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

HN Zhang and GA Wang and HK Qi and QH Yang and MB Luo, LANGMUIR, 40, 27659-27666 (2024).

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 epsilon(ps) 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.

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