(322d) Nonequilibrium Free Energy Landscapes of Flowing Polymer Solutions

In this work, we report the direct determination of the free energy of dilute polymer solutions in flow. In general, thermodynamic properties define a system at steady state. For equilibrium steady states, the free energy landscape allows for the determination of a wide array of system properties. However, flowing polymer solutions are generally considered as nonequilibrium steady states wherein the nonequilibrium free energy landscape is a relevant quantity. Recently, we developed a framework based on the Hatano-Sasa equality that allows for the determination of energy landscapes of polymer molecules in flow by analysis of purely dynamic properties. Using this framework in conjunction with Brownian dynamics simulations, we determined the nonequilibrium Helmholtz free energy landscape of dsDNA molecules driven by a planar extensional flow.  Furthermore, we show that nonequilibrium energies can be used to determine equilibrium properties such as polymer relaxation time and chain elasticity. Taken together, our work provides a framework that enables the determination of fundamental nonequilibrium thermodynamic properties from measurable quantities in soft matter dynamics.