Ejection Time of a Semi-Flexible Polymer from Strong Confinement inside a Nano-slit

Abstract

Advances in nano-fabrication techniques have enabled confinement of polymers at nano-scale cavities. This has raised a higher demand for development of theories for polymers in severe confinements. In this manuscript, the escape of a polymer confined in a nano-slit through a nano-pore in the strong confinement regime is investigated, theoretically and by using Langevin Dynamics (LD) simulations. The strong confinement occurs when the height of the nano-slit becomes smaller than the persistence length of the polymer. Persistence length is a measure of the polymer stiffness. The radius of gyrations R_g, the confinement force on the polymer f, and the ejection time of the polymer τ are obtained in different values of the polymer length L, the height of the nano-slit D, and the persistence length of the polymer P. The simulation results are well described with the scaling relations R_g/L^0.75 ~(P/D)^0.25 and f/L~(PD^5 )^(-0.4) and τ/L^2 ~(PD^2 )^0.42, respectively. The simulation results are in rather good agreement with the theory. It seems that the relative difference between theory and simulations is due to being close to the transition region between weak and strong confinement regimes.