Static and Dynamic Structural Characterization of Yield Stress Fluids for Direct Ink Writing

Direct ink writing (DIW) is a three-dimensional (3D) printing technique that involves the continuous extrusion of yield stress fluids (YSF). These YSFs must be able to flow through narrow nozzles, re-structure in short timescales upon deposition and retain the predesigned 3D shape. Understanding the links between the structure and assembly of constituent (macro)molecules in YSF and their rheology is central to successful manufacturing via DIW. However, local structures and microscopic dynamics within YSF can be highly heterogeneous, which impact printing performance and the structural features of final printed parts. We have new experimental results from rheo-microscopy experiments, combining particle tracking and cross-polarised imaging, which reveal some novel structural transitions and local flows in two model YSF systems.We request static SANS and rheo-SANS measurements, coupled with polarised imaging, to understand the nanoscale assemblies responsible for these observations to advance our understanding of these YSFs, and to unlock a step change in formulation for DIW.