New family of Gemini surfactants with glucosamide-based trisiloxane

The interfacial properties of a new family of glucosamide-based trisiloxane Gemini surfactants of the general formula (CH2OCH2)n(Me3SiOSiMeR1OSiMe3)2 (R1 = (CH2)3NR2(CH2)2NHCO(CHOH)4CH2OH; R2 = CH2CH(OH)CH2OCH2, n=0, 1, and 2) were studied. Members of this family reduced the surface tension of water to approximately 21 mN/m at concentration levels of 10−4 mol/l and 10−5 mol/l. The physicochemical parameters of these dimeric compounds were compared with those of the corresponding monomer. The CACs of the geminis were about two orders of magnitude lower than that of the monomer. The effect of the spacer functionality on the behavior of these surfactants was analyzed. The CAC values of the homologues increased with increased the number of the oxyethylene units of the surfactant spacer.