氧化石墨烯复合水泥基材料的分子动力学模拟

Molecular dynamics simulation of graphene oxide composite cement-based materials

氧化石墨烯(GO)边缘的大量含氧官能团具有更好的反应活性,能够有效的增强水泥基材料的性能。本文为探究氧化石墨烯中各含氧官能团对水泥基材料性能的影响,建立了GO/C-S-H、GO羧基/C-S-H、GO羟基/C-S-H和GO环氧基/C-S-H模型。采用分子动力学的方法对复合材料的力学参数、界面吸附能、动力学特性进行研究。结果表明:GO的加入使复合材料的杨氏模量提高了10.7%,泊松比提高了12%。GO中的环氧基有助于复合材料界面的稳定性,羟基有助于复合材料内部原子间作用更紧密。含氧官能团与钙原子间的钙氧键是粘聚力的来源之一,钙氧键键长的顺序为Ca-OH<Ca-O<Ca-COOH,GO中羟基与钙原子间的作用力是粘聚力的主要来源。羟基和羧基能够增加水和钙原子的传质速度,有利于水化反应的进行。

The abundant oxygen-containing functional groups at the edges of graphene oxide(GO)have better reactivity and can effectively enhance the performance of cement-based materials.This article investigates the influence of various oxygen-containing functional groups in graphene oxide on the properties of cement-based materials,and establishes GO/C-S-H,GO carboxyl/C-S-H,GO hydroxyl/C-S-H,and GO epoxy/C-S-H models.Using molecular dynamics methods to study the mechanical parameters,interfacial adsorption energy,and dynamic characteristics of composite materials.The results showed that the addition of GO increased the Young's modulus of the composite material by 10.7%and the Poisson's ratio by 12%.The epoxy group in GO contributes to the stability of the composite material interface,while the hydroxyl group contributes to a tighter interatomic interaction within the composite material.The calcium oxygen bond between oxygen-containing functional groups and calcium atoms is one of the sources of cohesion.The order of calcium oxygen bond lengths is Ca-OH<Ca-O<Ca-COOH,and the interaction force between hydroxyl groups and calcium atoms in GO is the main source of cohesion.Hydroxyl and carboxyl groups can increase the mass transfer rate of water and calcium atoms,which is beneficial for the hydration reaction.