In the broadest sense, the focus of this thesis concerns the role of entropy in macroscopic systems related to liquid crystals in equilibrium. We be- gin by defining a broad generalisation of the Ball-Majumdar potential, applicable to a wide variety of order parameter models relevant to liquid crystals. First we provide a geometric characterisation of the set of ad- missible order parameters for general systems. We demonstrate the key properties of convexity, regularity, and blow up ...