Effect of Solvent Viscosity on the Driven Translocation of Charged Polymers through Nanopores

The effect of viscosity of non-translocated(cis)side,ηcis,on the driven translocation of charged polymers through nanopores is investigated using Langevin dynamics simulation.Results show that the translocation of polymer chains can be regulated by changingηcis.Asηcis decreases,the translocation timeτdecreases,and the exponentδin the scaling relation with driving force f,τ~f-δ,increases whereasαin the scaling relation with chain length N,τ~Nα,decreases.Simultaneously,the conformation of the polymer chain at the cis side gravitates towards an equilibrium state.The results imply a relationship between the translocation and the conformation of polymer chains.To verify this hypothesis,we change the conformation of polymer by artificially relaxing the translocating polymer via adding an additional relaxation time in the simulation.A sufficient large additional relaxation time for the translocating polymer chain at the cis side only or at both cis and trans sides results in exponentsαandδboth close to 1,in contrast toα=1.36 andδ=0.8 for the translocation without the additional relaxation.The additional relaxation for the polymer chain at the cis side accelerates the translocation and plays a more important role than that for polymer chain at the trans side.