Hydrophobic interactions in the binding of polyvinylpyrrolidone

A spectrophotometric method was used for the quantitative determination of binding in the poly‐vinylpyrrolidone–rose bengal system. Binding of tiron, another anionic dye, onto polyvinylpyrrolidone was investigated by equilibrium dialysis. Comparison of binding constants of the two systems indicated the importance of hydrophobic interactions in binding. Because rose bengal can serve as a fluorescent probe, a fluorimetric method was also used and the increase in fluorescence confirmed the significance of hydrophobic interactions in the binding of the dye onto the polymer.