A flexible polymer confined inside a cone-shaped nano-channel.

The nano-scale confinement of polymers in cone-shaped geometries occurs in many experimental situations. A flexible polymer confined in a cone-shaped nano-channel is studied theoretically and by using molecular dynamics simulations. Distribution of the monomers inside the channel, configuration of the confined polymer, the entropic force acting on the polymer, and their dependence on the channel and the polymer parameters are investigated. The theory and the simulation results are in very good agreement. The entropic force on the polymer that results from the asymmetric shape of the channel is measured in the simulations and its magnitude is found to be significant relative to thermal energy. The obtained dependence of the force on the channel parameters may be useful in the design of cone-shaped nano-channels.