β-环糊精与两性表面活性剂相互作用β

Studies on Interaction of a-Cyclodextrin with Amphoteric Surfactant

用表面张力法研究了β-环糊精与十一烷基酰胺甲酸钠(C11H23CONHCOONa,SF)两性表面活性剂在不同温度下的包结作用。结果表明:SF的表面张力值(β)及表观临界胶束浓度(cmc)加入β-CD后增加,β-CD浓度越大,γ和cmc增加越多,且SF的cmc与β-CD浓度存在线性关系,随温度的升高,两性表面活性剂的表面张力值降低,意味着它们的表面活性随温度升高而增强。利用表面张力测定了β-CD-SF体系在不同温度下的包结形成常数Ka,进而求得了包结过程的焓变和熵变,结果表明,该过程是焓和熵均有利的过程,进一步说明疏水作用是形成包结物最重要的的作用力之一。

The inclusion complexes of a-cyclodextrin(a-CD) with amphoteric surfactant s (C11H23CONHCOONa,SF) in aqueous solutions have been studied by surface tension measurement at different temperatures. The surface tension curves of the surfac tants in the presence of a-CD are higher than that in the absence of a-CD. T he curves raise higher with the increase of a-CD concentrations for surfactant . The apparent critical micelle concentration(cmc) of the surfactant varies li nearly with a-CD concentration. The Inclusion constants (Ka) of the inclusion complexes were determined by surface tension at different temperatures. Ka decre ases with the increase of temperature. In addition, the standard molar Gibbs ene rgies, enthalpies, entropies were derived for the interaction process by Ka at d ifferent temperatures. The results indicated that the association of surfactants with a-CD are favorable by both enthalpy and entropy changes, proving that hy drophobic interaction was most one of the binding forces of cyclodextrin inclusi on complex.