGREE OF IONIZATION

The effects of aggregates of poly(ethylene oxide) (PEG), poly(vinyl py rrolidone) (PVP) and sodium dodecyl sulfate (SDS) in solution on the r ates of acid-catalyzed hydrolysis of 2-(p-nonoxyphenyl)-1,3-dioxolane (p-NPD) were investigated. Comparisons of the rate vs. SDS concentrati on profiles in the absence and presence of polymer, show significant i nhibition as a function of PEO and PVP concentrations. The observed fi rst-order rate constant vs. SDS concentration profiles, in the presenc e of polymer, exhibit three distinct regions, as extensively documente d for SDS. The transitions observed in the kinetic profiles coincide w ith the discontinuities in the specific conductivity vs. SDS concentra tion plots in the presence of polymers, and correspond to the critical aggregation concentration (CAC) and polymer saturation point (PSP). T he degree of ionization of PVP-SDS complexes (0.38 +/- 0.01) was estim ated by conductivity measurements by using the Evans equation.