Molecular Simulation of Biaxial Nematic Liquid Crystals

Colloids consist of supramolecular nanoparticles dispersed in a solvent. While the
prefix nano indicates that these particles have at least one of their dimensions in the submicrometer range, the term supramolecular stresses that their characteristic length scale, typically between 10 nm and 10 μm, is significantly larger than that of conventional molecules. The dynamics of colloidal particles is substantially controlled by the collisions with the solvent molecules and is usually referred to as Brownian motion, originating from a thermal energy of the order of kT per particle.

Colloids of anisotropic particles exhibit a specially rich phase behaviour including many LCs, which are states of matter with properties in between those of a crystal and a fluid. LCs are usually classified in terms of positional and orientational order. In particular, nematic LCs exhibit long-range orientational order, but lack long-range positional order. The uniaxial nematic (NU) phase has a single director indicating the preferred direction of the orientationally ordered particles, while the N B phase exhibits 3 orthogonal directors. This unique feature has made the NB phase an appealing candidate for display devices.
Nevertheless, stable NB phases are rarely observed because competing LC morphologies (e.g. smectic phase) limit or preclude its existence.

The experimental discovery of a highly stable colloidal NB phase at room temperature has opened up an opportunity to consider its applicability in displays. However, prior to exploring the feasibility of this challenging technology, it is crucial to acquire a full picture of the laws underpinning the equilibrium and dynamical properties of colloidal NB phases, whose fundamental understanding constitutes the aim of this project.