Nano-confinement of chiral liquid crystals gives rise to exotic blue phases*

Blue phases (BPs) arise spontaneously in chiral liquid crystals (ChLCs) as a means to minimize the global free energy, by forming networks of defects with specific cubic symmetries. By confining BPs we introduce an approach to manipulate their structure through geometrical frustration. In this work, we present a new family of BPs by modeling ChLCs in toroidal and cylindrical cavities. The configurations are obtained following a theoretically-informed Monte Carlo relaxation of the free energy functional, which is described in the framework of the Landau-de Gennes formalism. We vary temperature and chirality to build phase diagrams and summarize the portfolio of chiral morphologies, which can be classified into twisted cholesterics, and BPs with helical and cubic symmetries. We also study the effects of surface anchoring and curvature to highlight the stability of these new phases. The formation of these new kind of morphologies offers interesting opportunities to direct the assembly of macromolecules and colloids at the nanoscale.