脂肪醇聚氧乙烯醚与脂肪醇混合单分子膜的稳定性  

Stability of Mixed Monolayers with Poly(ethylene oxide) Alkyl Ether and Fatty Alcohols at the Air-water Interface

作　　者：杨红伟[1] 朱谱新[1] 阳建斌[1] 吴大诚[1] 

机构地区：[1]四川大学纺织研究所,四川成都610065

出　　处：《四川大学学报（工程科学版）》2006年第3期65-69,75,共6页Journal of Sichuan University (Engineering Science Edition)

基　　金：国家自然科学基金资助项目(50473050)

摘　　要：以脂肪醇聚氧乙烯醚(C18E20)分别与正辛醇、十二醇和十八醇组合作为非离子表面活性剂与极性有机物混合表面活性剂的模型物,采用LB膜分析仪测定了在空气-水界面上形成混合单分子膜的表面压,通过不同摩尔分数的脂肪醇与C18E20混合膜的π-A等温线,分析了混合膜在空气-水界面上的稳定性。实验结果表明,C18E20与不同脂肪醇的组合都可以提高混合膜的稳定性,表现在混合膜的表面压小于π-A曲线拐点时,液态扩张性变小,并且高于π-A曲线拐点后的曲线平台区缩短;随着脂肪醇摩尔分数的增加,或者脂肪醇链长与C18E20的疏水基链长越接近,混合膜稳定性增强。所有混合膜的π-A等温线在表面压30 mN/m附近出现拐点和平台区,表明混合膜在较高表面压下发生了相分离,而当十八醇与C18E20摩尔比为0.75∶0.25混合时,混合膜没有发生相分离,稳定性最好。Poly （ethylene oxide） alkyl ether C18E20 was in combination with each of three n - fatty alcohols （1 - octanol, n - dodecanol and n - octadecanol） respectively as a model of non-ionic surfactant and polar organic substance composites, which was spreaded onto air - water interface and formed a mixed monolayer on a Langrnuir trough. The stability of each mixed monolayer was analyzed by use of π - A isotherms at various mole fractions of the C18E20 -fatty alcohol pair. It was found that the stability of the C18E20 monolayer could be enhanced by combining with fatty alcohols, based two points. The one is the expanding degree of the monolayer decreases as the surface pressure of the mixed monolayer is under the inflexion of the π - A curve, and the other is that the plateau length of the curve decreases after the surface pressure is above the inflexion of the π - A curve. The condensability of the mixed monolayer increases with the mole ratio of fatty alcohol, or with the hydrophobic chain length of the alcohol more close to that of C18E20. For almost all of the π - A isotherms of the mixed monolayers, the inflexion and the plateau always appeared near the surface pressure 30 mN/m, which showed that a phase-separating occurs at a higher surface pressure. It was also observed that the mixed monolayer is in a favorable condition to the compatibility of the multiple surfactants, as the mole ratio of C18E20 and oetadecanoic alcohol is equal to 3 ： 1.

关 键 词：脂肪醇聚氧乙烯醚 脂肪醇 混合单分子膜 稳定性 空气-水界面 

分 类 号：O647[理学—物理化学]