Syntheses and Properties of New Double-tail Trisiloxane Surfactants with Both Hydrolysis Resistance and High Spreading Ability

Abstract

Abstract New double-tail trisiloxane surfactants of the general formula R1NR2CH2CH(OH)CH2O(CH2CH2O)xCH3 (R1 = Me3SiOSiMe(CH2)3 · OSiMe3; R2 = Me3SiOSiMe((CH2)3OCH2CH(OH)CH2)OSiMe3; x = 8.4, 12.9, 17.5, 22) have been synthesized. The spreading ability (SA) values of the double-tail trisiloxane surfactants solutions (1.0 × 10−3 mol/L) with average ethoxy units of 8.4, 12.9 and 17.5 on ficus microcarpa leave surface are more than 9 within 3 minutes, and their SA values on the parafilm surface are over 15 within 10 minutes at a concentration of 5.0 × 10−3 mol/L. In alkaline environment (pH = 10.0) the hydrolysis resistant ability (HRA) of the double-tail trisiloxane surfactant containing average ethoxy units of 8.4 with the surface tension of aqueous solution (1.0 × 10−3 mol/L) of less than 23 mN/m over 170 days, is far better than the others’. It is suggested that a more flexible spacer between hydrophobic groups and hydrophilic groups in double-tail trisiloxane surfactants molecules, not only can improve their SA on low-energy solid surfaces, but also improve their HRA.