Topological Defects with Tunabel Chirality and Morphology Induced by 3D-Printed Square Networks

Topological defects exist widely in the orientationally ordered matter such as nematic liquid crystal. Their morphphology and topological properties can be controled by topology and anchoring conditions of their boundaries, Here we used two photon printing technique to make microscale square networks and study topological defects they induce in nematic liquid crystals. We found that when the substrate distance increases from 2.5 μm to 20 μm, the induced topological defects change from a -1/2 disclination loop to a hyperbolic defect located at the center, and ultimately transform into off-entered point defects. In the hyperbolic defect case, a chiral twist is emergent in central area. We found that the twist of the chiral areas can be fine tuned by an external electric field. By using the Landau-De Gennes theory, we explored how the boundary conditions influence on topological defects morphology and free energy. The simulation results yielded good agreement with the experiment observations. Further, we found that the chirality of the central adrea can be predesigned by introducing slight chirality in the squares networks.