Synthesis And Properties Of The Triazine Ring Sulfonate Gemini Surfactant

Gemini surfactants represent a new class of surfactants, which is made up of two amphiphilic moieties covalently connected at the level of the head groups or very close to the head groups by a spacer group. Compared with traditional surfactants, Gemini surfactants have higher surface activity, better water solubility, much lower Krafft temperatures, unique rheology behavior, lime soap dispersing property and interaction with traditional surfactants. So they have bright application foreground in the emulsion, washing, solubilization and other industrial fields.Eight s-triazine sulfonate gemini surfactants, C_m-s-C_m (m=6,8,12,14; s=2,3), were synthesized from cyanuric chloride, aliphatic amine, taurine, ethylenediamine and 1,3-propanediamine. The chemical structures of the prepared compounds were confirmed by 1H NMR, 13C NMR, IR spectra and ESI-MS. In addition, their surface activity and applied properties were studied.Their critical micelle concentrations (CMC) in the aqueous solutions at 25-5 were determined by surface tension and electrical conductivity methods. With the increasing length of the carbon chain, the values of their CMC initially decreased and then reached a minimum (respectively 3.34×10^-5℃mol L^-1 and 7.23×10^-5 mol L^-1 when the carbon number was 14, but increased with the carbon number of 16. The values of CMC of Gemini surfactants C_m-s-C_m are about one or two orders of magnitude lower than that of the monomeric surfactant sodium dodecyl sulfate. Results showed that Gemini surfactants have much higher surface activity than traditional ionic surfactants. In addition, with the increasing length of the carbon chain, the values of theirγ_cmc increased at first and then decreased. The minimum value is 33.57 mN/m.The standard free energy micellization and adsorption (ΔG_mic°andΔG_ads°) were calculated according to the mass action model. The results indicated that the anionic Gemini surfactants have great ability to form micelles in solution and to adsorb at the air–water interface, and the adsorption is promoted more than the micellization. Meanwhile, the properties for application of the C_m-s-C_m were also investigated. The wetting ability and lime soap dispersing power of C_m-s-C_m decreased with the increasing length of the carbon chain, while the emulsification stability were rising gradually. The C₆-s-C₆ and C₈-s-C₈ possess better wetting ability and lime soap dispersing power. They are suitable for use as dispersants.