Synthesis And Properties Of Gemini Quaternary Ammonium Salt Surfactants With Ester Group Or Hydroxyl

Gemini surfactants could offer superior performance than the traditional corresponding surfactants, and as a reslut, their application fields have been extended, and related theories have attracted much attention. Bisquaternaryammoium salt gemini surfactant with ester bond, a new type of cationic surfactants, exhibits both high surface activities of the conventional surfactants and degradation of the esterquats. It is a kind of environmentally-friendly surfactant and has broad market prospects because of the increasingly strict requirements of environmental protection standard nowadays.Introducing hydroxyl into traditional gemini surfactants could effectively enhance its aggregation ability, promote the viscoelastic wormlike micellar systems growth and enhance the system’s viscoelasticity. Current, the objects of research on gemini surfactant containing ester group and hydroxyl are mainly single or few structure sufactants, which is against the research in the effect of hydrophobic chains and spacer group on properties and application.In this situation, this articlev designed synthesizeGemini quaternary ammonium salt surfactants with eater group(n-2-n, n-6-n, n = 10, 12, 14, 16 and 18) and hydroxyl(n-3(OH)-n, n = 10, 12, 14, 16 and 18), these fifteen products were characterized by 1H NMR. Surface activity, adsorption and aggregation behaviors of these cationic gemini surfactants were investigated by methods of measuring equilibrium surface tension, dynamic surface tension and transmission electron microscope(TEM). Moreover, the interaction between Gemini surfactant and DNA were investigated by methods of using UV- vis and fluorometric spectrophotometry, interaction between Gemini surfactant and BSA were investigated by methods of fluorometric spectrophotometry, and the effect of length of hydrophobic chains and spacer group on the interaction was discussed.The CMC values of the fifteen gemini surfactants showed a decrease with increasing length of hydrophobic chains, meanwhile, the CMC values reduced to half when every two carbon atoms increased in hydrophobic chains, while it reduced to half only when one carbon atom increased in traditional ionic surfactants. As for Gemini surfactants with eater group, the CMC values of surfactants with longer spacer group is smaller when length of hydrophobic chains is the same. However, length of hydrophobic chains has little influence onγCMC, Γmax and Amin as they have no obvious variety regulation. In addition, experiments found that the concentrated 16-3(OH)-16, 18-3(OH)-18 aqueous solutions was in colloid state, the morphology of aggregates was visualized through TEM, and vesicles were found existing in the solutions.Surface tension of these concentrated solution was dropping dramatically during the initial time and then trended to equilibrium, furthermore, the greater the density was, the greater the surface tension declined, the faster the surface tension would reach equilibrium. The adsorption process is controlled by a diffusion step at low surfactant concentration and by a mixed kinetic-diffusion adsorption mechanism at high surfactant concentration.The absorption peak of DNA was not red shifted when Gemini surfactants were added, but suefactants had hyperchromic effect to DNA.The fluorescence spectrum of the BSAwas quenched by surfactants, and the mechanism of action was a static quenching process. The binding constant of static quenching theory model indicated that, binding constant between Gemini surfactants with hydroxyl is bigger than with ester group when the length of hydrophobic chains is shorter; while the binding constant between Gemini surfactants with ester group is bigger when the length of hydrophobic chains is longer. As for Gemini surfactants with ester group, when length of hydrophobic chains is shorter, the binding constant increase with the longth of spacer group, while length of hydrophobic chains became longer, the contrary happens.The binding power between Gemini surfactants and BSA is hydrophobic effect. What’s more, higher concentration, longer hydrophobic chains and spacer groupcontributed to fluorescence intensity decreased more significantly.