Molecular level structure analysis of Gibbs film stabilized by interaction between mesoscopic domains

近年来，光谱技术的发展使我们能够从分子水平上分析气/液界面膜的结构。然而，液/液界面处界面膜的结构分析尚未得到很好的组织，尽管它提供了关于分子组织系统如微乳液、囊泡、生物膜、本研究旨在通过对吉布斯自由基膜的结构分析，阐明生物体系中功能与结构的关系。在三年的研究过程中，通过界面张力和同步辐射X射线反射率的测量，研究了碳氟化合物（FC）和烃（HC）醇在己烷/水界面处的吉布斯膜。取得的显著成果如下：1.界面张力研究测定了溶质正己烷溶液与水的界面张力， 关于我们 温度、压力和浓度的变化。实验数据进行了分析，在严格的界面热力学，以获得界面密度，熵和体积的吸附，吸附相图，和过剩的吸附热力学量。(1)吸附的FC醇膜表现出气态（或膨胀态）和凝聚态之间的相变。(2)FC醇与HC醇在膨胀膜中混合，而在凝聚膜中不混溶，因为FC和HC链之间的相互作用很弱。(3)FC醇与HC链阳离子表面活性剂（DTAB）的互溶是由于羟基与阳离子头基之间的强吸引作用。(4)在FC醇-DTAB混合体系中，Gibbs膜自发形成多层膜. X射线反射率研究为了确定界面张力研究中发现的Gibbs膜的结构，在Brookhaven National Laboratory（USA）的NSLS中在BL-X19 C下在固定浓度下作为温度的函数进行X射线反射率测量。结果表明：（1）FC和HC醇类在二维固态下呈密排状聚集在凝聚膜中。(2)在相变温度附近，吉布斯膜是不均匀的，凝聚相区与极低密度的气体膜共存。(3)FC醇-DTAB体系的凝聚膜的总反射率低于FC醇单体系的凝聚膜。这表明FC醇和DTAB在缩合状态下混合。(4)反射率曲线的振荡支持FC醇-DTAB体系中多层膜的形成。少

Recent development of spectroscopic technique enables us to analyze the structure of interfacial films at gas/liquid interfaces from molecular level. However, the structure analysis of interfacial films at liquid/liquid interfaces has not been well organized yet, although it gives fundamental information about the structure and property of molecular organized systems such as microemulsion, vesicles, biomembranes, and so on. This study aim at elucidating the relationship between function and structure in biological system on the basis of structure analysis of Gibbs films at liquid/liquid interfaces.During the research for three years, the Gibbs films of fluorocarbon (FC) and hydrocarbon (HC) alcohols at the hexane/water interface was examined by interfacial tension and synchrotron X-ray reflectivity measurements. The noticeable results obtained are as follows.1. Interfacial tension studyThe interfacial tensions of the hexane solution of solutes against water were measured as a function … More of temperature, pressure, and concentration. The experimental data was analyzed in terms of rigorous thermodynamics of interfaces to obtain interfacial density, entropy and volume of adsorption, phase diagram of adsorption, and excess thermodynamic quantities of adsorption.(1) The adsorbed FC alcohol films exhibit phase transition between gaseous (or expanded) and condensed states.(2) FC alcohols mix with HC alcohol in the expanded film, while are immiscible in the condensed film because of very weak mutual interaction between FC and HC chains.(3) FC alcohols become to be miscible with cationic surfactant with HC chain (DTAB) due to strong attractive interaction of hydroxyl group with cationic head group.(4) In the mixed system of FC alcohol-DTAB, Gibbs film form multilayer spontaneously.2. X-ray reflectivity studyIn order to determine the structure of Gibbs films found in the interfacial tension study, the X-ray reflectivity measurements were performed at BL-X19C in NSLS of Brookhaven National Laboratory (USA) as a function of temperature at fixed concentration. The results obtained were ;(1) FC and HC alcohols are closely packed in the condensed film like two-dimensional solid state.(2) The Gibbs films are inhomogeneous by coexisting condensed phase domains with very low density gaseous film near phase transition temperature.(3) The total reflectivity in the condensed film is lower for FC alcohol-DTAB system is lower than for the condensed films of single FC alcohol systems. This suggests the mixing of FC alcohol and DTAB in the condensed state.(4) The oscillation of reflectivity curve supports the multilayer formation in the FC alcohol-DTAB system. Less