高等学校化学学报

高等学校化学学报

• 研究论文 • 上一篇    

准二维受限体系中高分子链的动力学研究

谢冲墨1,2，卢宇源1，安立佳1，王振华1，王健3，李明伦1   

  1. 1. 中国科学院长春应用化学研究所高分子科学与技术全国重点实验室 2. 中国科学技术大学应用化学与工程学院 3. 沧州师范学院化学与化工学院
  • 收稿日期:2025-09-05 修回日期:2025-10-15 网络首发:2025-10-15 发布日期:2025-10-15
  • 通讯作者: 王振华 E-mail:zhwang@ciac.ac.cn
  • 基金资助:
    国家自然科学基金（批准号：22341304，22303100），国家重点研发计划（批准号：2020YFA0713601，2023YFA1008800）资助

Study on the Dynamics of Polymer Chains in Quasi-two-dimensional Confined Systems

XIE Chongmo1,2, LU Yuyuan1, AN Lijia1, WANG Zhenhua1, WANG Jian3, LI Minglun1   

  1. 1. State Key Laboratory of Polymer Science and Technology,Changchun Institute of Applied Chemistry, Chinese Academy of Sciences 2. University of Science and Technology of China 3. College of Chemistry and Chemical Engineering,Cangzhou Normal University
  • Received:2025-09-05 Revised:2025-10-15 Online First:2025-10-15 Published:2025-10-15
  • Contact: WANG Zhenhua E-mail:zhwang@ciac.ac.cn
  • Supported by:
    Supported by the National Natural Science Foundation of China(Nos.22341304 and 22303100), the National Key R&D Program of China (Nos.2020YFA0713601 and 2023YFA1008800)

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摘要： 拓扑约束对高分子链动力学行为的影响是凝聚态物理与软物质科学领域的核心科学问题之一。本文通过构建具有规则/无规拓扑结构及刚性/柔性拓扑约束的准二维受限模型，结合分子动力学模拟方法，系统探究了拓扑约束的静态几何特征(间距、有序性)与动态涨落(柔性链阵列)对高分子链平衡态构象及非平衡态动力学行为的调控规律。研究结果表明：在规则刚性点阵约束下，测试链的扩散系数(D)与松弛时间(t_R)和链长(N)之间满足经典标度关系D ～ N^?1.5和t_R ～ N^3，其静态尺寸与点阵间距无关，与理论预测高度吻合；在小间距条件下，无规刚性点阵中的高分子链动力学行为与规则点阵体系几乎等效，表明平衡态拓扑涨落未显著改变有效约束管径的均匀性，这一发现修正了Muthukumar随机介质模型的预期；柔性链阵列的动态涨落(如构象重排)可引发“动态约束增强效应”：测试链的短时内部运动与长时整体扩散发生解耦，其整链松弛时间较刚性约束体系提升约3倍，其本质源于拓扑摩擦的额外贡献；在恒速拉伸过程中，测试链受力呈现显著“过冲”现象，且整链摩擦系数随拉伸速率非线性增加，直接证实了拓扑摩擦对高分子链非线性力学响应的核心作用。本研究为深入理解复杂受限体系的动力学规律及指导高分子材料动态性能优化提供了理论依据。

关键词: 准二维受限体系, 拓扑约束, 分子动力学, 拓扑摩擦, 管子模型

Abstract: The influence of topological constraints on the dynamic behavior of polymer chains constitutes a core scientific challenge in condensed matter physics and soft matter science. Herein, we employed molecular dynamics simulations to systematically investigate how static geometric features and dynamic flexibility of topological constraints regulate the equilibrium conformations and non-equilibrium dynamics of polymer chains within quasi-two-dimensional confinement models, encompassing both regular/disordered topological structures and rigid/flexible topological constraints. Under regular rigid lattice confinement, the diffusion coefficient D and relaxation time t_R vs the chain length N of the test chain adhere to the classical scaling relationships D ～ N^?1.5 and t_R～ N^3 with static dimensions independent of the lattice spacing—a result in excellent agreement with theoretical predictions. For small spacing regimes, the dynamic behavior of polymer chains in disordered rigid lattices is nearly equivalent to that in regular lattice systems, indicating that equilibrium topological fluctuations do not significantly alter the uniformity of the effective confinement tube diameter. This finding revises the expectations of Muthukumar's random medium model. Conformational rearrangements of flexible chains induce a "dynamic constraint enhancement effect": short-time internal motions and long-time overall diffusion of the test chain become decoupled, with the whole-chain relaxation time increasing by approximately 3-fold compared to rigid constraint systems. This effect arises from the additional contribution of topological friction. During constant-velocity stretching, the force on the test chain exhibits a significant overshoot phenomenon, and the whole-chain friction coefficient increases nonlinearly with stretching rate, directly confirming the critical role of topological friction in the nonlinear mechanical response of polymer chains. This work offers insights to deepen the understanding of dynamic laws in complex confined systems and may guide the optimization of polymer material dynamic properties.

Key words: Quasi-two-dimensional confined system, Topological constraint, Molecular dynamics; Topological friction, Tube model

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