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

Abstract

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 ε 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.