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,ΔF(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 ratioδ, for fixed total chain sizeNand grafting densityρ. 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 fixedNand side chain lengthNsc, while varyingρ, we find that,⟨τ⟩decreases monotonically with the grafting density. We also find a power-law between⟨τ⟩and the backbone lengthNbbas,⟨τ⟩∼Nbbγ, where the scaling exponentγ=0.86±0.04andγ=0.86±0.05, forF = 40 andF = 50, respectively. Additionally, we establish the scaling relations of⟨τ⟩withNandNbbfor fixed side chain number and length, under varyingNbb. Thus, as the side chain length increases fromNsc=2toNsc=5, we find the power-law dependence of⟨τ⟩withNas⟨τ⟩∼Nα, whereαshows a crossover fromα=2.58±0.02toα=3.26±0.15. Similarly for varyingρandN, we obtain a power-law dependence of⟨τ⟩onNbbas⟨τ⟩∼Nbbγ, whereγshows a crossover fromγ=1.57±0.09toγ=1.33±0.06. Moreover, the inverse proportionality of⟨τ⟩with the pulling force as⟨τ⟩∼F-1is 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.