TRIS MODIFIED SILICONE SURFACTANTS AND THEIR INTERACTIONS WITH PROTEINS

Abstract

Tris modified silicone surfactants were prepared and surface activities ofthis class of silicone surfactants were examined. To attach Tris to silicone backbone, several possible synthetic routes were investigated, and the best approach was established. Using the optimal reaction conditions, Tris modified silicone surfactants were obtained in overall good yield (75-80%). The physiochemical properties, including surface activity, hydrolytic stability, and pH profiles of the prepared Tris modified oligosilicone were fully examined and compared with related compounds that did not contain silicone. It was demonstrated that Tris modified 1,1,1,3,5,5,5-heptamethyltrisiloxane possesses moderate buffer capacity and an excellent activity in lowering surface tension of aqueous solutions. The foaming behaviors of this class of silicone surfactant were strongly dependent on the pHs of the aqueous solutions. However, the utility of this branched trisiloxane surfactant was compromised by its propensity to hydrolyze on contact with aqueous solutions, especially in acidic or basic media. In order to understand the role silicone surfactants can play in stabilizing proteins and enzymes in water-in-silicone emulsions, the protein-silicone surfactant interactions were studied using the interfacial tension method. It was determined that both electrostatic interactions between hydrophilic groups of functional silicone and protein molecules, and steric anchoring effects play a part in lowering the interfacial tension of water/silicone oil interfaces.