Order–Disorder Transitions in Model Liquids of Mesogenic Trimers

Monte Carlo simulations have been performed for realistically dense liquids of model trimers consisting of rigid cores connected by virtual bonds representing semiflexible spacers. The conformational characteristics of the trimers are approximately regulated in two cases to mimic (CH₂)_n spacers with n odd or even. All simulated systems undergo reversible isotropic–nematic phase transitions at well defined temperatures, showing odd–even oscillations in good agreement with experiments. The transitions are coupled with a conformational selection favoring extended conformations in the nematic liquids. The odd–even oscillations and the conformational distribution in the nematic liquids are fully explained on the basis of the intrinsic conformational characteristics of the model trimers.