(179f) Dynamics of Macromolecules in Two-Dimensional Linear Flows with Rotation: Is There Another Coil-Stretch Transition?

In his seminal paper more than 30 years ago, de Gennes predicted that a polymer molecule in an external flow may undergo a coil-stretch transition due to a competition between the hydrodynamic stretching force and the entropic spring force driving relaxation towards the equilibrium coiled state. In this talk we argue that in linear flows with nonzero vorticity a macromolecule is stabilized not only by the entropic forces, but also by the rotational flow component which misaligns the particle with the extensional axis of the flow. We predict that under some conditions two fluctuating stationary states of a macromolecule may thus exist, associated with the two stabilizing mechanisms. One state is nearly isotropic and it is stabilized primarily by rotation, and the other is elongated and stabilized primarily by the entropic springs. For sufficiently strong flows the elongated state may undergo a second transition to a fully stretched state.