(328j) Interpreting Non-Gaussian Deformations from Scattering of Polymers in Extreme Shear Flows

Applications of high molecular weight dilute polymer solutions typically involve extreme shear rates that cause nonlinear deformations at the molecular level. Although various microscopy methods have been successful for resolving single-molecule deformations for specific biopolymer systems (e.g. DNA), these methods are inaccessible to conventional, synthetic polymers. Recent in situ measurement capabilities using a capillary device allow us to extract microstructural information from SANS measurements about flow-induced deformation at extreme shear rates (~10⁶ s^-1) and holds excellent potential for single-molecule studies. However, previously developed analyses for anisotropic scattering of polymers in flow are limited to Gaussian chains, and thus are inadequate for nonlinear strains and strain rates. We introduce a new modeling framework that resolves non-Gaussian deformations of polymers in high shear flows through moments of the chain conformation distribution. The method is then validated using synthetic datasets from parameter-matched Brownian dynamics simulations, and applied to capillary rheo-SANS measurements on a series of architecturally well-defined polymers at high shear flows in order to test the influence of chain topology on non-Gaussian polymer deformations. We anticipate that this new analysis method will inform the rational design of topologically-defined polymers to optimize their performance in their applications as rheological modifiers.