Abstract
Blue phases are characterized by three-dimensional periodic structures self-assembling in chiral nematic—cholesteric liquid crystals (CLCs). They paradoxically combine the fluidity of liquids with the elasticity of crystalline solids. We develop a theoretical approach based on an integral order parameter within the framework of Landau–de Gennes phenomenological theory and analyze the stability, temperature-induced phase transitions and elasticity of cubic blue phases of CLCs. In addition to the already known phases, we predict a new one, the beta-phase, with significantly different structure although characterized by the same spatial symmetry as BP I. We calculate the elastic moduli of the BP I and BP II phases using the free-helix approximation for the case of strongly chiral CLCs and the interpolation model for moderately chiral CLCs. We discuss the possibility of negative Poisson’s ratio of cubic blue phases depending on the relative values of orientational elastic moduli of the chiral nematic.