Stress, strain, and molecular pain: flow driven polymer scission

Polymer additives are commonly used as rheological modifiers due to their ability to dramatically alter fluid properties at low concentrations. The flow of polymer solutions through porous media has been found to produce turbulent-like flow fluctuations, even in inertialess regimes, providing enhanced transport and production in applications ranging from packed bed reactors to enhanced oil recovery. This puzzling behavior results from polymer chains stretching as they pass through confined pore spaces. Yet, the chaotic flows that generate these beneficial effects also pose a considerable threat to these finitely extensible chains through molecular scission. The resulting lower molecular weight fragments reduce the effectiveness of the polymer solution. Here, we use a multi-scale approach to characterize polymer scission from flow through porous media under field-relevant conditions by combining macroscopic pressure drop measurements, pore-scale flow visualization, and molecular-scale structural characterization. By integrating polymer physics with complex fluid dynamics, we aim to clarify the physical mechanisms driving polymer scission in complex three-dimensional porous media.