Synthesis and Properties of Novel Double‐Tail Trisiloxane Surfactants with High Spreading Ability

A new type of double‐tail trisiloxane surfactants of the general formula R1NR2CH2CH(OH)CH2O(CH2CH2O)xCH3 (x = 8.4, 12.9, 17.5, 22; R1 = Me3SiOSiMe(CH2)3OSiMe3, R2 = CH2CH(OH)CH2OR3, R3 = CH2CH(C2H5)CH2(CH2)2CH3) has been synthesized by reacting single‐tail trisiloxane surfactants with 2‐ethylhexyl glycidyl ether. Their structures were characterized with 1H‐NMR and 13C‐NMR spectroscopy. These double‐tail trisiloxane surfactants reduce the surface tension of water to less than 24 mN/m at a level of 10−5 mol/L. The spreading ability (SA) of the double‐tail trisiloxane surfactant solution on Parafilm (or Ficus microcarpa leaf) surfaces is better than that on polyethylene terephthalate surface. The SA of the solution of the double‐tail trisiloxane surfactants 1J with average ethoxy units of 8.4 is far better than the others, and its solution (5.0 × 10−3 mol/L) possesses an SA value of over 15 within 10 min on Parafilm and Ficus microcarpa leaf surfaces. The surface tension values of aqueous solutions (1.0 × 10−3 mol/L) of the double‐tail trisiloxane surfactants 1J are still less than 25 mN/m over 21 days in an acidic environment (pH 4.0) and 139 days in an alkaline environment (pH 10.0), respectively. It is suggested that the SA and hydrolysis resistance of double‐tail trisiloxane surfactants are able to be improved by changing the structure of the hydrophobic group, such as increasing the molar ratio of methyl to methylene.