Synthesis And Physicochemical Investigation Of Cationic Gemini Surfactant Derived From Cyanuric Chloride

Compared with traditional surfactants, Gemini surfactants 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. As a new generation of surfactants, because of better biodegradability, lower toxicity, superior performance and other characteristics, cationic Gemini surfactants is receiving widespread attention by researchers.Six novel quaternary ammonium salt cationic Gemini surfactants C_n-m-C_n(n=6,8,12;m=2,3,4,6) were synthesized from 2,4,6–trichloro–1,3,5–triazine, ethylenediamine, N,N–dimethylpropane–1, 3–diamine and benzyl chloride. 1H NMR, 13C NMR and ESI–MS spectra were used to confirm the chemical structures of the prepared compounds. Studied their surface activity, micelle formation and surface adsorption thermodynamics, emulsification, wetting, lime soap dispersing power and micellar aggregation number.Their critical micelle concentrations (CMC) in the aqueous solutions and the minimum surface tension (γCMC) were determined by surface–tension and electrical conductivity respectively. For the series of C_n-2-C_n,with the increasing length of the hydrophobic chain (from 6 to 12), the values of their CMC reduced from 3.75×10^-4mol / L to 5.30×10^-6mol / L, the values of theirγCMC value increased gradually from33.8mN / m to 45.5mN / m. For the series of C₆-m-C₆, with the bridge length of carbon chain increased from 2 to 6, the values of their CMC initially increased and then decreased. When the bridge is 4, the CMC reached a minimum, as low as 3.71×10^-5mol / L.According to the mass action model, calculated the standard free energy micellization and adsorption (â–³G^°_mic andâ–³G^°_ads). The results showed that the cationic 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.By the way, the properties for application of the Cn-m-Cn were tested. It indicated that the cationic Gemini surfactants showed poor wetting ability, but their emulsifying and lime soap dispersing performance were better than traditional single-chain cationic surfactant CTAB, which were suitable for use as dispersants. The micellar aggregation number were smaller than the traditional single surfactants.