Abnormal polymer transport in crowded attractive micropost arrays

W Chien and YL Chen, SOFT MATTER, 12, 7969-7976 (2016).

DOI: 10.1039/c6sm01488g

We investigate polymer diffusion in a quasi-two-dimensional environment decorated with attractive cylindrical posts using Langevin dynamics simulation. We find that the polymer diffusivity has non-monotonic dependence on the post array density. This diffusive behavior strongly depends on the adsorption-desorption transition and the critical adsorption strength epsilon(c). For epsilon < epsilon(c), the polymer undergoes normal diffusion and the diffusivity decreases as the post density increases due to the reduction of the void volume. For epsilon > epsilon(c), polymer dynamics is strongly mediated by post adsorption, and we observe a regime where the polymer diffusivity increases as the post density increases. The polymer diffusivity reaches a maximum, which can be attributed to cross-post translation enabled by large polymer conformation fluctuations. We find both cross-post transport and polymer conformation fluctuations strongly depend on the post absorption strength and the chain length.

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