烷基羧酸钠与β-环糊精包结物稳定常数的测定

Determination of Association Constants for β-Cyclodextrin-Surfactant Inclusion Complexes

用表面张力法研究了烷基羧酸钠与β-环状糊精（β-CD）形成的包结物。实验结果表明表面张力法可以作为一种行之有效的方法确定表面活性剂与β-CD形成包结物的稳定常数。发现在表面活性剂浓度不变时，增加β-CD的浓度溶液的表面张力上升，并达到纯水的表面张力值。有β-CD存在时，表面张力-表面活性剂浓度曲线效无β-CD时为高，而且β-CD浓度越高，该曲线上升的越高。同时在实验中发现，表观cmc值与β-CD浓度有线性关系；表面活性剂键长越长，与β-CD的相互作用越强，稳定常数越大。

Inclusion complexes of β-Cyclodextrin(β-CD)with sodium carboxylate (CnH2n+1COONa, n = 7,9, 10, 11 )in aqueous solutions are studied by surface tension measurement at the air/water interface at 35 C. At given concentraSions of the surfactants,the surface tension increases with.an increase in β-CD concentration to a maximum value,at which it holds. The surface tension curves of the surfactants in the presence of β-CD are higher than those in the absence of β-CD. The curves rise higher with the increase in β-CD concentration for each surfactant. the apparent critical β-CD micelle concentra-(cmc)of the surfactants very linearly with β-CD concentration. A method based on surface tension measurements is used to determine the association constants for 1: 1 inclusion complexes. This method is very reliable and easy to perform. The results display that the longer the hydrophobic chain of the surfactant,the greater the association constants with β-CD.