Syntheses and Properties of Novel Ionic Twin-tail Trisiloxane Surfactants

Abstract

Abstract To improve the hydrolysis resistant ability (HRA) of ionic trisiloxane surfactants, three novel ionic twin-tail trisiloxane surfactants have been synthesized. Their formulas are of (R)2N+(CH3)2I− (A), (R)2N(CH2)3SO3 −Na+ (B) and (R)2N+ (I)− (CH3)(CH2)3SO3 −Na+ (C) [R = Me3SiOSiMe(CH2)3OSiMe3], respectively. Their structures were characterized by ESI-MS, 1H-NMR and 13C-NMR spectroscopy. The surface activity and hydrolysis resistance of the synthesized ionic twin-tail trisiloxane surfactants are significantly better than that of the ionic single-tail analogue surfactants. The critical aggregation concentration (CAC) values of these ionic twin-tail trisiloxane surfactants are at levels of 10−6∼10−5 mol L−1 and the surface tension (γ) values of their aqueous solutions at CAC are below 21.0 mN m−1. The γ values of the aqueous solutions of anionic trisiloxane surfactant B and zwitterionic trisiloxane surfactant C are still less than 21 mN m−1 after having been placed in alkaline environment (pH 10.0) for 29 days. However, the spreading ability (SA) of their aqueous solutions on low-energy solid surfaces is not as good as that of the nonionic twin-tail trisiloxane surfactants previously prepared by us. By weight loss methods the cationic trisiloxane surfactant A was confirmed to be able to use as a corrosion inhibitor. The structure and surface area per molecule (as m) of zwitterionic surfactant C were also discussed.