The interaction between polyvinylpyrrolidone (PVP) and zwitterionic surfactant tetradecylbetaine (C~1~4BE) has been investigated by means of surface tension and time resolved fluorescence measurements. It is shown that the addition of PVP results in a decrease of the aggregation number of C~1~4BE and an appearance of two transition points in the surface tension- concentration curve. The results indicate that PVP associates with C~1~4BE to form aggregate by the hydrophobic effect between hydrophobic groups and electrostatic force between polar head groups of C~1~4BE and PVP.

Key words: MICELLE, SURFACE ACTIVITY, POLYVINYLPYRROLIDONE, SURFACE TENSION, BETAINE, AMPHOTERIC SURFACTANTS, INTERACTIONS, AGGREGALES, TETRADECYL, AGGREGATION NUMBER