LAUSR

We aim to clarify how the chain length influences the critical flow rate (qc) for flexible linear chains translocating through cylindrical nanopores in the whole length range (9.5 > R/r > 1.0), where R and r represent the chain size and the pore size, respectively. By studying the translocation behavior of both mono- and polydisperse polystyrenes through 20 nm nanopores, we have, for the first time, experimentally revealed that there exist two different translocation regimes, i.e., strong and moderate confinement regimes. In the strong confinement regime (R/r > λ*), qc is found to be independent of the chain length, consistent with the prediction by classical theories, while in the moderate confinement regime (R/r < λ*), qc increases with the chain length significantly, where λ* represents the critical relative chain length. Theoretically, λ* is determined by the critical penetration length (l*), at which the free energy change (ΔE) of a translocating chain reaches its maximum value (ΔE ∼ kBT). For longer...