寡聚乙二醇自组装单分子膜表面摩擦的分子模拟研究

发布时间：2018-04-28 07:45

本文选题：聚乙二醇 + 摩擦　；参考：《浙江大学》2017年硕士论文

【摘要】：聚乙二醇是一种典型的亲水抗污材料,具有优良的抗蛋白质吸附性能。不仅如此,聚乙二醇在水环境中还表现出的低摩擦特性。相关研究表明,这一低摩擦特性可能与其表面的水合层密切相关。由于实验手段的局限性,目前尚难以直接在微观尺度上阐释聚乙二醇在水中的低摩擦机理。近年来,分子模拟已愈来愈成为一种不可或缺的考察微观分子相互作用机理的有效手段。本文将采用全原子分子动力学模拟,以寡聚乙二醇自组装单分子膜为研究对象,从聚乙二醇的水合层中分子的结构和动态行为分析该材料的摩擦机制和特征。此外,本文也考察了电场中水分子的结构及动态响应特征,以期为未来进一步研究电控摩擦过程提供铺垫。全文主要内容和结论有:1、模拟了不同间距的寡聚乙二醇自组装单分子膜(OEG-SAM)表面的水润滑摩擦。结果分析表明,OEG-SAM表面在摩擦过程中显著影响了表面上水合层中水分子的动态行为,水合层的水的结构和动态行为与主体水存在差异。表面摩擦系数与水合层的相互作用关系密切。当表面间距低于15A时,两表面的水合层直接接触,摩擦系数较高。2、模拟了不同温度下的寡聚乙二醇自组装单分子膜(OEG-SAM)表面的水润滑摩擦。对表面水合层的分析表明,温度280K-310K范围内,升高温度会导致水合层内水分子动态行为的增强,水合层的流动性增强,进而导致表面摩擦系数的降低。3、模拟了水在电场中的行为。结果表明:外加电场的升高会导致水的密度上升。与未加电场相比,外加电场强度为1.0V/A时,水的密度上升22%。当外加电场为周期性电场时,水的密度也会以相同的周期实时变化。
[Abstract]:Polyethylene glycol (PEG) is a typical hydrophilic antifouling material with excellent protein adsorption resistance. Not only that, polyethylene glycol in the water environment also showed a low friction characteristics. The results show that this low friction property may be closely related to the hydration layer on the surface. Due to the limitation of experimental means, it is difficult to explain the mechanism of low friction of polyethylene glycol in water directly on micro scale. In recent years, molecular simulation has become an indispensable and effective means to study the mechanism of micromolecular interaction. The friction mechanism and characteristics of polyethylene glycol (PEG) self-assembled monolayer films are analyzed from the molecular structure and dynamic behavior in the hydration layer of polyethylene glycol by means of full atomic molecular dynamics simulation. In addition, the structure and dynamic response of water molecules in an electric field are also investigated in order to provide a basis for further study on the electronic friction process in the future. The main contents and conclusions of this paper are as follows: 1. The water lubricated friction on the surface of monolayer OEG-SAM with different spacing is simulated. The results show that the surface of OEG-SAM has a significant effect on the dynamic behavior of water molecules in the hydrated layer during friction, and the water structure and dynamic behavior of the hydrated layer are different from that of the main water. The surface friction coefficient is closely related to the interaction of the hydrated layer. When the surface spacing is lower than 15A, the hydration layer of the two surfaces is in direct contact with a high friction coefficient of 0.2. The water lubricated friction on the surface of the monolayer OEG-SAM is simulated at different temperatures. The analysis of the surface hydration layer shows that in the range of temperature 280K-310K, increasing the temperature will lead to the enhancement of the dynamic behavior of water molecules in the hydration layer and the increase of the fluidity of the hydration layer, which will lead to the decrease of the friction coefficient of the surface. The behavior of water in the electric field is simulated. The results show that the density of water increases with the increase of external electric field. When the applied electric field intensity is 1.0V/A, the water density increases 22% compared with that without electric field. When the applied electric field is a periodic electric field, the density of water will change in real time with the same period.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O632.3

【参考文献】