Transport of a comb-like polymer across a nanochannel subject to a pulling force

We investigate the dynamics of comb-like polymer translocation through a nanochannel using three-dimensional Langevin dynamics simulations based on a coarse-grained chain model. A comprehensive set of simulations are performed to examine the effects of system parameters such as the grafting density ρ of the side chains, the polymer chain length, the nanochannel dimensions, and the magnitude of the pulling force on the translocation dynamics. For a given polymer chain length, keeping the backbone length is constant while varying ρ, we have found that the dependence of the mean translocation time τ on ρ is non-monotonic, with a maximum translocation time for a specific ρ at which the translocation is the slowest. The simulation results also show that τ is not significantly affected by the channel width above a certain radius, while the comb-like polymer translocation is hindered by a narrower channel due to increased interactions between the chain monomers and the channel. In addition, τ increases linearly with the nanochannel length. A linear scaling relationship between the mean translocation time τ and the chain length N of polymer is obtained, τ ~ N. Similarly, the dependence of τ on the backbone chain size Nbb has a quasi-linear dependence, τ ~ Nbb. On the other hand, the translocation velocity v follows a power-law relationship with the polymer chain length N as v ~ N⁻¹. The mean translocation time also shows an inverse linear relationship with the magnitude of the pulling force F, τ ~ F⁻¹. The power-law relationships discovered in this study contribute to the fundamental understanding of the comb polymer translocation dynamics and to establishing a framework for further investigations in this field.