Department of Optometry, School of Optics and Optometry, University of Santiago de Compostela, Campus Sur., 15706-Santiago de Compostela, Spain.
J Phys Chem B. 2010 Mar 4;114(8):2695-703. doi: 10.1021/jp907900g.
Mixed monolayers of poly(methyl metacrylate) (PMMA) and monopalmitin (Mp) were used for the study of their interactions. A thorough analysis of surface pressure (pi)-area (A) isotherms with the Langmuir monolayer technique, complemented with Brewster angle microscopy (BAM) images was performed. Mixed films show two phase transitions at a surface pressure of 14.5 mN/m and at 20-21 mN/m, respectively. Moreover, mixed monolayers show two well-defined collapses: one, corresponding to the lipid (at surface pressures of 50-51 mN/m) and the another one, ascribed to the PMMA, at surface pressure values of 57-58 mN/m. When the mean molecular areas of the mixed films (A(1,2)) were plotted versus film composition (X(1) or X(2)), positive deviations from the ideal behavior were observed at surface pressures below 15 mN/m, which were mainly attributed to a change in the conformation of the PMMA molecules at the surface. However, at higher surface pressures, the areas per monomer unit of the mixed monolayers obey the additivity rule, attributed to the fact that the film components form an immiscible system in these conditions.
混合单层的聚甲基丙烯酸甲酯（PMMA）和单棕榈酸甘油酯（Mp）用于研究它们的相互作用。使用 Langmuir 单层技术对表面压力（pi）-面积（A）等温线进行了彻底分析，并辅以布鲁斯特角显微镜（BAM）图像。混合膜在表面压力为 14.5 mN/m 和 20-21 mN/m 时分别显示出两个相转变。此外，混合单层显示出两个明确定义的崩塌：一个对应于脂质（在表面压力为 50-51 mN/m 时），另一个归因于 PMMA，在表面压力值为 57-58 mN/m 时。当混合膜的平均分子面积（A（1,2））相对于膜组成（X（1）或 X（2））绘制时，在低于 15 mN/m 的表面压力下观察到理想行为的正偏差，这主要归因于 PMMA 分子在表面的构象变化。然而，在较高的表面压力下，混合单层的每个单体单元的面积遵循加和规则，这归因于在这些条件下膜成分形成不混溶系统的事实。
