The diffusion dynamics of polymer chains within a narrow slit formed by two patch-patterned surfaces is investigated utilizing Langevin dynamics simulations. These surfaces feature periodically arranged attractive patches of size L and period d, with a staggered configuration of (0.5d, 0.5d) offsets along the x and y axes. When d is fixed, the polymer chain exhibits normal diffusion over long time scales, with the translational diffusion coefficient D_xy gradually decreasing to zero as L increases. Notably, our findings reveal four distinct diffusion modes: free-diffusion mode for L ≤ L₁, where the polymer chain is mainly in a desorption state; adsorption–desorption mode for L₁ < L ≤ L₂, involving transitions from a single-patch adsorption state to a desorption state; exchange-patch mode for L₂ < L ≤ L₃, where the polymer chain switches between a single-patch adsorption state and an upper-lower double-patch adsorption state by exchanging patches; and nondiffusion mode for L > L₃, where the polymer chain is primarily in a pinned state. Furthermore, as the patch attraction strength ε_ps increases, D_xy decreases due to an increase in the adsorption time of the polymer chain. Simultaneously, critical patch size thresholds L₁, L₂, and L₃, exhibit a decreasing trend. These observations highlight the significant influence of the confining slit and patch properties on the diffusion behavior of polymer chains.

中文翻译：

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研究由贴片图案表面形成的薄缝中的聚合物链扩散行为：贴片特性的影响


利用 Langevin 动力学仿真研究了由两个贴片图案表面形成的狭窄狭缝内聚合物链的扩散动力学。这些表面具有周期性排列的 L 大小和周期 d 的有吸引力的斑块，沿 x 轴和 y 轴具有 （0.5d， 0.5d） 偏移的交错配置。当 d 固定时，聚合物链在较长的时间尺度上表现出正常的扩散，随着 L 的增加，平移扩散系数 D_xy 逐渐降低到零。值得注意的是，我们的研究结果揭示了四种不同的扩散模式：L ≤ L₁ 的自由扩散模式，其中聚合物链主要处于解吸状态;L₁ < L ≤ L₂ 的吸附-解吸模式，涉及从单贴吸附状态到解吸状态的转变;L₂ < L ≤ L₃ 的交换补片模式，其中聚合物链通过交换补片在单补片吸附状态和上下双补片吸附状态之间切换;L %3E L₃ 为非扩散模式，其中聚合物链主要处于固定状态。此外，随着贴片吸引强度 ε_ps 的增加，由于聚合物链吸附时间的增加，D_xy 降低。同时，关键补丁大小阈值 L₁ 、 L₂ 和 L₃ 表现出下降趋势。 这些观察结果强调了限制狭缝和补丁特性对聚合物链扩散行为的显着影响。