脂肪酸单乙醇酰胺硫酸酯盐的物化性能

用滴体积法测定了纯化脂肪酸单乙醇酰胺硫酸酯盐(MSN)系列产品水溶液的表面张力,发现当MSN疏水基碳数(n)由10增至16时,其表面过剩浓度(Γm)由2.37×10-6mol/m2增至2.88×10-6mol/m2,临界表面张力(γCMC)由28.79 mN/m降至23.86 mN/m,降低表面张力20 mN/m所需浓度的负对数(pC20)由3.53升为5.54,临界胶束浓度(CMC)由1.40×10-3mol/L降为0.52×10-3mol/L。在所测定的温度(25℃)下,logCMC=-2.13-0.07n;在胶束化过程中,TΔS0m ic对ΔG0m ic的贡献比ΔH0m ic大,MSN胶束化的主要驱动力是熵变。

Physico-chemical Properties of Sodium Fatty Acid Monoethanolamide Sulfate

The surface tensions of a series of purified sodium fatty acid monoethanolamide sulfate(MSN) were determined by drop volume method.It was found that,with the increase of carbon number(n) in the hydrophobic group of MSN,the surface excess concentration(Γ_m) increased from 2.37×10~(-6) mol/m~(2) to 2.88×10~(-6) mol/m~(2),the critical surface tension(γ_(CMC)) decreased from 28.79 mN/m to 23.86 mN/m,the negative logarithm of the surfactant concentration in the bulk phase required to produce a 20 mN/m reduction in the surface tension of the solvent(pC_(20)) increased from 3.53 to 5.54,and the critical micelle concentration(CMC) decreased from 1.40×10~(-3) mol/L to 0.52×10~(-3) mol/L.At 25 ℃ the equation logCMC=-2.13-0.07n was defined.TΔS~0_(mic) contributes more to ΔG~0_(mic) than ΔH~0_(mic) do,so entropy change is the main drive force for the micelle formation of MSN.