Effect of organic salts on the aggregation behavior of tri-(trimethylsiloxy)silylpropylpyridinium chloride in aqueous solution

- The organic salts affect the aggregation and surface activity of cationic silicone surfactant.
- Spherical-like structured aggregates were obtained in all mixed solutions may have potential applications in many fields.
- The adsorption of Si4pyrCl at the interface is stronger than the aggregation in solution.

In this study, we synthesized the cationic silicone surfactant tri-(trimethylsiloxy)silylpropylpyridinnium chloride (Si4pyrCl). We then systematically investigated the effects of organic salts such as sodium acetate, sodium oxalate, sodium citrate, sodium benzoate, and sodium salicylate on the aggregation behavior of Si4pyrCl in aqueous solution through surface tension and electrical conductivity analyses, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The addition of organic salts promoted surfactant aggregation. The aggregation ability was observed to be in the following order: s sodium salicylate > sodium benzoate > sodium citrate > sodium oxalate > sodium acetate. The measurement of electrical conductivity shows that the micellization of Si4pyrCl in aqueous solution is spontaneous. Several spherical-like aggregates with a diameter of approximately 500 nm were observed via TEM. The diameter distribution was determined through DLS. This work will be of great significance for the understanding of cationic silicone surfactants and their applications in industrial production.

The Figure shows the surface tension curves of Si4pyrCl with sodium acetate at different concentrations. The CMC values of Si4pyrCl decrease in the presence of organic salts and it drops with the increasing of the ionic strength.88