烷基芳基磺酸盐分子量及其分布对微乳液结构参数及热力学函数的影响

Effects of Average Molecular Mass and Its Distribution of Alkyl Aryl Sulfonate on the Structural Parameters and Thermodynamic Functions of Microemulsion

用稀释法求得了由自制的7种烷基芳基磺酸盐复配体系(AAS)/正丁醇/正癸烷/水组成的W/O型微乳液的结构参数,还求得了醇从油相转移到界面时的标准自由能,并计算出标准焓变和标准熵变。探讨了烷基芳基磺酸盐平均分子量及其分布对结构参数及热力学函数的影响。结果表明,分散相有效半径Re,内核水半径Rw,二者之差di和表面活性剂分子在每个液滴中的平均聚集数n值均呈现为正态分布<递减分布<均匀分布<递增分布<反正态分布;分散相颗粒总数Nd和分散相界面外层总面积Ad值均呈现为正态分布>递减分布>均匀分布>递增分布>反正态分布;-ΔG0o→i值呈现为正态分布(5.36 kJ/mol)<递减分布(5.49 kJ/mol)<均匀分布(5.64 kJ/mol)<递增分布(5.78 kJ/mol)<反正态分布(6.01 kJ/mol);ΔS0o→i值呈现为正态分布(26.88 J/(mol.K))<递减分布(27.12 J/(mol.K))<均匀分布(27.60 J/(mol.K))<递增分布(28.06 J/(mol.K))<反正态分布(29.23 J/(mol.K));Rw、Re、n、di、-ΔG0o→i、ΔH0o→i和ΔS0o→i值均随磺酸盐平均分子量的增大而增大;Nd、Ad值均随磺酸盐平均分子量的增大而减小;且在实验范围内,结构参数、-ΔG0o→i、ΔS0o→i与磺酸盐平均分子量均呈线性关系;后两者分别为y=0.0586x-17.916,y=0.2203x-61.275。

The structural parameters of complex systems of seven kinds of aryl sulfonate （synthesized in the laboratory ） alkyl aryl sulfonate （AAS）/n-butanol/n-decane/water microemulsions were obtained by means of a dilution method. We also calculated the standard free energy △G^0o→i of transfer from the continuous oil phase to the interracial region, the standard enthalpy △H^0o→i and the standard entropy △S^0o→ivalues. The effects of the average molecular mass and its distribution of AAS on the structural parameters and thermodynamic functions were investigated. The results show that the effective radius of dispersive phase Ro, the radius of inner sphere water Rw, their difference d1, the average aggerate number of surfactant molecules per drop n, have the tendency of normal distribution 〈 descending distribution 〈 uniform distribution 〈 incremental distribution 〈 reversed normal distribution. The total number of dispersion phase particles Nd and the total interface area of dispersion phase outer sphere Ad appear to be contrary to the above consequence. The values of - △G^0o→i exhibit the tendency of normal distribution （5.36 kJ/mol） 〈 descending distribution （5.49 kJ/mol） 〈 uniform distribution （ 5.64 kJ/mol ） 〈 incremental distribution （ 5.78 kJ/mol ） 〈 reversed normal distribution （6.01 kJ/mol）. The values of △S^0o→ihave the tendency of normal distribution （26. 88 J/（ mol·K）） 〈 descending distribution （ 27. 12 J/（ mol · K ） ） 〈 uniform distribution （ 27.60 J/（mol · K ） ） 〈 incremental distribution（28.06 J/（mol. K）） 〈 reversed normal distribution （29. 23 J/（ mol· K））. With the increase of average molecular mass, the values of Rw, Re, n, di, - △G^0o→i, △H^0o→i, △S^0o→i increase while the values of Nd, Ad decrease. In addition, the values of structural parameters, △G^0o→i and △S^0o→i change linearly with the average molecular mass of the AAS, the latter two are y = 0. 0586x - 17. 916 and y = 0. 2203x - 61. 275, respectively.