芦丁硬脂酸酯及芦丁月桂酸酯与 硬脂酸混合单分子膜的成膜性质

采用LB膜分析仪分别研究芦丁硬脂酸酯(RS)和芦丁月桂酸酯(RL)与硬脂酸(SA)的混合膜在不同物质的量条件下的崩溃压、平均分子面积、超额吉布斯函数ΔGex、可压缩性等成膜性能及其影响因素.结果显示,两体系的崩溃压均随SA的含量分数(xSA)增大而增大.对于RS/SA膜体系,随着xA增大其分子间力由吸引过渡为排斥,xSA=0.167附近膜收缩效应最大,形成最稳定的热力学状态,膜压越小SA对膜的收缩或膨胀效应越显著.对于RL/SA膜体系,在任何xSA条件下其分子间力始终为排斥,膜呈膨胀状态,混合体系不稳定,xSA=0.5时,SA对混合膜的膨胀效应最大,体系最不稳定.RS与SA具有相同的疏水链碳数, RS/SA膜体系较RL/SA膜体系的相容性和稳定性好.

Two Component Monolayers of Amphiphilic Rutin Derivatives and Stearic Acid at Water-air Interface

The pressure-area isotherms of the two component monolayers of amphiphilic rutin derivatives and stearic acid were studied in terms of their collapse pressures, area per molecule, excess free energy and compressibility as a function of the mole fraction of the stearic acid in the monolayers xSA. Results showed that the addition of stearic acid raised the collapse pressures of both mixed monolayers. With the increase of xSA, the intermolecular forces between the two kinds of molecules in the mixed monolayers of rutin stearate ester (RS) and stearic acid (SA) turned to be the repulsive force from the attractive one. The most stable state and prominent condensation of the RS/SA mixed monolayers was observed at xSA=0.167. The repulsive intermolecular forces existed in the mixed monolayers of rutin laurate ester (RL) and stearic acid (SA) regardless of the composition. The most unstable state and prominent expansion of RC/SA mixed monolayers was observed at xSA=0.5. It was also found out that the compatibility and stability of RS/SA mixed monolayers were better than that of RL/SA mixed monolayers.