STATIC LIGHT-SCATTERING OF POLYELECTROLYTE MICELLE COMPLEXES

Soluble complexes are formed between poly(dimethyldiallylammonium chloride) and anionic/nonionic mixed micelles of sodium dodecyl sulfate and Triton X-100, at certain well-defined micelle compositions and ionic strengths. Static light scattering has been used to characterize the complexes generated from a 2 X 105 MW sample of this polycation and mixed micelles with 0.35 mol fraction anionic surfactant, at an ionic strength of 0.40 M. Measurements were carried out for polyion-micelle complexes at polymer concentrations ranging from 0.0025 g L-1 to 0.8 g L-1, for surfactant-free polymer solutions, and for polymer-free micelle solutions. In the low polymer concentration range (<ca. 0.1 g L-1) the results are consistent with intrapolyion complexes, with dimensions comparable to those of the free polymer, in which 10-20 micelles are bound. At higher polymer concentrations, higher order aggregates form. For a polymer sample with nominal MW of 2 X 106, such higher order aggregates appear to be present even at very low concentrations. The results suggest an equilibrium between intrapolymer and multipolymer complexes, that depends, inter alia, on polymer-micelle stoichiometry and on polymer chain length. © 1990, American Chemical Society. All rights reserved.