Novel nanocomplexes of hyperbranched poly(ethyleneimine), sodium dodecyl sulfate and dodecyl maltoside

Abstract

The aqueous complexes of poly(ethyleneimine) (PEI), sodium dodecyl sulfate (SDS) and dodecyl maltoside (C₁₂G₂) have been studied under dilute conditions using dynamic light scattering, electrophoretic mobility, surface tension and pH measurements. According to the surface tension data the complexation between PEI and C₁₂G₂ can be neglected while a strong interaction was detected between PEI and SDS. The charged nature and size of the PEI–SDS–C₁₂G₂ complexes vary in a similar manner with SDS concentration as for the PEI–SDS systems. At large excess of SDS a kinetically stable colloid dispersion of the compact PEI–SDS–C₁₂G₂ particles forms.

The electrophoretic mobility measurements indicate that the charge reversal of the PEI molecules occurs at lower SDS concentrations in the presence than in the absence of dodecyl maltoside. The enhanced charge inversion of PEI affords a significant extension of the concentration range with kinetically stable dispersion of the polyelectrolyte–surfactant nanoparticles compared with the PEI–SDS system. The pH of the PEI–SDS–C₁₂G₂ mixtures also reveals a peculiar dependence on the surfactant concentration. These latter findings are explained by the synergistic binding of the ionic and non-ionic surfactants to both the uncharged and charged amine groups of the PEI. It can be concluded that the addition of sugar surfactants is an efficient way to increase the kinetic stability and manipulate the pH of the mixtures of oppositely charged weak polyelectrolytes and surfactants.