Entropy-driven formation of prolate and oblate cholesteric phases by computer simulations

Abstract

Predicting the macroscopic chiral behaviour of cholesteric liquid crystals from the microscopic chirality of the particles is highly non-trivial, even when the chiral interactions are purely entropic in nature. Here we introduce a novel chiral hard-particle model, namely particles with a twisted polyhedral shape and obtain, for the first time, a stable fully-entropy-driven cholesteric phase by computer simulations. By slightly modifying the triangular base of the particle, we are able to switch from a left-handed prolate to a right-handed oblate cholesteric using the same right-handed twisted particle model. Furthermore, we find qualitative agreement with an Onsager-like theory, suggesting that the latter can be used as a quick tool to scan the huge parameter space associated to the microscopic chirality. Our results unveil how the competition between particle biaxiality and chirality is reflected into the nematic self-organization and new theoretical challenges on the self-assembly of chiral particles can be undertaken.