Polyether- and Tertiary Amine-Modified Silicone Surfactants: Synthesis and Surface Performance Across pH Ranges

In this study, polymerized silicone surfactants were modified with polyether and tertiary amine groups with the aim of improving the surface performance. Various PSiEO/(PO)-OH(CH3) surfactants were synthesized and their structures and performance were characterized through 1H NMR, FTIR spectroscopy, static surface tension, dynamic surface tension, zeta potential, and dynamic light scattering measurements. Subsequently, the modified silicones were incorporated as surfactants in aqueous solutions with different pH values. The surfactants with different hydrophobic/hydrophilic groups and end-capping groups exhibited different surface performances over a wide pH range. Thermodynamic parameters indicated that the micellization and adsorption of these surfactants were endothermic and spontaneous processes driven by entropy. The processes were hindered by increasing the solution pH and modification with hydrophobic groups. The aggregation behavior was significantly different under acidic, neutral, and basic aqueous conditions.