Capillary nematization of hard colloidal platelets confined between two parallel hard walls

We use density functional theory to study the capillary phase behaviour of a discotic system of colloidal platelets that are confined in a planar slit pore. The model plates have circular shape, continuous orientations and vanishing thickness; they interact via hard-core repulsion with each other and with the walls which induces homeotropic wall anchoring of the nematic director. We find that the isotropic-nematic capillary binodal is shifted to lower values of the chemical potential as compared to bulk isotropic-nematic coexistence. Capillary isotropic-nematic coexistence vanishes below a critical wall separation distance which is significantly larger than it is in a reference system of thin hard (Onsager) rods confined between two parallel hard walls that act on the particle centres.