SURFACTANT POLYMER ASSEMBLIES - 2 - POLYELECTROLYTE PROPERTIES/

The polyelectrolyte nature of the aggregates formed between neutral po lymer, poly(vinyl pyrrolidone) (PVP) and anionic surfactant, sodium do decyl sulfate (SDS) is demonstrated via their light scattering behavio r. Adding SDS to neutral PVP is similar to electrostatically charging a neutral polymer, thereby increasing electrostatic excluded volume ef fects and decreasing osmotic compressibility and light scattering. Sim ilarly, once formed, the behavior of these aggregates with respect to ionic strength resembles that of normal linear polyelectrolytes; namel y, increasing ionic strength decreases their interactions, as measured by A(2), and decreases their R-g. Using combined electrostatic persis tence length and excluded volume models, the main features of these ph enomena are semiquantitatively described. Because SDS exists in multip le equilibria in the PVP/SDS solutions, the system is more complex tha n normal linear polyelectrolytes, and so the PVP/SDS aggregates also e vidence behavior distinct from traditional polyelectrolytes.