Channel confinement of flexible and semiflexible macromolecules.

We compare in detail the channel confinement of flexible and semiflexible chains over a broad range of confinements and chain lengths using molecular simulations. Flexible and semiflexible chains differ over the regimes involved under confinement. For the stiff chain we confirm a transition between strong and weak confinement at the tube diameter approximately equal to the chain persistence length. Deviations from the predicted behavior for confined semiflexible macromolecules in the tubelike channel under the weak confinement are explained by a tendency of chains toward ideal chain behavior. There are several indicators of this ideality based on the shape of chain extension R-confinement D curves, on the scaling of R with the chain length, on the structure factor of coil in the range of individual blobs in the channel, on ambiguity in introduction of excluded volume for confined stiff chains in theoretical treatments as well as on the reported experimental observation.