Entropy-driven formation of chiral nematic phases by computer simulations

• Published in: Nature communications 2016-04, Vol.7 (1), p.11175-11175, Article 11175
• Main Authors: Dussi, Simone, Dijkstra, Marjolein
• Format: Article
• Language: English
• Subjects: 639/301/1034; 639/301/119/2795; 639/301/923/919; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms11175

Predicting the macroscopic chiral behaviour of 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 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 (calamitic) to a right-handed oblate (discotic) cholesteric phase using the same right-handed twisted particle model. Furthermore, we show that not only prolate and oblate chiral nematic phases, but also other novel entropy-driven phases, namely chiral blue phases, chiral nematic phases featuring both twist and splay deformations, chiral biaxial nematic phases with one of the axes twisted, can be obtained by varying particle biaxiality and chirality. Our results allow to identify general guidelines for the stabilization of these phases. The entropy-driven formation of cholesteric liquid crystal, one of the widely used liquid crystal phase, has not yet been addressed in simulations due to large unit cells. Here, Dussi and Dijkstra overcome this problem by introducing a hard-particle model and show that shape alone can stabilize a chiral nematic phase.