Synthesis of a series of hydroxy-sulfobetaine surfactant and their micelle formation behavior

Three hydroxy-sulfobetaine surfactants with different carbon chain length were synthesized from long chain alkyl tertiary amine and sodium 3-chloro-2-hydroxypropanesulfonate as starting materials.Their structures were characterized by elemental analysis,MS,1HNMR and FTIR.Their critical micelle concentrations(cmc) in aqueous solutions at different temperature were determined and their micelle formation behavior was studied.Results showed that when the carbon number in the hydrophobic chain increases from C8 to C14 at 25 ℃,the values of their cmc decreases from 1.32×10-2 mol·L-1 to 1.67×10-4 mol·L-1,and surface tensions under cmc(γcmc) decreases from 35.9 mN·m-1 to 34.6 mN·m-1.For a same surfactant,with the increase of temperature,the values of its cmc increases slightly,while the values of its γcmc decreases slightly.The calculation of thermodynamic parameters of micelle formation showed that the process of micelle formation is driven by the entropy.