The stretching force on a tethered polymer in pressure-driven flow.

We use mesoscopic lattice-Boltzmann/molecular dynamics simulations to study the stretching behavior of a single tethered polymer in micro- and nanochannels. In particular, we are interested in the connection between fluid flow properties and the force on the polymer chain. An analytical expression for the stretching force is proposed, which linearly depends on the number of monomers and the boundary shear rate. In agreement with theory, the numerical findings reveal that the influence of hydrodynamic interactions can be ignored, which is also supported by results of additional Langevin dynamics simulations. Our simulation data coincide with the analytical expression for the fractional extension of the chain and further indicate that even weak Poiseuille flow profiles induce a strong alignment of the chain along the channel walls. The numerical results are in good agreement with experimental data obtained by microfluidic stretching of tethered λ-DNA.