Armstrong Alexander J, Apóstolo Rui F G, McCoy Thomas M, Allen Finian J, Doutch James, Cattoz Beatrice N, Dowding Peter J, Welbourn Rebecca J L, Routh Alexander F, Camp Philip J
ISIS Neutron and Muon Source, Didcot, UK.
Institute for Energy & Environmental Flows and Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
Nanoscale. 2024 Jan 25;16(4):1952-1970. doi: 10.1039/d3nr05080g.
The self-assembly and surface adsorption of glycerol monooleate (GMO) in -dodecane are studied using a combination of experimental and molecular dynamics simulation techniques. The self-assembly of GMO to form reverse micelles, with and without added water, is studied using small-angle neutron scattering and simulations. A large-scale simulation is also used to investigate the self-assembly kinetics. GMO adsorption onto iron oxide is studied using depletion isotherms, neutron reflectometry, and simulations. The adsorbed amounts of GMO, and any added water, are determined experimentally, and the structures of the adsorbed films are investigated using reflectometry. Detailed fitting and analysis of the reflectometry measurements are presented, taking into account various factors such as surface roughness, and the presence of impurities. The reflectometry measurements are complemented by molecular dynamics simulations, and good consistency between both approaches is demonstrated by direct comparison of measured and simulated reflectivity and scattering length density profiles. The results of this analysis are that in dry systems, GMO adsorbs as self-assembled reverse micelles with some molecules adsorbing directly to the surface through the polar head groups, while in wet systems, the GMO is adsorbed onto a thin layer of water. Only at high surface coverage is some water trapped inside a reverse-micelle structure; at lower surface coverages, the GMO molecules associate primarily with the water layer, rather than self-assemble.
采用实验和分子动力学模拟技术相结合的方法，研究了单油酸甘油酯（GMO）在正十二烷中的自组装和表面吸附。利用小角中子散射和模拟研究了添加和不添加水时GMO形成反胶束的自组装过程。还使用大规模模拟来研究自组装动力学。利用耗竭等温线、中子反射率和模拟研究了GMO在氧化铁上的吸附。通过实验测定GMO以及任何添加水的吸附量，并利用反射率研究吸附膜的结构。考虑到表面粗糙度和杂质的存在等各种因素，对反射率测量进行了详细的拟合和分析。反射率测量由分子动力学模拟补充，通过直接比较测量和模拟的反射率及散射长度密度分布，证明了两种方法之间的良好一致性。该分析结果表明，在干燥体系中，GMO以自组装反胶束的形式吸附，一些分子通过极性头基团直接吸附到表面，而在潮湿体系中，GMO吸附在一层薄水上。只有在高表面覆盖率下，才有一些水被困在反胶束结构内；在较低表面覆盖率下，GMO分子主要与水层缔合，而不是自组装。
