Effect of pH and surfactants on the electrokinetic properties of nanoparticles dispersions and their application to the PET fibres modification

Abstract

This paper presents the effect of surfactants, pH and electrolyte (0.1 × 10−3 M KCl) on the stability of the aqueous dispersions of commercial ZnO and AgCu nanoparticles. As the surfactants cationic hexadecyltrimethylammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS), and nonionic 4-(1,1,3,3-tetramethylbutyl)phenyl polyethylene glycol (Triton X-100) at concentrations of 0.5 × 10−3, 1.0 × 10−3, and 0.1 × 10−3 M, respectively, were used. The zeta potential values, z-average hydrodynamic diameter and long-term stability of ZnO and AgCu nanoparticles were examined by means of the dynamic light scattering (DLS) technique. It was found that the presence of ionic surfactants reduced the tendency of nanoparticles for agglomeration/aggregation and improved their colloidal stability. They were characterized by high (>|70| mV) and pH-independent zeta potential values. In addition, ZnO nanoparticles in the presence of ionic surfactants showed a better long-term stability than AgCu nanoparticles. Their z-average hydrodynamic diameters in CTAB and SDS were 195 ± 2 nm and 295 ± 5 nm, respectively, and remained almost unchanged for 5 days. The addition of KCl improved the stability of aqueous and containing nonionic surfactant dispersions of nanoparticles, what was reflected in the zeta potential values > 30 mV in almost the entire pH range. The stability of nanoparticles dispersion significantly affects the uniformity of nanoparticles distribution on the fibres surface. The uniformity of distribution of the ZnO and AgCu dispersion on the surface of polyester (PET) fibres was carried out by means of microscopic methods (SEM/EDS).