Observing phase separation of temperature-responsive colloids under shear
Date:
Excerpt of abstract: We use colloidal microgel particles, PNIPAM and PNIPMAM, in a colloid-polymer system to study phase separation. We synthesize particles of various sizes and characterize their temperature-tunable size with differential dynamic microscopy. When these colloidal particles are mixed with a depletant we observe fluid-fluid phase separation as well as gelation. The process of phase separation is observed using a custom-built light-sheet microscope. With a two-color fluorescent labeling scheme we can track single colloidal particles as well as the phases that emerge as an originally-mixed sample phase separates. Furthermore, we observe our samples under shear in both a custom-built cylindrical shear cell with our light-sheet microscope and in a commercial rheometer using brightfield microscopy. Studying the behavior of multiphase systems like our colloid-polymer samples strengthens our understanding of non-equilibrium thermodynamics while providing novel routes for structuring complex fluids.