Quasielastic and electrophoretic light scattering studies of polyelectrolyte-micelle complexes

Abstract

The aqueous system comprised of poly(dimethylammonium chloride) (a strongly cationic polymer) and a mixture of sodium dodecyl sulfate and Triton X-100 (anionic/nonionic mixed micelles) forms polyelectrolyte-micelle complexes. At suitable micelle compositions and ionic strengths, soluble complexes are formed, which may be studied by a variety of solution techniques, including quasielastic light scattering. In this report, the authors examine the influence of polymer molecular weight and micelle composition on the nature of these complexes. Multiangle measurements were made with two different instruments (hence different procedures for extracting apparent size distributions from measured autocorrelation curves). At the concentrations employed, multipolymer complexes appear to form. The QELS data, taken in conjunction with limited electrophoretic light scattering results, suggest that the main determinant of the extent of higher-order aggregation are those factors influencing the net charge of a 'primary' i.e. intrapolymer complex, with molecular weight per se playing a secondary role.