(298c) Dynamic Crystalline Structures of Flowing 2-D Foams in Microfluidic Devices

The groundbreaking work of Bragg and Nye in the 1940s on soap bubble rafts as 2-D analogs of metal crystals, and the ability to form a 3-D crystalline structure from multiple bubble layers has received renewed interest over the last decade. Foam crystals have already found applications in tunable 2-D diffraction gratings and the 3-D formation of highly structured porous solids. Utilization of a flow-focusing microfluidic device enables the rapid generation of stable, ordered monodisperse foams with simple tuning parameters: the fluid flow rates, the fluid properties, and the geometrical dimensions of the device. Here, I will present work focusing on the dynamic crystalline structure of these flowing foams in the wet limit in a wide (2000 µm) collection channel. The influence of the flow parameters on plastic deformation, recrystallization (i.e. the stability of defects, such as dislocations and grain boundaries), and the direct formation of long range crystalline order can be readily visualized and analyzed.