Synthesis and Properties of Novel Double‐Tail Trisiloxane Surfactants

Abstract

To improve the hydrolysis resistant ability of trisiloxane surfactants, ethoxylated single-tail and doubletail trisiloxane surfactants of the general formulas Me 3 SiOSiMeR 1 OSiMe 3 (R 1 = (CH 2 ) 3 NHCH 2 CH(OH)CH 2 (OCH 2 CH 2 ) x OCH 3 ; x = 8.4, 12.9, 17.5, 22) and Me 3 SiOSiMeR 2 OSiMe 3 (R 2 = (CH 2 ) 3 NR 3 CH 2 CH(OH)CH 2 (OCH 2 CH 2 ) x OCH 3 ; R 3 = CH 2 (CH 2 ) y CH 3 ; x = 8.4, 12.9, 17.5, 22; y = 2, 6) were synthesized. Their structures were characterized by 1 H NMR and 13 C NMR. The surface activity and hydrolysis resistant properties of the trisiloxane surfactants prepared were also studied. The values of the critical micelle concentration of all trisiloxane surfactants prepared were at levels of 10 -5 and 10 -4 mol/L. They can reduce the surface tension of water to less than 24 mN/m. The hydrolysis resistant properties of double-tail trisiloxane surfactants are superior to those of single-tail trisiloxane surfactants. The double-tail trisiloxane surfactants 1B (x = 8.4; y = 2) and 2C (x = 12.9; y = 6) can be stable for 8 days in an acidic solution (pH 4.0) and 11 days in an alkaline environment (pH 10.0).

Influence of Substructures on the Spreading Ability and Hydrolysis Resistance of Double‐Tail Trisiloxane Surfactants

“…Type A single-tail trisiloxane surfactants (1A, 2A, 3A, and 4A), whose structures are shown in Scheme 1, were synthesized as described in our previous report [19]. Paraffin wax was purchased from Shanghai Specimen and Model Factory, China.…”

“…One difference is that the used solvent is toluene, rather than methanol in procedure (b). Procedures (c) and (d) were carried out in the light of the reference [19].…”

“…The 1 H-and 13 C-NMR spectra of double-tail trisiloxane surfactants prepared were analyzed according to the rule that different chemical environments of H and C result in different chemical shifts, and by comparing the chemical shifts of related compounds [19,22,23], The assignments of the chemical shifts in 1 H-and 13 C-NMR spectra of 1E, IF, 1G and 1H are listed in Tables 1 and 2. Structural Characterization 1 H-and 13 C-NMR spectroscopy analyses were carried out with a Varian Mercury-plus 300 spectrometer in CDCl 3.…”

“…Aqueous solution surface tension (c) values were obtained by the Wilhelmy plate method using a BZY-1 completely automatic surface tensiometer (Shanghai Equity Instruments Factory, China). The critical micelle concentration (CMC) values, the Scheme 1 Synthesis route to double-tail trisiloxane surfactants surface tension at CMC (c cmc ), the SA and HRA were determined as reported elsewhere [19].…”

“…It is also known that the incorporation of a methyl group in the spacer of a trisiloxane surfactant is able to improve its hydrolysis resistance [13]. Consequently, to accumulate the previously mentioned features, we synthesized a series of new double-tail trisiloxane surfactants [19]. It was found that their hydrolysis resistant ability (HRA) is greatly improved with respect to original singletail trisiloxane surfactants, but that their spreading performance is not satisfactory.…”