A Novel Alkyl Sulphobetaine Gemini Surfactant Based on S-triazine: Synthesis and Properties

A series of alkyl sulphobetaine Gemini surfactants C n -GSBS ( n  = 8, 10, 12, 14, 16) was synthesized, using aliphatic amine, cyanuric chloride, ethylenediamine, N , N ′-dimethyl-1,3-propyldiamine and sodium 2-chloroethane sulfonate as main raw materials. The chemical structures were confirmed by FT-IR, 1 H NMR and elemental analysis. The Krafft points differ markedly with different carbon chain length, for C 8 -GSBS, C 10 -GSBS and C 12 -GSBS are considered to be below 0 °C and C 14 -GSBS, C 16 -GSBS are higher than 0 °C but lower than room temperature. Surface-active properties were studied by surface tension and electrical conductivity. Critical micelle concentrations were much lower than dodecyl sulphobetaine (BS-12) and decreased with increasing length of the carbon chain from 8 to 16, and can reach a minimum as low as 5 × 10 −5  mol L −1 for C 16 -GSBS. Effects of carbon chain length and concentration of C n -GSBS on crude oil emulsion stability were also investigated and discussed.