Association between branched poly(ethyleneimine) and sodium dodecyl sulfate in the presence of neutral polymers

By the addition of a suitable neutral polymer sterically stabilized colloidal dispersions of the poly(ethyleneimine)/sodium dodecyl sulfate nanoparticles can be prepared, which preserve their kinetic stability even at high ionic strengths. [Display omitted] ► PEO and PVP adsorb considerably onto the surface of PEI/SDS nanoparticles. ► Sterically stabilized PEI/SDS dispersions can be prepared. ► The stabilizing effect of neutral polymers decreases with decreasing pH. ► The kinetic stability of these dispersions can be maintained at high ionic strengths. ► The adsorption and stabilizing effect of dextran is not significant. In the present paper, the effect of different neutral polymers on the self-assemblies of hyperbranched poly(ethyleneimine) (PEI) and sodium dodecyl sulfate (SDS) has been investigated at different ionization degrees of the polyelectrolyte molecules. The investigated uncharged polymers were poly(ethyleneoxide), poly(vinylpyrrolidone) and dextran samples of different molecular mass. Dynamic light scattering and electrophoretic mobility measurements demonstrate that the high molecular mass PEO or PVP molecules adsorb considerably onto the surface of the PEI/SDS nanoparticles. At appropriate concentrations of PVP or PEO, sterically stabilized colloidal dispersions of the polyelectrolyte/surfactant nanoparticles with hydrophobic core and hydrophilic corona can be prepared. These dispersions have considerable kinetic stability at high ionic strengths where the accelerated coagulation of the PEI/SDS nanoparticles results in precipitation in the absence of the neutral polymers. In contrast, the addition of dextran does not affect considerably the kinetic stability of PEI/SDS mixtures because of its low adsorption affinity towards the surface of the polyelectrolyte/surfactant nanoparticles.