Longitudinal response of confined semiflexible polymers

The longitudinal response of single semiflexible polymers to sudden
changes in externally applied forces is known to be controlled by
the propagation and relaxation of backbone tension. Under many
experimental circumstances, realized, for example, in nanofluidic
devices or in polymeric networks or solutions, these polymers are
effectively confined in a channel-or tubelike geometry. By means of
heuristic scaling laws and rigorous analytical theory, we analyze
the tension dynamics of confined semiflexible polymers for various
generic experimental setups. It turns out that in contrast to the
well-known linear response, the influence of confinement on the
nonlinear dynamics can largely be described as that of an effective
prestress. We also study the free relaxation of an initially
confined chain, finding a surprising superlinear similar to t(9/8)
growth law for the change in end-to-end distance at short times.