Phase Behavior Of Colloidal Elongated Dumbbells & Lollipops

Abstract

We perform Monte Carlo simulations on hard elongated dumbbells and lollipops. The dumbbells are modeled as hard spherocylinders with a hard sphere attached at each end. For the lollipops one of these spheres is removed. Like in a system of hard spherocylinders we find that both shapes self-assemble into nematic and smectic liquid crystal phases. Our results show that the hard spheres destabilize the nematic phase with respect to the isotropic phase, whereas an increase in length of the particles increases the stability. Moreover, the spheres destabilize the smectic, AAA- and ABC-crystal ordering but give rise to the formation of a columnar phase. The existence of a cholesteric phase is studied by forcing the system in a cholesteric phase via a chiral potential. Simulation results are inconclusive, longer simulations are needed to equilibrate the systems further. A possible smectic-c phase is observed for the hard lollipops.