Chiral helical nanofilament and nanocylinder phases and a new type of polymorphism in liquid crystals*

Helical nanofilaments, consisting of bundles of twisted smectic layers with a helical pitch of 200 nm, are formed by achiral bent-core liquid crystal (BC-LC) molecules due to an intralayer mismatch between top and bottom molecular halves relieved by local saddle-splay. Here, by introducing a chiral center to one of the sides of asymmetric BC-LCs (shorter side, called meta-side), we observed the first example of the polymorphism in liquid crystalline materials. They form a not heretofore helical microfilament (HF) phase upon rapid cooling and an oblique columnar upon slow cooling.¹Interestingly, another not reported morphology observed when the chiral center migrates to the longer para-side). In this case, the BC-LC molecules form layers that are rolled up into coaxial cylinders resulting in the formation of heliconical-layered nanocylinders (HLNCs).²HLNCs form within 80-100 nm width and micrometer lengths. This optically active cylinders form feather-like structures, braid, and assemble into hollow structures totaling six levels of hierarchical self-assembly.
[1] Li, Lin, et al. Nature communications 9.1 (2018): 714.
[2] S. Shadpour, et al. (HLNCs) – hierarchical self-assembly in a unique B4 phase liquid crystal polymorph, submitted (2018).