Chen Yitong, Yang Zhangke, Dai Linjiale, Meng Zhaoxu
Department of Mechanical Engineering, Clemson University, Clemson, SC, 29631, USA.
Int J Mech Sci. 2025 Jul 1;297-298. doi: 10.1016/j.ijmecsci.2025.110351. Epub 2025 May 6.
Graphene oxide (GO) is a promising reinforcing nanofiller for polymer nanocomposites due to its exceptional strength and strong adhesion to polymers. Despite extensive research, the effects of GO sheet arrangement and oxidation profiles on the mechanical and viscoelastic properties of these nanocomposites remain underexplored, and the underlying deformation mechanisms have not been explicitly unveiled. In this study, we employ coarse-grained molecular dynamics simulations to investigate how distinct GO arrangements (separated vs. stacked sheets), varying interfacial interactions, and a range of oxidation profiles impact the mechanical and viscoelastic properties of GO-polymethyl methacrylate (PMMA) nanocomposites. Our findings reveal that GO sheet arrangement plays a crucial role in determining the mechanical properties of nanocomposites, with separated GO sheets typically resulting in higher elastic and shear moduli due to increased interfacial area and stronger nanoconfinement effects. Additionally, stronger interfacial interactions enhance these moduli, with oxidation degree playing a complex role by simultaneously weakening GO's intrinsic stiffness. Under shear deformation, stacked GO cases exhibit inter-sheet sliding, driven by weaker GO inter-sheet interactions and stronger GO-PMMA adhesion. The inter-sheet sliding enhances the loss modulus and loss tangent of the GO-PMMA nanocomposites, with the sliding magnitude directly correlating with the dynamic moduli. Our results indicate that polymers reinforced with stacked GO sheets can achieve superior damping capability through the activation of GO inter-sheet sliding. This makes them particularly suitable for applications requiring enhanced energy dissipation. This study highlights the pivotal role of GO arrangement in shaping the mechanical and viscoelastic behavior of polymer nanocomposites, providing valuable insights for tailored nanocomposite design.
氧化石墨烯（GO）因其卓越的强度以及与聚合物的强粘附性，是一种很有前景的用于聚合物纳米复合材料的增强纳米填料。尽管已有广泛研究，但GO片层排列和氧化程度对这些纳米复合材料的力学和粘弹性性能的影响仍未得到充分探索，其潜在的变形机制也尚未明确揭示。在本研究中，我们采用粗粒度分子动力学模拟来研究不同的GO排列方式（分离的片层与堆叠的片层）、变化的界面相互作用以及一系列氧化程度如何影响GO - 聚甲基丙烯酸甲酯（PMMA）纳米复合材料的力学和粘弹性性能。我们的研究结果表明，GO片层排列在决定纳米复合材料的力学性能方面起着关键作用，分离的GO片层通常由于界面面积增加和更强的纳米限域效应而导致更高的弹性模量和剪切模量。此外，更强的界面相互作用会提高这些模量，氧化程度则通过同时削弱GO的固有刚度而发挥复杂作用。在剪切变形下，堆叠的GO情况表现出片层间滑动，这是由较弱的GO片层间相互作用和较强的GO - PMMA粘附力驱动的。片层间滑动增强了GO - PMMA纳米复合材料的损耗模量和损耗角正切，滑动幅度与动态模量直接相关。我们的结果表明，用堆叠的GO片层增强的聚合物可以通过激活GO片层间滑动实现卓越的阻尼能力。这使得它们特别适用于需要增强能量耗散的应用。本研究突出了GO排列在塑造聚合物纳米复合材料的力学和粘弹性行为方面的关键作用，为定制纳米复合材料设计提供了有价值的见解。
