Investigation of Polymer Chain Diffusion Behavior in Thin Slits Formed by Patch-Patterned Surfaces: Influence of Patch Properties

• Published in: Langmuir 2024-12, Vol.40 (52), p.27659-27666
• Main Authors: Zhang, Hao-Nan, Wang, Guo-Ao, Qi, Hang-Kai, Yang, Qing-Hui, Luo, Meng-Bo
• Format: Article
• Language: English
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/acs.langmuir.4c04264

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 ≤ L 1, where the polymer chain is mainly in a desorption state; adsorption–desorption mode for L 1 < L ≤ L 2, involving transitions from a single-patch adsorption state to a desorption state; exchange-patch mode for L 2 < L ≤ L 3, 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 > L 3, where the polymer chain is primarily in a pinned state. Furthermore, as the patch attraction strength εps increases, D xy decreases due to an increase in the adsorption time of the polymer chain. Simultaneously, critical patch size thresholds L 1, L 2, and L 3, exhibit a decreasing trend. These observations highlight the significant influence of the confining slit and patch properties on the diffusion behavior of polymer chains.