Diffusion and scaling behavior of polymer-surfactant aggregates.

Abstract

The self-diffusion coefficient of poly(ethyleneoxide) (PEO) in self-assembled aggregates of PEO and sodium dodecyl sulfate (SDS) in water at PEO concentrations well below the overlap point has been determined by pulse gradient spin echo NMR spectroscopy. The results show that individual polymer coils undergo significant expansion upon complexation with the surfactant. The diffusion coefficients of PEO coils saturated with SDS scale with molecular weight of the polymer as $D\ensuremath{\sim}{M}^{{\ensuremath{\nu}}_{\mathrm{app}}}$ with ${\ensuremath{\nu}}_{\mathrm{app}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.60\ifmmode\pm\else\textpm\fi{}0.02$. The value of ${\ensuremath{\nu}}_{\mathrm{app}}$ in this case is different from ${\ensuremath{\nu}}_{\mathrm{app}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.55\ifmmode\pm\else\textpm\fi{}0.01$ for the surfactant free coil.