Cui Jianzheng, Zeng Fanlin, Wei Dahai, Wang Youshan
Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
National Key Laboratory of Science and Technology on Advanced Composites in Special Environment, Center for Composite Materials, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
J Phys Chem B. 2025 Mar 6;129(9):2607-2620. doi: 10.1021/acs.jpcb.4c07630. Epub 2025 Feb 24.
Understanding the interfacial mechanical behavior of graphene-polymer nanocomposites is of great significance to achieve a balance between high strength and high toughness. Grafting polymer chains onto the surface of graphene can effectively improve the dispersibility of graphene in the polymer matrix and alter the interfacial mechanical properties between graphene and the polymer matrix. In this work, we conduct coarse-grained molecular dynamics simulations to systematically study the interfacial mechanical properties between the polymer-grafted graphene and the polymer matrix. By performing normal and shear separation tests, the influences of separation velocity, graft chain length, grafting density, and matrix cross-linking density on the interfacial mechanical properties are comprehensively investigated. Results indicate that compared with pristine graphene, grafting polymer chains onto the surface of graphene can significantly enhance the fracture toughness of the graphene-polymer interface system at the expense of weakening strength. The use of medium-length graft chains and low grafting density helps to find a balance between high strength and high toughness, achieving optimal design of high-performance nanocomposites. In addition, during high-velocity separation, an increase in matrix cross-linking density is beneficial to improve the interfacial cohesive and shear strength but has no significant effect on interfacial fracture toughness. This study sheds new light on the interface design of graphene-polymer nanocomposites with desired performance.
了解石墨烯-聚合物纳米复合材料的界面力学行为对于在高强度和高韧性之间实现平衡具有重要意义。将聚合物链接枝到石墨烯表面可以有效提高石墨烯在聚合物基体中的分散性，并改变石墨烯与聚合物基体之间的界面力学性能。在这项工作中，我们进行了粗粒度分子动力学模拟，以系统地研究聚合物接枝石墨烯与聚合物基体之间的界面力学性能。通过进行法向和剪切分离测试，全面研究了分离速度、接枝链长度、接枝密度和基体交联密度对界面力学性能的影响。结果表明，与原始石墨烯相比，在石墨烯表面接枝聚合物链可以显著提高石墨烯-聚合物界面体系的断裂韧性，但会以降低强度为代价。使用中等长度的接枝链和低接枝密度有助于在高强度和高韧性之间找到平衡，实现高性能纳米复合材料的优化设计。此外，在高速分离过程中，基体交联密度的增加有利于提高界面内聚强度和剪切强度，但对界面断裂韧性没有显著影响。这项研究为具有所需性能的石墨烯-聚合物纳米复合材料的界面设计提供了新的思路。
