Synthesis and Characterisation of Sulfonated Dimeric Malenised Soya Fatty Acid : A Novel Gemini Surfactant

Gemini surfactants are a new type of surfactants that possess two hydrophilic heads and two hydrophobic tails bonded through a spacer group. The synthesis of a novel gemini surfactant was carried out in three stages in the present research. Initially soya fatty acid was malenised using maleic anhydride at higher temperature to avoid Diels Alder adduct, followed by the esterification with 1,4 butanediol to form the dimer. The dimer was sulfonated using sodium bisulfite. The new compound was characterised by chemical analyses, FT-IR spectra, 1 H NMR and supported by LCMS. Spectral data provide strong evidence for the formation of the gemini surfactant. The surfactant properties such as surface tension, critical micelle concentration, foam stability and contact angle were measured. Gemini surfactant was superior in surface active properties to the monomeric surfactant with one hydrophilic head and one hydrophobic tail. In particular, gemini surfactant had remarkably low critical micelle concentration.