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Published March 28, 2023 | public
Journal Article

Behaviors of a Polymer Chain in Channels: From Zimm to Rouse Dynamics


The effects of confinement and hydrodynamic interactions on single-chain diffusion behaviors are studied by using a combination of molecular dynamics and multiparticle collision dynamics simulations. For polymers in free space, the simulation results showed that the diffusion coefficient D∞ for long chains scales with the chain length N as D_∞ ∼ N^(–ν) (ν = 0.588), consistent with the Zimm dynamics, but it deviates from the Zimm dynamics for short chains. For polymers confined in channels with width H, the diffusion coefficient is found to follow two different scaling relations. The observed behaviors could be understood by introducing a microscopic hydrodynamic length ξₕ, below which the overall effect of hydrodynamic interactions becomes less important. For a confined chain, the diffusion behavior exhibits a crossover from Zimm (nondraining) to Rouse (free draining) dynamics as the channel size H decreases. When H is larger than ξₕ, the confinement experienced by the polymer chain is weak and the diffusion coefficient scales as D ∼ H^(0.7), in accordance with the prediction of blob theory; when H is smaller than ξₕ, D becomes independent of H, implying a free draining condition. A general analytical expression of D is derived by extending the partially permeable sphere model to the blob scale, which gives a quantitative description of the transition from Zimm to Rouse dynamics as H decreases.

Additional Information

© 2023 American Chemical Society. This work was supported by the National Key R&D Program of China (grant no. 2020YFA0713601), the National Natural Science Foundation of China (grant nos. 21790340 and 22073092), and the Key Research Program of Frontier Sciences, CAS (grant no. QYZDY-SSW-SLH027). Additional support for Y.L. was provided by the Youth Innovation Promotion Association of CAS (grant no. Y202054). We thank the anonymous reviewers, whose constructive comments have helped improve the presentation of our work. The authors declare no competing financial interest.

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August 22, 2023
October 18, 2023