When a liquid crystal forming particles are confined to a spatial volume with dimensions comparable to that of their own size, they face a complex trade-off between their global tendency to align and the local constraints imposed by the boundary conditions. This interplay may lead to a non-trivial orientational patterns that strongly depend on the geometry of the confining volume. This novel regime of liquid crystalline behavior can be probed with colloidal particles that are macro-aggregates of biomolecules. Here we study director fields of filamentous fd-viruses in quasi-2D lens-shaped chambers that mimic the shape of tactoids, the nematic droplets that form during isotropic-nematic phase separation. By varying the size and aspect ratio of the chambers we force these particles into confinements that vary from circular to extremely spindle-like shapes and observe the director field using fluorescence microscopy. In the resulting phase diagram, next to configurations predicted earlier for 3D tactoids, we find a number of novel configurations. Using Monte Carlo Simulations, we show that these novel states are metastable, yet long-lived. Their multiplicity can be explained by the co-existence of multiple dynamic relaxation pathways leading to the final stable states.

The Netherlands Organisation for Scientific Research (NWO)
Sci. Rep.
Theory of Biomolecular Matter

Gârlea, I., Dammone, O., Alvarado, J., Notenboom, V., Jia, Y., Koenderink, G., … Mulder, B. (2019). Colloidal Liquid Crystals Confined to Synthetic Tactoids. Sci. Rep., 9(1), 20391: 1–11. doi:10.1038/s41598-019-56729-9