Simons Supports Penn Physicists Who Discover Why Drying Liquid Crystal Drops Leave Unusual ‘Coffee Rings’
In previous papers, University of Pennsylvania physicists investigated the “coffee ring effect,” the ring-shaped stain of particles left after drops of coffee evaporate. In one paper, they learned how to undo this effect by altering particle shape. Now, in a new paper published in Nature Communications, they have uncovered the complex and remarkably different behavior arising in a liquid crystal drop that is drying.
The research, carried out in collaboration with scientists at Lehigh University and Swarthmore College, reveals novel behavior characteristics of liquid crystals, fluids with aligned phases of constituent molecules. The formation of different phases during drying leads to dramatically different fluid movement and solid deposition and also provides insight needed for the control of drying solutions of macromolecules that occur in many dyes and pharmaceutical formulations.
Penn alumnus Zoey Davidson, now a postdoc at the Max Planck Institute for Intelligent Systems in Germany, had been experimenting with Sunset Yellow, a dye that gives Doritos and orange soft drinks their bright colors, when he accidentally spilled some of the material. . .