Thick liquid crystalline cholesteric shells

Abstract

We numerically investigate the phase behavior of thick shells of cholesteric liquid crystals with tangential anchoring at the shell boundary. For achiral liquid crystals, we demonstrate a thickness-dependent transition from a configuration featuring four disclination lines connecting the inner and outer surfaces to a defect-free bulk state, where each surface is topologically isolated and features two boojums. Incorporating chirality stabilizes defect arrangements, including a mixed state combining boojums and disclination lines, as well as blue phases at high chirality, and we show that shell thickness strongly modulates these transitions. We exploit the metastable features of the observed phases to obtain an elastically induced rearrangement of the shell surfaces during a cholesteric hysteresis cycle, stabilizing an alternative configuration that minimizes the free energy at low chirality. Finally, we consider the case of shells featuring multiple inner isotropic cores, that induce a topological and morphological reorganization, where some inclusions form a connected cluster with the outer shell, while the remaining inclusions become isolated. Our work paves the way for exploring dynamic behaviors under external fields, mixed anchoring conditions, or active flows.