| In this paper,Octanoyl-6-O-ascorbic acid was synthesized by esterification with L-ascorbic acid and n-octanoic acid,and its purity was characterized by 1H NMR.Based on Octanoyl-6-O-ascorbic acid,the complex system with other surfactants was studied.First,Octanoyl-6-O-ascorbic acid and zwitterionic surfactant dodecyldimethyl amine oxide in water with different molar ratio compound,the micellization of mixed system was studied.The critical micelle concentration at 25 ℃ was measured by the drop volume method for different molar ratios of complex system.The results were verified by conductivity method and fluorescence method.The results show that the experimental data obtained are credible.The experimental data show that with the increase of dodecyl dimethyl amine oxide in the complex system,the critical micelle concentration of the solution first decreases and reaches a minimum at a molar ratio of 5:5 and then increases.This is because the closer the ratio of the Octanoyl-6-O-ascorbic acid to the dodecyldimethylamine oxide is,the greater interaction force between the anion and the cation in the solution and the hydrophobicity are greater,and the easier the micelle is formed.When the molar ratio of Octanoyl-6-O-ascorbic acid or dodecyldimethylamine oxide is increased,the mutual repulsive force between the same ions in the solution increases,and the micelle is hard to form.The interaction parameters can be calculated according to the slope of the line before and after the critical micelle concentration in the conductivity curve.The thermodynamic parameters △Gm0,△Hm0,△Sm0 can be obtained by the interaction parameters.The results show that the formation of mixed micelles spontaneously,and the process is exothermic.Through the system of turbidity,particle size and cryo-TEM test,the results show that the Octanoyl-6-O-ascorbic acid and lauryldimethyl amine oxide complex system at a certain molar ratio of vesicular formation.Turbidity measurements showed that,at the same concentration,the solution of the mixed system with the molar ratio of dodecyldimethyl amine oxide increases,the solution first increased turbidity,the maximum molar ratio of 5:5,and then reduced.The solution at a molar ratio of 5:5 and 6:4 was blue at a concentration of 2mM and the formation of vesicles in the solution was confirmed by dynamic light scattering and cryo-electron microscopy.At concentrations greater than 10 mM,vesicles formed in a mixed solution with a molar ratio of 7:3 and 8:2,and the larger the vesicle diameter,the greater the concentration.In this paper,the complex system of cationic surfactant 1-dodecyl-3-methylimidazolium bromide and Octanoyl-6-O-ascorbic acid at molar ratio of 7:3,8:2,9:1 was also studied.The critical micelle concentration of 1-dodecyl-3-methylimidazolium bromide/Octanoyl-6-O-ascorbic acid molar ratios was measured by conductivity method.The experimental data were verified by pH and fluorescence.Prove the accuracy of the data.The experimental results show that the critical micelle concentration of the mixed system increases with the increase of molar ratio.By studying the thermodynamics of the mixed micelles,the micellarization of the mixed system is spontaneous.Through the measurement of turbidity,it was found that the mixed solution with the molar ratio of 7:3 and 8:2,with the increase of concentration,the solution from the clarification becomes cloudy,a precipitate,and then become clear again.But when molar ratio is 9:1,the solution is always clear.Then using the dynamic light scattering measurement of three different particle size at different concentrations.The results showed that in the mixed solution with molar ratio of 7:3 and 8:2,there are larger aggregates within a certain concentration range.However,the particle size of the mixed solution with a molar ratio of 9:1 did not change as the concentration increased. |
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