氨基链修饰氧化石墨烯/环氧树脂界面性能的分子动力学模拟

Molecular Dynamics Simulation of Interfacial Properties of Amino Chain Modified Graphene Oxide/Epoxy Resin

目的对氨基链修饰氧化石墨烯与DGEBA/3,3′-DDS环氧树脂复合材料界面的形成过程和性能进行理论研究,为环氧树脂涂层的性能改性提供理论依据。方法利用Materials Studio 2019软件的Amorphous Cell模块建立了复合材料界面模型,采用分子动力学模拟方法对界面的结构、能量变化、界面处基团运动过程、界面处浓度分布和界面结合能进行计算,确立了表面氨基链修饰氧化石墨烯与环氧树脂复合材料界面的形成机制。结果复合材料界面的温度和能量经过初始模拟阶段(t<50 ps)后在小范围内震荡,体系处于动力学平衡状态。界面的形成过程经历了竖直方向的靠近运动、小范围内的震荡平衡和层间相互切向运动3个阶段,主要是氧化石墨烯表面的羧基和环氧树脂内部包含反应碳原子的分子链段之间相互作用。表面氨基链修饰氧化石墨烯浓度峰呈单一的峰,环氧树脂浓度峰含有多个峰值,界面厚度为0.82 nm。界面间的相互作用主要体现为氧化石墨烯表面官能团与环氧树脂分子间存在的范德华力,计算得界面作用能为27.596 kcal/mol。结论表面氨基链修饰氧化石墨烯表面羧基与环氧树脂间相互作用的强弱决定了界面性能的优劣,从而直接影响复合材料的力学性能。分子动力学模拟可作为环氧树脂涂层改性研究行之有效的方法,为改性增强剂的选择提供理论依据。

This paper aims to study the formation process and properties of the interface between amino chain modified graphene oxide and DGEBA/3,3′-DDS epoxy resin composite in theory and provide a theoretical basis for the property modification of epoxy resin coatings.The model of composite interface was established by Materials Studio 2019 software.The interface structure,energy change,group movement process at the interface,concentration distribution and interface binding energy were calculated by molecular dynamics simulation method.The formation mechanism of the interface between aminomodified surface GO and epoxy resin composites was determined.The simulation results show that the interface temperature and energy of the composite oscillated in a small range and the system is in a state of dynamic equilibrium after the initial simulation stage(t<50 ps).The process of interface formation experienced three stages:the vertical movement,the oscillating equilibrium in a small range and the tangential movement between the layers.The interaction was mainly between the carboxyl groups on the GO surface and the molecular fragments containing the reactive carbon atoms in the epoxy resin.The thickness of interface is 0.82 nm and the concentration peak of surface amino-modified GO showed one single peak,while the concentration peak of epoxy resin contained multiple peaks.The energy of interfacial interaction was calculated as 27.596 kcal/mol,which is mainly due to the interaction of van der Waals dispersion force between epoxy resin polymer molecules and GO surface.The quality of the interface properties was determined by the strength of the interaction between the carboxyl group on the amino group modified GO surface and the epoxy resin,which directly affects the mechanical properties of epoxy resin composite.The molecular dynamics simulation can be used as an effective method to study the modification of epoxy resin coatings,that providing a theoretical basis for the selection of modification enhancers.