Shear Modulus and Specific Heat of the Liquid-Crystal Blue Phases

We report high-precision measurements of the shear modulus, viscosity, and specific heat of cholesteryl nonanoate through its blue phases (BPI-BPIII). For BPI and BPII we find a shear modulus which remains finite as the frequency approaches zero, indicating that they are viscoelastic solids. We find that the cholesteric and BPIII have a viscoelastic behavior similar to each other and that as expected the isotropic phase is a Newtonian fluid. Both our mechanical and calorimetric data show for the first time that BPIII is a stable and distinct thermodynamic phase.