State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania.
Langmuir. 2012 Mar 20;28(11):5116-24. doi: 10.1021/la2051542. Epub 2012 Mar 6.
We investigate the mechanism of self-assembly of fatty acids (FA) and methyl oleate on an Al oxy-hydroxide surface with a view to deciphering the role and nature of interfacial processes (adsorption, chemical binding, molecular organization, etc.). For this purpose, we focus on parameters related to intrinsic properties of molecules, namely the level of unsaturation and the nature of the head group (carboxylic acid or ester). After the FA adsorption, the presence of coordinative bonded carboxylate species on the Al oxy-hydroxide surface is demonstrated by means of PM-IRRAS analysis. We observe that contact of methyl oleate with the surface leads to its chemical transformation through a saponification reaction. As a consequence, it binds to the surface in a manner similar to that for fatty acids. Through an innovative mode of atomic force microscopy (AFM), the organization of the adsorbed molecules is demonstrated. Our results reveal the existence of highly ordered nanostructures guided by the FA self-assembly. The size of these nanostructures was determined with accuracy, suggesting that it exceeds one FA monolayer. By contrast, no organization was observed with methyl oleate.
我们研究了脂肪酸（FA）和油酸甲酯在氧化铝水合物表面自组装的机制，旨在阐明界面过程（吸附、化学结合、分子组织等）的作用和性质。为此，我们关注与分子固有特性相关的参数，即不饱和程度和头基的性质（羧酸或酯）。FA 吸附后，通过 PM-IRRAS 分析证明了 Al 氧氢氧化物表面上存在配位键合的羧酸盐。我们观察到，油酸甲酯与表面接触会导致其通过皂化反应发生化学转化。因此，它以类似于脂肪酸的方式与表面结合。通过一种创新的原子力显微镜（AFM）模式，证明了吸附分子的组织。我们的结果表明，FA 自组装指导下存在高度有序的纳米结构。这些纳米结构的大小确定得非常准确，表明其超过一个 FA 单层。相比之下，用油酸甲酯则没有观察到组织。
