Conformation And Drift Of A Telechelic Chain In Porous Media

The conformation and drift properties of a telechelic chain moving through a porous host of randomly distributed static obstacles are studied using Brownian dynamics simulation for a Grest-Kremer bead-spring model of polymer. Static chain conformations exhibit non-monotonic behaviour as a function of the impurity density ρimp at zero bias. The chain initially shrinks due to an entropic barrier as the density of the obstacles ρimp is increased. In the presence of the obstacles it requires only a tiny bias for a long chain to be mostly stretched. We then study the drift property of the chain as a function of the bias and impurity density. The drift velocity of the chain saturates beyond a threshold bias Fxcrit. This observation can be useful in designing DNA sequencing methods based on electrophoretic mobility