Translocation of a comb-like polymer out of a confined nanochannel driven by an external pulling force

We employ three-dimensional Langevin Dynamics simulations to investigate the end-pulled translocation of a comb-like homopolymer through a nanopore, starting from a closed nanochannel. This investigation examines how factors such as confinement dimensions, nanopore sizes, polymer architecture, and the magnitude of the pulling force affect the mean translocation time, denoted as \( τ \). We observe a linear decrease in the total free energy change, (n), associated with confinement, which consistently remains negative. The simulation results of our study reveal that \( τ \) exhibits three distinct regimes and the non-monotonic variation with the aspect ratio \(δ\), for fixed total chain size \(N\) and grafting density ρ. Similarly, the width of the nanochannel and nanopore size significantly influence the dynamics of translocation, such that τ exhibits two distinct regimes: the narrow and wide regimes for both the nanochannel and nanopore. For fixed N and side chain length Nsc, while varying ρ, we find that, τ decreases monotonically with the grafting density. We also find a power-law between τ and the backbone length Nbb as, τ ~ Nbbγ, where the scaling exponent γ = 0.86± 0.04 and γ = 0.86± 0.05, for $F = 40$ and $F = 50$, respectively. Additionally, we establish the scaling relations of τ with N and Nbb for fixed side chain number and length, under varying Nbb. Thus, as the side chain length increases from Nsc = 2 to Nsc = 5, we find the power-law dependence of τ with N as τ ~ Nα, where α shows a crossover from α = 2.58 ± 0.02 to α = 3.26 ± 0.15. Similarly for varying ρ and N, we obtain a power-law dependence of τ on Nbb as τ ~ Nbbγ, where γ shows a crossover from γ = 1.57 ± 0.09 to γ = 1.33 ± 0.06. Moreover, the inverse proportionality of τ with the pulling force as τ ~ F⁻¹ is another finding of this study. These results advance the fundamental understanding of polymer architecture on translocation dynamics, providing key insights for nanopore-based polymer transport applications.