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-III). Our mechanical measurements as a function of temperature and frequency show clear evidence for the phase sequence Cholesteric ->BPI->BPII->BPIII->Isotropic which agrees with optical measurements and precision specific heat data. For BPI and BPII we find a shear modulus which remains finite as the frequency approaches zero, indicating that they are viscoelestic solids.