Pressure of Linear and Ring Polymers Confined in a Cavity

Nanoscaleconfinement of polymers in a cavity is central to a varietyof biological and nanotechnology processes. Using the discrete WLCmodel we simulate the compression of flexible and semiflexible polymersof linear and ring topology in a closed cavity. Simulation revealsthat polymer pressure inside the cavity increases with the chain stiffnessbut is practically unaffected by the chain topology. For flexiblepolymers, the computed dependence of pressure on the cavity size andpolymer concentration is consistent with the scaling behavior expectedfor bulk polymers in a good solvent. However, the scaling behaviorof semiflexible polymers is only in partial agreement with the theoryprediction, with discrepancies arising from a continuous transitionbetween regimes in chains of moderate lengths. The computed segmentdensity profiles endorse the propensity of semiflexible polymers toconcentrate beneath the cavity surface and thus elevate the pressure.The compaction of polymers by compression into the disordered globuleor growing toroidal structure is documented.

Automated summary

Simulation study reveals that the pressure of polymers increases with chain stiffness but is not affected by chain topology in a closed cavity. For flexible polymers, the computed pressure dependence on cavity size and polymer concentration is consistent with the expected scaling behavior. However, the scaling behavior of semiflexible polymers only partially agrees with the theory prediction due to the continuous transition between regimes for chains of moderate lengths. The computed segment density profiles support the tendency of semiflexible polymers to concentrate beneath the cavity surface and elevate the pressure. The compaction of polymers into disordered globules or growing toroidal structures is demonstrated.