INFLUENCE OF POLYDISPERSITY ON THE PHASE-BEHAVIOR OF COLLOIDAL LIQUID-CRYSTALS - A MONTE-CARLO SIMULATION STUDY

Using isobaric semigrand Monte Carlo simulations, we have investigated the phase behavior of a model for polydisperse rodlike colloids. The system consists of hard spherocylinders in the limit of infinite aspec t ratio, with polydispersity in the length of the particles. If the po lydispersity is small (standard deviation s<0.08), the phase behavior is essentially unchanged from that observed in monodisperse systems; t hus nematic, smectic, and crystal phases are exhibited. For an interme diate range of polydispersities (0.08<s<0.18), the smectic phase is fo und to become increasingly destabilized with respect to the nematic ph ase at low densities and a columnar phase at high densities. This even tually leads to a terminal polydispersity (s approximate to 0.18) abov e which the smectic phase is no longer stable. Beyond this value, only nematic and columnar phases are observed. (C) 1998 American Institute of Physics.