Sunday, 24 September, 2006
Shear-Flow-Induced Unfolding of Polymeric Globules
A. Alexander-Katz, M. F. Schneider, S.W. Schneider, A. Wixforth and R. R. Netz -
Phys. Rev. Lett. 97, 138101 (2006)
The behavior of a single collapsed polymer under shear flow is examined using hydrodynamic simulations and scaling arguments. Below a threshold shear rate y , the chain remains collapsed and only deforms slightly, while above y the globule exhibits unfolding/refolding cycles. Hydrodynamics< are crucial: In the free draining case, y scales with the globule radius R as y~R-1, while in the presence of hydrodynamic interactions y ~R. Experiments on the globular von Willebrand protein confirm the presence of an unfolding transition at a well-defined critical shear rate.