Translocation of polymers out of confined geometries

We consider the free energy of confinement for a flexible self-avoiding polymer inside a spherical cavity. Accurate numerical calculations allow us to arbitrate between competing scaling predictions. We find that, for moderate confinement, the free energy exhibits a power-law dependence on cavity size that is different from what is observed for planar and cylindrical confinement. At high monomer concentrations, crossover to another scaling regime occurs. One of the consequences of these findings is a new prediction for the escape time of a polymer from a spherical confinement. By means of additional simulations, we confirm that the translocation time can be described by a scaling law that exhibits a nonlinear dependence on the degree of polymerization that is sensitive to the nature of the confining geometry. The geometry dependence contradicts earlier predictions but is in quantitative agreement with findings for the free energy of confinement. © 2007 Elsevier B.V. All rights reserved.