基于系综的分子动力学模拟研究水合环氧-石墨烯纳米复合材料的热弹性质
Thermo-elastic properties of hydrated epoxy-graphene nanocomposites from ensemble-based molecular dynamics simulations
AI总结：
研究通过大系综分子动力学模拟，探究水合对环氧-石墨烯纳米复合材料玻璃化转变和弹性力学性能的影响，发现水含量3%wt是阈值，低于此值力学性能不受影响，超过则恶化，强调系综大小对预测可靠性的关键作用，为材料设计提供指导。
AI中文摘要：
环氧基材料具有吸湿性，会显著改变其性能。石墨烯被视为减轻水合对基体不利影响的潜在材料。本研究通过大系综分子动力学模拟，研究了水合对环氧树脂及其石墨烯纳米复合材料玻璃化转变和弹性力学性能的影响，关注水含量高达5%wt的情况。结果显示，水含量3%wt是一个阈值，低于此值，水合主要降低玻璃化转变温度，力学性能不受影响；超过此值，力学性能恶化。研究还强调了系综大小对确保此类异质系统分子动力学预测可靠性的关键作用。这些发现为环氧基材料的水合行为提供了新见解，强调了石墨烯增强其耐环境性并推进了对聚合物纳米复合材料结构-性能关系的理解。
英文摘要：
Epoxy-based materials are inherently hygroscopic, absorbing moisture from the environment, which can significantly alter their short and long-term performance. The presence of graphene is often considered as a potential candidate to act as a microscopic barrier, mitigating the adverse effects of hydration on the matrix. This study investigates the impact of hydration on the glass transition and elastic mechanical properties of epoxy resins and their graphene nanocomposites, focusing on water content up to 5 %wt. Using large-ensemble molecular dynamics simulations, we analyze the temperature-driven glass transition and mechanical response of both neat epoxy and epoxy-graphene systems under varying hydration levels. Our results reveal a distinct threshold at 3 %wt water content: below this, hydration primarily reduces the glass transition temperature, while mechanical properties remain unaffected. Beyond 3 %wt, however, the mechanical properties deteriorate, highlighting a non-linear sensitivity to water uptake. Furthermore, we emphasize the critical role of ensemble size in ensuring the reliability of molecular dynamics predictions for such heterogeneous systems. Our simulations demonstrate that ensembles substantially larger than current state-of-the-art standards are necessary to achieve converged distributions of the predicted mechanical properties, particularly in highly heterogeneous hydrated epoxy-graphene nanocomposites. These findings provide novel insights into the hydration behavior of epoxy-based materials and underscore the potential of graphene to enhance their environmental resistance. This work also advances the understanding of structure-property relationships in polymer nanocomposites, offering guidance for the design of more robust materials in humid environments.
